Acute heart failure

Article written and reviewed by Dr Luca Moretti

Decompensated heart failure is the acute or gradual worsening of the symptoms and signs of heart failure that requires intensification of treatment and, in more severe presentations, intravenous therapy, respiratory support or hospitalization. It is not a single disease: it encompasses the de novo onset of heart disease and destabilization of chronic heart failure, with phenotypes ranging from hypertensive congestion with preserved cardiac output to shock due to severe ventricular failure. The initial priority is not to classify ejection fraction, but to immediately recognize respiratory failure, hypoperfusion, shock and time-sensitive causes. Acute coronary syndrome, mechanical complications of myocardial infarction, aortic dissection, pulmonary embolism, tamponade, unstable arrhythmias, acute valvular regurgitation and hypertensive crisis require interventions directed at the cause that cannot be replaced by diuretics alone. Four clinical presentations are particularly useful: acute congestive heart failure, acute pulmonary edema, isolated right ventricular failure and cardiogenic shock. They may overlap and change with treatment. Blood pressure, perfusion status and the distribution of congestion define the physiology more than ejection fraction does; a patient with HFpEF may be in shock, and a patient with severe HFrEF may present warm and hypertensive.

Congestion with preserved peripheral perfusion, the “warm-wet” profile, predominates in most hospitalizations; a minority of patients have hypoperfusion, with or without congestion, and account for a large share of mortality. The clinical profile is a bedside estimate: blood pressure, extremity temperature, capillary refill, urine output, mental status and lactate must be integrated and reassessed, because the hemodynamic trajectory may change within hours. Increased filling pressures often precede symptoms by days and reflect sodium accumulation, reduced venous capacitance, renal deterioration and neurohormonal activation. In hypertensive pulmonary edema, by contrast, rapid volume redistribution from the splanchnic compartment toward the thorax may cause severe dyspnea without substantial weight gain. This distinction guides the combination of vasodilators, ventilation and diuresis; hospitalization is both a prognostic event and a therapeutic opportunity. Resolution of dyspnea alone does not guarantee resolution of congestion, and discharge with persistently elevated venous pressure increases the risk of recurrence. During stabilization, the etiology and precipitating factors must be identified, disease-modifying therapies resumed or initiated, and early follow-up arranged.

In-hospital mortality varies considerably with presentation, age, blood pressure, renal function, sodium, troponin and comorbidities; it increases dramatically in shock. Even patients discharged in an apparently stable condition remain vulnerable in the first few months. The modern goal is therefore continuous management from the emergency setting through decongestion, from the transition to oral medications to intensive titration after discharge.

Etiology, pathogenesis and pathophysiology

De novo acute heart failure may result from myocardial infarction, myocarditis, Takotsubo syndrome, sudden valvular regurgitation, hypertensive crisis, arrhythmia, pulmonary embolism or the onset of cardiomyopathy. In patients with chronic disease, exacerbation emerges from the interaction between progression of the substrate and one or more precipitants. Labeling the episode simply as “nonadherence” without investigating ischemia, infection, valvular disease, rhythm and iatrogenic factors exposes the patient to recurrence; acute coronary syndrome reduces function through necrosis, ischemia of the remaining myocardium, stunning, arrhythmias and mechanical complications. Right ventricular infarction produces preload dependence and low cardiac output; papillary muscle rupture causes mitral regurgitation and edema; a septal defect and free-wall rupture cause shock. However, elevated troponin is common even without coronary thrombosis and requires assessment of its dynamic changes; an ischemic context is necessary to diagnose myocardial infarction; hypertensive emergencies rapidly increase afterload and end-diastolic pressure, especially in hypertrophied, stiff ventricles. Arterial vasoconstriction reduces forward output, while venous vasoconstriction mobilizes the splanchnic reservoir. The result is pulmonary edema, often with very high blood pressure and without necessarily increased total volume. This pathophysiology makes controlled load reduction a priority alongside respiratory support.

Rapid atrial fibrillation, flutter, supraventricular or ventricular tachycardia reduce filling time and the atrial contribution and increase oxygen consumption. In a stiff ventricle, even a moderately elevated heart rate may precipitate congestion. The arrhythmia may be the cause or an adrenergic response to heart failure; establishing the direction of causation avoids unnecessary cardioversion or aggressive rate control. Bradycardia, atrioventricular block, sinus node dysfunction and pacemaker malfunction may reduce cardiac output and cause functional regurgitation; loss of atrioventricular synchrony is particularly poorly tolerated in HFpEF and mitral stenosis. Heart rate-lowering drugs, ischemia, hyperkalemia and hypothyroidism are reversible causes to investigate before permanent pacing; infections precipitate heart failure through fever, tachycardia, vasodilation, increased demand, hypoxemia, inflammation and fluid administration. Pneumonia, urinary tract infections and sepsis are frequent in older patients. Edema may mimic an infiltrate, and neither procalcitonin nor leukocytosis is absolutely specific; antibiotic treatment should follow timely microbiological and clinical assessment.

Acute pulmonary embolism abruptly increases right ventricular afterload, causing dilation, free-wall ischemia, tricuspid regurgitation and reduced left ventricular filling. Hypotension and hypoxemia may lead to shock. D-dimer, echocardiography and CT angiography are selected according to probability and stability; an extremely high pulmonary pressure may suggest a pre-existing chronic component. Cardiac tamponade limits filling of all chambers and produces tachycardia, narrow pulse pressure, jugular venous distension and pulsus paradoxus, but presentation depends on the rate of fluid accumulation. Pressures may be lower in hypovolemia and more complex in pulmonary hypertension; pericardiocentesis or surgery corrects the cause; diuretics and vasodilators may worsen preload dependence. Acute mitral regurgitation due to papillary muscle rupture, chordal rupture or endocarditis delivers a large volume into a nondilated, poorly compliant atrium, producing severe edema even with a soft murmur. Acute aortic regurgitation rapidly raises ventricular diastolic pressure and may cause premature mitral valve closure; these valvular emergencies require urgent echocardiography, stabilization and surgical or transcatheter assessment.

Fulminant myocarditis and Takotsubo syndrome may cause shock, arrhythmias and edema. In Takotsubo syndrome, low cardiac output must be distinguished from dynamic outflow tract obstruction and mitral regurgitation, because catecholaminergic inotropes may worsen the obstruction. In myocarditis, conduction disturbances, eosinophilia, oncological immunotherapy or refractory arrhythmias may indicate a form requiring early biopsy. Aortic dissection may cause aortic regurgitation, tamponade, coronary ischemia and shock. Sudden pain, pulse or neurological deficits and mediastinal abnormalities are not always present. Anticoagulant or antiplatelet therapy administered for a presumed coronary syndrome may be dangerous, making it essential to retain dissection in the differential diagnosis before irreversible treatments. Progression of aortic stenosis, mitral or tricuspid regurgitation, prosthetic valve thrombosis and endocarditis may destabilize chronic heart failure; the hemodynamic change may be gradual but suddenly exceed reserve during infection or arrhythmia. Prosthetic valve assessment requires comparison with baseline gradients and a search for new obstruction or regurgitation.

NSAIDs, corticosteroids, thiazolidinediones, some chemotherapeutic agents, calcium channel blockers and drugs with a high sodium content may promote retention or cardiotoxicity. Discontinuation of diuretics, RAAS inhibitors or beta-blockers, excess salt, alcohol or stimulants are common precipitants; reconciliation must include over-the-counter medications, herbal remedies and actual adherence, not only prescriptions. Acute renal dysfunction may be both a cause and a consequence of congestion. A reduction in glomerular filtration promotes sodium accumulation; increased renal venous pressure reduces the transrenal gradient; RAAS activation increases proximal and distal reabsorption. So-called worsening renal function during treatment is not uniform: effective decongestion with a modest rise in creatinine differs from tubular injury with hypoperfusion. Severe anemia increases the required cardiac output and may precipitate ischemia; rapid or excessive transfusion may worsen volume overload. Thyrotoxicosis, arteriovenous fistulas, beriberi and sepsis produce a hyperdynamic circulation. In these phenotypes, absolute cardiac output may be high but insufficient for the demand, and treatment must correct the high-output cause.

Congestion results from the balance between venous capacitance, sodium content and pumping function. The splanchnic compartment contains a large stressed and unstressed volume; sympathetic activation reduces its capacitance and shifts blood toward the thorax. Increased left atrial pressure is transmitted to pulmonary veins and capillaries; when filtration exceeds lymphatic drainage and barrier capacity, interstitial and alveolar edema develops. According to Starling forces, hydrostatic pressure, oncotic pressure, permeability and surface area regulate fluid movement. Hydrostatic pressure predominates in cardiogenic heart failure, but inflammation, sepsis and endothelial injury may increase permeability and create a mixed picture. Hypoalbuminemia reduces oncotic pressure and promotes peripheral edema, but rarely explains severe pulmonary edema on its own; the congested lung becomes stiff, increases the work of breathing and alters the ventilation-perfusion ratio. Bronchial mucosal edema increases resistance, while hypoxemia and acidosis stimulate the sympathetic nervous system, worsening vasoconstriction and afterload. Positive pressure does more than provide oxygenation: it reduces venous return and left ventricular afterload and may interrupt the cycle of pulmonary edema, but may harm a preload-dependent right ventricle.

In low-output states, mean arterial pressure and organ blood flow depend on cardiac output and vascular resistance. Compensatory vasoconstriction maintains blood pressure but increases ventricular work and reduces cutaneous, renal and splanchnic perfusion. When compensation fails, lactate, acidosis and inflammation cause vasoplegia and multiorgan dysfunction; initial normotensive shock is possible and requires attention to peripheral signs. An acutely dilated right ventricle develops increased wall tension and oxygen demand, while reduced systemic pressure compromises right coronary perfusion; septal displacement reduces left ventricular filling, and the pericardium limits total expansion. Excessive fluids increase congestion and interdependence; a small fluid challenge is appropriate only when true hypovolemia is present. Acute neurohormonal activation increases renin, angiotensin, aldosterone, vasopressin and catecholamines. Vasoconstriction and sodium reabsorption maintain perfusion but impede decongestion. The distal nephron adapts to chronic diuretic exposure by increasing reabsorption, generating diuretic resistance and post-diuretic natriuresis when the drug concentration falls.

The response to a diuretic depends on its reaching the tubular lumen through proximal secretion, the threshold dose and the time above threshold. Intestinal edema reduces oral absorption; severe hypoalbuminemia alters transport; renal insufficiency requires higher doses; a poor initial response should prompt rapid dose doubling or a rational combination, rather than repeating a subtherapeutic dose for days. Inflammation, oxidative stress and endothelial dysfunction increase during the episode and may persist after compensation. Elevated troponin without myocardial infarction reflects myocardial injury from stress, tachycardia, pressure and microischemia and has prognostic significance; hospitalization is therefore not simply an excess of fluid, but a phase of accelerated biological injury requiring prompt disease-modifying treatment. Hepatic congestion increases bilirubin and alkaline phosphatase; hypoperfusion produces centrilobular necrosis with very high aminotransferases. Intestinal edema reduces absorption and promotes microbial translocation; renal pressure reduces filtration. Progressive organ involvement creates cycles in which the kidneys, liver and intestine perpetuate retention and inflammation.

The warm/cold and wet/dry classification helps guide treatment: warm-wet mainly requires decongestion, cold-wet may require perfusion support in addition to volume removal, and cold-dry requires distinguishing hypovolemia from low reserve. However, these quadrants neither replace identification of the cause nor quantify pressures and cardiac output; they must be reassessed serially; systolic blood pressure at admission is a powerful phenotypic indicator. High values suggest reserve and vasoconstriction, allowing vasodilation; low values suggest reduced cardiac output or mechanical disease and limit many drugs. The trend after treatment is more informative than a single number and must be interpreted together with diastolic pressure, pulse pressure and organ perfusion. Not all episodes are preventable, but many are preceded by increased pulmonary pressure, reduced activity, altered heart rate and worsening adherence; intervention before overt symptoms may prevent hospitalization in monitored patients. Prevention nevertheless requires a clinical response to warning signals and effective treatment of the substrate, not simply the collection of remote data.

An excessive fluid or sodium load in the emergency department, perioperatively or during oncological therapy may precipitate the syndrome, especially in HFpEF and renal insufficiency. Assessment of “effective circulating volume” must not translate into repeated boluses for every episode of hypotension; the response to a small challenge, ultrasound and selected dynamic indices help avoid iatrogenic overload. Abrupt withdrawal of a beta-blocker increases adrenergic activity and may promote tachycardia and ischemia; discontinuation of RAAS inhibitors and diuretics facilitates retention. Conversely, continuing high doses during shock or severe kidney injury may be harmful; management requires a documented reason for each discontinuation and a date or condition for resumption. High sodium intake rarely acts alone, but may exceed the ability of an already activated kidney to excrete the load. Beverages, preserved foods, effervescent preparations and infusions are hidden sources. Education must not blame the patient, because costs, food culture and access to fresh food influence actual exposure.

Extreme temperatures increase risk: heat causes vasodilation, dehydration and changes in diuretic use; cold increases blood pressure and vasoconstriction. Pollution and seasonal respiratory infections add stress; self-care plans must include agreed adjustments, avoiding patients independently changing essential medications on the basis of the weather. Pregnancy and the puerperium may precipitate peripartum cardiomyopathy, stenotic valvular disease, pulmonary hypertension or congenital heart disease. Preeclampsia causes edema through afterload, endothelial dysfunction and permeability, not always through systolic dysfunction. Medications and imaging must consider the fetus and breastfeeding without delaying treatment of a maternal emergency. Postoperatively, bleeding, vasoplegia, ischemia, tamponade, arrhythmias, ventilation and the inflammatory response may produce low cardiac output. After cardiac surgery, low cardiac output syndrome has specific physiology and forms of support; after noncardiac surgery, myocardial injury and fluids must be considered. The perioperative hemodynamic trend is often more informative than a single biomarker.

Device dysfunction may rapidly precipitate heart failure: loss of resynchronization, pacemaker-mediated tachycardia, repeated shocks, thrombosis or malfunction of a ventricular assist device. Device interrogation and assessment of the pacing percentage are part of diagnosis; an apparently “paced” ECG does not prove effective capture. In patients with Fontan circulation or a systemic right ventricle, pressures and dependence on venous return differ from biventricular physiology. Atrial arrhythmias and increased pulmonary vascular resistance may cause collapse; management of fluids, ventilation and rhythm requires a center for congenital heart disease. COPD exacerbation increases right ventricular afterload through hypoxia, hypercapnia and intrathoracic pressures; beta-agonists cause tachycardia and increased lactate. COPD and edema may coexist, and a response to bronchodilators does not rule out congestion. Cardioselective beta-blockers should not automatically be discontinued after stabilization solely because of the name of the comorbidity.

An acute decrease in hemoglobin due to bleeding reduces oxygen transport and may precipitate ischemia and high cardiac output. Transfusion is decided according to hemoglobin, symptoms, ischemia and bleeding and is administered cautiously in volume overload; TACO, transfusion-associated circulatory overload, must be distinguished from permeability-related TRALI. Deterioration may reflect natural progression without an identifiable precipitant; an advanced diseased ventricle may lose reserve through apoptosis, fibrosis, valvular regurgitation and organ dysfunction. The absence of a reversible cause is itself a signal to consider advanced therapies and goals, not an invitation to repeat the same decongestion indefinitely.

Clinical manifestations

The most common presentation is worsening dyspnea, orthopnea, edema and fatigability over several days; the patient may report weight gain, a reduced response to the diuretic, abdominal tightness, early satiety and nocturia. The time course must be reconstructed precisely: minutes suggest arrhythmia, ischemia, hypertensive crisis or acute valvular disease; weeks suggest progressive accumulation and chronic deterioration. In acute pulmonary edema, intense air hunger, tachypnea, accessory muscle use, sweating, agitation, hypoxemia and diffuse crackles develop rapidly. Pink, frothy sputum indicates alveolar edema but is not necessary for diagnosis; the patient tends to remain seated and cannot tolerate lying down; fatigue, reduced consciousness or absent breath sounds signal imminent exhaustion. Blood pressure may be very high in hypertensive edema, normal in conventional congestion or low in shock. Tachycardia is frequent but nonspecific; an extremely high or low heart rate may be the precipitant. Normal saturation with supplemental oxygen does not quantify the work of breathing, which is why respiratory rate, speech, posture, arterial blood gases and ventilatory fatigue remain essential.

Right-sided congestion produces jugular venous distension, hepatojugular reflux, edema, ascites, hepatomegaly and abdominal pain. Nausea, anorexia and reduced intake may predominate. Severe acute right-sided failure causes hypotension and low cardiac output with clear lungs; automatic administration of large fluid volumes may worsen right ventricular dilation and ischemia. Signs of hypoperfusion include cold extremities, mottling, prolonged capillary refill, a weak pulse, oliguria and altered mental status; pulse pressure may narrow. Lactate may be normal in the early stages or rise because of catecholamines, seizures, liver failure and beta-agonists; it must be interpreted and repeated, not used as the sole criterion for shock. Chest pain or pressure points toward ischemia, dissection, embolism or myocarditis; a coronary syndrome may present without pain, especially in patients with diabetes, older people and women, with dyspnea, nausea or shock alone. An ECG must be obtained promptly and repeated if symptoms persist, because an initially nondiagnostic tracing does not rule out dynamic ischemia.

Palpitations, sudden onset and an irregular pulse suggest atrial fibrillation; syncope or presyncope increases suspicion of ventricular arrhythmia, conduction block, embolism or aortic stenosis. A documented arrhythmia does not automatically prove causality: it may be a consequence of hypoxemia, abnormal potassium or adrenergic activation; the temporal relationship between rhythm and hemodynamic deterioration guides the choice between cardioversion and treatment of the underlying context. Fever, chills, productive cough, dysuria or localized pain support infection, but older and immunocompromised patients may present only with delirium or hypotension. Focal crackles, consolidation on ultrasound and dynamic air bronchograms point toward pneumonia, while diffuse, symmetrical B-lines support edema; the two conditions may coexist and require parallel treatment. Signs of acute valvular regurgitation include a new murmur, sudden edema, shock and a hyperdynamic precordium, but the murmur may be short or barely audible when pressures equalize rapidly. A new murmur after myocardial infarction should raise suspicion of papillary muscle or septal rupture. Urgent echocardiography is more reliable than murmur intensity.

In tamponade, jugular venous distension, tachycardia, hypotension and pulsus paradoxus may be accompanied by muffled heart sounds; the classic triad has low sensitivity. In dissection, tearing pain, pulse asymmetry, a neurological deficit or aortic regurgitation are suggestive but not universal; the absence of traditional signs does not reduce the probability of a mechanical emergency to zero. Pulmonary embolism may present with sudden dyspnea, pleuritic pain, syncope, hypoxemia, tachycardia and right-sided signs. Bilateral peripheral edema does not rule it out; unilateral venous thrombosis increases suspicion. Diffuse crackles and cardiomegaly point more toward left-sided heart failure, but overlapping findings require a pathway based on clinical probability; spontaneous urine output may decrease, but an apparently preserved volume does not guarantee adequate natriuresis. Very dilute urine under vasopressin antagonism or osmotic diuresis may remove water without sodium. Fluid balance is subject to measurement errors; weight, urinary sodium and clinical signs complete assessment of the renal response.

Confusion and drowsiness result from hypoperfusion, hypoxia, hypercapnia, sepsis, drugs, uremia or sodium abnormalities. Agitation may express hypoxia rather than simple anxiety. Sedatives and opioids administered without correcting ventilation and perfusion may precipitate respiratory depression, making level of consciousness a vital parameter for serial assessment. Oliguria, jaundice, mottled extremities and rising lactate indicate multiorgan involvement. Disproportionate abdominal pain may signal mesenteric ischemia; very high aminotransferases may signal hypoxic injury; rising creatinine with an active urinary sediment may indicate concomitant kidney disease; the syndrome must not be treated as isolated from the rest of the body. The warm-wet profile combines congestion and preserved perfusion and is the most common; warm-dry may describe a compensated or already treated patient. Cold-wet combines the greatest complexity, because decongestion must proceed without worsening perfusion; cold-dry requires distinguishing low preload from severe failure without elevated pressures.

Killip class remains useful in myocardial infarction: absence of heart failure, crackles/S3, pulmonary edema and shock describe increasing severity; the SCAI classification stratifies shock from at risk to extremis and considers deterioration over time. These scales do not replace individual physiology but improve communication, triage and shock team activation. Older patients may present with loss of independence, a fall, delirium or poor appetite. COPD, obesity and kidney disease modify signs and biomarkers; baseline chronic edema makes comparison with the usual state important. Caregivers and previous records help establish the change from baseline. A rapid response to nitrates, positive pressure or diuretics supports but does not prove the diagnosis, because dyspnea and blood pressure may improve for many reasons. Treatment must not be delayed in a severe presentation, but etiological reassessment must continue even after symptoms resolve.

In a predominantly abdominal exacerbation, ascites, hepatomegaly, intestinal edema and increased abdominal circumference sometimes precede dyspnea; the patient may lose appetite and drink less while remaining congested, creating an apparent contradiction between reduced intake and overload. Cheyne-Stokes breathing may become more pronounced during congestion, with phases of hyperventilation and central apnea; its observation while awake suggests advanced ventilatory instability, but sedatives, opioids and neurological lesions must be excluded. The primary treatment is appropriate cardiac and respiratory stabilization. Very high jugular venous pressure without edema may reflect a rapid increase; massive edema with jugular veins that are difficult to assess may reflect obesity or partial treatment. Kussmaul’s sign points toward right-sided failure, constriction or restriction. Physical signs remain useful when assessment is repeated after interventions.

The presence of hypertension does not guarantee stability; a patient with edema and a blood pressure of 200 mmHg may deteriorate rapidly because of fatigue, ischemia or an abrupt pressure reduction. Conversely, a value of 90 mmHg may be usual in advanced HFrEF and compatible with perfusion; comparison with baseline and organ signs defines risk. Mottling is assessed at the knees and may be graded; capillary refill time is influenced by temperature and technique. These peripheral signs, together with central-to-peripheral temperature differences and urine output, provide repeatable perfusion monitoring and may change before blood pressure does. A third heart sound suggests elevated pressures and dysfunction, but tachycardia and environmental noise reduce its detection; a new or changed murmur must be correlated with instability. Ultrasound does not make auscultation obsolete: an unexpected finding may accelerate investigation for a mechanical complication.

The amount of edema does not quantify intravascular volume. Sepsis, hypoalbuminemia and vasodilation may coexist with peripheral edema and insufficient arterial filling, while severe venous congestion may coexist with low blood pressure; treatment must distinguish compartments and not apply the simple equivalence edema equals hypervolemia. The initial response must be documented in concrete terms: reduced respiratory rate, improved speech, blood pressure, oxygen saturation, urine output and perfusion; a patient who “feels better” but remains tachypneic or hypoperfused needs further observation. Subjective relief is important but is not the only endpoint.

Investigations and diagnosis

Initial assessment follows airway, breathing and circulation, with monitoring, venous access, repeated blood pressure measurements, oxygen saturation, temperature and mental status. Respiratory distress, shock, unstable arrhythmia and mechanical causes must be recognized within minutes; the essential history includes onset, pain, heart disease, medications, the usual diuretic, anticoagulants, renal function, allergies and advance directives. The 12-lead ECG identifies ischemia, rhythm, conduction and hypertrophy. ST-segment elevation, ischemic equivalents or unstable arrhythmias activate specific pathways; a known bundle branch block should be compared with previous tracings. Telemetry is indicated in hospitalized patients at risk, but alarms and artifacts must be verified before intervention; blood gas analysis is not mandatory for every case of stable congestion, but is useful with respiratory distress, hypoxemia, suspected hypercapnia, shock or ventilation. Respiratory alkalosis is frequent initially; a normal or elevated PaCO2 in severe tachypnea may indicate fatigue. Metabolic acidosis and lactate provide information about perfusion, while a venous sample may suffice for pH and trends in many settings.

BNP below 100 pg/mL or NT-proBNP below 300 pg/mL in the acute setting makes heart failure less likely, but does not rule it out in obesity, very early edema or specific forms. Elevated values support cardiac stress without distinguishing acute from chronic disease. Age, atrial fibrillation and renal function shift the distributions; rule-in thresholds must be interpreted together with pretest probability; high-sensitivity troponin is measured to identify myocardial infarction and stratify risk. A rise and/or fall in troponin with at least one value above the sex-specific 99th percentile URL, when attributable to ischemia and accompanied by the appropriate diagnostic criteria, meets the criteria for myocardial infarction; dynamic changes without ischemia indicate acute nonischemic myocardial injury, while persistently elevated values in a stable clinical context may indicate chronic myocardial injury. Heart failure, sepsis, embolism and tachycardia are frequent causes, and coronary angiography is not automatic for every positive result. Complete blood count, sodium, potassium, chloride, bicarbonate, urea, creatinine, glucose, magnesium and liver function tests are generally necessary. TSH, ferritin, transferrin saturation, serum digoxin, toxicology tests, cultures and procalcitonin depend on the suspected diagnosis; low chloride and alkalosis may indicate intense activation and diuretic resistance; tests must be serial during treatment.

Chest radiography looks for edema, effusions, cardiomegaly and alternative diagnoses. Redistribution, peribronchial cuffing, Kerley B-lines and perihilar opacities describe stages of congestion, but sensitivity is limited and a supine examination is more difficult. Radiographically clear lungs do not rule out elevated pressures, especially in right-sided failure or very early edema. Lung ultrasound shows multiple, diffuse, bilateral B-lines, a generally thin and regular pleural line, and may show effusions; consolidations are not typical except for compressive atelectasis from a large effusion. A reduction in B-lines during treatment may document decongestion; focal lines or a markedly abnormal pleura point toward pneumonia or interstitial lung disease; technique, number of zones and position must be consistent for comparisons. Point-of-care echocardiography assesses global function, the right ventricle, effusion, the vena cava and major abnormalities; it does not replace a comprehensive examination when valvular quantification and advanced decisions are needed. In shock or a suspected mechanical cause, it must be performed immediately. Technically difficult images may be improved with contrast and transesophageal echocardiography.

Comprehensive assessment defines ejection fraction and volumes, regional wall motion, valves, prostheses, pressures, the pericardium and proximal aorta; preserved ejection fraction during edema does not rule out severe failure; stroke volume and the velocity-time integral may reveal low cardiac output. A hyperdynamic ventricle may indicate vasoplegia, hypovolemia or severe regurgitation, not necessarily normal function. In acute mitral regurgitation, an eccentric jet, flow convergence and systolic flow reversal in the pulmonary veins help diagnosis, but conventional quantitative measurements may be unstable. In a post-infarction septal defect, color Doppler and the gradient identify the shunt; in free-wall rupture, an effusion with clots and collapse requires surgery; an early negative examination may need to be repeated if the clinical picture changes. Pulmonary CT angiography is performed according to probability and stability; D-dimer is useful mainly for ruling out embolism at low to intermediate probability, with age adjustment when appropriate. In shock when transport is impossible, echocardiography and venous ultrasound may support an urgent decision, but right ventricular dilation is not specific to embolism.

Aortic CT is indicated when acute aortic syndrome is suspected; transesophageal echocardiography is an alternative in unstable patients or in the operating room; the ADD-RS score and D-dimer may help in selected populations but do not override a high clinical probability. Renal function must not delay potentially lifesaving imaging. Urgent coronary angiography follows the indications for coronary syndrome, ischemic shock and complications. In post-infarction shock, immediate revascularization of the culprit lesion is central; indiscriminate immediate multivessel intervention may increase harm and is distinguished from staged revascularization. Anatomy, viability and goals guide management of patients with heart failure without acute ischemia; spot urinary sodium approximately two hours after the diuretic and hourly urine output provide early feedback. Low natriuresis or insufficient urine output suggests the need for rapid dose intensification, while checking blood pressure and the diagnosis. Urinary sodium is influenced by timing, renal function and previous diuretics and must not be interpreted without the overall fluid balance.

Daily weight and fluid intake and output are useful but subject to errors. A urinary catheter is not necessary in every patient and increases infections; it is reserved for shock, retention, precise monitoring or practical inability to measure output otherwise. Creatinine must be interpreted together with blood pressure, urine output, congestion and urinary sediment, avoiding defining success by renal stability alone. Right heart catheterization is indicated in shock, refractoriness, discordance about volume status, suspected pulmonary hypertension or assessment for mechanical support. Right atrial pressure, wedge pressure, cardiac output, cardiac power output and pulmonary artery pulsatility index describe phenotypes, but no threshold is perfect; measurement must be performed and interpreted by an experienced team. An elevated wedge pressure with preserved cardiac output supports left-sided congestion; disproportionately high right-sided pressure suggests right ventricular failure; low pressures with reduced cardiac output point toward hypovolemia or insufficient preload. Prominent v waves may indicate mitral regurgitation; positive-pressure ventilation and PEEP modify intrathoracic pressures, requiring measurements at end-expiration and contextual interpretation.

Severity is stratified using blood pressure, renal function, sodium, troponin, peptide levels, lactate and comorbidities. Scores such as ADHERE, OPTIMIZE-HF and MAGGIC help describe risk, but do not determine the ward on their own. A need for ventilation or vasopressors, arrhythmias, coronary syndrome and rapid deterioration indicate an intensive care setting; the diagnosis of heart failure must be reassessed if there is no consistent response. ARDS, pneumonia, COPD, embolism, renal failure with overload, cirrhosis and anemia may mimic or accompany the presentation; multiple diagnoses are common in older patients and often explain a partial response to a single treatment. Before discharge, the etiology, precipitant, ejection fraction, congestion status, renal function, rhythm, iron status, treatment and plan must be documented. Jugular venous pressure, orthopnea, edema and the oral diuretic dose must be reassessed after the transition from intravenous therapy. A patient who develops recurrent congestion during observation is not ready for discharge merely because oxygen saturation is normal.

Orthostatic measurements are obtained after stabilization in patients with falls, dizziness or vasodilator treatment; marked orthostatic hypotension may indicate depletion, autonomic neuropathy or drug effects even when edema persists. This finding modifies titration and discharge risk; procalcitonin may help when the diagnosis of bacterial infection is uncertain, but renal dysfunction and noninfectious inflammation alter its values. Blood cultures precede antibiotics in sepsis or suspected endocarditis if this does not cause delay. A single biomarker must neither mandate nor prohibit antimicrobial therapy. Serum digoxin is interpreted in relation to the time of the last dose; sampling too early reflects distribution and overestimates the tissue level. High potassium in acute toxicity and low potassium in chronic toxicity modify risk. Renal insufficiency, amiodarone, verapamil and macrolides increase exposure, making the medication history part of the test.

Ketones and beta-hydroxybutyrate are assessed in patients taking SGLT2 inhibitors who have nausea, acidosis or fasting, even if blood glucose is not elevated; euglycemic ketoacidosis may mimic hypoperfusion and requires insulin, glucose and cautious fluids. The SGLT2 inhibitor is discontinued and the precipitating cause treated; compression venous ultrasound identifies thrombosis and may support a diagnosis of embolism when CT is impossible. Portal, hepatic and renal Doppler and VExUS describe organ venous congestion, but are influenced by rhythm, respiration and valves. These tools are complementary and do not yet have a role as a sole endpoint for diuresis. Thoracic or whole-body bioimpedance may estimate fluid changes, but the device, body composition and effusions interfere. A trend may be more useful than the absolute value. Its use must be linked to validated decisions and must not delay clinical examination or ultrasound.

Intra-abdominal pressure may increase in ascites and visceral edema, reducing renal perfusion and venous return. Bladder pressure measurements are reserved for critically ill patients with suspected intra-abdominal hypertension. Paracentesis may relieve pressure in selected cases, but requires analysis of ascitic fluid when the etiology is not clearly cardiac. Low ScvO2 or SvO2 indicates high extraction relative to cardiac output, but depends on hemoglobin, oxygen consumption and catheter location; in sepsis, these values may be normal or high despite hypoperfusion. Cardiac power output combines blood pressure and cardiac output and has prognostic significance in shock; no index eliminates the need for serial examination. Thermodilution may be less accurate with severe tricuspid regurgitation or a shunt; the estimated Fick method depends on an assumed oxygen consumption that is often incorrect. When decisions about support depend on cardiac output, the technique and limitations must be made explicit. Comparing trends obtained with different methods may create a false change.

In shock, CT of the brain, chest or abdomen and other investigations must be selected by balancing transport risks and usefulness; the patient must not leave a monitored environment without adequate support. Bedside ultrasound may narrow the diagnosis, but must not delay definitive imaging when the correctable cause remains uncertain; risk scores are not tools for automatically ruling out hospital admission. A young patient with myocarditis and arrhythmias may have normal renal tests but high risk; an older patient with stable congestion may be managed in a less intensive area with adequate support. Triage and care setting depend on the potential speed of deterioration. Adherence assessment uses a nonjudgmental conversation, medication pack availability, refills and understanding. “Do you take your medications?” often produces an uninformative answer. Questions about missed doses, costs, effects and the ability to read labels identify modifiable causes and distinguish intentional from unintentional nonadherence.

Treatment and prognosis

Treatment begins simultaneously with diagnosis; the patient is positioned sitting up if tolerated, monitored and assessed for respiratory and circulatory support. The immediately reversible cause is corrected, routine fluid administration is avoided and the blood pressure profile is defined. Each intervention must be followed by prompt reassessment of dyspnea, heart rate, blood pressure, perfusion, urine output and consciousness; oxygen is indicated for hypoxemia, generally with saturation below 90% or PaO2 below 60 mmHg, not routinely in normoxemic patients. An excessive concentration may cause vasoconstriction and hypercapnia in susceptible individuals. Cannulas, masks and high-flow systems are selected according to need; the target must account for COPD with chronic CO2 retention. CPAP or bilevel noninvasive ventilation is started early in edema with respiratory distress, tachypnea and hypoxemia despite oxygen. It reduces work, venous return and afterload and decreases the need for intubation. Hypotension, vomiting, inability to protect the airway, facial trauma or uncontrollable agitation are relative or absolute contraindications. Failure to respond promptly requires intubation, not dangerous prolongation.

Intubation is indicated for exhaustion, refractory hypoxemia, severe acidosis, altered consciousness or instability; induction may cause collapse through loss of sympathetic tone and increased intrathoracic pressure; readiness of a vasopressor, agent selection and preoxygenation are crucial. PEEP and tidal volume must balance oxygenation and venous return, with particular caution in right-sided failure; intravenous loop diuretics are the foundation of treatment for congestion with volume overload. In patients already receiving treatment, an initial dose of approximately one to two and a half times the equivalent daily oral dose is a common strategy; in diuretic-naive patients, the dose is selected according to renal function and severity. The DOSE trial did not show superiority of continuous infusion over boluses, while the more intensive strategy produced greater diuresis with more transient creatinine increases. Response is assessed in the first two to six hours using urine output, symptoms and, when used, urinary sodium. An insufficient response requires rapid dose doubling until the tubular threshold is exceeded, not small, late additions. The daily goal depends on severity and perfusion; net losses of several liters may be appropriate in marked overload, but are not a universal target.

Sequential blockade with a thiazide or metolazone inhibits distal compensation and may overcome resistance, but increases hyponatremia, hypokalemia and worsening renal function. Intravenous acetazolamide 500 mg added to a loop diuretic increased early decongestion in the ADVOR trial in selected patients with volume overload. Bicarbonate, eGFR, blood pressure and the trial criteria guide selective use; hypertonic saline combined with high-dose diuretics has been studied in specific protocols, but is not a generalizable standard therapy. Albumin does not automatically improve the response in every case of hypoalbuminemia and may expand intravascular volume. Tolvaptan corrects water balance and hyponatremia and increases aquaresis, but has not demonstrated a general mortality benefit. Ultrafiltration removes sodium and water in a controlled manner, but CARRESS-HF showed greater creatinine deterioration without better weight loss compared with a pharmacological strategy in cardiorenal syndrome. It is not used routinely; it may be considered for truly refractory congestion despite an adequate diuretic protocol or when there is an indication for dialysis.

Intravenous nitrates are particularly useful in hypertensive edema, reducing preload and, at higher doses, afterload. Nitroglycerin can be titrated rapidly to blood pressure and symptoms; nitroprusside provides potent balanced vasodilation with intensive monitoring. Hypotension, right ventricular infarction and critical aortic stenosis require caution, while recent use of PDE5 inhibitors contraindicates nitrates for the interval specified for the active agent. European guidelines consider intravenous vasodilators when systolic blood pressure is adequate, often above 110 mmHg; reduction during a hypertensive crisis must be rapid but controlled, avoiding a fall that compromises cerebral, renal and coronary perfusion. The blood pressure target depends on baseline, ischemia and the clinical response, not on the same number for everyone; morphine is not recommended routinely. It may reduce anxiety and dyspnea but causes nausea, hypotension and respiratory depression and delays absorption of oral antiplatelet drugs; observational findings associate its use with unfavorable outcomes, with confounding by severity. It may have a selective role in palliation or severe pain with monitoring.

Inotropes are reserved for hypoperfusion with low cardiac output and insufficient blood pressure not corrected by volume or treatment of the cause. Dobutamine stimulates beta-receptors and increases cardiac output but may cause tachycardia and arrhythmias; milrinone inhibits PDE3, reduces pulmonary vascular resistance and does not depend on beta-receptors, but causes hypotension and accumulates in the kidney. Use without hypoperfusion increases arrhythmic risk without benefit. Norepinephrine is generally the preferred vasopressor in hypotensive cardiogenic shock to restore blood pressure, often combined with an inotrope if cardiac output remains low. Epinephrine produces greater tachycardia and lactate elevation and is less favorable in available comparisons; vasopressin may be added in selected cases of vasoplegia. The goal is the lowest dose that ensures organ perfusion. The choice between dobutamine and milrinone considers blood pressure, beta-blockade, renal function, pulmonary vascular resistance and arrhythmias; the DOREMI trial did not show clear superiority of either strategy in the overall shock population. The effect must be documented using perfusion, urine output, lactate and, where appropriate, hemodynamic assessment, and treatment reduced as soon as management of the cause or mechanical support allows.

For the right ventricle, preload, systemic pressure, rhythm and pulmonary afterload are optimized. Hypoxia, hypercapnia, acidosis and high ventilatory pressures increase pulmonary vascular resistance and must be corrected. Inhaled pulmonary vasodilators may selectively reduce afterload as a bridge, without demonstrated routine outcome benefit; excess fluids worsen ventricular interdependence. Mechanical supports include an intra-aortic balloon pump, percutaneous axial or centrifugal pumps, venoarterial ECMO and surgical devices; no device is universally indicated; selection depends on the ventricle involved, oxygenation, the cause, the possibility of recovery or definitive therapy, and complications. Early cannulation may save selected patients, but bleeding, ischemia, hemolysis, stroke and inadequate unloading may negate the benefit. The shock team integrates an intensivist, interventional cardiologist, advanced heart failure specialist and cardiac surgeon. Serial SCAI classification and hemodynamics help recognize deterioration before arrest. Escalation must have a plausible destination, such as recovery, revascularization, surgery, VAD or transplantation; support without an exit strategy may prolong irreversible injury.

In acute coronary syndrome, antiplatelet therapy, anticoagulation and reperfusion are initiated according to guidelines, taking dissection and bleeding into account. In post-infarction shock, PCI of the culprit lesion is the initial strategy; mechanical complications require urgent surgery and support; heart failure treatment accompanies but does not delay revascularization. Tachyarrhythmias with hypotension, ischemia, edema or altered mental status require synchronized cardioversion. If the patient is stable, rate or rhythm control depends on the arrhythmia type, duration, anticoagulation and substrate. In acute HFrEF, verapamil and diltiazem are avoided; digoxin acts slowly and intravenous amiodarone may cause hypotension. Electrolyte abnormalities and precipitants must be corrected. Unstable bradycardia is treated with atropine when appropriate, transcutaneous or transvenous pacing and bridging drugs, while correcting ischemia, hyperkalemia and toxicity. Specific antidotes may be needed for beta-blocker or calcium channel blocker toxicity; pacing must restore rate and synchrony while avoiding prolonged dyssynchrony whenever possible.

Hypertensive crisis, dissection, embolism, tamponade, endocarditis and acute valvular regurgitation follow specific pathways directed at the cause. Early antibiotics are indicated in sepsis after cultures when possible; they are not administered solely for elevated C-reactive protein; removal of a mechanical or infectious cause determines prognosis more than the amount of fluid removed. Chronic treatment should not be automatically discontinued on admission. Beta-blockers are generally continued if there is no shock, bradycardia or severe hypoperfusion; RAAS inhibitors, ARNIs and MRAs are reassessed according to blood pressure, potassium and renal function. A necessary discontinuation must have an explicit plan for reintroduction before or shortly after discharge. Sacubitril/valsartan may be initiated in hospital after hemodynamic stabilization in HFrEF, as supported by PIONEER-HF; blood pressure must be stable, without recent increases in inotropes or vasodilators, and renal function and potassium must be compatible. The 36-hour washout after an ACE inhibitor remains mandatory.

Empagliflozin initiated in hospital after stabilization produced clinical benefit in the EMPULSE trial regardless of ejection fraction and diabetes; SGLT2 inhibitors have a modest blood pressure effect, but require the absence of ketoacidosis, shock, prolonged fasting and severe instability. Instructions must be provided for temporary withdrawal during acute illness. An MRA may be initiated if potassium and glomerular filtration allow; a beta-blocker is started or titrated when the patient is euvolemic and perfused. The goal is not to reach maximum doses during instability, but to establish the four pillars before discharge or through close follow-up; post-hospitalization therapeutic inertia is an important cause of residual risk. Venous thromboembolism prophylaxis is indicated in immobilized hospitalized patients who are not anticoagulated and have an acceptable bleeding risk. Therapeutic anticoagulation requires atrial fibrillation, thrombus, embolism, a prosthetic valve or another indication and does not follow from hospitalization for heart failure alone. Dose and agent must account for renal function, weight, procedures and interactions.

Sodium and fluids are managed individually. Extreme restrictions may increase thirst, malnutrition and activation; fluid restriction is reasonable in dilutional hyponatremia or resistant congestion. Nutrition, protein intake and mobilization should begin after stabilization, because hospitalization accelerates sarcopenia and functional decline; transition from an intravenous to an oral diuretic requires a dose capable of maintaining fluid balance, preferably observed for at least an adequate interval. Bioavailability, renal function and diet modify the equivalent dose; the plan must specify target weight, the usual dose, any agreed adjustment and whom to contact if the response is insufficient. Stability criteria include no need for urgent intravenous treatment, stable blood pressure and rhythm, adequate perfusion, substantial resolution of congestion, manageable renal function and electrolytes, the ability to take medications, and support. Natriuretic peptides may contribute to prognosis, but a mandatory discharge threshold does not replace clinical judgment.

Discharge must include reconciliation, education, an early appointment, scheduled tests and communication with the treating physician. Follow-up within seven days is appropriate for high-risk patients; the STRONG-HF strategy used very frequent visits and titration with monitoring of symptoms, blood pressure, renal function, potassium and NT-proBNP. Its application requires the same conditions of selection and surveillance. Poor prognostic indicators include low blood pressure, lactate, blood urea, creatinine, hyponatremia, troponin, elevated peptide levels, right ventricular dysfunction, residual congestion, recent hospitalizations, cachexia and inability to take therapies. Age alone does not determine futility; the trajectory, reversibility of the cause and previous function must inform intensive care decisions. In patients with recurrent episodes despite therapy, evaluation for advanced heart failure must take place before multiorgan failure. Dependence on inotropes, escalating diuretics, hypotension, hospitalizations and drug intolerance are referral signals. At the same time, palliative care controls dyspnea and anxiety and supports decisions consistent with personal goals.

The diuretic response must be considered in terms of sodium, not only urine; a patient with abundant urine output but low natriuresis may lose water and develop hyponatremia without correcting total body sodium. An early spot sample, reliable weights and fluid balance allow intensification before clinical resistance develops. When the response remains insufficient, it is verified that the drug has actually been administered and that there is no hypotension, urinary obstruction or incorrect diagnosis. The loop diuretic dose, distal combination and perfusion are corrected. Low-dose dopamine did not improve decongestion or renal function in the ROSE-AHF trial and is not a routine renal strategy. Potassium is generally maintained within a safe range, often above 4 mmol/L in patients with arrhythmias, and magnesium is corrected; supplementation must account for MRAs, renal function and rapid changes in urine output. A protocol prevents both inadequate replacement and hyperkalemia from accumulation.

Hypotonic hyponatremia requires distinguishing congestive dilutional hyponatremia, diuretic-induced depletion and other causes. In the dilutional form, congestion and free water are addressed; in depletion, reducing diuretics and restoring volume may be necessary. Hypertonic saline is reserved for severe neurological symptoms with controlled correction; atrial fibrillation of unknown duration in a stable patient is not cardioverted without assessing thrombus and anticoagulation, except when instability makes intervention urgent. Transesophageal echocardiography or adequate anticoagulation reduces embolic risk. After cardioversion, the substrate is treated, because persistent congestion promotes rapid recurrence. In right ventricular infarction, nitrates and diuretics may excessively reduce preload; a cautious fluid challenge may improve cardiac output if pressures are not already high. Reperfusion and sinus rhythm are central. Persistent low cardiac output requires an inotrope and sometimes right ventricular support.

In edema caused by acute mitral regurgitation, vasodilation and intra-aortic balloon counterpulsation may reduce regurgitation as a bridge if blood pressure allows, but mechanical correction is definitive. The patient may have an apparently high ejection fraction because part of the stroke volume enters the atrium; forward stroke volume is reduced. In critical aortic stenosis, tachycardia, vasodilation and hypovolemia are poorly tolerated; diuretics are used cautiously and urgent valve correction may be necessary. Balloon valvuloplasty may serve as a bridge in selected patients, while TAVI or surgery depends on anatomy and the shock team. In thyroid storm, beta-blockade reduces adrenergic activity but may precipitate collapse in low-output states; short-acting drugs and monitoring are preferable. Antithyroid drugs, iodine in the correct sequence, corticosteroids and treatment of the precipitant are combined; the high-output physiology makes diuresis alone insufficient.

In acute peripartum cardiomyopathy, hydralazine and nitrates may replace RAAS inhibitors during pregnancy, and selected beta-blockade is used cautiously. Anticoagulation is considered with a very low ejection fraction, thrombus or bromocriptine according to protocols; delivery is planned by a team and is not automatically by cesarean section. Severe anxiety in edema often improves with ventilation and pressure reduction. Communication, the team’s presence and a well-fitting mask facilitate NIV. Benzodiazepines may depress respiration and increase delirium; selected light sedation requires monitoring and must not mask ventilatory failure. After the critical phase, mobilization includes sitting, standing and walking with blood pressure and symptom monitoring; orthostatic hypotension and weakness may require physiotherapy. A pathway that waits until discharge day to test walking discovers significant disability too late.

Intravenous iron may be administered after stabilization in patients who meet the criteria for deficiency, improving quality of life and reducing hospitalizations in studies. It is not a treatment for the shock phase or uncontrolled infection; oral iron does not effectively correct many deficiencies in heart failure. Selection of the maintenance diuretic dose considers the pre-admission dose, response and new dry weight; a lower dose may suffice after optimization of ARNI and SGLT2 therapy; a higher dose may be necessary with renal impairment or persistent congestion. The plan must provide for laboratory monitoring within a few days when risk is high. Prognosis may improve substantially if the precipitant is reversible and therapies are implemented. A single hospitalization does not inevitably define terminal disease; repeated episodes and progressive intolerance instead signal a trajectory. Communicating this distinction supports both adherence and realistic planning.

Complications

Respiratory failure may progress despite oxygen and diuretics, requiring ventilation. Late intubation increases periprocedural arrest; unnecessary intubation exposes the patient to pneumonia, delirium and instability. Pneumothorax, aspiration and superimposed ARDS must be investigated when oxygenation does not improve as expected; cardiogenic shock may evolve from an initially compensated profile to hypotension, lactate elevation and multiorgan failure. Vasopressors maintain blood pressure but increase ischemia and arrhythmias; inotropes increase oxygen consumption; failure to correct myocardial infarction, valvular disease or tamponade makes pharmacological support a temporary measure rather than a solution. Cardiac arrest may result from ventricular fibrillation, tachycardia, asystole or pulseless electrical activity. Ischemia, hypoxia, acidosis and potassium abnormalities are reversible causes; tamponade, pulmonary thrombosis and coronary thrombosis must be considered. After return of circulation, post-arrest treatment is integrated with management of heart failure and its cause.

Worsening renal function may require medication changes, but indiscriminate withdrawal of decongestion leaves venous pressure elevated. Severe hyperkalemia, acidosis, uremia, refractory overload and some poisonings are indications for renal replacement therapy; continuous treatment is often better tolerated in instability, without being intrinsically superior in every patient. Diuresis-induced hypokalemia, hypomagnesemia and alkalosis increase arrhythmias and resistance; hyponatremia reflects vasopressin and free water; hyperkalemia results from renal dysfunction and drugs; corrections must consider rate and distribution. A hemolyzed sample may simulate hyperkalemia and should be checked if there are no electrocardiographic signs or supporting context. Hypoxic liver injury combines a marked increase in AST and ALT, lactate elevation and coagulopathy after hypotension or low cardiac output, but may also occur without a documented hypotensive episode. Chronic congestion increases vulnerability. Treatment consists of restoring perfusion and reducing congestion, avoiding hepatotoxic drugs and recognizing an independent hepatic cause.

Mesenteric ischemia and intestinal infarction are promoted by low cardiac output, vasopressors and atherosclerosis. Pain, distension, blood in the stool and rising lactate are late or nonspecific findings; CT angiography and surgery must not be delayed; more common intestinal edema may instead cause ileus and reduced drug absorption. Delirium results from hypoxia, hypoperfusion, infection, drugs, sleep deprivation and the intensive care environment. It increases falls, aspiration and length of stay. Correction of causes, orientation, family presence, mobilization and reduction of catheters are preferable to sedation; antipsychotics carry QT-related risks and do not treat the cause. Venous thromboembolism is promoted by stasis and immobility; bleeding increases with renal insufficiency, anticoagulants, procedures and hepatic congestion. Occult bleeding may be the anemic precipitant of heart failure. Prophylaxis and treatment must be reassessed daily in relation to bleeding risk.

Healthcare-associated infections include pneumonia, urinary tract infection and line-associated bacteremia. Arterial, venous and urinary catheters must have an indication and be removed as soon as possible. Fever in a patient with an intracardiac device requires consideration of endocarditis and lead infection; incomplete decongestion is a more common treatment complication than symptom improvement suggests. The lungs may clear while elevated jugular venous pressure and organ congestion persist; stable creatinine does not offset the high risk of discharge while still wet. Conversely, overdiuresis causes orthostatic hypotension, syncope, kidney injury and neurohormonal activation. A patient with right ventricular disease, aortic stenosis or constriction may be particularly preload-dependent. Weight below the true dry weight, intense thirst and vena cava collapse must be interpreted together, not automatically.

Complications of vasodilators include hypotension, headache and, with prolonged or high-dose nitroprusside in renal/hepatic insufficiency, cyanide or thiocyanate toxicity. Nitrates develop tolerance and interact with PDE5 inhibitors; invasive monitoring may be necessary for potent drugs in shock. Inotropes and vasopressors may cause peripheral ischemia, arrhythmias, lactate elevation and extravasation injury; an increasing requirement indicates progression and requires reassessment of the cause and support. Continuing an inotrope without an explicit goal may turn a bridge into unplanned chronic dependence. Mechanical support exposes patients to hemolysis, thrombosis, bleeding, limb ischemia, infection and stroke; ECMO increases left ventricular afterload and may require unloading. Ventricular distension and pulmonary edema during ECMO do not indicate failure of oxygenation, but a physiology requiring decompression.

One post-discharge complication is unintentional treatment interruption because of discrepancies between the old medication list, discharge letter and prescriptions. Incorrect diuretic doses, duplicate RAAS therapy or failure to resume beta-blockade cause avoidable events; contact with the patient, pharmacy and treating physician within a few days detects these errors. Even brief hospitalization causes muscle loss, especially with bed rest, inflammation and poor intake. In older patients, this may lead to new dependence even after cardiac compensation. Physiotherapy, adequate protein intake and mobilization after stabilization are part of preventing acquired disability. Recurrent hospitalizations, a need for inotropes, hypotension and organ dysfunction may indicate transition to advanced heart failure; late assessment may preclude transplantation or a VAD because of irreversibility. When advanced therapies are not appropriate or possible, a palliative plan prevents unwanted burdensome interventions.

Early death may result from the precipitating cause; later death may result from progression or a new exacerbation; risk remains high even when ejection fraction is preserved and dyspnea has resolved. A technically correct discharge without access to medications, tests and follow-up leaves the determinants of recurrence unchanged; limb ischemia may result from shock, vasopressors, emboli or support cannulas. Pulses, temperature, color, pain and local lactate must be checked; a distal perfusion cannula does not eliminate risk. Delay may lead to compartment syndrome, rhabdomyolysis and amputation. Rhabdomyolysis may follow hypoperfusion, immobility, ischemia or drugs and worsen hyperkalemia and kidney injury. Creatine kinase, urine and potassium guide diagnosis. The usual aggressive fluid expansion must be adapted to heart failure, sometimes requiring renal replacement therapy.

Disseminated intravascular coagulation may complicate shock, sepsis and mechanical support, with simultaneous thrombosis and bleeding. Platelets, fibrinogen, D-dimer and coagulation times track its course; the main treatment is correction of the cause and use of blood components according to bleeding and procedures. Stress hyperglycemia is associated with severity, while iatrogenic hypoglycemia causes arrhythmias and neurological injury. Intravenous insulin is used in critically ill patients with moderate targets, avoiding excessively tight control. An SGLT2 inhibitor is not started until the patient is stabilized and eating. Pressure injuries develop rapidly in shock, edema and immobility. Pressure-relieving surfaces, position changes compatible with hemodynamics and skin care are preventive; a prone patient or one with devices requires checks of pressure points and lines.

Dysphagia after intubation, stroke or delirium increases aspiration and prevents correct medication intake; swallowing assessment precedes an unrestricted diet in patients at risk. Modified-release tablets must not be crushed without verification, and alternative formulations must respect pharmacology; insomnia, noise and repeated blood sampling worsen delirium and adrenergic activation. Organizing nighttime care, treating orthopnea and reducing unnecessary interventions improve recovery. Automatic use of hypnotics increases falls and respiratory depression, especially after discharge. Early recurrence may be due to unrecognized progression, residual congestion, an ineffective oral dose, lack of access to medications or delayed follow-up. Analysis of the episode must not be limited to labeling it “noncompliance”. Every new hospitalization requires a review of the causes and of eligibility for advanced strategies.