Prosthetic valve dysfunction

Article written and reviewed by Dr Luca Moretti

Prosthetic valve dysfunction is an impairment of the device’s ability to open, close or remain stably anchored, resulting in obstruction, regurgitation or a combination of both. It does not identify a single disease but a hemodynamic syndrome that may result from thrombus, infection, deterioration of biological tissue, pannus overgrowth, dehiscence, malposition, mismatch or interference with cardiac structures. Identifying the mechanism is essential because a treatment that is effective for one cause may be useless or even dangerous for another.

Diagnosis is more complex than for native valves because each prosthetic model has its own effective orifice area, normal washing jets and characteristic artifacts. A small prosthesis may therefore have a relatively high gradient from the time of implantation without being pathological, whereas severe regurgitation may develop while gradients remain normal. Comparison with the baseline echocardiogram obtained under stable conditions is therefore an integral part of the diagnosis, not merely a documentation detail.

The clinical presentation ranges from an incidental finding to pulmonary edema, shock, systemic embolism or destructive endocarditis, and chronology provides valuable information about the mechanism. An abnormality present immediately after the procedure suggests mismatch, malposition or leak, a rapid increase in gradient points toward thrombosis, and progression over several years in a bioprosthesis makes structural degeneration more likely. These associations guide the investigation but must be confirmed by multimodality imaging.

A rigorous assessment answers four questions in sequence: is the prosthesis truly dysfunctional, is the defect obstructive or regurgitant, what mechanism is responsible, and what consequences has it already caused. Only then is it appropriate to decide whether to observe, correct hemodynamic factors, anticoagulate, treat infection or proceed to surgery or a transcatheter intervention.

Classification, mechanisms and clinical presentation

Modern definitions distinguish structural degeneration, meaning a permanent intrinsic abnormality of the leaflets or supporting structure of a bioprosthesis, from reversible or extrinsic causes. Calcification, fibrosis, tearing and flail belong to the first category, whereas thrombosis and endocarditis are separate entities and leak, mismatch, frame underexpansion and malposition fall under non-structural dysfunction. This distinction prevents, for example, an intact valve obstructed by thrombus from being labeled “degenerated”.

In mechanical prostheses, obstruction is caused mainly by thrombus, pannus or a combination of the two. Thrombus can form rapidly in the setting of inadequate anticoagulation and may have a mobile component, whereas pannus is fibroproliferative tissue that grows more slowly from the sewing ring until it restricts the occluder; location, CT density and chronology therefore help distinguish them. Endocarditis, dehiscence and interference from sutures or subvalvular structures complete the differential diagnosis.

In surgical and transcatheter bioprostheses, obstruction may be caused by thrombotic leaflet thickening, structural calcification or fibrosis, frame underexpansion or mismatch. Regurgitation may be intraprosthetic because of leaflet retraction or tearing, paravalvular because of incomplete sealing or dehiscence, or mixed. New mild central regurgitation does not have the same significance as a severe eccentric jet associated with a flail leaflet.

Symptoms depend on valve position, severity and especially the rate of onset. Slowly progressive prosthetic aortic stenosis may present with exertional dyspnea, angina or syncope, whereas acute mitral regurgitation may cause pulmonary edema while the ventricle is still not dilated, and right-sided prostheses more typically cause systemic congestion, ascites and low output. Dyspnea nevertheless remains nonspecific and should be assessed against anemia, coronary artery disease, arrhythmias, pulmonary disease and ventricular dysfunction.

Cerebral or peripheral embolism may precede hemodynamic manifestations in both thrombosis and endocarditis. Fever, chills, weight loss, splenomegaly or vascular phenomena strengthen suspicion of infection, although they may be absent in older or immunocompromised patients; hemolysis, by contrast, presents with fatigue, jaundice, dark urine or transfusion requirement and is particularly typical of high-velocity paravalvular jets, although it is not exclusive to this mechanism.

Examination looks for changes in mechanical clicks, a new murmur, signs of heart failure and stigmata of endocarditis. An apparently normal click does not exclude immobility of one of two hemidiscs; a soft murmur does not exclude severe acute regurgitation when pressures equalize. ECG, chest radiography, complete blood count, creatinine, bilirubin, lactate dehydrogenase, haptoglobin and reticulocytes complete the assessment; multiple blood cultures should be obtained before antibiotics if the patient is stable.

The clinical trajectory defines urgency. Shock, hypoxemia, pulmonary edema, recurrent syncope, ongoing embolization or suspected complicated endocarditis require immediate evaluation, whereas a stable patient with a gradual increase in gradient can follow a rapid but scheduled pathway. In all cases, the label of “mild dysfunction” should not precede assessment of ventricular consequences and serial trend.

Echocardiography: baseline comparison and hemodynamic analysis

Transthoracic echocardiography is the starting point. The report identifies the valve position, model and size of the prosthesis, records heart rate, blood pressure and flow state, and evaluates chambers, ventricular function, pulmonary pressure and other valves. For an aortic prosthesis, peak velocity, mean gradient, Doppler velocity index, effective orifice area and acceleration time are recorded; for a mitral prosthesis, the mean gradient at the reported heart rate, pressure half-time with caution, and regurgitation are assessed.

A high gradient alone does not prove obstruction because anemia, fever, pregnancy, fistulas, sepsis, tachycardia or significant regurgitation increase flow, and a small prosthesis may be physiologically more resistive. Measurement technique also affects the value: Doppler misalignment tends to underestimate it, whereas inclusion of locally accelerated flow may overestimate it. Because left ventricular outflow tract diameter is squared in the calculation of area, even a small error may produce a relevant difference.

The morphology of the Doppler envelope adds information beyond the simple gradient measurement. In a normally functioning aortic prosthesis, the peak tends to occur early and acceleration time is short, whereas fixed obstruction more often produces a rounded, late-peaking profile; DVI and the ratio of acceleration time to ejection duration also reduce dependence on outflow tract measurement. These indices must, however, be interpreted concordantly and always compared with baseline.

In mitral and tricuspid prostheses, the gradient depends markedly on heart rate, diastolic interval and flow, so a value obtained during tachycardia cannot be compared directly with a baseline recorded at a slow rate. Area derived from pressure half-time is also affected by atrial and ventricular compliance and should not dominate assessment; in the pulmonary position, finally, interrogation from multiple windows and evaluation of the right ventricle are essential.

Regurgitation must be distinguished as intraprosthetic or paravalvular. In mechanical valves, small washing jets with characteristic location, direction and duration are physiological, whereas pathological regurgitation is new, larger or associated with an occluder abnormality; shadowing and reverberations may nevertheless obscure jets, especially in the mitral position. Assessment should therefore integrate continuous-wave Doppler density, flow convergence, vena contracta, venous flows and chamber consequences.

Transesophageal echocardiography, preferably three-dimensional, allows visualization of leaflets, masses, dehiscence and jet origin when transthoracic imaging is insufficient and is particularly useful for mitral prostheses, endocarditis and planning paravalvular leak closure. This modality too, however, may be affected by artifacts, requires sedation and does not always distinguish thrombus from pannus with certainty, so the result must be integrated with the clinical picture, Doppler and CT.

Stress echocardiography can clarify discordant symptoms, contractile reserve and gradient behavior in selected patients, but it is not appropriate in the presence of instability or a high-risk mobile mass. Because gradient rises physiologically with flow, its increase during exercise does not by itself prove obstruction; the test becomes valuable when it reproduces symptoms and documents a hemodynamic response consistent with the clinical picture.

The quality of serial comparison depends largely on availability of the post-implant examination, which should be retrieved in full rather than replaced by the simple statement “normally functioning prosthesis”. An increase from baseline associated with a reduction in area or DVI is much more informative than a single value above a generic reference interval. If baseline data are unavailable, expected values for the specific model and size can help, but they do not reconstruct the individual patient’s physiology.

CT, fluoroscopy and multimodality differential diagnosis

When the mechanism remains uncertain, anatomical imaging complements Doppler information. Cinefluoroscopy, for example, records the opening and closing angles of mechanical occluders without acoustic interference and can demonstrate an immobile or hypomobile disc; however, it does not reliably identify the tissue responsible for obstruction and does not assess regurgitation or cardiac consequences. It nevertheless remains a rapid and useful modality in emergencies when immediately available.

Gated cardiac CT visualizes leaflet excursion, frame, annulus, calcification and masses and, in mechanical valves, may help distinguish dense pannus adherent to the sewing ring from thrombotic material, which is generally lower in attenuation and bulkier. Attenuation thresholds are only a guide, however, because they depend on technique and lesion composition and do not replace integrated assessment, especially in mixed forms.

In bioprostheses, four-dimensional CT is particularly sensitive for hypoattenuated leaflet thickening and reduced leaflet motion, findings compatible with subclinical or clinical thrombosis. Calcification, tearing, deformation and underexpansion instead suggest different mechanisms; the same modality also allows valve-in-valve planning, estimation of coronary risk, measurement of the true internal diameter and, in the mitral position, prediction of possible left ventricular outflow tract narrowing.

Metal artifacts, irregular heart rate, renal impairment and radiation burden may limit CT and require protocols tailored to the device and patient. Cardiac magnetic resonance provides different information, useful mainly for quantifying volumes and regurgitation when echocardiography is inconclusive, provided compatibility and artifacts permit; it is not the first-line modality for studying mechanical disc motion. Examination choice should therefore answer a specific clinical question.

When prosthetic valve endocarditis is suspected, transesophageal echocardiography, CT and fluorodeoxyglucose PET/CT provide complementary information on vegetations, abscesses, pseudoaneurysms, dehiscence and metabolic activity. Early uptake after surgery may, however, reflect sterile inflammation and requires interpretive expertise, while blood cultures and clinical criteria remain indispensable because no isolated image identifies the pathogen or its antibiotic susceptibility.

The differential diagnosis of obstruction is built by integrating chronology and anatomy. A high gradient from baseline with mobile leaflets and a reduced indexed area suggests prosthesis-patient mismatch, whereas a rapid increase in the setting of inadequate anticoagulation points toward prosthetic valve thrombosis; slow progression associated with calcification and leaflet abnormality is more consistent with structural degeneration, whereas dense subannular tissue favors pannus.

For regurgitation, the differential diagnosis separates physiological jets from intraprosthetic regurgitation and paravalvular leak. Late dehiscence associated with fever or abscess should be considered infectious until proven otherwise, whereas important regurgitation immediately after TAVI may result from calcification, malapposition or underexpansion. For correction planning, a three-dimensional map of the defect is often more useful than the severity label alone.

Pathway in acute and progressive dysfunction

In an unstable patient, diagnosis and stabilization must proceed simultaneously. Oxygenation, circulatory support, arrhythmia control and treatment of pulmonary edema are necessary but must not delay identification of critical obstruction or acute regurgitation; bedside TTE immediately assesses gradients and ventricular function, while transesophageal echocardiography, fluoroscopy or CT are selected according to availability and tolerability. The cardiac surgeon and interventional cardiologist should be involved before organ damage makes definitive treatment prohibitive.

An obstructed mechanical prosthesis with hemodynamic compromise is an emergency, and the choice between surgery and fibrinolysis depends on valve position, thrombus size, embolic and bleeding risk, surgical availability and the likelihood of pannus. The decision cannot be based solely on a low INR because, when pannus is the obstructing tissue, fibrinolysis cannot remove it and risks only delaying definitive treatment.

Severe acute regurgitation caused by bioprosthetic rupture, dehiscence or endocarditis may be poorly tolerated and require rapid therapeutic escalation. Vasodilation and diuretics can serve as a bridge in appropriate patients but do not repair the defect; infection with abscess, instability, embolization or severe regurgitation requires urgent surgical assessment. The presence of a prosthesis increases microbiological and anatomical complexity and supports management by an Endocarditis Team.

In a stable patient, the first priority is instead to verify that the abnormality is reproducible by documenting or correcting blood pressure, heart rate, hemoglobin, rhythm and stroke volume and repeating measurements with a comparable technique. A modest isolated change may reflect different conditions, whereas a concordant trajectory of gradient, DVI, area and morphology supports true deterioration.

Clinically significant bioprosthetic valve thrombosis may regress with anticoagulation, and subsequent imaging should document recovery of leaflet mobility and gradients. Calcification and tearing, by contrast, are not pharmacologically reversible; recognizing the difference avoids the two opposite errors of reintervening on treatable thrombosis or prolonging ineffective anticoagulation in advanced degeneration.

When dysfunction is mild and asymptomatic, follow-up is intensified and the patient receives precise instructions about symptoms to report. This is not passive waiting: progression, ventricular response, pulmonary pressure and functional capacity are measured because dyspnea attributed to age, voluntary reduction in activity or frailty can mask a clinically important lesion. Selected exercise testing can objectify the limitation.

The report should conclude with a graded mechanistic description, indicating the probability of obstruction, location and severity of regurgitation, consequences and the next recommended examination. Generic formulations such as “questionable prosthesis”, without measurements or baseline comparison, do not guide care; when findings are discordant, it is preferable to review the images in an experienced center before classifying the valve as failed.

Treatment, reintervention and follow-up after diagnosis

Treatment should target the cause: optimized anticoagulation is central in selected thrombosis, antibiotics and surgical source control in endocarditis, while surgery or transcatheter procedures are reserved for irreversible mechanical lesions. Diuretics, rate control and heart-failure therapy may reduce congestion and risk, but they do not turn a severely obstructed or regurgitant prosthesis into a normal valve.

Redo surgery allows removal of the prosthesis, pannus and infected tissue, annular reconstruction, leak correction and simultaneous treatment of coronary disease, aortic disease or other valves. Risk increases with urgency, previous operations, radiation exposure, frailty and organ damage, but it cannot be reduced to a simple sum of scores because technical feasibility and center experience can substantially modify the outcome.

Valve-in-valve can treat a degenerated bioprosthesis in selected patients, but not a mechanical prosthesis. Because the old ring remains in place, the new device may leave a residual gradient, and CT must assess coronary anatomy, internal diameter and access; in the mitral position the neo-LVOT must also be estimated. Age, the risk of a third intervention and future coronary access are part of the same decision because solving the current problem should not compromise the lifetime strategy.

For paravalvular leaks, percutaneous closure and surgical reintervention have different indications. Focal defects, favorable anatomy and high surgical risk may be treated with devices, whereas active endocarditis, extensive dehiscence or the need for other corrections favor surgery; an apparently small residual defect may nevertheless maintain hemolysis if the jet remains highly accelerated. Success therefore cannot be defined by visual reduction in area alone.

The Heart Team decision integrates certainty of mechanism, severity, symptoms, ventricular response, comorbidities, anatomy, risk and patient preferences. Age alone does not automatically assign surgery or catheter treatment: in younger patients, durability and the feasibility of future procedures carry greater weight, whereas in frail patients expected recovery, quality of life and the likelihood that prosthetic valve dysfunction truly explains the symptoms become central.

After any treatment, a new echocardiographic reference should be established, documenting gradient, regurgitation, ventricular function and hemodynamic conditions. After anticoagulation the examination verifies prosthetic valve response, whereas after an intervention it records the result and any residual abnormalities; criteria for strategy failure should also be established in advance to avoid months of ineffective treatment while heart failure or hemolysis progresses.

Prevention includes correct anticoagulation for mechanical prostheses, appropriate antithrombotic therapy for bioprostheses, oral hygiene, prophylaxis for indicated procedures and rapid access to care in the event of fever. The patient should also keep a document recording the model, size, implantation date and INR target because independently stopping the VKA, ignoring a fever or waiting until dyspnea becomes severe are all modifiable causes of late presentation.

Prognosis depends less on the generic name of the complication than on how quickly its cause and consequences are recognized. Thrombosis treated before shock may be reversible; a leak corrected before heart failure and chronic hemolysis may allow recovery; planned management of degeneration permits a broader choice than emergency treatment. Serial follow-up therefore transforms the prosthesis from an object to be checked into a physiological system to be understood.

A specialist program also preserves non-echocardiographic data that become decisive over time: the operative report, manufacturer, size, suture type, any annular enlargement, TAVI implantation depth and preprocedural CT images. When a complication develops, this information reconstructs what echocardiography cannot show, distinguishes an original anatomical limitation from an acquired change and allows a new intervention to be simulated without repeating unnecessary investigations. The quality of documentary continuity is therefore a concrete component of clinical quality.