Reentry ventricular tachycardia with anatomical obstacle is a form of sustained monomorphic ventricular tachycardia caused by the presence of a reentry circuit established around a fixed anatomical obstacle, such as a post-infarction scar or myocardial fibrosis. Unlike other forms of ventricular tachycardia, reentry in this type of arrhythmia is based on a permanent structural substrate, which leads to recurrent activation of the ventricular myocardium.
This arrhythmia occurs mainly in patients with advanced structural heart disease, particularly following myocardial infarction or in dilated cardiomyopathy. The ventricular electrical instability associated with these substrates promotes the development of stable reentry circuits, which can generate episodes of sustained ventricular tachycardia.
Reentry VT with anatomical obstacle is of particular clinical relevance as it can cause hemodynamically unstable episodes and increase the risk of sudden cardiac death. Early recognition of the arrhythmic substrate is essential to establish an appropriate therapeutic strategy, which may include catheter ablation or implantation of an implantable cardioverter-defibrillator (ICD).
The main mechanism of reentry VT with anatomical obstacle is the presence of a structural barrier within the myocardium, which prevents the uniform propagation of electrical impulses, creating an abnormal electrical circuit. This condition results from pathological processes that damage the myocardial tissue and lead to the formation of fibrotic tissue with altered electrophysiological properties.
The main causes leading to the formation of these reentry circuits are:
Reentry VT with anatomical obstacle develops in the presence of a stable structural substrate that alters the normal flow of the electrical impulse.
The formation of a reentry circuit depends on three fundamental elements:
When an electrical impulse encounters an area of unidirectional block, it may enter a slow conduction pathway and subsequently re-enter the circuit via the rapid pathway. This process repeats cyclically, generating sustained ventricular tachycardia.
From the electrocardiographic point of view, reentry VT with anatomical obstacle presents with a wide QRS, with a morphology that is typical for each patient, depending on the location of the scar and the path of the reentry circuit. In patients with anterior myocardial infarction, VT often shows a left bundle branch block with inferior axis, while in those with inferior infarction, the morphology may be that of a right bundle branch block.
Clinically, reentry VT with anatomical obstacle is characterized by a highly stable rhythm, with episodes that can self-sustain for several minutes or hours, increasing the risk of hemodynamic compromise.
The hemodynamic repercussions of reentry VT depend on the tachycardia rate and the patient’s cardiac function. In patients with pre-existing ventricular dysfunction, prolonged episodes of tachycardia may cause:
In some patients, repeated episodes of VT may lead to the development of tachycardiomyopathy, a form of heart failure that is reversible once the tachycardia is interrupted and sinus rhythm restored.
Reentry ventricular tachycardia with anatomical obstacle develops exclusively in patients with a pathological structural substrate, such as a post-infarction scar or myocardial fibrosis. However, the onset of these changes is not random: there are risk factors that promote the formation of fibrotic or scar tissue and thus increase the likelihood of developing this arrhythmia.
The main risk factors include conditions that promote chronic myocardial injury and progression of ventricular fibrosis:
Prevention of reentry VT with anatomical obstacle is based on careful management of cardiovascular risk factors and protection of residual myocardial tissue in patients with structural heart disease. Controlling hypertension with ACE inhibitors or sartans, managing diabetes and dyslipidemia with hypoglycemic agents and statins, and lifestyle modification with smoking cessation and regular physical activity are essential strategies to slow disease progression and reduce arrhythmic risk.
In patients with known heart disease, careful cardiac monitoring is essential, with tests such as cardiac magnetic resonance imaging to identify potentially arrhythmogenic areas of fibrosis early. In some cases, electrophysiological evaluation may identify latent reentry circuits, allowing for early intervention with catheter ablation. In high-risk patients for sudden death, implantation of an ICD represents the main strategy for secondary prevention.
The clinical presentation of reentry VT with anatomical obstacle is closely related to the underlying pathology.
A history of myocardial infarction is the most significant finding, as it suggests the presence of an arrhythmogenic scar substrate.
Patients with dilated cardiomyopathy or history of cardiac surgery should also be considered at risk. It is essential to collect information regarding the presence of rapid and regular palpitations, episodes of presyncope or syncope, and previous signs of heart failure.
In patients with residual ischemia or electrolyte imbalances, VT may appear suddenly. Some patients report episodes of self-limiting ventricular tachycardia, while in others, tachycardia may persist, leading to hemodynamic instability.
The symptomatology of reentry VT with anatomical obstacle depends on the rate of tachycardia and the patient’s hemodynamic reserve.
Palpitations are often the first symptom reported, described as sudden, rapid, and regular.
In patients with reduced ventricular function, tachycardia may lead to progressive exercise intolerance and worsening dyspnea during arrhythmic episodes.
In more severe cases, reduced cerebral blood flow leads to presyncope or syncope. Some patients report chest pain, especially if concomitant myocardial ischemia is present.
During an episode of sustained VT, the patient may present with signs of hemodynamic instability; the heart rate is generally between 120 and 200 bpm, with a regular but often weak pulse.
In more advanced cases, reduced cardiac output may cause hypotension, accompanied by sweating, pallor, and, in patients with left ventricular dysfunction, signs of pulmonary congestion such as basal rales.
In subjects with advanced cardiomyopathy, prolonged episodes of tachycardia may lead to worsening heart failure, with the appearance of dependent edema and increased jugular venous pressure.
Reentry ventricular tachycardia with anatomical obstacle must be rapidly recognized to establish appropriate treatment and prevent serious complications.
The clinical suspicion arises in patients with known structural heart disease, such as post-myocardial infarction, dilated cardiomyopathy, myocardial fibrosis, who experience episodes of sustained tachycardia with regular rhythm and wide QRS, with symptoms ranging from sudden palpitations and dyspnea to syncope in the most severe cases, when hemodynamic compromise is significant.
Anamnesis should investigate the frequency and duration of episodes, presence of triggers, and response to previous pharmacological treatments. A positive history for myocardial ischemia, cardiac surgery, or heart failure increases the likelihood that the arrhythmia is of ventricular origin.
The 12-lead ECG is the first diagnostic tool to identify ventricular tachycardia and distinguish it from other wide QRS arrhythmias. The main features of reentry VT with anatomical obstacle include:
Recognition of QRS morphology is essential to localize the origin of the arrhythmia and guide further diagnostic assessment.
If the arrhythmic episode is not documented on a standard ECG, prolonged monitoring is used to record intermittent episodes and correlate symptoms with the presence of tachycardia. The most used tools are:
Reentry VT with anatomical obstacle must be differentiated from supraventricular tachycardias with aberrancy, which may present with a similar electrocardiographic appearance. Some pharmacological tests and specific maneuvers are used for this purpose:
In patients with known or suspected structural heart disease, imaging is essential to identify the arrhythmogenic substrate. The most useful investigations include:
These tests allow precise identification of damaged tissue areas that may serve as a substrate for reentry of the electrical impulse.
In cases where the diagnosis remains uncertain or an ablative intervention is planned, an electrophysiological study (EPS) is indicated. This invasive procedure allows to:
In some patients, EPS is also useful for evaluating the need for implantation of an ICD, especially in those with significant ventricular dysfunction or recurrent sustained VT.
A methodical diagnostic approach, based on clinical and instrumental analysis, allows precise identification of the arrhythmia, exclusion of alternative diagnoses, and setting of a targeted treatment plan, avoiding unnecessary interventions and improving patient prognosis.
The treatment of reentry ventricular tachycardia with anatomical obstacle depends on the patient's hemodynamic stability and the frequency and duration of episodes. Management is based on a sequential approach that includes termination of the acute arrhythmia, prevention of recurrences, and, in selected cases, definitive treatment with ablation or ICD.
In patients with sustained VT, the priority is restoration of sinus rhythm. The choice of acute therapy depends on the patient's hemodynamic status:
If tachycardia does not respond to pharmacological therapy, electrical cardioversion is necessary.
Once the acute episode is terminated, it is essential to establish a strategy to reduce the risk of recurrence. Chronic therapy depends on the frequency of episodes, presence of structural heart disease, and risk of sudden death.
The therapeutic options include:
In patients with ischemic heart disease, revascularization may reduce the arrhythmic burden and improve prognosis.
Treatment must be tailored to patient characteristics. In those with a single self-limiting episode, careful monitoring without specific therapy may be sufficient. In patients with recurrent VT, a combination of drugs and ablation may be the best strategy. In cases with a high risk of sudden death, the defibrillator is the only effective option.
The prognosis of reentry VT with anatomical obstacle depends on the underlying pathology, ventricular function, and presence of effective therapies. In patients with advanced ventricular dysfunction, the risk of sudden death is significant, especially in the absence of adequate treatment.
Catheter ablation is an effective therapeutic option, with a success rate exceeding 80% in patients with well-defined circuits. However, in patients with extensive myocardial scars, VT may recur despite ablation, requiring combined use of antiarrhythmic drugs and ICD.
In patients with an ICD, long-term prognosis is improved, as the device can promptly treat episodes of ventricular tachycardia or fibrillation. However, quality of life may be impaired in subjects receiving frequent shocks.
Without treatment, reentry VT with anatomical obstacle may progress to more unstable forms, with a progressive risk of heart failure and arrhythmic death. For this reason, early diagnosis and targeted treatment are essential to improve survival and quality of life.