Isolated right ventricular infarction with ventricular tachycardia

Isolated right ventricular myocardial infarction caused by occlusion of an anomalous non-dominant right coronary artery: successful management with percutaneous coronary intervention

Isolated right ventricular myocardial infarction (RVMI) is a rare clinical presentation of acute coronary syndrome. A high index of suspicion is needed for its timely diagnosis and management to prevent serious complications like heart failure, cardiogenic shock, ventricular arrythmias or sudden cardiac death. Coronary anomalies are rare entities with a varied clinical presentation. We report an interesting case of a middle-aged female who presented with isolated RVMI, with a borderline blood pressure and sinus node dysfunction resulting from occlusion of an anomalous right coronary artery. The successful management of this patient with percutaneous coronary intervention using coronary stenting is also discussed.

Symptomatic right ventricular ischemia secondary to a critical stenosis in a nondominant right coronary artery

Stable angina pectoris owing to isolated right ventricular ischemia from a critical stenosis in a nondominant right coronary artery is a rare entity and documentation of isolated right ventricular ischemia even rarer. We present a case of isolated right ventricular ischemia documented by fractional flow reserve (FFR) and resolution of symptoms after percutaneous coronary intervention.

Coronary dominance and prognosis of patients with acute coronary syndrome

BACKGROUND

A number of studies have identified the number of diseased vessels to be an important determinant of survival in patients with acute coronary syndrome (ACS). It is unknown if coronary dominance has an impact on prognosis of these patients. We hypothesized that the prognosis of patients with ACS with left dominance (LD) would be worse than that of patients with right or mixed dominance.

METHODS

The study population consisted of 27,289 patients whose primary indication for cardiac catheterization was ACS. The patients were divided into 3 groups according to coronary dominance. The mean duration of follow-up was 3.5 years (range 1-6.5 years). A Cox proportional hazards analysis was used to compare survival by dominance, adjusting for age, sex, diagnosis, comorbidities, severity of coronary disease, and ejection fraction.

RESULTS

The rates and patterns of revascularization among patients with significant coronary disease were similar between the groups. At the end of follow-up, patients with LD had a significantly higher mortality (hazard ratio 1.18, 95% CI 1.05-1.34; adjusted hazard ratio 1.13, CI 1.00-1.28). The mortality of patients with mixed and right dominance was similar.

CONCLUSION

In patients with ACS, LD is a significant and independent predictor of increased long-term mortality. Further research is needed to determine mechanisms of increased mortality in patients with LD and measures that can be taken to improve the outcome of patients with left-dominant circulation.

Ventricular fibrillation resulting from acute right ventricular infarction from isolated occlusion of a right ventricular branch artery

Malignant ventricular arrhythmias can result from isolated right ventricular infarction, and reports of this phenomenon in the literature are rare. We present a case of a 46-year-old man with acute onset of chest pain angiographically confirmed to be a result of isolated occlusion of a right ventricular branch artery. He developed ventricular fibrillation within 5 hours of symptom onset. This case highlights the point that despite its benign clinical appearance and preserved left ventricular function, necrosis of right ventricular tissue can have life-threatening consequences.

Nondominant right coronary artery occlusion and ventricular tachyarrythmias

It is usually considered that occlusion of a nondominant right coronary artery is not associated with significant consequences. We report two cases of nondominant right coronary artery occlusion that presented with sudden cardiac death. Timely intervention resulted in complete resolution of the ventricular arrhythmias. This highlights the need for greater vigilance in the recognition and treatment of these lesions.

Primary angioplasty for isolated right ventricular infarction

We describe a case of isolated right ventricular infarction that has rarely been diagnosed antemortem. Electrocardiogram showed ST segment elevation in left precordial chest, right precordial chest, and inferior leads, which mimicked those of anterior and inferior left ventricular infarction. Coronary angiography revealed that culprit lesion was totally occluded right coronary artery. Infarcted artery was nondominant right coronary artery with branches supplying only right ventricular wall. Restoration of coronary blood flow was obtained by primary stenting and resulted in prompt ST segment normalization in all leads. Despite extensive right ventricular wall motion abnormality, subsequent right ventricular dysfunction was not observed.

Perfusion of myocardial segments of the right ventricle: role of the left coronary artery in infarction of the right ventricle

In a series of 88 human hearts, from individuals aged between 24 h and 94 yr (x= 61.09 +/- 21.96), the coronary arterial distribution of the right ventricle was studied using a modified Selvester's system of segmentation. Postmortem angiographies and microdissection techniques were used. The analysis of the six segments of the right ventricle shows that the three anterior segments, basal, mesial, and--less frequently--apical, present a type of irrigation that is practically constant and is dual. The postero-basal and postero-mesial segments are irrigated almost exclusively by the right coronary artery. In the remaining segments the vascularization was of mixed type, although a considerable degree of exclusive arterial perfusion was observed in the antero-apical segment. The segmental analysis allows us to conclude that although arterial vascularization of the right ventricle depends fundamentally on the right coronary artery, the anterior interventricular artery irrigates more than 20% of the right ventricular myocardium. Results from segmental analysis are compared with data from clinical and necropsic studies.

Right ventricular infarction causes heterogeneous autonomic denervation of the viable peri-infarct area

BACKGROUND

Because efferent autonomic pathways to the right ventricle (RV) differ from the efferent autonomic projections to the left ventricle (LV), we assessed the effects of RV infarction on this innervation.

METHODS AND RESULTS

We measured the ventricular effective refractory period (ERP) shortening in response to bilateral ansae subclaviae stimulation and ERP lengthening induced by bilateral vagal stimulation as markers of autonomic innervation before and after RV myocardial infarction (RVMI) produced by coronary ligation (n=28 dogs) or intracoronary latex injection (n=18 dogs) into a marginal branch of the right coronary artery in open-chest anesthetized dogs. In each dog, ERPs measured in viable peri-infarct area at two RV outflow tract (RVOT) sites and two septal and four lateral sites at the RV free wall after RVMI showed reduced or absent ERP shortening during bilateral ansae subclaviae stimulation laterally, septally, and at RVOT sites 3 hours after RVMI. ERP shortening in response to infused norepinephrine was still present. Bilateral vagal stimulation during background norepinephrine infusion (0.10 to 0.25 microg/kg per minute) lengthened the ERP at all test sites before latex injection. After transmural RVMI, vagally induced ERP prolongation was attenuated or lost at lateral, septal, and RVOT test sites.

CONCLUSIONS

RVMI causes sympathetic and vagal denervation at viable sites at the RVOT, lateral, and, to a lesser extent, septal sides of the viable peri-infarct area. Autonomic denervation in the RVOT might contribute to the development of ventricular tachyarrhythmias after the acute stage of myocardial infarction involving the RV.

A new experimental model of isolated myocardial ischemic injury: ECG findings of acute isolated right ventricular ischemic injury

A new experimental porcine model for creating selective ischemia of a specific part of the myocardium while the rest of the myocardium remains free of ischemia has been used to study the electrocardiographic (ECG) changes deriving from selective ischemia of the right ventricular (RV) free wall. A patch was stitched to the ventricle to produce selective myocardial ischemic injury. In a preliminary study of nine pigs, selective ischemia of the left ventricular free wall in five and of the RV free wall in four animals was induced, and a postmortem dye injection was performed to evaluate blood flow in the area of ischemia. In an ECG study of 20 pigs, the baseline ECG was recorded with use of the standard leads I-III, aVR, aVL, and aVF, left precordial leads (V1-V6), and leads V4R, V3H, and V4H and 1 hour after inducing ischemia, the ECG study was repeated. Our experimental model produced ischemic injury in which the location and surface area were known antemortem. In the 20 pigs, ST-segment changes were recorded in leads V1-V3, V3H, and V4H. In only four pigs (20%) was ST-segment elevation recorded in lead V4R. The results show that the ECG signs of selective ischemia of the RV free wall may imitate the signs of anterior or anterolateral infarction of the left ventricle. In this study, elevation of the ST-segment in lead V4R was not pathognomonic of for RV ischemia. This model is a new tool for studying hemodynamic and ECG changes of selective univentricular or biventricular ischemic injury.

Importance of a non-dominant right coronary artery occlusion presenting as sudden cardiac death with prolonged right ventricular dysfunction and malignant arrhythmias

We report a case of a patient who presented with sudden cardiac death secondary to a subtotal occlusion of a small non-dominant right coronary system. Catheterization several weeks following the initial episode revealed persistent severe right ventricular dysfunction with moderate hemodynamic compensation. Continued unstable arrhythmogenic potential at this point led to placement of an AICD device. The case highlights the potential hazard and often complacency involved in dealing with benign appearing lesions as this one.

Isolated right ventricular infarction

Our experience with 18 cases of isolated right ventricular infarction is reported and the literature is reviewed. Chronic lung disease with right ventricular hypertrophy is an important risk factor. Chest pain is the usual symptom at presentation but some cases can have breathlessness, palpitations or syncope. Some cases can have sinus bradycardia, atrial fibrillation or ventricular tachycardia. Atrioventricular block is rare. Cases with pulmonary artery hypertension, extensive right ventricular infarction due to proximal occlusion of the right coronary artery, right atrial infarction or atrial fibrillation can have hypotension and/or systemic venous congestion. A surface electrocardiogram mainly showing changes in leads conventionally considered to represent left ventricle and right-sided chest leads may not show an infarct pattern in some cases. Echocardiography is, therefore, more reliable in diagnosing this condition. The cautious use of small doses of nitrates and diuretics is not hazardous in the absence of hypotension. High doses of steroids and anti-coagulants can be helpful. The prognosis is usually good, although sudden collapse can occur due to ventricular fibrillation, rupture of the right ventricular free wall or a massive pulmonary embolism.

Isolated right ventricular infarction

The literature on isolated right ventricular infarction is reviewed and local experience is reported. Chronic lung disease is an important risk factor. Chest pain and breathlessness are common. Syncope and sudden collapse can also occur. Rhythm disorders include sinus bradycardia, atrial fibrillation and ventricular tachycardia or fibrillation. Atrioventricular block is rare. Hypotension and a right-sided fourth heart sound are common. Cautious use of slow-release nitroglycerin is not hazardous in the absence of hypotension. High doses of steroids and anticoagulants can be helpful. The prognosis is usually good, although sudden collapse can occur due to ventricular fibrillation, rupture of the right ventricular free wall or massive pulmonary embolism.

Isolated right ventricular infarction mimicking additional infero-posterior left ventricular infarction

A case of isolated right ventricular infarction mimicking additional infero-posterior left ventricular infarction on the surface electrocardiogram is presented. Gross dilatation of the right ventricle was probably responsible for the electrocardiographic findings.

Ventricular tachycardia originating from the right ventricular free wall in a patient with an old myocardial infarction

A 64-year-old woman with right ventricular infarction had ventricular tachycardia (VT) with left bundle-branch block morphology. Pace-mapping during sinus rhythm and the earliest ventricular potential during VT suggested that the VT originated in the inflow-inferior site of the right ventricular free wall.

Concomittant ST elevation in inferior and anterior leads in acute myocardial infarction. Clinical and anatomical significance

Various instances of acute myocardial infarction that may cause concomittant ST-segment elevation in inferior and anterior leads are presented. Among the situations that produce this phenomenon are: (1) multivessel coronary artery disease or isolated disease of a dominant left anterior descending artery causing combined inferior and anterior myocardial infarction; and (2) isolated disease of a right coronary artery causing combined infarction, or isolated right ventricular myocardial infarction. The mechanisms responsible for the electrocardiographic patterns in each instance are discussed.

Electrocardiographic manifestations of right ventricular infarction

RVI is a frequent occurrence in the setting of an acute inferoposterior myocardial infarction and its early recognition has important therapeutic and prognostic implications. Because of this, diverse invasive and noninvasive diagnostic techniques have been investigated to identify patients with RVI. Electrocardiography is the most available, simple, and objective of these techniques. Numerous ECG signs of RVI have been described and some of them, especially ST segment elevation and patterns of necrosis (QS, QR) in the right precordial leads (V3R to V5R), have a very high sensitivity, specificity, and positive predictive value for the detection of RVI. ST segment elevation in lead V4R is also helpful in identifying the occluded coronary artery in patients with acute myocardial infarction, which could have great importance in their management. Hence, a 12-lead ECG with the right precordial leads (V3R to V6R) should be a routine part of the initial evaluation of patients with clinical suspicion of acute inferior myocardial infarction. This article reviews the value, limitations, and pathogenesis of the ECG manifestations of RVI.

Nondominant right coronary artery occlusion presenting with isolated right ventricular infarction and ventricular fibrillation

It is generally believed that serious complications are unlikely in a myocardial infarction resulting from occlusion of a nondominant right coronary artery. A case of isolated right ventricular infarction caused by total occlusion of a nondominant right coronary artery complicated by two episodes of ventricular fibrillation is presented.