Right Ventricular Infarction: A Clinical study

INTRODUCTION : Myocardial infraction is the term used when the myocardium is necrosed due to ischemia. It may be transmural or subendocardial. Inferior wall infarction has got some special features like association with right ventricular infarction and brady arrhythmias especially sinus bradycardia and second degree AV Block. Right ventricular infarction is different from that of the left ventricle in the acute presentation, therapy and long term prognosis. The early recognition of Right ventricular myocardial infarction is important, because the time of onset of its hemodynamic consequence is unpredictable and these may be prevented by the administration of intravenous fluid load. The description of Right ventricular myocardial infarction appeared more than 60 years ago. But it was considered unimportant until Cohn and co-workers in 1974 published their classic report on Right ventricular myocardial infarction as a distinct clinical entity. The reported incidence is between 25-50% of Inferior Wall Myocardial Infarction. Involvement of RV s related to severe altherosclerotic occlusion of the right coronary artery and is associated with involvement of postero-inferior wall and posterior of the septum. Clinically Right ventricular myocardial infarction can be suspected when a patient with Inferior Wall Myocardial Infarction presents with elevated JVP, positive kussmaul’s sign, hypotension, right sided third or fourth hear sounds, tender hepatomegaly, oliguria, rarely TR and clear chest. Electrocardiogram was generally believed to be unhelpful in identifying Right ventricular myocardial infarction, until Erhardt and co-workers described the value of a right precordial lead in patient with autopsy proven Right ventricular myocardial infarction. A 1 mm ST elevation in this lead is 70% sensitive and 100% specific. The change is transient. In one series, 48% of the patients had resolution of ECG changes with in 10 hours of the onset of symptoms. Since bradycardia is the most common arrhythmia occurring during early phases of Acute Myocardial Infarction and is particularly frequent in patients with inferior and posterior infarction. All types of AV conduction disturbances and intraventricular blocks can occurs more commonly in Inferior Wall Myocardial Infarction than AWMI. Of these, 2nd mobitz type – 1 AV block occurs commonly in Inferior Wall Myocardial Infarction than Anterior Wall Myocardial Infarction. This is usually transient and does not persist for more than 72 hours after infarction. AIM OF THE STUDY To study the clinical profile of Right ventricular myocardial infarction and, 1. To find the incidence of Right ventricular myocardial infarction in patients having inferior wall myocardial infarction. 2. To analyse age and sex distribution. 3. To analyse the symptamatology and risk factors. 4. To analyse the clinical features. 5. To analyse the complication and outcome following Right ventricular myocardial infarction. 6. To analyse the mortality following right ventricular myocardial infarction. MATERIALS AND METHODS : This study was conducted during 2006-2007 period. 50 consecutive patients admitted to the coronary care unit or general medical wards with a diagnosis of acute inferior wall infarction were included in the study. Inclusion Criteria: Patients having inferior wall myocardial infarction. All patients included in the study were subjected to ECG examination of V3R and V4R in addition to the conventional 12 leads. Rhythm strip were taken in patients with arrhythmias. ECGs were examined at the time admission, second day and up to the day of discharge. Only those cases with hyperacute inferior wall infarction were included in the study. Patients with slope elevation of ST segment in leads, II, III and a VF were taken as having hyperacute inferior wall infarction. Right ventricular infarction was diagnosed if there was ST elevation equal to or more than 1 mm in V4R. All patients were assessed clinically and electrocardiographically with special emphasis on presenting complaints, risk factors, vital signs, arrhythmias and mortality. Patients were followed up till discharge. Exclusion Criteria: Patients having history of, 1. Chronic Lung disease 2. Previous MI 3. Rheumatic Heart disease 4. Pericardial disease or LBBB Because diagnosis of right ventricular infarction is not possible in these cases when ECG is used as the criteria. Patients who presented after 24 hrs of onset of chest pain were excluded as the ST changes in right ventricular infarction may be transient. CONCLUSION : 1. The incidence of Right ventricular infarction in this study is about 40%, which is almost equal to that of previous studies. 2. The incidence of Right ventricular myocardial infarction is much higher in males than in females. 3. In males there is a distinct increase in the incidence after the age of 40 years in this study. 4. Almost all patients had typical retrosternal chest pain lasting more than 30 minutes associated with sweating. Syncope was a prominent symptom in patients with right ventricular infarction. 5. Smoking was the most prevalent risk factor. 6. The incidence of True Posterior wall MI in this study was 16%. 7. Hypotension and Bradycardia is a commonest clinical feature associated with Right ventricular myocardial infarction. 8. There should be a strong suspicion of Right ventricular myocardial infarction (98%) in all cases of inferior wall myocardial infarction presenting with features of cardiogenic shock and hypotension. 9. All cases of Inferior wall infarction should have right sided chest leads recorded during ECG examination and this should be done as early as possible. If diagnosis of Right ventricular infarction is correctly made and treated the prognosis is usually good. 10. Mortality is higher in patients with Right ventricular infarction when compared with those without this complication. This was due to higher incidence of conduction disturbances and pump failure. In this study mortality is around 14%.