L. R. Erhardt

Single right-sided precordial lead in the diagnosis of right ventricular involvement in inferior myocardial infarction*

The ST segment in a single right-sided chest lead, CR4R, has been studied in 92 consecutive patients with acute inferior transmural left ventricular myocardial infarction. A transient ST- segment rise of more than 1 mm. was recorded in 35 patients, and strongly indicated a significant extension of the infarction to the posterior free right ventricular wall according to autopsy findings. This ECG pattern was furthermore associated with right-sided heart failure, hypotension and oliguria. Left heart failure was also common. The short-term prognosis of patients with ST-segment elevation in CR4R was poor.

Continuous vectorcardiography in acute myocardial infarction. Natural course of ST and QRS vectors

We made continuous recordings of the X, Y and Z Frank leads in 43 patients with their first myocardial infarction admitted within 4 hours of the onset of pain. Sequential hourly analysis of the ST and QRS vector changes during the first 24 hours was performed. In short-term survivors (n = 38) mean serial changes of ST vectors showed an initial rapid decline until the 8th-10th hour, whereas QRS vector changes lasted longer and were completed within 13.5 +/- 3.6 hours (inferior infarction) and 10.2 +/- 2.4 hours (anterior infarction) respectively. The initial ST vector magnitude was significantly correlated to the subsequent cumulative QRS vector change (r = 0.82). The individual ST vector changes showed a rapid decline in 33 of 38 patients (87%), whereas in 5 patients the ST vector magnitude increased to reach its maximum after 4-6 hours. After the initial decline new increases of the ST vector magnitude was noted in 16 patients on 20 occasions. In 13 instances this was associated with recurrent pain. The spatial change of ST vector direction with reference to the initial direction was significantly greater when recurrent ST rises were accompanied by additional QRS vector changes, compared to those without associated QRS changes (P less than 0.025). The individual QRS vector slopes could be characterized as (1) monophasic (n = 21, 55%), (2) polyphasic (n = 11, 29%) and (3) irregular (n = 6, 16%). We conclude that continuous vectorcardiography is a suitable method for following ST and QRS vector changes that accompany acute myocardial infarction and that ST vector changes can be used to predict subsequent QRS vector changes.

Abnormal atrial activity in lipomatous hypertrophy of the interatrial septum

Summary Five cases of lipomatous hypertrophy of the interatrial septum were found in a prospective study of 445 necropsies. All five patients had abnormal atrial activity. Two patients had atrial fibrillation, one patient had a wandering atrial pacemaker, and two patients had a pathological P vector with negative P waves in Leads II, III, and aV F . The changes seen in the latter three cases might be caused by interatrial conduction disturbances, shift of pacemaker site, or both.

Beta receptor antagonists in the treatment of heart failure

SummaryThe use of beta-receptor antagonists in the treatment of heart failure is controversial. Available data do not allow general recommendations regarding their use. In dilated cardiomyopathy, several studies suggest that long-term treatment in individual patients reduces symptoms and increases exercise capacity. Short-term treatment is usually not beneficial, except in patients with ischemically induced left ventricular dysfunction. In heart failure, post myocardial infarction and in chronic ischemic heart disease, no proper long-term study has been performed to evaluate its effects. However, patients with acute myocardial infarction tolerate beta blockers, despite the presence of left ventricular dysfunction and long-term prognosis is improved. Newer agents, some with ancillary properties, such as intrinsic activity and vasodilatation, may have advantages. In the future we need a better description of the cardiac status in our patients in order to be able to select those that will respond favorably to beta-receptor antagonists. The mechanisms by which some patients improve are still obscure. Protection against receptor downregulation, restoration of receptor density, protection against cardiotoxicity of catecholamines, and improvement in ischemic systolic and diastolic left ventricular function are all possible. The fear that beta-receptor antagonists are dangerous in heart failure is in most instances not warranted, but an initial deterioration may have to be accepted in order to gain long-term beneficial effects. Ongoing studies in both idiopathic cardiomyopathy and in postinfarction failure will hopefully help us to define the use of beta-adrenoreceptor antagonists in the future.