Comparison of newer antiarrhythmic agents

In the past decade a number of new antiarrhythmic drugs have been introduced. They have been extensively used in the acute phase of myocardial infarction. Few, if any, long-term comparative trials of these newer agents have been reported. Most of these newer agents have been shown to be able to reduce the frequency of ventricular arrhythmias but not the mortality rate. Beta blockers and some antiplatelet adhesive drugs, however, have reduced the mortality rate following myocardial infarction. There is a need for long-term properly stratified trials of these effective agents.     

Hemodynamic and antiarrhythmic effects of tocainide in patients with acute myocardial infarction

In order to evaluate the hemodynamic and antiarrhythmic efficacy of tocainide, studies were performed in patients suffering acute myocardial infarction. Intravenous tocainide was administered over a 15-minute period in order to determine its acute effects and subsequently, in a randomized double-blind study with placebo control, to determine its effects over a 24-hour period in acute myocardial infarction. Tocainide resulted in a significant decrease of frequent and complex ventricular arrhythmias acutely and had only minimal effects of hemodynamics in most patients. In the long-term studies, tocainide produced no adverse hemodynamic effects when compared with placebos.     

Metabolism of apolipoprotein A-I in healthy young adults.

The metabolism of 125I-labeled apolipoprotein A-I bound to high-density lipoproteins by an in vitro transfer procedure was studied in 10 healthy young adults (5 males and 5 females). Both sexes handled the labeled apolipoprotein similarly, and no statistically significant differences were found in the derived kinetic data. The mean (+/- 1 SD) plasma apolipoprotein A-I concentrations (males, 105 +/- 19 mg/dl; females, 111 +/- 13.8 mg/dl) and half-lives (males, 4.46 +/- 0.45 days; females, 4.64 +/- 0.70 days) were similar, as were the fractional rates of catabolism (FCR) of the apoprotein derived from the above data (FCR in males, 27% of intravascular pool/day; FCR in females, 25% of intravascular pool/day). The absolute catabolic rate of the apoprotein, equivalent under steady-state conditions to the synthetic rate, was 12.1 +/- 1.6 mg/kg/day in males and 11.9 +/- 2.4 mg/kg/day in females.     

High density and low density lipoprotein subfractions in survivors of myocardial infarction and in control subjects

The major lipoprotein classes (very low, low and high density lipoproteins, VLDL, LDL and HDL) and three lipoprotein subfractions (HDL₂, HDL₃ and LDL₂) of 31 male survivors of myocardial infarction (MI) have been compared with those of 24 ostensibly normal subjects. The two groups had similar ages, relative weights, smoking and dietary habits, and physical activities. The MI survivors had significantly higher concentrations of total and VLDL-triglyceride and total and LDL-cholesterol than the control subjects. The differences in HDL-cholesterol, and total apolipoproteins A-1 and B were of borderline significance. HDL₂ was significantly lower and LDL₂ was higher in the MI survivors. There was no difference in HDL₃. The differences in lipoprotein subfractions could be ascribed to differences in cholesterol, phospholipid and proteins, but not in triglyceride. The data suggest that the minor HDL₂ subfraction shows a closer association with established coronary heart disease than does total HDL-cholesterol. The increased LDL-cholesterol concentration in the MI survivors can be ascribed at least partly to an increase in the major subfraction, LDL₂.     

Regional and global left ventricular function during intra-aortic balloon counterpulsation in patients with acute myocardial infarction shock

We evaluated the improvement in hemodynamic and left ventricular (LV) function in 15 patients with acute myocardial infarction and cardiogenic shock, who were treated with intraaortic balloon counterpulsation (IABP). They were studied by flow-directed right heart catheterization and nuclear angiography. IABP decreased LV end-diastolic volume from 134 to 114 ml and LV end-systolic volume from 100 to 72 ml. LV stroke volume increased from 34 to 42 ml and cardiac output from 3.0 to 3.6 L/min. Global LV ejection fraction increased from 27.6% to 36.1%, and this was due to improvement in regional ejection fraction in ischemic areas. Pulmonary capillary wedge pressure and pulmonary blood volume decreased. Right ventricular ejection fraction also increased significantly. IABP improved LV function in acute myocardial infarction.     

An analysis of electrocardiographic,radiographic, and vectorcardiographic findings in patients with implanted cardiac pacemakers

In patients with implanted cardiac pacemakers, the radiological appearances, and the configuration of the 12-lead ECG have been conventionally used both to locate the site of the electrode implantation and to diagnose electrode placement errors. These techniques have limitations, and in the present study vectorcardiographic data derived from the pacemaker stimulus and the spread to ventricular depolarization has been added to improve accuracy. Three hundred patients with implanted cardiac pacemakers were studied. Unusual QRS complexes as determined from the 12-lead ECG were found in 37 (12%) and the position of the pacemaker electrodes determined from the lateral chest x-ray was outside normal (R.V. apex) in 61 patients (20.3%). A combined interpretation of the ECG, chest x-ray, and the vectorcardiogram agreed on positioning (correct or incorrect) in all but 17 patients (5.6%). Three patients had a perforated right ventricle, while further study of the other 14 suggested malpositioning of the catheter electrode in the right ventricle or in the coronary venous system. An analysis of the ECG patterns, x-ray appearances, and vectorcardiograms is presented with respect to the diagnosis of pacemaker electrode placement errors and a logical tree for establishing the position of the pacemaker is introduced.     

Sinus and A-V nodal dysfunction following myocardial infarction.

A patient in whom syncopal episodes occurred following an inferior myocardial infarction is described. Electrocardiographic monitoring revealed periods of profound sinus bradycardia and AV block during syncope. In addition, transient spontaneous prolongations of the PR interval due to AV nodal delay and episodes of atrial fibrillation also occurred. Sinus node recovery time following atrial overdrive was within normal limits. Symptoms disappeared following the insertion of a permanent, demand pacemaker. The onset of symptoms following myocardial infarction suggests that dysfunction of the sino-atrial and AV nodes may have been the result of ischemic damage during the infarction.     

Heparin therapy: A randomized prospective study

Eighty patients were assigned randomly either to continuous or to intermittent heparin therapy, with control by the Lee-White Clotting Time (LWCT). Major bleeding complications occurred in 7.5 per cent and minor complications in 18 per cent of the entire group. The incidence of major bleeding complications in the continuous group (5 per cent) did not differ significantly from the incidence in the intermittent group (10 per cent). In contrast, bleeding complications were significantly more frequent in patients with soft-tissue trauma due to such procedures as thoracenteses and cut-downs, vascular damage due to other causes, and LWCTs over 35 minutes for 2 consecutive days.The incidence of bleeding complications appear to be the same in patients receiving intermittent as in those receiving continuous heparin therapy. Thoracenteses, cut-downs, and other forms of soft-tissue injury predispose to bleeding complications while laboratory monitoring with the LWCT may help to reduce bleeding complications.     

Early diagnosis of pericarditis in acute myocardial infarction

Pericarditis complicating acute myocardial infarction assumes increasing importance in this era of quantitating infarct size by precordial ST segment mapping. Early recognition of this complication avoids diagnostic and therapeutic errors. In this study we looked for factors that could alert to the early diagnosis of pericarditis, such as ST elevation measured within 24 hours from onset, extent of CPK, LDH, and SGOT elevation, as well as degree of pump dysfunction. ST segment elevation in millimeters on admission seemed to be one factor that was of predictive value in this condition.Pericarditis occurred in three forms: (1) within a few hours from the onset of myocardial infarction and this form seems to carry a high mortality rate; (2) a more common variety occurs within 24 to 72 hours from onset and carries a higher mortality rate than matched controls; and (3) the late syndrome of Dressler's, not observed in our series. Aside from increased incidence of heart failure, other complications of myocardial infarction and the coronary risk factors were not significantly higher in patients with pericarditis. Salicylate treatment offers immediate relief in the majority of patients.     

Effects of cardiac rehabilitation after myocardial infarction: Changes in coronary risk factors and long-term prognosis

Prognosis during 5 years of follow-up after first myocardial infarction (MI) in a group of men (aged 40 to 55 years) was related to risk factors determined at the time of MI. Progression of coronary artery disease (CAD) was measured by the occurrence of severe angina pectoris, recurrent myocardial infarction, and cardiac death. Only smoking and serum cholesterol level influenced prognosis. It was possible to identify a subgroup (patients smoking less than 20 cigarettes/day and having a cholesterol level of less than 7.0 mmoles/L) with low risk for progression of CAD. A randomly applied 6-week rehabilitation program shortly after MI was associated with a 50% decrease in progressive CAD when compared to the control group. Since only a slight decrease in cholesterol levels was found in the rehabilitation group, a direct effect of the rehabilitation program could thus not be excluded because the second important risk factor, smoking, did not show differences between the two groups. The smoking habits at the time of MI determined the continuation of cigarette smoking and rehabilitation did not influence smoking habits.     

Comparison of ventricular parasystole with other dysrhythmias after acute myocardial infarction

Three hundred and sixty-nine patients suffering from a recent myocardial infarction were studied over a period of 16 months in a coronary-care unit. Particular attention was paid to ventricular arrhythmias and especially ventricular parasystole. Ventricular parasystole was found in 4 per cent of the patients, identification being helped by the recording of long strips of ECG at slow speed when ventricular ectopic activity was noted.The study has shown that ventricular parasystolic rhythms after acute myocardial infarction are probably benign in contrast to most other ventricular arrhythmias which are associated with an increased mortality.     

Bundle branch block in acute myocardial infarction

The management of patients with acute myocardial infarction complicated by bundle branch block is a significant clinical problem and represents 8% to 13% of patients with acute infarction. This study reviews the records of 606 patients with myocardial infarction admitted to our coronary care unit. Forty-seven (8%) had complete bundle branch block. The risk of developing high-degree AV block in these 47 patients was reviewed. There are no established therapeutic guidelines for patients with pre-existing bundle branch block and left bundle branch block in acute myocardial infarction. We found a high risk of progression in patients with pre-existing bifascicular block in the presence of anterior wall infarction (25%) as well as in patients with left bundle branch block with acute anterior wall infarction (100%). On the basis of our data and careful review of the literature, we recommend prophylactic pacemaker insertion in these high-risk groups.     

Left ventricular gallop sound and acute myocardial infarction

A ventricular gallop sound, pulmonary râles, and cardiogenic shock have important prognostic implications in patients with acute myocardial infarction. The purpose of this study was to examine the relationship between VGS and death in myocardial infarction. A VGS was audible in 63 of 156 patients (40 per cent) with proved myocardial infarction admitted to a Myocardial Infarction Research Unit during a 24 month period. Fifty-three patients were studied hemodynamically, and 25 of 27 patients with an S₃ gallop demonstrated an abnormally elevated pulmonary artery enddiastolic pressure greater than 12 mm. Hg. Hospital deaths occurred in 40 per cent of patients with a VGS versus 15 per cent of those without this auscultatory finding. Seventy-five per cent of patients in cardiogenic shock died, but a VGS was not significantly associated with death in this group. Although in all patients a VGS was associated with increased mortality rate, deaths were not due to cardiogenic shock. This study confirms the need for hemodynamic monitoring in patients with acute myocardial infarction who exhibit a VGS as evidence of left ventricular power failure. Treatment should be based upon both clinical observations and continued evaluation of the hemodynamic alterations associated with left ventricular power failure.