Left ventricular function in patients with coronary heart disease in the presence or absence of angina pectoris during exercise radionuclide ventriculography

This study compares left ventricular (LV) performance during exercise in patients with angiographically documented coronary artery disease (CAD) based on the presence or absence of angina pectoris during the index exercise tests. The patients were divided into 2 groups: Group I included 31 patients who had angina pectoris during the test and Group II included 43 who did not. Multivessel CAD was present in 21 patients (68%) in Group I and 26 patients (60%) in Group II (difference not significant [NS]). There were no significant differences between the 2 groups in age, sex, history of diabetes mellitus, history of myocardial infarction and in the exercise duration, work load, heart rate and systolic blood pressure. Exercise-induced ST-segment depression was present in 48% of the patients in Group I and in 40% in Group II (NS). The mean LV ejection fraction at rest was 52 ± 12% in Group I and 50 ± 17% in Group II (NS). There were significant differences in the 2 groups in the change from rest to exercise in ejection fraction (?4.5 ± 7.6% in Group I vs 1 ± 9.4% in Group II, p < 0.01), end-systolic volume (29 ± 38 ml in Group I vs 9 ± 23 ml in Group II, p < 0.005), the change in systolic blood pressure-to-end-systolic volume ratio (?0.1 ± 0.5 mm Hg/ml in Group I vs 0.3 ± 1.1 mm Hg/ml in Group II, p < 0.05), and wall motion score (?0.4 ± 0.6 in Group I vs 0.09 ± 0.7 in Group II, p < 0.05).Thus, asymptomatic myocardial ischemia may occur in patients with extensive CAD and be associated with abnormal exercise LV function; however, patients with symptomatic CAD have worse exercise LV function than those with asymptomatic CAD.     

Effects of procainamide on strength-interval relations in normal and chronically infarcted canine myocardium

The effects of procainamide on strength-interval relations in normal and chronically infarcted canine myocardium were determined in nine adult mongrel dogs susceptible to sustained ventricular tachyarrhythmias. The dogs were studied at 3 to 30 days after two stage occlusion and reperfusion of the mid left anterior descending coronary artery. Unipolar cathodal stimulation (pulse duration 2 ms, drive cycle length 300 ms) was used to evaluate excitability and refractoriness at a total of 19 normal and 22 infarct sites both before and 15 to 30 minutes after intravenous infusion of procainamide, 20 to 25 mg/kg body weight. The electrophysiologic effects of procainamide were evaluated at the time of the plateau phase of procainamide's antiarrhythmic activity in this model. At normal sites, procainamide had only a minimal effect on the mean diastolic excitability threshold (increased from a mean [± standard deviation]of 0.07 ± 0.02 to 0.08 ± 0.02 mA [probability (p) = not significant (NS)], the mean effective refractory period (increased from 137 ± 10 to 139 ± 11 ms [p = NS]) and the mean ventricular refractory period at twice diastolic threshold (increased from 156 ± 12 to 163 ± 16 ms [p <0.01]). At infarct sites, the mean diastolic excitability threshold was similarly unchanged after procainamide (from 0.57 ± 1.13 to 0.57 ± 1.09 mA [p = NS]), but both the mean effective refractory period (from 142 ± 17 to 159 ± 27 ms [p <0.001]) and the mean ventricular refractory period at twice diastolic threshold (from 166 ± 25 to 187 ± 33 ms [p <0.001]) were moderately prolonged. In addition, dispersion of refractoriness between normal and infarct sites as well as within areas of infarcted myocardium was often either unchanged or increased rather than decreased by procainamide.

Thus, the antiarrhythmic activity of procainamide in this canine model of chronic myocardial infarction was not explained by an effect on the excitability or refractoriness of normal myocardium, by changes in the diastolic excitability of infarcted tissue or by an effect on the dispersion of refractoriness. The most prominent effect of procainamide was to decrease the excitability of abnormal myocardium during the relative refractory period and to prolong the refractoriness of abnormal myocardium.     

Usefulness of a state-legislated,comparative database to evaluate quality in colorectal surgery

PURPOSE: Colorectal surgery, a high-volume procedure, has been targeted for performance improvement to reduce length of stay. Specific postoperative quality indicators and readmission rates should be analyzed concomitantly to assure that adverse events are not associated with earlier discharge. METHODS: From July 1, 1990, to June 30, 1997, 1,218 consecutive patients who underwent transabdominal colorectal surgery were analyzed for length of stay, mortality, morbidity, and discharge disposition. Each patient was assigned an Admission Severity Group rating 0 to 4 using a hospital-based state-legislated software system (Atlas) to validate comparative performance internally and externally. Readmission data within 120 days of discharge were available for the last 678 consecutive patients from July 1, 1993, to June 30, 1997, using Lastword (computerized medical records). RESULTS: The annual frequencies of the 1,218 procedures were 173, 183, 175, 146, 167, 189, and 185, respectively, from July 1990 through June 1997. Severity distribution was 32 for Admission Severity Group 0, 517 for Admission Severity Group 1, 540 for Admission Severity Group 2, 128 for Admission Severity Group 3, and 1 for Admission Severity Group 4, with no annual difference (P=0.012). There was a significant reduction in total length of stay of 3.1 (12.9–9.8) days during the seven years (P=0.001). The overall operative mortality rate was 1.4 percent, and the morbidity was 2.6 percent, with no annual differences (P=0.655 andP=0.033, respectively). The disposition to home did not change (P=0.21). Of the 678 patients followed up for readmission, 100 (14.7 percent) were readmitted within 120 days, with no annual difference (P=0.302). CONCLUSION: Mortality, morbidity, disposition, and readmission rates were not affected by a decreased length of stay after colorectal surgery.Presented at the Research Forum at the meeting of The American Society of Colon and Rectal Surgeons, San Antonio, Texas, May 2 to 7, 1998.     

Noninvasive detection of multivessel disease after myocardial infarction by exercise radionuclide ventriculography

The ability of exercise radionuclide ventriculography to detect multivessel coronary artery disease in patients who survived a single myocardial infarction was assessed. Seventy-four patients who had had myocardial infarction at least 8 weeks earlier underwent cardiac catheterization and exercise radionuclide ventriculography. Thirty-eight patients had had an inferior infarction: 25 with multivessel disease and 13 with single vessel disease of the right coronary artery. Thirty-six patients had had an anterior infarction: 26 with multivessel disease and 10 with single vessel disease of the left anterior descending coronary artery.

Among patients with anterior infarction there was no significant difference between patients with single vessel disease and patients with multivessel disease with regard to resting ejection fraction, exercise ejection fraction, and the mean change from rest to exercise. Patients with single vessel disease had a decrease in ejection fraction from rest to exercise of 2.2 ± 2.7% units (mean) ± standard error [SE]), compared with a decrease of 5.4 ±1.3% units in those with multivessel disease (p = not significant [NS]). Seventeen of 26 (65%) patients with multivessel disease and 6 of 10 (60%) with single vessel disease had a decrease in ejection fraction of at least 5 percentage units (p = NS).

In patients with inferior infarction there was no difference in the mean resting ejection fraction in those with single vessel disease (53 ± 2%) compared with those with multivessel disease (50 ±2%); however, the mean exercise ejection fraction in patients with single vessel disease (57 ± 3%) was significantly higher (p < 0.005) than that in patients with multivessel disease (45 ± 2%). Sixteen of the 25 patients with multivessel disease (64%) but only 1 patient with single vessel disease (7.7%) had a decrease in ejection fraction of at least 5 percentage units (p < 0.001).

A new wall motion abnormality developed in 8 patients with anterior infarction and 11 with inferior infarction with multivessel disease and none with single vessel disease. The sensitivity and specificity in predicting multivessel disease using the criteria of the development of a new wall motion abnormality or a decrease in ejection fraction with exercise of at least 5 percentage units were 80 and 92% for the patients with inferior infarction, but only 69 and 40% for the patients with anterior infarction.

These results suggest that exercise radionuclide angiography can be used to discriminate between single and multivessel disease after inferior myocardial infarction. For patients with anterior infarction, only a new abnormality in wall motion accurately predicts multivessel disease, but this occurred in only one third of such patients.     

Pulmonary varix regression after mitral valve replacement.

Pulmonary varix is a rare finding; only 35 documented cases have been reported. The first case was described in 1843 as an icidental postmortem finding. The first clinical diagnosis was not made until 1951. In more than half of the 35 cases, the varix was present in the absence of congenital and acquired heart disease. Six patients have had concomitant mitral rheumatic heart disease. This communication describes the second patient with rheumatic mitral regurgitation in whom the pulmonary varix became radiographically invisible after prosthetic mitral valve replacement.     

Electrophysiologic residua and sequelae of surgery for congenital heart defects

Postoperative arrhythmias may occur in any patient who undergoes intracardiac surgery for a congenital heart defect. The correction of certain intracardiac heart defects predisposes to a large incidence of cardiac arrhythmias. Ventricular arrhythmias and conduction disturbances are seen after correction of tetralogy of Fallot, ventricular septal defect and atrioventricular canal defect. Supraventricular arrhythmias and sinus nodal dysfunction may be seen after surgery for transposition of the great arteries or atrial septal defect. The identification, evaluation and treatment of these patients are discussed.     

Increased R-wave amplitude induced by acute myocardial ischemia in the dog: A predictor of malignant ventricular arrhythmias

The ability of an increase of 25 % or greater in the sum of R-wave amplitudes in leads X, Y, Z, L₂, and V₅ to predict the occurrence of malignant ventricular arrhythmias (10 or more ventricular premature beats/min, ventricular tachycardia [5 or more consecutive premature beats], and/or fibrillation) was evaluated in 17 dogs during experimental acute myocardial ischemia. Each dog underwent a 15 minute ligation of the left anterior descending coronary artery followed by reperfusion and after recovery, 2 hours later, a 15 minute ligation of the circumflex coronary artery. During ligation of the left anterior descending coronary artery, 12 of 17 dogs (71%) showed no R-wave increase and no arrhythmias (true-negative response). In 5 (29%) of 17 dogs malignant ventricular arrhythmias developed: 2 of 5 (40%) dogs with arrhythmias had a concomitant R-wave increase (true-positive response), and 3 of 5 (60%) with arrhythmias had a less than 25% increase in R-wave amplitude (false-negative results). During circumflex coronary artery ligation, 13 of 17 (76%) dogs showed both R-wave increases and arrhythmias (true-positive response). Four (24%) of 17 dogs had no arrhythmias: 3 of 4 (75%) with no arrhythmias also had a less than 25% increase in R-wave amplitude (true-negative response), whereas 1 of 4 (25%) dogs with no arrhythmias had an increase in R-wave amplitude (false-positive response). In dogs with both arrhythmias and R-wave increases, R-wave changes preceded the onset of arrhythmias by a mean (± standard deviation) of 1 minute 27 seconds (± 43 seconds). Overall, R-wave increases were highly sensitive (83%), specific (94%), and predictive (94%) for the occurrence of malignant ventricular arrhythmias during experimental acute myocardial ischemia.     

Lack of correlation between exercise capacity and indexes of resting left ventricular performance in heart failure

Symptoms of congestive heart failure occur most commonly during exercise, but cardiac performance is usually quantitated at rest. The relation between exercise capacity and measurements of cardiac performance at rest is little known. Treadmill exercise was performed in 21 patients with heart failure due to cardiomyopathy. Exercise duration averaged 9.1 ± 0.7 (standard error of the mean) minutes (normal value 12 or more minutes) and did not correlate with resting ejection fraction of 26.4 ± 2.7 percent (r = ?0.06). Left ventricular diastolic dimension of 6.6 ± 0.2 cm, mean velocity of circumferential fiber shortening and ratio of preejection period to left ventricular ejection time did not correlate with treadmill time (r = ?0.03). Repeat studies after treatment of heart failure also failed to show correlations between changes in exercise capacity and changes in left ventricular performance at rest. Thus, measures of left ventricular performance obtained at rest do not accurately reflect exercise tolerance and symptomatic status of patients with congestive heart failure.