Postoperative arrhythmias after coronary artery and cardiac valvular surgery detected by long-term electrocardiographic monitoring.

Twenty-four hour long-term electrocardiographic recordings were used to supplement routine perioperative monitoring to determine the frequency and significance of arrhythmias occurring after coronary artery bypass graft surgery and cardiac valve replacement. Patients underwent “ambulatory” electrocardiographic monitoring for 24 hours before surgery and on the first and fifth days after discharge from intensive care.New arrhythmias occurred in 26 of 50 patients (52 per cent) after coronary artery bypass graft surgery and in six of 15 patients (40 per cent) after valve replacement. This high frequency of arrhythmia detection was directly attributable to the use of long-term electrocardiography. New atrial arrhythmias were common after both valvular and coronary artery bypass graft surgery (44 per cent and 38 per cent of patients, respectively). Ventricular arrhythmias were uncommon preoperatively in both groups but occurred frequently after coronary artery bypass graft surgery (36 per cent). Arrhythmias contributed to morbidity but not to mortality in this series.These results suggest that new atrial arrhythmias occurring after coronary artery bypass graft or valvular surgery may be related more to the immediate intrathoracic sequelae of surgery than to a specific underlying cardiac lesion, in contrast to ventricular arrhythmias which may be more specific for patients with ischemia. Long-term electrocardiographic recording is a useful technique to supplement routine methods of perioperative electrocardiographic monitoring.     

Traumatic pulmonary artery--left atrial fistula: an unusual case of cyanosis in an adult.

Eighteen months after sustaining a stab wound to the left upper chest, a 59-year-old man presented with cyanosis and extertional dyspnea. Arterial desaturation due to a central 22 per cent right-to-left shunt was present. A selective pulmonary arteriogram demonstrated a fistula between the main pulmonary artery and the left atrium. At operation the fistula was closed. A laceration of the pulmonic valve and healed pericarditis were present. Marked symptomatic improvement followed the operation, but a murmur of pulmonic valvular regurgitation persisted. The fistula and laceration of the pulmonic valve were probably traumatic in origin.     

Myocardial infarction in young vs old male rats: pathophysiologic changes

Young (90 days) and old (15 months) male, Sprague-Dawley rats were subjected to an acute and massive myocardial infarct by giving them two injections of a large dose of isoproterenol. The animals were autopsied at sequential time intervals to ascertain the similarities or dissimilarities in the pathophysiologic events which attend acute myocardial infarction and repair in young vs old rats. Although the signs and severity of hypotensive shock appeared to be equal, mortality was higher in the old rats, especially during the acute necrosis phase. The older rats also manifested more severe and persistent congestive heart failure, i.e., hydrothorax. Serum enzymes (CPK, SGOT, SGPT, and LDH), lipids (triglycerides, free fatty acids, and cholesterol), glucose, and BUN levels manifested a dynamic rise and fall concomitant with the induced myocardial necrosis and repair phases with distinct differences in these metabolic changes between young and old rats. Despite initially higher circulating levels of corticosterone in the old vs young rats, the older animals manifested little or no increase in circulating corticosterone levels during the acute stress of myocardial infarction. This apparent lack of adrenocortical responsiveness was accentuated by the concomitant finding of greatly hypertrophied, hemorrhagic, and lipid-depleted adrenal glands in the old rats vs a dynamic increase in circulating corticosterone levels and alterations in the weight of adrenal and thymus glands of the young rats. During the myocardial repair phase, the young rats manifested extensive endocardial fibrosis whereas the old rats displayed little or no endocardial fibrosis but copous and persistent myocardial edema and ground substance in keeping with their higher concentration of cardiac hexosamine. The pathophysiologic course of events which attends myocardial necrosis and repair is quite different in young vs old rats and may be related to the degree of responsiveness of the pituitary-adrenal axis which changes with age.     

Left ventricular compliance: mechanisms and clinical implications.

Left ventricular diastolic compliance is determined by the level of operating pressure and the diastolic pressure-volume relation. This relation is curvillinear and the slope of a tangent (operative chamber stiffness) to the pressure-volume curve increases as the chamber progressively fills. Such preload-dependent changes in compliance occur during any acute alteration in ventricular volume. At a given diastolic pressure, operative chamber stiffness (or its reciprocal, operative chamber compliance) is determined by the relative values for ventricular volume and muscle mass and by the stiffness of a unit of myocardium. Thus, there may be a leftward shift of the diastolic pressure-volume curve (increase in the modulus of chamber stiffness) as a consequence of ventricular hypertrophy or an increase in the stiffness of heart muscle itself (increase in modulus of muscle stiffness). To distinguish between hypertrophy and stiff muscle, it is useful to examine the modulus of chamber stiffness, derived from pressure-volume data, together with the volume/mass ratio of the ventricle. In this fashion, changes in the modulus of chamber stiffness that are inappropriate for a given volume/mass ratio may be attributed to changes in the material properties of the heart muscle. Examples of clinical and experimental pressure-volume studies are presented to illustrate the variety of mechanisms by which acute and chronic changes in ventricular chamber compliance evolve during the course of clinical heart disease. The pathophysiology of pulmonary congestion is best understood by considering the factors responsible for producing changes in chamber stiffness of the ventricle, whereas an examination of muscle stiffness is likely to provide more insight into the extent of irreversible functional and structural defects of the myocardium.     

Disappearance of abnormal Q waves after aortocoronary bypass surgery

Sixty-one patients were selected from 100 consecutive patients undergoing aortocoronary artery bypass. The number of vessels diseased as defined by coronary arteriography and the number of bypass grafts were recorded. Review of the preoperative electrocardiograms showed an infarct pattern in 26 of the 61 patients and analysis of the postoperative electrocardiograms revealed loss of abnormal Q waves in 3 of the 26. The pre- and postoperative clinical course of these three patients is analyzed and the extent of their coronary artery disease and number of bypass grafts compared with those of the 23 patients who had persistence of the infarction pattern and the 17 patients who manifested new Q waves. Possible explanations for the disappearance of abnormal Q waves are discussed.     

Electrocardiographic responses to atrial pacing and multistage treadmill exercise testing. Correlation with coronary arteriography

Atrial pacing was compared with multistage treadmill exercise testing in 50 patients undergoing diagnostic cardiac catheterization to determine the diagnostic sensitivity of atrial pacing. Coronary artery disease was considered significant if luminal narrowing greater than 75 percent was present. Twenty-one subjects (Group I) had no significant coronary artery disease with vessel narrowing of less than 50 percent. Twelve (Group II) had single vessel disease and 17 (Group III) had disease of two or more vessels.The mean maximal heart rate during atrial pacing was 140/min and during exercise testing was 131/min. A positive atrial pacing test result was obtained in 5 percent of patients in Group I, 17 percent of patients in Group II and 24 percent of patients in Group III. A positive multistage treadmill exercise test result was obtained in 10 percent of patients in Group I, 67 percent of patients in Group II and 94 percent of patients in Group III. These differences are statistically significant (P < 0.001). The sensitivity of atrial pacing was 20 percent compared with 83 percent for multistage treadmill exercise testing. The specificity of atrial pacing was 95 percent compared with 90 percent for multistage treadmill exercise testing. Thus, atrial pacing is an insensitive test in the diagnosis of ischemic heart disease and does not improve the diagnostic value of multistage treadmill exercise testing.     

A perioperative multidisciplinary care bundle reduces surgical site infections in patients undergoing synchronous colorectal and liver resection

Background

Surgical site infections (SSIs) are a major cause of morbidity, mortality, and healthcare costs, and patients undergoing simultaneous colorectal/liver resections are at an especially high SSI risk.

Pacemaker pseudodysfunction with a coronary sinus pacemaker

A permanent transvenous coronary sinus pacemaker functioned effectively for 22 months both as an atrial and ventricular pacemaker. Slow atrial flutter resulted in failure of the pacemaker to capture the myocardium and thus incorrectly suggested pacemaker dysfunction. Transtelephonic evaluation of this phenomenon was particularly difficult and could have resulted in unnecessary replacement of the pacing unit