Robert B. Karp

Unstable angina pectoris: National cooperative study group to compare surgical and medical therapy: II. In-Hospital experience and initial follow-up results in patients with one, two and three vessel disease

Abstract A prospective randomized study comparing intensive medical therapy with urgent coronary bypass surgery for the acute management of patients with unstable angina pectoris was carried out by nine cooperating medical centers under the auspices of the National Heart, Lung, and Blood Institute. Between 1972 and 1976, a total of 288 patients were entered into the study. All patients had transient S-T or T wave changes, or both, in the electrocardiogram during pain; 90 percent had pain at rest in the hospital, and 76 percent had multivessel coronary disease. The medically and surgically treated patients were comparable with respect to clinical, electrocardiographic and angiographic characteristics and left ventricular function. During the total study period, the hospital mortality rate was 5 percent in the surgical group and 3 percent in the medical group (difference not significant). The rate of in-hospital myocardial infarction was 17 and 8 percent in the respective groups (P In the 1st year after hospital discharge class III or IV angina (New York Heart Association criteria) was more common in medically than in surgically treated patients with one vessel disease (22 percent versus 3 percent, P The results indicate that patients with unstable angina pectoris can be managed acutely with intensive medical therapy, including the administration of propranolol and long-acting nitrates in pharmacologic doses, with adequate control of pain in most patients and no increase in early mortality or myocardial infarction rates. Later, elective surgery can be performed with a low risk and good clinical results if the patients angina fails to respond to intensive medical therapy.

Characterization of Atrial Fibrillation in Man: Studies Following Open Heart Surgery*

The nature of localized atrial activation during atrial fibrillation was characterized in 34 patients following open heart surgery. Bipolar atrial electrograms (AEG) recorded in each patient with atrial fibrillation exhibited a myriad of sizes, shapes, polarities, amplitudes, and beat‐to‐beat intervals. On the basis of the AEG morphology and the nature of its baseline, we have classified the recordings into four Types. Type I was characterized by discrete AEG complexes separated by an isoelectric baseline free of perturbation, Type II by discrete AEG complexes but with perturbations of the baseline between complexes, Type III by AEGs which failed to demonstrate either discrete complexes or isoelectric intervals, and Type IV in which AEGs of Type III alternated with periods characteristic of Type I and/or Type II. In 22 patients, the AEGs were recorded a second time, and in 11 of these patients the type of atrial fibrillation changed between the first and second recording period. An atrial flutter‐fibrillation pattern in the ECG was associated with a relatively ordered atrial activation pattern and a relatively slow atrial rate. Human atrial fibrillation is not an electrophysiologically homogeneous process when compared among different patients or ad seriatim in the same patient.

Neuronal and adrenomedullary catecholamine release in response to cardiopulmonary bypass in man.

Cardiopulmonary bypass (CPB) alters systemic hemodynamics and affects several biochemical systems involved in cardiovascular regulation. We investigated the changes in levels of circulating epinephrine (E) and norepinephrine (NE) and related them to events during CPB. Twenty-eight patients undergoing various surgical procedures were studied. Plasma E and NE were determined by radioenzymatic assay at eight stages of the operation. A ninefold increase in arterial E (from 75 ± 13 to 708 ± 117.3 pg/mI) occurred from prebypass (stage 1) measurements to the end of aortic cross-clamping (stage 4). The values at stage 4 were significantly higher (p < 0.05) than at all other stages. E decreased rapidly, to 360 84.3 pg/ml, rafter myocardial and pulmonary reperfusion (stage 5). Arterial NE increased twofold from stage 1 to stage 4 (from 426 66.9 to 825 84.2, p < 0.05). The increase in NE from initial CPB values (stage 2) to 30 minutes of aortic cross-clamping (stage 3) was associated with an increase in mean blood pressure (r 0.51, p = 0.02). The peak increases in catecholamines occurred when the heart and lungs wereexcluded from the circulation, which suggests that either or both contributed to the increase. Because the increase in E was markedly greater than that in NE, the predominant humoral response to CPB appears to be adrenomedullary release of E. This significant increase in catecholamines could jeopardize myocardial protective measures duringCPB.

Factors and Their Influence on Regional Cerebral Blood Flow during Nonpulsatile Cardiopulmonary Bypass

Abstract In this study we examined the relationship of regional cerebral blood flow (CBF) to mean arterial pressure, systemic blood flow, partial pressure of arterial carbon dioxide (PaCO 2 ), nasopharyngeal temperature, and hemoglobin during hypothermic nonpulsatile cardiopulmonary bypass (CPB). Regional CBF was determined by clearance of xenon 133 in 67 patients undergoing coronary bypass grafting procedures. There was a significant decrease in regional CBF (55% decrease) during CPB, with nasopharyngeal temperature and PaCO 2 being the only two significant factors ( p 2 did not significantly affect regional CBF. We conclude that cerebral autoregulation is retained during hypothermic CPB. Under the usual conditions of CPB, variations in flow and pressure are not associated with important physiological or detrimental clinical affects.

Pathogenesis of paroxysmal hypertension developing during and after coronary bypass surgery: A study of hemodynamic and humoral factors

A prospective study of hypertension first appearing during and after saphenous vein bypass coronary surgery was performed in 28 patients to examine the incidence, hemodynamics and mechanism of this problem. In 15 patients (54 percent) new hypertension developed (mean arterial pressure greater than 107 mm Hg), characterized by increased peripheral vascular resistance and unchanged cardiac output within 1 hour after surgery. These 15 patients had a longer history of angina of greater severity, but also had relatively well preserved ventricular myocardium. Because plasma renin activity was depressed in patients in the hypertensive group, activation of the renin-angiotensin system was not important in the pathogenesis of this postoperative hypertension. The expected decrease in total peripheral resistance at the onset of cardiopulmonary bypass was observed in all patients, but later during bypass the peripheral resistance increased in all patients in association with a rise in plasma epinephrine levels. Patients who had hypertension postoperatively had a greater increase in arterial pressure and total peripheral resistance during cardiopulmonary bypass than did those with normal postoperative blood pressure. An elevation in plasma epinephrine and norepinephrine concentration, suggesting enhanced sympathoadrenal responsiveness to the challenge of cardiopulmonary bypass, was characteristic of the hypertensive group. This evidence of enhanced sympathetic activity during surgery may be a useful predictor of the development of postoperative hypertension.

Unstable angina pectoris: National cooperative study group to compare medical and surgical therapy

A preliminary report is presented of a prospective randomized trial conducted by eight cooperative institutions under the auspices of the National Heart and Lung Institute to compare the effectiveness of medical and surgical therapy in the management of the acute stages of unstable angina pectoris. To date 150 patients have been included in the randomized trial, 80 assigned to medical and 70 to surgical therapy; the clinical presentation, coronary arterial anatomy and left ventricular function in the two groups are similar. Some physicians have been reluctant to prescribe medical or surgical therapy by a random process, and the eithical basis of the trial has been questioned. Since there are no hard data regarding the natural history and outcome of therapy for unstable angina pectoris, randomization appears to provide a rational way of selecting therapy. Furthermore, subsets of patients at high risk may emerge during the process of randomization. The design of this randomized trial is compared with that of another reported trial. Thus far, the study has shown that it is possible to conduct a randomized trial in patients with unstable angina pectoris, and that the medical and surgical groups have been similar in relation to the variables examined. The group as a whole presented with severe angina pectoris, either as a crescendo pattern or as new onset of angina at rest, and 84 percent had recurrence of pain while in the coronary care unit and receiving vigorous medical therapy. It is anticipated that sufficient patients will have been entered into the trial within the next 12 months to determine whether medical or surgical therapy is superior in the acute stages of unstable angina pectoris.Abstract A preliminary report is presented of a prospective randomized trial conducted by eight cooperative institutions under the auspices of the National Heart and Lung Institute to compare the effectiveness of medical and surgical therapy in the management of the acute stages of unstable angina pectoris. To date 150 patients have been included in the randomized trial, 80 assigned to medical and 70 to surgical therapy; the clinical presentation, coronary arterial anatomy and left ventricular function in the two groups are similar. Some physicians have been reluctant to prescribe medical or surgical therapy by a random process, and the ethical basis of the trial has been questioned. Since there are no hard data regarding the natural history and outcome of therapy for unstable angina pectoris, randomization appears to provide a rational way of selecting therapy. Furthermore, subsets of patients at high risk may emerge during the process of randomization. The design of this randomized trial is compared with that of another reported trial. Thus far, the study has shown that it is possible to conduct a randomized trial in patients with unstable angina pectoris, and that the medical and surgical groups have been similar in relation to the variables examined. The group as a whole presented with severe angina pectoris, either as a crescendo pattern or as new onset of angina at rest, and 84 percent had recurrence of pain while in the coronary care unit and receiving vigorous medical therapy. It is anticipated that sufficient patients will have been entered into the trial within the next 12 months to determine whether medical or surgical therapy is superior in the acute stages of unstable angina pectoris.

P waves during ectopic atrial rhythms in man: a study utilizing atrial pacing with fixed electrodes.

Threshold bipolar pacing was performed from one of 12 selected atrial sites with temporary implanted electrodes in 69 patients following open-heart surgery in order to study P wave polarity and morphology and the P-R interval during paced ectopic atrial rhythms. A negative P wave was recorded in lead I only with pacing the left atrium and only when pacing near the left pulmonary veins. A positive bifid P wave in V1 was recorded only with left atrial pacing and only when pacing was near the inferior pulmonary veins and coronary sinus. P wave polarity and morphology were otherwise of no use in localization of the origin of the impulse in these studies. The pacing stimulus to P wave interval was found to vary between 10 and 54 msec, making the duration of the P-R interval an unreliable indicator of the site of origin of the paced impulse. Although the relation of these paced rhythms to spontaneously occurring ectopic rhythms is unclear, the previously published criteria for localizing ectopic atrial rhythms are again demonstrated to be unreliable. P wave polarity and morphology and the P-R interval are of limited value in ascertaining the origin of ectopic atrial rhythms in man.

Evaluation of cardiac transplant candidates: Preliminary observations

Abstract Acting in a consultation-liaison role, the authors assisted the surgical team with preoperative and postoperative evaluation of psychiatric complications, and with postoperative management, for the eight cardiac transplant patients described in vignettes in this article. The incidence of depression, anxiety, and organic mental disorders was high, leading to the recommendation that a psychiatric team be regularly involved with assessment and management of the transplant patient before and after the operation

Replacement of the Ascending Aorta and Aortic Valve with a Composite Graft: Results in 25 Patients

Our experience with combined replacement of the ascending aorta and aortic valve with a composite prosthetic valve-Dacron tube graft in 25 patients from September, 1974, to December, 1976, is reviewed. The technique involves suture of the composite graft to the aortic annulus, to the aortic tissue surrounding the coronary ostia, and to the distal ascending aorta, closing the aortic wall over the graft before discontinuing cardiopulmonary bypass. Annuloaortic ectasia was the most common indication for operation (15 patients). Perfusion of the coronary arteries was used in the first 15 patients. In the remaining 20, internal and external myocardial cooling with one period of ischemic arrest (average, 67 minutes) was used. There was 1 hospital death (4%), and there have been 3 late deaths (12%) in the 27-month follow-up period. This technique appears to be applicable to most types of aneurysmal disease of the proximal ascending aorta associated with aortic valve incompetence. All aneurysmal tissue from the aortic annulus to the innominate artery is excluded, bleeding through the graft is eliminated, operative time is reduced, and the late results have been satisfactory to date.

Unstable angina pectoris: National cooperative study group to compare surgical and medical therapy: III. Results in patients with S-T segment elevation during pain

Abstract A prospective randomized study comparing intensive medical therapy with urgent coronary bypass surgery for the acute management of patients with unstable angina pectoris was carried out by nine cooperating medical centers under the auspices of the National Heart, Lung, and Blood Institute. Between 1972 and 1976, a total of 288 patients were entered into the study; 79 of these (27 percent of the total study group) with 70 percent or more fixed obstruction in one or more coronary arteries had episodes of pain at rest associated with transient S-T segment elevation. Forty-two were randomized to medical and 37 to surgical therapy. The hospital mortality rate was 4.8 percent for the medical and 5.4 percent for the surgical group (difference not significant). The rate Of in-hospital myocardial infarction was 12 percent in the medical and 14 percent in the surgical group (difference not significant). During the 1st and 2nd years of follow-up, 25 percent in the medical and 15 percent in the surgical group complained of New York Heart Association class III or IV angina (difference not significant). During an average follow-up period of 42 months 45 percent of the medically treated patients later underwent surgery to relieve unacceptable angina. In the medical group 65 percent were working full- or part-time at the end of 1 year and 61 percent at the end of 2 years of follow-up; comparable figures for the surgically treated group were 63 and 68 percent. The results indicate that patients with unstable angina pectoris with transient S-T segment elevation during pain at rest with fixed obstruction of 70 percent or more in one or more coronary arteries do not differ significantly from patients with pain at rest associated with transient S-T segment depression or T wave inversion. The condition of such patients can be stabilized, and they can be managed with a maximal medical program including propranolol and long-acting nitrates in pharmacologic doses with good control of pain in most and no increase in rate of early mortality or myocardial infarction. Later, elective surgery can be performed with a lower risk and good clinical results if the patients angina fails to respond to intensive medical therapy.