Nicholas T. Kouchoukos

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.

Coronary anatomy and arteriography in patients with unstable angina pectoris

Abstract A prospective series of 188 patients with the syndrome of unstable angina pectoris undergoing coronary arteriography was reviewed to determine the spectrum of anatomic coronary artery disease, suitability for coronary revascularization and in-hospital morbidity and mortality. Thirty-two patients demonstrated normal to moderately diseased coronary arteries. None of these patients sustained myocardial infarction or died. Twenty patients (10.6 percent) had normal coronary arteriograms. Of the 156 patients having severe coronary artery disease (greater than 70 percent stenosis), 20 patients (13 percent) had left main coronary artery disease. One hundred forty-two patients (91 percent) were potential candidates for coronary surgery; 14 were not candidates because of distal vessel disease or poor left ventricular function. During cardiac angiography or in the subsequent hospital period 12 patients sustained a myocardial infarction and 7 of these died. Of these seven, six had left main coronary artery disease and one had three vessel disease. In three patients who died (1.9 percent of those with severe coronary artery disease) the death may have been related to cardiac catheterization because evidence of myocardial necrosis began within 24 hours of study. Thus, patients with the syndrome of unstable angina pectoris usually presented with severe coronary artery disease and were candidates for coronary revascularization. The anatomic severity of coronary artery disease appeared to be the most important factor contributing to myocardlal infarction or death after cardiac catheterization. Mortality after catheterization was primarily associated with left main coronary artery disease.

Estimation of Stroke Volume in the Dog by a Pulse Contour Method

A method for estimating the stroke volume (SV) from the systolic area of a single-channel record of the central aortic pressure has been tested in 12 anesthetized open-chest dogs. The formula used was SV = K·Psa·(1 + Ts/Td), where Psa is the area under the systolic part of the curve above end-diastolic pressure, Ts and Td are the durations of systole and diastole, respectively, and K is an arbitrary constant derived from measurement of an initial SV by electromagnetic flowmeter in each dog and used thereafter without change, in that dog. In the 12 dogs, 541 simultaneous determinations of SV by the pressure contour and electromagnetic flowmeter methods were compared under normal and altered circulatory conditions employing 12 different interventions. The total range of SV was 2.4 to 28.1 ml, of heart rate 35 to 207/min, and of mean arterial pressure 24 to 166 mm Hg. The overall correlation coefficient (r) was 0.928 with a regression line y = 1.04x + 0.21 ml (SE) of estimate, ±17.4%. Except for three sympathomimetic drugs, the r values for all other interventions ranged from 0.93 to 0.99. These observations compare favorably with those of previously reported pulse contour methods. The windkessel origin of the formula is noted, and a new derivation from a modification of the “water-hammer” equation is given.

Hydroxyethyl Starch versus Albumin for Colloid Infusion Following Cardiopulmonary Bypass in Patients Undergoing Myocardial Revascularization

Hydroxyethyl starch or hetastarch (HES), a synthetic colloid for intravascular volume expansion, was compared with albumin after coronary artery operations in 30 patients (15 in each study group). Cardiac index, atrial pressures, heart rate, and systolic blood pressure were similar in both groups. There were no differences in cumulative urine output at 24 hours or in weight change during the first 7 postoperative days. Values for colloid osmotic pressure, as well as for this variable minus left atrial pressure, were lowest soon after bypass but returned to baseline within 4 hours, with no difference between groups in the first 24 hours or 7 days after operation. Coagulation variables were similar, but prothrombin and partial thromboplastin times were higher 12 hours postoperatively and fibrinogen level was lower 7 days postoperatively in the patients receiving HES. There was no clinical evidence of excessive bleeding, although cumulative chest drainage at 12 and 24 hours was slightly higher in the HES group (p = 0.09 and 0.08, respectively). We conclude that hetastarch is a safe and effective colloid to use following coronary operations.

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.

Considerations in Selection and Management of Patients Undergoing Valve Replacement with Glutaraldehyde-Fixed Porcine Bioprostheses

From November, 1973, through June, 1978, 428 operations in 425 patients were performed for replacement of aortic, mitral, or aortic plus mitral valves, utilizing 277 Hancock and 180 Carpentier-Edwards bioprostheses. Actuarially determined survival at 36 months was similar for all three groups and compared favorably with our experience with the Björk-Shiley prosthesis. Certain patient-related variables influencing late survival were identified by multivariate analysis and included previous operation for congenital heart disease, coronary artery bypass grafting in nonaortic valve replacement, race (black), age at operation, and New York Heart Association Functional Class. A small but definite incidence of thromboembolism occurred in all three groups, again similar to our experience with the Björk-Shiley prosthesis. Multivariate analysis identified four factors influencing risk of thromboembolism: previous cardiac operation, age, double-valve replacement, and rhythm at discharge. Valve degeneraation occurred, primarily in children and young adults. Over the medium term, the porcine bioprosthesis compared favorably with mechanical prostheses in terms of survival, function, and thromboembolism. Certain patient-related variables affecting survival may be modified by earlier surgical intervention.

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.

Triple-Valve Replacement: An Analysis of Eight Years' Experience

The total experience with combined aortic, mitral, and tricuspid valve replacement in 38 patients during an eight-year period ending in December, 1974, is reviewed. The hospital mortality was 23.7% (9 patients) and was influenced by the preoperative New York Heart Association Functional Class: 18%(5 of 28 patients) in Class III and 40%(4 of 10) in Class IV. Intraoperative myocardial injury was the other important factor affecting hospital mortality. The majority of late deaths were related to cardiac causes. The five-year survival was 53% (20 patients) for the entire group and 62% (17 patients) for the Class III patients. At latest follow-up (mean, 44 months), 22 (76%) of the hospital survivors had improved by at least one functional class. It appears that surgical intervention before patients reach Class IV status should give better early and long-term results. Our current indications for tricuspid valve replacement as opposed to repair are presented.