Peter J. Horneffer

Stroke following coronary artery bypass grafting: A ten-year study

To identify possible risk factors for the occurrence of stroke during coronary artery bypass grafting (CABG), the cases of 3,279 consecutive patients having isolated CABG from 1974 to 1983 were reviewed. During this period, the risk of death fell from 3.9% to 2.6%. The stroke rate, however, fell initially but then rose from 0.57% in 1979 to 2.4% in 1983. Adjustment of these data for age clearly demonstrated that the risk of stroke has increased largely because of an increase in the mean age of patients undergoing CABG procedures. A case-control study involving all 56 stroke victims and 112 control patients was used to identify those risk factors significantly associated with the development of stroke in univariate analysis: increased age (63 versus 57 years in stroke patients and controls, respectively; p less than 0.0001); preexisting cerebrovascular disease (20% versus 8%; p less than 0.03); severe atherosclerosis of the ascending aorta (14% versus 3%; p less than 0.005); protracted cardiopulmonary bypass time (122 minutes versus 105 minutes; p less than 0.005); and severe perioperative hypotension (23% versus 4%; p less than 0.0001). Other variables not found to correlate with postoperative stroke included previous myocardial infarction, hypertension, diabetes mellitus, lower extremity vascular disease, preoperative left ventricular function, and intraoperative perfusion techniques. Elderly patients who have preexisting cerebrovascular disease or severe atherosclerosis of the ascending aorta or who require extensive revascularization procedures have a significantly increased risk of postoperative stroke.

Long-term results of total repair of tetralogy of fallot in childhood

Between 1958 and 1977, 170 children aged 10 years or less underwent total repair of tetralogy of Fallot at The Johns Hopkins Hospital. Follow-up data were obtained on 128 (90%) of the 143 who survived the operation at 10 to 28 years postoperatively (mean follow-up, 18 years). All patients completed an extensive questionnaire, and 59 returned for a thorough evaluation consisting of a history and physical examination, electrocardiogram, 24-hour Holter monitoring, exercise stress testing, pulmonary function testing, and two-dimensional and Doppler echocardiography. Late survival was excellent with only two of four known late deaths due to cardiac-related causes and with all 59 patients in New York Heart Association class I or II. None had cyanosis or clubbing. Normal sinus rhythm was present in 90%. One patient had complete heart block, and 75% had right bundle-branch block on the electrocardiogram. Right ventricular function was normal by echocardiography in 78%. Residual mild to moderate pulmonary stenosis was noted by Doppler study in 8 patients. Pulmonary regurgitation was present in 78%, but in only 11 patients was it graded as moderate and in none was it severe. Stress testing documented the excellent functional status of most patients, with 92% of predicted exercise time and 94% of maximum heart rate being attained. In the few who had impaired cardiac performance, this correlated best with moderate pulmonary regurgitation. Although the overall late functional status of patients undergoing repair in the first decade of life was very good, these patients need continued follow-up to assess the severity of pulmonary regurgitation and the need of possible intervention.

The epidemiology of the postpericardiotomy syndrome: a common complication of cardiac surgery

PPS is a major cause of morbidity after cardiac surgery and may cause bypass graft closure and fatal cardiac tamponade. Little is known about its incidence and cause. To better define this syndrome characterized by postoperative fever, pericardial friction rub, and pericardial pain, we used two out of three of the preceding criteria to diagnose PPS. In a prospective epidemiologic study we followed 944 consecutive patients undergoing open-heart surgery between November 1984 and November 1985. The overall incidence was 17.8%. The incidence was increased in younger patients, in those with a history of prednisone use in the past, in patients with a past history of pericarditis, those with aortic valve replacement, and in patients who received enflurane or halothane anesthesia. PPS is a common syndrome. Knowledge of risk factors associated with PPS may allow its prevention and identification of patients who warrant early and aggressive treatment.

Major stroke after coronary artery bypass surgery: changing magnitude of the problem.

Between January 1974 and December 1984, 3816 patients underwent isolated CABG at this hospital. During this 11-year interval, the number of patients having operation annually as well as the mean age at operation of the patients have increased significantly. The increase in the mean age from 51.9 years in 1974 to 59.4 years in 1984 occurred while the operative mortality rate fell significantly from 3.9% in 1974 to 2.0% in 1984. Although the overall incidence of major stroke was 1.8%, the stroke rate increased during this interval to 2.4% from 1982 to 1984. This higher stroke rate correlates significantly with the increasing age of the CABG patients, with the stroke risk five times greater for patients in their 70s compared with patients between 51 and 60 years old. Specific risk factors for the development of stroke during CABG in addition to age were examined and discussed.

Coronary artery bypass grafting in women. A ten-year perspective

Between January 1974 and December 1983, 3279 patients have undergone isolated coronary artery bypass (CAB) grafting at the Johns Hopkins Hospital. There were 639 women in this group. Women represented 18 to 22% of the patients having isolated CAB grafting throughout the 10-year period, except in 1976 when only 13% of the CAB patients were women. Mean age-at-operation for women has increased from 53.9 to 61.1 years since 1974, and was higher than the mean operative age of men during each of the 10 years. Although the oldest woman undergoing CAB grafting in 1974 was 64 years old, the eldest in 1983 was 84 years old. Except for an older mean age-at-operation for women and a higher incidence of unstable angina prior to surgery, the only other significant difference in the clinical status of female versus male CAB patients, detected by a case control analysis, was the smaller body surface area of women compared to men. Although operative mortality was significantly greater for women during most of this review period, mortality was similar during 1983 (2.6% for men versus 2.4% for women), in spite of a significantly higher incidence of unstable angina in the female group (54% for women versus 35% for men). The improved survival noted following coronary bypass grafting in women, which occurred in spite of the advancing age of the female group, supports an aggressive approach to surgical intervention in women with severe coronary artery disease.

Retrograde Coronary Sinus Perfusion Prevents Infarct Extension during Intraoperative Global Ischemic Arrest

To determine whether continuous infusion of cardioplegia retrograde through the coronary sinus could improve the salvage of infarcting myocardium, 54 pigs were utilized in a region at risk model. All hearts underwent 30 minutes of reversible coronary artery occlusion, and were divided into six groups. Group 1 served as controls and underwent two hours of coronary reflow without global ischemic arrest. The remaining five groups were subjected to 45 minutes of cardioplegia-induced hypothermic arrest followed by two hours of normothermic reflow. Group 2 had a single infusion of crystalloid cardioplegia, and Group 3 received an oxygenated perfluorocarbon cardioplegic solution initially and again after 20 minutes of ischemia. After initial cardiac arrest with crystalloid cardioplegia, all hearts in Groups 4, 5, and 6 underwent a continuous infusion of a cardioplegic solution retrograde through the coronary sinus. Group 4 received a nonoxygenated crystalloid cardioplegic solution, Group 5 received an oxygenated crystalloid cardioplegic solution, and Group 6 received an oxygenated perfluorocarbon cardioplegic solution. With results expressed as the percent of infarcted myocardium within the region at risk, Group 2 hearts, which received only antegrade cardioplegia, had a mean infarct size of 44.8 +/- 6.3%, a 2.2-fold increase over controls (p less than 0.05). While antegrade delivery of oxygenated perfluorocarbon cardioplegia (Group 3) and coronary sinus perfusion with nonoxygenated crystalloid cardioplegia (Group 4) limited infarct size to 33.6 +/- 4.7% and 35.3 +/- 5.4%, respectively, only oxygenated cardioplegia delivered retrograde through the coronary sinus (Groups 5 and 6) completely prevented infarct extension during global ischemic arrest.(ABSTRACT TRUNCATED AT 250 WORDS)

Reperfusion before Global Ischemic Arrest Improves the Salvage of Infarcting Myocardium

To study the effect of hypothermic global ischemic arrest on an evolving myocardial infarction and of perfusion of the ischemic zone or region at risk before global ischemia, 62 farm pigs underwent 15, 30, or 60 minutes of reversible coronary occlusion. Twenty-eight of these animals served as controls: reflow to the region at risk was established by removal of the coronary occluder without the addition of global ischemia. Another 26 animals had similar periods of coronary occlusion and then were placed on cardiopulmonary bypass; they underwent aortic cross-clamping and cardioplegia-induced global hypothermic arrest for 45 minutes. Eight additional pigs had two hours of reflow to the region at risk after removal of the occluder and before global ischemic arrest. When superimposed on regional ischemia, global ischemia resulted in a 6-fold increase in infarct size after 15 minutes of coronary occlusion (p less than 0.05), a 2.2-fold increase after 30 minutes of coronary occlusion (p less than 0.05), and no significant increase after 60 minutes of coronary occlusion. Reperfusion prior to global ischemia completely prevented infarct extension with 0.4% less infarction (not significant) in this group versus the controls without global ischemia. These results clearly demonstrate that infarct extension occurring when global ischemia is superimposed on regional ischemia is greatest early in infarct evolution but that reflow to the region at risk before global ischemic arrest prevents the additional infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

The Long-term Success of Skeletal Muscle in Aortic Repair

To determine the efficacy of skeletal muscle for aortic repair, 23 swine underwent repair of descending thoracic aortic defects. In one group, a vascularized muscle flap was used to patch a 2- to 3-cm aortic defect. In two other groups, a short segment of aorta was removed and a 2-cm tube graft of freshly harvested but devascularized skeletal muscle or Vicryl mesh was used to repair the aorta. Swine were followed for up to sixteen months after implantation. There were no deaths or graft-related complications in the vascularized muscle patch group, and after sixteen months, there were no stenoses or aneurysmal dilatations of the flaps. Histologically, a mature pseudointimal layer had been deposited under the muscle flap and was grossly indistinguishable from normal arterial wall. In the group that received devascularized muscle tube grafts, however, suture line dehiscences occurred in 3 of 7 animals within two weeks of operation. There were no dehiscences in the 9 recipients of a Vicryl tube graft, a finding suggesting that deposition of pseudointimal elements was rapid enough to ensure vascular integrity as the Vicryl was absorbed. Postmortem examination of these animals demonstrated stenoses ranging from 30 to 50%, thereby indicating a lack of growth in the new pseudointimal wall. These results demonstrate the long-term reliability of vascularized skeletal muscle for use in major vascular reconstruction, and suggest the beneficial effects of avoiding prosthetic material and promoting optimal pseudointimal formation.

DEVELOPMENTAL CHANGES IN THE END-SYSTOLIC PRESSURE DIAMETER RELATIONSHIP (ESPDR) IN PUPPIES

In order to evaluate the developmental changes in the ESPDR, an index of ventricular contractility independent of afterload and preload, we studied 13 normal puppies age 6 weeks to 6 months, weighing 1.7 to 21.0 kg (mean 6.8 kg). Arterial blood pressure and M-mode echocardiographic left ventricular dimensions were measured simultaneously during brief balloon occlusion of the inferior vena cava. The ESPDR using this technique was linear (r=0.95±0.02) over the range of end systolic pressure from 104.9±22.0 to 75.7±23.5 mmHg. The slope of the ESPDR (Ees) correlated significantly with the left ventricular diastolic diameter (LVD) prior to balloon occlusion, (r=-0.63 p 0.02) with Ees = -31.3 LVD + 154. The diameter intercept, Do, did not correlate with LVD (r =0.33). We conclude that Ees does decrease with normal growth and the resultant increase in LVD. This apparent change in Ees with growth may be normalized by the LVD, suggesting that left ventricular pump function and contractility does not change in puppies over the ages studied. Furthermore, studies of the ESPDR in pathological states which alter the LVD should normalize Ees for LVD to more accurately assess left ventricular contractility.