Graft patency in patients with coronary artery bypass operation complicated by perioperative myocardial infarction.

Coronary artery bypass graft patency was examined by contrast-enhanced computed tomography in 18 patients with perioperative myocardial infarction soon after surgery to determine the role of graft occlusion. Preoperative coronary angiograms were reviewed to assess native coronary disease and visible collateral channels in the distribution of the myocardial infarction. Perioperative myocardial infarction was diagnosed if creatine kinase-MB was elevated, characteristic electrocardiographic changes occurred and, in the majority of cases, the pyrophosphate scan was positive. Fourteen patients (78%) had patent grafts and perioperative myocardial infarction in the distribution of the grafted vessel. Four patients had an occluded graft with infarction in the distribution of the grafted vessel. Among the 14 patients with patent grafts, there was a significant difference (p less than 0.0005) in the degree of the mean (+/- standard deviation) diameter stenosis of 80 +/- 11% in native coronary vessels supplying the perioperatively infarcted myocardium versus a 55 +/- 12% mean diameter stenosis in the 23 bypassed native coronary vessels supplying noninfarcted myocardium. It is concluded that the majority of perioperative myocardial infarcts associated with coronary artery bypass operations are not caused by graft occlusion. The severity of coronary obstruction in the grafted vessel and the lack of collateral vessels to the region of perioperative infarction in patients with patent grafts suggests that an island of jeopardized myocardium exists that is subject to inadequate intraoperative preservation.

Evaluation of early postoperative coronary artery bypass graft patency by contrast-enhanced computed tomography.

Fifty patients with 117 coronary bypass grafts were studied by contrast-enhanced computed tomography at an average of 5 +/- 4 days after surgery to determine if this technique was a feasible method for detecting early postoperative graft occlusion. The study was limited in only three patients because of incisional chest pain (one patient) or multiple metal clips attached to the graft (two patients). The distal patency of sequential grafts cannot be determined by current techniques. There was a lower graft patency rate (70%) in the 10 patients with perioperative myocardial infarction than in the 40 (95%) without (p less than 0.025), but most regions of infarcted myocardium were perfused by patent grafts. There were eight graft occlusions in eight patients. The graft occlusion rate (30%) was significantly higher (p less than 0.025) in grafts with intraoperative flows less than 45 ml/min. The postoperative complications of myocardial dysfunction, arrhythmia and coronary artery spasm did not correlate with graft occlusion. Early graft occlusion is uncommon (7%) and usually occurs in grafts with low flows or severe distal disease (seven of eight grafts), or both. Thus, the need for early reoperation is very infrequent. It is concluded that contrast-enhanced computed tomography is feasible for the assessment of coronary bypass graft patency. Because early graft occlusion is unusual the technique may be an ideal noninvasive screening method.

Effect of managed care on cardiovascular specialists: involvement, attitudes and practice adaptations.

OBJECTIVES: This study was undertaken to determine the extent to which cardiovascular specialists are involved with and affected by managed care and to ascertain their attitudes toward it. This survey also served as the follow-up to an initial study on the subject performed by the American College of Cardiology in 1993. BACKGROUND: The initial 1993 study was performed to address the lack of any comprehensive examination of the impact of managed care on cardiovascular specialists. In 1995, to reexplore this question and follow up the 1993 findings, the College conducted a survey of its membership in the following areas: 1) physician relationship with managed care plans; 2) number of managed care contracts; 3) breakdown of revenue by payment source; 4) changes in practice in response to managed care; and 5) physician attitudes toward managed care. To the extent feasible, the 1995 questionnaire paralleled the 1993 instrument to facilitate comparisons. METHODS: A questionnaire was mailed to 5,147 practicing College members in the United States, who were categorized by specialty as pediatric cardiologists, adult cardiologists or cardiovascular surgeons. Mailings were sent to 1) all pediatric cardiologists and cardiovascular surgeons; 2) randomly selected adult cardiologists practicing in 10 states with high managed care penetration; and 3) randomly selected adult cardiologists in the nine U.S. census areas who were not practicing in the 10 states with high managed care penetration. RESULTS: Usable surveys were returned by 1,236 respondents, for an overall response rate of 24%. Involvement with at least one type of managed care organization was reported by 89% of respondents, up from 76% in 1993. Although managed care relationships had increased across physician age, region, practice and specialty, respondents indicated that, on average, well below 50% of their practice revenues stem from managed care contracts. To adapt to the managed care environment, strategic practice changes, such as joining a cardiovascular network, implementing continuous quality improvement systems and adopting clinical pathways, were being instituted by most respondent practices of nine or more physicians. Smaller groups were less active. Most respondents involved with managed care disliked its effects, particularly in clinical matters. Their attitudes toward the assumption of risk, managed fee-for-service arrangements and a private versus single-payer system show that there is no uniformity of opinion regarding the best means to contain costs and promote efficiency. CONCLUSIONS: Managed care has become an established part of cardiovascular specialist practice in the United States. Although this trend is viewed with some disfavor, most respondents are making practice changes to adapt to this new environment.

Reparative approach for right-sided endocarditis. Operative considerations and results of valvuloplasty.

From 1981 to 1986, 12 patients were operated on for right-sided endocarditis after the failure of initial medical treatment (five staphylococcal, three streptococcal, two fungal, one gram-negative, and one mixed organism). The sources of infection were intravenous drugs in six patients, central catheters in two, and malformations in four. Preoperatively, 10 of 12 (83%) of these patients were in class III or IV. Reparative or reconstructive approaches, including valvuloplasty, were attempted for all these right-sided endocarditis lesions and were hemodynamically effective in 10 of 12 (83%) patients. The low right-sided intracardiac pressures and the three-leaflet configuration (one pulmonary and nine tricuspid valves) have lent themselves to this approach. Extensive annular invasion and multileaflet infections were technical limitations in the remaining patients. The overall outcome was favorable during the mean follow-up period of 25 months (hospital mortality 1/12, 8.3%; late death 1/11, 9%). Reparative or reconstructive approaches for right-sided infective endocarditis should be considered and can be successfully achieved. Their advantages include (1) improved hemodynamics, (2) low recurrence, and (3) favorable long-term results without staged or simultaneous prosthetic valve replacement.

Systemic hypertension following myocardial revascularization. A method of treatment using epidural anesthesia.

Seven of 12 patients (58%) undergoing myocardial revascularization surgery became hypertensive in the immediate postoperative period. The hypertensive patients had significant elevations in peripheral vascular resistance (22.0 +/- 2.0 S.E. resistance units) compared to measurements in normotensive patients (15.6 +/- 1.3 S.E. resistance units) (p less than 0.05), whereas the heart rates and cardiac indices were similar. Administration of thoracic epidural anesthesia to postoperatively hypertensive patients lowered systemic arterial pressure by decreasing peripheral vascular resistance (p less than 0.005) but not affecting the pulse rate and cardiac index. The ratio diastolic pressure-time index/systemic pressure-time index (DPTI/SPTI), an indirect measurement of subendocardial oxygenation, increased from preanesthetic values of 0.80 +/- 0.08 S.E. to 1.09 +/- 0.09 S.E. (p less than 0.025) after the systemic arterial pressure was lowered in postoperatively hypertensive patients. Hypertensive episodes following myocardial revascularization procedures appear related to increased alpha-adrenergic activity, which products elevation in peripheral vascular resistance. Decreasing peripheral vascular resistance by chemical sympathectomy with thoracic epidural anesthesia lowers the systemic arterial pressure and improves the DPTI/SPTI ratio.

Improved survival after coronary artery surgery in patients with extensive coronary artery disease.

Survival in patients with ischemic heart disease is closely related to the extent of coronary artery obstruction as determined angiographically. One hundred forty-nine consecutive patients underwent coronary artery bypass surgery from November, 1971, to October, 1974. There were 2 late cardiac deaths, 1 late noncardiac death, and 1 hospital death, an operative mortality rate of 0.7 per cent and a total mortality rate of 2.7 per cent. Coronary angiograms were scored according to the method of Friesinger, Page, and Ross. Fifty-four per cent (80/149) had scores of 10 or greater. Cumulative survival was analyzed according to life-table techniques; in the 80 surgically managed patients with scores of 10 or greater, survival at 3 years was 98 per cent. Friesinger's 47 nonoperated patients with similar angiographic scores had a 3 year cumulative survival of 68 per cent. Although this study compares different groups, the surgical series was composed of older patients (mean age 52 as compared to 44 years), includes 22 patients operated on urgently for preinfarction angina pectoris, and includes 18 patients with abnormal ventricular function. These data suggest that coronary artery bypass surgery can favorably influence prognosis in patients with severe coronary artery disease.

Management of symptomatic tetralogy of Fallot in the first year of life.

The surgical management of symptomatic tetralogy of Fallot in infants is debatable. The question of total correction versus palliation and the type of palliative procedure remain controversial. During the past 4 years, 30 infants, aged 1 day to 12 months (mean 5.6 months) with symptomatic tetralogy of Fallot underwent either total correction (21 infants) or palliation by relieving the pulmonary stenosis with a right ventricular outflow tract patch (nine infants). The ratio of diameter of the right pulmonary artery to diameter of the ascending aorta (PA/Ao ratio) was calculated from the anteroposterior cineangiogram of all patients. There were three operative deaths in the total correction group; two of these occurred in infants with PA/Ao ratios less than 0.3. One death occurred in the 19 patients undergoing total correction with PA/Ao ratios greater than 0.3 (mortality rate 5.3%). All nine infants undergoing right ventricular outflow tract patching had PA/Ao ratios less than 0.3, and one operative death occurred in this group. Four patients who had right ventricular outflow tract patching have had repeat cardiac catheterization 2 to 15 months postoperatively. All four have shown symmetrical enlargement of the pulmonary arterial tree and significant increases in their PA/Ao ratios.

Left ventricular outflow enlargement by the Konno procedure.

The optimal management of patients with small aortic anulus or left ventricular outflow tract obstruction remains unclear. Between 1976 and March, 1982; 18 patients have undergone enlargement of their left ventricular outflow tract by means of the Konno or a modification of the Konno procedure. Fourteen of these 18 patients had previous operations for aortic stenosis or tunnel left ventricular outflow tract, and two patients had undergone three previous operations. All 18 patients had symptoms of either heart failure of chest pain, or had electrocardiographic evidence of strain. They ranged in age from 4 years to 58 years, with 13 of the 18 patients being less than 20 years of age. A Dacron patch was used to enlarge the left ventricular outflow tract after incising down the ventricular septum. In all patients, at least a 21 mm valve could be placed, with between 50% and 65% of the valve anulus being made up of natural tissue. The remaining portion of the valve anulus was constructed from the Dacron patch. The patch was extended up to enlarge the ascending aorta, and a pericardial patch was used to close the defect in the right ventricular outflow tract. In all 18 patients the gradient was obliterated at the time of operation. There was one early death in a patient who had previous insertion of a left ventricular apical-aortic conduit in which the heterograft valve had degenerated. There has been one late death because of bacterial endocarditis in a child who also had a parachute mitral valve and evidence of pulmonary hypertension. The remaining 16 patients are functioning well after the Konno procedure. Three are receiving warfarin sodium, and 13 are receiving aspirin. These results suggest that this is an acceptable method of treating patients with small aortic anulus or left ventricular outflow tract obstructions and would appear to have advantages over a left ventricular apical-aortic conduit.

The impact of coronary artery bypass on late myocardial infarction.

Two hundred consecutive patients undergoing coronary artery bypass for stable and unstable angina pectoris were followed clinically 3 to 53 months (mean 27) and with serial electrocardiograms (ECG's) 3 to 43 months (mean 18.5) postoperatively. Complete (twelve lead) resting ECG data including preoperative, early postoperative (in hospital), and late (post hospital) studies were available in 98 per cent (196/199) of hospital survivors. A total of 2,304 ECG's were examined by two cardiologists for a total follow-up of 3,629 patient months. Myocardial infarction was defined as the appearance of a new, significant (Minnesota Code) Q wave. Fifty-four per cent (108/200) had triple vessel disease and 24 per cent (47/200) preinfarction angina pectoris by strict criteria. There was one hospital death for an operative mortality of 0.5 per cent (1/200). There was one late fatal and three late nonfatal myocardial infarctions. Seventeen patients developed new Q waves in the early postoperative period, a perioperative infarction rate of 8.5 per cent (17/200). The 43 month cumulative myocardial infarction rate, including all early and late postoperative new Q waves and three late deaths from cardiac disease, was 14 per cent. Twenty-two per cent (20/91) showed disappearance of Q waves present at the time of hospital discharge. These data suggest that the late myocardial infarction rate is low in surgically managed patients.

Myocardial protection with cold, ischemic, potassium-induced cardioplegia.

A total of 204 patients, ages 3 months to 84 years, underwent open-heart surgery with the aid of cardiopulmonary bypass with moderate hypothermia. For protection of the myocardium, cardioplegia was induced by washing out the coronary arteries with an iced, buffered, isoosmolar, potassium-based infusate. After aortic cross-clamping, the aortic root or individual coronary arteries were perfused with 500 to 2,000 c.c. of an aqueous solution (at zero to 4 degrees C.) containing 20 mEq. of potassium. Periods of ischemic arrest as long as 208 minutes have been well tolerated, with only two of the eleven hospital deaths considered heart related. Defibrillation occurred spontaneously in 41 per cent and after one shock in 47 per cent of patient, without apparent correlation between duration of ischemia and restoration of effective rhythm.

Halothane and morphine-nitrous oxide anesthesia in patients undergoing coronary artery bypass operation. Patterns of intraoperative ischemia.

To examine whether the hemodynamic responses to halothane or morphine-nitrous oxide anesthesia produce different patterns of myocardial ischemia in patients undergoing myocardial revascularization, we studied 26 patients anesthetized with nitrous oxide (50%) and either halothane (0.2% to 1.0% end-tidal concentration) or morphine (2 mg/kg, given intravenously). We measured systemic and coronary hemodynamics and took blood samples to measure blood gases, oxygen content, and lactate and norepinephrine concentrations. Systemic blood pressure, rate-pressure produce, systemic vascular resistance, cardiac output, and stroke work were elevated following sternotomy in patients anesthetized with morphine, whereas halothane obtunded these hemodynamic responses to surgical stress. Intraoperative myocardial ischemia occurred in both patient groups. Ten of 14 patients receiving halothane and eight of 12 receiving morphine had at least one episode of either ST-segment depression or myocardial lactate production. The difference between these groups was not statistically significant. Only patients anesthetized with morphine had a significantly elevated rate-pressure product when ischemia occurred. In this selected series of patients subjected to myocardial revascularization, two sustained a myocardial infarction and four died in the postoperative period. The incidence of these and other indices of postoperative morbidity was not related to choice of primary anesthetic and did not differ between the patients who sustained ischemia and those who did not.

Assessment of saphenous vein graft patency by contrast-enhanced computed tomography.

Early saphenous vein coronary bypass graft patency has been found to range from 82% to 94%. Recent advances in computed tomography have led to the development of a safe, effective, and "relatively noninvasive" means of assessing early graft patency. We designed a prospective study using contrast-enhanced computed tomography (CECT), postulating that selected grafts might be redone prior to the development of pericardial adhesions if early closure was demonstrated. Forty-three random patients undergoing elective coronary artery bypass comprise the study group. All patients underwent CECT study of graft patency an average of 6 days postoperatively (range 1 to 17 days). Ninety of 96 grafts were open, for an early patency rate of 94%. Three of the grafts were closed because of poor run-off or extensive distal coronary atherosclerosis. Two additional grafts were closed, one in a patient with severe atherosclerosis of the ascending aorta and one in a patient having triple vessel bypass using cephalic vein because of limited conduit material. Only one graft was closed without apparent cause and judged potentially suitable for reoperation. CECT was found to be a safe and potentially useful means of assessing early graft patency, particularly in patients sustaining untoward clinical events.

Repair of dissection of the thoracic aorta. Evaluation of false lumen utilizing computed tomography.

During the period 1975 to 1980, 21 patients with thoracic aortic dissections underwent surgical treatment. The operative technique was resection and tube graft replacement of the segment of the aorta containing the entry point into the false channel. Eleven Type A and 10 Type B dissections were resected. The hospital survival rate was 95%. The single operative death occurred in a patient with an acute Type A dissection. Three patients had total resection of the dissected segment; three had clotted false lumina; five had distal anastomosis to true and false lamina; and 10 had distal anastomosis to the true lumen only, with proximal entry into the false lumen obliterated by incorporating both intimal and adventitial walls in a single suture line. The late survival rate was 95% (mean 32 months, range 8 to 63 months). No late ruptures occurred. Computed tomography (CT) with contrast enhancement was used to evaluate the aorta and any residual false lumen at follow-up. Seven of eight patients in whom obliteration was attempted and CT scans performed demonstrated persistence of false lumen perfusion; in six of the eight, preoperative angiograms were adequate for evaluation of false lumen runoff. Major vessels arose from the false lumen in all cases, except in the one patient in whom obliteration was later successful. This report demonstrates that there is persistence of false lumen perfusion in patients in whom obliteration is attempted, and the mechanism of this persistence is the presence of major vessel runoff. It suggests that the mechanism by which long-term survival is achieved is by resection of the segment of aorta containing the entry site, which is frequently the site of subsequent enlargement and rupture, rather than obliteration of the false channel.

Current controversies in the conduct of the coronary bypass operation.

Recent reports comparing medical versus surgical management of patients with ischemic heart disease highlight the importance of technical quality in the interpretation of surgical results. This review is an attempt to examine current controversies in the conduct of coronary artery bypass with the purpose of suggesting strengths and weaknesses of alternative approaches. Topics include cold cardioplegia versus intermittent aortic occlusion, left ventricular venting, anastomotic technique, optical magnification, "complete vascularization," sequential versus individual grafting, internal mammary artery versus saphenous vein as conduits and the choice of alternative conduits when saphenous vein is unavailable.