Third-time coronary artery bypass operations: surgical strategy and results.

BACKGROUND: Increasingly, patients are returning for a second, third, and even fourth coronary artery bypass graft (CABG) procedure. METHODS: This report reviews the in-hospital and long-term outcomes for 102 patients undergoing a third or fourth CABG at Emory University from December 1977 to April 1994. RESULTS: The mean interval from the first to second CABG was 5.2 +/- 3.5 years and from the second to the third CABG 6.8 +/- 4.1 years. The mean age was 6 +/- 9 years, 91% were male, 33% had hypertension, 16% diabetes, 86% class III or IV angina (Canadian Cardiovascular Society), 4.4% congestive failure (New York Heart Association), and 73% three-vessel disease. The in hospital mortality rate was 9.8%, with a perioperative myocardial infarction rate of 8.8% and a stroke rate of 1.9%. CONCLUSIONS: These perioperative mortality and myocardial infarction rates are several times higher than those reported for initial revascularizations or first-time redo CABG operations. However, the 5- and 10-year survival rates of 79% and 59%, respectively, and a myocardial infarction-free survival of 62% at 5 years, the benefits of a third-time CABG procedure are apparent for this high-risk group of patients.

Clinical significance of perioperative Q-wave myocardial infarction: the Emory Angioplasty versus Surgery Trial.

OBJECTIVE: The primary end point of the Emory Angioplasty versus Surgery Trial was a composite of three events: death, Q-wave infarction, and a new large defect on 3-year postoperative thallium scan. This study examines the clinical significance of Q-wave infarction in the surgical cohort (194 patients) of the Emory trial. METHODS: Twenty patients (10.3%) with Q-wave infarctions were identified: 13 patients had inferior Q-wave infarctions and seven patients had anterior, lateral, septal, or posterior Q-wave infarctions (termed anterior Q-wave infarctions). RESULTS: In the inferior Q-wave infarction group, postoperative cardiac catheterization (at 1 year or 3 years) in 11 patients revealed normal ejection fraction (ejection fraction >55%) in 10 (91%), no wall motion abnormalities in 10 (91%), and all grafts patent in 10 (91%). In the anterior Q-wave infarction group, postoperative catheterization in six patients revealed normal ejection fractions in five (83%), no wall motion abnormalities in three (50%), and all grafts patent in three (50%). Average peak postoperative creatine kinase MB levels were as follows: no Q-wave infarction (n = 174) 37 +/- 43 IU/L, inferior Q-wave infarction 40 +/- 27 IU/L, and anterior Q-wave infarction 58 +/- 38 IU/L. Mortality in the 20 patients with Q-wave infarctions was 5% (1/20) at 3 years; in patients without a Q-wave infarction it was 6.3% (11/174) (p = 0.64). Of 17 patients with a Q-wave infarction who underwent postoperative catheterization, 11 (65%) had a normal ejection fraction, normal wall motion, and all grafts patent with an uneventful 3-year postoperative course. CONCLUSIONS: The core laboratory screening of postoperative electrocardiograms, particularly in the case of inferior Q-wave infarctions, appears to identify a number of patients as having a Q-wave infarction with minimal clinical significance. Q-wave infarction identified in the postoperative period seems to be a weak end point with little prognostic significance and therefore not valuable for future randomized trials.

Prevention of postoperative pericardial adhesions with a hyaluronic acid coating solution. Experimental safety and efficacy studies.

Postoperative pericardial adhesions complicate reoperative cardiac procedures. Topical application of solutions containing hyaluronic acid have been shown to reduce adhesions after abdominal and orthopedic surgery. The mechanism by which hyaluronic acid solutions prevent adhesion formation is unknown but may be due to a cytoprotective effect on mesothelial surfaces, which would limit intraoperative injury. In this study, we tested the efficacy and safety of hyaluronic acid coating solutions for the prevention of postoperative intrapericardial adhesion formation. Eighteen mongrel dogs underwent median sternotomy and pericardiotomy followed by a standardized 2-hour protocol of forced warm air desiccation and abrasion of the pericardial and epicardial surfaces. Group 1 (n = 6) served as untreated control animals. Group 2 (n = 6) received topical administration of 0.4% hyaluronic acid in phosphate-buffered saline solution at the time of pericardiotomy, at 20-minute intervals during the desiccation/abrasion protocol, and at pericardial closure. The total test dose was less than 1% of the circulating blood volume. Group 3 (n = 6) served as a vehicle control, receiving phosphate-buffered saline solution as a topical agent in a fashion identical to that used in group 2. At resternotomy 8 weeks after the initial operation, the intrapericardial adhesions were graded on a 0 to 4 severity scale at seven different areas covering the ventricular, atrial, and great vessel surfaces. In both the untreated control (group 1, mean score 3.2 +/- 0.4) and vehicle control (group 3, mean score 3.3 +/- 0.2) animals, dense adhesions were encountered. In contrast, animals treated with the hyaluronic acid solution (group 2, mean score 0.8 +/- 0.3) characteristically had no adhesions or filmy, transparent adhesions graded significantly less severe than either the untreated control (group 2 versus group 1, p < 0.001) or vehicle control (group 2 versus group 3, p < 0.001) animals. In separate experiments, six baboons were infused with 0.4% hyaluronic acid in phosphate-buffered saline solution in volumes equivalent to 2.5%, 5%, and 10% of the measured circulating blood volume. The 2.5% and 5% infusions had no effect on the parameters measured; infusion of the 10% volume produced transient hemodynamic, coagulation, and gas exchange abnormalities. Hyaluronic acid solutions are efficacious in the prevention of pericardial adhesions in this model, and they appear safe in doses five times the amount needed to prevent adhesions. Further studies investigating the mechanism by which these solutions prevent adhesions, their optimal dose and method of application, and documentation of their safe use in humans are warranted.

Acute effects of massive transfusion of a bovine hemoglobin blood substitute in a canine model of hemorrhagic shock.

The capability of stroma-free hemoglobin solutions to act as a plasma expander with oxygen and carbon dioxide transport properties has encouraged the idea of their possible use in settings of massive blood loss. Using a canine hemorrhagic shock model (systolic arterial pressure < or = 50 torr for 60 min), we evaluated the efficacy of an ultra-pure stroma-free bovine hemoglobin solution (PBHg) as a resuscitation fluid in hypovolemic and acidotic animals, using homologous blood (PRBC) and 10% human serum albumin (HSA) as control solutions. Following volume replacement, dogs were studied for 2 h under anesthesia and for 4 h subsequently while awake. Resuscitation with PBHg (30 +/- 3 ml/kg) was able to restore stable hemodynamics and correct acidosis to an extent comparable to that in animals treated with PRBC. Additionally, oxygen transport was maintained at a higher level than that in dogs treated with HSA. Administration of PBHg in this shock model revealed no significant cardiopulmonary toxicity or adverse effects. These short-term results suggest that PBHg may be useful for effective resuscitation after major blood loss.

Determinants of maximal right ventricular function.

After heart transplantation, right ventricular failure can occur because of increased afterload. Previous studies have suggested that the maximal pressure the right ventricle can develop is determined primarily by right ventricular perfusion pressure. However, the interaction of the left ventricle and the pericardium as functional co-determinants of maximal right ventricular function is unknown. This study was undertaken to determine the interaction of the pericardium, left ventricular pressure, and right coronary artery perfusion pressure as potential determinants of maximal right ventricular function. In an acute canine preparation, with progressive pulmonary artery constriction, maximal generated right ventricular pressure was determined over a range of left ventricular systolic pressures. Additional groups of dogs were studied with the right coronary artery cannulated and were maintained at constant perfusion pressure. In all preparations, the maximal pressure the right ventricle could generate was linearly related to left ventricular systolic pressure. Having a closed pericardium markedly enhanced this effect; some effect was present with an open pericardium, although the magnitude of the influence of left ventricular pressure on maximal right ventricular pressure was much less. Maintaining constancy of right coronary artery perfusion pressure, either at high or low values, did not alter these findings nor did it alter the influence of the pericardium. These results suggest that right ventricular perfusion may not be the sole determinant of maximal right ventricular function. Furthermore, with the pericardium open, such as in the posttransplantation state, the left ventricular contribution to maximal right ventricular function may be diminished, increasing vulnerability for right ventricular failure caused by increased afterload.

Ultra-pure polymerized bovine hemoglobin blood substitute: effects on the coronary circulation.

The effects of stroma-free hemoglobin (SFHgb) on the coronary circulation remain unclear. An intact canine model utilizing intracoronary adenosine to abolish the confounding effect of autoregulation was used to study maximal myocardial oxygen delivery during progressive hemodilution with polymerized bovine SFHgb. The circumflex coronary artery was instrumented with a flow probe, hydraulic constrictor, and proximal and distal catheters for adenosine infusion and distal pressure measurement, respectively. This preparation was used to generate diastolic coronary pressure-flow relations during maximal vasodilation. Maximal coronary conductance and maximal myocardial oxygen delivery were determined in two groups of 7 dogs each following hemodilution, first with 6% hetastarch (Control), followed by further hemodilution with ultra-pure, polymerized, bovine SFHgb. After hemodilution with SFHgb, maximal coronary flow increased slightly without evidence of coronary vasoconstriction. Since hemodilution with this material increases oxygen carrying capacity, maximal oxygen delivery is greater than Control, despite the very low canine hematocrit. These findings suggest: 1) SFHgb can provide adequate oxygen delivery to the myocardium despite extreme degrees of hemodilution, and 2) in this intact model, there is no evidence of adverse coronary vasomotion.

The silent brain infarct in carotid surgery.

The destructive potential of carotid artery disease is underestimated by the clinical classification that surveys only that part of the brain with clear somatic representation. Asymptomatic patients are found to have brain infarctions on CT scan for which there is no history or symptom. To assume "benign" behavior of a carotid lesion, a patient must be both asymptomatic and "asignomatic." Likewise, when the morbidity of carotid operations is reported, silent infarcts must somehow be taken into account. We investigated this "silent" disease in a prospective study of 100 carotid operations done on 91 patients over a 9-month period in our service. All patients had arch and four-vessel selective arteriography. Detailed neurologic examinations and CT scans were done before and after surgery. Of the 91 patients, 78 (86%) had a history of neurologic problems. Preoperative CT scans showed infarction in 21 patients, but only 57% of the infarctions correlated with symptoms and/or history. Among patients with a history of transient ischemic attack (TIA), 19% had an infarction seen on CT scan; however, among those patients who had lateralizing TIAs, the incidence of unsuspected infarction was higher (26%). Arteriography showed a lesion in all carotid systems supplying a symptomatic or infarcted hemisphere. Following 100 operations, four patients had neurologic abnormalities--two had transient hemianopsia and two had hemiparesis. CT scan showed a new infarct in all four patients as well as in eight other patients without neurologic findings; two of these silent postoperative infarctions were found in the hemisphere opposite the side of the operated carotid artery.(ABSTRACT TRUNCATED AT 250 WORDS)