Clinical experience in coronary bypass surgery for abciximab-treated patients.

Abciximab effectively inhibits platelet aggregation and, therefore, there is considerable concern regarding bleeding complications in patients who require coronary artery bypass graft (CABG) surgery while affected by the drug. This presentation reviews the available published literature regarding CABG in abciximab-treated patients, the clinical results of emergency CABG in 12 patients, and management suggestions for the abciximab-treated patient requiring emergency surgery.

Emergency coronary artery bypass graft surgery in abciximab-treated patients.

BACKGROUND: Although the platelet antiaggregant abciximab is frequently used with percutaneous coronary interventions, results of emergency coronary artery bypass graft operations in patients recently treated with abciximab are poorly characterized. METHODS: During a 29-month period, 12 patients required emergency coronary artery bypass grafting within 12 hours (mean, 1.9 hours) of abciximab therapy. Our full standard heparin dose regimen was used (mean heparin dose, 53,000 U per patient). Each patient received a single platelet transfusion dose after protamine administration, and further blood products were transfused as necessary. Clinical outcome and transfusion requirements were compared with predicted results based on risk-adjusted historical patients. RESULTS: No patients died and none were returned to the operating room for coagulopathy-related bleeding. Per patient transfusion requirements were as follows: red blood cells, 3.6 units; apheresis platelets, 1.4 units; and fresh frozen plasma, 1.5 units. As compared with predicted values, there was no excessive incidence of mortality, stroke, or red blood cell transfusion requirements. CONCLUSIONS: Emergency coronary artery bypass graft operations using full-dose heparin can be performed successfully in acutely ischemic abciximab-treated patients. Prophylactic transfusion of platelets after protamine administration appears to be useful.

Aprotinin for primary coronary artery bypass grafting: a multicenter trial of three dose regimens.

BACKGROUND: High-dose aprotinin reduces transfusion requirements in patients undergoing coronary artery bypass grafting, but the safety and effectiveness of smaller doses is unclear. Furthermore, patient selection criteria for optimal use of the drug are not well defined. METHODS: Seven hundred and four first-time coronary artery bypass grafting patients were randomized to receive one of three doses of aprotinin (high, low, and pump-prime-only) or placebo. The patients were stratified as to risk of excessive bleeding. RESULTS: All three aprotinin doses were highly effective in reducing bleeding and transfusion requirements. Consistent efficacy was not, however, demonstrated in the subgroup of patients at low risk for bleeding. There were no differences in mortality or the incidences of renal failure, strokes, or definite myocardial infarctions between the groups, although the pump-prime-only dose was associated with a small increase in definite, probable, or possible myocardial infarctions (p = 0.045). CONCLUSIONS: Low-dose and pump-prime-only aprotinin regimens provide reductions in bleeding and transfusion requirements that are similar to those of high-dose regimens. Although safe, aprotinin is not routinely indicated for the first-time coronary artery bypass grafting patient who is at low risk for postoperative bleeding. The pump-prime-only dose is not currently recommended because of a possible association with more frequent myocardial infarctions.

Aprotinin for coronary artery bypass grafting: effect on postoperative renal function.

Two hundred sixteen patients undergoing coronary artery bypass graft procedures were randomized to receive either high-dose aprotinin or placebo. Clinically important postoperative renal insufficiency was infrequent, with a single patient (0.9%) from each group requiring dialysis. Although increases in the serum creatinine level occurred postoperatively in more patients who received aprotinin (20/108) than in those given placebo (13/108), the difference between the two groups was not statistically significant (p = 0.186), and the increases were generally small and transient. Likewise, there was no difference between the groups in terms of the incidence of abnormal serum electrolyte levels, blood urea nitrogen levels, or urinalysis findings, or in the frequency of abnormal creatinine clearance rates. Under the conditions described, aprotinin use does not appear to be associated with a significant risk of serious renal toxicity.

Early changes in defibrillation threshold following implantation of a nonthoracotomy system in dogs.

BACKGROUND: Nonthoracotomy systems are rapidly becoming the preferred surgical method for implantation of cardioverter defibrillators. Testing is performed at the time of implantation to insure an adequate margin of safety for defibrillation. However, this safety margin may change with lead maturation. This study evaluated changes in defibrillation threshold following implantation of a nonthoracotomy system. METHODS AND RESULTS: Ten dogs underwent implantation of a nonthoracotomy system consisting of a single catheter with a distal coil electrode in the right ventricular apex and a proximal coil electrode in the superior vena cava forming a common anode with a subcutaneous patch over the left thorax. Defibrillation threshold testing, using a biphasic waveform, was performed on each animal under general anesthesia at implantation (day 1) and subsequently on postoperative days 3, 7, 10, 17, 24, 31, 38, and 45. E50, the energy associated with a 50% likelihood of successful defibrillation, was determined at each setting. The mean E50 was 12.2 +/- 1.1 J at the time of implantation, increasing 36% to 16.8 +/- 2.0 J by day 38 (P < 0.01). Individual increases in E50 of 10-12 J were observed in four animals. CONCLUSIONS: Energy requirements for defibrillation with a nonthoracotomy system increase during the early postoperative period, with the highest defibrillation threshold observed at 38 days. This increase may be applicable to humans and should be considered when selecting an adequate energy safety margin for defibrillation at time of implantation.

Aprotinin for coronary bypass operations: efficacy, safety, and influence on early saphenous vein graft patency. A multicenter, randomized, double-blind, placebo-controlled study.

The purpose of this study was to evaluate the efficacy and safety of aprotinin in a U.S. population of patients undergoing coronary artery bypass grafting. Early vein graft patency rates were assessed by ultrafast computed tomography. A total of 216 patients at five centers were randomized to receive either high-dose aprotinin or placebo during the operation; 151 patients underwent primary operation, and 65 underwent repeat procedures. Total blood product exposures in the primary group were 2.2 per patient receiving aprotinin as compared with 5.7 per patient receiving placebo (p = 0.010). The repeat group had 0.3 exposures per patient receiving aprotinin as compared with 10.7 per patient receiving placebo (p = < 0.001). Consistent reductions in the percent of patients requiring donor red blood cells and in the number of units of platelets, fresh frozen plasma, and cryoprecipitate required were associated with the use of aprotinin in both primary and repeat groups. Mortality was 5.6% in the aprotinin group and 3.7% in the placebo group (p = 0.517). In the primary group, clinical diagnoses of myocardial infarction were made in 8.9% of patients receiving aprotinin as compared with 5.6% of the patients receiving placebo (p = 0.435). In the repeat group, infarctions occurred in 10.3% of patients receiving aprotinin and 8.3% of patients receiving placebo (p = 1.000). Secondary analysis of electrocardiograms and available enzyme data showed no significant difference in infarction rates between the treatment groups. There was no difference in clinically significant renal dysfunction. The early vein graft patency rates were 92.0% in the aprotinin group and 95.1% in the placebo group (p = 0.248). In this study, aprotinin was effective in reducing bleeding and blood product transfusion rates, and its use was not associated with an increase in complications. An adverse effect on early vein graft patency rates was not demonstrated, but the number of grafts assessed was insufficient for absolute conclusions in this regard.

Aortic valve replacement with pulmonary or aortic allografts.

Limited availability of aortic valve allografts suggests consideration of pulmonary valve allografts for aortic valve replacement (AVR). From 1987 through 1990, 20 patients underwent AVR with cryopreserved aortic allografts (group 1). Five patients underwent AVR with pulmonary allografts (group 2) because no aortic allografts of the appropriate size were available. Indications for AVR in group 1 were endocarditis in five patients, aortic insufficiency in six, and aortic stenosis in nine. Indications for AVR in group 2 were endocarditis in two patients and aortic insufficiency in three. In group 1 there was one operative death and two late deaths resulting from noncardiac causes. There were no operative or late deaths in group 2. Follow-up was complete (group 1: 1-32 months [mean, 14 months]; group 2: 1-24 months [mean, 13 months]). All surviving patients remain in New York Heart Association (NYHA) class I or II. Postoperative catheterization was performed in 21 of 24 surviving patients. All patients have been followed since hospitalization with serial studies that included computerized cine tomography of the chest and echocardiograms. No false aneurysms, stenoses, or clinically significant regurgitation have occurred, although one patient in group 2 showed 2+ insufficiency at catheterization. One group 1 patient required repeat AVR for recurrent endocarditis. There were no reoperations in group 2. Although longer-term follow-up with larger numbers of patients is necessary, it seems that operative and early postoperative results for AVR have been similar with aortic and pulmonary valve allografts. In selected patients AVR with pulmonary allografts may be appropriate to consider when properly sized aortic allografts are unavailable.

Surgical cure of cardiac arrhythmia. 1969.

The first surgical procedure undertaken for the intended purpose of curing a patient with recurrent tachycardia was performed by Sealy in 1968, and the report of that operation was published in The Annals of Thoracic Surgery in 1969. The first attempted accessory bundle ablation was successful, marked the beginning of cardiac arrhythmia surgery, and has set the standard against which other methods of arrhythmia control must be measured.

Comparison of allografts and prosthetic valves when used for emergency aortic valve replacement for active infective endocarditis.

Aortic valve replacement (AVR) using allografts is an established method of treating aortic valve disease. It is uncertain, however, whether the increased technical demands of allograft AVR can be justified in emergency operations. This study reports 15 patients treated between 1987 and 1990 for acute bacterial or fungal endocarditis involving the aortic valve. Patients underwent emergency AVR because of severe congestive failure, overwhelming sepsis or cerebral emboli. Eight patients received prosthetic valves (group I: 4 mechanical, 4 porcine) and 7 received human allografts (group II: 5 aortic and 2 pulmonary). The groups were comparable in age (group I, 55 years; group II, 51 years), intravenous drug abuse (group I, 1; group II, 3), and previous AVR (group I, 3; group II, 2). One group I and 4 group II patients had septal abscesses. Additional procedures in group I included mitral valve replacement (2), tricuspid valve replacement (1) and aortic root replacement (1). Additional procedures in group II were mitral valve repair (1), root replacement (1), atrial septal defect closure (1) and aortocoronary bypass (1). Mean bypass times (group I, 189 minutes; group II, 204 minutes) and cross-clamp times (group I; 108 minutes; group II, 121 minutes) were similar. Operative deaths occurred in 4 of 8 group I and 1 of 7 group II patients. All surviving patients have been successfully followed (group I, 28 months; group II, 18 months). No group I patient has required reoperation. One group II patients required reoperation for recurrent infection affecting the allograft, and another group II patient died 10 months postoperatively from noncardiac causes.(ABSTRACT TRUNCATED AT 250 WORDS)

Pericardial influence on internal defibrillation energy requirements.

There is no consensus regarding optimal positioning of patch leads for implantation of automatic implantable cardioverter defibrillators. We compared the energy (in joules) required for 50% and 80% successful termination of ventricular fibrillation with titanium-mesh patch leads outside intact normal pericardium and directly on the epicardium in 13 open-chest dogs. Talc was then instilled into the pericardial space to stimulate adhesion formation and pericardial thickening. After 3 weeks of recovery, thoracotomy and defibrillation testing were repeated in nine dogs with the patch leads outside the thickened, adherent pericardium. There were no significant differences in defibrillation energy requirements between locations (p greater than 0.10). In addition, a comparison of electrical impedance measurements at 10 joules showed no significant differences (p greater than 0.30). In this animal model, defibrillation energy requirements were not altered by positioning the patch leads outside normal intact pericardium rather than placing them directly on the epicardium. Furthermore, thickened, adherent pericardium interposed between the patch leads and the heart does not increase defibrillation energy requirements. These data suggest that placement of automatic implantable cardioverter defibrillator patch leads outside the pericardium in patients (including those with pericardial adhesions from previous cardiac operations) will not adversely affect defibrillation efficacy and thus can simplify the implantation procedure.

Surgical treatment of cardiac myxomas: long-term results.

Between 1965 and 1988, 22 patients underwent 24 operations for cardiac myxomas. Two patients had the complex myxoma syndrome. Mitral valve replacement was required at initial operation in 2 patients. One patient died perioperatively, and 5 others died subsequently. The 16 surviving patients recently underwent evaluation at a mean duration of 9 years after operation. Ten are asymptomatic and 6 have New York Heart Association class II symptoms. Nine patients continue to be employed. Eleven are in sinus rhythm, 3 have permanent pacemakers, and 2 have chronic atrial arrhythmias. Echocardiography showed atrioventricular valve insufficiency in 3 patients and reduced contractility in 4, but no new tumor recurrences. The long-term prognosis of this relatively large group of patients with cardiac myxomas has been good. Patients without the complex myxoma syndrome had no recurrence, whereas 2 patients did require reoperation for mitral valve replacement. Long-term disability and chronic arrhythmias have been infrequent, and functional status and employability of these patients have been very good.

Clinical outcome of emergency repeat coronary artery bypass surgery.

To determine the clinical outcome of patients requiring emergency repeat coronary artery bypass graft (CABG) procedures, we reviewed 23 such procedures performed for ongoing myocardial ischemia refractory to medical management. The operative mortality was 17%. On follow-up, an average of 24.9 months after emergency reoperation, 14 of the 19 survivors (74%) had recurrent angina. As compared to a randomly selected group of 25 patients who underwent elective repeat CABG procedures during the same time period, the incidence of late cardiac events was significantly higher (79% in the emergency group, 30% in the elective surgery group) and fewer patients had received internal mammary artery (IMA) grafts (9% vs 52%). Emergency repeat CABG operations have considerable operative mortality and poor postoperative functional results with the majority of survivors developing recurrent ischemic syndromes within a short period of time.

Limited lateral thoracotomy. Improved postoperative pulmonary function.

A prospective randomized controlled study was designed to determine differences in early postoperative pulmonary function, pain, and complications between patients undergoing limited lateral muscle-sparing thoracotomy. Fifteen patients underwent standard thoracotomy and 13 underwent limited incision with the same anesthetic technique. During the first 24 hours after operation, there were large decreases in the results of spirometric tests of pulmonary reserve (forced expiratory volume in 1 second and forced vital capacity), but these decrements were consistently significantly smaller in the limited-incision group. Other tests of pulmonary function (mid-expiratory phase forced expiratory flow, alveolar-arterial oxygen gradient, and PaCO2), however, demonstrated similar postoperative changes in both groups. Similarly, there were no differences in pain scores, postoperative morphine requirements, complications, or length of hospital stay. Use of the limited muscle-sparing incision resulted in improved postoperative pulmonary reserve, but this did not translate into differences in other measures of postoperative convalescence.