Results of a prospective multicenter study on port-access coronary bypass grafting.

BACKGROUND: We reviewed the initial patient series of three institutions performing large volume port-access (PA) coronary artery bypass grafting (CABG) to evaluate the efficacy of this new procedure. METHODS: From October 1996 until June 1998, 302 consecutive patients underwent isolated CABG using the PA approach. Patients (mean age 60.7 years) were predominantly male (77.5%) and received a mean of 2.3 distal anastomoses; few were New York Heart Association class III or IV (15.9%). The distribution of the number of grafts was: 76 (25.2%) single, 110 (36.4%) double, 73 (24.2%) triple, and 43 (14.2%) four or more bypass grafts. The Society of Thoracic Surgeons (STS) Database data collection form was used prospectively by all three institutions to define patient risk factors and record outcomes. RESULTS: Total 30-day hospital mortality was 0.99% compared to the STS-database-model-predicted risk of 1.2%. Complication rates for the PA CABG patients compared with risk-matched morbidity rates from the STS data for CABG alone were: reoperation for bleeding, 3.3% versus 1.9%; ventilatory support more than 1 day, 1.7% versus 3.8%; stroke, 1.7% versus 1.2%; and perioperative transmural myocardial infarction 0% versus 1.3%. CONCLUSIONS: The STS CABG risk-adjusted model demonstrates that the 30-day mortality for patients undergoing PA CABG is lower than predicted for traditional CABG patients (confidence intervals not available). Likewise, the morbidity was low, with minimal ventilatory support, pulmonary complications, and atrial fibrillation. The port-access technique is an acceptable strategy for multivessel bypass grafting.

Pediatric cardiopulmonary bypass: a review of current practice.

Devices and techniques used for pediatric cardiopulmonary bypass are ever changing. There are frequently reports in the literature about new techniques and new devices. Periodic surveys are helpful because they reveal the actual extent to which these techniques and devices are applied to clinical practice. Advances in research are bringing about a better understanding of the intricate aspects of CPB and the effects of CPB on pediatric patients. There appears to be a trend from widely divergent approaches to CPB for pediatric patients to more uniformity in practice. For example, the use of membrane oxygenation and arterial line filtration has become universal, and there is an increase in the use of all types of safety devices. Techniques reported in the medical literature at the beginning of the decade, such as, the use of modified ultrafiltration, the use of centrifugal cell washers to process packed red blood cells before adding them to the prime, and the use of the antifibrinolytic drug, aprotinin, have become part of practice at a large number of pediatric heart centers. Periodic surveys are useful, as they provide a measurement of current practice. They also provide a historical record of the advances in the field.

A multicenter, double-blind, placebo-controlled trial of aprotinin for reducing blood loss and the requirement for donor-blood transfusion in patients undergoing repeat coronary artery bypass grafting.

BACKGROUND: Aprotinin is a serine protease inhibitor that reduces blood loss and transfusion requirements when administered prophylactically to cardiac surgical patients. To examine the safety and dose-related efficacy of aprotinin, a prospective, multicenter, placebo-controlled trial was conducted in patients undergoing repeat coronary artery bypass graft (CABG) surgery. METHODS AND RESULTS: Two hundred eighty-seven patients were randomly assigned to receive either high-dose aprotinin, low-dose aprotinin, pump-prime-only aprotinin, or placebo. Drug efficacy was determined by the reduction in donor-blood transfusion up to postoperative day 12 and in postoperative thoracic-drainage volume. The percentage of patients requiring donor-red-blood-cell (RBC) transfusions in the high- and low-dose aprotinin groups was reduced compared with the pump-prime-only and placebo groups (high-dose aprotinin, 54%; low-dose aprotinin, 46%; pump-prime only, 72%; and placebo, 75%; overall P = .001). The number of units of donor RBCs transfused was significantly lower in the aprotinin-treated patients compared with placebo (high-dose aprotinin, 1.6 +/- 0.2 U; low-dose aprotinin, 1.6 +/- 0.3 U; pump-prime-only, 2.5 +/- 0.3 U; and placebo, 3.4 +/- 0.5 U; P = .0001). There was also a significant difference in total blood-product exposures among treatment groups (high-dose aprotinin, 2.2 +/- 0.4 U; low-dose aprotinin, 3.4 +/- 0.9 U; pump-prime-only, 5.1 +/- 0.9 U; placebo, 10.3 +/- 1.4 U). There were no differences among treatment groups for the incidence of perioperative myocardial infarction (MI). CONCLUSIONS: This study demonstrates that high- and low-dose aprotinin significantly reduces the requirement for donor-blood transfusion in repeat CABG patients without increasing the risk for perioperative MI.

Alternative method of ultrafiltration after cardiopulmonary bypass.

A revised circuit design for modified ultrafiltration is presented rendering the technique more convenient for use after cardiopulmonary bypass when blood cardioplegia is used. The procedure employs a hollow-fiber ultrafiltration device attached to the cardioplegia circuit. A bubble trap, heat exchanger, and a pressure monitor are incorporated as safety features. The technique has been used in 80 patients (30 pediatric and 50 adult) and has been associated with relevant increases in colloid osmotic pressure and hematocrit.

A reliable bridge to cardiac transplantation: the TCI left ventricular assist device.

The Thermo Cardiosystems (TCI) HeartMate, a pneumatically driven, implantable left ventricular assist device, was designed for long-term support of the failing heart. Between February 1990 and August 1992, the HeartMate was implanted in 11 heart transplant candidates because of profound deterioration of left ventricular function. Patients had a mean cardiac index of 1.6 L.min-1 x m-2 and a mean pulmonary capillary wedge pressure of 33 mm Hg despite maximal pharmacologic support with at least three inotropic medications. In addition, 5 patients were being supported with an intraaortic balloon pump. Nine patients were bridged successfully to cardiac transplantation. The mean cardiac index after implantation of the left ventricular assist device was 3.2 L.min-1 x m-2. Support ranged from 2 to 143 days (mean duration, 60 days). One patient died early of low output secondary to right heart failure, and a second died of air embolism, which occurred intraoperatively. All surviving patients became fully ambulatory. There were no thromboembolic complications during a total of 658 patient-days of support on a regimen of only 80 mg of aspirin daily. The 9 bridged patients are currently alive 4 to 34 months after transplantation. The TCI HeartMate provides safe and effective hemodynamic support with low risk of complications and virtual freedom from thromboembolism on a regimen of minimal anticoagulation.

Endobronchial tuberculosis in children. A case report and review.

Unilateral obstructive emphysema seen on chest X-ray in a pediatric patient is usually associated with a foreign body in a bronchus. We present a 31-month-old female who presented with a 2-week history of increasing expiratory stridor. Endoscopic examination revealed a polypoid mass in the right main bronchus. Biopsies and cultures were consistent with endobronchial tuberculosis. We review the presentation and treatment of tuberculosis in children. Endobronchial tuberculosis is a rare complication of pulmonary tuberculosis which may result in stenosis of the bronchus.

Coronary artery bypass surgery: emerging trends in mortality.

In a consecutive series of 4,697 patients undergoing coronary artery bypass surgery, these risk factors were found to be significant for increased postoperative mortality: age greater than 70, female sex, unstable angina, prior myocardial infarction, hypertension, diabetes mellitus, and ejection fraction less than .40. A comparison by year (1980-1988) revealed a steadily increasing incidence of these risk factors. Future analysis of coronary artery bypass mortality should include risk-factor stratification.

A quality assurance model of operative mortality in coronary artery surgery.

Quality assurance in coronary artery bypass grafting (CABG) surgery requires a comparison of operative mortality against an accepted standard of care. Raw mortality statistics are unacceptable in this context, and risk factor analysis is essential. However, this principle has not been adequately demonstrated in previous reports. Our goal in this study was to develop a risk model of accepted CABG mortality and illustrate its proper use in coronary artery surgery. The model was derived from a Bayesian analysis of 6,630 patients undergoing CABG in the Coronary Artery Surgery Study (CASS) registry. Age, sex, ventricular function, previous myocardial infarction, extent of coronary artery disease, unstable angina, and surgical priority were used by the model to sort patients into risk categories. From January 1984 through December 1987, 840 patients underwent isolated CABG at our hospital. With raw mortality data, the 3.9% (33/840) mortality of our patients was significantly different from the 2.3% (153/6,630) CASS mortality (p less than 0.001). When our patients were entered into the CASS model for risk stratification, however, our CABG mortality conformed to the CASS experience. These results illustrate the fallacy of using raw mortality statistics for interinstitutional comparisons. This type of risk model is a fundamental element of CABG quality assurance.

Use of a Bayesian statistical model for risk assessment in coronary artery surgery.

A computerized statistical model based on the theorem of Bayes was developed to predict mortality after coronary artery bypass grafting. From January, 1984, to April, 1987, at our hospital, 700 patients underwent isolated coronary artery bypass grafting. The presence or absence of 20 risk factors was determined for each patient. The first 300 patients formed the initial database of the Bayesian predictive model, and the remaining 400 patients were prospectively evaluated in four groups of 100 each. Each group was prospectively evaluated and then incorporated into the database to update the model. There was good agreement between predicted and observed results. Bayesian theory is particularly suited to this task because it (1) accommodates multiple risk factors, (2) is tailored to one's specific practice, (3) determines individual, rather than group, prognosis, and (4) can be updated with time to compensate for a changing patient population. These flexible attributes are especially valuable in light of recent changes in the coronary artery bypass graft patient profile.

A comparison of patients with endoscopic esophageal perforations and patients with Boerhaave's syndrome.

A review was conducted to ascertain whether patients who suffered spontaneous postemetic esophageal rupture (Boerhaave's syndrome) experienced higher morbidity and mortality than patients who had endoscopic iatrogenic esophageal perforations. Review of the records of three medical centers from 1960 to 1985 identified 11 patients with Boerhaave's syndrome (group B) and 19 with iatrogenic perforations (group E). In group B, four patients were diagnosed greater than 24 h after perforation. Nine were treated surgically; of these one died. Two group B patients who were treated conservatively survived. In group E, only four patients were diagnosed greater than 24 h after perforation. Of 19 patients, 15 were treated surgically and four, medically. In group E, three patients died (one surgically and two conservatively treated). This study suggests that there is little difference in mortality between the two groups of patients as long as the diagnosis is made early and therapy is instituted promptly.

Bayesian statistical theory in the preoperative diagnosis of pulmonary lesions.

We used a computerized Bayesian algorithm to assist in the preoperative diagnosis of pulmonary lesions. One hundred consecutive patients who were undergoing exploratory thoracotomy for newly discovered pulmonary lesions were prospectively evaluated. The Bayesian model used a total of 44 preoperative clinical and roentgenographic factors to categorize the lesions as benign or malignant. The Bayesian algorithm correctly categorized 96 of the 100 lesions, thereby providing an accuracy of 96 percent. The sensitivity of the model was 98 percent and the specificity was 87 percent. All but two of the 85 malignant lesions were correctly categorized and 13 of the 15 benign lesions were correctly analyzed by the model. These results indicate that computer-assisted diagnosis using the Theorem of Bayes may provide valuable preoperative information for the management of selected patients.

Mediastinal hemangiomas.

Hemangiomas of the mediastinum are rare tumors. Fewer than 100 have been reported. This study reviews the cases of 15 patients with mediastinal hemangiomas confirmed pathologically. We analyzed and evaluated the presentation, evaluation, and treatment. Follow-up is available for 14 of the 15 patients and ranges from 15 months to 15 years. Eight of the 15 patients were seen with signs and symptoms related to the tumor. This presentation correlated with invasion of contiguous mediastinal structures by the tumor. Six patients underwent total excision and 6, subtotal excision. During follow-up, residual tumor did not spread, become symptomatic, or show evidence of malignant degeneration. Based on this analysis, we believe that in patients in whom total excision of this tumor can be accomplished only by hazardous resection, a subtotal resection should be performed.

Prevention of ventricular fibrillation after myocardial revascularization.

Ventricular fibrillation during reperfusion after aortic cross-clamping for coronary artery bypass grafting may cause subendocardial injury. We investigated the use of lidocaine to prevent ventricular fibrillation during this period. In a blind, prospective, randomized trial, 91 consecutive patients undergoing elective coronary artery bypass graft procedures were given lidocaine (2 mg/kg) or normal saline immediately before removal of the aortic cross-clamp. The groups were similar with respect to demographic, clinical, and intraoperative variables. Myocardial preservation techniques were similar in both groups. Of 47 patients receiving lidocaine, 38 recovered a supraventricular rhythm without ventricular fibrillation, compared with only 5 of 44 patients in the control group (p less than .001). When ventricular fibrillation occurred, patients in the control group required a greater number of direct-current countershocks (2.31 versus 1.86) to convert to sinus rhythm. Transient heart block, requiring temporary pacing, developed in 3 patients in the lidocaine group, compared with 1 patient in the control group. There was no significant difference between the groups in the requirement for perioperative inotropic support (6 of 47 versus 6 of 44) or the number of myocardial infarctions (2 of 47 versus 1 of 44), and there were no deaths in either group. Lidocaine infusion immediately before removal of the aortic cross-clamp significantly reduces the incidence of ventricular fibrillation during the reperfusion period after cardiopulmonary bypass.

Adult human endothelial cell enzymatic harvesting. Estimates of efficiency and comparison of crude and partially purified bacterial collagenase preparations by replicate microwell culture and fibronectin degradation measured by enzyme-linked immunosorbent assay.

Reliable enzymatic endothelial cell (EC) harvest methods are required for clinical EC seeding of vascular prostheses by methods analogous to those demonstrated in dogs. But crude collagenases used for EC harvest vary in efficacy and cytotoxicity, and purified collagenases reportedly give low EC yields. To compare different harvest methods, we studied growth curves of primary adult human saphenous vein EC (HSVEC) harvests plated in replicate microwell cultures. The EC yield, defined as attachment-capable ECs obtained per square centimeter of vein lumen, was estimated from the lowest number of ECs counted in lag phase before exponential growth began. With the use of morphometric studies of HSVs that were perfusion-fixed at their original dimensions, the baseline in situ density of ECs available for harvest from HSV was estimated at 1.3 X 10(5) EC/cm2. Crude (CBC) and partially purified bacterial collagenase (PBC) solutions at concentrations with equal levels of basement membrane lysis activity (BMLA) were compared by the replicate microwell method in a series of 21 harvests (six CBC, eight PBC, and seven enzyme-free control harvests). All 14 enzymatic harvests produced confluent EC cultures with no significant difference in mean harvest efficiency between CBC (12% of in situ EC number) and PBC (15%). However, PBC caused less degradation of human fibronectin (p less than 0.0001) as measured by an enzyme-linked immunosorbent assay employing a fibronectin-specific monoclonal antibody. These data suggest that chemically defined mixtures of pure enzymes with BMLA equal to the BMLA of crude collagenase might allow reliable EC harvesting without sacrifice in EC yield but with improved preservation of structures at the EC periphery. EC losses during initial vein dissection may have contributed to the low 12% to 15% efficiency we observed.

The cytotoxic effect of surgical glove powder particles on adult human vascular endothelial cell cultures: implications for clinical uses of tissue culture techniques.

Clinical use of autogenous endothelial cell (EC) seeding of vascular prostheses (VP) would require reliable methods for EC harvest for immediate seeding or primary culture in a hospital or operating room setting. Observation of glove powder particles (GPP) in failed primary adult human saphenous vein EC (AHSVEC) cultures led us to study the effect of surgical GPP on cultured AHSVEC. Addition of GPP to the culture medium of growing ASHVEC cultures reduced the cell counts in a dose-dependent fashion; the mean concentration of GPP required to produce a greater than 50% decrease in cell number was 1.5 +/- 0.8 (SD) X 10(4) GPP/ml (N = 10 experiments), equivalent to a mean dose of 36 micrograms glove powder per milliliter. The effect was seen within 24 hr of addition of GPP and was not due to interference with EC attachment and spreading or to changes in medium osmolality, pH, glucose, electrolyte, Ca2+, or Mg2+ content. Instead, the effect appeared to be due to a filterable toxin added during the final rubber-vulcanizing stage of glove manufacture, since pure cornstarch particles and epichlorhydrin-treated pure cornstarch did not prevent culture growth, whereas 0.2 micron filtrates of medium incubated with GPP taken directly from gloves were lethal. We conclude that filterable cytotoxic substances from GPP may be an avoidable cause of failure in EC seeding of VP, and may affect surgical wound healing as well.

The use of computed tomography in the evaluation of mediastinal masses.

A retrospective analysis was conducted to ascertain whether computed tomography had increased diagnostic accuracy while decreasing the number of tests needed in the preoperative assessment of patients with mediastinal masses. A total of 42 patients were entered into the study: Fifteen patients were evaluated before the advent of computed tomography (No CT) and 27 patients had computed tomography during their evaluation (CT). The No CT group comprised 10 male and five female patients (2:1 ratio); the age range was 8 months to 61 years. The CT group included 15 male and 12 female patients (1.25:1.0 ratio), the age range being 21 to 70 years. In each group, both invasive and noninvasive studies were done. Although the CT group had 40 noninvasive tests, 27 were computed tomographic scans. The additional 13 noninvasive tests and the five invasive tests added no significant diagnostic information. In the No CT group, preoperative evaluation as to the cystic or solid nature of the mass was correct only four of 13 times (31%). In the CT group, 22 of 25 patients had accurate assessment as to the cystic or solid nature of the lesions (88%). In addition, extension of the mass into other structures, consistent with malignancy, was correctly diagnosed preoperatively in nine of the patients in the CT group. Two had extension of the mass at operation not preoperatively diagnosed (82% accuracy). None of the No CT group was given an assessment of possible mass extension preoperatively. The results suggest that mediastinal masses can be evaluated by computed tomography with a high degree of accuracy for predicting the nature, size, location, and involvement of other organs by the mass. The use of other tests before resection generally yields little additional information.

Surgical implications of intraoperative postinfarction ventricular rupture.

This case report documents that ventricular myocardial rupture after acute infarction may seal with clot, only to rupture again with potentially lethal consequences. At exploration, the clot over a fresh rupture was intact. As closure was started, the clot disrupted, causing severe hemorrhage. Rupture was successfully repaired and the patient survived.

Acute diverticulitis following cardiac surgery.

Gastrointestinal complications requiring surgical correction following cardiopulmonary bypass most frequently involve the upper gastrointestinal tract. Surgical diseases of the colon are quite unusual in this setting. We recently performed cardiac surgery on three patients who developed acute diverticulitis requiring laparotomy in the early postoperative period. The presentation and management of this disorder after open heart surgery are discussed.

Late Mycobacterium chelonei bioprosthetic valve endocarditis: activation of implanted contaminant?

Mycobacterium chelonei contamination of the Hancock porcine heart valve prosthesis occurred in a few lots manufactured between October, 1975, and August, 1976. The unimplanted valves were recalled, but a number of valves in their cohort had already been implanted. This report describes a patient with Mycobacterium chelonei endocarditis of a Hancock bioprosthetic heart valve belonging to this cohort that occurred three years after implantation. We are aware of four similar instances of mycobacterial endocarditis and believe that these latent infections originated either from surgical inoculation or from implantation of a contaminated valve prosthesis. Other Hancock valves manufactured between October, 1975, and August, 1976, may harbor latent M. chelonei. We believe early valve replacement with aggressive combination antibacterial and antituberculosis therapy is essential for control of atypical mycobacterial valve endocarditis.

Pulmonary artery banding.

Two hundred nine children with congenital heart defects characterized by excessive pulmonary blood flow underwent pulmonary artery banding at The Hospital for Sick Children from January, 1972, through December, 1982. The indications for banding, rather than complete repair, varied with the type of cardiac defect as well as with the year of presentation to our hospital. A simplified method of estimating required band circumference has been developed for infants with ventricular septal defect, with or without major intracardiac mixing disorders. Infants with simple defects without intracardiac bidirectional mixing disorders receive a band at a circumference of 20 mm + 1 mm for each kilogram of body weight, whereas infants with bidirectional mixing disorders receive a band at a circumference of 24 mm + 1 mm for each kilogram of body weight. The overall operative mortality varies with the underlying cardiac defect and with associated medical conditions but is relatively low in the less-complicated cases. The use of a formula to predict a starting band circumference, with loosening only as required by cyanosis or bradycardia, allows predictable control of congestive symptoms and pulmonary hypertension in the majority of infants. The cumbersome measurement of pulmonary artery pressure and the unpredictable changes in pressure during anesthesia are avoided. Pulmonary artery banding remains an effective means of achieving satisfactory palliation in infants with congenital heart disease and excessive pulmonary blood flow.