Richard A. Schmaltz

Heparin-induced thrombocytopenia in open heart surgical patients: Sequelae of late recognition

Most patients undergoing open heart operations have had exposure to heparin for diagnostic and/or therapeutic procedures. Heparin antibody formation and heparin-induced thrombocytopenia with repeat heparin administration can cause high morbidity and mortality from thrombotic complications, especially when delay in diagnosis occurs. From 1981 to 1991, heparin-induced thrombocytopenia was diagnosed in 82 of 4,261 open heart surgical patients (1.9%). Platelet counts less than 100 x 10(9)/L (100,000/microL) or new or recurring thrombotic events prompted suspicion of heparin-induced thrombocytopenia. Heparin-dependent antibody was diagnosed preoperatively in 12 patients (group I) and postoperatively in 70 patients (group II). Heparin was not given postoperatively in group I patients, and complications in this group were limited to bleeding in 3 patients. There were no thromboembolic events and all patients survived. Group II patients had late recognition of heparin-dependent antibody postoperatively, and heparin exposure was continued for varying periods postoperatively. Thirty-seven group II patients (53%) had bleeding complications and 31 (44%) had thromboembolic complications. These complications led to death in 23 group II patients (33%). Heparin-dependent antibody may occur in patients having open heart operations and is a major cause of morbidity and mortality if not diagnosed early with cessation of heparin therapy.

Elevated hemidiaphragm after cardiac operations: Incidence, prognosis, and relationship to the use of topical ice slush

We have reviewed chest roentgenograms of 745 patients before hospital dismissal after cardiac operations and serially to determine the incidence and prognosis of elevated hemidiaphragm and any relationship to the use of topical ice slush (TIS) in myocardial preservation. All patients had similar myocardial preservation techniques including moderate systemic hypothermia and 4 degrees C saline solution poured over the heart at aortic clamping. During a 12-month period, TIS was added to the saline bath. Two (2.4%) of 84 patients before TIS and 5 (2.5%) of 201 consecutive patients operated on since discontinuing TIS had elevated hemidiaphragm on the predismissal roentgenogram. Of 460 patients in whom TIS was employed, 109 (23.7%) had elevated hemidiaphragm (p less than 0.001). When TIS was employed, elevated hemidiaphragm developed in 72 (26%) of 280 patients without internal mammary artery takedown versus 13 of 33 patients (39.4%) with takedown of the internal mammary artery (p = 0.047). Ninety-nine patients with elevated hemidiaphragm were available for follow-up at 1 month, at which time 79 (79.8%) continued to have elevated diaphragm. At 1 year, 14 (21.9%) of 64 patients had persistent diaphragm elevation. We conclude that TIS predisposes to elevated diaphragm and that the incidence is increased when the internal mammary artery is harvested.

Coronary revascularization in the elderly: Determinants of operative mortality

Over a 13-year period, 668 patients 70 years of age or older underwent isolated primary coronary artery bypass grafting at our institution. There were 472 men and 196 women, ranging from 70 to 90 years of age (median age, 74 years). Hospital mortality was 5.2% (35/668). In patients 70 to 79 years of age, hospital mortality was 4.2% (25/600), whereas in patients 80 years of age or older, mortality was 14.7% (10/68; p < 0.001). Twenty-seven clinical or hemodynamic variables hypothesized as predictors of operative mortality were examined. Mortality was higher in women than in men (9% versus 3.6%; p = 0.006). Those who died were a mean of 3 years older (77 versus 74 years old; p < 0.05) and were more likely to have unstable angina or Canadian class III or IV angina (p < 0.01). Patients requiring urgent operations, preoperative intraaortic balloon assist, intravenous nitroglycerin, or inotropic agents, and those with preoperative hypotension or cardiac arrest were most likely to die in the hospital (p < 0.001). Multivariate logistic regression analysis revealed advancing age, female sex, bypass time, urgency of operation, preoperative cardiac arrest, and unstable angina as primary determinants of mortality (p < 0.05). Although mortality after coronary artery bypass grafting increases with age, the greatest risk of death is in the acutely ill patient with few options for management other than surgical intervention.

Incidence and predictors of supraventricular dysrhythmias after pulmonary resection.

BACKGROUND Patients undergoing pulmonary resection were evaluated prospectively in an effort to determine the incidence of and predictors for the development of postoperative supraventricular dysrhythmias. Specifically, we wished to test the hypothesis that the incidence of postoperative supraventricular dysrhythmias is dependent on the magnitude of pulmonary resection. METHODS One hundred sixteen patients undergoing pulmonary resection had continuous Holter monitoring preoperatively, the day of operation, and the second postoperative day, as well as continuous cardiac monitoring throughout hospitalization. Holter interpretation was blinded to extent of resection. RESULTS Twenty-six patients underwent pneumonectomy, 7 bilobectomy, 47 lobectomy, and 36 wedge resection. Twenty-six patients (22.4%) had supraventricular dysrhythmias, all atrial fibrillation +/- flutter. The incidence of atrial fibrillation with pneumonectomy, bilobectomy, single lobectomy, and wedge resection was 46.1%, 14.3%, 17.0%, and 13.8%, respectively (p < 0.005 pneumonectomy versus others). Overall, 31% of patients having pneumonectomy required pharmacologic therapy for dysrhythmia compared with 16% of patients having lesser resections, (p = 0.03). The peak incidence of onset of atrial fibrillation occurred on postoperative days 2 and 3 and lasted for less than 1 to 7 days, average 2.5 days. The average age of patients with dysrhythmias (64 years) was greater than those without (58 years) (p = 0.039). Thirty pre- and postoperative variables tested were not found to be significant predictors for development of postoperative atrial fibrillation. CONCLUSIONS Atrial fibrillation occurs commonly after pulmonary resections but is not predictable. Development of atrial fibrillation is not dependent on the magnitude of pulmonary resection but is associated with the procedure pneumonectomy for reasons not elucidated.

Tracheostomy: a risk factor for mediastinitis after cardiac operation

BACKGROUND We studied whether tracheostomy after coronary artery bypass grafting (CABG) is associated with higher incidence of mediastinitis and mortality, and whether shorter intervals between median sternotomy and tracheotomy are associated with higher incidence of mediastinitis. METHODS Patients (n = 6,057) undergoing CABG since March 1977 were reviewed. Patients requiring tracheostomy and those developing mediastinitis were identified. Mediastinitis diagnosis required positive culture of mediastinal tissue or fluid. RESULTS After CABG, 88 patients had tracheostomy performed (1.45%). Seven patients receiving tracheostomy after developing mediastinitis were excluded. Of the remaining 81 patients, 7 developed mediastinitis (8.6%) compared with 44 of 5,969 (0.7%) who did not require tracheostomy (p < 0.001). Mortality in tracheostomy patients was 24.7% (20 of 81) compared with 5.2% in patients not requiring tracheostomy (316 of 5,969; p < 0.001). Patients not developing mediastinitis had tracheostomy placement an average of 25 days after CABG compared with 18.7 days for those developing mediastinitis (p = 0.141). CONCLUSIONS Tracheostomy after CABG is associated with increased incidence of mediastinitis and mortality. In this review, the time interval between CABG and tracheostomy was not predictive of mediastinitis. A larger sample size would be required to be confident that there is no correlation.

Centrifugal pumps: description of devices and surgical techniques

BACKGROUND Because of simplicity of application, universal access, and low cost, centrifugal pumps are commonly used for short-term mechanical cardiac assist. Indications and techniques for application of this technology continue to evolve. METHODS The clinical experience with 151 patients undergoing centrifugal mechanical cardiac assist at the University of Missouri-Columbia has been reviewed. We have compared commonly available centrifugal pumping systems in vitro and in vivo for characteristics that might distinguish them. RESULTS Centrifugal pumps have been found to be well suited for use in surgery on the thoracic aorta, for extracorporeal membrane oxygenation and for postcardiotomy cardiac mechanical assist. Complications associated with centrifugal mechanical assist are predictable and common but potentially can be reduced by improved surgical techniques and anticoagulation strategies. In vitro and in vivo experimentation with available centrifugal pumps reveals nuances characteristic of each of the devices. CONCLUSIONS All centrifugal pumps presently available are less destructive to blood cellular elements compared with roller pumps. With familiarity, all can function satisfactorily for short-term mechanical assist with no compelling evidence that favors any particular centrifugal pump system clinically available. Centrifugal pumps are ideally suited for left heart bypass during surgery on a thoracic aorta and for short-term application as may be required for postcardiotomy mechanical assist. Centrifugal pump technology should be part of the armamentarium of all cardiothoracic surgeons.

Internal mammary artery graft to pulmonary vasculature fistula : a cause of recurrent angina

Recurrent angina pectoris developed in a 59-year-old man 3 years after coronary artery bypass grafting using the left internal mammary artery. Cardiac catheterization showed a fistula between the left internal mammary artery and the pulmonary vasculature. This is an unusual documented case of postoperative internal mammary artery graft to pulmonary vasculature fistula after coronary artery bypass grafting. Division of this fistulous communication resulted in resolution of the patients angina.

Randomized, Prospective Comparison of First- and Second-Generation Cephalosporins as Infection Prophylaxis for Cardiac Surgery

Surgical wound infections after cardiovascular surgery may be life threatening and are resource intensive. Second-generation cephalosporins are purported to have a broader antimicrobial spectrum than first-generation cephalosporins and, therefore, may be more efficacious for infection prophylaxis. We have conducted a randomized prospective study of 702 patients undergoing open heart surgery to test the hypothesis that the second-generation cephalosporin, cefuroxime, will be more efficacious for infection prophylaxis than the first-generation cephalosporin, cefazolin. Patients were randomized to receive cefazolin 1 g intravenously every 8 hours for 48 hours begun 1 hour preoperatively plus 1 g after 4 hours of surgery (8 doses, n = 425) or cefuroxime 1.5 g 1 hour prior to surgery plus 1.5 g every 12 hours for 3 additional doses (4 doses, n = 277). Infection was defined as a draining wound with or without a positive culture. There was no difference in the wound infection rate between the groups (p = 0.68). Chest wound infections occurred in 2.1% of patients treated with cefazolin and 2.9% of patients treated with cefuroxime (p = 0.79). The rate of true mediastinitis requiring exploration and drainage was 0.7% in both groups (p = 0.084). Leg infections occurred in 6.6% of cefazolin-treated patients and 5.6% of cefuroxime-treated patients (p = 0.83). The second-generation cephalosporin, cefuroxime, did not reduce the incidence of wound infection when compared with the first-generation cephalosporin, cefazolin. Since institutional antibiotic acquisition and administration costs vary, careful analysis of these factors will allow determination of the most cost-effective infection prophylaxis regimen in cardiac surgery.

Use of centrifugal pumps for postcardiotomy ventricular failure: Technique and anticoagulation

BACKGROUND Centrifugal pumps have been employed most commonly for postcardiotomy mechanical support after intraaortic balloon pumping has failed. Despite their effectiveness in some patients, morbidity remains high. METHODS Our clinical experiences with centrifugal pumps were reviewed with particular attention to common morbidity such as bleeding, coagulopathy, and thromboembolism. Evolution of cannulation techniques and anticoagulation strategies were defined. Morbidity during early and more recent experience was compared. RESULTS Deranged coagulation and excessive mediastinal bleeding were commonly observed in patients undergoing centrifugal mechanical assist for postcardiotomy cardiogenic shock. Evolved strategies to reduce blood loss included meticulous cannulation techniques, early use of blood components, and an aggressive policy of mediastinal reexploration. Thromboembolism occurred with centrifugal mechanical assist, was underestimated by clinical events, and dictated pursuit of improved anticoagulation strategies and device refinement. A clinically significant trend of decreasing morbidity from early to recent experience was observed. CONCLUSIONS Increasing clinical experience with centrifugal mechanical assist appears to result in a clinically relevant decrease in morbidity.

Autopsy findings in patients on postcardiotomy centrifugal ventricular assist.

Reported experience with ventricular assist devices (VAD) routinely includes the rate of thromboembolic events, which is commonly calculated from clinically evident findings. Fifty-four patients have had postcardiotomy circulatory support with the Sarns centrifugal device at our institution. We have reviewed 43 patients who failed to survive VAD support to compare the thromboembolism rate diagnosed clinically to that determined at autopsy. In the 35 patients who had no autopsy, there was one clinically apparent thromboembolic event (2.3%). In eight similar patients who had autopsy, there was no clinically apparent thromboembolism. Five of these eight patients (63%) had acute thromboembolic infarcts determined at autopsy. Three had evidence of pulmonary thromboembolism, two cerebrovascular infarction, two liver infarcts, two splenic infarcts, two kidney infarcts, and one each gastric, pancreatic, prostate, adrenal, cervical, and ileal infarcts. All had left and/or right ventricular infarctions. It is concluded that patients dying following VAD have commonly suffered perioperative myocardial infarction. When evaluating complications associated with VAD, one should consider that the true incidence of thromboembolic events is underestimated by clinical findings.