Anticoagulation for stroke prevention in new atrial fibrillation after coronary artery bypass graft surgery.

BACKGROUND: The benefit of early anticoagulation for stroke prophylaxis in atrial fibrillation after coronary artery bypass graft (CABG) surgery is uncertain. We therefore studied what proportion of ischemic strokes in patients with atrial fibrillation early after CABG surgery were potentially preventable by anticoagulation with warfarin. METHODS: We reviewed medical records from 2264 patients with isolated CABG performed during a period when our institution had no policy on anticoagulation for postoperative atrial fibrillation. The outcome was ischemic stroke within 30days postoperatively and verified with computed tomography (CT) in patients with new postoperative atrial fibrillation for more than 48h. RESULTS: New, postoperative atrial fibrillation occurred in 403 (17.8%) of the patients and 191 of those (47.4%) were not started on warfarin at 48hours. Eight patients developed CT-verified ischemic stroke, which occurred on postoperative day 1-3 in 4 patients and in 3 patients was of the lacunar type. In two patients (stroke day 25 and day 30) warfarin could have been preventive. In another patient with onset of neurological symptoms on postoperative day 8 (4days from onset of the arrhythmia), systemic anticoagulation might have limited the severity of the stroke but warfarin therapy would not likely have reached therapeutic levels within 2days. CONCLUSION: The preventive effect of warfarin on early stroke associated with new atrial fibrillation after CABG seems limited. Treatment with warfarin during the hospitalization has to take the risk of bleeding, particularly into the pericardium, as reported in the literature, into account.

Off-pump coronary artery bypass grafting for acute heparin-induced thrombocytopenia.

Surgical revascularization of coronary arteries is problematic for patients with heparin-induced thrombocytopenia because the available nonheparin anticoagulants cannot be reversed pharmacologically. We used three-vessel off-pump coronary artery bypass grafting in a patient with heparin-induced thrombocytopenia, as it allowed us to use substantially lower doses of nonheparin anticoagulant (danaparoid sodium), compared with procedures requiring cardiopulmonary bypass.

Medtronic Mosaic porcine bioprosthesis: midterm investigational trial results.

BACKGROUND: The midterm clinical and hemodynamic performance of the Medtronic Mosaic porcine bioprosthesis was evaluated in a regulatory trial. METHODS: In nine Canadian centers, 802 bioprostheses (560 aortic and 242 mitral) were implanted between September 1994 and April 1999 in patients with a mean age of 70 years. RESULTS: Survival for aortic valve replacement at 4 years was 84.4%+/-3.1%. Freedom from valve-related or unexplained death was 95.6%+/-1.9%; structural valve deterioration, 100.0%; reoperation, 96.2%+/-1.7%; major thromboembolism, 96.1%+/-1.8%; and major antithrombotic-related hemorrhage, 96.4%+/-1.7%. Echocardiographic derived mean systolic gradient was 13.4 mm Hg at 4 years with an indexed effective orifice area of 0.7 to 0.8 cm2/m2. A significant decrease in left ventricular mass was shown over time in all valve sizes. Survival for mitral valve replacement at 4 years was 79.2%+/-6.8%. Freedom from valve-related or unexplained death was 96.5%+/-3.4%; structural valve deterioration, 100%; reoperation, 97.0%+/-3.2%; major thromboembolism, 95.7%+/-3.8%; and major antithrombotic-related hemorrhage, 95.0%+/-4.2%. Echocardiographically measured averaged mean diastolic gradient was 4.5 mm Hg. CONCLUSIONS: The Medtronic Mosaic bioprosthesis is safe and effective in both the aortic and mitral positions. The valve has low gradients in both positions and excellent left ventricular mass regression in the patients with aortic valve replacement.

Mediastinoscopy as a routine outpatient procedure.

We reviewed our experience performing mediastinoscopy as an outpatient procedure. From January 1, 1987, to December 31, 1992, 1,015 of 1,062 cervical mediastinoscopies were performed on an outpatient basis. There were no operative deaths. Complications developed in 14 patients, 10 of whom required hospitalization. Two additional patients were hospitalized for social reasons. Supraventricular arrhythmia was the most frequent complication requiring admission to the hospital. This article documents the ability to perform mediastinoscopy safely as an outpatient procedure and discusses why this is our preferred approach in managing patients with lung cancer.

Prognostic significance of computed tomography in resected N2 lung cancer.

We reviewed 124 patients from 1982 to 1988 who had a resected primary non-small cell lung cancer metastatic to mediastinal (N2) lymph nodes and a preoperative assessment of the mediastinum with computed tomography of the chest. Sixty-three patients studied had computed tomographic evidence of mediastinal lymph node enlargement. In these patients the survival at 5 years was only 6.6%, compared with the 5-year survival of 13.5% in 61 patients in whom the mediastinum was normal. Plain chest roentgenography with evidence of mediastinal adenopathy did not predict a poorer outcome. In addition, patients with tumors located in the left upper lobe were found to have an improved survival. These patients had a 5-year survival of 20.8%. Tumor histology, central location of the tumor, extranodal extension, and type of resection did not result in a significant survival difference.

Intra-abdominal abscesses in Crohn's disease.

We reviewed 22 patients who had intra-abdominal abscesses secondary to Crohn's disease. A total of 29 abscesses were discovered. These included superficial and deep intraperitoneal as well as pelvic and retroperitoneal abscesses. Diagnosis was aided by ultrasound and computer tomographic scanning. Barium studies continue to play an important role in delineating the extent of bowel involvement and fistulization. Treatment varied depending on the location and size of the abscess. The need for ultimate bowel resection was determined in the majority of cases by the presence of fistulization between the abscess cavity and the bowel. The terminal ileum or neoterminal ileum were almost always involved.

Contribution of cardiogenic oscillations to gas exchange in constant-flow ventilation.

The contribution of cardiogenic oscillations to gas exchange during constant-flow ventilation was examined in 11 dogs. With the use of two variations of cardiopulmonary bypass to maintain the systemic and pulmonary circulation, the influence of cardiogenic oscillations was removed by arresting the heart. Cardiac arrest by ventricular fibrillation was associated with a mean decrease in alveolar ventilation of 43% in five dogs on right and left heart bypass. However, successful defibrillation and return of the prearrest level of alveolar ventilation could not be achieved; thus we studied six dogs on left heart bypass. Alveolar ventilation decreased an average of 37% with cardiac arrest, and defibrillation resulted in a return of alveolar ventilation to 81% of the prearrest value. These results are consistent with previous predictions that cardiogenic oscillations are an important mechanism of gas transport during constant-flow ventilation.

Neutropenic responses to intradermal injections of Escherichia coli. Effects on the kinetics of polymorphonuclear leukocyte emigration.

Killed Escherichia coli organisms injected intradermally into rabbits induced significant neutropenia and provoked a rapid rise in body temperature. Both the magnitude and the duration of the neutropenia were dose-dependent. After recovery from neutropenia, the rabbits became refractory to its redevelopment when subsequently given an equivalent dose of E coli. The influence of neutropenia and the subsequent refractory period on the rate of polymorphonuclear leukocyte (PMN) emigration into inflammatory sites was examined. Killed E coli organisms (6 X 10(8) per site) were injected into two groups of 20 intradermal sites in each rabbit. The first group (Group F) preceded the second (Group S) by 6 hours. The kinetics of PMN emigration, quantitated with 51Cr-labeled cells, differed in the two groups. In Group S sites an intense PMN influx was measured at 0-4 hours, and subsequently the extent of PMN emigration rapidly declined. In Group F sites a minute PMN influx was detected during the first 4 hours, coinciding with a marked neutropenia. The maximal PMN influx into Group F sites was measured between 6 and 10 hours. Microscopic sections at 4 hours showed a scanty PMN infiltrate and numerous bacteria in the dermis of Group F sites, while extensive phagocytosis of bacteria by PMNs was apparent in Group S sites. By comparing the extent of bacterial phagocytosis in 4-hour-old sites with the magnitudes of PMN emigration between 6 and 10 hours in both groups, we concluded that the phagocytic elimination of killed E coli was not a major mechanism regulating the cessation of local PMN emigration. Instead, we propose that tachyphylaxis or desensitization of sites to inflammatory factors released from E coli is the responsible mechanism.