Vibhu R. Kshettry

Safety and efficacy of off-pump coronary artery bypass grafting

BACKGROUND We evaluated the application of the off-pump coronary artery bypass (OPCAB) procedure relative to safety and efficiency as measured by operative mortality postoperative complications and longitudinal outcome. METHODS Three hundred and fifty OPCAB patients were compared to 3,171 on-pump or conventional coronary artery bypass (CCAB) patients between January 1, 1997 and December 31, 1998. The groups were divided into three preoperative predicted risk categories: low-risk (0 to 2.59%), medium-risk (2.6 to 9.9%), and high-risk (> or =10%). Society of Thoracic Surgeons National Cardiac Surgery Database definitions and predicted risk group models were utilized to compare all preoperative, intraoperative, and postoperative variables using univariate analysis. RESULTS Overall comparison of the immediate outcome of CCAB and OPCAB shows little statistical significance in the variables analyzed. The operative mortality was 3.4% in both groups. When the immediate outcome was compared between groups (CCAB vs OPCAB), as well as individual risk groups (low, medium, and high), similar patterns of operative variables and postoperative complications were observed. The operative mortality in the low-risk group was 1.1% for CCAB and 1.4% for OPCAB; 7% for CCAB and 6% for OPCAB in the medium-risk group; and in the high-risk group 28.5% for CCAB compared to 7.7% for OPCAB group (p = 0.008). Short-term follow-up shows a trend of increased recurring angina and reinterventional procedures in the OPCAB patients. CONCLUSIONS Safety for OPCAB is assessed through retrospective data review. Longitudinal follow-up for survival, reintervention, and quality of postoperative document efficacy and patency rates, compared to on-pump procedures, is mandatory. This study documented the immediate safety of the OPCAB procedure. Preliminary findings at 1-year follow-up is an important finding in this study, but it is not conclusive at this time. Long-term longitudinal follow-up is required to assess the future effectiveness of OPCAB.

Risk factors for the development of bronchiolitis obliterans syndrome after lung transplantation

OBJECTIVE This study identifies specific clinical and immunologic factors in lung transplant recipients that influence the subsequent development of chronic allograft dysfunction. METHODS The study group consisted of 132 consecutive patients who received lung allografts (76 single, 25 bilateral single, and 31 heart-lung) and survived at least 90 days. One hundred twenty-one patients were used in the analysis that modeled time to development of histologic obliterative bronchiolitis or bronchiolitis obliterans syndrome. RESULTS Variables noted to have an effect on the time to development of bronchiolitis obliterans syndrome included cytomegalovirus pneumonitis (RR = 3.2, p = 0.001), late acute rejection (RR = 1.3, p = 0.02), human leukocyte antigen mismatches at the A loci (RR = 1.8, p = 0.02), total human leukocyte antigen mismatches (RR = 1.4, p = 0.04), and absence of donor antigen-specific hyporeactivity (52% vs 100% survival free from bronchiolitis obliterans syndrome at 2 years; p = 0.005). Cytomegalovirus pneumonitis had a significant effect on time to obliterative bronchiolitis (RR = 3.6, p = 0.0005), as did donor antigen-specific hyporeactivity (52% vs 100% survival free from obliterative bronchiolitis at 2 years; p = 0.01). In multivariate analysis, cytomegalovirus pneumonitis (RR = 3.2, p = 0.02), human leukocyte antigen mismatches at the A loci (RR = 2.4, p = 0.006), and late acute rejection (RR = 1.3, p = 0.02) were identified as predictors of bronchiolitis obliterans syndrome. Cytomegalovirus pneumonitis was associated with time to development of histologic obliterative bronchiolitis (RR = 2.3, p = 0.02). CONCLUSIONS Several risk factors were associated with the development of chronic allograft dysfunction, which, in turn, had a significant impact on long-term survival. Early identification of lung allograft recipients with risk factors for the development of bronchiolitis obliterans syndrome may allow modification in immunosuppression and antiviral therapy to potentially decrease the prevalence of this disorder.

Early and Late Airway Complications After Lung Transplantation: Incidence and Management

BACKGROUND Airway anastomosis complications continue to be a source of morbidity for lung transplant recipients. METHODS This study analyzes incidence, treatment, and follow-up of airway anastomotic complications occurring in 127 consecutive lung transplant airway anastomoses (77 single lung and 25 bilateral sequential lung). Complications were categorized as stenosis (11), granulation tissue (8), infection (7), bronchomalacia (5), or dehiscence (3). Follow-up after treatment ranged from 6 months to 4 years. RESULTS Nineteen airway anastomosis complications (15.0%) occurred in 18 patients. Telescoping the airway anastomosis reduced the complication rate to 12 of 97 (12.4%), compared with 7 of 30 (23.3%) for omental wrapping, (p = 0.15). Complications developed in 13 of 77 single-lung airway anastomoses (16.9%) versus 6 of 50 bilateral sequential lung recipients (12.0%). Treatment consisted of stenting (9 airway anastomoses), bronchodilation (8), laser debridement (4), rigid bronchoscopic debridement (2), operative revision (2), and growth factor application (2). There was no difference in actuarial survival between patients with or without airway anastomosis complications (p = 1.0). CONCLUSIONS Airway anastomosis complications can be successfully managed in the immediate or late postoperative period with good outcome up to 4 years after intervention.

Does multivessel, off-pump coronary artery bypass reduce postoperative morbidity?

BACKGROUND Off-pump coronary artery bypass (OPCAB) is an emerging procedure. It is assumed that elimination of cardiopulmonary bypass for coronary artery bypass grafting has the potential for reducing postoperative morbidity. This review evaluates the safety and impact of multivessel OPCABG as compared to CABG. METHODS A retrospective review of 744 patients undergoing multivessel coronary artery bypass between January 1, 1997, and March 31, 1999, was done. The total population was divided into two groups: group A (n = 609 cardiopulmonary bypass) and group B (n = 135 OPCAB). This consecutive study cohort was elective status, full sternotomy with three or more distal anastomoses performed at a single institution. RESULTS The mean risk adjusted predicted mortality was 2.3% in group A and 2.7% in group B (p = NS), with the mean number of distal anastomosis being greater in group A (3.8 vs 3.5/patient, p < 0.001). Major postoperative complications were similar but were not statistically significant between groups. Postoperative blood loss and use of blood transfusions were the only significant variables (p < 0.001). CONCLUSIONS Multivessel OPCABG can be safely performed in selected patients. Elimination of cardiopulmonary bypass did not significantly reduce postoperative morbidity. Prospective randomized trials and long-term follow-up are needed to better define patient selection and the role of OPCABG.

Is low ejection fraction safe for off-pump coronary bypass operation?

BACKGROUND Does the manipulation of the heart during off-pump coronary artery bypass (OPCAB) procedure further compromise the hemodynamic stability of a patient with depressed left ventricular function compared with the conventional coronary artery bypass (CCAB) approach? Does this manipulation induce a more dramatic hypoperfused state that may contribute to an increase in the incidence of related complications or mortality? This retrospective review of data attempted to answer the above concern. METHODS Between January 1, 1998, and June 30, 1999, 177 patients with ejection fractions of 30% or less underwent full sternotomy coronary artery bypass grafting at our institution. Of these patients, 45 underwent OPCAB procedures and 132 patients underwent CCAB. Pre-, intra-, and postoperative variables as identified by The Society of Thoracic Surgeons National Cardiac Surgery Database were compared using univariate and logistical regression analysis. RESULTS Despite recognized hemodynamic derangement during cardiac displacement, these groups of OPCAB patients appeared to tolerate the procedure well. Univariate analysis of cardiac enzyme leak and blood loss was statistically significant in the OPCAB patients. Utilizing regression analysis, cardiopulmonary bypass was the only predictor for all postoperative complications. CONCLUSIONS Multivessel coronary artery bypass utilizing the OPCAB approach in patients with depressed left ventricular function of equal to or less than 30% is appropriate and applicable. Analysis of CCAB and OPCAB variables was nonsignificant except for operative and postoperative blood loss and peak cardiac enzyme leak. Attention to intraoperative detail and hemodynamic management could be credited for the success with OPCAB.

Experimental large-animal model of obliterative bronchiolitis after lung transplantation

Obliterative bronchiolitis is a major cause of long-term morbidity after lung transplantation. It is characterized by small-airway inflammation and occlusion by fibrous tissue. The pathogenesis is uncertain. To study this disease, we developed a model of posttransplantation obliterative bronchiolitis using genetically defined miniature swine. Group 1 (n = 2) received a left lung autograft; group 2 (n = 7), a left lung allograft. Group 2 recipients were given cyclosporine, prednisone, and azathioprine for 3 months, then immunosuppression was tapered and discontinued over 1 month. The animals were observed for an additional 2 months, then sacrificed. Lung grafts in both groups were monitored with serial bronchoalveolar lavages and transbronchial biopsies for 6 months. After sacrifice, lung grafts underwent histopathologic and immunohistochemical examination. No allograft had histologic evidence of acute rejection or peribronchiolar infiltrate during the first 3 months of immunosuppression. During the tapering period, airway changes characterized by severe peribronchiolar lymphocytic infiltrates were seen. Bronchoalveolar lavages of allografts showed significantly increased lymphocyte counts with CD8+ cells predominating. After the discontinuation of immunosuppression, transbronchial biopsy and autopsy specimens showed progressive fibrous inflammatory occlusion of bronchioles. Immunohistochemical staining demonstrated increased expression of MCH class II antigen on the bronchiolar epithelium and increased dendritic cells and CD4+ lymphocytes. None of these changes were seen in group 1. Our findings suggest obliterative bronchiolitis is an immunologically mediated phenomenon related to chronic graft rejection after lung transplantation. This model will allow systematic study of the pathogenesis of obliterative bronchiolitis and possible therapeutic intervention.

Multidisciplinary Standardized Care for Acute Aortic Dissection Design and Initial Outcomes of a Regional Care Model

> “No physician can diagnose a condition he never thinks about.” > > — Michael DeBakey Patients with acute aortic dissection (AAD) have an in-hospital mortality of 26%, and for those patients with type A AAD, the mortality risk is 1% to 2% per hour until emergency surgical repair is performed.1,2 It is therefore critical that AAD be recognized promptly and that surgical care be provided expeditiously. Data from the International Registry of Acute Aortic Dissection (IRAD) indicate that the median time from emergency department (ED) presentation to definitive diagnosis of AAD is 4.3 hours, with an additional 4 hours between diagnosis and surgical intervention for type A patients.2,3 A portion of the delay to surgery is often the result of the patients presenting to smaller community hospitals underequipped to manage emergent AAD. Transfer to high-volume aortic care centers with highly specialized facilities and expertise is routine, but even at such centers, current surgical mortality is 25%.4 In an effort to address factors that delay AAD recognition and optimal management, a standardized, quality-improvement protocol for the regional treatment of AAD was developed and implemented with the goal of providing consistent, integrated, and coordinated care for patients with AAD throughout all phases of care. Modeled, in part, after a successful regional program for ST-segment elevation myocardial infarction,5, the specific aims of the program were to decrease the time from hospital arrival to diagnosis and treatment and to improve clinical outcomes for patients with AAD. A collaborative team designed program elements directed at (1) increasing awareness and knowledge of AAD among emergency care providers, (2) standardizing optimal care for AAD through the use of a formal protocol, (3) improving care coordination and communication across disciplines, and (4) providing …

Surfactant dysfunction in lung preservation

We studied the effect of lung preservation on the surfactant system in rats. Lung surfactant is necessary to maintain normal lung mechanics, and hence normal lung function. We evaluated lung mechanics with pressure-volume (P-V) curves, and analyzed biochemical changes of surfactant in bronchoalveolar lavage (BAL) fluid. Additionally, we determined wet to dry weight ratios (W/D). We defined five study groups. In group I (controls) we harvested lungs without pulmonary artery flushing, then evaluated them immediately. In group II we flushed lungs through the pulmonary artery (PA) with hypothermic modified Euro-Collins solution (mECS), then removed and studied them immediately to determine the consequences of PA flushing alone. In groups III, IV, and V we flushed lungs with mECS, then stored them in normal saline (NS) for 6 hr (group III); in NS for 12 hr (group IV); or in mECS for 12 hr (group V). In groups III, IV, and V we evaluated lungs after storage. All four experimental groups showed significant changes in lung mechanics and surfactant biochemistry, compared with controls. Lungs in groups III, IV, and V showed additional changes in lung mechanics and surfactant biochemistry compared with group II. The W/D in stored lungs (groups III, IV, and V) was significantly higher than in controls and group II. We conclude that lung preservation induces deleterious changes in the surfactant system. Surfactant alterations are evident immediately after pulmonary artery flushing, and increase in severity with storage.

Deep venous thrombosis and pulmonary embolism after lung transplantation

The incidence of deep venous thrombosis or pulmonary embolism after lung or heart-lung transplantation has not been well defined. Pulmonary embolism may be of particular concern in the postoperative period owing to an inadequately developed or absent collateral bronchial circulation and potential risk of pulmonary infarction. Fourteen (12.1%) of 116 patients undergoing either lung (n = 87) or heart-lung (n = 29) transplantation developed thromboembolic complications 10 days to 36 months after operation. Deep vein thrombosis developed in nine patients, including three with upper body thrombosis related to indwelling central venous catheters. Seven patients (6%) had pulmonary embolism, and three of them died. Resolution of pulmonary embolism was successfully accomplished by selective pulmonary artery infusion of urokinase in three patients without complications. Our experience indicates that deep vein thrombosis and pulmonary embolism are significant problems after lung transplantation. Mortality is high in those patients in whom pulmonary embolism develops. Therefore, a comprehensive prevention protocol is warranted.

Unilateral volume reduction after single-lung transplantation for emphysema

BACKGROUND Single-lung transplantation has become accepted therapy for patients with end-stage emphysema. Hyperinflation of the native lung can occur after single-lung transplantation with mediastinal shifting and compression of the transplanted lung. A volume reduction operation (pneumectomy) [corrected] may relieve symptoms of dyspnea and improve exercise tolerance. METHODS Three of 66 patients who underwent single-lung transplantation for emphysema had development of native lung hyperexpansion and mediastinal shifting causing compression of the transplanted contralateral lung at 12, 17, and 42 months after transplantation. There were 2 men and 1 woman. Unilateral volume reduction was performed without complication in all 3 patients. RESULTS All patients were noted to have marked improvement in chest radiographs after volume reduction, substantial relief of dyspnea, and improvement in exercise tolerance. An improvement in pulmonary function test results was noted in 1 patient, but tests were not done for the other 2 patients. CONCLUSIONS Patients with chronic obstructive pulmonary disease who undergo single-lung transplantation may have symptomatic hyperexpansion of the native lung requiring volume reduction months to years after transplantation. Unilateral volume reduction can be safely performed in the posttransplantation period.