Tea E. Acuff

Application of thoracoscopy for diseases of the spine

For anterior approaches to the thoracic spine, a posterolateral thoracotomy has been the standard approach. Recent expanded experience with video-assisted thoracic surgical techniques has allowed us to perform many thoracic spine procedures that previously required open approaches. These procedures include drainage of spinal abscesses, biopsy of vertebral bodies, discectomy for a herniated nucleus pulposus, and anterior releases for kyphoscoliosis. All procedures were successful, but experience is limited and follow-up still short. It is hoped that further experience will prove that this less invasive approach can be widely applied in the practice of thoracic spinal surgery.

Elimination of cardiopulmonary bypass improves early survival for multivessel coronary artery bypass patients.

BACKGROUND Coronary artery bypass graft (CABG) surgery performed without cardiopulmonary bypass (CPB) is currently increasing in clinical practice. Decreased morbidity associated with off-pump (OP) CABG in selected risk groups examined in relatively small, single institution groups has been the focus of most recent studies. The purpose of this study was to determine the independent impact of CPB on early survival in all isolated multivessel CABG patients undergoing surgery in two large institutions with established experience in OPCABG techniques. METHODS A review of two large databases employed by multiple surgeons in the hospitals of two institutions identified 8,758 multivessel CABG procedures performed from January 1998 through July 2000. In all, 8,449 procedures were included in a multivariate logistic regression analysis to determine the relative impact of CPB on mortality independent of known risk factors for mortality. Procedures were also divided into two treatment groups based on the use of CPB: 6,466 had CABG with CPB (CABG-CPB), 1,983 had CABG without CPB (OPCABG). Disparities between groups were identified by univariate analysis of 17 preoperative risk factors and treatment groups were compared by Parsonnets risk stratification model. Finally, computer-matched groups based on propensity score for institution selection for OPCABG were combined and analyzed by a logistic regression model predicting risk for mortality. RESULTS CABG-CPB was associated with increased mortality compared with OPCABG by univariate analysis, 3.5% versus 1.8%, despite a lower predicted risk in the CABG-CPB group. CPB was associated with increased mortality by multiple logistic regression analysis with an odds ratio of 1.79 (95% confidence interval = 1.24 to 2.67). An increased risk of mortality associated with CPB was also determined by logistic regression analysis of the combined computer-matched groups based on OPCABG-selection propensity scores with an odds ratio of 1.9 (95% confidence interval = 1.2 to 3.1). CONCLUSIONS Elimination of CPB improves early survival in multivessel CABG patients. Rigorous attempts to statistically account for selection bias maintained a clear association between CPB and increased mortality. Larger multiinstitutional studies are needed to confirm these findings and determine the most appropriate application of OPCABG.

Video-assisted thoracic surgery for the anterior approach to the thoracic spine

Standard anterior approach to the thoracic spine is by a posterolateral thoracotomy. Because of the morbidity associated with this incision, video-assisted thoracic surgery (VATS) has been used as a less invasive approach for many intrathoracic disease processes. We have applied VATS for anterior access to the thoracic spine. From April 1991 to September 1994, 95 patients underwent thoracic spine procedures using thoracoscopy as the sole method of anterior approach. Procedures performed include discectomy for herniation (n = 57), multilevel discectomy for correction of spinal deformity (27), corpectomy (9), and drainage of intervertebral disc space abscess (2). All levels of the thoracic spine from the T2-T3 level to the T12-L1 interspace were approached. Forty-four procedures were performed through the left side of the chest and 41 through the right. The planned procedure was accomplished by VATS in all but 1 patient who required conversion to an open procedure because of scarring from a previous spine procedure. Mean operative time was 2 hours 24 minutes (range, 45 minutes to 5 hours 10 minutes). Average chest tube duration was 1.4 days, and mean length of stay was 4.82 days (range, 2 to 21 days). Complications included intercostal neuralgia (6), atelectasis (5), excessive epidural blood loss (2,500 mL; 2) and temporary paraparesis in a scoliosis patient related to operative positioning. We conclude that VATS offers a new, less morbid anterior approach to the thoracic spine. Although there is a significant learning period, most procedures requiring an anterior access can be performed safely by this technique. The VATS approach mandates an expanded role for the thoracic surgeon in operative spine disease.

Percutaneous Localization of Pulmonary Nodules for Thoracoscopic Lung Resection

A limiting factor in removing pulmonary nodules by videothoracoscopic techniques is the inability to locate lesions deep within the substance of the lung. We describe a technique in which a hook wire commonly used to localize nonpalpable breast lesions is placed percutaneously into the lung nodule preoperatively. Using the wire anchored into the lung as a guide, the target lesion can be successfully identified and removed thoracoscopically.

Influence of diabetes on mortality and morbidity: off-pump coronary artery bypass grafting versus coronary artery bypass grafting with cardiopulmonary bypass

BACKGROUND Myocardial revascularization in diabetic patients is challenging with no established optimum treatment strategy. We reviewed our coronary artery bypass grafting experience to determine the impact of eliminating cardiopulmonary bypass on outcomes in diabetic patients relative to nondiabetic patients. METHODS From January 1995 through December 1999, 9,965 patients, of whom 2,891 (29%) had diabetes, underwent isolated coronary artery bypass grafting. Diabetic and nondiabetic patients were further divided into groups on the basis of cardiopulmonary bypass use. Twelve percent (346 of 2,891) of diabetic patients and 12% (829 of 7,074) of nondiabetic patients underwent coronary artery bypass grafting without cardiopulmonary bypass; the remainder had coronary artery bypass grafting with cardiopulmonary bypass. Nineteen preoperative variables were compared among treatment groups by univariate analysis. RESULTS Patients undergoing coronary artery bypass grafting without cardiopulmonary bypass compared with those having coronary artery bypass grafting with cardiopulmonary bypass had higher mean predicted mortalities (diabetic, 3.96% versus 3.72%, p = 0.83; nondiabetic, 3.03% versus 2.86%, p = 0.79). In nondiabetic patients, coronary artery bypass grafting without cardiopulmonary bypass provides an actual and risk-adjusted survival advantage over coronary artery bypass grafting with cardiopulmonary bypass (1.81% versus 3.44%, p = 0.0127; risk-adjusted mortality, 1.79% versus 3.61%, p = 0.007). This survival benefit of coronary artery bypass grafting without cardiopulmonary bypass was not seen in diabetic patients (2.89% versus 3.69%, p = 0.452; risk-adjusted mortality, 2.19% versus 2.98%, p = 0.42). Diabetic patients undergoing coronary artery bypass grafting without cardiopulmonary bypass had fewer complications, including decreased blood product use (34.39% versus 58.4%, p = 0.001), and reduced incidence of prolonged ventilation (6.94% versus 12.10%, p = 0.005), atrial fibrillation (15.90% versus 23.26%, p = 0.002), and renal failure requiring dialysis (0.87% versus 2.75%, p = 0.036). CONCLUSIONS The survival advantage in nondiabetic patients treated with coronary artery bypass grafting without cardiopulmonary bypass is not apparent in diabetic patients. Coronary artery bypass grafting without cardiopulmonary bypass in diabetic patients is nevertheless associated with a significant reduction in morbidity.

Determinants of operative mortality in reoperative coronary artery bypass grafting

Previously suggested risk factors for operative mortality in reoperative coronary artery bypass grafting are contradictory. Therefore, we analyzed our data of 622 patients who underwent reoperative bypass grafting from January 1986 through June 1993. Among these patients, 258 had saphenous vein grafts alone and 364 had internal mammary artery grafting, including unilateral (342 patients) and bilateral (22 patients) mammary artery grafting with or without additional saphenous vein grafting. Overall operative mortality was 11.4% for reoperation compared with only 3.6% for primary bypass grafting during the same time frame. To determine risk factors for mortality and the influence of internal mammary artery grafting on the outcome, we analyzed 82 variables (31 preoperative, 17 intraoperative, and 34 postoperative) by univariate analysis. Significant variables or the variables having a trend (p < 0.2) to be associated with the mortality were included in stepwise multiple logistic regression analyses. Two regression analyses were separately performed. Regression 1 only included preoperative and intraoperative variables whereas regression 2 included postoperative variables as well. The logistic regressions demonstrate that preoperative variables (low ejection fraction [p = 0.0002], old age [p = 0.003], female gender [p = 0.011], and history of arrhythmia [p = 0.023]), intraoperative variables (emergency operation [p = 0.0001] and long perfusion time [p = 0.0001]), and postoperative variables (complications) are independently associated with higher mortality. Unlike previously described results, aortic crossclamp time, route of cardioplegia, use of internal mammary artery, number of grafts, and year of operation are not associated with operative mortality. The identification of these risk factors may have important implications in further improvement of the results of reoperative coronary artery bypass grafting.

Aortic valve replacement: Determinants of operative mortality

Contradictory results have been reported regarding risk factors for aortic valve replacement (AVR). This study was designed to investigate determinants of operative mortality for AVR with emphasis on concomitant coronary artery bypass grafting (CABG) and old age. Between January 1986 and June 1992, 371 patients with a mean age of 61.99 +/- 0.76 years underwent AVR. There were 256 men (69.0%) and 115 women (31.0%). Twenty-six patients (7.0%) were 80 years old or older, and 97 (26.1%) were between 70 and 80 years old. Of these patients, 210 (56.6%) had isolated AVR, 142 (38.3%) had concomitant CABG, and 31 (8.4%) had concomitant mitral valve operations. Twenty patients (5.4%) underwent emergency operation. There were 33 operative deaths (8.9%). Univariate analysis and stepwise multiple logistic regression analysis were used to determine the risk factors for operative mortality. In the univariate analysis, 13 preoperative variables (sex, age, history of congestive heart failure, myocardial infarction, arrhythmia, functional class, class I/II versus III/IV, four variables related to aortic valve pathology, ejection fraction, left ventricular function) and 20 perioperative variables (emergency operation, individual surgeon, myocardial protection by type and route of cardioplegia, type of prosthesis, size of prosthesis, mean size by survival, small versus large size, concomitant procedure, concomitant CABG (versus others or AVR alone), concomitant mitral valve operation (versus others or AVR alone), concomitant CABG and MV operation, aortic cross-clamp time, cardiopulmonary bypass time, use and time of insertion of intraaortic balloon pump, low cardiac output, postoperative complications) were examined.(ABSTRACT TRUNCATED AT 250 WORDS)

Risk factors for operative mortality in elderly patients undergoing internal mammary artery grafting

From January 1986 through June 1992, 512 elderly patients (70 years and older) underwent internal mammary artery grafting (IMAG). The operative mortality in these patients was 7.62% (39 of 512), which was significantly higher than that (1.97% [60 of 3,047]; p < 0.0001) in younger patients (under 70 years old). To investigate the risk factors in the elderly, the data from the 512 patients were evaluated by univariate analysis and multiple logistic regression. Of 53 variables analyzed, nine preoperative variables (age, smoking history, congestive heart failure, myocardial infarction, New York Heart Association functional class, ejection fraction, left main artery disease, stenosis of the left anterior descending artery, and reoperation), three intraoperative variables (emergency operation, bilateral IMAG, and right IMAG), and nine postoperative variables were significantly associated with the higher mortality (p < 0.05). In particular, the operative mortality was significantly higher in the patients undergoing right IMAG (21.62% [8 of 37]) than that in patients only undergoing left IMAG (6.53% [31 of 475]; p < 0.004). The significant preoperative and intraoperative variables and the variables that have a tendency for correlation (p < 0.2) to mortality were included in a stepwise multiple logistic regression. The regression analysis demonstrated that right IMAG, reoperation, history of myocardial infarction, age, left main artery disease, history of smoking, and postoperative complications are the risk factors for the elderly undergoing IMAG. Therefore, particular care should be taken in those patients scheduled to undergo IMAG. The role of right IMAG in the elderly should be further clarified before universal acceptance of the technique in these patients.

Functional comparison between the human inferior epigastric artery and internal mammary artery: Similarities and differences

Although the inferior epigastric artery has been used as an alternative arterial graft for coronary artery bypass grafting, little is known about the contractile and relaxation characteristics of this artery. This study was designed to compare the pharmacologic reactivity of the two arterial conduits--the inferior epigastric artery and the internal mammary artery. Forty-one inferior epigastric artery ring segments from eight patients undergoing coronary grafting and 62 internal mammary artery ring segments were set up in organ baths under physiologic pressure. The contractility was determined from the contraction induced by the depolarizing agent potassium and receptor-mediated vasoconstrictor agents, norepinephrine, U46619, and endothelin-1. Endothelium-dependent relaxation was induced by the calcium ionophore A23187, a non-receptor agonist for endothelium-derived relaxing factor, and acetylcholine, a receptor agonist for endothelium-derived relaxing factor. Glyceryl trinitrate was used to study endothelium-independent relaxation. The maximal response (either contraction or relaxation) and the effective concentration causing 50% of the maximal response for these two arteries were compared. There was no difference (p > 0.05) either in the maximal contraction force (5.30 +/- 0.87 versus 4.76 +/- 0.89 gm for potassium, 5.13 +/- 0.67 versus 4.47 +/- 1.15 gm for norepinephrine, 8.04 +/- 1.23 versus 6.23 +/- 0.99 gm for U46619, and 4.88 +/- 0.69 versus 5.57 +/- 0.93 for endothelin-1 (n = 6 to 10 for each vasoconstrictor) or in the maximal relaxation induced by glyceryl trinitrate (86.46% versus 92.98%, n = 6) or by acetylcholine (20.72% versus 45.51%, n = 5) between the inferior epigastric artery and internal mammary artery. The effective concentration causing half maximal response to all vasoconstrictors and vasodilators was similar between the two arteries (p > 0.05). However, A23187 induced significantly less relaxation in the inferior epigastric artery (38.42 +/- 15.49%, n = 6) than in the internal mammary artery (71.89 +/- 7.17%, n = 9, p < 0.05). We conclude that contractility, endothelium-independent relaxation, and receptor-mediated endothelium-dependent relaxation are similar in the inferior epigastric artery and the internal mammary artery. However, the endothelium of this arterial graft has less ability to respond to the non-receptor-mediated endothelium-derived relaxing factor stimulant. The influence of this difference on the prevalence of atherosclerosis and long-term patency rate in the inferior epigastric artery remains to be studied.

Greater contractility of internal mammary artery bifurcation: Possible cause of low patency rates

Coronary artery bypass grafting using bifurcation of the internal mammary artery (IMA) has been reported to have a poor patency rate. To test the hypothesis that the contractility (tendency for spasm) is greater at the bifurcation than at the main IMA, segments of the bifurcation and the distal section of IMA taken from patients with coronary artery bypass grafts were studied in organ baths. The IMA rings were set up at a physiologic pressure. Concentration-response curves were established for norepinephrine, endothelin-1, U46619, potassium, and glyceryl trinitrate (precontracted with 10 nmol/L U46619). Contraction forces were standardized (gram per mm circumference) at a pressure of 100 mm Hg. The diameter was 1.50 +/- 0.08 mm (n = 38) for the bifurcation and 2.03 +/- 0.07 (n = 42) for the main IMA (p < 0.0001). The standardized contraction force was greater in the bifurcation than in the main IMA for norepinephrine (0.82 +/- 0.06 versus 0.54 +/- 0.1; p = 0.02) and endothelin-1 (1.07 +/- 0.11 versus 0.69 +/- 0.07; p = 0.02). No differences were seen for potassium, U46619, or glyceryl trinitrate, whereas the effective concentration that induced 50% of maximal effect for U46619 was 6.17-fold lower in the bifurcation than in the main IMA (9.14 +/- 0.28 versus 8.35 +/- 0.09 -log M; p = 0.003), indicating higher sensitivity in the bifurcation.(ABSTRACT TRUNCATED AT 250 WORDS)