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Biomedical subjects

Michael J Mack

Publications and source records attributed to Michael J Mack.

At least 55 records · Page 3Linked to original sources
PubMed2004

First-year outcomes of beating heart coronary artery bypass grafting using proximal mechanical connectors.

BACKGROUND: To determine the extended results of mechanical connectors we compared the 1-year outcomes of patients having beating heart coronary artery bypass surgery with at least one sutured or mechanically connected proximal vein graft anastomosis. METHODS: From May 2001 to December 2001, 166 patients were identified as having undergone off-pump bypass grafting utilizing at least one St. Jude symmetry aortic connector (St Jude Medical Anastomotic Technology Group, St. Paul, MN). Follow-up for major adverse cardiac events (MACEs), which is defined as cardiac mortality, myocardial infarction, or revascularization of a previous target vessel, was obtained on 162 patients (97.6%). A control group of 159 patients was identified from a cohort of patients having beating heart surgery with one or more sutured proximal vein graft anastomosis in the preceding year. The MACE follow-ups were obtained in 136 patients (85.6%) by direct telephone contact. RESULTS: Patients with connectors showed an accelerated number of MACEs beginning approximately 180 days from the time of surgery and stabilizing at approximately 300 days. Logistic regression analysis identified the presence of diabetes as a significant preoperative risk factor predisposing patients to earlier onset of MACEs (p = 0.03) with an odds ratio of 2.9 (95% confidence interval, 1.1 to 7.6). Insulin dependent diabetics showed no differences between connector and control patients in the frequency or timing of MACEs. Connector patients using oral hypoglycemic agents demonstrated a significant deviation (p = 0.01) from a similar control population in the prevalence and timing of MACEs. CONCLUSIONS: Connector patients showed an increased incidence of early MACEs. These events were characterized by an increased requirement for early target vessel revascularization and were predominantly in noninsulin-dependent diabetics.

Aged↗
PubMed2004

Are unaudited records from an outcomes registry database accurate?

BACKGROUND: Data from outcomes registry databases are being increasingly used for peer review and public reporting. However, administrative and clinical databases are mostly unaudited; thus, their accuracy has not been verified. METHODS: Outcomes data from all coronary artery bypass operations from a single cardiac surgery practice were entered into The Society of Thoracic Surgeons (STS) National Cardiac Database. From our practice of 18 surgeons, we audited 247 (10%) of the clinical records of patients undergoing surgery in 2001 and correlated them with all 315 elements of the STS National Cardiac Database for verification of accuracy. Inaccuracies were defined as a disagreement with a nominal or categorical variable or, for continuous variables, as the value not being within a predetermined window. When discrepancies existed, the hospital clinical record was assumed to be accurate. Outcomes discrepancies were then analyzed by four major categories: components of the preoperative risk algorithm, operative mortality, major complications, and other outcomes. RESULTS: Discrepancies were noted in 5% (16) or fewer of the audited fields for 98.8% of the records. Of the 32 variables in the mortality risk algorithms, discrepancies were present in fewer than 10% of the audits on 30 of the 32 variables. More than 95% of the audited charts had zero or one discrepancy in the seven most important variables in the mortality risk models. Operative mortality was determined to be completely accurate with no discrepancies between the database and the audited clinical record. Among major complications, the error rate was less than 1% for all complications except prolonged ventilation (4.0%). A higher rate of discrepancies did exist in some of the other variables, including discharge medications (14.1%) and ventilator time (36.4%). CONCLUSIONS: A detailed audit of a clinical outcomes registry database demonstrated that the major fields within this specific database including operative mortality, major complications, and the significant factors in the risk algorithm were highly accurate. Process improvement factors were identified to further increase the accuracy of data collection.

Cardiac Surgical Procedures↗
PubMed2004

A prospective multicenter trial of bipolar radiofrequency ablation for atrial fibrillation: early results.

BACKGROUND: The Cox-Maze III remains the gold standard for the surgical treatment of atrial fibrillation. However, the "cut-and-sew" technique is time consuming and technically challenging. The pulmonary veins are the source of ectopy in the majority of patients with atrial fibrillation. The safety and efficacy of bipolar radiofrequency to electrically isolate the pulmonary veins was evaluated in a prospective multi-center trial. METHODS: Beginning in January 2002, 30 patients at three medical centers underwent pulmonary vein isolation using bipolar radiofrequency and were followed for 6 months. Twenty-four of the patients also underwent a modified Cox-Maze III. Electrical isolation of the pulmonary veins was confirmed with intraoperative pacing. Pulmonary vein patency was assessed by magnetic resonance imaging or three-dimensional computed tomography in 15 patients at 1 month. RESULTS: Mean age was 60.9 +/- 11.7 years. Nineteen patients had paroxysmal atrial fibrillation. All pulmonary veins were isolated in every patient. The left pulmonary veins underwent 3.0 +/- 1.4 applications for a total of 26.4 +/- 10.5 seconds. The right pulmonary veins underwent 2.8 +/- 1.1 applications for a total of 26.3 +/- 12.6 seconds. There was no operative mortality. At 1 month, imaging revealed no evidence of pulmonary vein stenosis. At 6 months, 96% of patients were in normal sinus rhythm. CONCLUSIONS: The use of bipolar radiofrequency for electrical isolation of pulmonary veins and to replace other Cox-Maze III incisions is safe and effective at controlling atrial fibrillation. This emerging technology may shorten and simplify the surgical management of atrial fibrillation.

Aged↗
PubMed2004

Comparison of coronary bypass surgery with and without cardiopulmonary bypass in patients with multivessel disease.

BACKGROUND: Coronary artery bypass grafting can now be performed with or without cardiopulmonary bypass. Our objective was to determine whether off-pump coronary artery bypass grafting is associated with better early outcomes compared with conventional coronary artery bypass grafting. METHODS: In 4 centers with off-pump coronary surgery experience, a retrospective analysis of all coronary artery bypass grafting in a 3-year period was performed. Groups were compared to determine selection criteria, mortality, and morbidity, then computer-matched by propensity score to control for selection bias. Multivariate logistic regression identified risk factors predictive of mortality. Specific subgroups most likely to benefit were identified. RESULTS: In all, 17,401 isolated coronary artery bypass grafts were performed, 7283 (41.9%) off-pump coronary artery bypass grafts and 10,118 (58.1%) conventional coronary artery bypass with cardiopulmonary bypass. Factors determining selection of patients for off-pump coronary artery bypass grafting included female gender (55.5% vs 44.5%), preexisting renal failure (57.0% vs 43.0%), and reoperations (52.6% vs 47.4%). Operative mortality was 2.8%; off-pump coronary artery bypass grafting versus conventional coronary artery bypass with cardiopulmonary bypass (1.9% vs 3.5%, P <.001) had the same predicted risk. Of the patients with multivessel disease, 11,548 were matched by propensity scoring. Mortality was significantly less in the off-pump coronary artery bypass grafting group (2.8% vs 3.7%, P <.001). By multivariate logistic regression analysis of the matched sample, predictors for mortality were female gender (odds ratio 1.83, confidence interval 1.37-2.44), preexisting renal failure (odds ratio 2.85, confidence interval 2.64-4.95), history of stroke (odds ratio 1.74, confidence interval 1.08-2.80), previous coronary artery bypass grafting surgery (odds ratio 4.22, confidence interval 2.92-6.09), use of cardiopulmonary bypass (odds ratio 2.08, confidence interval 1.52-2.83), and recent myocardial infarction (odds ratio 2.31, confidence interval 1.68-3.22). Cardiopulmonary bypass was predictive of mortality in reoperations, female patients, and patients aged >or= 75 years. Off-pump coronary artery bypass grafting was associated with less morbidity, including reductions in blood transfusion (32.6% vs 40.6%, P <.001), stroke (1.4% vs 2.1%, P =.002), renal failure (2.6% vs 5.2%, P <.001), pulmonary complications (4.1% vs 9.5%, P <.001), reoperation (1.7% vs 3.2%, P <.001), atrial fibrillation (21.1% vs 24.99%, P <.001), and gastrointestinal complications (3.6% vs 4.8%, P =.02). CONCLUSION: In 4 centers with beating-heart operation experience, there is an overall early benefit in off-pump surgery, especially in patients traditionally considered at high risk for coronary artery bypass grafting.

Adult↗
PubMed2004

Cerebral dysfunction following cardiopulmonary bypass is a fact: what are the solutions?

Focal and diffuse cerebral dysfunction following cardiopulmonary bypass are multifactorial complications that occur with coronary artery bypass grafting. Controversy exists regarding quantification and duration of diffuse cerebral dysfunction. Multiple measures can be undertaken from preoperative screening to intraoperative and postoperative management to decrease the most common complication occurring after coronary artery bypass surgery.

Central Nervous System Diseases↗
PubMed2003

Patient selection and current practice strategy for off-pump coronary artery bypass surgery.

OBJECTIVE: Previous studies comparing off-pump coronary artery bypass surgery (OPCABG) to conventional techniques utilizing cardiopulmonary bypass (CABG-CPB) have failed to provide patient selection guidelines. We sought to determine guidelines, attempting to rectify the limitations of previous studies. METHODS AND RESULTS: A retrospective analysis of prospectively collected data from the Society of Thoracic Surgeons National Database, from January 1999 through December 2000, identified 204 602 multivessel coronary artery bypass (CABG) patients. Unadjusted and risk-adjusted odds ratios (OR) were calculated to compare OPCABG and CABG-CPB morbidity and mortality. A propensity model was developed to identify factors associated with selection for OPCABG. All off-pump patients were pair-matched with on-pump patients based on their propensity to receive an off-pump procedure. Off-pump patients, 8.8% of the total, had significantly different patient characteristics than the on-pump group. Characteristics associated with OPCABG selection included fewer diseased vessels, absence of left main disease, fewer bypass grafts, no previous CABG, older age, chronic lung disease, and renal failure. Unadjusted and risk-adjusted odds ratios indicate a significant off-pump survival benefit and decreased morbidity including stroke and renal failure in the overall group. Propensity matching also showed a significant OPCABG survival benefit [OR (95% CI) 0.83 (0.72, 0.96)]. Subgroup analysis of propensity-matched groups identified off-pump survival benefits in patients with previous CABG (OR=0.53), diabetics (OR=0.66), LVEF between 30% to 50% (OR=0.75), females (OR=0.79), and age 66 to 75 years (OR=0.80). CONCLUSIONS: OPCABG imparts some survival benefit to most patient subgroups. Higher risk patients including those undergoing reoperative CABG, diabetics, and the elderly may gain the most benefit.

Aged↗
PubMed2003

Advances in the treatment of coronary artery disease.

Initial pioneering efforts of direct coronary artery bypass were all performed on a beating heart. Although originally introduced into cardiac surgery for the repair of intracardiac defects, the ability of John Gibbon's heart-lung machine to create a motionless, bloodless operative field catalyzed coronary artery bypass surgery. During the ensuing decades tens of millions of patients benefited from coronary revascularization on cardiopulmonary bypass. As we celebrate the 50th anniversary of the invention of the heart-lung machine the landscape of interventional treatment of coronary artery disease has shifted dramatically. Although instrumental in the genesis of the field of coronary revascularization, the role of the heart-lung machine has now diminished. Two thirds of all coronary revascularization is now performed by percutaneous approaches and one fourth of all coronary artery bypass grafting procedures are performed without the heart-lung machine. However owing to the complexity of patients now requiring revascularization as well as recently introduced incremental improvements to cardiopulmonary bypass including coated, low prime circuits, closed integrated systems, and pharmacologic adjuncts Gibbon's heart-lung machine will continue to play an integral role in this field.

Angioplasty, Balloon, Coronary↗
PubMed2003

Safety and efficacy of minimally invasive atrial septal defect closure.

BACKGROUND: Atrial septal defects (ASDs) have been surgically closed with low mortality utilizing the conventional sternotomy approach (CSA). The technical ease of ASD closure has triggered interest in minimally invasive closure (MIC) to obviate the morbidity associated with sternotomy. Our study assesses the safety and efficacy of minimally invasive ASD closure. METHODS: Preoperative, intraoperative, and postoperative data were collected on 68 patients (39 CSA, 29 MIC) who underwent ASD closure from January 1997 to August 2002. Using univariate analysis of 17 preoperative risk factors there was no statistically significant difference between the two groups. RESULTS: MIC resulted in equivalent success rates in ASD closures, with similar morbidity, no mortality, and a significant difference in postoperative length of stay (3.93 +/- 1.6 days versus 5.36 +/- 2.51 days, p = 0.006). CONCLUSIONS: In experienced hands, MIC is an excellent alternative to CSA in ASD closure.

Adult↗
PubMed2003

Initial experience with proximal anastomoses performed with a mechanical connector.

BACKGROUND: The Symmetry Bypass System Aortic Connector (St Jude Medical, Inc) is a novel device for the construction of sutureless proximal anastomoses. The connector allows attachment of saphenous vein grafts to the aorta without requiring aortic clamping. We report our initial clinical experience with this device. METHODS: In a 2-month period from May to July 2001, a total of 139 consecutive proximal anastomoses were performed in 67 patients using the connector. All procedures were performed on a beating heart without cardiopulmonary bypass or any aortic clamping. Intraoperative variables and postoperative results were prospectively collected and retrospectively analyzed. RESULTS: Of 139 consecutive proximal anastomoses 138 (99.3%) were successfully completed with the device. One anastomosis required suture revision because of misdeployment. Six anastomoses (4.3%) required an additional suture for leak. Predeployment problems included connector loading/preparation malfunction in 10 grafts (7.2%), five because of human error and five technical failure. There was no operative mortality, perioperative myocardial infarction, or stroke. Vessels bypassed included the circumflex system (n = 59), right coronary artery and branches (n = 48), diagonal branch (n = 26), and left anterior descending coronary artery (n = 6). At a mean follow-up of 7 months, survival was 94.1% and survival free of major adverse cardiac and cerebrovascular events (MACCE) was 88.1%. CONCLUSIONS: Initial clinical experience with a sutureless proximal saphenous vein graft to aorta anastomosis performed with a mechanical connector demonstrates safety, reliability, and ease of use. Surmounting a brief learning curve improves the subtleties of device loading and deployment. Further benefits will be determined in an ongoing randomized study.

Adult↗
PubMed2003

Conversion in off-pump coronary artery bypass grafting: an analysis of predictors and outcomes.

BACKGROUND: The incidence, predictive factors, and outcomes related to conversion from off-pump coronary artery bypass (OPCAB) to on-pump coronary artery bypass grafting (ONCAB) have not been well defined. We sought to determine the incidence of conversion, predictive factors, and any associated adverse consequences. METHODS: From January 2000 through June 2002, 1,644 patients underwent nonemergent OPCAB with 61 patients requiring conversion from OPCAB to ONCAB. These groups were retrospectively compared by univariate and multivariate regression analysis. The converted group was then computer matched 1:3, to a cohort of ONCAB patients to determine differences in outcomes. RESULTS: The overall conversion rate was 3.71%. Converted patients compared with a computer-matched ONCAB patients had a higher incidence of operative mortality (18.0% versus 2.7%, p < 0.001). Urgently converted patients had a higher incidence of postoperative cardiac arrest (25% versus 1.1%, p < 0.001), multisystem organ failure (10.7% versus 0.6%, p < 0.001), vascular complications (7.1% versus 1.1%, p = 0.03), and perioperative myocardial infarction (10.7% versus 1.1%, p = 0.02). Predictive factors for conversion were surgeon early in OPCAB experience (odds ratio [OR] 4.4), previous CABG (OR 2.8), and congestive heart failure (OR 2.0). The need for urgent-emergent conversion was highly predictive for operative mortality (OR 7.3) compared with elective conversion. CONCLUSIONS: Patients undergoing urgent-emergent but not elective conversion from OPCAB to ONCAB had a significantly higher risk of mortality and morbidity compared with patients whose procedure was initially ONCAB. Variables predictive of conversion included previous CABG, congestive heart failure, and surgeons early in OPCAB experience.

Cardiopulmonary Bypass↗
PubMed2003

Beating heart surgery: does it make a difference?

Beating heart techniques were introduced into coronary artery bypass graft (CABG) surgery in the mid 1990s in an attempt to decrease the complications associated with the use of cardiopulmonary bypass. Significant advances in technique and technology, including suction stabilizers and exposure devices, have now allowed all coronary vessels to be routinely approached without the support of cardiopulmonary bypass, while maintaining hemodynamic stability. Currently, approximately 25% of all CABG is performed without cardiopulmonary bypass in the United States. An extensive body of literature attests to the strong interest in the technique and the outcomes available for analysis. Although randomized trials do not yet show a mortality benefit, they are all underpowered to do so. A review of large retrospective databases does appear to demonstrate a mortality benefit, but patient selection contributes bias. Strong evidence of benefit exists for blood loss/transfusion, postoperative renal failure, sternal infection, myocardial injury, extubation time, length of stay, and cost savings. Particular benefit is apparent in high-risk patient subgroups, including the elderly, reoperative patients, and those with significant comorbidities. Off-pump CABG does appear to make a difference in improved outcomes by maintaining the excellent results of traditional on-pump CABG, but with less perioperative complications.

Cardiopulmonary Bypass↗
PubMed2002

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 Parsonnet's 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.

Aged↗
PubMed2002

Obliteration of femoral artery pseudoaneurysm by thrombin injection.

BACKGROUND: Femoral artery pseudyoaneurysms are a common complication after femoral access for transcatheter procedures, frequently requiring operative repair. We review the safety and efficacy of a novel nonsurgical method of pseudoaneurysm treatment METHODS: From June 1998 to November 2001, a total of 47 femoral artery pseudoaneurysms in 46 patients were treated by bedside ultrasound-guided injection of dilute topical thrombin. All pseudoaneurysms occurred after femoral access for transcatheter procedures, and were diagnosed clinically and confirmed with ultrasound imaging. Clinical follow-up was performed and included ultrasound (2 hours to 1 month) in 64.4% of patients, including any patient with a symptomatic or clinical change. RESULTS: Pseudoaneurysms ranged in size from 1.5 to 4.5 cm. Of 47 pseudoaneurysms, 45 were successfully obliterated on the initial injection. After successful obliteration of pseudoaneurysm, 1 patient sustained thrombosis of the tibioperoneal trunk that required surgical embolectomy, yielding a complication rate of 2%. Four pseudoaneurysms recurred after initially successful obliteration. In 1 of these cases, the patient was taken directly to surgery, and 3 were successfully treated with repeat injection, for an overall success rate of 93.6%. CONCLUSIONS: Obliteration of femoral artery pseudoaneurysm by injection is safe and effective, and may be associated with decreased morbidity. Recurrent pseudoaneurysms may be safely reinjected, with a high success rate.

Aneurysm, False↗
PubMed2002

Outcomes experience with off-pump coronary artery bypass surgery in women.

BACKGROUND: It has been well documented that women have higher morbidity and mortality rates than men following coronary artery bypass graft (CABG) surgery. In view of this evidence, we investigated the following question: compared with on-pump CABG surgery, is there benefit to off-pump CABG surgery in women? METHODS: Our investigation analyzes patient mortality and 13 procedure complications controlling for 35 variables representing patient characteristics and comorbid conditions, and for procedure characteristics for a population of 16,871 consecutive women undergoing off-pump and on-pump CABG surgery at 78 hospitals for the period January 1998 to June 2001. RESULTS: Mean comparisons reveal that the mortality rate for women undergoing off-pump CABG surgery is nearly a percentage point lower than for women undergoing on-pump surgery (3.12 vs 3.90; p = 0.052). The complication rates for all complications analyzed (shock/hemorrhage, neurologic, cardiac, respiratory, renal, acute renal failure, adult respiratory distress syndrome, implant infection, postoperative infection, septicemia, pneumonia, and peripheral vascular) were lower for women off-pump than women on-pump with the exception of mechanical complications. Logistic regression results reveal, after controlling for 35 relevant patient characteristics, comorbid conditions and procedure characteristics, that women undergoing on-pump CABG surgery experience a 42% higher mortality rate (p = 0.0239) than women undergoing off-pump CABG surgery. CONCLUSIONS: Evidence suggests that off-pump CABG surgery may be better for women than on-pump CABG surgery because it appears to reduce mortality and respiratory complications, shorten lengths-of-stay, and increases discharges directly home. None of the 12 other complications investigated demonstrated an advantage for women undergoing on-pump surgery relative to those receiving off-pump surgery.

Aged↗
PubMed2002

Video-assisted thymectomy for myasthenia gravis: an update of a single institution experience.

OBJECTIVE: Video-assisted thymectomy was introduced in 1992 as a minimally invasive alternative for the treatment of myasthenia gravis. As experience with this technique is limited and follow-up short, we present this expanded and updated experience for purposes of validation of the technique. METHODS: Thirty-eight video-assisted thymectomies for myasthenia gravis were performed in our institution between March 1992 and March 2002. Two patients were lost to follow-up. We analyzed clinical results of 36 patients (14 males and 22 females) with a mean age of 41.2 years. Preoperative clinical staging was assessed by the newly recommended Myasthenia Gravis Foundation of America Clinical Classification. Clinical status at follow-up was assessed by the Myasthenia Gravis Foundation of America Postintervention Status classification. RESULTS: There was no perioperative mortality or long-term morbidity. One of 38 (2.6%) patients required conversion to limited thoracotomy for bleeding. The mean length of hospital stay was 1.64 days (range 0-8 days) with a median stay of 1 day. The mean length of follow-up is 53.24 months (range 4-126 months). Overall clinical improvement at follow-up was observed in 30 of 36 (83.0%) patients, with five of 36 (14.0%) patients in complete stable remission. CONCLUSIONS: Video-assisted thymectomy for myasthenia gravis provides acceptable clinical long-term results by a minimally invasive approach comparable to standard surgical approaches to the disease. The presented data is reported in accordance with the new guidelines by Myasthenia Gravis Foundation of America Task Force for valid comparison with future studies.

Adolescent↗
PubMed2002

Robotics and coronary artery surgery.

Significant progress in cardiac surgery, and specifically the surgical management of coronary artery disease, has been due in large part to enabling technology. Robotic systems have been recently developed and refined for use in cardiac surgery to facilitate, among other procedures, a totally endoscopic approach to coronary artery bypass surgery. These systems enhance precision through endoscopic approaches by specifically addressing the inherent limitations of conventional endoscopic coronary microsurgical instrumentation via computerized, digital interface, telemanipulation technology. With a combined experience of 125 patients, several groups have independently demonstrated the clinical feasibility of totally endoscopic coronary artery bypass with two commercially available robotic telemanipulation systems. Additional enabling technology is needed to overcome the challenges currently limiting development and widespread application of totally endoscopic off-pump multivessel coronary artery bypass surgery.

Animals↗