Biomedical subjects

James S Gammie

Publications and source records attributed to James S Gammie.

12 recordsLinked to original sources

PubMed2006

Bedside tool for predicting the risk of postoperative dialysis in patients undergoing cardiac surgery.

BACKGROUND: Estimation of an individual patient's risk for postoperative dialysis can support informed clinical decision making and patient counseling. METHODS AND RESULTS: To develop a simple bedside risk algorithm for estimating patients' probability for dialysis after cardiac surgery, we evaluated data of 449,524 patients undergoing coronary artery bypass grafting (CABG) and/or valve surgery and enrolled in >600 hospitals participating in the Society of Thoracic Surgeons National Database (2002-2004). Logistic regression was used to identify major predictors of postoperative dialysis. Model coefficients were then converted into an additive risk score and internally validated. The model also was validated in a second sample of 86,009 patients undergoing cardiac surgery from January to June 2005. Postoperative dialysis was needed in 6451 patients after cardiac surgery (1.4%), ranging from 1.1% for isolated CABG procedures to 5.1% for CABG plus mitral valve surgery. Multivariable analysis identified preoperative serum creatinine, age, race, type of surgery (CABG plus valve or valve only versus CABG only), diabetes, shock, New York Heart Association class, lung disease, recent myocardial infarction, and prior cardiovascular surgery to be associated with need for postoperative dialysis (c statistic=0.83). The risk score accurately differentiated patients' need for postoperative dialysis across a broad risk spectrum and performed well in patients undergoing isolated CABG, off-pump CABG, isolated aortic valve surgery, aortic valve surgery plus CABG, isolated mitral valve surgery, and mitral valve surgery plus CABG (c statistic=0.83, 0.85, 0.81, 0.75, 0.80, and 0.75, respectively). CONCLUSIONS: Our study identifies the major patient risk factors for postoperative dialysis after cardiac surgery. These risk factors have been converted into a simple, accurate bedside risk tool. This tool should facilitate improved clinician-patient discussions about risks of postoperative dialysis.

Aged↗

PubMed2006

CTLA4-Ig-based conditioning regimen to induce tolerance to cardiac allografts.

BACKGROUND: Transplant rejection and toxicity associated with chronic immunosuppressive therapy remain a major problem. Mixed hematopoietic chimerism has been shown to produce tolerance to solid organ transplants. However, currently available protocols to induce mixed hematopoietic chimerism invariably require toxic pre-conditioning. In this study, we investigated a non-toxic CTLA4-Ig-based protocol to induce donor-specific tolerance to cardiac allografts in rats. METHODS: Fully mismatched, 4 to 6 week old ACI (RT1.A(a)) and Wistar Furth (RT1.A(u)) rats were used as cell/organ donors and recipients, respectively. Recipients were treated with CTLA4-Ig 2 mg/kg/day (on days 0, 2, 4, 6, 8), tacrolimus 1 mg/kg/day (daily, from days 0 to 9), and a single dose of anti-lymphocyte serum (10 mg) on day 10, soon after total body irradiation (300 cGy) and donor bone marrow (100 x 10(6) T-cell depleted cells) transplantation (BMT). Six weeks after BMT, chimeric animals received heterotopic heart transplants. RESULTS: Hematopoietic chimerism was 18.8 +/- 10.6% at day 30, and was stable (24 +/- 10%) at 1 year post-BMT; there was no graft versus host disease. Chimeric recipients (RT1.A(u)) permanently accepted (>360 days) donor-specific (RT1.A(a); n = 6) hearts, yet rapidly rejected (<9 days) third-party hearts (RT1.A(l); n = 5). Graft (heart) tolerant (>100 days) recipients accepted donor-specific secondary skin grafts (>200 days) while rejected the third-party skin grafts (<9 days). Lymphocytes of graft tolerant animals demonstrated hyporesponsiveness in mixed lymphocyte cultures in a donor-specific manner. Tolerant graft histology showed no obliterative arteriopathy or chronic rejection. CONCLUSIONS: The CTLA4-Ig based conditioning regimen with donor BMT produced mixed chimerism and induced donor- specific tolerance to cardiac allografts.

Abatacept↗

PubMed2006

Aortic valve bypass for aortic stenosis: imaging appearances on multidetector CT.

OBJECT: Aortic valve bypass is a technique used in high-risk patients with critical aortic stenosis that consists of placement of a conduit from the left ventricular apex to descending aorta. We describe the imaging appearances of this apicoaortic conduit on multidetector CT (MDCT). METHODS: Each patient underwent retrospective ECG-gated MDCT using a 16-detector-row scanner several days after placement of an apicoaortic conduit. All images were assessed by two radiologists who reviewed the appearance of the apicoaortic conduit and any post-operative complications. Follow-up studies were available for several patients. RESULTS: Twelve patients (9 men, 3 women, mean age - 78 years) underwent evaluation and the conduit was visible in each. The valve within the conduit was visible in ten (91%) of the 11 patients who received intravenous contrast material. Common findings were periconduit outpouching and hypoperfusion involving the left ventricle. Complications included pericardial hemorrhage, hemothorax and ventricular pseudoaneurysm. Mild to moderate increase in wall thinning was identified in the three patients who underwent follow-up imaging. CONCLUSION: Aortic valve bypass with an apicoaortic conduit appears to be a feasible alternative to aortic valve replacement in high-risk patients. MDCT is an excellent method to assess the imaging features of such conduits.

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PubMed2006

Off-pump versus on-pump coronary artery bypass grafting in consecutive patients: decision-making algorithm and outcomes.

BACKGROUND: Debate continues between on-pump or off-pump approach for coronary artery bypass grafting (CABG). We used off-pump coronary artery bypass grafting (OPCAB) as a tool within a decision-making algorithm driven by the patient-related factors of coronary anatomy and comorbidity. Our analysis presents this decision algorithm and describes outcomes using this approach. METHODS: From January 2000 to December 2003, 592 consecutive patients undergoing isolated CABG were assigned by one surgeon to a technique: on-pump CABG or OPCAB according to (1) anatomy and (2) predicted risk. Anatomic factors against OPCAB were target vessel size less than 1.25 mm, calcification, poor quality, intramyocardial location, and multiple stenoses. Given that OPCAB could be performed safely, patients in the moderate risk range, ie, those elderly with multiple comorbidities, were preferentially treated using OPCAB. RESULTS: The OPCAB group had higher predicted 30-day mortality compared with the on-pump CABG group, consistent with the protocol's intent. However, morbidity and mortality were similar between on-pump CABG and OPCAB. The OPCAB patients received the same number of internal mammary artery grafts but fewer distal grafts. Mortality and observed to expected ratios were favorable for both groups and below those The Society of Thoracic Surgeons' predicted for OPCAB. CONCLUSIONS: Matching surgical strategy to patient-related factors and needs resulted in excellent outcomes. Our data support the use of a protocol based on patient characteristics to drive the surgeon's choice between an on-pump CABG or OPCAB approach. As such, OPCAB can be viewed as a tool to be used by the surgeon developing a best practice in treating coronary artery disease.

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PubMed2006

Aortic valve bypass for the high-risk patient with aortic stenosis.

BACKGROUND: Interest in percutaneous therapy of heart valve disease has focused attention on the high-risk patient with aortic stenosis. Aortic valve bypass (apicoaortic conduit) surgery is the construction of a vascular graft containing a bioprosthetic valve from the apex of the left ventricle to the descending thoracic aorta. We have undertaken a programmatic effort to perform aortic valve bypass surgery as an alternative to conventional aortic valve replacement in selected high-risk patients, and now report our recent experience. METHODS: Between April 2003 and May 2005, 14 patients with aortic stenosis underwent aortic valve bypass surgery at two institutions. All patients selected for aortic valve bypass surgery were deemed to be at very high risk for conventional aortic valve replacement. These patients represented 14 (5.8%) of all 243 patients undergoing isolated aortic valve surgery during the same time period. Mean Society of Thoracic Surgeons predicted risk for operative mortality (11%) was between the 90th and 95th percentile. RESULTS: Twelve of 14 patients had previous cardiac surgery with patent bypass grafts. Average age was 78 years. Mean aortic valve area was 0.68 cm2. All operations were performed through a left thoracotomy on the beating heart (cross-clamp time, 0 minutes). Cardiopulmonary bypass was used for 6 patients (median cardiopulmonary bypass time, 15 minutes). There were 2 perioperative deaths. Median postoperative length of stay was 9 days. Two noncardiac late deaths occurred. Nine of 10 surviving patients are functional class I and are living independently. Early postoperative echocardiography confirms excellent aortic valve bypass function with preservation of ventricular ejection performance. CONCLUSIONS: Treatment of high-risk aortic stenosis patients with aortic valve bypass surgery is promising. Avoidance of sternotomy and cardiopulmonary bypass supports broader application to moderate-risk patients with aortic stenosis and as a control arm for studies of novel interventional therapies.

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PubMed2006

An unusual cause of pulmonary vein stenosis: a case report and review of the literature.

We describe the case of a patient with the Carney syndrome and several resections for recurrent left atrial myxomas who underwent autotransplantation of the heart with resection of the left and right atria and reconstruction of both atria with bovine pericardium. She subsequently presented with severe shortness of breath, ascites, and peripheral edema. She was found to have stenosis of all four pulmonary veins and severe pulmonary hypertension. We describe the echocardiographic findings and review the literature on assessment of acquired pulmonary vein stenosis.

Cardiac Surgical Procedures↗

PubMed2005

Endothelial injury and acquired aspirin resistance as promoters of regional thrombin formation and early vein graft failure after coronary artery bypass grafting.

OBJECTIVE: The predominant mechanism of early graft failure after coronary artery bypass grafting remains in doubt. Aspirin administered in the initial hours after coronary artery bypass grafting improves graft patency, implicating prostanoid synthesis in the pathogenesis. We hypothesized that synergy between endothelial disruption in the venous conduit and aspirin resistance would cause vein graft failure. METHODS: Aspirin resistance, defined by diagnostic findings on at least two of three separate assays, was serially assessed in 225 patients undergoing off-pump coronary artery bypass grafting. Endothelial cell integrity was determined in surplus segments obtained from 408 vein grafts. The deposition of intraluminal thrombin within the vein was determined by comparing serum F1.2 levels between the coronary sinus and the aorta after grafting. Intraoperative blood flow in the grafts was measured with transit-time technology, and patency was assessed with electrocardiographically gated multichannel computed tomographic coronary angiography on day 5. Aspirin was the sole antithrombotic agent used during the study. RESULTS: Thrombosed grafts (16/408) showed more endothelial cell loss at the time of grafting than did those grafts that remained patent (10.8% +/- 21.5% vs 51.4% +/- 39.1% integrity, P < .01). Aspirin resistance occurred in 67 patients (30%). Graft thrombosis was associated with aspirin resistance (P < .04) and reduced endothelial integrity (P < .01). These factors coexisted in 14 of 16 grafts that failed and were associated with elevated coronary sinus F1.2 levels. CONCLUSION: Aspirin resistance and relatively compromised venous endothelial cell integrity together marked patients whose vein grafts failed within days after off-pump coronary artery bypass grafting. These observations form a basis for identifying patients at risk and developing approaches to prevent vein injury or to selectively intervene in high-risk circumstances.

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PubMed2005

A novel approach to tricuspid valve replacement: the upside down stentless aortic bioprosthesis.

BACKGROUND: Tricuspid valve replacement (TVR) is a rarely needed operation. Choices between mechanical and biological prosthesis still generate controversy. We present our initial clinical experience with a stentless aortic root placed inverted in the tricuspid annulus. METHODS: Between August 2000 and September 2003, TVR for severe tricuspid insufficiency was performed in 8 patients. Indications were infective endocarditis (7) and iatrogenic damage (1). Mean age was 42.2 years old (20 to 58 years old). Five patients were male and 3 patients had a concomitant procedure (mitral valvuloplasty, coronary bypass grafting, and aortic valve replacement). A stentless aortic root, size 27 mm (n = 5) or 29 mm (n = 3) was placed inverted in the tricuspid position after the valsalva sinuses were scalloped. Interrupted 4-0 polypropylene sutures were used between the tricuspid valve annulus and the sewing ring. The struts equivalent on the stentless valve were anchored to the septal, anterior and posteroinferior wall of the right ventricle using 5-0 PTFE pledgeted sutures. RESULTS: Hospital survival was 100% and mean hospital stay was 12.5 days (3 to 18 days). Intraoperative and follow-up echocardiograms revealed no stenosis or insufficiency. Mean follow-up was 17.2 months (1-38 months). There were 3 late deaths due to continued IV drug use (n = 2) and end-stage renal failure (n = 1). CONCLUSIONS: This is a novel surgical alternative for a very high risk population. Potential advantages over current options include minimization of blood contact with nonbiological surfaces, preservation of annular motion, freedom from anticoagulation, and a theoretical lower rate of calcification.

Adult↗

PubMed2005

A multi-institutional experience with the CryoMaze procedure.

BACKGROUND: The Cox Maze III operation remains the gold standard for the surgical treatment of atrial fibrillation (AF). We report our experience using a flexible argon-powered metal cryoprobe for creation of the complete Cox-Maze III lesion set in patients with AF (the CryoMaze operation). METHODS: Beginning July 2002, 38 patients underwent the CryoMaze operation. Two patients had isolated CryoMaze procedures, whereas 36 patients had the CryoMaze performed in combination with coronary, valvular, or aortic surgery. All patients had electrocardiographic follow-up. Atrial fibrillation was continuous in 79%. Mean duration of AF before operation was 48 months. RESULTS: There were no complications related to the use of cryoenergy. There was 1 hospital death (2.6%) and no late deaths. At a mean follow-up of 12 months, 35 of 37 patients (95%) were in normal sinus rhythm. One patient required pacemaker implantation 3 months after surgery, and 1 patient refused follow-up. There have been no early or late thromboembolic events. CONCLUSIONS: The CryoMaze operation reliably cures atrial fibrillation at medium term follow-up, with rates identical to those reported for the classic Cox-Maze III operation.

Adult↗

PubMed2005

Surgical treatment of mitral valve endocarditis in North America.

BACKGROUND: Several single-institution series have suggested the feasibility and effectiveness of mitral valve repair for infective endocarditis (IE). METHODS: We examined 6627 patients with IE undergoing mitral valve surgery at 661 Society of Thoracic Surgeons-participating centers in 1994 to 2003. RESULTS: The diagnosis of IE was assigned to 5.8% (6,627 of 114,934) of patients having mitral valve surgery. The overall frequency of mitral valve repair for IE was 29.7% (1,965 of 6,627). Mitral valve repair was less frequently used for patients with active IE (423 of 2,654; 15.9%) than those with treated IE (1,459 of 3,570; 40.9%). Operative mortality was 3.7% (72 of 1,965) for mitral valve repair and 10.8% (502 of 4,662) for mitral valve replacement. Mortality rates were lower for patients with treated IE compared with active IE. After adjusting for multiple preoperative risk factors, mitral valve repair (odds ratio, 0.67; 95% confidence interval, 0.51 to 0.88) was associated with a significantly lower risk of death. Active (versus treated) IE (odds ratio, 2.12; 95% confidence interval, 1.68 to 2.68) and recent cerebrovascular accident (odds ratio, 1.71; 95% confidence interval, 1.28 to 2.31) were independent predictors of mortality. CONCLUSIONS: Mitral valve repair is less commonly applied for IE compared with other indications for mitral valve surgery. Patients with active IE were less likely to receive repair than those with treated IE. Mitral valve repair was associated with a lower risk of mortality. These results provide support for performing mitral valve repair when technically feasible in the setting of IE.

Aged↗

PubMed2004

Optimal timing of cardiac transplantation after ventricular assist device implantation.

OBJECTIVE: We sought to determine the influence of the interval from ventricular assist device implantation to cardiac transplantation on end-organ function and posttransplantation survival. METHODS: United Network for Organ Sharing data on 2692 heart transplantations performed in adult patients in the United States between October 1999 and March 2001 were reviewed. RESULTS: Seventeen percent (466) of adult heart transplant recipients were bridged to transplantation with a ventricular assist device. Almost half of patients with ventricular assist devices undergoing transplantation were upgraded to status 1A as a result of ventricular assist device-related complications occurring more than 30 days after ventricular assist device implantation. Creatinine and total bilirubin levels were less in patients undergoing transplantation after 2 to 4 weeks of mechanical support. One-year survival was higher in the nonventricular assist device than in the ventricular assist device group (85.7% vs 79.7%, P =.0004). Within the ventricular assist device group, survival was lower for patients undergoing transplantation within 2 weeks of ventricular assist device implantation compared with those undergoing transplantation later (74.2% vs 84.2 %, P =.03). One-year survival among patients supported with a ventricular assist device for more than 30 days without complications was 91.4%. Multivariate analysis demonstrated a significant independent effect of the time interval from ventricular assist device implantation to transplantation on posttransplantation mortality and suggested that a period of lowest risk might exist between 1 and 3 months after implantation. CONCLUSIONS: Survival after cardiac transplantation is influenced by the time interval from ventricular assist device insertion to transplantation. Survival is significantly lower when performed within 2 to 4 weeks of ventricular assist device implantation.

Adult↗

PubMed2003

Staged laparoscopic splenectomy and valve replacement in splenic abscess and infective endocarditis.

Splenic abscess is a rare clinical entity that is most commonly associated with infective endocarditis. Valve replacement in the setting of an unaddressed splenic abscess is associated with a high incidence of prosthetic valve infection and death. We describe 2 patients with infective endocarditis and splenic abscess treated by laparoscopic splenectomy followed by valve replacement.

Abscess↗