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Biomedical subjects

Brian Buxton

Publications and source records attributed to Brian Buxton.

12 recordsLinked to original sources
PubMed2005

Arterial conduits update.

Arterial grafting for coronary artery disease has been practiced routinely at the Epworth Hospital for 20 years. Bilateral versus single internal thoracic artery grafts is associated with improved survival, which progressively increased over the 20 years of post-surgery. The average increase in survival was 15% at 20 years. The question of whether to use the radial artery or the saphenous vein graft as supplementary grafts remains unanswered. Current patency data suggest that there is a marginal advantage of radial artery over saphenous graft patency, particularly between 5 and 10 years after surgery. However, there appears to be improved patency of the saphenous vein when used as a coronary artery bypass with the advent of aspirin, lipid-lowering and anti-hypertensive therapy.

Blood Vessel Prosthesis Implantation↗
PubMed2004

Bench-to-bedside review: Inotropic drug therapy after adult cardiac surgery -- a systematic literature review.

Many adult patients require temporary inotropic support after cardiac surgery. We reviewed the literature systematically to establish, present and classify the evidence regarding choice of inotropic drugs. The available evidence, while limited in quality and scope, supports the following observations; although all beta-agonists can increase cardiac output, the best studied beta-agonist and the one with the most favourable side-effect profile appears to be dobutamine. Dobutamine and phosphodiesterase inhibitors (PDIs) are efficacious inotropic drugs for management of the low cardiac output syndrome. Dobutamine is associated with a greater incidence of tachycardia and tachyarrhythmias, whereas PDIs often require the administration of vasoconstrictors. Other catecholamines have no clear advantages over dobutamine. PDIs increase the likelihood of successful weaning from cardiopulmonary bypass as compared with placebo. There is insufficient evidence that inotropic drugs should be selected for their effects on regional perfusion. PDIs also increase flow through arterial grafts, reduce mean pulmonary artery pressure and improve right heart performance in pulmonary hypertension. Insufficient data exist to allow selection of a specific inotropic agent in preference over another in adult cardiac surgery patients. Multicentre randomized controlled trials focusing on clinical rather than physiological outcomes are needed.

Cardiac Output, Low↗
PubMed2004

Early and midterm results with the Ross procedure: a study of the first 31 cases.

Between 1994 and 2002, 31 patients underwent the Ross procedure by a single surgeon. The mean age was 42 years (24-61), 87% were male and 61% were in New York Heart Association (NYHA) class III-IV. Pure aortic stenosis (AS) was present in 32% of patients, pure aortic regurgitation (AR) in 22% and mixed disease in the rest. The aortic valve was bicuspid in 93.5% of the patients. Autograft implantation was by full root replacement in all cases. Concomitant cardiac surgical procedures were carried out in 10/31 (32%). All patients had at least annual clinical and echocardiographic follow-ups. There was one early death (3%). Overall patient survival was 92.7% at 1 year and 86.1% at 5 years. Twenty-eight (96.55%) were in NYHA class I. Echocardiographic follow-up revealed none to trivial AR in 24/29 (82.75%) and mild AR in 4/29 (13.7%). There was no autograft re-operation before 5 years. The mean gradient across the autograft was low (< 4 mm Hg). There were no incidences of endocarditis or thromboembolism. None of the patients required anticoagulation. Our early experience with the Ross procedure has shown good results in relation to early and midterm morbidity, mortality, autograft, and homograft function.

Adult↗
PubMed2003

Norepinephrine for hypotensive vasodilatation after cardiac surgery: impact on renal function.

OBJECTIVES: Norepinephrine use in patients after cardiac surgery is controversial because of the fear that norepinephrine might decrease kidney function through regional vasoconstriction. Accordingly, we studied the renal effects of norepinephrine use for hypotensive vasodilatation after cardiac surgery. DESIGN AND SETTING: Retrospective controlled study in the cardiothoracic ICU of tertiary hospital. PATIENTS. 100 cardiac surgery patients with post-operative hypotensive vasodilatation and 100 control cardiac surgery patients. INTERVENTION: Treatment of hypotension (MAP<70 mmHg) with continuous norepinephrine infusion. MEASUREMENTS AND RESULTS: We collected data on demographic and surgical characteristics, haemodynamics, serum creatinine and mortality. Just after surgery the norepinephrine group had a significantly higher mean central venous pressure, lower mean arterial pressure, and lower systemic vascular resistance index with a similarly elevated mean cardiac index. Despite norepinephrine administration at a mean peak dose of 7.3+/-6.4 micro g/min the mean post-operative change in creatinine was not different between two groups on days 0, 2 or 4 after surgery. CONCLUSIONS: Norepinephrine does not increase post-operative serum creatinine concentrations in patients with hypotensive vasodilatation after cardiac surgery. Concerns related to its potential adverse effects on the kidney function in this setting appear unjustified.

Aged↗
PubMed2003

Cardiac surgical audit Epworth Hospital 2002.

The cardiac surgical programme at Epworth Hospital has performed in excess of 13 000 open-heart surgical procedures between 1981 and 2003. During the audit period (2002) 411 patients underwent open-heart surgery. The 2002 Cardiac Surgical Audit confirms the very high standard of surgery. The goals for the future are to maintain the low complication rate and maintain an efficiency to reduce the financial burden on the hospital, the insurance companies and the health system.

Journal Article↗
PubMed2003

Mitral regurgitation: comparison between edge-to-edge repair and valve replacement.

Mitral regurgitation due to bileaflet prolapse and ischemic causes can be difficult to repair. Midterm experience of the Alfieri edge-to-edge repair as an alternative to valve replacement is reported. Twenty-six patients with severe mitral regurgitation underwent the Alfieri repair between January 1998 and December 2000 (group 1); 15 cases were due to bileaflet prolapse and 7 were of ischemic origin. During the same period, valve replacement was performed in 36 patients (group 2), 20 of whom had similar indications. Follow-up was complete to a mean of 15 months (range, 1-28 months). There was no early death in either group. During follow-up, there was no reoperation in group 1, while 2 patients in group 2 required reoperations due to prosthetic valve endocarditis. There were 4 major thromboembolic or bleeding events in group 2, and none in group 1. All patients in group 1 had trivial to mild mitral regurgitation on follow-up echocardiography. The mean mitral valve gradient was significantly higher in group 2 compared to group 1 (7.2 versus 3.2 mm Hg, p = 0.001). The edge-to-edge repair is associated with good early and midterm results. Long-term follow-up is required to evaluate the durability of this technique.

Aged↗
PubMed2002

Severe ischemic early liver injury after cardiac surgery.

BACKGROUND: The epidemiology, pathogenesis and prognosis of severe ischemic early liver injury (SIELI) after cardiac surgery are poorly understood. Accordingly, we studied patients whose alanine transaminase (ALT) concentration acutely increased above 500 IU/l in the immediate postoperative period and compared these patients to two control groups matched for preoperative and immediate postoperative characteristics. METHODS: We used a prospective database of 1,800 consecutive cardiac surgical cases to identify the study groups. Group I was made up of 20 patients with ALT levels above 500 IU/L in the acute postoperative stage (SIELI). Preoperative liver tests were normal in all these patients. Group II was obtained by identifying 20 control cases whose age, type of surgery, NYHA classification, and Parsonnet score matched Group I (preoperative controls). Group III was obtained by identifying 20 patients who developed postoperative acute renal failure and shock (ARF/shock; postoperative controls) but no enzyme evidence of hepatic injury. RESULTS: Acute renal failure, a low cardiac index (CI) state, and mortality were more common in SIELI and ARF/Shock patients compared with preoperative controls (all p values less than 0.01). Peak postoperative pulmonary artery occlusion (PAOP) and central venous (CVP) pressures were also higher in SIELI and ARF/Shock patients than controls (all p values less than 0.02). A higher dose of norepinephrine and milrinone were required to maintain blood pressure and cardiac output in SIELI and ARF/shock patients than preoperative controls (all p values less than 0.005). SIELI patients, however, differed from ARF/Shock patients in that they had a higher preoperative NYHA class and a greater incidence of hypertension and diabetes. Stepwise linear regression analysis identified a postoperative low CI and the presence of diabetes as the only predictors of peak ALT value (p less than 0.05). Multivariate logistic regression analysis identified female gender as being associated with a higher likelihood of SIELI (odds ratio: 6.13; 95% CI 1.08 to 34.82) CONCLUSIONS: SIELI after cardiac surgery carries a high mortality and is strongly associated with a low cardiac output and increased filling pressures, suggesting that liver ischemia induced by a combination of decreased perfusion and congestion is fundamental to its pathogenesis. A history of cardiac failure, diabetes, hypertension, and female gender may represent risk factors for its development and severity in the setting of a postoperative low cardiac output state.

Acute Kidney Injury↗