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Biomedical subjects

R D Stanbridge

Publications and source records attributed to R D Stanbridge.

17 recordsLinked to original sources
PubMed2000

Persistent but reversible coronary microvascular dysfunction after bypass grafting.

The effect of coronary artery bypass grafting (CABG) on absolute myocardial blood flow (MBF) has not been investigated previously. MBF (ml. min(-1). g(-1)) was measured at rest and during hyperemia (0.56 mg/kg iv dipyridamole) using H(2)(15)O and positron emission tomography in eight patients with three-vessel disease before surgery and 1 and 6 mo after full revascularization. Baseline MBF was 0.87 +/- 0.12 preoperatively and 1.04 +/- 0.14 and 0.95 +/- 0.13 at 1 and 6 mo after CABG, respectively (P < 0.05, 6 mo vs. preoperatively). Hyperemic MBF was 1.36 +/- 0.28 preoperatively and increased to 1.98 +/- 0.50 and 2.45 +/- 0.64 at 1 and 6 mo after CABG, respectively (P < 0.01, 6 mo vs. preoperatively). Coronary vasodilator reserve (hyperemic/baseline MBF) increased from 1.59 +/- 0.40 preoperatively to 1.93 +/- 0.13 and 2.57 +/- 0.49 at 1 and 6 mo, respectively (P < 0.05, 6 mo vs. preoperatively). Minimal (dipyridamole) coronary resistance (mmHg. min. g(-1). ml(-1)) fell progressively from 59.37 +/- 14.56 before surgery to a nadir of 35. 76 +/- 10.12 at 6 mo after CABG (P < 0.01 vs. preoperatively). The results of the present study confirm that CABG improves coronary vasodilator reserve progressively as a result of reduction in minimal coronary resistance. These data suggest persistent microvascular dysfunction that recovers slowly after surgery.

Adult↗
PubMed2000

The effect of a 'fast-track' unit on the performance of a cardiothoracic department.

OBJECTIVE: The objective of this study was to describe the impact of a 'fast-track' unit, combined with a computerised system for information collection and analysis, on the clinical practice and finance of a cardiothoracic department over the first 12 month period of its application. METHODS: Within 12 months, starting December 1996, 642 major cardiothoracic cases were performed at the Cardiothoracic Department, St Mary's Hospital, London, after the establishment of a 3-bed 'fast-track' unit, which was supported by a computerised system for admission planning and a pre-admission clinic. The main outcome measures were operating numbers, financial income, patient recovery and operative mortality. RESULTS: The 'fast-track' unit resulted in an increase of the operating numbers (11.3% increase in major cardiac cases) and income (38%), as compared with the year before. Some 525 patients out of 642 (81.8%) were scheduled for the 'fast-track' unit and 492 (93.7%) were successfully 'fast-tracked'. Coronary artery bypass grafting operations had the lowest 'fast-track' failure and mortality rates. Re-do operations and complex coronary procedures presented a high 'fast-track' failure rate of approximately 20-25%. Low cardiac output, postoperative bleeding and respiratory problems were the most frequent causes for 'fast-track' failure. CONCLUSIONS: The development of a 'fast-track' unit, supported by a computerised system for information collection and analysis and a pre-admission clinic, has resulted in a substantial improvement of operating numbers and financial income, without adversely affecting the clinical results. This task demanded close collaboration between a dedicated list manager and a designated member of the medical team. Patient selection with appropriate 'fast-track,' criteria may improve further the efficiency of 'fast-track' units in the future.

Aged↗
PubMed1999

Technical adjuncts in beating heart surgery comparison of MIDCAB to off-pump sternotomy: a meta-analysis.

OBJECTIVES: The technical aspects of minimal invasive surgery are discussed, together with a comparison of off-pump MIDCAB with off-pump sternotomy, with special respect to outcomes of death, infarct and anastomoses. METHODS: Technical aspects of beating heart surgery are described under the headings: Trauma; Access; Stabilisation; Ischaemia; Haemostasis; Suturing; and Circulatory support. Data from papers and meetings on minimal invasive surgery were collated to September 1998 and correlated with the unit of origin. Percentage figures were back calculated to provide an actual number from which a new data base was obtained relevant to the reporting incidence. For statistical analysis a Chi squared test with Yates correction was used. RESULTS: Sixty-three centres reported 3304 cases of MIDCAB surgery (M) and 21 centres reported over 3060 cases of off-pump surgery through a sternotomy (S). There was no difference in early or late death rates between the two groups (1.6% M:2.2% S). There was a higher infarct rate with MIDCAB (2.9% M: 1.45% S; P < 0.03). The occlusion and stenosis rates for MIDCAB were 3.9 and 6.6% whilst for sternotomy off-pump they were 4.9 and 1.4%. The stenosis difference was significant at the P < 0.001 level. A combined occlusion and stenosis rate showed a higher incidence with MIDCAB (10.5%), than sternotomy 6.4% (P < 0.08). Four major series showed comparative data before and after stabiliser usage in MIDCABs. The stenosis rate was significantly reduced with stabilisation from 9.6 to 3.7% (P < 0.002) as was the combined occlusion and stenosis rate from 16 to 5.0% (P < 0.0001). In the total series there was no significant difference in length of stay (4.6 days), incidence of atrial fibrillation (9%), or between conversion to sternotomy(MIDCAB group) or to bypass (sternotomy group) (5%) between the two groups (M and S). Grafting the right coronary artery by MIDCAB produced worse results than for the left anterior descending artery (LAD). CONCLUSIONS: There is an important failure rate with beating heart surgery; stabilisers reduce this risk and are essential tools in both MIDCAB and beating heart surgery and encourages the further use of minimally invasive approaches.

Coronary Angiography↗
PubMed1997

Minimally invasive coronary revascularization through parasternal incisions without cardiopulmonary bypass.

BACKGROUND: We report the results of minimally invasive coronary revascularization without cardiopulmonary bypass through miniparasternal incisions. METHODS: This procedure was performed in 40 patients with disease in the left anterior descending, first diagonal, and right coronary arteries. After a 5- to 7-cm left vertical parasternal incision and removal of two costal cartilages, the left internal mammary artery was harvested up to the 2nd rib. The left anterior descending artery was occluded by means of two polydioxanone monofilament sutures. The anastomosis was performed with one 7-0 Prolene suture while the heart was beating. In 4 cases the left internal mammary artery was used as a sequential graft to the left anterior descending artery and the first diagonal artery. In 14 cases the right coronary artery was grafted with the right internal mammary artery through a right parasternal incision. Postoperatively, 95% of the patients underwent angiographic assessment of the anastomoses. RESULTS: We performed 52 anastomoses (34 to the left anterior descending artery, 4 to the first diagonal artery, and 14 to the right coronary artery). The mortality was 0% and the morbidity included postoperative bleeding (5%), acute renal failure (2.5%), atrial fibrillation (2.5%), and wound infection (5%). No patient had ventricular arrhythmias or circulatory problems during or after the operation. Two patients (5%) with right internal mammary artery-to-right coronary artery grafting had graft failure that required a redo operation. CONCLUSIONS: Small vertical parasternal incisions may be an alternative approach for single and multiple coronary revascularization, with a low incidence of intraoperative cardiac complications. The application of this approach to the right coronary artery, however, carries additional technical difficulties, and careful patient selection may be required to achieve optimal results.

Adult↗
PubMed1993

Disease of the left main coronary artery: early surgical results and their association with carotid artery stenosis.

OBJECTIVES: To review the results of surgical revascularisation for left main coronary artery stenosis and the associated vascular pathology that is responsible for cerebrovascular complication. PATIENTS: 60 patients (45 men, 15 women) (mean age 61.3 (39-79)) who underwent revascularisation for stenosis of the left main stem coronary artery (LMS) between January 1987 and August 1990 were compared with an age and sex matched control group of patients undergoing revascularisation for triple vessel disease during the same period. OUTCOME MEASURES: In-hospital morbidity and operative mortality. RESULTS: 24 patients in the LMS group presented with unstable angina. The left ventricular ejection fraction was less than 50% in 30 patients and less than 30% in nine. 17 patients (28%) had large vessel extracranial carotid artery disease and 10 patients had vascular disease of the lower limbs. In six patients atheromatous plaques were noted in the ascending aorta during surgery. There was no in-hospital mortality. In-hospital morbidity included neurological deficits in five (8.3%), arrhythmias in seven (11.6%), and pulmonary complications in six (10%) patients. The incidence of carotid artery disease in the LMS group was significantly higher (p = 0.04). Atheromatous plaque in the ascending aorta and postoperative neurological complications were more common patients with LMS. CONCLUSIONS: The incidence of carotid artery disease was higher and postoperative cerebrovascular complications were more common in patients who had coronary artery revascularisation for stenosis of the left main stem coronary artery. The early surgical results were excellent. These findings suggest that for optimum perioperative management patients with stenosis of the left main coronary artery should be screened for carotid artery disease before bypass surgery.

Adult↗
PubMed1993

Comparison of measured and computed epicardial potentials from a patient-specific inverse model.

This study reports the first direct comparison of measured and computed epicardial potentials in which the specific anatomy of a test subject has been used to calculate the inverse electrocardiographic model. It is now feasible to obtain low-noise body surface potential maps and to incorporate accurate anatomic data into inverse procedures for the purpose of computing epicardial potential distributions. The direct verification of computed human epicardial distributions remains an important goal. The experiment reported here obtained direct measurements from six transcutaneous pacing wires that were attached to points on the epicardial surface of the human heart in an intact subject. From the same subject, a magnetic resonance scan was used to produce a specific thoracic model consisting of 5-mm cubes. The forward model uses the finite difference method to compute a forward transfer matrix that relates each of 26 epicardial regions to body surface measurements. The inverse computation was performed by zero-order Tikhonov regularization. Body surface potentials were used in the inverse procedure to compute epicardial potentials, which were then compared with direct epicardial measurements. The computed epicardial potentials were compared to the measured ones by correlation, which gave an amplitude-independent measure of similarity. Amplitude differences and time delays in computed potentials were observed, but the morphologic trend was generally well recovered. The results obtained indicate the sensitivity of the inverse model to a number of factors. The robustness of computed epicardial distributions to errors in assumed lung conductivity is shown. Results from a nonpatient-specific, but realistic, torso model are presented.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Pacing, Artificial↗
PubMed1992

Primary pericardial mesothelioma presenting as tuberculous pericarditis.

Ante-mortem diagnosis of primary pericardial mesothelioma is very rare. We report a case which presented clinically as tuberculous constrictive pericarditis. The patient underwent pericardial resection with an immediate haemodynamic benefit, although the malignant process progressed, and he died 14 weeks later.

Adult↗
PubMed1986

Plasma fibronectin and complement activation in coronary bypass surgery.

In patients with severe sepsis, plasma fibronectin concentrations are reduced and complement is activated. It is not known whether complement activation interferes with plasma fibronectin. Cardiopulmonary bypass is known to activate complement. We have therefore used this operation to study the effect of complement activation on plasma fibronectin in the absence of sepsis. After 15 min of bypass the percentage changes of plasma fibronectin and haematocrit were similar (65.9 +/- s.e.m. 4.8 and 67.0 per cent +/- s.e.m. 2.3, respectively), but the changes in C3 and C5 (58.4 +/- s.e.m. 4.8 per cent and 52.5 per cent +/- s.e.m. 2.1) were significantly greater than those of the haematocrit, indicating complement consumption. During the first 60 min of bypass there was a significant increase in the neutrophil count which is compatible with complement activation. It is unlikely that complement activation alone, in the absence of sepsis, contributes to the reduction of plasma fibronectin concentrations.

Adult↗
PubMed1986

Comparison of epicardial and body surface ECG potentials in man.

Simultaneously measured epicardial electrograms and body surface electrocardiograms in human subjects were compared. Unipolar electrograms were recorded from up to three epicardial sites in each of 21 patients one week after aortocoronary bypass surgery. Simultaneously, electrocardiograms were recorded from 37 body surface electrodes. The epicardial electrograms from ventricular sites correlated well during the QRS complex with body surface electrocardiograms at geometrically similar positions. In particular, most posterior epicardial sites correlated best with posterior body surface regions, contrary to model predictions. P waves recorded from the right atrial surface showed a sharp negative deflection not evident in body surface P waves. A large intersubject variation was evident when the magnitude of epicardial potentials was compared with the body surface potentials. The findings are relevant to the interpretation of surface maps, the estimation of epicardial potentials from surface maps, and the positioning of body surface electrodes.

Electrocardiography↗