Biomedical subjects
Publications and source records attributed to S Kolvekar.
Saphenous leg veins are commonly used in coronary artery bypass grafting. Removal of the vein may cause oedema, erythema and tenderness in the leg. External support stockings are often used routinely to ease these common symptoms and prevent deep vein thrombosis.
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OBJECTIVE: Atrial fibrillation (AF) is a common complication after coronary artery bypass grafting (CABG) operations, occurring in 5 to 40% of cases. A number of studies have implicated atrial ischaemia in the genesis of this arrhythmia. The aim of this study was to examine the relationship between atrial coronary anatomy and the incidence of post operative atrial fibrillation. METHOD: To investigate a possible anatomical explanation to the onset of AF after CABG, 25 patients with documented AF after CABG were matched and compared to 25 patients which remained in sinus rhythm (SR). All coronary angiograms were reported blindly by a cardiac radiologist with reference to the blood supply of the sino-atrial (SA) node and atrio-ventricular (AV) node before and after surgery. RESULTS: Univariate analysis of risk factors did not identify any significant difference (Fisher exact test, P > 0.05) between the two groups in age, gender, left ventricular function, ischaemic time, number of vessels diseased or grafted, renal dysfunction and withdrawal of beta-blockade. However, significant disease in the SA nodal artery was present in 2 patients of the SR group when compared to 9 in the AF group. Significant disease of AV nodal artery was present in only 4 patients of the SR group when compared to 18 in the AF group. Comparison between the two groups showed a significantly increased incidence of SA or AV nodal artery disease in the AF group, (SA: P = 0.018, AV: P = 0.0001). Mean hospital stay was 8.1 days for the SR group and 9.1 days in the AF group (P = 0.175). CONCLUSION: Obstructive disease in the SA nodal and AV nodal arteries is more common in patients developing atrial fibrillation following coronary artery bypass surgery than those who remain in sinus rhythm. If the incidence of AF could be predicted by the anatomical distribution of arterial disease then targeting prophylaxis to this group may be possible.
OBJECTIVE: To define the clinical value of the signal averaged P wave (SAPW) and to compare it with the standard electrocardiogram (ECG), echocardiogram, and clinical assessment for the prediction of atrial fibrillation after coronary bypass grafting (CABG). DESIGN: Prospective validation cohort study. SETTING: Regional cardiothoracic centre. PATIENTS: 201 unselected patients undergoing first elective CABG were recruited over six months. Patients requiring concomitant valve surgery were excluded. MAIN OUTCOME MEASURES: Age, sex, cardiothoracic ratio, and cardioactive drugs were noted. P wave specific SAPW recordings, ECG, and M mode echocardiograms from which left atrial diameter was measured were performed within 24 hours of surgery. Filtered P wave duration (SAPWD), spatial velocity, and energy were calculated from the SAPW. From the ECG, lead II P wave duration, P terminal force in lead V1, total P wave duration, and isoelectric interval were measured. Patients had Holter monitoring for 48 hours postoperatively and daily ECGs until discharge. RESULTS: Two patients died (1%) and 10 were unsuitable for analysis (5%). Of the remaining 189, 51 (27%) had atrial fibrillation (AF) lasting > 1 hour at a mean of 2 (0.5 to 7) days after CABG. Of the variables examined, only SAPWD (AF group 148 (SD 12), v 142 (14) ms, P = 0.008) and male sex (AF group 96%, v 78%, P < 0.01) were significantly different. A prospectively defined SAPWD of > 141 ms predicted atrial fibrillation with positive and negative predictive accuracies of 34% and 83%. Logistic regression analysis identified both male sex and SAPWD as significant independent predictors of postoperative atrial fibrillation. CONCLUSIONS: Signal averaged P wave duration was a better predictor of atrial fibrillation after coronary bypass grafting than standard electrocardiographic or echocardiographic criteria. The predictive value of this test is such that it is likely to be useful in the design of prospective trials of prophylactic antiarrhythmic treatment but is of limited use using current techniques in the clinical management of individual patients.
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The sheep has been the standard laboratory animal for extracorporeal membrane oxygenation (ECMO) research for many years and has proven to be an invaluable and reliable model. However the coagulation system of the sheep is significantly different from humans. These differences make it difficult to investigate the coagulative and inflammatory response to ECMO in sheep. The pig has a very similar coagulation system to humans and therefore makes a more appropriate model. We describe a porcine model of prolonged (48 hours) closed chest venovenous (VV) ECMO that we developed to investigate the inflammatory and coagulative response to different ECMO tubing materials. This model could be used to investigate any aspect of venovenous ECMO.
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