Epidemiology of Deep Sternal Wound Infection in Cardiac Surgery

Deep sternal infection has an incidence of 1.8% in the authors' practice. Improvements in surgical management using a staged approach with vacuum dressings have contributed to improved outcome, but mediastinitis still has a significant negative impact on long-term outcome. The most important patient-related independent risk factors for DSWI include obesity, diabetes, and aortic calcification. The main procedure-related independent risk factors identified were procedural complexity, CPB time, and re-exploration for bleeding. Future research efforts should focus on the identification of patients at risk, the development of preventive measurements, and the development of alternative therapies in high-risk patients.     

Physiologic basis for the surgical treatment of ischemic mitral regurgitation

Ischemic mitral regurgitation (MR) can complicate severe coronary artery disease and myocardial infarction. Ischemic MR results from left ventricular remodeling after myocardial infarction and can also accompany acute myocardial ischemia. The most common mechanism of ischemic MR is Carpentier's type IIIb dysfunction due to an apical and lateral displacement of papillary muscles leading to a tethering of the mitral leaflets. This apical tenting of the leaflets prevents the free margin from reaching the plane of the annulus, significantly reduces the surface of coaptation, and causes MR. Recent advances in imaging studies have led to a better understanding of the pathophysiology of this condition as well as to the development of innovative surgical approaches to treat this disease. Current research efforts have mainly focused on 2 directions: (1) percutaneous approaches to correct MR, and (2) surgical therapy to address the ventricular component of the disease. In this article, the authors define ischemic MR and review its pathophysiology, current management strategies, and future directions.     

ARTA: AT<Subscript>1</Subscript>-receptor blocker therapy in patients undergoing coronary artery bypass grafting

Background  Decline in renal and cognitive function may complicate early recovery after coronary-artery bypass grafting. AT₁-receptor antagonists have been demonstrated to be neuro- and renoprotective. Aim of ARTA, a prospective, double-blind, randomised and placebo controlled study, was to detect whether preoperative treatment with candesartan influences postoperative cognitive and renal function. Study protocol  One hundred and five patients eligible for coronary artery bypass graft surgery (65–85 years old, all suffering from hypertension and coronary artery disease, with stable kidney function) were randomized to candesartan (8 mg od) or placebo for between 8 and 11 days prior to surgery. Existing ACE-inhibitor/angiotensin receptor antagonist-therapy had to be stopped prior to the study. Validated cognitive function tests (trail making, Horn’s perfomance III und VI, divided attention and change of reaction, memory - immediate and delayed recall, digit span) were performed preoperatively, 1 week and 3 months after surgery. Renal function was assessed by creatinine clearance on the day before, 1 week and 3 months after surgery. Results  Eighty-seven patients (n = 43 Candesartan, n = 44 placebo) were included in the ITT-population for analysis. Drug treatment had no adverse effect on perioperative blood pressure. Only five patients experienced a period of hypotension during introduction of anaesthesia (Candesartan 1/44, placebo 4/44). One week as well as three months after surgery, there were no differences in relevant cognitive function parameters compared to the status prior to surgery, independent from treatment. Creatinine clearance showed a clear decrease one week after surgery with a minor further reduction observed 3 months after surgery, but there was no difference between Candesartan and placebo treated patients. Between both groups, there were no significant differences in the number of adverse events and number of patients with adverse events nor in the incidence of renal failure with consecutive dialysis and cerebral strokes (candesartan 2, placebo 5) and possibly drug related severe adverse events. Conclusion  This randomised placebo-controlled and prospective study in elderly patients does not support previous reports suggesting a substantial impairment of cognitive function after coronary artery bypass graft surgery. Preservation of cognitive and renal function was independent of pre-surgical administration of candesartan. Both centres contributed equally to the study.     

Contrast-enhanced cardiac MRI before coronary artery bypass surgery: impact of myocardial scar extent on bypass flow

The aim of the study was to relate the extent of myocardial late gadolinium enhancement (LGE) in cardiac MRI to intraoperative graft flow in patients undergoing coronary artery bypass graft (CABG) surgery. Thirty-three CAD patients underwent LGE MRI before surgery using an inversion-recovery GRE sequence (turboFLASH). Intraoperative graft flow in Doppler ultrasonography was compared with the scar extent in each coronary vessel territory. One hundred and fourteen grafts were established supplying 86 of the 99 vessel territories. A significant negative correlation was found between scar extent and graft flow (r = −0.4, p < 0.0001). Flow in grafts to territories with no or small subendocardial scar was significantly higher than in grafts to territories with broad nontransmural or transmural scar (75 ± 39 vs. 38 ± 26 cc min⁻¹; p < 0.0001). In summary, the extent of myocardial scar as defined by contrast-enhanced MRI predicts coronary bypass graft flow. Beyond the probability of functional recovery, preoperative MRI might add value to surgery planning by predicting midterm bypass graft patency.