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.     

Effects of exogenous surfactant on the non‐heart‐beating donor lung graft in experimental lung transplantation – a stereological study

The use of non‐heart‐beating donor (NHBD) lungs may help to overcome the shortage of lung grafts in clinical lung transplantation, but warm ischaemia and ischaemia/reperfusion injury (I/R injury) resulting in primary graft dysfunction represent a considerable threat. Thus, better strategies for optimized preservation of lung grafts are urgently needed. Surfactant dysfunction has been shown to contribute to I/R injury, and surfactant replacement therapy is effective in enhancing lung function and structural integrity in related rat models. In the present study we hypothesize that surfactant replacement therapy reduces oedema formation in a pig model of NHBD lung transplantation. Oedema formation was quantified with (SF) and without (non‐SF) surfactant replacement therapy in interstitial and alveolar compartments by means of design‐based stereology in NHBD lungs 7 h after cardiac arrest, reperfusion and transplantation. A sham‐operated group served as control. In both NHBD groups, nearly all animals died within the first hours after transplantation due to right heart failure. Both SF and non‐SF developed an interstitial oedema of similar degree, as shown by an increase in septal wall volume and arithmetic mean thickness as well as an increase in the volume of peribron‐chovascular connective tissue. Regarding intra‐alveolar oedema, no statistically significant difference could be found between SF and non‐SF. In conclusion, surfactant replacement therapy cannot prevent poor outcome after prolonged warm ischaemia of 7 h in this model. While the beneficial effects of surfactant replacement therapy have been observed in several experimental and clinical studies related to heart‐beating donor lungs and cold ischaemia, it is unlikely that surfactant replacement therapy will overcome the shortage of organs in the context of prolonged warm ischaemia, for example, 7 h. Moreover, our data demonstrate that right heart function and dysfunctions of the pulmonary vascular bed are limiting factors that need to be addressed in NHBD.     

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.     

Kinetic of procalcitonin in the early postoperative course following heart transplantation

Abstract   Background: It was the aim of the study to determine the kinetics of procalcitonin (PCT) levels following heart transplantation (HTx) and to investigate the prognostic suitability of postoperative changes in PCT levels for patients' outcome. Methods: 52 adult heart transplant recipients were divided into two groups according to their in-hospital postoperative outcome retrospectively. Group A (eventful ± nonsurvivors) of 24 patients (21 males, three females, mean age 54.5 ± 10.1 years) was compared with Group B (uneventful) of 28 patients (22 males, six females, mean age 53.6 ± 8.1 years). Results: Serum PCT levels were measured before and daily after operation until day seven. Demographic data, operative data, and clinical endpoints (mortality, infection, severe complication) were analyzed. Mean PCT levels immediately before HTx were <0.3 ng/mL in both groups, respectively. PCT increased with maximum concentrations on the second post-operative day (Group A: 54.6 ± 44.3 ng/mL; Group B: 9.1 ± 9.3 ng/mL). After day two the levels decreased to 7.8 ± 8.8 ng/mL in Group A and 0.6 ± 0.8 ng/mL in Group B on day seven. Postoperative PCT was increased in nonsurvivors compared to survivors in Group A (81.6 ± 58.7 ng/mL vs 44.7 ± 19.8 ng/ml; p < 0.05). Conclusions: PCT levels have been consistently low (<10 ng/mL) in patients with an uneventful course, but more frequently increased in patients with postoperative complications and even associated with an increased mortality early postoperatively when values exceed 80 ng/mL. As a clinical consequence, PCT levels in the first few days following cardiac transplantation can help to identify patients at risk, when concentrations exceed the "normal" posttransplant range.     

Giant transit thrombus—From right to left

Pulmonary embolism can be associated with paradox embolism requiring immediate surgical therapy regardless of hemodynamic status. Here we present images illustrating a giant transit thrombus as a concomitant finding in a patient with pulmonary artery embolism.     

Intermittent antegrade warm myocardial protection compared to intermittent cold blood cardioplegia in elective coronary surgery--do we have to change?

OBJECTIVE: Intermittent antegrade warm blood cardioplegia (IAWBC) is a simple and cost-effective method of myocardial preservation. However, there are only few prospective trials comparing this type of cardioplegia to established cardioplegic strategies in elective on-pump coronary surgery with respect to myocardial protection and outcome. METHODS: In a prospective, randomized trial IAWBC (33 degrees C) (n=100) was compared to intermittent antegrade cold (4 degrees C) blood cardioplegia (n=100), regarding clinical outcome and myocardial protection using cardiac troponin-I (cTNI) and creatine kinase MB isoenzyme (CK-MB) measurements to assess ischemia. RESULTS: Preoperative parameters were comparable in both groups. Results demonstrated no differences in-between the groups regarding mortality (2.0% both), incidence of perioperative myocardial infarction (2 versus 3%), need for intra-aortic balloon pump (3 versus 4%), length of ICU stay (2.0+/-2.5 versus 2.1+/-3.0 days) and incidence of postoperative atrial fibrillation (41 versus 34%). However, the necessity of defibrillation after cardiac arrest (18 versus 43%, P<0.001) was significantly less frequent and of lower intensity (3.4+/-10.8 versus 10.8+/-20.6 J, P<0.001) in the IAWBC-group. Postoperatively the ischemia markers were significantly lower in the IAWBC-group, cTNI within the first 72 h (from P<0.001 to P=0.013) and even CK-MB within the first 24 h (from P=0.004 to P<0.011). CONCLUSION: IAWBC is a safe and simple method in elective on-pump coronary artery bypass surgery. Significantly lower ischemic markers suggest an improved myocardial protection compared to cold blood cardioplegia in these patients.