M. Panagiotou

Enhanced tolerance of the rat myocardium to ischemia and reperfusion injury early after acute myocardial infarction

AbstractIt is now recognized that changes occurring during cardiac remodeling may influence the tolerance of the myocardium to ischemic stress. Therefore, the present study investigated the response of the post-infarcted heart to ischemia in an experimental model of ischemia and reperfusion injury and the possible underlying mechanisms. Acute myocardial infarction (AMI) was induced in Wistar male rats by ligating the left coronary artery (AMI, n = 13), while sham-operated rats were used as controls (SHAM, n = 11). At 2 weeks, cardiac dysfunction was observed in AMI, as indicated by the reduction of the left ventricular EF%. Isolated hearts were then subjected to 30 min of zero-flow global ischemia followed by 45 min of reperfusion. Ischemic contracture was significantly depressed in AMI hearts. Postischemic left ventricular end diastolic pressure (LVEDP45) in mmHg and LDH release in IU/g were markedly decreased; LVEDP45 was 52.1 (7.5) for AMI vs 96.6 (7.5),P < 0.05 and LDH release was 7.5 (1.0) in AMI vs 11.4 (0.56) in SHAM, P < 0.05. This response was associated with 2-fold increase in HSP70 expression in AMI hearts (noninfarcted segment), P < 0.05 vs SHAM and 1.7 fold increase in the expression of the phospho-HSP27, P < 0.05, while the expression of PKCε was shown to be 1.4-fold less in AMI, P < 0.05. In conclusion, the post-infarcted heart seems to be resistant to ischemiareperfusion injury and heat shock protein 70 and 27 may be involved in this response.

Complete aortic arch transection after a blunt chest trauma.

We present a picture from the emergency digital subtraction angiography of a 16-year old male patient who experienced a blunt chest trauma as a result of a car accident (Fig. 1). The aortic arch was completely transected with the adventitia and the periaortic tissue providing tamponade and preventing extravasation. The picture shows the tourniquet-like hematoma in the aortic arch, the compromise of ̄ow in the left-subclavian artery and an anomalous origin of the left common carotid artery from the innominate artery, a variation that lessens the value of the aortic arch concerning the brain perfusion. The patient was successfully operated on with a combination of median sternotomy and left anterior thoracotomy and had his aortic arch and part of his ascending aorta replaced with the aid of extracorporeal circulation. He tolerated the procedure very well. He awoke neurologically intact and was discharged from the hospital the 10th post-operative day. European Journal of Cardio-thoracic Surgery 19 (2001) 84

Effect of exogenous nitric oxide during cardiopulmonary bypass on lung postperfusion histology.

We tested the hypothesis that nitric oxide (NO) administered during cardiopulmonary bypass (CPB) would preserve platelets and prevent postperfusion lung changes. Ten anesthetized Yorkshire pigs were put on normothermic CPB (right atrium to aorta) with a roller pump and membrane oxygenator for 1 hour. In the study group (n = 5), NO was delivered in the oxygenators gas inflow line with a MiniNO system at 5–10 ppm throughout CPB. In controls (n = 5), NO was not used. Crystalloid solution and norepinephrine were used to maintain blood pressure ≥ 60 mm Hg. Fifteen minutes after CPB termination, all pigs were killed with intravenous potassium chloride and exsanguinated via the right atrium. Organ samples were put in formalin solution, processed in paraffin blocks, and stained with hematoxylin and eosin. We did not observe any thrombi in any perfusion system. There were no differences observed in platelet counts and aggregation ability to ADP and collagen, or in neutrophil counts between groups. Bleeding times were similar between groups before and after CPB. Also, there was no significant difference in factor XIIa and fibrinopeptide A levels between groups. Methemoglobin did not exceed normal levels. Lungs were devoid of neutrophils after perfusion in NO-treated pigs, whereas many neutrophils were present in the respiratory membrane of controls. Low-dose exogenous NO in the oxygenators gas intake has no demonstrable effect on platelet number or function, but prevents neutrophil adhesion to lungs with a possible beneficial effect on postperfusion pulmonary morbidity.

Distal embolization of a transcatheter valve in a valve complex: a bail-out surgical approach

Transcatheter aortic valve replacement has emerged as an alternative to surgical aortic valve replacement for high-risk and inoperable patients. Although transcatheter aortic valve replacement avoids the use of extracorporeal circulation and sternotomy, it is nonetheless associated with inherent complications. We aim to present an embolized valve-in-valve complex in the ascending aorta, which required emergency surgery with deep hypothermic circulatory arrest and proximal aortic cannulation.