Background-Brief periods of ischemia performed just at the time of reperfusion can reduce infarct size, a phenomenon called "postconditioning." After reflow, opening of the mitochondrial permeability transition pore (mPTP) has been involved in lethal reperfusion injury. We hypothesized that postconditioning may modulate mPTP opening. Methods and Results-Anesthetized open-chest rabbits underwent 30 minutes of ischemia and 4 hours of reperfusion.Control hearts underwent no additional intervention. Postconditioning consisted of 4 episodes of 1 minute of coronary occlusion and 1 minute of reperfusion performed after 1 minute of reflow after the prolonged ischemia. Preconditioning consisted of 5 minutes of ischemia and 5 minutes of reperfusion before the 30-minute ischemia. An additional group of rabbits received 5 mg/kg IV of NIM811, a specific inhibitor of the mPTP, 1 minute before reperfusion. Infarct size was assessed by triphenyltetrazolium staining. Mitochondria were isolated from the risk region myocardium, and Ca 2ϩ -induced mPTP opening was assessed by use of a potentiometric method. Postconditioning, preconditioning, and NIM811 significantly limited infarct size, which averaged 29Ϯ4%, 18Ϯ4%, and 20Ϯ4% of the risk region, respectively, versus 61Ϯ6% in controls (PՅ0.001 versus control). The Ca 2ϩ load required to open the mPTP averaged 41Ϯ4, 47Ϯ5, and 67Ϯ9 mol/L CaCl 2 per mg of mitochondrial proteins in postconditioning, preconditioning, and NIM811, respectively, significantly higher than the value of 16Ϯ4 mol/L per mg in controls (PՅ0.05). Conclusions-Postconditioning

Coronary patterns with intramural arteries remain associated with high coronary mortality and morbidity following neonatal ASO, even in the current era. The association of slit-like deformation of the ostium, stenosis of the intramural course and abnormal angle of take-off might explain the difficulty in coronary transfer. The technique of coronary transfer should be individually adapted to each anatomical situation. The place of patch ostioplasty of the intramural artery remains to be determined.

(1) Following ASO, coronary lesions are not uncommon and they are progressive. Routine and sequential coronary evaluation is necessary. (2) Coronary revascularization can be achieved using coronary angioplasty in most cases. Mammary bypass may be used in selected circumstances. Normal myocardial perfusion is restored in most patients.

Angulated Gothic aortic arch is associated with increased systolic wave reflection, as well as increased central aortic stiffness and left ventricular mass index. These findings explain (at least in part) the association between this pattern of arch geometry and late hypertension at rest and on exercise in subjects after coarctation repair.

Thus detailed multiplanar computed tomographic scanning can elucidate the mechanisms of late coronary complications after the ASO. Understanding these aspects could help to improve surgical technique to minimize the risk of late coronary obstructions.

The arterial switch operation has become the treatment of choice for neonates with transposition of the great arteries. Currently, the early mortality rate is low as well as the need for early reoperation because of surgical failures; in our experience with 803 neonates, these risks were 3.8% and 1.5%, respectively. The late outcome in terms of survival and functional status is excellent. However, surgical repair is far from anatomical and potential late defects were identified as soon as this procedure was introduced: obstruction of the neo-pulmonary outflow tract, development of obstructions of the reimplanted coronary arteries, dysfunction of the neo-aortic valve, and progressive left ventricular dysfunction. Actually, late reoperations are required in 5-10% of patients (4.5% in our experience with a mean follow-up of 5.8 years). The more frequent indications for reoperation are coronary lesions and right ventricular outflow tract obstructions. Coronary obstructions are, in most cases, detected in patients without any clinical or echocardiographic evidence of myocardial ischaemia. Coronary lesions are progressive and repeated coronary evaluation at regular intervals is necessary. Reoperation is indicated when myocardial ischaemia, at rest or under stress, is demonstrated at myocardial imaging. Satisfactory results can be achieved by surgical coronary patch angioplasty; in selected cases, mammary bypass may be necessary. Right ventricular outflow tract obstruction is related either to inadequate growth of the pulmonary anastomotic site, or to inadequate growth of the whole new right ventricular outflow tract in patients with associated aortic arch obstruction. Reoperation is indicated when significant obstruction (gradient >50 mmHg) is detected at routine echo-Doppler evaluation. Although neo-aortic root dilation and minimal aortic valve insufficiency are common, reoperation for severe neo-aortic valve dysfunction is, to date, very rarely necessary. Whether this will remain the case in the decades to come requires further evaluation. Left ventricular function is maintained in the vast majority of patients. Reoperation may be indicated in some patients for other reasons: mitral valve malformation, tracheo-bronchial compression or pulmonary hypertension.

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Halothane, isoflurane and desflurane induced pharmacological preconditioning, whereas sevoflurane had no significant effect. In this preparation, desflurane was the most effective agent at preconditioning the myocardium against ischaemia.