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Atrioventricular interval optimisation is important in patients with dual-chamber pacing, especially with heart failure. In patients with CHD, especially in those with Fontan circulation, the systemic atrial contraction is supposed to be more important than in patients without structural heart disease.
We retrospectively evaluated two patients after Fontan procedure with dual-chamber pacemaker with a unique setting of optimal sensed atrioventricular interval.
The optimal sensed atrioventricular interval determined by echocardiogram was extremely short sensed atrioventricular interval at 25 and 30 ms in both cases; however, the actual P wave and ventricular pacing interval showed 180 and 140 ms, respectively. In both cases, the atrial epicardial leads were implanted on the opposite site of the origin of their own atrial rhythm. The time differences between sensed atrioventricular interval and actual P wave and ventricular pacing interval occurred because of the site of the epicardial atrial pacing leads and the intra-atrial conduction delay.
We need to consider the origin of the atrial rhythm, the site of the epicardial atrial lead, and the atrial conduction delay by using electrocardiogram and X-ray when we set the optimal sensed atrioventricular interval in complicated CHD.
The peri-operative mortality of the arterial switch operation in neonates with transposition of the great arteries is considerably low; however, long-term outcomes of translocated coronary arteries still remain one of the most crucial issues.
Methods and results
A total of 110 neonates with transposition of the great arteries after arterial switch operation were evaluated; three (2.7%) late deaths occurred. The remaining 107 patients except for one underwent follow-up angiography. Angiography showed coronary artery stenosis in nine (8.4%), with right coronary artery lesions in two and left main trunk lesions in seven. In two patients, right coronary artery stenosis regressed during follow-up. In left main trunk lesions, the severity of stenosis improved in four, did not change in one, and progressed to total occlusion in two patients. In children with coronary artery stenosis, myocardial scintigraphy showed perfusion defects in five out of six (83%) with left main trunk with ⩾75% stenosis and in four out of four with left main trunk stenosis ⩾90%. In contrast, patients whose coronary artery stenosis disappeared during follow-up had no perfusion defects on scintigraphy.
Regression of ostial stenosis of the transplanted coronary artery on angiogram was observed. The stenosis regressed over time in six patients; two coronary arteries with 99% stenosis and delayed angiographic enhancement of the distal coronary artery resulted in total occlusion within 1 year after the arterial switch operation. Combination of angiography and myocardial scintigraphy could be useful to differentiate deceptive stenosis from progressive stenosis.
We analyzed retrospectively the relationship between coagulation profile, and either hepatic function or hemodynamics, in patients who had undergone a Fontan-type procedure, comparing them, first, with a control group of 12 patients without significant hemodynamic abnormality, and, second, with a group of 14 patients who had not undergone a Fontan procedure, but whose mean right atrial pressure exceeded 8 mmHg. Follow-up catheterization had been performed in all 30 patients submitted to the Fontan-type operation. Prothrombin time, and factor XIII, were significantly lower in those who had undergone the Fontan procedure than in the other groups. Those submitted to the Fontan operation also had lower levels of protein C than controls, and their levels of plasminogen were lower than the patients with high right atrial pressure. Both aspartate aminotransferase and alanine aminotransferase were higher in those undergoing the Fontan procedure than in the other groups, while gamma-glutamyltranspeptidase in these patients was higher than in the control group. Mean right atrial pressure was highest in those under-going the Fontan procedure, while cardiac index was lowest. Prothrombin time was correlated to some extent with aspartate aminotransferase, mean right atrial pressure, and cardiac index. Protein C correlated with both aspartate aminotransferase and mean right atrial pressure, while factor XIII correlated with alanine aminotransferase, mean right atrial pressure, and cardiac index. Aspartate aminotransferase, alanine aminotransferase, and gamma-glutamyltranspeptidase, parameters of hepatic function, correlated significantly with mean right atrial pressure. In those who had undergone the Fontan procedure, decreased synthesis of pro-and anti-coagulant factors is a risk factor for both thrombosis and bleeding. Abnormal hemodynamics, in the absence of a right sided pumping chamber, may predispose to subclinical hepatic dysfunction, leading to selective disturbances of protein synthesis.
The Fontan circuit is characterized by a pulmonary circulation dependent on central venous pressure in the absence of a subpulmonary ventricle. Patients with this circulation usually exhibit a low cardiac output. In addition to their abnormal cardiac state, recent studies have demonstrated impaired cardiac autonomic nervous activity, elevated neurohormonal factors, and impaired endothelial function, findings also encountered in adults with chronic heart failure. One major component of these impairments is the abnormal cardiorespiratory response during exercise. Despite some pathophysiologic similarities to adults with cardiac disease, those with the Fontan circulation usually have a congenitally malformed heart underscoring abnormal haemodynamics, with further compromise from multiple surgical procedures. It differs in many aspects from the situation in the adults with impaired systolic ventricular function in the setting of chronic cardiac failure. In this review, I will focus on the cardiorespiratory response during exercise, seeking to clarify the characteristics in these particular patients with the Fontan circulation.
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