Gertie C. M. Beaufort-Krol

Possible bradycardic mode of death and successful pacemaker treatment in a large family with features of long QT syndrome type 3 and Brugada syndrome

Pacemaker Treatment in LQT3 and Brugada Syndrome. Introduction: We recently identified a novel mutation of SCN5A (1795insD) in a large family with features of both long QT syndrome type 3 and the Brugada syndrome. The purpose of this study was to detail the clinical features and efficacy of pacemaker therapy in preventing sudden death in this family.

Comparison of longevity, pacing, and sensing characteristics of steroid-eluting epicardial versus conventional endocardial pacing leads in children

OBJECTIVE Because of either cardiac anatomy or small size, pacing in children often occurs by means of epicardial leads. The disadvantage of epicardial leads is the shorter longevity of these leads compared with endocardial leads. During short-term follow-up, improved stimulation thresholds were found for the newer steroid-eluting epicardial leads. The longevity of these leads may be better than that of conventional epicardial leads. An improved longevity of epicardial leads may influence the choice to either epicardial or endocardial pacing in children. METHODS We studied the longevity and the pacing and sensing characteristics of 33 steroid-eluting epicardial pacing leads (group I, 15 atrial, 18 ventricular) implanted between November 1991 and October 1996 in 20 children with a mean age of 7.6 +/- 6.5 years (mean +/- SD), and 29 endocardial pacing leads (group II, 15 atrial, 14 ventricular) implanted during the same period in 21 children with a mean age of 11.7 +/- 4.7 years. RESULTS The mean follow-up in group I was 2.9 +/- 1.6 years and in group II 3.1 +/- 1.7 years (P =.61). The 2-year survival of the leads in group I was 91% +/- 5% and in group II 86% +/- 7% (P =.97). Lead failure occurred in both groups in 4 leads (P =.85). Chronic stimulation and sensing thresholds were similar. CONCLUSIONS Steroid-eluting epicardial leads have the same longevity as the conventional endocardial leads. Pacing and sensing thresholds were similar and did not change during follow-up. Therefore steroid-eluting epicardial pacing leads are a good alternative for endocardial leads in small children and in children with congenital heart disease.

Perinatal changes in myocardial metabolism in lambs

BACKGROUND Lactate accounts for a third of myocardial oxygen consumption before and in the first 2 weeks after birth. It is unknown how the remainder of myocardial oxygen is consumed. Glucose is thought to be important before birth, whereas long-chain fatty acids (LC-FA) are the prime substrate for the adult. However, the ability of the myocardium of the newborn to use LC-FA has been doubted. METHODS AND RESULTS We measured the myocardial metabolism of glucose and LC-FA with [U-(13)C]glucose and [1-(13)C]palmitate in chronically instrumented fetal and newborn lambs. In fetal lambs, myocardial oxidation of glucose was high and that of LC-FA was low. Glucose and LC-FA accounted for 48+/-4% and 2+/-2% of myocardial oxygen consumption, respectively. In newborn lambs, oxidation of glucose decreased, whereas oxidation of LC-FA increased. Glucose and LC-FA accounted for 12+/-3% and 83+/-19% of myocardial oxygen consumption. To test whether near-term fetal lambs could use LC-FA, we increased the supply of LC-FA with a fat infusion. In fetal lambs during fat infusion, the oxidation of LC-FA increased 15-fold. Although the oxidation of LC-FA was still lower than in newborn lambs, the contribution to myocardial oxygen consumption (70+/-13%) was the same as in newborn lambs. CONCLUSIONS These data show that glucose and lactate account for the majority of myocardial oxygen consumption in fetal lambs, whereas in newborn lambs, LC-FA and lactate account for the majority of myocardial oxygen consumption. Moreover, we showed that the fetal myocardium can use LC-FA as an energy substrate.

Sotalol for atrial tachycardias after surgery for congenital heart disease

Atrial tachycardias, in particular atrial flutter after surgery for congenital heart disease, is associated with a high mortality. Treatment with various antiarrhythmic drugs and/or antitachycardia pacemakers is not very successful. Sotalol, a Class III drug, has shown to be a promising drug in adults with atrial tachycardias. However, the experience with sotalol in children after surgery for congenital heart disease is limited. Therefore, we describe our results here. Between December 1990 and February 1997, 26 children with atrial tachycardias, most of them with atrial flutter or fibrillation (n = 20), after surgery for congenital heart disease were treated with sotalol orally. The age of the children at the start of treatment was 7.5 ± 5.8 years (mean ± SD). The time interval between surgery and the start of atrial tachycardia ranged from 1 day to 14.3 years (3.8 ± 3.8 years). Conversion to sinus rhythm was achieved in 16 out of 22 hemodynamically stable children with a dosage of 4.0 ±1.6 mg/kg per day. The six children without sinus rhythm on sotalol and four hemodynamically unstable patients were treated prophylactically with sotalol after DC cardioversion for their tachycardias. Two children complained of mild transient fatigue. Heart rate decreased during therapy (95 ± 33 vs 81 ± 21 beats/min; P = 0.01). QTc‐intervals did not change. Proarrhythmias such as torsades de pointes were not encountered. Two children with a preexis‐tent sick sinus syndrome showed aggravation of bradycardia and needed pacemaker implantation. The percentage of children with a recurrence‐free interval of 1 and 2 years was 96% and 81 %, respectively, for all atrial tachycardias, and 92% and 66% for atrial flutter. The recurrences of atrial tachycardias during the follow‐up period, which ranged from 0.1‐6.1 years (2.5 ± 1.8 years) could be treated with only an increase of the dosage of sotalol in all but one patient. We conclude that sotalol is an effective drug for the treatment and prevention of atrial tachycardia in children afler surgery for congenital heart disease.

Ventricular Fibrillation Without Overt Cardiomyopathy as First Presentation of Organic Cation Transporter 2‐Deficiency in Adolescence

This case report describes ventricular fibrillation without overt cardiomyopathy as the presenting symptom of primary carnitine deficiency due to organic cation transporter 2 (OCTN2)‐deficiency in a 15‐year‐old girl. Normally this disease presents early in life with hypoketotic hypoglycemia, muscle weakness, and/or cardiomyopathy. The patient fully recovered after carnitine suppletion. Recognition of this disease is important because its treatment is easy and effective. (PACE 2004; 27:675–676)

Effectiveness of Sotalol for Atrial Flutter in Children After Surgery for Congenital Heart Disease

This study describes the efficacy of oral sotalol in the treatment and prevention of atrial flutter in children after surgery for congenital heart disease. In 11 of 13 children (85%), conversion to sinus rhythm was achieved, and in 8 of 11 within 24 hours.

AORTOPULMONARY WINDOW ASSOCIATED WITH AN ANOMALOUS ORIGIN OF THE RIGHT CORONARY-ARTERY

Abstract We report a case of a large aortopulmonary window associated with an anomalous origin of the right coronary artery from the pulmonary trunk and discuss the etiology of this rare anomaly.

Increased myocardial lactate oxidation in lambs with aortopulmonary shunts at rest and during exercise

Free fatty acids are the major fuels for the myocardium, but during a higher load carbohydrates are preferred. Previously, we demonstrated that myocardial net lactate uptake was higher in lambs with aortopulmonary shunts than in control lambs. To determine whether this was caused by an increased lactate uptake and oxidation or by a decreased lactate release, we studied myocardial lactate and glucose metabolism with 13C-labeled substrates in 36 lambs in a fasting, conscious state. The lambs were assigned to two groups: a resting group consisting of 8 shunt and 9 control lambs, and an exercise group (50% of peak O2 consumption) consisting of 9 shunt and 10 control lambs. Myocardial lactate oxidation was higher in shunt than in control lambs (mean +/- SE, rest: 10.33 +/- 2.61 vs. 0. 17 +/- 0.82, exercise: 38.05 +/- 8.87 vs. 16.89 +/- 4.78 micromol. min-1. 100 g-1; P < 0.05). There was no difference in myocardial lactate release between shunt and control lambs. Oxidation of exogenous glucose, which was approximately zero at rest, increased during exercise in shunt and control lambs. The contribution of glucose and lactate to myocardial oxidative metabolism increased during exercise compared with at rest in both shunt and control lambs. We conclude that myocardial lactate oxidation is higher in shunt than in control lambs, both at rest and during exercise, and that the contribution of carbohydrates in myocardial oxidative metabolism in shunt lambs is higher than in control lambs. Thus it appears that this higher contribution of carbohydrates occurs not only in the case of pressure-overloaded hearts but also in myocardial hypertrophy due to volume overloading.Free fatty acids are the major fuels for the myocardium, but during a higher load carbohydrates are preferred. Previously, we demonstrated that myocardial net lactate uptake was higher in lambs with aortopulmonary shunts than in control lambs. To determine whether this was caused by an increased lactate uptake and oxidation or by a decreased lactate release, we studied myocardial lactate and glucose metabolism with13C-labeled substrates in 36 lambs in a fasting, conscious state. The lambs were assigned to two groups: a resting group consisting of 8 shunt and 9 control lambs, and an exercise group (50% of peak O2consumption) consisting of 9 shunt and 10 control lambs. Myocardial lactate oxidation was higher in shunt than in control lambs (mean ± SE, rest: 10.33 ± 2.61 vs. 0.17 ± 0.82, exercise: 38.05 ± 8.87 vs. 16.89 ± 4.78 μmol ⋅ min-1 ⋅ 100 g-1; P < 0.05). There was no difference in myocardial lactate release between shunt and control lambs. Oxidation of exogenous glucose, which was approximately zero at rest, increased during exercise in shunt and control lambs. The contribution of glucose and lactate to myocardial oxidative metabolism increased during exercise compared with at rest in both shunt and control lambs. We conclude that myocardial lactate oxidation is higher in shunt than in control lambs, both at rest and during exercise, and that the contribution of carbohydrates in myocardial oxidative metabolism in shunt lambs is higher than in control lambs. Thus it appears that this higher contribution of carbohydrates occurs not only in the case of pressure-overloaded hearts but also in myocardial hypertrophy due to volume overloading.

Determination of organ substrate oxidation in vivo by measurement of 13CO2 concentration in blood

Substrate oxidation by various organs in animals as well as in humans is usually studied by experiments in which radioactively labeled substrates are used and the production of 14CO2 is measured. In vivo, substrate oxidation by an organ has, up to now, not been determined by means of stable isotopes. Problems in the determination of the concentration of 13CO2 in blood may have impeded the use of 13C-labeled substrates. For the determination of 13CO2 concentration in blood a direct method for the determination of total CO2 concentration in blood was combined with the determination of the isotope ratio (13C/12C) of CO2 by isotope ratio mass spectrometry. The intra-assay relative standard deviation of the CO2 concentration (mean: 19.26 mmol l-1; n = 7) was 0.8%. The inter-assay relative standard deviation of the CO2 concentration in solutions of a weighed amount of Na2CO3 determined over a 5 year period was 0.64% (mean: 21.99 mmol l-1; n = 22). The intra-assay relative standard deviation of 13C in CO2 was 0.03% (mean 13C/12C: 0.0111557; n = 5). From the 13CO2 concentration in arterial and venous blood, substrate oxidation by various organs can be calculated. As an illustration, the determination of myocardial glucose oxidation in lambs, both at rest and during exercise, is described.

Oral propafenone as treatment for incessant supraventricular and ventricular tachycardia in children

Abstract Incessant tachycardia, which can result in tachycardiainduced cardiomyopathy, is difficult to treat with conventional drugs. Better results are obtained with class Ic antiarrhythmic agents, but they may elicit proarrhythmias. 1,2 Propafenone appears to be less proarrhythmic. 3 In children with a normal heart, as well as with structural heart disease, oral propafenone has been used in different types of tachyarrhythmias including ventricular ectopy and paroxysmal tachycardia. 4–9 In incessant tachycardia, however, the experience with oral propafenone is limited. Therefore, we studied the efficacy and side effects of oral propafenone in children with incessant supraventricular and ventricular tachycardia.