Catecholaminergic polymorphic ventricular tachycardia: electrocardiographic characteristics and optimal therapeutic strategies to prevent sudden death.

OBJECTIVE: To investigate the clinical outcome, ECG characteristics, and optimal treatment of catecholaminergic polymorphic ventricular tachycardia (CPVT), a malignant and rare ventricular tachycardia. PATIENTS AND METHODS: Questionnaire responses and ECGs of 29 patients with CPVT were evaluated. Mean (SD) age of onset was 10.3 (6.1) years. RESULTS: The initial CPVT manifestations were syncope (79%), cardiac arrest (7%), and a family history (14%). ECGs showed sinus bradycardia and a normal QTc. Mean heart rate during CPVT was 192 (30) beats/min. Most cases were non-sustained (72%), but 21% were sustained and 7% were associated with ventricular fibrillation. The morphology of CPVT was polymorphic (62%), polymorphic and bidirectional (21%), bidirectional (10%), or polymorphic with ventricular fibrillation (7%). There was 100% inducement of CPVT by exercise, 75% by catecholamine infusion, and none by programmed stimulation. No late potential was recorded. Onset was in the right ventricular outflow tract in more than half the cases. During a follow up of 6.8 (4.9) years, sudden death occurred in 24% of the patients, 7% of whom had anoxic brain damage. Autosomal dominant inheritance was seen in 8% of the patients' families. beta Blockers completely controlled CPVT in only 31% of cases. Calcium antagonists partially suppressed CPVT in autosomal dominant cases. CONCLUSIONS: CPVT may arise in certain distinct areas but the prognosis is poor. The onset of CPVT may be an indication for an implanted cardioverter-defibrillator.

Response of the stroke volume and blood pressure of young patients with nonobstructive hypertrophic cardiomyopathy to exercise.

Stroke volume (SV), cardiac output (CO) and systolic blood pressure (SBP) were measured during maximal symptom-limited bicycle exercise testing in 13 young patients (age, 11-26 years) with nonobstructive hypertrophic cardiomyopathy (HCM). SV was measured by impedance plethysmocardiography; %SVend, %COend, and %SBPend represent the ratio of the value at termination of the exercise to the respective value at rest. In all patients of HCM-I (the Cardiac Event Group, 3 patients) and 3 of HCM-II (the Non-Cardiac Event Group, 10 patients), the %SVend was less than 100%. The %SVend of HCM-I was significantly lower than the respective values of the HCM-II and Control groups. The %COend values of the HCM-I and HCM-II groups were each significantly lower than that of the Control. The %SBPend values of the HCM-I and HCM-II groups were each significantly lower than that of the Control. Among the HCM patients, the %SVend value was positively correlated with the %SBPend value. The patients who had more severe HCM had poorer exercise-induced increases in SV and SBP. These results suggest that sudden cardiac death in young HCM patients is associated with inhibition of the increase in SV upon exercise.

Idiopathic sustained left ventricular tachycardia in pediatric patients.

BACKGROUND: Idiopathic sustained ventricular tachycardia originating from the left ventricle (ILVT) has been an indication for catheter ablation. The present study evaluated the clinical features, long-term prognosis and indications for treatment in pediatric patients with ILVT. METHODS: The subjects of the present study were eight patients (four males and four females) with a mean age at onset of 11.0 years (range 3-15 years). The mean follow-up period was 7.7 years (range 2.1-11.3 years). RESULTS: In electrophysiologic studies, intravenously administered verapamil was effective for the termination of tachycardia in all six patients who received this treatment and for the prevention of tachycardia in four of five patients. Oral administration of verapamil was effective in five of seven patients. Propranolol or flecainide was added to the treatment protocol for two patients who did not respond to verapamil alone. Tachycardia disappeared without drugs in four patients during the follow-up period and became non-sustained in another patient. Two of three patients with persistent tachycardia underwent catheter ablation. Pharmacologic treatment was very effective for ILVT among these patients. CONCLUSIONS: Pharmacologic therapy, such as with verapamil, is still the treatment of choice for ILVT because of a good long-term prognosis and potential risks and complications by manipulation of catheter ablation.

[A comparison of sudden near maximal exercise test (dash method) and Bruce protocol for pediatric patients].

We examined 24 pediatric patients to evaluate the usefulness of sudden near maximal exercise test (dash method), where the subjects began to run at Bruce protocol of the last stage. 1) No considerable differences between two protocols were found in maximal oxygen consumption (V O2max), maximal heart rate (HRmax), maximal systolic blood pressure, and findings of electrocardiography. 2) The sudden maximal exercise test could be completed during a shorter period compared to Bruce protocol. 3) The sudden maximal exercise protocol reached 84% of HRmax and 47% of V O2max at one minute after the onset of the protocol, and produced 96% of HRmax and 89% of V O2max at two minutes after the onset. We considered that sudden maximal exercise protocol was useful to obtain a response similar to Bruce protocol at maximal exercise within a short period. We have to pay attention to the safety of the patients because their cardiopulmonary response to sudden maximal exercise protocol is dramatic.

An atypical case of cardiomyopathy in a child: hypertrophic or restrictive cardiomyopathy?

A case of an atypical form of cardiomyopathy, in which biopsy showed bizarre myocardial hypertrophy with disorganization, and in which there was no obvious hypertrophy of the interventricular septum and left ventricular free wall, is presented. Ventricular filling was critically impaired, and consequently pulmonary and systemic venous congestion predominated in the clinical presentation which was similar to that of restrictive cardiomyopathy.

Sudden cardiac death in childhood.

To evaluate the mechanism of sudden death in childhood and the physical activity levels at the onset of sudden death, we studied the following items: (1) the incidence and the circumstances surrounding sudden death at school in Kanagawa Prefecture, (2) high risk heart diseases detected among healthy school children by heart disease screening, (3) sudden cardiac death or near miss seen in outpatients with heart disease except congenital heart disease. Among total 15,156,346 school children, sudden death was observed in 97 subjects (M:77, F:20). Annual incidence of sudden death was 6.4 per 10(6). Of the 97 subjects, acute heart failure of unknown etiology was found in 60 (62%), cardiovascular disease in 18 (19%), cerebral vascular accidents in 14 (14%) and heat stroke in 5 (5%). Of the 78 subjects (M:64, F:14) considered as sudden cardiac death, 62 (79%) died during sports activities, and 16 (21%) died at rest. Of the 62 subjects, 29 died during track and field activities and 7 while swimming, both in physical education classes. Eighteen died during athletic club activities and 8 during extracurricular activities. Consequently, 54 subjects (87%) died in the presence of a school teacher. Of the 18 subjects with cardiovascular disease, 9 (hypertrophic cardiomyopathy in 3, myocarditis in 3, Kawasaki disease in 2 and long QT in one) were diagnosed initially by the autopsy study. Latent high risk heart diseases, detected among presumably healthy school children by the heart disease screening program, were the following: hypertrophic cardiomyopathy, long QT syndrome, Kawasaki disease and some arrhythmias (ventricular tachycardia, sick sinus syndrome, A-V block and atrial fibrillation). Follow-up observations of outpatients with heart disease revealed the same results as the heart disease screening program. In order to prevent sudden death at school, the following recommendations should be observed: 1) sports directors should learn "sports medicine in childhood", including primary cardiovascular resuscitation, 2) an accurate heart disease screening program should be operated to detect latent high risk heart diseases, advise on adequate medical treatment, and help ensure an appropriate selection of sports activities, 3) comprehensive autopsy studies should be performed.

[A case of rapidly progressive pulmonary pulmonary hypertension in a 14-year-old girl].

A 14-year-old girl was admitted with chief complaints of edema and chest pain. She had hepatomegaly, but did not have heart murmur and accentuation of the pulmonary component of the second heart sound. The electrocardiogram showed right axis deviation, negative T wave in V3,4 and ST depression in III, aVF. But right ventricular hypertrophy was not dominant. Chest radiography showed a cardiothoracic ratio of 54% and a slight prominence of proximal pulmonary arteries. The edema was soon diminished only by the diuretics, but it appeared again without the diuretics. At the cardiac catheterization 3 months after the onset of symptoms, the pulmonary arterial pressure was 150/85 mmHg and the pulmonary resistance was 3,232 dyn/sec/cm5. The right atrial pressure was 9.5 mmHg and oxygen saturation at the pulmonary artery was 31.0%. Prostaglandin E1 reduced the pulmonary artery pressure only a little, but raised the systemic pressure. The patient was treated with several vasodilators, but her condition deteriorated rapidly and she developed severe right ventricular failure. She died only 8 months after the onset of symptoms and 5 months after the catheterization. At autopsy, histological examination demonstrated intimal fibrotic thickening of the small-sized pulmonary arteries and organizing thrombus. But there was not plexiform lesion. Heart failure was easily improved when she was first admitted. But after 3 months the cardiac catheterization revealed that her condition was already severe. Several vasodilators was not effective to such a rapidly progressive primary pulmonary hypertension.

Idiopathic right ventricular dilation. Special reference to "arrhythmogenic right ventricular dysplasia" and analogous lesions.

Two autopsy cases which showed marked depletion of the right ventricular musculature of the heart accompanied with marked infiltration of the adipose tissue were reported. The first cases was an 18-year-old female who died of right sided congestive heart failure after about 4-years clinical course. The autopsy disclosed marked dilation of the right atrium and ventricle. The entire free wall of the right ventricle was markedly thin. Microscopically, most of the myocardial fibers of the right ventricle were replaced by fat and fibrous tissue. The second case, a 15-year-old boy, whose identical twin was previously diagnosed as arrhythmogenic right ventricular dysplasia designated by Fontaine et al., died suddenly during exercise. He showed no cardiac symptoms but electrocardiogram was abnormal. Autopsy revealed majority of the myocardial fibers of the right ventricular free wall were replaced by fatty tissue. In both cases, fatty infiltration was mainly noticed at the epicardial side and some myocardial fibers remained in the fatty tissue showed hypertrophic and/or degenerative changes. Review of the literature on similar cases showing depletion of the right ventricular musculature including so-called adult's Uhl anomaly, ARVD and dilated right ventricular myocardiopathy was conducted and the relationship of the present cases with these lesions was discussed.

Length-dependent changes of pacemaker frequency in the isolated rabbit sinoatrial node.

To correlate changes in pacemaker frequency with those of length and tension in mammalian atrial tissues, a strip of the sinoatrial (SA) nodal tissue (about 10 mm in length and 4 mm in width) isolated from the rabbit heart was subjected to constant-length and constant-load stretches, and the relation between the resulting pacemaker frequency changes and the segmental length changes of the preparation was examined by means of cinematographic recording of the preparation with carbon markers on its surface. The amount of stretch-induced length changes was larger in the perinodal tissue segments than in the SA nodal segments, indicating that the nodal area is less extensible than the perinodal area. The time course of stretch-induced length changes of one nodal segment (closer to the inferior vena cava) was found to roughly parallel that of pacemaker frequency changes, suggesting that the pacemaker frequency is primarily dependent on the length but not on the tension of the SA nodal area.

Pre- and postoperative arrhythmias in congenital heart disease: from the results of surgery using surface-induced deep hypothermia.

The incidence of arrhythmias in 3614 preoperative patients with congenital heart disease was 1.6 per cent. Pre- and postoperative serial ECGs in 186 patients with an isolated VSD and in 58 patients with TOF were reviewed. The incidence of CRBBB and CRBBB-LAH following VSD repair was 33% and 6.6%, respectively, and for TOF was 55% and 5.2%, respectively. Complete A-V block (CAVB) was seen in 2 patients following VSD repair, and none of TOF patients developed CAVB. Late cardiac or dysrrhythmic death was not recognized in our limited follow up period. The indications for surgery in membranous VSD should be determined more carefully, because the risk of the surgical damage to the conduction system is still higher. Moreover, we must keep in mind that damage to the A-V conduction system may occur naturally even in a patient with small VSD. Finally, it can never be overemphasized that physicians must pay attention to the occurrence and course of postoperative arrhythmias.