Presentation and prognosis of complete atrioventricular block in childhood, according to maternal antibody status.

OBJECTIVES: We sought to determine whether the presentation and prognosis of children with complete atrioventricular block (CAVB) were related to maternal antibody status. BACKGROUND: Comparative studies related to the presence or absence of maternal antibodies anti-SSB/La and anti-SSA/Ro are lacking in children with isolated complete CAVB. METHODS: From 1980 to 2004, we screened for maternal antibodies in 111 children <15 years old with CAVB. According to the presence (Ab+) or absence (Ab-) of antibodies, 2 groups of patients were retrospectively compared. RESULTS: The study group included 56 Ab+ and 55 Ab- patients with equal gender distribution. A total of 96% Ab+ patients were diagnosed in utero or within the first month, compared with 24% Ab- patients. Progression from incomplete to complete block was shown in 23 Ab- and 2 Ab+ patients. Echocardiography showed normal heart structures in Ab- patients, but 8 Ab+ patients had ostium secundum or ductus arteriosus. Pacemaker implantation was performed in 105 patients, and age at implantation was younger in the Ab+ group. At follow-up (age 9.7 +/- 6 years), all Ab- patients were alive with normal left ventricular function; dilated cardiomyopathy was diagnosed at diagnosis or during follow-up in 16 Ab+ patients, and 6 of 16 have died. CONCLUSIONS: Patients with antibody-mediated CAVB were diagnosed and underwent pacing earlier in life and had a more severe prognosis than Ab- patients because of a high risk of dilated cardiomyopathy. The absence of antibody suggests a different pathologic mechanism than autoimmunity, and the term congenital may be not appropriate in these cases.     

Congenital heart block: development of late-onset cardiomyopathy, a previously underappreciated sequela

OBJECTIVE: We report 16 infants with complete congenital heart block (CHB) who developed late-onset dilated cardiomyopathy despite early institution of cardiac pacing. BACKGROUND: Isolated CHB has an excellent prognosis following pacemaker implantation. Most early deaths result from delayed initiation of pacing therapy or hemodynamic abnormalities associated with congenital heart defects. METHODS: A multi-institutional study was performed to identify common clinical features and possible risk factors associated with late-onset dilated cardiomyopathy in patients born with congenital CHB. RESULTS: Congenital heart block was diagnosed in utero in 12 patients and at birth in four patients. Ten of 16 patients had serologic findings consistent with neonatal lupus syndrome (NLS). A pericardial effusion was evident on fetal ultrasound in six patients. In utero determination of left ventricular (LV) function was normal in all. Following birth, one infant exhibited a rash consistent with NLS and two had elevated hepatic transaminases and transient thrombocytopenia. In the early postnatal period, LV function was normal in 15 patients (shortening fraction [SF] = 34 +/- 7%) and was decreased in one (SF = 20%). A cardiac pacemaker was implanted during the first two weeks of life in 15 patients and at seven months in one patient. Left ventricular function significantly decreased during follow-up (14 days to 9.3 years, SF = 9% +/- 5%). Twelve of 16 patients developed congestive heart failure before age 24 months. Myocardial biopsy revealed hypertrophy in 11 patients, interstitial fibrosis in 11 patients, and myocyte degeneration in two patients. Clinical status during follow-up was guarded: four patients died from congestive heart failure; seven required cardiac transplantation; one was awaiting cardiac transplantation; and four exhibited recovery of SF (31 +/- 2%). CONCLUSIONS: Despite early institution of cardiac pacing, some infants with CHB develop LV cardiomyopathy. Patients with CHB require close follow-up not only of their cardiac rate and rhythm, but also ventricular function.     

Natural history of dilated cardiomyopathy in children

To assess the natural history and potential risk factors in childhood dilated cardiomyopathy, we investigated 25 patients (ages 9.6 +/- 4.4 years) who presented after they were 2 years old. All patients had symptoms of congestive heart failure and reduced contractility with a dilated left ventricle at presentation. Two factors at presentation were significantly different between patients who died less than 1 year after the presentation (n = 14) and those who survived for more than 1 year (n = 9); cardiothoracic ratio (65.1% +/- 6.8% vs 57.1% +/- 6.1%, p less than 0.01) and left ventricular ejection fraction (31.3% +/- 7.0% vs 40.0% +/- 6.2%, p less than 0.05). Irrespective of intensive medical therapy, dilated cardiomyopathy in children had a poor prognosis; the actuarial survival rate was 41% at 1 year and 20% at 3 years. Other forms of therapy should be considered in the early stages of dilated cardiomyopathy in this high-risk group.     

Prevalence and clinical background of exercise-induced ventricular tachycardia during exercise testing

OBJECTIVES: This study assessed the prevalence and clinical background of exercise-induced ventricular tachycardia during exercise testing. METHODS: Complications during exercise testing were reviewed in 25,075 consecutive patients, 14,037 men and 11,038 women, who underwent a total of 47,656 maximal treadmill or bicycle exercise tests between April 1985 and March 1999. The mean age of the patients was 53.3 +/- 8.8 (mean +/- SD) years. Non-sustained ventricular tachycardia was defined as 8 or more consecutive ventricular ectopic beats at > 100 beats/min. A total of 126 patients undergoing exercise testing to evaluate the efficacy of pharmacotherapy for ventricular tachycardia were excluded. RESULTS: The major reasons for the exercise test were chest pain (27.0%) and screening (20.3%). Twenty patients (0.08%) had exercise-induced ventricular tachycardia. Six patients had ischemic heart disease, two had cardiomyopathy, five had other cardiac diseases, and seven patients showed no clinical evidence of heart disease. The incidence of ventricular tachycardia in patients with cardiomyopathy (2/109) was higher than in other patients, but the number of patients with ventricular tachycardia was small. Ventricular tachycardia was documented at heart rates of more than 80% of predicted maximal heart rate in 12 of the 20 patients. CONCLUSIONS: These results suggest that the exercise testing can be done safely when the end-point criteria are properly applied.     

The interruption of atrioventricular conduction by cardiac fulguration in patients with supraventricular tachycardias. The mid- and long-term results]

Catheter ablation of the atrioventricular node is a therapeutic technique for the treatment of patients with drug-refractory supraventricular tachyarrhythmias. In our Arrhythmia Unit 25 patients (8 women, 17 men) aged (mean +/- DE) 56 +/- 10 years have undergone fulguration of the atrioventricular junction since 1986. The more frequent treated rhythm disturbance was atrial flutter or fibrillation, with uncontrolled rapid ventricular response. Absence of organic heart disease was diagnosed in 9 patients; the remainder had valvular heart disease (2), cor pulmonale (2), cardiomyopathy (7), hypertensive heart disease (2) and Wolff-Parkinson-White syndrome (3). Under general anesthesia 1.8 +/- 0.8 shocks/patients were delivered along 1.2 +/- 0.7 sessions/patient. In 23 of 25 patients (92%) complete atrioventricular block was achieved, and a pacemaker was implanted. There were no complications. The other 2 patients were referred to surgery for cryoablation of the atrioventricular junction. Patients were followed for an average of 21 +/- 12 months. Four patients have died: two due to congestive heart failure, which was present prior to the ablation procedure, the third because of a metastatic carcinoma, and the fourth had a sudden death 14 months after the procedure (he had dilated cardiomyopathy and Wolff-Parkinson-White syndrome). The remainder in chronic stable complete atrioventricular block are asymptomatic for arrhythmias and without antiarrhythmic medication.     

Clinical and immunologic characteristics in peripartum cardiomyopathy

Peripartum cardiomyopathy (PPCM) is a rare disorder of dilated cardiomyopathy and left ventricular dysfunction occurring in the last month of pregnancy or within 5 months postpartum. Outcome of PPCM is highly variable, comprising clinical improvement and rapid deterioration unresponsive to medical treatment requiring heart transplantation or even death. In this study, we report the clinicopathologic findings of 10 patients with PPCM who were retrospectively identified in our cardiomyopathy registry. During a follow-up of 69+/-27 months, no patient died or required orthotopic heart transplantation. Left ventricular ejection fraction was 38+/-7% at the time of diagnosis and 53+/-7% during follow-up. While all patients had sinus rhythm at the time of diagnosis, three patients presented with left bundle branch block. We found no evidence of viral infection in endomyocardial biopsy samples of seven patients by PCR. Histopathologic findings revealed the presence borderline myocarditis in two of seven patients (29%). Circulating autoantibodies to cardiac tissue of any kind were observed in all patients. In conclusion, in our retrospective observational study, no patient diagnosed with PPCM died or received orthotopic heart transplantation. Improvement of left ventricular ejection fraction was present in eight patients (80%), while LV dysfunction persisted in four patients. Our findings support the hypothesis of an underlying autoimmune pathomechanism in this rare disease.     

Dilated cardiomyopathy in childhood: prognostic features and outcome

The natural history of dilated cardiomyopathy in children is difficult to predict due to the heterogeneous character of the disease. The outcome in infants and children is highly variable from complete recovery to death. In this study, 40 children diagnosed with dilated cardiomyopathy between 1995 and 2004 in our paediatric cardiology unit were reviewed with respect to clinical course and outcome, retrospectively. The medical history of these patients with dilated cardiomyopathy was reviewed to determine age, gender, family history, preceding viral illness, duration of symptoms before the diagnosis, symptoms and signs at presentation, treatment and outcome. The diagnosis was made on the basis of cardiomegaly and evidence of poor left ventricular function by echocardiography. Median age at diagnosis was 14 months, ranging from 2 months to 8 years. At presentation, 28 patients (70%) were under and twelve (30%) were above the age of two years. Twenty-eight (70%) patients had signs of congestive heart failure. Mean duration of follow-up was 40 +/- 24 months (ranging from 6 months to 9 years), 21 patients (52.5%) recovered, 17 patients (42.5%) had residual disease and two (5%) died. The cause of death in both patients was progressive cardiac failure. Sixteen of 28 patients (57%) who were below the age of two years and five of 12 patients (42%) who were above the age of two years at presentation recovered. The rate of recovery was significantly different between the two age groups (p < 0.05). Seventeen of 21 (81%) patients with a history of recent viral illness at presentation recovered. The mean duration of the disease among those who recovered was 11 +/- 8.3 months. Five of 19 (26%) patients without recent viral illness recovered. The mean duration of the disease in this group was 22 +/- 12 months. There was a significant difference between the two groups with respect to recovery and recovery time (p < 0.05). During the first 6 months after diagnosis, there was a significant difference between the patients who recovered and the patients who had residual disease with respect to improvement in the left ventricular FS (22 +/- 3.5%, 15.2 +/- 2.8%, respectively) (p < 0.05). In conclusion, in this study, the rate of recovery and survival is higher than in previous studies. A good outcome is related to age at presentation (< or = two years old), a history of viral disease within three months of presentation and improvement in ventricular function during the first 6 months after diagnosis. Intractable heart failure has an adverse effect on the outcome.     

Prognosis of patients with congestive heart failure: its determinants in various heart diseases in Japan.

We investigated the prognosis of patients with congestive heart failure (CHF) and the factors which influence the prognosis of Japanese patients with this condition. From among the patients admitted to our hospital from January 1, 1978 to December 31, 1985, the 298 patients who were diagnosed having CHF were investigated. Patients with CHF had a rather poor prognosis, with the 1-year, 3-year, and 5-year cumulative survival rates being 76%, 60%, and 49%, respectively. The factors influencing the prognosis of patients with CHF were the type of underlying heart disease, the left ventricular ejection fraction, the left ventricular end-diastolic dimension, and the central venous pressure. Survival rates differed significantly depending on the type of underlying heart disease. The cumulative 5-year survival rate was 35% for coronary artery disease, 40% for dilated cardiomyopathy, 53% for rheumatic valvular heart disease, and 80% for hypertensive heart disease.     

Hemodynamics during chronic amiodarone administration in Japanese patients with idiopathic dilated cardiomyopathy and ventricular arrhythmia: a retrospective study

OBJECTIVES: Nonischemic heart disease, especially idiopathic dilated cardiomyopathy, is relatively common among Japanese patients receiving amiodarone for concomitant ventricular arrhythmia, but the hemodynamic effects of amiodarone in these Japanese patients are unclear. The hemodynamic changes during chronic amiodarone administration were retrospectively studied in patients with idiopathic dilated cardiomyopathy and ventricular arrhythmia. METHODS: Fifty-two patients [42 males, 10 females, 53 +/- 2 years (mean age +/- SE)] with ventricular tachyarrhythmia and idiopathic dilated cardiomyopathy with left ventricular ejection fraction of 27 +/- 1% (mean +/- SE) were treated with 200-400 mg daily of oral amiodarone as the loading dose for the initial 14 days and 100-200 mg daily maintenance dose for a further 6 months. No patients were taking beta-blockers or positive inotropic drugs. Echocardiographic examination was performed before (baseline), at week 2 and at month 6 of amiodarone therapy. Twenty four-hour Holter monitoring during the same time period was also performed in 34 patients. Seventeen patients underwent right heart catheterization before and at week 2. RESULTS: Echocardiographic measurements showed no significant change in left ventricular end-diastolic dimension, although there was a slight increase in fractional shortening from 16 +/- 1% to 19 +/- 1% (p < 0.05) and 18 +/- 1% (mean +/- SE) (p < 0.01) at week 2 and month 6 of amiodarone therapy, respectively. Amiodarone markedly reduced the mean heart rate and the frequency of premature ventricular complexes on ambulatory monitoring. The cardiac index did not change and the pulmonary capillary wedge pressure tended to decrease slightly at week 2 in the 17 patients who underwent catheterization. CONCLUSIONS: This retrospective study showed no worsening of the hemodynamic state during chronic amiodarone administration in Japanese patients with idiopathic dilated cardiomyopathy and ventricular arrhythmia.     

Myocardial creatine concentration in various nonischemic heart diseases assessed by 1H magnetic resonance spectroscopy.

BACKGROUND: Previous (31)P magnetic resonance spectroscopy (MRS) studies demonstrated that the myocardial phosphocreatine-to-ATP ratio offered important information concerning the degree of dysfunction and prognosis in patients with cardiomyopathy. In the present study, we investigated total creatine (CR) levels in various diseased hearts using 1H MRS. METHODS AND RESULTS: Fourteen patients with the following conditions were examined: cardiac amyloidosis (n = 2); hypertensive heart disease (4); valvular disease (2); hypertrophic cardiomyopathy (2); dilated cardiomyopathy (2); restrictive cardiomyopathy (1); and post-operative atrial septal defect (1). Myocardial CR was measured using 1H MRS with point-resolved spectroscopy localization. Overall, myocardial CR levels in diseased hearts were significantly lower than those in the control group [16.5+/-6.0 (n = 14) vs 27.1+/-3.2 micromol/g (n = 10), p < 0.001]. There was a positive correlation between myocardial CR and left ventricular ejection fraction (42.9+/-13.8%, range 19.5-69.1%) despite the different mechanisms of cardiac dysfunction (r = 0.60, p < 0.05). Myocardial CR levels in patients who were hospitalized due to heart failure within 1 year were significantly lower than those in other patients [11.3+/-1.0 (n = 4) vs 18.6+/-5.9 micromol/g (n = 10), p < 0.05]. CONCLUSIONS: Noninvasive measurement of myocardial CR using 1H MRS may be valuable in the assessment of disease severity and prediction of clinical course in various forms of heart disease.     

Prognostic implications of complex ventricular ectopy in patients with and without structural heart disease. A study based on programmed electrical stimulation

Fifty-six patients with complex ventricular premature beats (Lown grade IVa, IVb), but no evidence of ventricular tachycardia on 48 hours of continuous monitoring were evaluated by programmed electrical stimulation. Thirty patients had coronary atherosclerotic heart disease, 3 had valvular heart disease, 2 had cardiomyopathy and 21 had no structural heart disease. Programmed stimulation identified two groups of subjects: Group I comprised 11 patients in whom ventricular tachycardia was induced and Group II comprised 45 patients (which included 21 patients without heart disease) in whom no ventricular tachycardia was induced. The incidence of left ventricular dysfunction (ejection fraction less than 40%) was significantly higher in Group I as compared to Group II (P less than 0.001). There was, however, no difference between the grade of ventricular ectopy, HV interval or the incidence of bundle branch block between the 2 groups. Patients with inducible ventricular tachycardia (Group I) were put on laboratory directed anti-arrhythmic drug therapy. Patients without inducible tachycardia (Group II) were not given anti-arrhythmic therapy. The patients were followed up for 34 +/- 10 months. The incidence of sudden death (36.3% vs 6.6%, P less than 0.001) was significantly higher in Group I as compared to Group II. No patients without structural heart disease died during the follow-up. Programmed electrical stimulation fails to induce ventricular tachycardia in patients with complex ventricular ectopy but no structural heart disease. It is, however, possible to define a high risk subset in patients with structural heart disease and complex ectopy. The high risk patients with inducible ventricular tachycardia do not seem to benefit by anti-arrhythmic drugs, which may independently increase the risk of sudden death in treated patients. Patients in whom ventricular tachycardia is not inducible have better left ventricular function, a good long-term prognosis and do not require anti-arrhythmic agents.     

Characteristics of congestive heart failure accompanied by atrial fibrillation with special reference to tachycardia-induced cardiomyopathy.

BACKGROUND: Sustained tachycardia causes left ventricular (LV) systolic dysfunction leading to heart failure (HF), which is widely known as "tachycardia-induced cardiomyopathy (TIC)", but its prevalence and prognosis in Japanese remain unclear. METHODS AND RESULTS: Of 213 consecutive patients with HF associated with atrial fibrillation (AF) requiring hospitalization (n=213) between January 1999 and December 2004, and 104 (83 males, 67+/-12.6 years) were identified as not having any structural heart disease. Of them 41 (39%) had a normal LV ejection fraction (LVEF) at the initial admission, and the remaining patients fell into 2 groups: those with rapid (<6 months) normalization of the LVEF after AF management (presumed TIC, 30 patients, 29%) and those with persistent LV systolic dysfunction (dilated cardiomyopathy (DCM), 33 patients, 32%). Although the B-type natriuretic peptide value and LVEF did not differ between the 2 groups, the LV size on admission was significantly smaller in the TIC group (LV end-diastolic dimension (LVDd) 57.6+/-7.2, LV end-systolic dimension (LVDs) 49.4+/-8.0) than in the DCM group (LVDd 63.4 +/-8.8, LVDs 55.3+/-9.6, p<0.05). During a follow-up period of 42.1+/-21.2 months, cardiac death and recurrent HF hospitalization were significantly less frequent in the TIC group than in the DCM group. CONCLUSIONS: In AF-associated HF requiring hospitalization, TIC is the presumed cause in approximately one-third of patients without any previously known structural heart disease. That particular group is characterized by a relatively smaller LV and better prognosis under medical treatment.     

Severe dilated cardiomyopathy and quadriceps myopathy due to lamin A/C gene mutation: a phenotypic study

This study reports a family affected by a new phenotype associated with dilated cardiomyopathy and quadriceps myopathy. METHODS: 29 family members underwent a physical and neurological examination, including an electromyogram and biopsy of muscle abnormalities. A cardiac examination was performed in all subjects. RESULTS: The family pedigree (n=72) demonstrated that transmission was autosomal dominant. Eleven subjects had cardiac involvement, only four had quadriceps muscle involvement. Cardiac impairment preceded neurological involvement. The mean age for neurological involvement was 44+/-0.8 years (range 43-45) and cardiac involvement was 37+/-7.9 years (range: 24-45). Cardiac involvement consisted of: hypokinetic dilated cardiomyopathy (64%); atrial fibrillation (100%); ventricular arrhythmias (64%); impaired conduction with bundle branch or complete atrio ventricular block (73%). Four patients required pacemakers and anti arrhythmic therapies. Four patients died: two of refractory heart failure and two of sudden death; two patients were resuscitated following cardiac arrest. Three patients required a prophylactic implantable cardiac defibrillator (ICD). Muscle morphological abnormalities were characterized by a variable number of fibers with rimmed vacuoles. The quadriceps deteriorated progressively without impairment of other muscles. Genotypic study showed a lamin A/C gene mutation. CONCLUSIONS: This family was affected by a new phenotype composed of an autosomal dominant severe dilated cardiomyopathy with conduction defects or arrhythmias and quadriceps myopathy. Cardiac abnormalities preceded neuromuscular disorders and defined the prognosis of this disease.     

Clinical course of idiopathic dilated cardiomyopathy in children

Previous studies in adults with dilated cardiomyopathy suggest that the presence of arrhythmia, especially ventricular tachycardia, correlates with increased mortality. We performed a retrospective analysis of 63 children with idiopathic dilated cardiomyopathy to determine the prognostic significance of arrhythmias and other findings with respect to mortality. The mean age at diagnosis of the cardiomyopathy was 4.96 +/- 5.3 years. The overall mortality rate was 16% over a 10 year follow-up period. Persistent congestive heart failure and ST-T wave changes correlated with increased mortality (p less than 0.05). No other variables affected outcome. Arrhythmias were found in 46% of the patients; of the arrhythmias, 48% were atrial arrhythmias. Ventricular tachycardia was present in six patients. Death occurred in 4 (14%) of 29 patients with known arrhythmia; 1 of the 5 died suddenly. The remaining 6 deaths in the series occurred in the 34 patients without a documented arrhythmia. It is concluded that 1) arrhythmias are frequently seen in children with dilated cardiomyopathy but are not predictive of outcome; 2) sudden death in children with this disease is rare; and 3) persistent congestive heart failure portends a poor prognosis.     

Mitochondrial respiratory chain activity in idiopathic dilated cardiomyopathy

BACKGROUND: Cardiomyopathy is well recognized in mitochondrial diseases in which it has been associated with defects of mitochondrial function, including cytochrome-c oxidase (COX) deficiencies. This study explores the respiratory chain activity, particularly of COX, in patients with cardiomyopathy to determine whether a relationship exists between respiratory enzyme activity and cardiac function. METHODS AND RESULTS: Myocardial specimens from the left ventricular wall of explanted hearts were obtained from subjects with ischemic (n = 6) or nonischemic dilated (n = 8) cardiomyopathy. Assays for citrate synthase (CS) and complexes II/III and IV activity were performed on cardiac mitochondria and homogenate. Enzyme activities were normalized to CS activity and compared with control activities (n = 10). A significant reduction in COX and/or CS activity was identified in mitochondrial preparations from the transplant group and correlated significantly with ejection fraction (P < .05), although this does not prove a causal relationship. Significantly reduced CS activity in homogenate was identified, suggesting decreased mitochondrial volume in addition to decreased COX activity. Measurements in cardiac homogenates failed to show a significant reduction in COX activity (P > .05) in the transplant group, suggesting that the use of prefrozen tissue homogenates may underestimate existing mitochondrial respiratory defects in cardiac tissue. CONCLUSIONS: Mitochondrial function is altered at a number of levels in end-stage cardiomyopathy. Defective COX activity resulting in deficient adenosine triphosphate generation may contribute to impaired ventricular function in heart failure. Agents capable of improving mitochondrial function may find an adjuvant role in the treatment of cardiac failure.     

Prognostic value of cardiopulmonary exercise testing in children with heart failure secondary to idiopathic dilated cardiomyopathy in a non-beta-blocker therapy setting

BACKGROUND: Peak oxygen consumption and resting left ventricular ejection fraction (LVEF) are independent predictors of survival in adult heart failure (HF) patients. Aim: To evaluate these factors in children. METHODS: We prospectively studied 31 children with NYHA class I to III HF (mean LVEF 26+/-10%; mean age 8.6+/-1.9 years). All had dilated cardiomyopathy and were awaiting heart transplantation. A cardiopulmonary treadmill exercise test was performed and LVEF determined by radionuclide ventriculography. RESULTS: During a median follow-up of 1282 days, 20 children reached at least one end-point (death or heart transplantation). Clinical data from the 11 children without events and the 20 children with events are as follows: NYHA class 1+/-0 vs. 2+/-0.9 (p<0.01); SBP 118+/-17 vs. 102+/-16 (p=0.01); DBP 70+/-10 vs. 61+/-10 (p=0.02); heart rate 165+/-22 vs. 148+/-22 (NS); double-product 19+/-4 vs. 15+/-4 (p=0.01); end-tidal carbon dioxide tension (PetCO2) 35+/-5 vs. 30+/-6 (NS); oxygen consumption (VO2) 22+/-5.4 vs. 18.3+/-5.7 (NS); exercise time 19+/-4 vs. 13+/-6 (p<0.003), and LVEF 31+/-8 vs. 22+/-10 (p=0.02). These variables all correlated with prognosis on univariate analysis. In multivariate analysis, only decreasing exercise time and LVEF were predictive of events during follow-up (p<0.001 and 0.04). CONCLUSION: These findings suggest that reduction in LVEF and exercise tolerance in children with heart failure is predictive of functional status.     

Timing and magnitude of serum creatine kinase-MB after transcatheter cardiac tissue fulguration in man

This study examined the impact of transcatheter fulguration on creatine kinase-MB release in 21 patients (age range 17-71 years). Arrhythmia diagnoses were ventricular tachycardia 9, atrial fibrillation with a rapid ventricular response 7, atrioventricular nodal reentry 2, and reciprocating tachycardia utilizing a posteroseptal accessory pathway 3. Seven patients had apparently normal hearts while 8 had ischemic heart disease and 6 cardiomyopathy. Timing of initial elevated creatine kinase-MB activity (mean 1.34 +/- 0.69 SD hours) and peak creatine kinase-MB activity (mean 3.73 +/- 0.89 SD hours) was relatively uniform in all patients. Time to peak creatine kinase-MB activity was unrelated to either underlying cardiac disease (normal: 3.9 +/- 1.0 hours; ischemic heart disease: 3.5 +/- 0.9 hours; cardiomyopathy: 3.8 +/- 0.9 hours), or fulguration site (His bundle (n = 9): 4.2 +/- 0.9 hours, proximal coronary sinus (n = 3): 3.3 +/- 0.3 hours, ventricle (n = 9): 3.4 +/- 0.8 hours). The magnitude of peak serum creatine kinase-MB activity was independent of myocardial diagnosis or fulguration site, but was linearly related to total energy delivered (r = 0.5, P less than 0.022). The latter correlation was particularly strong within cardiac diagnosis subgroups (normal: r = 0.92, P less than 0.002; ischemic heart disease: 0.73, P less than 0.04; non-ischemic cardiomyopathy: r = 0.57, P = NS). Thus, serum creatine kinase-MB activity following transcatheter fulguration is linearly related to the magnitude of delivered energy, and is similar to that observed after transient coronary artery occlusion and reperfusion.     

Clinical profile and outcome of restrictive cardiomyopathy in children.

The clinical profile and outcome of idiopathic restrictive cardiomyopathy in a group of eight children are reviewed. There were six girls and two boys. Age at presentation was 4.0 +/- 2.6 years (range 1.3 to 9.5 years). All patients had evidence of congestive heart failure with systemic venous congestion. Right or left atrial enlargement was the most consistent ECG finding and was present in all patients. Left ventricular shortening fraction was normal in five patients, increased in two, and mildly reduced in one. The most striking echocardiographic feature was severe biatrial dilatation in the presence of normal or near-normal ventricular cavity dimensions. Marked elevation of left ventricular end-diastolic pressure was noted in all seven patients undergoing cardiac catheterization (34 +/- 7 torr; range 24 to 40 torr). Right ventricular end-diastolic pressure was elevated but significantly different from left ventricular pressure (18 +/- 7 torr; p less than 0.01). A characteristic early diastolic dip with a rapid rise to an elevated plateau (square root sign) was present in five of seven patients. Median survival was 1.4 years. Six patients died 0.2 to 7.0 years after they were initially seen. The actuarial survival rate 1.5 years after presentation was 44%, decreasing to 29% at 4 years. Restrictive cardiomyopathy has a worse prognosis in children than in adults. In part this may reflect the more advanced symptoms of congestive failure at initial presentation. Pediatric patients should be considered for early cardiac transplantation.     

Value of the isoprenaline test in arrhythmogenic heart diseases

The sympathetic nervous system seems to play a major role in the genesis of ventricular arrhythmias. The authors studied this adrenergic factor prospectively by exercise stress testing and intravenous isoprenaline in 107 patients referred for evaluation of arrhythmias or symptoms thought to be due to arrhythmias: 30 patients had morphologically normal hearts (15 ventricular extrasystoles, 15 bursts of ventricular tachycardia); 55 patients had dilated cardiomyopathy and 22 had probable or proven arrhythmogenic right ventricular dysplasia. Exercise testing was carried out with 30 watt increments every 3 minutes. Ventricular tachycardia was induced in 6 patients with apparently normal hearts (17%), 13 patients with dilated cardiomyopathy (31%) and 7 patients with arrhythmogenic right ventricular dysplasia (40%). Isoprenaline was infused for 3 minutes at a dose of 8-12 g/min: ventricular tachycardia was induced in 7 patients with apparently normal hearts (24%) and 23 patients with dilated cardiomyopathy. In some patients presenting with syncope, an arrhythmogenic response to isoprenaline was the only abnormality detected by the study protocol. An arrhythmia was induced by isoprenaline in 17 of the 18 patients with confirmed right ventricular dysplasia (94%), 12 of whom had sustained mono or polymorphic ventricular tachycardia. Two of these patients did not have significant right ventricular wall motion abnormalities. Four asymptomatic subjects related to patients with right ventricular dysplasia underwent the isoprenaline test; bursts of ventricular tachycardia were recorded in 3 of them. Polymorphic ventricular tachycardia was specifically associated with cardiac disease. The maximum heart rate attained by exercise testing (148 +/- 19/min) was higher than that attained with isoprenaline (148 +/- 22/min).(ABSTRACT TRUNCATED AT 250 WORDS)     

Efficacy of a dual chamber defibrillator with atrial antitachycardia functions in treating spontaneous atrial tachyarrhythmias in patients with life-threatening ventricular tachyarrhythmias.

BACKGROUND: Atrial fibrillation has a high incidence in patients wearing an implantable cardioverter defibrillator for ventricular tachyarrhythmias and may lead to palpitations, heart failure, angina, stroke and inappropriate defibrillator discharge. The aim of the study was to evaluate the efficacy of a dual chamber defibrillator with atrial antitachycardia functions in treating spontaneous atrial tachyarrhythmias. METHODS: One hundred and twelve patients, 88 male, mean age 64+/-11 years, were enrolled. Seventy-six had ischaemic heart disease, 21 idiopathic dilated cardiomyopathy, nine other heart diseases, six no structural heart disease. The mean left ventricular ejection fraction was 40+/-11%. Sixty-two had prior atrial tachyarrhythmias. RESULTS: Follow-up lasted 11+/-9 months (range 1-42). Among 933 ventricular tachyarrhythmia episodes, 100% of ventricular fibrillation and 92% of ventricular tachycardia were successfully cardioverted. Among 414 detected sustained atrial tachyarrhythmias, 195 were classified as atrial tachycardia (47.1%), 192 as atrial fibrillation (46.4%) and 27 (6.5%) as sinus rhythm. The detection-positive predictive value was 93.5%. Therapy success rates: antitachy pacing on atrial tachycardia = 71.3% (crude estimate); 66.1% (adjusted estimate); 50 Hertz on atrial fibrillation=36.2% (crude estimate); 13.5% (adjusted estimate); atrial shock on atrial fibrillation = 62.5% (mean energy 7.8+/-14.1J). Shock efficacy was 32% when delivered energy was < or = 2 atrial defibrillation threshold at implant and 92% when >2. Duration of successfully treated atrial episodes was significantly lower than that of unsuccessfully treated (6+/-26 min vs 42+/-60). CONCLUSIONS: Atrial antitachy pacing and shock therapies demonstrated very high efficacy in treating atrial tachyarrhythmias in defibrillator patients.