Mitral valve prolapse in myotonic dystrophy

Neuromuscular Disease: Cardiac Manifestations and Sudden Death Risk

Cardiovascular complications of neuromuscular diseases disproportionately affect the cardiac conduction system. Cardiomyopathy and cardiac arrhythmias produce significant morbidity and mortality. Patients with neuromuscular diseases should be carefully and frequently evaluated for the presence of bradycardia, heart block, and tachyarrhythmias. Preemptive treatment with permanent pacemakers or implanted defibrillators is appropriate in patients with conduction system disease or who are at risk for ventricular arrhythmias.

Myotonic dystrophy type I in childhood Long-term evolution in patients surviving the neonatal period

In a retrospective study, 32 patients with myotonic dystrophy, including congenital (n=17) and infantile/juvenile forms (n=15) were studied during a long follow-up lasting 7-28 years (median: 17 years). The clinical presentation was extremely variable; however, a continuum did exist between severe and less severe congenital forms, and later-onset forms, without genotype-phenotype correlation. We observed some unusual presentations, such as 3 cases of isolated club-feet during the neonatal period, and 7 patients (23%) with a completely isolated mental deficiency, language delay and school failure, who only completed the clinical picture several years later. Wechsler scale testing was performed in all cases, and repeated with 8 patients. It demonstrated a decrease in intellectual abilities in 5 patients, suggesting the possibility of a degenerative cerebral process occurring in these children. This decrease has also been reported in some adult cases. This study illustrates the extremely heterogeneous clinical presentation of myotonic dystrophy in childhood.

Natural history of cardiac involvement in myotonic dystrophy (Steinert's disease): a 13-year follow-up study

Myotonic dystrophy (MD) is associated with a wide spectrum of cardiac abnormalities, but only a few longitudinal studies have investigated the natural course of heart disease in MD. To assess whether neuromuscular involvement significantly predicts cardiac disorders in MD, 83 patients with various grades of disease severity were enrolled in a 13-year follow-up study (mean, 60.6 +/- 37.8 months) that included periodic physical and instrumental cardiac examinations (standard and Holter electrocardiography, echocardiography). During follow-up, muscular disease worsened clinically in 9 patients (11%) whose baseline severity grade changed accordingly; only 3 of them demonstrated parallel worsening of cardiac disturbance, however, compared with a large number of patients who showed additional cardiac abnormalities. These included further worsening of pre-existing pathologic features (19/83) and the appearance de novo of serious arrhythmias and/or conduction defects (23/83). Pacemaker implantation was necessary in 11 of 83 patients (13.2%) who had symptomatic bradyarrhythmias, bifascicular block, and P-R prolongation with a His-to-ventricle interval exceeding 55 ms, as documented by electrophysiologic study. Eight (9.6%) patients died: 2 from noncardiac and 1 from unknown causes, 1 from heart failure, and 4 from sudden death closely related to documented ventricular tachycardia. The incidence and seriousness of arrhythmic and conduction disturbances correlated with the severity of the muscular involvement. Nevertheless, cardiac and muscular disease did not show a linear progression. Cardiac involvement generally worsened more rapidly than did skeletal muscle disease.

Left ventricular diastolic function in congenital myotonic dystrophy

OBJECTIVE

Examination of left ventricular function and conduction abnormalities in myotonic dystrophy.

DESIGN

Twelve patients (median age, 13.7 years) with myotonic dystrophy had detailed electrocardiography and echocardiography performed. Echocardiographic parameters were compared with body surface area (BSA) matched median normal values.

RESULTS

Fractional shortening was slightly reduced (by 28-29%) in three patients and three patients had mild mitral valve prolapse. Diastolic function was abnormal; isovolumic relaxation time (IVRT) and duration of early filling were prolonged compared with control values (median IVRT, 74 v 61 ms). Peak E velocity was increased (median, 0.82 v 0.78 m/s) but atrial phase filling was normal. Heart rate was reduced (median, 68 v 81 beats/min). Conduction abnormalities were common but showed no clear relations with diastolic abnormalities.

CONCLUSIONS

Young patients with myotonic dystrophy have myocardial diastolic dysfunction as well as abnormal electrophysiology. The prognostic implications of such abnormalities require further study.

Intestinal pseudo-obstruction in myotonic dystrophy

We describe four myotonic dystrophy (DM) patients who developed recurrent intestinal pseudo-obstruction. Some episodes were associated with gastroenteritis, while abdominal crowding may have occurred in one case during the third trimester of pregnancy. In most instances, however, no apparent cause could be identified. Intestinal pseudo-obstruction may occur at any stage of DM. In one of our cases intestinal pseudo-obstruction preceded significant muscle weakness by 15 years. Intestinal pseudo-obstruction is usually treated effectively with conservative measures. These include restriction of oral intake, intravenous fluids, and multiple enemas or colonoscopy. Improved intestinal function was noted in one case treated with the prokinetic agent cisapride. A partial sigmoid resection was performed in three cases with dolichomegacolon. No abnormalities were reported on histological examination. Since intestinal pseudo-obstruction is a rare complication of DM, it is of interest that two of our cases are sibs. Review of published reports showed several reports of familial occurrence of specific complications. These include cardiac conduction disturbances, focal myocarditis, mitral valve prolapse, pilomatrixomas, polyneuropathy, normal pressure hydrocephalus, and dilatation of the urinary tract. Myotonic dystrophy may show a tendency to familial clustering of organ specific involvement.

Cardiac involvement in congenital myotonic dystrophy

Seven young patients (mean age 19 years 8 months) with congenital myotonic dystrophy and with defined symptoms at birth were investigated by electrocardiography and echocardiography. None had cardiovascular symptoms. Electrocardiograms or echocardiograms or both were abnormal in all patients. Atrioventricular and intraventricular conduction defects were the most common electrocardiographic abnormalities and were seen in five patients. The echocardiographic examinations showed impaired left ventricular systolic function in one patient. Other echocardiographic findings were a small left ventricle and atrium, minor valve defects, and mitral valve prolapse. This study shows that the heart is often affected in young patients with congenital myotonic dystrophy. The specialised conduction system is often affected and so too is the myocardium, causing impaired systolic function.

Electrocardiographic findings in myotonic dystrophy

Sixty five patients with myotonic dystrophy, from a defined population in northern Sweden with an extremely high prevalence of this disease, were examined by electrocardiography. The patients were subdivided into three groups according to the severity of the disease. Abnormal electrocardiograms were found in 6 (35%) patients with mild disease, 12 (50%) patients with moderate disease, and 23 (96%) patients with severe disease. First degree atrioventricular block and left anterior hemiblock were the most commonly encountered abnormalities in patients with mild and moderate disease, whereas atrial fibrillation and flutter, abnormal Q waves, and repolarisation abnormalities were more common in patients with severe disease. This study shows that the heart is often affected by myotonic dystrophy. These effects can be detected by electrocardiography in early and mild forms of the disease. The effect on the heart is progressive and clinically important atrial arrhythmias and electrocardiographic abnormalities which are useful in differential diagnosis are common in severe forms of the disease.

Cardiac abnormalities in myotonic dystrophy. Electrocardiographic and echocardiographic findings in 65 patients and 34 of their unaffected relatives. Relation with age and sex and relevance for gene detection

Sixty-five patients with a definite diagnosis of myotonic dystrophy (MD) and 34 of their presumably unaffected relatives were examined cardiologically, including ECG in all and echocardiography in 61 and 32 persons respectively, in order to investigate the frequency of cardiac abnormalities, their clinical importance and their potential value as a preclinical marker in the diagnosis of MD. Atrioventricular conduction (AVC) abnormalities were found in 18/33 (54%) of affected males and in only 5/32 (16%) of affected females (P = 0.0025). Intraventricular (IVC) conduction abnormalities were encountered with similar frequency in both sexes: in 12/33 (36%) of affected males and 10/32 (31%) of affected females. Mitral valve prolapses (MVP) were seen more often in affected females: 9/31 (29%) of affected males vs 15/30 (50%) of affected females have MVP (P = 0.16). A previously undescribed finding was that of pericardial effusions in 5 affected and in 1 unaffected person. All affected males with MVP also had conduction abnormalities, but cardiac findings were not interrelated otherwise. None of the cardiac abnormalities mentioned were age-related. Only 8/65 (12%) of patients had cardiac symptoms, all of which were the result of conduction defects. As far as can be judged from a transversal study, the value of cardiac examination of this kind as a preclinical test for the diagnosis of MD is modest. It is argued that IVC-abnormalities, but not AVC-disturbances or MVP, in clinically unaffected relatives may indicate that they are preclinical heterozygotes. The significance of pericardial effusion for the diagnosis of MD awaits further evaluation.