Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content +++ KEY FEATURES +++ ESSENTIALS OF DIAGNOSIS ++ Evidence of progressive muscle wasting and weakness Dilated cardiomyopathy Arrhythmias Hypertrophic cardiomyopathy Conduction abnormalities Arrhythmias Specific genetic diagnosis of a muscular dystrophy +++ GENERAL CONSIDERATIONS ++ Cardiac manifestations of inherited neuromuscular diseases can range from incidental findings on ECG to severe cardiomyopathy Duchenne’s muscular dystrophy: – The most common type (3/100,000 population) of inherited neuromuscular disease – Mainly seen in males (X-linked recessive) – Causes cardiomyopathy – Usually diagnosed in childhood Becker’s muscular dystrophy: – Also sex linked, but with a delayed onset and slower progression than Duchenne’s – The cardiomyopathy is often more severe – Usually diagnosed in childhood Myotonic dystrophy – Autosomal dominant, trinucleotide expansion in the DMPK gene – Associated with myotonia, cataracts, and diabetes – Seen in 1:9000 population – Usually manifests as conduction disturbances and atrial tachyarrhythmias Emery-Dreifuss muscular dystrophy: – An autosomal dominant, recessive, or X-linked disease due to mutations in 6 genes – Usually causes conduction system disease, atrial standstill, and tachyarrhythmias, but can cause hypertrophic or dilated cardiomyopathy Peroneal muscular atrophy (Charcot-Marie-Tooth syndrome): – An autosomal dominant disease – Can cause conduction abnormalities and cardiomyopathy – Often causes atrial standstill – Can cause brady-tachycardia syndromes – Causes heart block in about 50% of cases +++ CLINICAL PRESENTATION +++ SYMPTOMS AND SIGNS ++ Weakness of the affected skeletal muscles or dystonia Dyspnea Syncope Palpitation +++ PHYSICAL EXAM FINDINGS ++ Muscle atrophy Joint contractures Signs of congestive heart failure Murmur of mitral regurgitation +++ DIFFERENTIAL DIAGNOSIS ++ Cardiomyopathy from other causes with muscle atrophy and weakness from inactivity (cardiac cachexia) Conduction, rhythm, and ECG abnormalities from other causes +++ DIAGNOSTIC EVALUATION +++ LABORATORY TESTS ++ Brain natriuretic peptides: elevated Specific genetic analyses Elevated creatine kinase and troponins +++ ELECTROCARDIOGRAPHY ++ Conduction abnormalities, especially atrioventricular block, distal block Ventricular hypertrophy signs Repolarization abnormalities Arrhythmias +++ IMAGING STUDIES ++ Echocardiography may show dilated or hypertrophic cardiomyopathy, diastolic dysfunction, and mitral regurgitation by Doppler MRI may show fatty deposits in the right ventricle of myotonic dystrophy patients +++ TREATMENT +++ CARDIOLOGY REFERRAL ++ Suspected cardiac disease Syncope +++ HOSPITALIZATION CRITERIA ++ Syncope Heart failure +++ MEDICATIONS ++ Therapy as indicated for heart failure Antiarrhythmic drug therapy as appropriate +++ THERAPEUTIC PROCEDURES ++ Pacemaker or implantable cardioverter-defibrillator as indicated +++ SURGERY ++ Cardiac transplantation in selected cases +++ MONITORING ++ ECG monitoring in hospital as appropriate +++... Your Access profile is currently affiliated with '[InstitutionA]' and is in the process of switching affiliations to '[InstitutionB]'. Please click ‘Continue’ to continue the affiliation switch, otherwise click ‘Cancel’ to cancel signing in. Get Free Access Through Your Institution Learn how to see if your library subscribes to McGraw Hill Medical products. Subscribe: Institutional or Individual Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Username? Forgot Password? Sign in via OpenAthens Sign in via Shibboleth