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 select how you would like to proceed. Keep the current affiliation with [InstitutionA] and continue with the Access profile sign in process Switch affiliation to [InstitutionB] and continue with the Access profile sign in process 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 Error: Incorrect UserName or Password Username Error: Please enter User Name Password Error: Please enter Password Sign in Forgot Password? Forgot Username? Sign in via OpenAthens Sign in via Shibboleth You already have access! Please proceed to your institution's subscription. Create a free profile for additional features.