Review articleCardiac function tests in neuromuscular diseases
Section snippets
Neuromuscular diseases with cardiac involvement
The symptoms caused by cardiac disease in neuromuscular disorders depend on the type and severity of involvement and the degree of skeletal muscle disability. In Duchenne and Becker muscular dystrophies, abnormal amounts of dystrophin in cardiac myocytes lead to their necrosis and fibrosis with resultant cardiomyopathy [1], [2], [3], [4]. Symptoms of congestive heart failure, such as dyspnea, fatigue, orthopnea, and edema, are seen with varying frequency. The development of symptoms is
The cardiac physical examination
Cardiac physical examination findings in neuromuscular diseases are not specific to any one disorder. The presence of abnormal examination findings can be the first indication of underlying cardiac involvement and can serve as a clue to the type of involvement. Cannon (amplified) a-waves in the jugular venous pulse suggest dissociation of atrial and ventricular contraction and can be seen with complete heart block, whereas loss of a-waves is seen with atrial fibrillation or standstill. During
Electrocardiography
The ECG is a universally available and commonly used screening test in cardiology (Fig. 1). The resting 12-lead ECG is a useful tool for determining if cardiac involvement is present and often suggests the severity of such involvement in the majority of neuromuscular diseases. It is able to assess noninvasively the underlying cardiac rhythm, the integrity of AV conduction and intraventricular conduction, the presence of transient, ectopic beats and rhythms, and chamber enlargement. Ambulatory
Cardiac imaging studies
Imaging studies provide a noninvasive, detailed evaluation of cardiac function. Radiographic studies, such as radionuclide angiography, are able to assess ventricular size, function, wall motion, and myocardial perfusion. Cardiac ultrasonography, or echocardiography, also can estimate ventricular function but, in addition, can quantitatively assess atrial and ventricular dimensions and myocardial wall thickness, detect regional wall motion abnormalities resulting from areas of myocardial
Electrophysiologic testing
Invasive electrophysiologic (EP) testing provides a detailed evaluation of intracardiac conduction and assesses the risk and potential for arrhythmias. Many of the neuromuscular diseases manifest their cardiac involvement primarily with arrhythmias. Precise anatomic location of the site of conduction delay or block can be determined using specialized intracardiac catheters capable of measuring and delivering electrical stimuli. In general, conduction abnormalities within the AV node typically
Management of cardiac involvement
Diagnostic evaluation and therapy for cardiac involvement resulting from neuromuscular diseases should be aimed at determining the type and degree of involvement, limiting progression of underlying cardiac dysfunction, treating symptoms of congestive heart failure, and preventing complications from rhythm disturbances, such as bradycardia and tachycardia, mainly through device implantation. Despite the paucity of evidence regarding management of cardiac involvement in these disorders,
Neurology referral to cardiology
The timing of cardiology referral should be based on the presence of cardiac involvement and symptoms. Patients who have one of the neuromuscular diseases and an abnormal ECG should be referred to a cardiologist for further evaluation, even in the absence of cardiac symptoms. Those who have imaging abnormalities, such as LV dilatation, dysfunction, or regional wall motion abnormalities, also should be referred. The occurrence of symptoms as a result of congestive heart failure (dyspnea,
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