BJSM Table 1. Abnormal ECG findings suggestive of cardiomyopathy Abnormal ECG finding Definition T wave inversion >1 mm in depth in two or more leads V2–V6, II and ST segment depression Pathological Q waves Complete left bundle branch block aVF or I and aVL (excludes III, aVR and V1) ≥0.5 mm in depth in two or more leads >3 mm in depth or >40 ms in duration in two or more leads (except III and aVR) QRS≥120 ms, predominantly negative QRS complex in lead V1 (QS or rS), and upright monophasic R wave in leads I and V6 Intraventricular conduction delay Left axis deviation Left atrial enlargement Any QRS duration ≥140 ms −30° to −90° Prolonged P wave duration of >120 ms in leads I or II with negative portion of the P wave≥1 mm in Right ventricular hypertrophy pattern Premature ventricular contractions Ventricular arrhythmias R-V1+S-V5>10.5 mm AND right axis deviation >120° ≥2 PVCs per 10 s tracing Couplets, triplets and non-sustained ventricular tachycardia Note: These ECG findings are unrelated to regular training or expected physiological adaptation to exercise, may suggest the presence of pathological cardiovascular disease, and require further diagnostic evaluation. rhythmias and sudden death. On histopathological analysis, disorganised cellular architecture with cardiac myocyte disarray is a hallmark feature.12 Prevalence HCM is among the most common inherited cardiovascular disorders and may occur in 1 : 500 adults and at equal prevalence in men and women.12 However, the reported prevalence of HCM in competitive athletes is apparently lower, approximately 1 in 1000 to 1 in 1500 athletes.3 14 HCMis inherited primarily as autosomal dominant with variable penetrance, and morphological expression of HCM may appear in childhood but typically develops in early adolescence through young adulthood. This may contribute to the lower prevalence of HCMfound in younger athletes. depth and ≥40 ms in duration in lead V1 Contribution as a cause of SCD In most case series, HCM is among the most common causes of SCD in young athletes. In the USA, HCM accounts for approximately one-third of identified causes of SCD in athletes, and in the UK HCM represents 11% of cases.1 15 HCM is a less common cause of sudden death in other populations. In US military personnel, HCM accounted for only 6% of SCD, and in the US general population (less than 35 years old) only 5% of cases of sudden cardiac arrest were attributed to HCM.16 17 other patterns of pathological hypertrophy are consistent with HCM such as apical hypertrophy, concentric hypertrophy and proximal septal hypertrophy. Poor ventricular compliance (diastolic dysfunction) is characteristic, along with microvascular dysfunction which contribute to ischaemia during exercise. Some patients have dynamic left ventricular (LV) outflow tract obstruction caused by the combination of hypertrophy and abnormalities of the mitral valve which leads to systolic anterior motion of the anterior leaflet. However, only about 25% of patients with HCM have a murmur from LV outflow tract obstruction during resting examination.12 pain, syncope and exercise intolerance, but for many persons the disease can be asymptomatic and SCD may be the clinical presentation of the disease.13 Fibrosis of the heart muscle is characteristic and may underlie ventricular ar28 Sport & Geneeskunde | juli 2013 | nummer 3 Diagnostic criteria HCM can be diagnosed by ECG in combination with echocardiography or cardiac MRI. An LV wall thickness of 1.5 cm or greater is normally required to make the diagnosis, but marked asymmetry with lower absolute wall thickness measurement is also compatible with HCM. The upper limit of normal wall thickness in most echocardiography laboratories is 1.2 cm. A ‘grey area’ is defined between 1.2 and 1.5 cm. In borderline cases, other features favouring a diagnosis of HCM include impaired diastolic function, small LV cavity size, LV wall thickness asymmetry, mitral valve pathology (leaflet redundancy and systolic anterior motion) and the presence of myocardial fibrosis (late gadolinium enhancement) on cardiac MRI.18 Symptoms of HCM include chest Abnormal ECG findings in HCM Over 90% of patients with HCM will have an abnormal ECG.19–21 ECG abnormalities include T wave inversion (TWI), ST segment depression, pathological Q waves, conduction delay, left-axis deviation (LAD) and left atrial enlargement (LAE). Pagina 27
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Sport & Geneeskunde nummer 3 | Juli 2013 Lees publicatie 24Home