A case report of profound atrioventricular block in an endurance athlete: how far do you go?

Background: Athletes presenting with 1st-degree atrioventricular block (AVB) on 12-lead electrocardiogram (ECG) may present a diagnostic conundrum, especially when significantly prolonged and associated with higher degrees of block. A pragmatic stepwise approach to the evaluation of these patients is, therefore, crucial. Case summary: A 19-year-old waterpolo player was referred for assessment of a 1st-degree heart block and one isolated episode of syncope. All other cardiac investigations were within normal limits except for a 24-h ambulatory ECG which showed Mobitz 1 AVB and episodes of 2:1 block occurring in the context of Wenchebach. An electrophysiological study (EPS) was performed which effectively excluded infranodal conductive tissue disease, confirming physiological intranodal block. Discussion: The increase in vagal tone is one of the physiological adaptations to an increased demand in cardiac output in athletes, which explains the presence of 1st-degree AVB in up to 7.5% of athletes. The presence of 2:1 AVB on 24 h ECG raises doubts whether the 1st-degree AVB on resting ECG is pathological or physiological, especially considering this particular patient had suffered an episode of syncope. When this diagnostic uncertainty persists despite non-invasive investigations, including cardiopulmonary exercise testing, invasive EPS may be required to assess the refractoriness of the AV node and at what level within the cardiac conductive system block occurs. The electrophysiological study can effectively rule out infranodal disease by confirming physiological intranodal block using incremental atrial pacing.

Congenitally corrected transposition of the great arteries (CCTGA).

A 33-year-old man presented with a 3-week history of breathlessness and cough. He disclosed that he was informed regarding a heart defect as a child in his home country but was unaware of its nature and was never followed up. Examination revealed a pansystolic murmur (loudest at the apex), a hyperdynamic, displaced apex, and pulmonary oedema. An ECG showed atrial fibrillation with a regular broad-complex ventricular rhythm. Following electrical cardioversion, the ECG revealed complete heart block, therefore explaining the regular atrial fibrillation. An urgent transthoracic echocardiography (TTE) confirmed the anatomy of congenitally corrected transposition of the great arteries (CCTGA) with torrential tricuspid regurgitation and impaired systemic right ventricle. Cardiac MRI identified a ventricular septal defect which was not visible on TTE. The patient showed a transient improvement following fluid offloading and ACE inhibition, with a more definitive improvement after cardiac resynchronisation therapy (CRT).

Cobalt Cardiomyopathy Secondary to Hip Arthroplasty: An Increasingly Prevalent Problem.

A forty-year-old man experienced worsening heart failure four years following bilateral complicated total hip replacement. His condition was extensively worked up but no underlying pathology was immediately evident. Given the cobalt-chromium alloy component present in the hip arthroplasties, the raised cobalt blood levels, and a fitting clinical picture coupled with radiological findings, the patient underwent right hip revision. Evidence of biotribocorrosion was present on direct visualisation intraoperatively. The patient subsequently experienced symptomatic improvement (NYHA class III to class I) and echocardiography showed recovery of ejection fraction. Cobalt exists as a bivalent and trivalent molecule in circulation and produces a cytotoxicity profile similar to nanoparticles, causing neurological, thyroid, and cardiological pathology. Blood levels are not entirely useful as there is no identifiable conversion factor for levels in whole blood, serum, and erythrocytes which seem to act independently of each other. Interestingly cobalt cardiomyopathy is frequently compounded by other possible causes of cardiomyopathy such as alcohol and a link has been postulated. Definitive treatment is revision of the arthroplasty as other treatments are unproven.

Broken heart during treadmill exercise testing: an unusual cause of ST-segment elevation.

Treadmill exercise testing is a commonly used diagnostic test for the assessment of chest discomfort and exercise-induced arrhythmias. The presence of ST-segment elevation during exercise is considered a marker of severe ischaemia, usually secondary to a critical lesion in a proximal coronary artery. We present a novel cause of ST-segment elevation during exercise testing: "broken heart syndrome", also known as transient left ventricular apical ballooning syndrome, or takotsubo cardiomyopathy. Takotsubo cardiomyopathy is a rare, yet well-described, reversible cardiomyopathy triggered by profound psychological or physical stress. The exact aetiology of takotsubo cardiomyopathy is still unknown. However, the occurrence of takotsubo cardiomyopathy during exercise in this case report is in keeping with the sudden catecholamine surge secondary to treadmill exercise testing, which leads to abnormal ventricular contraction and contributes to wall motion abnormalities. Further studies are needed to elucidate the pathogenesis of the disease and consequently determine specific preventive therapies.

Coronary artery air embolism causing pulmonary edema secondary to acute coronary syndrome in a diver.

Air embolism in the coronary arteries is a known complication of coronary angiography. Diving is a non-iatrogenic cause of arterial air embolism, commonly presenting with neurological and musculoskeletal symptoms. This is the first known case of coronary air embolism confirmed on coronary angiography in a diver presenting with pulmonary edema secondary to acute coronary syndrome. The possible mechanisms of coronary air embolism during a dive are reviewed in this article.