Atrioventricular (AV) block is an AV conduction disorder that can manifest in various settings, with varying symptomaticity and severity. The electrocardiogram is a key diagnostic tool for management, and careful interpretation is necessary to institute the correct management. We described two cases of patients with bradycardia due to AV blocks and discussed the electrocardiogram interpretation and management.

Sarcoidosis is a multisystem granulomatous disease predominantly affecting the lungs, with increased risk of cardiovascular disease, pulmonary hypertension and cardiac sarcoidosis (CS), the latter due to direct granuloma infiltration. Sarcoidosis is often managed by chest physicians who need to understand the diagnostic pathways and initial management plans for patients with cardiac involvement. Areas covered: The most serious consequence of CS is sudden cardiac death due to ventricular tachyarrhythmias or complete atrioventricular block. Additional complications include atrial arrhythmias and congestive cardiac failure. There are no internationally accepted screening pathways, but a combination of history, clinical examination and ECG detects up to 85% of cases. Newer modalities including signal averaged ECG and speckle-tracking echocardiography increase identification of patients who require a definitive diagnosis. Early immunosuppression reduces the risk of conduction abnormalities and incidence of supraventricular arrhythmias. Management of ventricular arrhythmias requires antiarrhythmic medications followed by possible catheter ablation and device (ICD) implantation. Expert Commentary: Prospective trials are underway to identify the optimum methods for screening, which will guide future international statements on indications for and methods of screening in CS.

Hyponatremia is the most common electrolyte disorder among hospitalized patients and in the clinical setting. Patients with hyponatremia may develop a variety of symptoms, primarily neurological and gastrointestinal. Hyponatremia is more frequently encountered in patients with an underlying heart disease, particularly in the elderly. We hereby present a case of complete atrioventricular block in an elderly patient who had undergone aortic valve replacement and had been using thiazide. Complete atrioventricular block improved after sodium replacement therapy and no other cause of electrolyte disorder was documented.

An 82-year-old man with a history of coronary artery bypass surgery, hypertension and small bowel gastrointestinal stromal tumour underwent cardiac risk evaluation prior to surgical resection of his tumour. He was asymptomatic from a cardiovascular perspective, but his activity level was less than four metabolic equivalents. Physical examination was notable for a 2/6 systolic murmur at the apex. ECG showed sinus rhythm. A transthoracic echocardiogram was performed (figure 1 and online supplementary video 1).DC1SP110.1136/heartjnl-2018-313413.supp1Supplementary file 1 heartjnl;heartjnl-2018-313413v1/F1F1F1Figure 1Transthoracic echocardiography. (A) Mitral valve continuous wave Doppler and (B) tricuspid valve continuous wave Doppler.

A 16-year-old male presented with an orthodromic atrioventricular reentrant tachycardia over a concealed parahisian accessory pathway (AP). Cryoablation of the AP resulted in transient manifestation of a fully preexcited sinus rhythm of parahisian AP morphology. Potential causes for the paradoxical preexcitation include inadvertent atrioventricular nodal block, sourse-sink mismatch, as well as the activation of a dormant AP capable of anterograde conduction. This article is protected by copyright. All rights reserved.