Malviya Amit, Khan Shakeel A, Gupta Anunay, Mishra Animesh
Cardiology, North Eastern Indira Gandhi Regional Institute of Health and Medical Sciences, Shillong, IND.
Cardiology, Vardhman Mahavir Medical College and Safdarjung Hospital, New Delhi, IND.
Cureus. 2021 Jul 6;13(7):e16202. doi: 10.7759/cureus.16202. eCollection 2021 Jul.
Cannabis usage is increasing throughout the world for both medicinal and recreational purposes. Several countries and states have legalized cannabis, and physicians can expect to encounter more patients who use or abuse cannabis. Adverse cardiovascular effects of cannabis like myocardial infarction, cardiomyopathy, and arrhythmias have been well described but bradyarrhythmia is rare and the mechanisms are not well pronounced. A 26-year-old male with a history of chronic cannabis smoking presented with complaints of dizziness and recurrent syncope. The heart rate at presentation was 42 beats per minute and the rest of the physical examination was unremarkable. There was an atrioventricular (AV) block in the ECG and a subsequent electrophysiological study (EPS) showed a high-grade supra-Hisian (nodal) AV block with prolonged His-ventricular (HV) interval. The urinary screen was positive for tetrahydrocannabinol metabolite (11-Nor-9-carboxy THC). After ruling out other possible causes, a diagnosis of high-grade AV block due to chronic cannabis use was made. A dual-chamber pacemaker was implanted and the patient was discharged in stable condition. The arrhythmia did not improve completely at the three-month follow-up. We report a novel finding in cannabis-induced bradyarrhythmia. High-grade AV block with the electrophysiologic determination of the site of conduction blockade has not been reported previously. The mechanism of bradyarrhythmia is thought to be mediated by increased vagal tone. However, prolonged HV interval and persistent nature of block indicate that direct toxic effects of cannabis, through cannabinoid receptors 1 (CB1R), on the cardiac conduction system cannot be ruled out. Also, the possibility of cannabis arteritis involving microvasculature should be kept.
出于医疗和娱乐目的，大麻在全球的使用量都在增加。几个国家和州已将大麻合法化，医生可能会遇到更多使用或滥用大麻的患者。大麻对心血管的不良影响，如心肌梗死、心肌病和心律失常，已有详细描述，但缓慢性心律失常很少见，其机制也不太明确。一名有慢性吸食大麻史的26岁男性，主诉头晕和反复晕厥。就诊时心率为每分钟42次，其余体格检查无异常。心电图显示存在房室传导阻滞，随后的电生理研究（EPS）显示为高度希氏束上（结性）房室传导阻滞，希氏束-心室（HV）间期延长。尿液筛查四氢大麻酚代谢物（11-去甲-9-羧基四氢大麻酚）呈阳性。排除其他可能原因后，诊断为慢性大麻使用导致的高度房室传导阻滞。植入了双腔起搏器，患者出院时病情稳定。在三个月的随访中，心律失常并未完全改善。我们报告了大麻所致缓慢性心律失常的一项新发现。此前尚未报道过通过电生理确定传导阻滞部位的高度房室传导阻滞。缓慢性心律失常的机制被认为是由迷走神经张力增加介导的。然而，HV间期延长和阻滞的持续性表明，大麻通过大麻素受体1（CB1R）对心脏传导系统的直接毒性作用也不能排除。此外，还应考虑大麻动脉炎累及微血管的可能性。
