Abstract 518: Hemodynamic Instability in Atrial Flutter With Slow Ventricular Response

Abstract

Background: The commonest atrioventricular (AV) conduction ratio in atrial flutter is 2:1, with corresponding ventricular response of about 150 beats/min. Higher degree of AV block with resulting lower ventricular conduction may indicate use of AV nodal blocking drugs, intrinsic conducting system disease, electrolyte abnormalities or hypothermia. Case: An 86-year-old with history of hypertension, hyperlipidemia, hypothyroidism, coronary and carotid artery disease was admitted after a syncopal episode while on a cross country trip. He was hypotensive and profoundly bradycardic(heart rate initially in the 30s). Examination revealed irregular rhythm and right carotid bruit. EKG showed atrial flutter with variable ventricular response ranging from 3:1 to 5:1 (or more) block, with ventricular rate in the 50s and 60s. Echocardiogram showed low normal left ventricular systolic function without regional wall abnormalities, right ventricle enlargement with global systolic dysfunction, and severe left atrial enlargement. Thyroid function was normal. Decision-making: With hemodynamic instability in the setting of atrial flutter, he was started on anticoagulation and intravenous hydration, and after left atrial thrombus was ruled out with a transesophageal echocardiogram, he underwent successful urgent cardioversion. He was then noted to have intermittent Mobitz type II second degree and third degree AV block, prompting urgent temporary transvenous pacemaker (PM) placement, followed by permanent dual chamber PM implantation. He had bleeding from the PM placement site but this was controlled with pressure. Therapy with beta blocker was re-initiated, and electrolytes were supplemented as needed. Vitals signs improved and he was discharged in stable health to follow up with his cardiologist. Conclusion: Urgent or emergent cardioversion is indicated for hemodynamic instability in atrial flutter, even with slow ventricular response. In the absence of use of AV nodal blocking agents, lower rate of ventricular response may indicate intrinsic conducting system disease, and as in the case above, may require PM placement.