A not so benign atrial flutter: spontaneous 1:1 conduction of atrial flutter

Abstract

SUMMARYA 1:1 conduction of atrial tachyarrhythmias, although not uncommon, usually is associated with the use of antiarrhythmic drugs; hyperthyroidism etc. Spontaneous 1:1 conduction of atrial flutter is indeed rare. We present a case of a spontaneous 1:1 conduction of a cavotricuspid isthmus-dependent atrial flutter. CASE PRESENTATIONA 50-year-old healthy man presented to an outside hospital with sudden onset of palpitations that lasted about 2 min before resolving on its own. It was associated with lightheadedness and dizziness. He denied any chest pain, shortness of breath and oedema. He reported two similar episodes in the past that resolved spontaneously, one of which occurred in the middle of the night lasting for 15 min and the other lasting for 2 min. A 12-lead ECG and telemetry were obtained. He was found to have atrial fibrillation with rapid ventricular rate around 150 bpm and atrial flutter (AFL) with 1:1 conduction at a rate approximately 280 bpm. He was diagnosed to have AFL with 1:1 conduction, he was treated with diltiazem infusion which cardioverted him to a normal sinus rhythm of around 70 bpm. He was transferred to our facility for further management.His history was otherwise unremarkable; there were no recent illness or change in his health habits. Blood tests ruled out an acute coronary syndrome, his thyroid function tests were within normal limits. A two-dimensional echocardiogram showed a normal functioning of the left ventricle with a normal-sized left atrium. A bicuspid aortic valve with mild aortic insufficiency was also noted. He remained in normal sinus rhythm throughout his hospital stay. He was discharged on β-blockers and aspirin.Subsequent electrophysiology testing was able to elicit only atrial fibrillation on atrial stimulation that was cardioverted. His HV interval was recorded at 44 ms, multiple attempts to induce AFL failed. Nonetheless, patient underwent cavotricuspid isthmus flutter ablation, as clinically his tachycardia matched AFL; moreover, it was felt that with a 1:1 conduction, it was better to ablate his tachycardia. He did well postprocedure, and has since remained symptom free.

Diagnosis and Management of 1:1 Atrial Flutter in the Setting of Aortic Valve Endocarditis and Embolic Stroke

“…Spontaneous 1:1 conduction of atrial flutter is indeed rare. Capturing a 1:1 atrial flutter outside controlled settings (e.g., electrophysiology [EP] labs) is very rare, and, thus, it is usually underdiagnosed as a possible cause of hemodynamic instability [16,17]. In our patient's case, it is possible that there was inflammation around the aortic valve area and the edema spread to the surrounding structures such as the AV node, which, in turn, blocked the AV node, allowing the concealed accessory pathways to become the primary pathway to the His-Purkinje system, thus allowing 1:1 conduction.…”