Mechanism of Typical Atrial Flutter in a Patient After Cardiac Transplant: Functional Slowing From Geometric Distortion.

BACKGROUND

Atrial flutter and atrial fibrillation occur after orthotopic heart transplant (OHT) in 25% of patients. Hemodynamic and medication restrictions in this unique population limit treatment.

CASE SUMMARY: A patient experienced prolonged episodes of paroxysmal atrial flutter and hypotension 8 days after OHT. Electrophysiology study demonstrated typical cavotricuspid isthmus (CTI)-dependent flutter, with slowing at the CTI midportion. Intracardiac echocardiography revealed that this site was distant from any suture lines or anastomoses. The slowing appeared to be secondary to geometric distortion (ie, "buckling" of the atrial wall) of the CTI.

DISCUSSION: Typical atrial flutter caused by functional slowing from structural distortion is distinct from prior reports of atrial flutter attributed to conduction block from suture lines. Computational models support the hypothesis that tissue curvature changes can lead to altered atrial conduction properties.

TAKE-HOME MESSAGE: Functional slowing from geometric distortion should be considered as a cause of atrial flutter in the post-OHT setting.