An Unusual Case of Left Ventricular Outflow Tract Obstruction after Aortic Valve Replacement

Surgical valve replacement improves the symptoms and prognosis of patients with valvular heart diseases. Aortic regurgitation elicits volume overload that causes enlargement of the left ventricle (LV), while the LV size often shrinks to near normal after aortic valve replacement (AVR), which is referred to as "reverse remodeling". We experienced a case in which LV outflow tract (LVOT) obstruction became apparent after AVR, resulting in worsening of heart failure. A 65-year-old man who had undergone surgical AVR for aortic valve regurgitation 15 months previously exhibited dyspnea on effort accompanied with severe LVOT obstruction. With double pressure catheters, we directly recorded an augmented pressure gradient in the LVOT and rapid relief of the obstruction by intravenous administration of the anti-arrhythmic drug cibenzoline. Since the considerable LV hypertrophy had been indicated by an electrocardiogram and echocardiography before AVR, we suspected that dilation of the LV chamber due to aortic valve regurgitation could have masked the subclinical LVOT obstruction, which became clinically evident after LV size reduction due to reverse remodeling after AVR.