A case of left ventricular outflow tract obstruction detected after transcatheter aortic valve implantation

Excerpt

A woman in her 80s with a history of hypertension presented with exertional dyspnea. On auscultation, systolic ejection murmur was loudest in the second intercostal space at the right sternal border. Transthoracic echocardiography(TTE) showed: left ventricular (LV) end-diastolic dimension, 44 mm; LV end-systolic dimension, 22 mm; interventricular septum thickness, 16 mm; posterior wall thickness, 11 mm; LV hypertrophy; C-sept distance, 12.3 mm; asymmetric septal hypertrophy (ASH); and systolic anterior motion (SAM) of the mitral valve (Fig. 1a). LV outflow tract (LVOT) diameter was small (18.2 mm), and LV ejection fraction was 81%. Color Doppler imaging showed a mosaic blood flow signal pattern in the LVOT (Fig. 1b). Continuous wave Doppler (CWD) showed a backward shift of the peak, LVOT flow velocity of 2.7 m/s (maximum pressure gradient [PG], 29 mmHg), and accelerated blood flow (Fig. 1c). Severe aortic valve calcification prevented full valve opening, and transesophageal echocardiography with CWD indicated high peak aortic valve flow velocity (5.9 m/s) and mean PG (69 mmHg) (Fig. 1d). The aortic valve area was 0.93 cm² (Planimetry method), revealing severe aortic stenosis (AS). Transcatheter aortic valve replacement (TAVR) was performed with an Evolut R 26 mm valve. On postoperative day 1, TTE showed exacerbation of LVOT flow velocity; by day 5, SAM of the mitral valve (Fig. 2a) and worsened LVOT blood flow was observed (5.9 m/s; maximum PG, 140 mmHg) (Fig. 2b, c). Nine days after administering bisoprolol 2.5 mg/day and cibenzoline 100 mg/day, TTE showed improvement of SAM (Fig. 3a). Color Doppler revealed improvement of the mosaic blood flow signal pattern in the LVOT (Fig. 3b) and flow velocity (2.0 m/s; maximum PG, 16 mmHg) (Fig. 3c). Risk factors for accelerated LV blood flow exacerbation after TAVR include small LVOT diameter, preoperative accelerated LV blood flow, and fast aortic valve flow velocity [1]. In patients with AS, 22% have ASH (like our patient) [2], but few reports exist of TAVR with severe AS and coexisting SAM or of improving postoperative LVOT obstruction by medical therapy alone, as in our patient. Effective treatments include calcium antagonists, bisoprolol, and cibenzoline [3, 4]. Another effective approach for concurrent AS and accelerated LV blood flow is to use oral β-blockers before surgery and then determining the overall treatment strategy [5]. When undergoing TAVR, patients with SAM, accelerated LVOT blood flow, or small LVOT diameter need to be monitored carefully. This case demonstrates that TTE is useful for diagnosis and evaluating treatment efficacy.

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