内田 文也¹, 笠井 篤信², 安田 正樹², 大道 近也², 藤井 英太郎², 浜中 恵子¹

Fumiya UCHIDA¹, Atsunobu KASAI², Masaki YASUDA², Chikaya OMICHI², Eitarou FUJII², Keiko HAMANAKA¹

¹松阪市民病院中央検査科生理検査室, ²松阪市民病院内科

¹Department of Clinical Laboratory, Matsusaka City Hospital, ²Department of Cardiology, Matsusaka City Hospital

キーワード : Color kinesis, DDD pacing, Echocardiography, Hypertrophic obstructive cardiomyophathy

Dual-chamber (DDD) pacing has been reported to reduce left ventricular outflow tract (LVOT) pressure gradient and improve drug-refractory symptoms in patients with hypertrophic obstructive cardiomyopathy (HOCM). Here we report the case of a 68-year-old woman who complained of chest discomfort at rest, and whose discomfort was relieved by implantation of a DDD device. A two-dimensional echocardiogram showed diffuse severe left ventricular hypertrophy of all except the posterobasal wall, and an M-mode echocardiogram of the mitral valve showed mild systolic anterior motion (SAM). LVOT pressure gradient, estimated with continuous-wave Doppler examination, was 89 mmHg. These findings were compatible with HOCM of Maron classification Ⅲ. On cardiac catheterization, LVOT pressure gradient during AAI pacing was 69 mmHg but fell to 57 mmHg during DDD pacing with an 80-msec A-V delay. Color kinesis imaging in a two-dimensional echocardiogram obtained during DDD pacing showed that preexcitation and contraction of the left ventricular apex, and delayed contraction of the left ventricular mid portion and LVOT prevented obstruction. Although the magnitude of SAM decreased, paradoxical motion of the interventricular septum did not. Color kinesis imaging provides another noninvasive method of evaluating the left ventricular contraction sequence, and its findings suggest that reduction in LVOT pressure gradient during DDD may account for preexcitation and contraction of the left ventricular apex.