Isobe Satoshi, Izawa Hideo, Iwase Mitsunori, Nanasato Mamoru, Nonokawa Makoto, Ando Akitada, Ohshima Satoru, Nagata Kohzo, Kato Katsuhiko, Nishizawa Takao, Murohara Toyoaki, Yokota Mitsuhiro
Department of Cardiology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi 466-8550, Japan.
J Nucl Med. 2005 Jun;46(6):909-16.
Little is known about the relation between left ventricular (LV) functional reserve in response to exercise and cardiac sympathetic nervous function in patients with nonobstructive hypertrophic cardiomyopathy (HCM). We investigated whether an assessment of cardiac sympathetic nervous function by myocardial (123)I-metaiodobenzylguanidine ((123)I-MIBG) scintigraphy might provide a sign of an abnormal LV functional reserve in response to exercise-induced beta-adrenergic stimulation in patients with HCM.
Thirty HCM patients underwent (123)I-MIBG scintigraphy and echocardiography at rest and subsequent biventricular cardiac catheterization at rest and during dynamic exercise. LV pressures were measured using a micromanometer-tipped catheter system. The early and delayed (123)I-MIBG images were quantified as a heart-to-mediastinum ratio (H/M). The plasma levels of brain natriuretic peptide (BNP) and norepinephrine (NE) were also measured.
Patients were divided into 2 groups according to the delayed (123)I-MIBG H/M: group I consisted of 12 patients with a delayed H/M of < or =1.8 and group II had 18 patients with a delayed H/M of >1.8. Both the percentage increase from rest to exercise in LV isovolumic contraction (LV dP/dt(max)) and the percentage shortening of LV pressure half-time (T(1/2)) as an index of isovolumic relaxation were significantly less in group I than in group II (P < 0.05, respectively). A significant linear correlation was observed between the percentage increase in LV dP/dt(max) and (123)I-MIBG H/Ms (early H/M: r = 0.49, P < 0.01; delayed H/M: r = 0.54, P < 0.005, respectively). A significant linear correlation was also observed between the percentage shortening in T(1/2) and (123)I-MIBG H/Ms (early H/M: r = 0.58, P < 0.001; delayed H/M: r = 0.64, P < 0.0005, respectively). The plasma NE levels were significantly higher in group I than in group II (P < 0.01), whereas the plasma BNP levels were comparable in the 2 HCM groups.
beta-Adrenergic enhancement of LV function during exercise may depend on the extent of cardiac sympathetic nervous innervation in HCM patients. Resting myocardial (123)I-MIBG scintigraphy can noninvasively evaluate LV functional reserve in response to exercise in patients with nonobstructive HCM.
关于非梗阻性肥厚型心肌病（HCM）患者运动时左心室（LV）功能储备与心脏交感神经功能之间的关系，目前所知甚少。我们研究了通过心肌（123）I-间碘苄胍（（123）I-MIBG）闪烁显像评估心脏交感神经功能，是否能为HCM患者运动诱导的β-肾上腺素能刺激下左心室功能储备异常提供迹象。
30例HCM患者在静息状态下接受（123）I-MIBG闪烁显像和超声心动图检查，随后在静息和动态运动期间进行双心室心导管检查。使用微测压导管系统测量左心室压力。早期和延迟的（123）I-MIBG图像以心/纵隔比（H/M）进行量化。还测量了血浆脑钠肽（BNP）和去甲肾上腺素（NE）水平。
根据延迟的（123）I-MIBG H/M将患者分为2组：I组由12例延迟H/M≤1.8的患者组成，II组有18例延迟H/M>1.8的患者。I组从静息到运动时左心室等容收缩（LV dP/dt（max））的增加百分比以及作为等容舒张指标的左心室压力半衰期（T（1/2））缩短百分比均显著低于II组（P均<0.05）。观察到LV dP/dt（max）增加百分比与（123）I-MIBG H/M之间存在显著线性相关性（早期H/M：r = 0.49，P < 0.01；延迟H/M：r = 0.54，P < 0.005）。T（1/2）缩短百分比与（123）I-MIBG H/M之间也观察到显著线性相关性（早期H/M：r = 0.58，P < 0.001；延迟H/M：r = 0.64，P < 0.0005）。I组血浆NE水平显著高于II组（P < 0.01），而两个HCM组的血浆BNP水平相当。
运动期间LV功能的β-肾上腺素能增强可能取决于HCM患者心脏交感神经支配的程度。静息心肌（123）I-MIBG闪烁显像可无创评估非梗阻性HCM患者运动时的左心室功能储备。
