Cardiac sympathetic activity in the asymmetrically hypertrophied septum in patients with hypertension or hypertrophic cardiomyopathy.
BACKGROUND
In patients with essential hypertension (HT), proportional (symmetric) left ventricular hypertrophy (LVH) is common. In contrast, hypertrophic cardiomyopathy (HCM) is characterized by disproportional LVH and, in particular, asymmetric septal hypertrophy (ASH); however, some hypertensive patients also develop ASH. It has not been determined whether such cases represent a distinct type of hypertensive LVH or HCM combined with hypertension.


OBJECTIVE
The study was undertaken to evaluate sympathetic activity in the interventricular septum in patients with HT and ASH or in patients with HCM.


METHODS
The patients were evaluated by I-123 meta-iodobenzylguanidine (MIBG) and thallium-201 (201Tl) single-photon emission computed tomography (SPECT), respectively. They were divided into three groups: patients with essential HT and symmetric septal hypertrophy (Group A), patients with HT and ASH (Group B), and patients with HCM and ASH (Group C).


RESULTS
Compared with the lateral wall, early uptake of MIBG in the septum was significantly higher in Group B than in Group A, but not significantly different between Groups A and C. Compared with the lateral wall, early uptake of 201Tl in the septum did not differ among the three groups. No significant difference in the MIBG clearance in the lateral wall was seen among the three groups. By contrast, MIBG clearances in the septum and apex were significantly greater in Group C than in Groups A and B. There was an inverse correlation between systolic thickening and MIBG clearance in the septum.


CONCLUSIONS
These findings suggest that sympathetic activity in the septum differs between patients with HT and ASH and patients with HCM.
Shimizu
M
M
The Second Department of Internal Medicine, School of Medicine, Kanazawa University, Japan.
Ino
H
H
Okeie
K
K
Emoto
Y
Y
Yamaguchi
M
M
Yasuda
T
T
Fujino
N
N
Fujii
H
H
Fujita
S
S
Nakajima
K
K
Taki
J
J
Mabuchi
H
H
D019797:3-Iodobenzylguanidine; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D001795:Blood Pressure Determination; D002312:Cardiomyopathy, Hypertrophic / Q000150:complications* / Q000000981:diagnostic imaging / Q000503:physiopathology*; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006346:Heart Septum / Q000000981:diagnostic imaging* / Q000294:innervation*; D006801:Humans; D006973:Hypertension / Q000150:complications*; D017379:Hypertrophy, Left Ventricular / Q000150:complications*; D008297:Male; D008875:Middle Aged; D011336:Probability; D019275:Radiopharmaceuticals; D012044:Regression Analysis; D012680:Sensitivity and Specificity; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D015899:Tomography, Emission-Computed, Single-Photon
D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine