[Impaired cardiopulmonary baroreflex control of forearm vascular resistance in hypertrophic cardiomyopathy].
We tested the hypothesis that the cardiopulmonary baroreflex control of forearm vascular resistance is impaired in patients with hypertrophic nonobstructive cardiomyopathy (HNCM). Forearm vascular responses to lower body negative pressures (LBNP) at -20 mmHg and -40 mmHg and to lower body positive pressure (LBPP) at +20 mmHg and +40 mmHg were compared between 11 patients with HNCM and 6 normal subjects. Forearm blood flow was measured with a strain gauge plethysmograph and forearm vascular resistance was calculated by dividing mean blood pressure by forearm blood flow. The left ventricular end-diastolic dimension and the left atrial dimension changed with the increases in LBNP and LBPP in patients with HNCM and in normal subjects. The ranges of these changes were similar in the 2 groups. Mean blood pressure and heart rate did not change during LBNP and LBPP. LBNP increased but LBPP decreased forearm vascular resistance in normal subjects, but neither LBNP nor LBPP changed the resistance in patients with HNCM. Increases in the resistance to cold pressor tests did not differ between the 2 groups. In patients with HNCM, there was a negative correlation between forearm vascular resistance at LBNP -20 mmHg and the left ventricular wall thickness (r = -0.81, p < 0.01). These results suggest that the cardiopulmonary baroreflex control of forearm vascular resistance is impaired in hypertrophic cardiomyopathy and that this impairment may be associated with left ventricular wall thickness.
Nishian
K
K
First Department of Internal Medicine, Hyogo College of Medicine, Nishino-miya.
Kawashima
S
S
Kondo
T
T
Tateishi
J
J
Fujitani
K
K
Iwasaki
T
T
D000328:Adult; D002312:Cardiomyopathy, Hypertrophic / Q000503:physiopathology*; D005260:Female; D005542:Forearm / Q000098:blood supply*; D006321:Heart / Q000294:innervation; D006801:Humans; D008150:Lower Body Negative Pressure; D008168:Lung / Q000294:innervation; D008297:Male; D008875:Middle Aged; D011311:Pressoreceptors / Q000503:physiopathology*; D012018:Reflex / Q000502:physiology; D014655:Vascular Resistance