Diurnal variation of hemodynamic indices in non-dipper hypertensive patients.
The purpose of this study was to elucidate the underlying mechanisms of blunted nocturnal blood pressure reduction in non-dipper hypertensive patients. We studied the diurnal variations in systemic hemodynamic indices and baroreflex sensitivity. In 45 subjects with essential hypertension (24 men; mean age, 49+/-1 years), intra-arterial pressure was monitored telemetrically. Non-dippers were defined as those with a nocturnal reduction of systolic blood pressure of less than 10% of daytime systolic blood pressure. Stroke volume was determined using Wesseling's pulse contour method, calibrated with indocyanine green dilution. Baroreflex sensitivity was calculated as deltapulse interval/deltasystolic blood pressure on spontaneous variations. The mean values of the hemodynamic parameters were calculated every 30 min. Twenty-six subjects were classified as non-dippers. Daytime blood pressure was not significantly different between dippers (149+/-4/87+/-3 mmHg) and non-dippers (147+/-3/82+/-2 mmHg), while the nighttime blood pressure was significantly reduced in dippers (131+/-3/77+/-2 mmHg) but not in non-dippers (145+/-3/80+/-2 mmHg). Nocturnal decreases in both cardiac index and stroke index were smaller in non-dippers (-12.0+/-1.2% and 1.5+/-1.0%) than in dippers (-17.5+/-1.4% and -2.2+/-1.1%). Baroreflex sensitivity significantly increased at nighttime both in dippers (6.5+/-0.6 to 8.0+/-0.7 ms/mmHg) and in non-dippers (5.1+/-0.3 to 6.4+/-0.4 ms/mmHg). Neither daytime nor nighttime baroreflex sensitivity was significantly different between the groups. We conclude that the hemodynamics of non-dipper essential hypertension are characterized by an inadequate nocturnal decrease in cardiac index and stroke index, suggestive of relative volume expansion or malsuppressed sympathetic activity.
Takakuwa
H
H
Department of Internal Medicine, School of Medicine, Kanazawa University, Japan. takakuwa@medf.m.kanazawa-u.ac.jp
Ise
T
T
Kato
T
T
Izumiya
Y
Y
Shimizu
K
K
Yokoyama
H
H
Kobayashi
K I
KI
D000328:Adult; D017704:Baroreflex / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology*; D018660:Blood Pressure Monitoring, Ambulatory; D001810:Blood Volume / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011674:Pulse; D013564:Sympathetic Nervous System / Q000503:physiopathology