[Aortic input impedance in ventricular septal defect].
Aortic input impedance and hydraulic power were measured in patients with ventricular septal defect (VSD). Aortic input impedance consists of the characteristic impedance (index of aortic distensibility) and the terminal impedance (index of peripheral resistance) which represent the left ventricular hydraulic load. The external left ventricular hydraulic power consists of steady power which transmits blood to the peripheral vasculature and pulsatile power which is converted into heat energy. The ratio of pulsatile to total power indicates the efficiency of the arterial system. The present study was carried out on 6 patients with VSD whose Qp/Qs was greater than 2.0 (VSD group) and 10 age-matched controls who had a history of Kawasaki disease without coronary complications at the time of cardiac catheterization (control group). Descending aortic pressure and flow velocity were measured simultaneously at the level of the 10th thoracic vertebra using a multisensor-catheter. Impedance data were calculated from Fourier analysis of these findings. Characteristic impedance did not differ between the 2 groups. Terminal impedance was higher in the VSD group with the increasing peripheral resistance and vascular afterload. The pulsatile component of external hydraulic power was similar in both groups, however, the steady component was lower in the VSD group indicating a higher ratio of pulsatile to total power in the VSD group. In conclusion, vascular afterload was increased and the efficiency of the arterial system was reduced in patients with VSD having large shunts.
Endo
H
H
Department of Pediatrics, Jichi Medical School, Tochigi.
Ichihashi
K
K
Kuramatsu
T
T
Shiraishi
H
H
Yano
S
S
Yanagisawa
M
M
Yaginuma
Y
Y
D001011:Aorta / Q000503:physiopathology*; D001783:Blood Flow Velocity / Q000502:physiology; D002675:Child, Preschool; D006345:Heart Septal Defects, Ventricular / Q000503:physiopathology*; D006439:Hemodynamics; D006801:Humans; D007223:Infant; D009080:Mucocutaneous Lymph Node Syndrome / Q000503:physiopathology; D010992:Plethysmography, Impedance; D011652:Pulmonary Circulation