Paroxysmal supraventricular tachycardia (PSVT) is accompanied by hypotension, which can affect vascular hemodynamics. Here, we hypothesized that a fall in blood flow as a result of hypotension has a larger effect on hemodynamics in medium-sized peripheral arteries as compared to increased pulsatility in rapid pacing. To test this hypothesis, we experimentally and theoretically investigated hemodynamic changes in femoral, carotid and subclavian arteries at heart rates of 95-170 beats per minute (bpm) after acute pacing. The arterial pressure, blood flow and other hemodynamic parameters remained statistically unchanged for heart rates ≤ 135 bpm. Systemic pressure and flow velocities, however, showed an abrupt decrease resulting in larger alteration of hemodynamic parameters for heart rates ≥ 155 bpm after pacing (initial period) and then recovered close to baseline after several minutes of pacing (recovery period). During the initial period, the pressure dropped from 88 mmHg (baseline) to 44 mmHg and the flow velocity decreased to about 1/3 of baseline at heart rate of 170 bpm. A hemodynamic analysis showed a velocity profile with a near-wall retrograde flow or a fully-reversed flow during the initial period, which vanished at the recovery period. It was concluded that the initial fall of blood flow due to pressure drop led to transient flow reversal and negative wall shear stress because this phenomena was not observed at the recovery period. This study underscores the significant effects of hypotension on vascular hemodynamics which may have relevance to physiology and chronic pathophysiology in PSVT.
- flow reversal
- wall shear stress
- Copyright © 2010, Journal of Applied Physiology