Phasic aortic flow velocity in patients with pulsus alternans

Area of Science:

• Cardiovascular Physiology
• Hemodynamics
• Clinical Echocardiography

Background:

• Pulsus alternans is a rare cardiac arrhythmia characterized by alternating strong and weak heartbeats.
• The underlying mechanisms of pulsus alternans, particularly the variation in stroke volume, require further elucidation.

Purpose of the Study:

• To investigate the hemodynamic alterations in patients with pulsus alternans.
• To provide direct evidence of stroke volume variation in pulsus alternans.
• To explore potential underlying causes of stroke volume alternation.

Main Methods:

• Phasic aortic flow velocity was measured using a Doppler ultrasonic flowmeter system.
• Measurements were recorded in two patients diagnosed with pulsus alternans.
• Beat-to-beat peak velocity was analyzed in conjunction with arterial and ventricular systolic pressures.

Main Results:

• Phasic aortic flow velocity demonstrated significant beat-to-beat variations.
• These velocity variations directly correlated with changes in arterial and ventricular systolic pressures.
• The study provided direct evidence of fluctuating stroke volume during pulsus alternans.

Conclusions:

• Pulsus alternans is associated with demonstrable beat-to-beat stroke volume variations.
• The observed hemodynamic changes suggest an underlying mechanism possibly related to end-diastolic fiber length alternations.
• Further research is warranted to confirm the proposed mechanisms and their clinical implications.