Role of intra-ventricular vortex in left ventricular ejection elucidated by echo-dynamography

Area of Science:

• Cardiovascular Physiology
• Biomedical Engineering
• Echocardiography

Background:

• Understanding the intricate mechanisms of left ventricular (LV) blood ejection is crucial for diagnosing and treating cardiac conditions.
• The pre-ejection transitional period (pre-ETP) is a critical phase where initial blood flow dynamics are established.
• The role of intra-ventricular vortices in cardiac function remains an area of active investigation.

Purpose of the Study:

• To elucidate the ejection mechanisms of the left ventricle (LV) during the pre-ejection transitional period (pre-ETP).
• To detail the specific role of the intra-ventricular vortex in LV blood ejection.
• To correlate blood flow dynamics with LV wall dynamics using echo-dynamography.

Main Methods:

• Utilized echo-dynamography to analyze intra-ventricular flow structure in 10 healthy volunteers.
• Employed high-frame-rate two-dimensional echocardiography for measuring LV wall dynamics.
• Applied a developed phase difference tracking method to assess LV wall motion.

Main Results:

• Observed a large, accelerated vortex forming in the central basal area of the LV during the pre-ETP.
• Documented a linearly increasing pattern in the main flow axis velocity of the LV.
• Found that the vortex's centrifugal force contributed to a ~50% stepwise increase in ejection velocity.

Conclusions:

• Left ventricular (LV) blood ejection is a combined action of ventricular wall extrusion and the centrifugal force of an accelerated intra-ventricular vortex.
• The accelerated outflow during ejection likely induces spiral flow in the aorta, potentially influenced by the Valsalva sinus geometry.
• These findings provide novel insights into the complex hemodynamics governing cardiac ejection.