Continuous assessment of left ventricular shape in man

Area of Science:

• Cardiology
• Biomedical Engineering
• Medical Imaging

Background:

• Left ventricular function is crucial for cardiac health.
• Quantifying left ventricular shape dynamics provides insights into myocardial function.
• Previous methods may not fully capture shape changes during the cardiac cycle.

Purpose of the Study:

• To analyze left ventricular (LV) shape changes throughout the cardiac cycle using a novel shape index.
• To compare LV shape dynamics in healthy individuals versus patients with heart disease.
• To investigate the functional implications of altered LV shape during systole and diastole.

Main Methods:

• Frame-by-frame analysis of left ventriculograms in 10 normal subjects and 40 heart disease patients.
• Calculation of a left ventricular shape index (4π(cavity area)/perimeter²) to quantify circularity.
• Assessment of shape index changes during systole and early diastole, correlating with ejection fraction and regional wall motion abnormalities.

Main Results:

• Normal subjects showed a progressive reduction in shape index (less circular) during systole and a rapid increase during early diastole.
• Patients with low ejection fraction or regional hypokinesia (inferior/anterior) exhibited smaller systolic shape index reductions.
• Rapid diastolic shape index increase was linked to minor diameter expansion and could precede long axis changes.

Conclusions:

• Left ventricular shape undergoes significant, quantifiable changes during the cardiac cycle.
• Altered shape dynamics are associated with impaired systolic function and regional wall motion abnormalities in heart disease.
• Assumptions regarding LV cavity shape in volume estimation may need revision due to observed non-uniform wall motion during filling.