Analysis and prediction of left ventricular performance under load changes during cardiac catheterization

Area of Science:

• Cardiovascular Physiology
• Computational Biology
• Medical Imaging

Background:

• Assessing left ventricular (LV) global function under varying loading conditions is critical in cardiology.
• Computer models offer a potential tool to analyze complex cardiac mechanics non-invasively.
• Previous models have limitations in accurately predicting LV performance across different physiological states.

Purpose of the Study:

• To evaluate the applicability of a computer model that links transmural mechanical distribution in the LV to its global function.
• To assess the model's accuracy in predicting LV performance under baseline and altered loading conditions (volume expansion and vasodilation).
• To determine the model's sensitivity to changes in myocardial contractility, particularly during acute ischemia.

Main Methods:

• A computer model was applied to 20 patients undergoing cardiac catheterization with normal to near-normal LV function.
• Input data included left ventriculography, LV pressures, aortic pressures, and heart rate.
• Model parameters (myocardial contractility, arterial capacitance) were estimated by matching predicted to measured end-systolic (ES) volume and pressure under baseline conditions.

Main Results:

• The model demonstrated excellent correlation (R2 > 0.994) between predicted and measured LV ES volumes and peak-systolic pressures (PSP) under altered loading conditions.
• Predictions for ES volumes were lower than measured values in four patients who developed ischemic symptoms, indicating model sensitivity to contractility changes.
• The model successfully predicted global LV performance metrics, including stroke work, peak developed wall stress, velocity of fiber shortening, and myocardial oxygen consumption.

Conclusions:

• The computer model accurately predicts global left ventricular performance across different loading conditions.
• The model is sensitive to changes in myocardial contractility, as evidenced by its performance during induced ischemia.
• This validated model holds promise for non-invasive assessment of cardiac mechanics and function in clinical settings.