Noninvasive measurement of cardiac function during exercise, using resaturation curves

Area of Science:

• Cardiology
• Medical Diagnostics

Background:

• Cardiac valvular disease affects heart function.
• Noninvasive methods are needed for cardiac assessment.

Purpose of the Study:

• To evaluate the resaturation curve as a noninvasive indicator of cardiac performance.
• To assess cardiac function in patients with valvular heart disease.

Main Methods:

• Used the resaturation curve, an indicator-dilution test with an ear oximeter.
• Measured time constant of resaturation (tau) and left heart clearance fraction during exercise.
• Compared 108 patients with cardiac valvular disease to normal subjects.

Main Results:

• Patients with valvular disease had significantly reduced clearance fraction and longer tau compared to normal subjects.
• Aortic valve replacement improved clearance fraction and tau.
• Medically treated patients showed deterioration in tau and clearance fraction over time.

Conclusions:

• The resaturation curve is an objective, repeatable measure of cardiac impairment.
• This noninvasive test aids in follow-up of heart disease patients.
• Resaturation curve parameters correlate with hemodynamic data.