The technology required to perform all these analyses is available on most commercially available systems and the time required to obtain a detailed assessment of diastolic function is minimal.
Myocardial Performance Index
The myocardial performance index, first introduced by Tei and colleagues, integrates myocardial systolic and diastolic function. It is defined as:
This easily derived index has been applied to both right and left ventricles.
Atrioventricular Valve Function
Functional mitral and tricuspid regurgitation frequently accompany left ventricular systolic dysfunction and may contribute significantly to patient symptomatology. Echocardiography has proved instrumental in delineating the pathophysiology of functional mitral regurgitation. A number of animal and clinical studies using both 2-D and 3-D techniques have demonstrated a path gnomonic pattern of leaflet closure termed apical tethering. One of the key causes of this disturbance of leaflet coaptation is increased tethering forces on the leaflets and chords created by geometric remodeling of the left ventricle and attendant papillary muscle displacement. By exerting traction at the site of leaflet insertion, annular dilation also contributes to pathologic leaflet tethering.
The other important causative factor is a reduced valvular closing force due to impaired left ventricular contraction. Functional tricuspid regurgitation appears to have a similar pathophysiology. It may occur on the basis of either primary right ventricular systolic dysfunction or due to the right ventricular remodeling that may develop in the setting of primary left-sided failure and secondary pulmonary hypertension.
Over the last decade, the ability of echocardiography to define cardiac hemodynamics has been greatly expanded. One of the earliest applications of echocardiography was the determination of cardiac output based on calculating forward flow across the cardiac valves.This calculation is based on the fact that stroke volume equals the product of cross-sectional area and velocity time interval (the integrated area under the pulsed Doppler spectral curve) for flow per beat through that area.
- A full discussion of these techniques is beyond the scope of this article and the reader is referred to an excellent review on the subject by Nagueh, et al., in the American College of Cardiology Current Journal Review (Jan/Feb 2002).