Assessment of left ventricular diastolic function
A classic clinical application of Doppler ultrasonography is the analysis of the blood flow velocity spectrum across the mitral orifice during early diastole (transmitral flow). The main parameters are:
- Peak E — characterizes early diastolic ventricular filling.
- Peak A — reflects late filling driven by atrial systole.
Analysis of the E/A ratio, flow deceleration time, and tissue Doppler imaging (the e' parameter) allows for the algorithmic determination of the severity of diastolic dysfunction. These echocardiographic findings reflect mean left atrial pressure and are crucial for diagnosing heart failure with preserved ejection fraction.
Diagnosis of valvular regurgitation
Doppler examination serves as the primary tool for detecting valve regurgitation. This is particularly significant because direct morphological leaflet defects are not always visible, and indirect signs are limited to chamber dilation. The method offers high sensitivity due to two technologies:
- Color Doppler flow mapping — directly visualizes the direction of blood flow and the regurgitant jet.
- Quantitative assessment (using pulse-wave Doppler) — allows calculation of the regurgitant volume and regurgitant orifice area.
For example, the diagnosis of aortic regurgitation is definitively confirmed by recording reverse blood flow from the aorta into the left ventricular cavity during diastole. In mitral regurgitation, hemodynamics change compensatorily: to maintain an adequate stroke volume, overall LV contractility and the ejection fraction (EF) increase.
Quantitative assessment of stenotic lesions
Doppler echocardiography provides the ability to precisely determine the degree of valve narrowing, such as in mitral or aortic stenosis. Three parameters are used in diagnostics:
- Valve orifice area.
- Transvalvular pressure gradient (pressure difference between chambers before and after the narrowing).
- Pulmonary artery pressure.
In addition, M-mode echocardiography visualizes characteristic leaflet motion (e.g., anterior AM and posterior PM mitral valve leaflets). Diagnostic criteria for severe aortic stenosis include: a mean pressure gradient greater than 40 mmHg, a valve area less than 1 cm², and a peak flow velocity greater than 4.0 m/s. These data are critical during preoperative evaluation before noncardiac interventions.
Evaluation of the left ventricle in endocarditis and MVP
In infective endocarditis, the echocardiographic protocol necessarily includes assessing left ventricular size and function, right ventricular function, pulmonary artery systolic pressure, and the presence of pericardial effusion. A direct pathognomonic sign is the detection of vegetations on the valve leaflets, while indirect signs include destruction of the apparatus (rupture of chordae tendineae, leaflet perforation, or the formation of a flail leaflet).
A frequent cause of severe non-ischemic regurgitation is mitral valve prolapse syndrome (MVP). On echocardiography as the primary diagnostic method (in the parasternal long-axis view), MVP is defined as systolic bulging (prolapse) of a leaflet by more than 2 mm beyond the plane of the annulus fibrosus into the atrial cavity.
Hemodynamic impact on the left ventricle
LV pathology is inextricably linked with changes in other heart chambers. Doppler echocardiography allows non-invasive estimation of pulmonary artery systolic pressure (normal 15–30 mmHg). Signs of right heart overload secondarily affecting the LV include: flattening of the interventricular septum, a left ventricular eccentricity index greater than 1.1, and an early diastolic pulmonary regurgitation velocity greater than 2.2 m/s.
Echocardiography also evaluates the hemodynamic patterns of acute and chronic mitral regurgitation:
- Acute mitral regurgitation: acute volume overload of a noncompliant (noncompliant) left atrium leads to a marked pressure elevation and acute pulmonary edema.
- Chronic mitral regurgitation: the left ventricle and atrium dilate, acting as a reservoir for the regurgitant volume, which prevents rapid pressure rises in the pulmonary vessels until decompensation occurs.
Transmitral flow is easy to remember by its initial letters: E (from Early) — early diastolic filling; A (from Atrial) — late filling during atrial systole.
Class and exam questions
How does echocardiography confirm aortic valve regurgitation?
A key sign is the recording of reverse blood flow (regurgitation) from the aorta into the left ventricular cavity during diastole.
What echocardiographic criteria indicate severe aortic stenosis?
Severe stenosis is indicated by a mean pressure gradient greater than 40 mmHg, a valve orifice area less than 1 cm², and a peak transvalvular flow velocity exceeding 4.0 m/s.
What is mitral valve prolapse on echocardiography?
This is a pathological systolic bulging of the mitral valve leaflet into the left atrial cavity by more than 2 mm beyond the plane of the fibrous annulus.
What echocardiographic signs indicate right heart overload and pulmonary hypertension?
This is indicated by flattening of the interventricular septum, an LV eccentricity index greater than 1.1, pulmonary artery dilation greater than 25 mm, and a right atrial area greater than 18 cm².
What else to study on this topic
- 17-segment model for assessing left ventricular myocardium in short-axis views.
- CT angiography and coronary artery evaluation with prospective ECG gating.
- Radiographic presentation of the lungs and cardiac silhouette in acute and chronic mitral regurgitation.
- Assessment of resistive indices (Resistive Index) using peripheral and renal vessel Doppler sonography.
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