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TELECONFRENCES
2004
The Changing Left Ventricle

2003
Aortic Valve Disease: New Dimensions in Evaluation and Management

2002
Heart Failure: Echo's Role in and Emerging Health Crisis

2001
Chest Pain in Children & Adults: The Role of Echo

2000
Mitral Regurgitation: New Concept

1998
The Falling Left Ventricle: Diastolic & Systolic Function

1997
Changing the Outcome of Coronary Artery Disease
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VIDEO ARCHIVES

Chest Pain in Children and Adults

Mitral Regurgitation: New Concepts

Diastolic and Systolic Function

Changing the Outcome of CAD

BROADCAST SUPPLEMENTS
2000 MV
2001 Chest Pain
2002 Heart Failure



Color Flow Imaging of Valvular Regurgitation
Mitral Regurgitation
Fig.4.22

Normal diastolic flow through the mitral valve is very low velocity and rarely exceeds 1.5 m/s. Aliasing is, therefore, seldom seen during diastole when using a 2.5 MHz transducer. Figure 4.22 demonstrates normal diastolic flow emerging from a superior pulmonary vein and then entering the left ventricle through the open mitral valve leaflets.

 

Fig.4.23

During systole, the left atrium is usually free from color. In
Figure 4.23
mild mitral regurgitation is seen to be directed along the posterior mitral leaflet toward the posterior left atrial wall. Aliasing is present due to the increased velocity and turbulence through the closed valve orifice, and appears as a bright mosaic of colors.

Mitral regurgitation can usually be detected using any view, even the parasternal long axis when the jet is perpendicular to the ultrasound beam. This is possible because most abnormal flows within the heart are turbulent. Many eddy currents exist in literally hundreds of directions simultaneously. Thus, while the main vector of the regurgitant jet may be generally perpendicular to the interrogating beam, some of the eddies within the main jet are oriented parallel to the beam. In most cases, these signals are sufficiently strong to be detected by the color flow imaging device. Thus, some spatial representation of flow will be seen by color flow methods.

Quantifying the severity of valvular regurgitation is based approximately on the size and configuration of the regurgitant jet. Very small jets, localized just to the proximal side of the regurgitant valve, usually signify trivial valvular insufficiency. Large jets that fill the receiving chamber usually indicate significant valvular insufficiency (Fig. 4.1).

Fig.4.24

Moderate mitral regurgitation is shown in Figure 4.24. Again, the hallmark is the systolic appearance of a posteriorly directed jet comprising aliased colors and turbulence. Regurgitant jets may go in any direction and have virtually any appearance. Figure 4.25 demonstrates mitral regurgitation seen from the subcostal view in a 5-year-old boy where the jet is more diffuse and occupies almost all of an enlarged left atrium. In this case, severe mitral regurgitation is present.

Fig.4.25

It is imperative to remember that many factors influence the size, configuration, and appearance of regurgitant lesions. Among them are the volume of the jet, pressure difference between the regurgitant and receiving chamber, size of the regurgitant orifice, configuration of the regurgitant orifice and the size of the receiving chamber. Other factors such as the timing of regurgitation, loading conditions, heart rate, and rhythm may also be of importance. As mentioned above, the orientation of the jet to the beam is also a factor. Considerable work remains in verifying the significance of these and other influences.

Fig.4.26

Mitral regurgitation may be found by color flow imaging in any clinical state associated with this lesion, and may result from prolapse, rheumatic, infectious or other etiologies. Continued use of color flow imaging has revealed the frequent association of mitral regurgitation (Fig. 4.26) in patients with diffuse cardiomyopathies of virtually any origin. In our laboratory, we have encountered mitral regurgitation in 100% of patients with this disorder when the left ventricle measures 6 cm or greater in diastole. In each case, the mitral regurgitation was quantified at 2+ or greater (out of a scale of 4). Of further interest is the fact that there is a surprisingly high prevalence of regurgitation of the other heart valves. In patients with dilated cardiomyopathy, there is 2+ or greater regurgitation of the tricuspid valve in 91%, the aortic valve in 23%, and the pulmonic valve in 58%. In these patients, forward flow is usually of very low velocity and results in dull hues of color.

Due to the considerable savings of time, we now use only the color flow approach in routine cases for detection of all valvular insufficiencies. This is not done, however, without attending to all the factors that may affect the reliability of our estimation of severity.

Operator skill is important. The use of too little gain will make regurgitant lesions appear unduly small, and can be a prime source of underestimation. Proper transducer angulation into the regurgitant lesion is also important. For small and eccentrically direct jets, extra time is required to be sure of proper identification. Hastily conducted studies limited only to traditional views may not reveal these types of abnormalities.

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