Description

The mitral valve can be easily and accurately interrogated from the apical 4-chamber view. The pulse wave Doppler gate is placed within the valve annulus and the envelope is traced to measure the area under the curve (velocity time index; VTI). This provides a quantitative assessment of effective left ventricle preload (i.e. pulmonary venous return +/- net shunt across foramen ovale). In the setting of increased PVR and SVR MV regurgitation can also be seen as illustrated in this loop. In addition, Reduced pulmonary venous return is the hallmark of significant pulmonary hypertension. Using color flow Doppler the upper pulmonary veins can be visualized from the apical 4-chamber or the high parasternal view (See PDA module). The pulse wave Doppler gate is then placed within a vein as it enters the left atrium, parallel to the direction of flow. An average peak velocity of < 0.6 m/s during the first 24 hours of life is considered abnormally low. Owing to the complex anatomy and variation in flow, it is not possible to accurately quantify the blood return to the left heart. Nevertheless, by minimizing operator dependent variables serial evaluations can often provide meaningful insights in disease monitoring