How long does it take blood to reach the left ventricle from the right ventricle?
That will be practically the pulmonary circulation time, the time taken for the blood ejected from right ventricle into pulmonary artery to travel through the lungs. Blood returns from the lungs through pulmonary veins to left atrium and then into the left ventricle. Normally this takes about 6 seconds. It may be prolonged in right ventricular failure.
The transit from right ventricle to left ventricle will be almost instantaneous if there is a ventricular septal defect with pulmonary hypertension and right to left shunt. The transit time will be shortened if there is a pulmonary AV fistula. This can be seen by injecting agitated saline containing microbubbles of air into a vein. Normally the bubbles are destroyed in the lungs and do not reach the left side of the heart. If there is a pulmonary AV fistula, they reach the left atrium and ventricle two or three cycles after reaching the right atrium. If there is an atrial or ventricular septal defect with right to left shunt, then they reach the left side almost instantaneously after reaching the right atrium.