Fetal and transitional circulation

Fetal and transitional circulation Fetal circulation is different from adult circulation. The changes occurring soon after birth constitutes transitional circulation. Respiratory gas exchange in the fetus occurs in the placenta rather than the lungs. Fetal cardiovascular system is designed so that the most saturated blood reaches the heart and the brain. Fetal circulation can be called a shunt dependent circulation because there are intracardiac and extracardiac shunts [1]. Cardiac output in the fetus is called combined ventricular output (CVO). Despite the low oxygen partial pressures in fetal blood, presence of fetal hemoglobin and high combined ventricular output helps in the oxygen delivery to the tissues. Fetal blood returns to the placenta by the umbilical arteries and returns to the fetus by the umbilical vein. More than half of this bypasses the hepatic circulation through the ductus venosus and reaches the inferior vena cava. Streaming of blood from the ductus venosus with saturation of 80-90% is separate from the desaturated blood returning from the lower part of the body. Eustachian valve at the junction of the inferior vena cava and right atrium directs this saturated blood to the foramen ovale and into the left atrium. Left atrial oxygen saturation is about 65% in the fetus. This saturated blood passes into the left ventricle and is ejected into the aorta. Major part of this blood reaches the cerebral and coronary circulation. Desaturated blood from the superior...
Source: Cardiophile MD - Category: Cardiology Authors: Tags: Cardiology Source Type: blogs