What are the differences between a fetus heart and an adult heart?

Answer 1

The fetal and adult cardiovascular systems exhibit significant differences, reflecting different sources of respiratory and nutritional support. Most strikingly, the embryonic lungs are collapsed and nonfunctional, and the digestive tract has nothing to digest. The nutritional and respiratory needs of the fetus are provided by the diffusion across the placenta. Blood flow to the placenta is provided by a pair of umbilical arteries which arise from the internal iliac arteries and enter the umbilical cord. Blood returns from the placenta in the single umbilical vein, bringing oxygen and nutrients to the developing fetus. The umbilical vein drains into the ductus venosus, a vascular connection to an intricate network of veins within the developing liver. The ductus venosus collects blood from the veins of the liver and from the umbilical vein, and empties into the inferior cava. When the placental connection is broken at birth, blood flow ceases along the umbilical vessels, and they soon degenerate. However, remnants of these vessels persist throughout life as fibrous cords. Throughout embryonic and fetal life, the lungs are collapsed; yet after delivery, the newborn infant must be able to extract oxygen from inspired air rather than across the placenta. Although the interatrial and interventricular septa develop early in fetal life, the interatrial partition remains functionally incomplete until birth. The foramen ovale, or interatrial opeing, is associated with a long flap that acts as a valve. Blood can flow freely from the right atrium to the left atrium, but any backflow will close the valve and isolate the two chambers from one another. Thus, blood entering the heart at the right atrium can bypass the pulmonary circuit. A second short-circuit exists between the pulmonary and aortic trunks. This connection, the ductus arteriosus, consists of a short, muscular vessel. With the lungs collapses, the capillaries are compressed and little blood flows through the lungs. During diastole, blood enteres the right atrium and flows into the right ventricle, but it also passes into the left atrium through the foramen ovale. Avout 25 percent of the blood arriving at the risght atrium bypasses the pulmonary circuit in thie way. In addition, more than 90 prcent of the blood leaving the right ventricle passes through the ducus arteriosus and enters the systemic circuit rather than continuing to the lungs. After birth, when the infant takes the first breath, the lungs expand, and so do the pulmonary vessels. The resistance in the pulmonary circuit declines suddenly, and blood rushes into the pulmonary vessels. Within a few seconds, rising oxygen levels stimulate the constriction of the ductus arteriosus, isolating the pulmonary and aortic trunks from one another. As pressures rise in the left atrium, the valvular flap closes the floramen ovale. In adults, the interatrial septum bears the fossa ovalis, a shalow depression that marks the side of the foramen ovale. The remnants of the ductus arteriousus, persists throughout life as the ligamentum arteriosum, a fibrous cord. The fetal and adult cardiovascular systems exhibit significant differences, reflecting different sources of respiratory and nutritional support. Most strikingly, the embryonic lungs are collapsed and nonfunctional, and the digestive tract has nothing to digest. The nutritional and respiratory needs of the fetus are provided by the diffusion across the placenta. Blood flow to the placenta is provided by a pair of umbilical arteries which arise from the internal iliac arteries and enter the umbilical cord. Blood returns from the placenta in the single umbilical vein, bringing oxygen and nutrients to the developing fetus. The umbilical vein drains into the ductus venosus, a vascular connection to an intricate network of veins within the developing liver. The ductus venosus collects blood from the veins of the liver and from the umbilical vein, and empties into the inferior cava. When the placental connection is broken at birth, blood flow ceases along the umbilical vessels, and they soon degenerate. However, remnants of these vessels persist throughout life as fibrous cords. Throughout embryonic and fetal life, the lungs are collapsed; yet after delivery, the newborn infant must be able to extract oxygen from inspired air rather than across the placenta. Although the interatrial and interventricular septa develop early in fetal life, the interatrial partition remains functionally incomplete until birth. The foramen ovale, or interatrial opeing, is associated with a long flap that acts as a valve. Blood can flow freely from the right atrium to the left atrium, but any backflow will close the valve and isolate the two chambers from one another. Thus, blood entering the heart at the right atrium can bypass the pulmonary circuit. A second short-circuit exists between the pulmonary and aortic trunks. This connection, the ductus arteriosus, consists of a short, muscular vessel. With the lungs collapses, the capillaries are compressed and little blood flows through the lungs. During diastole, blood enteres the right atrium and flows into the right ventricle, but it also passes into the left atrium through the foramen ovale. Avout 25 percent of the blood arriving at the risght atrium bypasses the pulmonary circuit in thie way. In addition, more than 90 prcent of the blood leaving the right ventricle passes through the ducus arteriosus and enters the systemic circuit rather than continuing to the lungs. After birth, when the infant takes the first breath, the lungs expand, and so do the pulmonary vessels. The resistance in the pulmonary circuit declines suddenly, and blood rushes into the pulmonary vessels. Within a few seconds, rising oxygen levels stimulate the constriction of the ductus arteriosus, isolating the pulmonary and aortic trunks from one another. As pressures rise in the left atrium, the valvular flap closes the floramen ovale. In adults, the interatrial septum bears the fossa ovalis, a shalow depression that marks the side of the foramen ovale. The remnants of the ductus arteriousus, persists throughout life as the ligamentum arteriosum, a fibrous cord.

Answer 2

The heart starts out as a tube around 5 weeks and then forms 4 chambers. By 24 weeks, the fetus's heart is fully formed. However, the oxygen is supplied through the placenta from the mother's lungs. So, a fetus's heart has an extra pathway connecting the aorta (normally carrying oxygen-rich blood away from the heart) and the pulmonary artery (normally carrying oxygen-depleted blood to the lungs) called a Patent Ductus Arteriosis (PDA).

The PDA usually closes within the first 10 days of life. If it doesn't close on it's own, there's some medications that closes it. If that doesn't work, surgery is required. Some congenital heart defects (like hypoplastic left heart syndrome) become life threatening after the PDA closes.

Answer 3

The fetus does not use its lungs to bring oxygen to the blood.

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The umbilical vein brings oxygenated and nutrient rich blood from the placenta into the right atrium. From there, it travels through the Foramen Ovale, which is a one way valve between the right atrium and the left atrium. This essentially short circuits the lungs. Return blood back to the placenta is via the umbilical artery.

At birth, when the infant starts breathing, the pressure differential between the left atrium and the right atrium increases, causing the Foramen Ovale to close, removing the short circuit. Now, blood has the full path from right atrium, to right ventricle, to lungs, to left atrium, to left ventricle, to the body, and repeating. The Foramen Ovale typically stays unsealed for about 9 months, although it still closes when the left atrium beats. After about 9 months, it seals permanently due to incorporation into the heart wall and stays that way.

The umbilical vein and artery atrophy normally, because there is no longer any blood flow through them.

In about 40% of the population, this sealing is incomplete, giving what is called a Patent (Open) Foramen Ovale, or PFO. Most people do OK with that. About 40% of the 40% have symptoms, but they often go undiagnosed because it is difficult to confirm and because the symptoms can be caused by other things.

Symptoms are vague, and there is no official consensus, but some doctors believe that a PFO can cause migraine, atrial fibrillation/flutter, and/or stroke. The problem is twofold. First, you have unoxygeneated blood going into the left atrium. Second, you lose the natural filtering effect of the lungs in response to normal clots that develop in everyone, but should be trapped and dissolved in the lungs - those clots can go anywhere - including the brain and the heart.

There was a study performed in the UK that attempted to show the correlation between PFO and migraine. Supposedly, the study was abandoned because too many people were being helped by PFO closure that they decided to just close everyone's PFO. On the US side, there was objection because the results were anecdotal and the study was not a double blind study. I see both sides of the argument, and really have no further opinion about the adequacy of available therapies.

Primary therapy of a PFO is anti-coagulants, or what we call blood thinners. If there is evidence that this does not help, it is possible to close the PFO surgically, often intra-venously. Sometimes, you have to "argue" with the insurance company - it helps to have a doctor that is willing to go to bat for you. This happened to me, and I got my PFO closed, in the US, and I am quite happy with the results.

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Answer 4

What are the major differences between the fetal and the adult human heart?