Many people have been told that they have a “hole” in their heart.
What does that mean – exactly? Wouldn’t a “hole” allow the blood to run out and they would die? Where is the “hole”?
The heart has four chambers. On the right side is a small upper chamber (right atrium) which receives blood from the body and empties through a one-way valve into the larger lower chamber (right ventricle). This chamber empties under low pressure through a one-way valve into the pulmonary artery and into the lungs to pick up oxygen. On the left side is a small upper chamber (left atrium) which receives blood from the lungs and empties through a one-way valve into the much larger lower chamber (left ventricle). This very large chamber empties under high pressure through a one-way valve into the aorta and into the rest of the body.
While still in the mother’s womb, the fetal heart has a by-pass “hole” through a flap valve between the two upper chambers (foramen ovale in the atrial septum). This “hole” allows blood to pass directly from the right side into the left side of the heart without going to the non-functioning fetal lungs. A second “hole” for the same purpose of by-pass is a small channel (ductus arteriosus) between the pulmonary artery and the aorta, kept open by hormones from the mother’s placenta.
At the moment the child takes it first breath, the pressure drops in the right upper chamber. The higher pressure in the left upper chamber closes the flap valve, closing the first “hole” (foramen ovale). When the umbilical cord is clamped, the hormones from the placenta are cut off. With rising levels of oxygen from breathing and hormones from the infant lung, the second “hole” (ductus) closes. As the lungs expand, the blood flows in from the right side of the heart.
In 25% of people, the foramen ovale does not close. This can be one way for blood clots from the legs to cross from the right side to the left side of the heart and potentially into the heart or brain circulation. Rarely does the ductus arteriosus remain patent. But when it does, the infant shunts blood from the high pressure left side into the low pressure right side, overloading the right side of the heart, causing difficult breathing and eventually heart failure.
A third “hole” in the heart is a malformation and can occur between the two lower chambers (ventricular septal defect). This defect causes the high pressure left ventricle to shunt blood into the low pressure right ventricle, causing overload of the lungs and increasing the pressure in the right heart causing heart failure and difficult breathing in the infant and in the adult who still has it.
Most heart “holes” close spontaneously. Most remaining “holes” cause little or no problem. But a few require some type of intervention to repair and close them before permanent damage is done to the lungs and the heart. Fortunately, the majority of people do not have a “hole” in their heart and they make the amazing switch of circulation at birth when – by design – all of their “holes” close.
