Heart | Critical aortic / pulmonary stenosis

The heart is made up of four important chambers (two ventricles and two atria, separated by a wall called a septum) and four important valves, as well as critical arteries and veins that all work together to pump blood from the heart to the lungs and to the rest of the body. Serious health risks may result from the abnormal development of any of these structures.

Essential Information

  • Aortic stenosis is caused by a narrowing or obstruction of the blood flow between the left side of the heart (the left ventricle) and the largest artery in the body, the aorta. In this case, the heart has to work much harder to pump blood out to the body, and as a result, the heart muscles may become thick or damaged, and the left ventricle may become enlarged.
  • Pulmonary stenosis is cause by a narrowing or obstruction of the blood flow between the right side of the heart (the right ventricle) and the pulmonary artery into the lungs. In this case, the right-side of the heart must work much harder and, again, may become tired or damaged.
  • Surgical intervention may be required to help unblock or stretch the narrowed passageway.
  • The timing of surgery depends on a number of factors, but may be impacted by the fetus’ position inside the womb. As a result, patients should be prepared to spend 2-3 days in hospital.

Overview

The heart is made up of four important chambers (two ventricles and two atria, separated by a wall called a septum) and four important valves, as well as critical arteries and veins that all work together to pump blood from the heart to the lungs and to the rest of the body. Serious health risks may result from the abnormal development of any of these structures.

Aortic stenosis is caused by a narrowing or obstruction of the blood flow between the left side of the heart (the left ventricle) and the largest artery in the body, the aorta. In this case, the heart has to work much harder to pump blood out to the body, and as a result, the heart muscles may become thick or damaged, and the left ventricle may become enlarged.

Pulmonary stenosis is cause by a narrowing or obstruction of the blood flow between the right side of the heart (the right ventricle) and the pulmonary artery into the lungs. In this case, the right-side of the heart must work much harder and, again, may become tired or damaged.

If left untreated, critical aortic or pulmonary stenosis will impact the health and function of the unborn baby’s heart and may progress to hypoplastic heart syndrome, a severe condition that can significantly impact the survival of the fetus and well-being outside of the womb.

The diagnosis of aortic or pulmonary stenosis will most often be made by ultrasound, and confirmed by a targeted assessment of the fetal heart structure and function, called an echocardiogram.

 

Treatment

The treatment of critical aortic or pulmonary stenosis inside the womb is a fetal balloon valvuloplasty. During this procedure, the fetus’ heart is accessed through the mother’s abdomen, and a small catheter containing a balloon is advanced, under ultrasound-guidance, through the narrowed passageway and inflated, relieving the obstruction and allowing blood to flow more easily and under less pressure. The balloon is then deflated and removed.

The fetus will still require monitoring and possible intervention after birth, but this procedure allows the heart to grow more normally while still inside the womb, and the newborn’s work-up and treatment can be organized in a less urgent fashion as a result.

 

Referral Information (for physicians)

Procedures are typically performed as soon as the diagnosis is confirmed to allow for maximal in-utero growth. Patients will be initially seen at Mount Sinai Hospital, then sent to get an echocardiography at The Hospital for Sick Children (SickKids). Patients should prepare for 2-3 days admission as surgical feasibility is highly dependent on fetal position. Postoperatively, out-of-province patients will be referred back to their local centre for further antenatal care and delivery. Local patients will have ongoing follow-up at Mount Sinai Hospital and SickKids.