A review of cardiac catheterization

Not very long ago children with congenital heart disease had few treatment options. Thankfully, that is no longer the case.

Duke pediatric cardiologist Gregory A. Fleming, MD, MSCI, explains exciting research in interventional cardiology and how that translates to treatments for children.

-- Dennis Clements MD, PhD, MPH

Gregory A. Fleming, MD, MSCIA diagnostic cardiac catheterization is a procedure in which small, flexible catheters are inserted through veins or arteries into the heart to measure oxygen levels and pressures in chambers of the heart as well as inject a special dye into the heart to visualize the structures of the heart under x-ray (fluoroscopy).

The purpose of a diagnostic catheterization is to obtain information to help guide further treatment.

What Is Interventional Cardiology?

Interventional cardiology refers to interventions performed by a cardiologist during a cardiac catheterization procedure to fix or stabilize certain problems within the heart or within blood vessels of the heart.  

Interventions are commonly performed on adults with blockage of the coronary arteries (the blood vessels that supply the heart muscle with oxygen) to prevent heart attacks. These interventions usually consist of dilating the coronary arteries with special balloon catheters and sometimes placing a metal stent into the narrowed portion of the coronary artery.

Interventions in children are usually different than those performed in adults. In children, many different types of interventions are performed to fix or stabilize malformations or birth defects of the heart (Congenital Heart Defects) that can occur during development of the heart.

Numerous devices have been specially engineered to close abnormal blood vessel connections and abnormal holes between chambers of the heart. These devices are released into the heart through the catheters that are inserted into the veins and arteries.

Some common interventions in children that have been performed for many years are:

• Creation of a hole between the two upper chambers of the heart (balloon atrial septostomy) in some “blue babies” to allow them to survive until a corrective surgery can be performed
• Closure (embolization) of a patent ductus arteriosus (PDA), an abnormal connection between the artery going to the body (aorta) and the artery going to the lungs (pulmonary artery),  or other abnormal blood vessels with a small metal plug or a metal coil
• Closure of an atrial septal defect (ASD), an abnormal opening between the two upper chambers of the heart, with a device inserted through a special catheter
• Opening up narrowed or abnormal heart valves (valvuloplasty) with special balloon catheters in order to relieve obstruction
• Opening up narrowed blood vessels (angioplasty) with special balloon catheters with or without metal stents

Newer Applications of Interventional Cardiology in Children

Exciting research is ongoing in the field of interventional pediatric cardiology. Some of this research has resulted more recently in the following:

• New types of interventions that can be performed in the catheterization lab and therefore prevent the need for open heart surgery
• Hybrid procedures: Interventions that can be performed by interventional cardiologists working with pediatric heart surgeons to make the procedure better and safer
• Fetal interventions: Interventions performed before delivery of fetuses that are diagnosed during pregnancy with life threatening heart disease. These procedures can help the heart develop with an improved chance of survival after delivery
• Perfecting the types of devices currently being used to close holes and abnormal vessels

Some examples of newer applications of interventional cardiology in children are:

• Replacing heart valves (pulmonary valve replacement) using valves that are sewn into metal stents and inserted in the heart using special balloon catheters
• Using devices to close holes between the lower pumping chambers of the heart (ventricular septal defects) that are delivered using special catheters
• Hybrid procedures:
• Hybrid Norwood procedure: newer procedure used for babies born with underdevelopment of the left side of the heart (hypoplastic left heart syndrome)
• Closing ventricular septal defects (VSD) with a device inserted by a cardiologist through a small puncture of the heart made by a cardiac surgeon without the need for a heart lung bypass machine
• Fetal interventions:
• Opening up narrowed valves (valvuloplasty) during pregnancy in order to allow improved development and function of the other chambers of the heart before delivery
• Creating holes in the heart (septostomy) to allow relief of elevated pressures in the heart that would cause significant problems after delivery

Those are a few of the many new opportunities that exist for children with heart disease. It is an exciting time for research in this area, and we expect that more advances will come to fruition in the coming years.

--  Gregory A Fleming, MD, MSCI, is a pediatric cardiologist in the Duke Department of Pediatrics. 

-- Dennis Clements, MD, PhD, is the chief of primary care pediatrics at Duke Children's Hospital.