“Efficacy and durability of embolization of systemic-to-pulmonary collateral vessels in superior cavo-pulmonary connection patients prior to Fontan completion”

Doctor's Name: 
Andrew C. Glatz, M.D.
The Children’s Hospital of Philadelphia

Congenital heart disease occurs in many forms, from minor defects to very complicated lesions.  One fundamental method of classifying congenital heart disease is based on the number of ventricles—that is pumping chambers—that the heart has.  A normal heart has two pumping chambers, one to the lungs and the other to the body.  Some children are born with such severe defects that only one ventricle is functional.  Those children require a multi-step procedure that ultimately connects the blood returning from their body directly into the lungs and makes the single ventricle the chamber that pumps blood to the body.

Clearly, this circulatory pattern is not what nature intended.  And it has many consequences.  One of those consequences arises because flow to the lungs is abnormal, and becomes a passive process rather than an active one in a typical heart with a pumping chamber to the lungs.  For reasons that are unclear, these patients are known to develop an abnormally large number of bypass—a.k.a. collateral—vessels, which allow for the flow of blood from the aorta or its branches to go directly to the lungs.  Doctors are uncertain of the consequence and effect these collateral vessels have on a patient with single-ventricle heart disease.  Thus, clinical practice varies considerably, though this practice is not based on well-corroborated science.  Some physicians close these collateral vessels via a cardiac catheterization prior to second and third stage surgeries which nearly all single-ventricle patients undergo; other physicians do nothing to these vessels.  No scientific studies have adequately determined which approach is best.  Our research group has recently developed a new method to measure collateral flow by cardiac MRI.  This provides us with a unique opportunity to better study collateral flow.

Our study proposes to help inform the understanding and management of these collateral vessels.  We propose to perform a study on patients with single-ventricle heart disease who are awaiting the third/final stage of surgery, and who have a known amount of collateral vessel flow based on studies that were performed to care for them.  We propose to take the patients and to close those vessels prior to their third surgery.  We will then perform a cardiac MRI—a test with no known harm—just after the procedure to close the vessels to determine the success of the closure attempt.  We will then perform another cardiac MRI on the day of their third/final surgery to determine how many collateral vessels stayed closed and if any new ones grew.  We will then compare these patients with a “control” group, who have similar single-ventricle heart disease undergoing the same operation, but who did not have their collateral vessels closed.  We hope to determine if there are any significant differences between these groups, to help learn the importance of these collateral vessels in single-ventricle heart disease.  We also hope to determine the optimal manner in which these collateral vessels should be treated, if at all.

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