What is Ventricular Recruitment in Borderline CAVSD?

When a baby with Complete Atrioventricular Septal Defect (CAVSD) is diagnosed with a “borderline” or unbalanced heart, it means one of the heart’s lower pumping chambers (ventricles) is significantly smaller than the other—this can be either the right or the left ventricle, though the left is more commonly affected. Ventricular recruitment is a specialized, multi-step surgical strategy designed to “train” or encourage that smaller ventricle to grow ^[1][2]. Instead of immediately attempting a full repair, surgeons perform initial procedures to increase the amount of blood flowing into the small ventricle. This extra workload acts like physical therapy for the heart muscle, stretching it and stimulating it to grow larger and stronger over time ^[3][4]. If the ventricle grows enough, surgeons can eventually perform a full two-ventricle (biventricular) repair ^[5].

How Doctors Evaluate a “Borderline” Heart

In a typical, “balanced” CAVSD, the large hole in the center of the heart allows the single, common valve to deliver blood evenly to both the right and left ventricles. In an unbalanced (borderline) case, the valve sits off-center, directing most of the blood into one ventricle and leaving the other under-filled and smaller.

To decide if the smaller ventricle can be recruited, cardiologists rely on highly specific echocardiogram (ultrasound) measurements ^[6]. You may hear your team mention the Atrioventricular Valve Index (AVVI) or the modified Atrioventricular Valve Index (mAVVI). These indices measure exactly how much of the common valve opens into the smaller ventricle compared to the total valve area ^[7][8]. Along with measuring the total volume of the ventricle, these numbers help your surgical team predict whether a two-ventricle repair is possible or if a different pathway is safer ^[9].

How Ventricular Recruitment Works

If the surgical team decides to pursue ventricular recruitment, they will use one or more initial procedures to safely increase the pressure and volume of blood inside the smaller ventricle. Two common techniques include:

• Pulmonary Artery (PA) Banding: Surgeons place a small, adjustable band around the pulmonary artery (the blood vessel leading to the lungs). This protects the delicate lungs from receiving too much blood at too high a pressure ^[10]. Simultaneously, it increases the pressure inside the ventricle pumping to the lungs, forcing the heart to work harder ^[11]. This extra workload induces hypertrophy, meaning the heart muscle cells grow larger and thicker ^[4]. While the word “hypertrophy” can sound scary in other medical contexts, here it is healthy, intentional, and exactly the kind of growth the surgeon wants for your baby.
• ASD Restriction: The surgeon may partially close or narrow the Atrial Septal Defect (ASD)—the hole between the heart’s upper chambers. This forces more blood directly down into the small, borderline ventricle rather than letting it bypass to the larger side ^[12].

The Waiting and Growth Phase

Together, these procedures force the small ventricle to fill with more blood and pump harder, stimulating growth over several months ^[3][13]. During this “interstage” waiting period, your baby will typically be able to go home, though they will be monitored very closely. You will have frequent clinic visits for echocardiograms to measure the ventricle’s growth ^[14]. At home, parents are taught to watch for warning signs that the heart is struggling with the new workload, such as poor feeding, rapid breathing, or unusual color changes, which should be reported to the care team immediately.

The End Goal and the “Plan B”

The ultimate goal of ventricular recruitment is to grow the borderline ventricle enough so that it can handle a normal workload, allowing the baby to undergo a full biventricular (two-pump) repair later on ^[1][5]. Achieving a two-ventricle circulation is generally preferred, but this multi-stage approach is complex and patients often require frequent monitoring and sometimes additional valve surgeries down the road ^[15][16].

It is important to know that ventricular recruitment does not always work. Even with PA banding and other interventions, the smaller ventricle sometimes does not grow enough to support the body’s circulation safely. If this happens, the surgical team will pivot to a “Plan B.” This typically means moving to a single-ventricle pathway (often called the Fontan pathway) ^[17]. In this scenario, the large, healthy ventricle does all the pumping for the body, while blood returns passively to the lungs. While a single-ventricle pathway is fundamentally different, it is a well-established and life-saving alternative for children whose borderline ventricle cannot be successfully recruited ^[18][19].