Atrioventricular Septal Defect or AV Canal (AVSD)

Atrioventricular Septal Defect or AV Canal (AVSD)

  • Overview
  • Appointments
  • Symptoms
  • Diagnosis
  • Treatments
  • Locations

    • What is Atrioventricular Septal Defect?

    Atrioventricular Septal Defect (AVSD), or AV canal, is a heart defect that involves the valves between the heart's upper and lower chambers and the walls between the chambers. Other terms used to describe this problem include endocardial cushion defect and AV canal defect. A similar but less serious form of atrioventricular septal defect is called primum atrial septal defect or incomplete or partial atrioventricular septal defect.

    The heart's upper chambers are called the atria and the lower chambers are called the ventricles. The wall between the upper chambers is called the atrial septum and the wall between the lower chambers is called the ventricular septum. In the normal heart, the valve between the right atrium and right ventricle is called the tricuspid valve and the valve between the left atrium and the left ventricle is called the mitral valve. In children with AVSD, the tricuspid and mitral valves do not develop normally which then affects the growth of the atrial and ventricular septum. 

    Most of the time, there is one "common" valve separating the hearts upper and lower chambers instead of two separate valves. In addition, there is a hole in the atrial septum called an atrial septal defect and a hole in the ventricular septum called a ventricular septal defect. In primum atrial septal defect, there are two separate valves between the upper and lower heart chambers but they are not entirely normal and there is an atrial septal defect.

    Appointment Information

    To make an appointment to discuss your congenital heart problems, call us at 877-720-3983.

    What are the symptoms of AVSD?

    Atrioventricular septal defect is a serious heart problem that usually causes heart-related symptoms. Unlike some heart defects, the problem does not resolve with time and most children must undergo heart surgery. The good news is that this surgery is usually very successful and most children do very well. There are some patients with primum atrial septal defect who do not require surgery because the valves have little or no leakage and the atrial septal defect is small. 

    The effects from AVSD are caused by the holes in the heart walls and leakage from the abnormal valve. The holes allow blood in the heart's left side (oxygenated or red blood that has returned from the lungs) to leak back to the heart's right side. This results in a large amount of blood that the right side of heart must pump again to the lungs. The heart has to work much harder than normal to pump enough blood out to the body because so much of it returns instead to the heart's right side. The workload is further increased by leakage of the heart valve. As a result of the extra workload, most babies with AVSD develop signs of congestive heart failure including: 

    • Rapid breathing
    • Feeding problems
    • Slow weight gain
    • Low energy
    • Cold, clammy sweating

    These symptoms usually appear between 4 and 8 weeks of age but can occur earlier in some infants.

    Another possible health effect of AVSD is pulmonary artery hypertension. This problem develops more slowly and is caused by the extra pulmonary blood flow. The pulmonary arteries that take blood from the heart's right side to the lungs are not well suited to the increased pressure caused by the extra blood flow. Over time, if the problem is not corrected, the pulmonary arteries become thick and stiff which makes the heart have to work even harder. This is a very serious problem with no effective treatment. For unknown reasons, children with Down syndrome are very prone to this problem so heart surgery is often done when the child is 4-6 months old.

    How is AVSD diagnosed?
    Clinical Findings

    Most newborns with AVSD do not have heart related symptoms, however, congestive heart failure usually develops during the first 1 to 2 months of life. Problems with slow growth and slow motor development are not uncommon. Some babies with AVSD look a little blue in the lips and/or under their fingernails, especially when they cry. This is called cyanosis and occurs when blood on the right side of heart flows to the left side of the heart (and out to the body) through one of the holes. 

         Physical Findings

    A heart murmur is often the first clue that a child has an AVSD. In many children, the murmur is heard right after birth but it may not be heard until the child is 6 to 8 weeks of age. If the child is in congestive heart failure, there will be poor weight gain, the heart rate and breathing rate will be higher than normal, and the liver will be enlarged. 

         Medical Tests

    The following tests will be ordered:  

    • Electrocardiogram
    • Chest x-ray
    • Oxygen saturation test

    An AVSD alters the placement of the conduction or electrical system of the heart that often shows up as an abnormality on the electrocardiogram. The oxygen level in the blood is usually normal but can be a little low. The chest x-ray often shows a bigger than normal heart and extra blood flow to the lungs. The diagnosis of atrioventricular septal defect can be made with 100% accuracy by an echocardiogram. Cardiac catheterization is done if there are any questions not clearly answered by the echocardiogram or if there is concern about pulmonary hypertension.

    How is AVSD treated?

    As described, surgery is almost always needed for children with AVSD. Treatment before surgery may involve controlling symptoms and promoting weight gain. Here are the primary treatment options explained:

    Pre-Surgery Treatment

    Control Symptoms of Congestive Heart Failure:

    • Heart Medicines: Digoxin (Lanoxin) and furosemide (Lasix) to manage heart function.
    • Potassium Level Maintenance: Spironolactone (Aldactone) is sometimes used to maintain potassium levels.
    • Blood Pressure Medicines: Captopril is used to lower blood pressure and reduce the heart's workload.

    Promote Weight Gain:

    • Nutritional Support: Richer formula or breast milk supplements are provided to ensure adequate calorie intake.
         Open-Heart Surgery
    • Timing: Ideally delayed until the child is around 4 to 6 months old to allow for growth, but can be done earlier if necessary.
    • Procedure Details:
      • Heart/Lung Bypass: Used to support circulation during the surgery.
      • Patch Placement: One or two patches are placed to divide the common valve into right and left sides and to close holes in the heart.
      • Valve Repair: Stitches are placed in the valve to decrease leakage.
    • Outcomes: Surgical results have continued to improve and the outlook is good for the

    Locations
    • Congenital Heart Center | Brighton Center for Specialty Care 7500 Challis Rd
      Entrance 1, Level 2
      Brighton, MI 48116-9416       Get Directions
    • Congenital Heart Center | C. S. Mott Children's Hospital 1540 E Hospital Dr
      Floor 11 Reception C
      Ann Arbor, MI 48109-4284       Get Directions
    • Michigan Heart and Vascular Specialists | Burns Professional Building 560 W Mitchell St Ste 400
      Petoskey, MI 49770-8895       Get Directions
    • Pediatric Cardiology Clinic | Munson Healthcare Pediatric Specialty Clinics 106 S Madison St
      Traverse City, MI 49684-2320       Get Directions
    • Pediatric Cardiology Clinic | Trinity Health Michigan Heart 5325 Elliott Dr Ste 201
      Ypsilanti, MI 48197-8633       Get Directions
    • Pediatric Cardiology Clinic | Trinity Health Oakland Hospital Medical Office Building
      44555 Woodward Avenue, Suite 105
      Pontiac, MI 48341       Get Directions
    • Pediatric Cardiology Clinic | U-M Health-Sparrow Professional Building 1200 E Michigan Ave Ste 715
      Ste 715
      Lansing, MI 48912-1832       Get Directions
    • Pediatric Cardiology | MyMichigan Medical Center Alpena 1501 W Chisholm
      Alpena, MI 49707       Get Directions
    • Pediatric Cardiology | UM Health-West Beltline Health Center 1310 East Beltline Ave SE
      Grand Rapids, MI 49506       Get Directions
    • Pediatric Congenital Heart Clinic | Northville Health Center 39901 Traditions Dr
      Floor 2
      Northville, MI 48168-9493       Get Directions

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