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Pediatric Unbalanced Atrioventricular Septal Defects Clinical Presentation

  • Author: Mark A Law, MD; Chief Editor: Howard S Weber, MD, FSCAI  more...
Updated: Jan 04, 2016


Infants with unbalanced atrioventricular (AV) septal defects generally present in the first month of life with congestive heart failure (CHF) with tachypnea and failure to thrive due to pulmonary overcirculation, if no significant right-sided or left-sided obstruction is present.

If pulmonary outflow tract obstruction is present, infants may present with cyanosis or an audible murmur.

Occasionally, neonates may present in extremis with acidosis in the presence of ductal-dependent systemic circulation or cyanosis in the presence of ductal-dependent pulmonary circulation.

Patients with abdominal heterotaxy may present with situs inversus incidentally noted on routine chest radiography.



Note the following:

  • Most children appear healthy, except the rare patient with features of Down syndrome.
  • This lesion is associated with various auscultatory findings, depending on the underlying physiology.
  • Murmurs of pulmonary stenosis, left ventricular (LV) outflow tract obstruction, or atrioventricular valve (AVV) regurgitation may be appreciated.[9]
  • Cyanosis may be present.
  • Reduced lower extremity pulses may suggest coarctation of the aorta, which may coexist with right ventricle (RV)–dominant atrioventricular canal (AVC).


The genetic basis for this lesion has not been elucidated; however it can be associated with trisomy 21.

Unbalanced AV septal defect may be observed in patients with abdominal heterotaxy. The presence of complete AV septal defect is more than twice as frequent in patients with asplenia than in those with polysplenia.

Contributor Information and Disclosures

Mark A Law, MD Associate Professor of Pediatrics, Fellowship Director of Pediatric Cardiology, Department of Pediatric Cardiology, University of Alabama School of Medicine

Mark A Law, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Pediatrics, American College of Cardiology, American College of Physicians, American Heart Association

Disclosure: Nothing to disclose.

Specialty Editor Board

Mary L Windle, PharmD Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Nothing to disclose.

Hugh D Allen, MD Professor, Department of Pediatrics, Division of Pediatric Cardiology and Department of Internal Medicine, Ohio State University College of Medicine

Hugh D Allen, MD is a member of the following medical societies: American Academy of Pediatrics, American Society of Echocardiography, Society for Pediatric Research, Society of Pediatric Echocardiography, Western Society for Pediatric Research, American College of Cardiology, American Heart Association, American Pediatric Society

Disclosure: Nothing to disclose.

Chief Editor

Howard S Weber, MD, FSCAI Professor of Pediatrics, Section of Pediatric Cardiology, Pennsylvania State University College of Medicine; Director of Interventional Pediatric Cardiology, Penn State Hershey Children's Hospital

Howard S Weber, MD, FSCAI is a member of the following medical societies: American Academy of Pediatrics, American College of Cardiology, Society for Cardiovascular Angiography and Interventions

Disclosure: Received income in an amount equal to or greater than $250 from: St. Jude Medical.

Additional Contributors

Paul M Seib, MD Associate Professor of Pediatrics, University of Arkansas for Medical Sciences; Medical Director, Cardiac Catheterization Laboratory, Co-Medical Director, Cardiovascular Intensive Care Unit, Arkansas Children's Hospital

Paul M Seib, MD is a member of the following medical societies: American Academy of Pediatrics, American College of Cardiology, American Heart Association, Arkansas Medical Society, International Society for Heart and Lung Transplantation, Society for Cardiovascular Angiography and Interventions

Disclosure: Nothing to disclose.


Ameeta Martin, MD Clinical Associate Professor, Department of Pediatric Cardiology, University of Nebraska College of Medicine

Ameeta Martin, MD is a member of the following medical societies: American College of Cardiology

Disclosure: Nothing to disclose.

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Echocardiogram image revealing a left ventricular dominant atrioventricular (AV) canal defect.
Catheterization in a patient with a left ventricular (LV)–dominant atrioventricular (AV) canal defect. The catheter is positioned in the pulmonary artery demonstrating pulmonary artery band and branch pulmonary arteries.
ECG of a 3-month-old female with a left ventricular (LV)–dominant atrioventricular (AV) canal. The ECG reveals left axis deviation with an initial counterclockwise frontal loop.
Echocardiogram clip demonstrating common atrioventricular (AV) valve regurgitation in a patient with a left-ventricular (LV)–dominant AV canal defect.
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