Clinical manifestations, pathophysiology, and diagnosis of atrioventricular (AV) canal defects
- Craig E Fleishman, MD
Craig E Fleishman, MD
- Associate Professor of Pediatrics
- University of Central Florida College of Medicine
- Aykut Tugertimur, MD, FACC
Aykut Tugertimur, MD, FACC
- Attending Pediatric Cardiologist
- Assistant Professor of Pediatrics
- Hofstra Northwell School of Medicine
- Section Editors
- John K Triedman, MD
John K Triedman, MD
- Section Editor — Pediatric Cardiology
- Professor of Pediatrics
- Harvard Medical School
- Heidi M Connolly, MD, FASE
Heidi M Connolly, MD, FASE
- Section Editor — Congenital Heart Disease
- Professor of Medicine
- Mayo Medical School
Atrioventricular (AV) canal defects are a group of congenital cardiac defects involving the AV septum and AV valves (ie, mitral and tricuspid valves). They are also referred to as AV septal defects, endocardial cushion defects, or persistent AV ostium. Combinations of these anatomic abnormalities result in complete (both atrial and ventricular septal defects [ASD/VSD]) and partial (only ASD) forms that are manifested in varying clinical presentations.
The anatomy, pathophysiology, clinical features, and diagnosis of AV canal defects will be reviewed here. The management and outcome of patients with AV canal defects are discussed separately. (See "Management and outcome of atrioventricular (AV) canal defects".)
AV canal defects account for about 4 to 5 percent of congenital heart defects with a reported prevalence of 0.3 to 0.4 per 1000 live births [1,2]. AV canal defects in fetuses accounted for a larger proportion of detected congenital heart disease (CHD), approaching 18 percent of CHD cases based on data from large fetal echocardiographic series [3,4]. The male-to-female distribution of AV canal defect is approximately equal , and complete AV canal defects with both atrial and ventricular septal defects occur in half of the cases [1,2].
There is a strong association between AV canal defects and trisomy 21 (also referred to as Down syndrome), with a 40 to 50 percent risk of Down syndrome in fetuses in whom an AV canal defect is detected . Nonsyndromic AV canal defects appear to be associated with maternal diabetes and obesity . (See 'Trisomy 21' below.)
Overview — AV canal defects encompass a broad range of AV septal defects and abnormalities of the AV valves. An initial classification separates the different types of AV canal defects based on anatomical features (eg, complete versus partial form) and their impact on physiology. In addition, variations of complete AV canal defects are categorized by AV valve morphology (Rastelli classification) and relative ventricular size. These classifications are used to guide surgical management.
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- Complete, partial, intermediate, and transitional forms
- Rastelli classification
- Balanced/unbalanced classification
- EMBRYOLOGY AND ANATOMY
- Normal development
- Anatomy of AV canal defects
- - AV valve abnormalities
- Complete AV canal defect
- Partial AV canal defect
- - Left ventricular outflow tract
- - Associated cardiac defects
- Molecular biology
- Trisomy 21
- Complete AV canal defect
- - Pulmonary hypertension and Down syndrome
- Partial AV canal defect
- Transitional AV canal defect
- AV valve regurgitation
- CLINICAL PRESENTATION
- Fetal presentation
- Postnatal presentation
- - Complete AV canal defect
- Heart failure
- Pulmonary vascular disease
- Unbalanced AV canal defect
- - Partial and transitional AV canal defect presentation
- - Left AV valve regurgitation
- - Radiography
- - Electrocardiography
- Fetal diagnosis
- Postnatal diagnosis
- - Echocardiography
- FURTHER EVALUATION
- - AV valve morphology
- - Ventricular size
- - Size of communication and shunting
- - Papillary muscle
- - Left and right ventricular outflow tract
- - Additional cardiovascular defects
- Cardiac catheterization
- DIFFERENTIAL DIAGNOSIS
- SUMMARY AND RECOMMENDATIONS