PEDBASE.org - The Pediatric Database - Detailed information of ATRIAL SEPTAL DEFECT

ATRIAL SEPTAL DEFECT

DEFINITION:

An acyanotic congenital heart disease characterized by defects in the atrial septum.

EPIDEMIOLOGY:

incidence: 6-8% of all congenital cardiac lesions
age of first detection:
- heard as an innocent murmur in those <1 year but as an ASD in those >1year
risk factors:
- certain chromosomal and genetic disorders and syndromes

TYPES (3):

1. Ostium Secundum

an elliptical defect occurring at the site of the foramen ovale in the mid portion of the interatrial septum

2. Ostium Primum

a round defect occurring low in the septum
also known as an "incomplete endocardial cushion defect"
associated with clefts of the mitral and tricuspid valves

3. Sinus Venosus

an oval or round defect occurring high in the septum
associated with anomalous drainage of the veins of the RUL

PATHOGENESIS:

1. Background

early after birth the right ventricle is thick and less compliant and so there is a small pressure differential between the right and left atria. As the infant gets older, the RV wall thins as the pulmonary vascular resistence decreases and so a left -> right shunt develops. This increases the pulmonary blood flow (to 2-5x that of the systemic blood flow) but because the pulmonary vascular resistence remains low, the pulmonary arterial pressure remains normal.

CLINICAL FEATURES:

1. Symptoms

1. Asymptomatic

small defects with trivial left->right shunt
usually found on routine physical examination

2. Symptomatic

large defects with significant pulmonary hypertension
- congestive heart failure
- dyspnea (exertional)
- failure to thrive
- fatigue or palpitations (due to arrhythmias, i.e., AF)
- feeding difficulties
- profuse perspiration
- recurrent lung infections

2. Signs

1. Periphery

normal

2. Palpation

parasternal lift (RVH)
- @ LLSB with medial migration of apex (RVH)

3. Auscultation

1. Heart Sounds

1. S1 - normal

2. S2 - loud @ ULSB

widely split +/- fixed in all phases of respiration (due to a prolonged RV ejection time due to increased RV blood volume)

2. Murmurs

1. Systolic

1. Pulmonary Flow Murmur

SEM @ L 2nd interspace near sternum
medium-pitched of varying intensity
increased flow across the pulmonary valve

2. Mitral Valve Insufficiency

regurgitant murmur at apex -> axilla
cleft in medial leaflet of mitral valve

2. Diastolic

1. Relative Tricuspid Stenosis

low-pitched & rumbling @ LLSB

INVESTIGATIONS:

1. Chest X-Ray

RAH, RVH, increased PA & vascularity

2. ECG

classically: 1st degree heart block, RBBB, RVH
RAD, RAH

3. 2D-Echo

ASD, RV volune overload, paradoxal ventricular septal motion

MANAGEMENT:

1. Supportive

ASD's are well tolerated during childhood and there is no need for restriction of activity

1. Medical Management

1. Antibiotic Prophylaxis

adenoidectomy
dental surgery
oropharyngeal surgical procedures
any instrumentation of the genitourinary and lower intestinal tracts

2. Congestive Heart Failure

digoxin and lasix

2. Surgery

1. Indications for:

all ASD's are surgically repaired
- with increasing age (4th and 5th decades) there is an increased operative risk, increased pulmonary artery pressure, and more severe symptoms such as arrhythmias (PAT, AF, atrial flutter)
prior to entry into school (3-5 years of age) if asymptomatic
sooner if symptomatic

2. Types

1. Complete Repair

2. Devise Repair

3. Complications

mortality: 1.1%

3. Prognosis

95% of ASD's remain open while 5% close spontaneously
refer to cardiologist at 3 years of age unless symptomatic (due to complications of a L -> R shunt):
- congestive heart failure
- failure to thrive
- increasing pulmonary pressures
- other cardiac defects
- recurrent respiratory infections
patients with Trisomy 21 are at increased risk for the development of pulmonary hypertension

Pediatric Database - ATRIAL SEPTAL DEFECT

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