Atrial septal defect physical examination
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editors-In-Chief: Priyamvada Singh, M.B.B.S. [[2]]; Cafer Zorkun, M.D., Ph.D. [3]; Assistant Editor-In-Chief: Kristin Feeney, B.S. [[4]]
Overview
Upon physical examination, a patient with an atrial septal defect may present with an ejection systolic murmur caused by the fixed splitting of S2.
Physical examination
The physical findings in an adult with an ASD include those related directly to:
- The degree of left-to-right intracardiac shunt
- Size of defect
- Right heart failure
Cardiovascular examination-
- Shunting of blood from left-to-right side of heart causes increased right sided stroke volume and hyper-dynamic right ventricular impulse.
- Pulmonary artery dilatation can lead to palpable pulsation of the pulmonary artery and ejection click
- Heart sound- S1 is typically split
Increased S2 intensity, (due to increased right ventricular contraction)
Widely fixed split S2 ( occur due to reduced respiratory variation due to delayed pulmonic valve closure
- Murmur-
- Crescendo-decrescendo systolic ejection murmur.
- Heard best at 2nd intercostal space at upper left sternal border.
- Occur due to increased right ventricular stroke volume across pulmonary outflow tract
- Rumbling middiastolic murmur
- In large left-to-right shunts
- Heard best at the lower left sternal border because of increased flow across the tricuspid valve.
Murmurs
During auscultation of the heart, a clinician may find evidence of abnormal heart sounds produced by a cardiac murmur. Atrial septal defect, being a condition that directly influences the hemodynamics between the right and left ventricle, has multiple types of associated murmurs such as:
- Systolic murmurs
- Systolic ejection murmur/midsystolic pulmonary flow - caused by the increased flow of blood through the pulmonic valve rather than any structural abnormality of the valve leaflets.
- Audible when ausculating over the second intercostal space
- Only associated with a thrill when there is a very large left-to-right shunt or the presence of a pulmonic stenosis
- Systolic crescendo-descrendo murmur - caused by the rapid flow of blood through the peripheral pulmonary arteries.
- Audible, over the lung fields
- Mitral regurgitation murmur - caused by one of two conditions:
- In ostium primum defects, it is the cleft mitral valve
- In ostium secundum defects, it is the mitral valve prolapse where the holosystolic murmur of the mitral regurgitation emitting to the axilla is audible
- Diastolic murmurs
- Mid-diastolic murmur (low-to-medium frequency) - caused by a high flow of blood across the tricuspid valve
- Not influenced by inspiration
- Left-to-right shunt greater than a ratio of 2:1
- Pulmonic regurgitation (low-pitched diastolic) murmur - caused by pulmonary artery dilatation
Cardiac Sounds
Fixed Splitting of S2
<youtube v=5tBk1XuEyuM/> In individuals with an atrial septal defect, there is a fixed splitting of S2. Fixed splitting occurs as a result of the extra blood return during inspiration equalized by the intraseptal communication between the left and right atrium allowed by the defect.
In unaffected individuals, there are respiratory variations in the splitting of the second heart sound (S2). During respiratory inspiration, the negative intrathoracic pressure causes increased blood return into the right side of the heart. The increased blood volume in the right ventricle causes the pulmonic valve to stay open longer during ventricular systole. This causes a normal delay in the P2 component of S2. During expiration, the positive intrathoracic pressure causes decreased blood return to the right side of the heart. The reduced volume in the right ventricle allows the pulmonic valve to close earlier at the end of ventricular systole, causing P2 to occur earlier.
Common Findings
In symptomatic cases, common findings during a physical examination include:
- Presence of pulmonary hypertension
- Precordial palpation
- Atrial enlargement can cause a precordial bulge that makes Harrison's groove, which are a horizontal line at the lower margin of the thorax where the diaphragm attaches to the ribs, founds along the sixth and seventh costal cartilages.
- A hyperdynamic impulse in the right ventricle can cause a right ventricular heave where there is an increased diastolic filling and large stroke volume, found along the left sternal board and subxiphoid area.
- Pulsatile, enlarged pulmonary artery palpation can be felt at the second left intercostal space where a more pronounced pulse may be felt if pulmonary hypertension is present
- Underdevelopment/below-average size for age
- Extrcardiac features:
- Deformed carpal bones
- Deformed thumbs
- Holt-Oram syndrome
- Deformed radial bones