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
On physical examination, a patient with an atrial septal defect may present with a crescendo-decrescendo systolic ejection murmur and widely fixed split S2.
Physical examination
The physical findings in an adult with an atrial septal defect depends on:
- The degree of left-to-right intracardiac shunt
- Size of defect
- Associated anomalies
General physical examination
- Cyanosis and clubbing in case Eisenmenger's develops.
- Underdevelopment/below-average size for age.
Cardiovascular examination
- Precordial inspection
- Precordial bulge- The left-to-right shunting of blood causes right atrial enlargement that can present as a precordial bulge. The precordial bulge can cause a counter development of Harrison's groove that are horizontal depressions along the sixth and seventh costal cartilages at the lower margin of the thorax where the diaphragm attaches to the ribs.
- Precordial lift
- Precordial palpation
- Right ventricular impulse or heave - An increased left-to-right atrial shunt can cause a hyperdynamic right ventricular impulse or heave. The heave can be best palpated at left sternal border or the subxiphoid area.
- Pulmonary artery pulsations- Pulsatile, enlarged pulmonary artery pulsation can be felt at the second left intercostal space. These are more prononuced in patients with large left-to-right shunts. Patients with obstruction to right ventricular outflow have a less dynamic right ventricular impulse and may present with more of a tapping or thrusting quality.
- In large left-to-right shunt or the presence of a pulmonic stenosis a thrill can be palpated.
Auscultation
- First heart sound, S1
- Best heard at apex
- Can be split. The reason behind the split is that the large volume of diastolic blood flow from right atrium to right ventricle causing forceful contraction of the tricuspid leaflets
- Second heart sound S2
- Fixed splitting of the second sound (S2). Commonly seen in individuals with large left-to-right and absence of pulmonary hypertension.
- Best heard at second intercostal space.
- It should be evaluated with the patient sitting or standing.
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. 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. The reason for a fixed splitting second heart sound is that: Normally the pulmonary component of S2 occurs after the aortic component A2 (due to difference in compliance and resistance in the two sides). This separation ("splitting") of S2 increases with inspiration. Fixed splitting of S2 is rare with ASDs in newborns as they have little left-to right shunts.
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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:
- Midsystolic pulmonary flow or ejection murmur.
- Heard best at 2nd intercostal space at upper left sternal border.
- Heard commonly in moderate to large left-to-right shunts
- Occur due to increased right ventricular stroke volume across pulmonary outflow tract
- Systolic crescendo-decrescendo murmur
- Audible over the lung fields and is thought to occur from rapid flow through the peripheral pulmonary arteries
- Pansystolic mitral regurgitation murmur
- Can be heard in ostium primum defects with accompanied cleft mitral valve or ostium secundum defects with mitral valve prolapse.
- Murmur radiation to the axilla.
- Rumbling middiastolic murmur
- Heard best at the lower left sternal border because of increased flow across the tricuspid valve.
- Commonly heard with large left-to-right shunts
- Low-to-medium frequency
- Pulmonic regurgitation
- Low-pitched diastolic murmur
- caused by pulmonary artery dilatation
- Patients with pulmonary arterial hypertension and right ventricular hypertrophy- S4 may be present, narrow S2 splitting with accentuated pulmonic component, and murmur of pulmonic regurgitation may be audible.
Auscultatory findings in pulmonary hypertension
Left-to-right shunt in atrial septal defect causes increased flow through the pulmonary vasculature, which can lead to pulmonary hypertension. This pulmonary hypertension may finally cause increased pressures in the right side of the heart and reversal of the shunt into a right-to-left shunt. Auscultatory findings accompanying pulmonary hypertension are-
- Increased intensity of the pulmonic component of S2, but no fixed splitting
- Fourth heart sound (right ventricular)
- Midsystolic ejection click
- Absence of tricuspid flow murmur
- A holosystolic murmur of tricuspid insufficiency
- Midsystolic pulmonic murmur
- A high pitched pulmonic regurgitation murmur
Eisenmenger's syndrome
Eisenmenger's syndrome is defined as the process in which a left-to-right shunt in the heart causes increased flow through the pulmonary vasculature, which leads to pulmonary hypertension, which finally causes increased pressures in the right side of the heart and reversal of the shunt into a right-to-left shunt. This right to left shunt causes the patient to become cyanotic. Thus, Eisenmenger's syndrome is said to develop when there is a pulmonary artery disease, right-to-left heart shunting and cyanosis
General physical examination
- Central cyanosis
- Clubbing
Signs of increased right atrial pressure
- Jugular venous pressure may be raised with 'a' wave indicating increased right atrial pressure. A "v" wave indicating development of tricuspid regurgitation may also be seen
- Peripheral edema
- Hepatomegaly
- Ascites
Cardiovascular examination
- Right ventricular heave and thrill
- Murmurs of tricuspid and pulmonic regurgitation maybe audible.
Extracardiac features
- Deformed carpal bones
- Deformed thumbs
- Holt-Oram syndrome
- Deformed radial bones
- Paradoxical embolization