Atrial septal defect physical examination
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Volume overload of the right side of heart can lead to right heart failure that may present with symptoms of swelling of the extremities, difficulty breathing and signs such as hepatomegaly and an elevated jugular venous pulse. On cardiovascular examinations there is a fixed splitting of second heart sound. Also, a systolic ejection murmur that is attributed to the increased flow of blood through the pulmonic valve can be heard.
The physical findings in an adult with an atrial septal defect depends on:
- Size of defect
- Degree of left-to-right shunt
- Pressure in pulmonary vasculature
- Any associated anomalies for e.g. mitral valve prolapse in ostium primum
- 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: An increased left-to-right atrial shunt can cause a hyperdynamic right ventricular flow that can be seen as precordial lift on inspection.
- Right ventricular impulse: An increased left-to-right atrial shunt can cause a hyperdynamic right ventricular impulse or heave. The heave can be best palpated at the 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 pronounced 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.
- Thrill: In large left-to-right shunt or the presence of a pulmonic stenosis a thrill can be palpated.
- First heart sound, S1
- Second heart sound, S2
- Best heard: at the second inter-costal space at the upper left sternal border.
- Fixed splitting of the second heart sound (S2) is present.
- It should be evaluated with the patient sitting or standing.
- Commonly seen with large left-to-right shunt and absence of pulmonary hypertension.
- 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 anatrial 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. Fixed splitting of S2 is rare with ASDs in newborns as they have little left-to right shunts.
Several different types of murmur can occur in atrial septal defect:
- Rumbling middiastolic murmur
- Crescendo-decrescendo systolic ejection murmur
- 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
- Pansystolic mitral regurgitation murmur
- Can be heard in ostium primum defects with accompanied cleft mitral valve or secundum defects with mitral valve prolapse.
- High pitched and blowing quality.
- Best heard with diaphragm of stethoscope with patient in left lateral dicubitus position.
- Usually best heard over the apical region with radiation to left axilla and left subscapular area.
- Posterior leaflet dysfunction murmur radiate to sternum or aortic area, anterior leaflet dysfunction murmur radiate to back.
- Left-to-right shunting of blood across the atria does not cause a murmur at the site of the shunt. This is so, because the pressure gradient between the atria are not high.
- Auscultatory findings in pulmonic regurgitation
- Widely split S2, S3 and S4 can be heard on auscultation. These heart sounds get accentuated with inspiration.
- Low-pitched murmur, best heard along the third or fourth intercostal spaces adjacent to the left sternal border.
- When the pulmonary artery systolic pressure exceeds 70 mm Hg, dilatation of the pulmonary artery ring may then result in Graham-Steell's murmur. This is a high-pitched, blowing decrescendo murmur heard best along the left parasternal region.
- 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-
- Cyanosis and clubbing in case Eisenmenger's syndrome develops.
- Holt-Oram syndrome can be associated with an ASD and the following skeletal abnormalities:
- 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.
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