Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content +++ KEY FEATURES +++ ESSENTIALS OF DIAGNOSIS ++ Widely fixed split S2 Midsystolic murmur Diastolic flow rumble at the lower left sternal border if the shunt is large Incomplete right bundle branch block (RBBB) with vertical QRS axis (ostium secundum ASD) and superior axis (ostium primum ASD) on ECG Prominent pulmonary arteries and right ventricular (RV) enlargement RV dilatation, increased pulmonary artery flow velocity, and left-to-right atrial shunt by Doppler echocardiography Oxygen step-up within the right atrium; right-sided catheter can pass into the left atrium across the defect +++ GENERAL CONSIDERATIONS ++ Most common congenital lesion in adults (after bicuspid aortic valve) Classification is according to location Secundum ASD (most common) is a defect involving the septum secundum in the region of the fossa ovalis Primum ASD (also called atrioventricular [AV] canal defect) involves the ostium primum in the lower portion of the atrial septum Sinus venosus ASD is a defect that can be located either superiorly near the superior vena cava or inferiorly near the inferior vena cava. ASD is often asymptomatic and undiagnosed until adulthood The pathophysiologic consequences depend on the quantity of blood shunted from the systemic to pulmonary circulation +++ CLINICAL PRESENTATION +++ SYMPTOMS AND SIGNS ++ Usually no symptoms in the young adult with an ASD and normal pulmonary artery pressures unless the defect is very large Symptoms more common in the fourth or fifth decade Dyspnea Diminished exercise tolerance Atrial arrhythmia increases with age and may be the most common presenting symptom in patients over 50 Signs and symptoms of RV failure due to pulmonary hypertension or longstanding volume overload +++ PHYSICAL EXAM FINDINGS ++ Prominent RV impulse Palpable pulmonary artery Systolic ejection murmur that does not vary with respiration Wide, fixed split S2 Right-sided diastolic flow rumble Right-sided S3 gallop Holosystolic murmur of mitral regurgitation with ostium primum ASD With pulmonary hypertension, the P2 is usually increased and a diastolic murmur of pulmonic insufficiency may be audible (Graham Steell murmur) Signs of RV failure with elevated jugular venous pressure and venous congestion in late stages Cyanosis in patients with Eisenmenger physiology +++ DIFFERENTIAL DIAGNOSIS ++ Other causes of exertional dyspnea, of atrial arrhythmias, of RV failure, and of a midsystolic murmur (eg, pulmonic stenosis) The wide fixed split S2 can be mimicked by complete RBBB, pericardial knock, and a late systolic click Other causes of pulmonary hypertension +++ DIAGNOSTIC EVALUATION +++ ELECTROCARDIOGRAPHY ++ Incomplete RBBB in 90% of cases Right axis deviation with ostium secundum and sinus venosus ASDs First-degree AV block, complete RBBB, and left anterior fascicular block with superior and leftward axis with primum ASDs Ectopic atrial rhythm with superior P-wave axis occasionally with sinus venosus ASD RV ... Your Access profile is currently affiliated with [InstitutionA] and is in the process of switching affiliations to [InstitutionB]. Please select how you would like to proceed. Keep the current affiliation with [InstitutionA] and continue with the Access profile sign in process Switch affiliation to [InstitutionB] and continue with the Access profile sign in process Get Free Access Through Your Institution Learn how to see if your library subscribes to McGraw Hill Medical products. Subscribe: Institutional or Individual Sign In Error: Incorrect UserName or Password Username Error: Please enter User Name Password Error: Please enter Password Sign in Forgot Password? Forgot Username? Sign in via OpenAthens Sign in via Shibboleth You already have access! Please proceed to your institution's subscription. Create a free profile for additional features.