Atrial septal defect

Published on 05/05/2015 by admin

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Last modified 05/05/2015

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22 Atrial septal defect

Instruction

Examine this patient’s heart.

Listen to her heart.

Salient features

History

Ostium secundum defect (anatomically in the region of the fossa ovalis)

• Asymptomatic particularly small defects with minimal left to right shunting; moderate or large defects often have no symptoms until third or fourth decades despite substantial left-to-right shunting (characterized by a ratio of pulmonary to systemic flow of 1.5 or more)

• Fatigue

• Dyspnoea

• Palpitations indicating atrial arrhythmias

• Productive cough indicating recurrent pulmonary infections

• Symptoms of paradoxical emboli

• Right heart failure.

Ostium primum defect (anatomically in the lower part of the atrial septum)

• Patients may develop symptoms and heart failure in childhood

• Failure to thrive

• Chest infections

• Poor development

• In adults in addition to the same symptoms as for secundum defect, the following occur:

• Syncope: indicating heart block
• Symptoms suggesting endocarditis.

Examination

• Diffuse or normal apical impulse

• Left parasternal heave

• Ejection systolic flow murmur in the left second and third intercostal space

• Wide, fixed, split second heart sound (occasionally a slight movement of P occurs) that does not vary with respiration (Fig. 22.1)

• Infrequently, a mid-diastolic murmur may be heard in the tricuspid area (indicating a large left-to-right shunt)

• Proceed by looking for signs of:

• pulmonary hypertension (Eisenmenger syndrome)
• congenital defects of the thumb (Holt–Oram syndrome).
image

Fig. 22.1 Auscultatory findings resulting from an atrial septal defect. S1, first heart sound; A2, aortic valve closure; P2; pulmonic valve closure.

Note: Atrial secundum defect is often confused with pulmonary stenosis (P is soft, delayed and moves with respiration).

Diagnosis

This patient has an atrial septal defect (ASD) (lesion) that is congenital in origin (aetiology); she is not in cardiac failure and there is no reversal of shunt (functional status).

Advanced-level questions

What are the types of atrial septal defect

• Ostium secundum defect accounts for 70% of the cases. The defect is in the middle portion of the atrial septum and is usually 2–4 cm in diameter (incomplete right bundle branch block pattern, QRS axis rightward) (Fig. 22.2A,B).

• Sinus venosus type is a defect in the septum just below the entrance of the superior vena cava into the right atrium (leftward P wave axis so that P waves are inverted in at least one inferior lead) (Fig. 22.2C).

• Ostium primum type is a defect in the lower part of the septum and clefts may occur in the mitral and tricuspid valves (QRS axis leftward). A junctional or low atrial rhythm (inverted P waves in the inferior leads) occurs with sinus venosus defects.

image

Fig. 22.2 Electrocardiography in atrial septal defect. (A,B) Ostium secundum defect right precordial leads V1 and V2 illustrate two variants of an incomplete right bundle branch block pattern, the rSrT pattern (A) and the rsR’ pattern (B). (C) Ostium primum type: endocardial cushion defect with the QRS axis is leftward counterclockwise and superior.

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