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Pulmonary stenosis with interatrial communication
Historical Notes
In 1769, Giovanni Battista Morgagni described pulmonary stenosis with a patent foramen ovale, and in 1848 Thomas Peacock described Contraction of the Orifice of the Pulmonary Artery and Communication Between the Cavities of the Auricles by a Foramen Ovale.
Pulmonary stenosis with reversed interatrial shunt has been called the trilogie de Fallot. Right ventricular outflow obstruction resides in a stenotic mobile dome-shaped pulmonary valve ( Fig. 13.1 ) and is occasionally represented by stenosis of the pulmonary artery and its branches ( Fig. 13.2 ). Infundibular obstruction takes the form of secondary hypertrophic subpulmonary stenosis ( Fig. 13.3 ). The interatrial communication is a patent foramen ovale or an ostium secundum atrial septal defect, , less commonly by an ostium primum or sinus venosus atrial defect, or much less commonly by anomalous pulmonary venous connection. This chapter deals with pulmonary valve stenosis and a patent foramen ovale or a nonrestrictive ostium secundum atrial septal defect.
Lateral right ventricular angiocardiogram (RV) from a 2-day-old male with pinpoint pulmonary valve stenosis, reversed shunt through a patent foramen ovale, and tricuspid regurgitation. The arrow identifies a tiny jet into a dilated pulmonary trunk (PT).
X-rays from a 5-year-old male with stenosis of the pulmonary arterial branches (gradient 50 mm Hg) and a 2.2 to 1 left-to-right shunt through an ostium secundum atrial septal defect. (A) Posteroanterior projection shows vascular lung fields, moderate dilation of the pulmonary trunk, an inconspicuous ascending aorta, and a prominent right atrial convexity. (B) Angiocardiogram with contrast material injected into the pulmonary trunk delineates stenoses of the right and left pulmonary arteries (arrows) with distal dilatation.
(A) Lateral right ventricular angiocardiogram in a 5-year-old female with severe mobile pulmonary valve stenosis (PV) and secondary dynamic systolic narrowing of the infundibulum (Inf) . There was a 1.4 to 1 left-to-right shunt through an atrial septal defect despite suprasystemic right ventricular systolic pressure. The pulmonary trunk (PT) was dilated. (B) Infundibular narrowing disappeared during diastole (arrow). RV , Right ventricle.
Anatomic considerations
Severe pulmonary valve stenosis with a right-to-left shunt through a patent foramen ovale is more common than pulmonary valve stenosis with a nonrestrictive atrial septal defect, irrespective of the direction of the shunt. A restrictive interatrial communication is almost always a patent foramen ovale, the shunt is right-to-left, and pulmonary stenosis is necessarily severe. , A nonrestrictive interatrial communication is almost always an ostium secundum atrial septal defect, the shunt is left-to-right, and pulmonary stenosis is necessarily mild to moderate. , ,
Physiologic consequences
The physiologic consequences of pulmonary stenosis with an interatrial communication depend on the degree of obstruction to right ventricular outflow and the size of the interatrial communication. , Patients with pulmonary stenosis and a right-to-left interatrial shunt ( Fig. 13.4 ) almost always have a severely stenotic pulmonary valve and a patent foramen ovale (see earlier). Patients with pulmonary stenosis and a left-to-right interatrial shunt almost always have a mild to moderate pulmonary valve stenosis and a nonrestrictive ostium secundum atrial septal defect (see earlier).
Severe pulmonary stenosis with right ventricular hypertrophy results in an increase in force of right atrial contraction ( Figs. 13.5 and 13.6 ) that generates a presystolic right-to-left interatrial shunt. High right atrial pressure stretches the margins of the foramen ovale and increases its patency. Increased right atrial pressure thus increases the risk of paradoxic emboli across an atrial septal defect or patent foramen ovale. When right atrial blood escapes through the interatrial communication, pulmonary flow tends to fall reciprocally.
A nonrestrictive atrial septal defect with a large left-to-right shunt and mild to moderate pulmonary valve stenosis clinically resembles an isolated atrial septal defect (see Chapter 12 ). The small gradients generated by hyperkinetic right ventricular ejection across a normal pulmonary valve can generate a small gradient that should not be mistaken for mild pulmonary stenosis.
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