Abstract
In congenital heart disease with large shunts at the ventricular or arterial level the mean pulmonary artery pressure is increased to systemic levels. In addition, these shunts also increase the pulse pressure (PP) in the pulmonary arteries; the increased pulsatility, acts apart from mean pressure. Increased PP injures the arterial wall from exaggerated distension with each heart beat, producing medial hypertrophy that narrows the lumen, increasing pulmonary vascular resistance--a positive feedback. Thus, pulmonary arterial hypertension (PAH) is progressive and surgical intervention was considered dangerous. However we have observed adults with PAH who are stable and asymptomatic; they had central PAH but the pressure was reduced in the distal pulmonary arteries by valvular or bilateral distal stenosis. We present brie fl y two adults: one illustrates the stabilizing effect of damping pulsatility in the pulmonary arteries, and the second illustrates the catastrophic effects of excessive pulsatility from a shunt. Recently, surgical advances have demonstrated that stabilization of patients with a large ventricular septal defect by short term surgical banding can be achieved with modest mortality, adding pre- and post-operative pharmacologic vasodilators, such as calcium channel blockers, nitric oxide, acetylcholine, endothelin receptor antagonists, and prostacyclin. Excess PP has also been recognized to cause vascular injury in the systemic circulation predicting adverse cardiovascular outcomes, unaffected by current antihypertensive therapy. Perhaps increased PP in the systemic circulation might respond to pharmacologic measures that have been successful with PAH.
Highlights
Pulmonary arterial hypertension (PAH) is normally present in the first few days after birth, and positive remodeling occurs rapidly so that after 3 days the pulmonary artery pressure is less than onefifth of the systemic
We have observed a few patients with a large ventricular septal defects (VSD) and mean PAH who have done much better; they had dampening of pulse pressure (PP) in the pulmonary arteries from mild pulmonic stenosis. (Severe stenosis would result in a tetrad physiology with mean pulmonary artery pressures below normal.) We have observed an adult tetrad of Fallot who received an overly large shunt to the pulmonary circuit resulting in an acute Eisenmenger syndrome
Six to 16 years after closure of the VSD, all led normal lives with satisfactory exercise tolerance. With exercise their pulmonary artery pressures rose, there was no progression of their PAH, indicating that stability of the pulmonary vasculature was possible after reduction of the high PP
Summary
Pulmonary arterial hypertension (PAH) is normally present in the first few days after birth, and positive remodeling occurs rapidly so that after 3 days the pulmonary artery pressure is less than onefifth of the systemic. Large ventricular septal defects (VSD) and arterial ducts transmit systemic pressure to the right ventricle from birth, creating pulmonary hypertension (PAH) with increased pulsatility. If the VSD is not closed, the PAH will lead eventually to Eisenmenger syndrome, characterized by obstructive lesions in the pulmonary arteries with a marked increase in pulmonary vascular resistance. We have observed a few patients with a large VSD and mean PAH who have done much better; they had dampening of PP in the pulmonary arteries from mild pulmonic stenosis. (Severe stenosis would result in a tetrad physiology with mean pulmonary artery pressures below normal.) We have observed an adult tetrad of Fallot who received an overly large shunt to the pulmonary circuit resulting in an acute Eisenmenger syndrome. A review of publications follows, assessing the role of pulsatility injury in both pulmonary and systemic vasculature, and the stabilizing effect on the pulmonary artery pressure after surgical banding and repair
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