Morphology of the elastic pulmonary arteries in pulmonary hypertension: a quantitative study

Recent studies of intravascular ultrasound of the pulmonary arteries sugges t that the technique can detect intimal and medial thickening in patients w ith pulmonary hypertension, potentially providing a method of assessing sev erity of pulmonary vascular disease in life. A major drawback of the techni que is that only the elastic pulmonary arteries are accessible to current u ltrasound catheters. The aim of this study was to determine whether morphol ogical changes in vessels accessible to intravascular imaging reflect sever ity of pulmonary vascular disease and are of a sufficient degree to be dete ctable by current ultrasound catheters. Morphometric studies of the elastic pulmonary arteries were performed in specimens of lungs from 24 patients w ho had died with pulmonary hypertension (aged 3 weeks-9 years) and compared with measurements from infants who had died from sudden infant death syndr ome. Morphological changes evident in the elastic pulmonary arteries in pul monary hypertension included luminal dilation and medial thickening but the se changes were too variable to be predictive of the severity of peripheral pulmonary vascular disease. Intimal thickening and atherosclerosis were pr esent only in those with advanced pulmonary hypertensive disease. The chang es of medial thickening and luminal dilation, nonetheless, are too variable to be predictive of the severity of peripheral pulmonary vascular disease. Thus, imaging by intravascular ultrasound may help confirm advanced pulmon ary vascular disease, but is unlikely to differentiate less severe pulmonar y vascular disease when the patient may still potentially be operable.