title: Increased systemic vascular resistance in neonates with pulmonary hypertension.
abstract: The time necessary for aortic diastolic pressure to decrease to 50 percent of an initially selected value after dissipation of the dicrotic notch (T 1/2) was determined in newborn infants with and without pulmonary hypertension. The mean T 1/2 was 671 +/- 167 msec in seven infants with clinical evidence of pulmonary hypertension and documented right to left ductus arteriosus shunting; 849 +/- 243 msec in nine infants with clinical evidence of pulmonary hypertension but no documented right to left ductus arteriosus shunting; and 457 +/- 66 msec in eight infants with hyaline membrane disease and no clinical evidence of pulmonary hypertension or a patent ductus arteriosus. The mean T 1/2 values in the former two groups were significantly different from that in the group with no pulmonary hypertension (P less than 0.01). An evaluation of factors affecting T 1/2 leads to the conclusion that the patients with pulmonary hypertension had increased systemic vascular resistance as well. This finding has important diagnostic, etiologic and therapeutic implications.
mesh_terms: D004373:Ductus Arteriosus / Q000503:physiopathology; D004374:Ductus Arteriosus, Patent / Q000503:physiopathology; D006801:Humans; D006819:Hyaline Membrane Disease / Q000150:complications / Q000503:physiopathology; D006976:Hypertension, Pulmonary / Q000151:congenital* / Q000209:etiology / Q000503:physiopathology; D007231:Infant, Newborn; D007232:Infant, Newborn, Diseases / Q000209:etiology / Q000503:physiopathology*; D008954:Models, Biological; D012127:Respiratory Distress Syndrome, Newborn / Q000150:complications / Q000503:physiopathology; D014655:Vascular Resistance