Effects of a chronic aortopulmonary shunt on pulmonary hemodynamics in piglets.
Systemic-to-pulmonary shunting in growing pigs has been proposed as an experimental model of high-flow pulmonary hypertension associated with congenital heart defects. We investigated multipoint pulmonary arterial pressure (Ppa) vs. cardiac output (Q) plots and pulmonary vascular impedance spectra in 13 piglets aged approximately 4 mo and ventilated alternatively in hyperoxia (inspired O2 fraction 0.4) and in hypoxia (inspired O2 fraction 0.12). The measurements were done 8 wk after either an anastomosis between the thoracic aorta and the pulmonary trunk (n = 7 piglets) or a sham operation (n = 6). Cardiac output was altered by a manipulation of venous return. In the sham-operated piglets, hypoxia increased Ppa by an average of 12 mmHg over the entire range of Q studied, from 60 to 120 ml/kg, and increased both 0 Hz (Z0) and characteristic (Zc) pulmonary vascular impedance. In the shunted piglets compared with the sham-operated piglets in hyperoxia, Ppa was increased by an average of 5-6 mmHg at all levels of Q studied, from 60 to 120 ml/kg (P < 0.01), and Zc was also increased (P < 0.01), whereas Z0 was unchanged. In the shunted piglets, hypoxia increased Ppa at all levels of Q studied only to an average of 3 mmHg, and neither Z0 nor Zc was altered by hypoxia. We conclude that an aortopulmonary shunt of 2-mo duration in growing pigs increases both pulmonary vascular resistance and impedance and is associated with a blunting of pulmonary vascular reactivity to hypoxia.
De Canniere
D
D
Laboratory of Cardiovascular and Respiratory Physiology, Erasme University Hospital, Brussels, Belgium.
Stefanidis
C
C
Brimioulle
S
S
Naeije
R
R
D000818:Animals; D001011:Aorta / Q000503:physiopathology; D001159:Arterio-Arterial Fistula / Q000503:physiopathology*; D001783:Blood Flow Velocity; D001794:Blood Pressure; D002302:Cardiac Output; D002908:Chronic Disease; D004195:Disease Models, Animal; D018496:Hyperoxia / Q000503:physiopathology; D006976:Hypertension, Pulmonary / Q000503:physiopathology*; D000860:Hypoxia / Q000503:physiopathology; D011651:Pulmonary Artery / Q000503:physiopathology*; D011652:Pulmonary Circulation / Q000502:physiology*; D013552:Swine; D014661:Vasoconstriction