Acute PAH was induced by microbead injection in six female beagles (8.3 ± 2.4 kg body weight). The sequence of experimental procedures is outlined in Fig. 1.
General anesthesia was induced in all dogs by intraveneous propofol injection (10 mg/kg body weight). After endotracheal intubation, anesthesia was maintained with isoflurane (1–3%) in 100% oxygen using mechanical ventilation at a respiratory frequency of 11 breaths/min. Lactated Ringer’s solution was infused at a rate of 10 mL/kg/h. A femoral arterial catheter was inserted and systemic arterial pressure (SAP) and arterial blood gases were monitored. The femoral and external jugular veins were catheterized for RHC access, delivery of emboli, delivery of contrast for angiography and blood sampling. Thirty minutes after the stabilization of the animals, baseline CO, SAP, PAP (systolic, diastolic, mean), pulmonary capillary wedge pressure (PCWP), RV pressure, and right atrial pressure were measured.
While maintaining the dog under anesthesia, magnetic resonance imaging (MRI) and right heart catheterization (RHC) were repeated twice, first to obtain baseline vitals, pressures, RV function, and large PA geometry in the healthy animal (PRE tests), and second to measure the same parameters after acute PAH was successfully induced by embolization (POST tests). Dogs were humanely euthanized after the POST tests. All the procedures were approved by the Institutional Animal Care and Use Committee (IACUC) of the University of Wisconsin-Madison.