Ultrasound navigation through the Heart for off-pump aortic valved stent implantation : New tools for new goals.

PURPOSE: To validate the use of simultaneous intracardiac and intravascular ultrasound (IVUS) guidance for periprocedural dimension assessment, Residual-Coronary/Sinus-Stent Index (RCSSI) estimation, target site identification, deployment monitoring, and quality control of off-pump aortic Valved Stent implantation. METHODS: Five pigs (56+/-5 kg) underwent off-pump orthotopic aortic valve implantation using a custom-made self-expanding Valved Stent. Intracardiac ultrasound (AcuNav) was introduced via the right femoral vein. After left-sided thoracotomy, pursestring sutures were placed on the left ventricular apex. Following heparinization, a guidewire was inserted through the apex and advanced over the aortic valve under fluoroscopy. A wire-guided IVUS catheter transducer (6-F, 12.5-MHz) was inserted and the aortic target site identified. IVUS probe location was tracked with AcuNav, and measures of the aortic root were taken by both. After removal of the IVUS, the Valved Stent delivery system was introduced over the guidewire under fluoroscopy and AcuNav monitoring; the Valved Stent was deployed over the native valves. In vivo assessment included leaflet motion, planimetric valve orifice and RCSSI (stent to aortic wall distance/coronary diameter) calculations, coronary blood flow characteristics, transvalvular gradient, regurgitation, and paravalvular leaking in combination with continuous cardiac output measures. Macroscopic analysis was performed at necropsy. RESULTS: IVUS dimensions of the aortic root were equal to AcuNav and necropsy dimensions. Both tools showed good valvular function, with full valvular opening and closing in 3 of 5 valves. At necropsy, the 3 aortic Valved Stents were safely anchored. One Valved Stent was placed supra-annularly; 2 dislodged into the left ventricle because of size mismatch. One Valved Stent showed a moderate to severe paravalvular leak. CONCLUSIONS: Simultaneous intracardiac and intravascular ultrasound-guided off-pump orthotopic aortic Valved Stent implantation via left sided thoracotomy is feasible in an animal model. IVUS and intracardiac ultrasound allow adequate aortic dimension assessment and Valved Stent delivery monitoring, as well as postimplantation coronary flow evaluation

Aqueous oxygen : the solution to relief hypoxic pulmonary hypertension.

OBJECTIVE: To evaluate the effects of hyperbaric oxygen solution on hypoxic pulmonary hypertension. METHODS: Eleven calves, 2-month-old, 71+/-6 kg, underwent general anaesthesia, mechanical ventilation and median sternotomy. Catheters for continuous pressure and blood gas measurements were inserted in carotid and femoral arteries, left atrium, right atrium and pulmonary artery (PA), and a flow-probe placed around the PA. After baseline measurements 30 min hypoxic ventilation reduced the mean arterial PO2 from 285+/-115 to 46+/-11 mmHg (P < 0.0001). At this point, without changes in hypoxic ventilation (mean arterial PO2 maintained at 50+/-5 mmHg), 3 ml/min of hyperbaric aqueous oxygen (AO, oxygen diluted in saline solution) was infused directly into the PA for 30 min, with continuous reading of the monitored parameters. RESULTS: Hypoxic ventilation raised significantly (P < 0.005) the values of systolic (36+/-7 vs 22+/-6 mmHg), diastolic (16+/-3 vs 9+/-4 mmHg) and mean (24+/-4 vs 14+/-4 mmHg) PA pressure, PA/systemic pressure ratio for systolic (0.47+/-0.09 vs 0.24+/-0.06) and mean (0.49+/-0.13 vs 0.23+/-0.08) pressures and Pulmonary Vascular Resistance (PVR) (6.89+/-0.87 vs 2.67+/-0.38 U), while the Pulmonary Blood Flow (PBF) decreased (2.7+/-0.4 vs 3.7+/-0.4 l/min). AO infusion reduced significantly (P < 0.005) the values obtained with hypoxic ventilation with systolic (26+/-6 vs 36+/-7 mmHg), diastolic (11+/-4 vs 16+/-3 mmHg) and mean (16+/-4 vs 24+/-4 mmHg) PA pressure, PA/systemic pressure ratio for systolic (0.27+/-0.07 vs 0.47+/-0.09) and mean (0.27+/-0.08 vs 0.49+/-0.13) pressures and PVR (3.42+/-0.31 vs 6.89+/-0.87 U), while the PBF increased (3.6+/-0.4 vs 2.7+/-0.4 l/min). CONCLUSIONS: Acute infusion of hyperbaric AO solution into the PA completely reverses the negative effects of acute hypoxia on pulmonary circulation