Nine female pigs, 5 to 6 months old, weighing between 50 and 55 kg were studied to explore the feasibility of superficial femoral artery (SFA), access for coronary angiography and provisional PCI. Additionally, we sought to explore the most appropriate guiding coronary catheters and angiographic projections for the above procedures.
All animals were kept in individual cages, in air-conditioned rooms and given a minimum of 24 h to recover from the stress of transport before the first procedure. Food was withheld for 12 h before anesthesia.
All procedures performed complied with the Declaration of Helsinki regarding the ethical principles of medical research and were approved by the Animal Care and Use Council of the Ethics Committee of Patras University Hospital and the Council veterinarian of the provincial authorities of Western Greece. In addition, the protocol complied with the ARRIVE guidelines.
Anesthesia and intubation
All animal experiments were performed under general anesthesia according to established anesthetic protocols14.15 with a combination of 15 mg/kg of intramuscular ketamine (Ketamidor®Richter Pharma, Wels, Austria) and 2 mg/kg xylazine (Xylan®, Chanelle Pharmaceuticals, Loughrea, Ireland), followed by endotracheal intubation. This approach has been shown to reduce ventricular arrhythmias6. The intubation process has been described in both supine and prone positions with the use of a long, straight-bladed Magill laryngoscope.6.
In our case, the pigs were intubated in the supine position (Fig. 1), using either a standard laryngoscope or a long straight blade Magill laryngoscope when deemed necessary, depending on the length of the oral cavity. and pharynx. An assistant held the pig’s mouth open while applying traction to the tongue. Once the vocal cords were visualized, a standard lubricated 7 mm human endotracheal tube was inserted using a candle. In addition, a 20-gauge intravenous catheter was inserted into the lateral ear vein. Both were held in place with 2–0 nylon polyamide sutures.
Gas-maintained anesthesia is generally advised for such procedures with isoflurane or sevoflurane being considered the agents of choice10,14,15. Our procedures were performed by continuous infusion of propofol at a rate of 1 to 1.4 mg/kg, which was associated with maintenance of sinus rhythm and protection of atrioventricular node function without prolonging ventricular refractory.16.
We used a RAPHAEL color ventilator (Hamilton Medical, Bonaduz, Switzerland) to apply synchronized controlled mandatory ventilation with minute ventilation of 6.4 L/min at 14 breaths/min and an exhaled tidal volume of 462 ml. Pulse oximetry and heart rate were monitored throughout the operation.
SFA was chosen for arterial access. The puncture site was cleaned with povidone iodine solution and then draped sterile.
An ultrasound machine (Logiq E9—General Electric®, Chicago, USA) equipped with a 4–15 MHz transducer (ML6-15-D Matrix Linear Probe) was used to guide the puncture (Fig. 2). The Seldinger technique with a 21-gauge needle was used to access the right-sided SFA17. After recognition of the SFA by real-time ultrasound, the needle was inserted at 60–80 degrees to the artery and when the pulsating blood returned, a 0.035″ wire (Boston Scientific®, Marlborough, USA) was introduced (Fig. 3a,b). The needle was replaced with a 6-Fr-10 cm radial artery sheath (Terumo Medical Corporation®, Shibuya, Japan). Once arterial access was obtained, 100 U/kg of heparin was administered to achieve systemic anticoagulation. Intra-arterial blood pressure and arterial saturation via a pulse oximeter mounted on the animal’s tail were monitored throughout the procedure. The entire procedure was performed by three experienced operators.
Our anecdotal experience prior to the current experimental study has shown that for porcine models of similar age and size, the Amplatzer AR1® (medical cook®Bloomington, USA) and right coronary artery bypass surgery® (RCB) catheter (Cordis Corporation®Hialeah, USA), may be best suited for selective right and left coronary artery engagement, respectively (Table 1).
Angiographic Views and Coronary Angiography Procedure
Due to differences in heart orientation, modifications to the standard angiographic views used in humans may be necessary in order to optimize visualization of the coronary arterial system in porcine models. Identifying the most appropriate angiographic views has also been the goal of the ongoing feasibility study.
All procedures were performed using the same angiography system (Allura Flat Panel®Phillips®, Amsterdam, Netherlands). The left anterior oblique (LAO) view was found to be optimal for depicting the right coronary artery and a posteroanterior cranial view for the left coronary artery (Fig. 4a,b).
Hemostasis and recovery
After the procedure was completed, hemostasis was achieved using an arterial closure device (ANGIO-SEAL® VIP Vascular Closure Device, Terumo Interventional Systems®Shibuya, Japan) and patency of the femoral artery was confirmed by Doppler ultrasound (Fig. 5).
Follow-up and euthanasia
Thirty days after the initial procedure, a reoperation using ultrasound-guided transfemoral access was performed in the unilateral SFA. All steps described previously were followed and the same guiding catheters were used for coronary angiography.
Once the protocol was completed, the animals were transferred to the recovery room and euthanasia was performed.
All applicable international, national and/or institutional guidelines for animal care and use were followed.