Significant differences exist among the described strategies for coronary catheterization of porcine models.6,8 However, a relatively high mortality rate (up to 15%), has been reported in the literature in healthy porcine models during or following coronary intervention.6 This may in part be due to the techniques used and/or their application be relatively inexperienced operators.6 We describe a feasible and reproducible experimental protocol for coronary angiography and provisional interventions in porcine models using an ultrasound-guided femoral access and specific guiding-catheters (AR1 and RCB).
Femoral and carotid arteries have all been proposed and studied for percutaneous arterial access in swines.9,13,18−20 Until recently, the femoral artery was used as an access route via a surgical cut-down and sheath insertion using an arteriotomy or modified Seldinger technique.
Ultrasound guidance has been used successfully in humans for arterial access, and it has been associated with less complications, punctures and procedural time.21
Vascular ultrasound has been applied in porcine models mainly for the carotid arterial access, and has also been tested for percutaneous needle puncture of the femoral artery for application of extracorporeal membrane oxygenation and for minimally invasive catheterization of the external jugular vein.9,12,13,22 Recently, ultrasound guidance has been shown to facilitate femoral arterial access and reduce vascular complications in porcine models.13,14 However, ultrasound guided femoral artery access for coronary catheterization in porcines, has not been studied extensively. According to our results the ultrasound-guided femoral artery approach was feasible, quick, easy-to-learn and safe, without causing any significant complications. Additionally, the puncture of the same femoral artery, after one month, was proven feasible and did not reveal any complications (i.e. stenosis, or obstruction) associated with the use of the vascular closure device, thus proving our proposing approach to be reproducible.
Overall, we recommend this approach as first-line choice for gaining arterial access in porcine models subjected to coronary angiography and interventions.
Despite the fact that similarities between humans’ and porcines’ heart exist, there are differences regarding the shape of the heart and its orientation in the thorax. The human heart has a trapezoidal shape, whilst the porcines’ heart, has a cone-shaped form. Additionally, the porcine heart has a rather central orientation in the thorax.23 Therefore, classic catheter shapes, designed for coronary angiography and interventions for human patients, may fail to engage selectively the porcines’ coronary arteries. As a result, there is not any established and reproducible protocol regarding the most suitable guide catheters for experimental coronary procedure in porcines.
According to the literature, angiographic catheters used to engage the porcine coronary ostia may vary according to the arterial access used. Amplatz right and left as well as JR4 and hockey stick catheters have been used to engage both coronary arteries with the carotid artery approach.3 JR4 was proven more suitable for the RCA while others like the standard extra backup and JL3.5 or JL4 catheters can also be useful for the LCA.6 AR1 or hockey stick catheters can be used to engage both coronaries and JL3.5 and AL0.75 can be used to engage the LCA in the femoral approach.3,6,10
We found that the AR1 catheter was the best choice for the right coronary system while the RCB was best suited for the left, both allowing easy and quick selective catheterization with a 100% success rate.
The coronary tree of porcines resembles that of humans, with vessels having a similar diameter, between 2 and 4 mm.3 The ideal projections for each coronary artery should ensure a good imaging quality, the avoidance of arterial overlapping and the ability to overview the status of the whole coronary artery with its branches. The AP and left anterior oblique (LAO) views have been described as suitable for the depiction of proximal LAD, with Cx being to the left and to the right of the guide catheter tip respectively. An AP view as well as the RAO and LAO are useful for the RCA.6 According to our experience, the AP cranial and the RAO cranial view is best suited for the left coronary system, whereas the LAO for the RCA.
During our protocol, only one animal suffered a transient spasm of the RCA, but that was quickly resolved with intraarterial nitrates.