Discussion:
In patients with a porcelain ascending aorta, cardiac surgery is challenging. The manipulation of the thoracic aorta during cardiac surgery, such as cross-clamping, incisions or cannulations, increases the risk of perioperative embolic stroke in these patients(3) and more importantly damage or incisions to porcelain aorta are not repairable and can risk patients live on table. As an alternative to hypothermic fibrillatory arrest, deep hypothermic total circulatory arrest techniques are most commonly used for mitral valve surgery(4). As an alternative to conventional mitral valve surgery, beating heart mitral valve surgery without cross-clamping the aorta has been successfully performed with acceptable clinical outcomes(5-7).
Arterial perfusion via the common femoral artery is a classic approach to cardiac surgery in patients with calcification of the ascending aorta. In spite of its ease of use, this method carries the risk of embolization by atherosclerotic plaque or thrombus from the thoracic and abdominal aortas due to retrograde perfusion(8). However, Grossi et al (9). demonstrated that retrograde perfusion had no significant impact on stroke incidence in patients <50 years of age, (as in our patient 40 year old with low risk of atherosclerosis) but had a significant effect on neurological events in high-risk patients with aortic disease. Nevertheless, several reports have described positive results of axillary artery cannulation, which has become increasingly popular(10-12).
Axillary artery perfusion is associated with a lower risk of cerebral atheroembolism because it is less affected by atherosclerosis than the femoral artery. It can be used for selective antegrade cerebral perfusion to avoid cannulation in patients with severe atheroma of the brachiocephalic artery. The axillary vessels also have abundant collaterals, which reduces the risk of severe distal ischemia-reperfusion injury or embolization following cannulation(13).
Patients with severe porcelain aortas may benefit from cannulation of the brachiocephalic artery. It is possible to avoid the difficulties associated with a second incision (axillary artery cannulation) or the problems associated with retrograde perfusion (femoral artery cannulation) by utilizing the brachiocephalic artery(14). Transapical aortic cannulation is an alternative method of central cannulation but its clinical impact in patients with porcelain aorta is unclear(15).
One of the most feared complications of mitral valve replacement in a beating heart is air embolism. A patient’s position (head down), strict application of routine de-airing maneuvers, intraoperative use of transesophageal echocardiography for the detection of bubbles, and a competent aortic valve reduce the risk of air embolism(16).
Conclusion: It is critical to diagnose patients with porcelain aorta preoperatively so that appropriate surgical methods can be prepared. Furthermore, peripheral arteries assessment is mandatory to select excellent site for cannulation. Although severe calcification of the ascending aorta can easily be detected on a chest X-ray film or by cine angiography, these modalities are not able to determine whether there is nearly or completely circumferential calcification. It is possible to demonstrate calcification in the aorta with a simple chest CT, but it does not provide a satisfactory assessment of the three-dimensional distribution of calcification. Furthermore, multidetector-row CT images with maximum intensity projections and volume-rendered images can be used to evaluate calcification in three dimensions A beating heart mitral valve surgery without aortic cross clamp can be performed safely as long as all precautions are taken to prevent the most feared complication: an air embolism and adequate arterial cannulation.