Cardiac surgery in patients with a porcelain aorta in the era of transcatheter valve implantation

Surgical strategies for severely atherosclerotic (porcelain) aorta during coronary artery bypass grafting

Porcelain aorta (PA) is an asymptomatic atherosclerotic disease, characterized by circumferential calcification throughout the whole perimeter of the aorta. It is seen in 2% to 9.3% of patients undergoing elective coronary artery bypass grafting (CABG) and makes manipulation of the ascending aorta impossible. It has been clearly shown that most emboli seen and detected during the CABG procedure occur during aortic cross-clamping and aortic side-clamping. Manipulation of porcelain or a severely atherosclerotic aorta increases the risk of perioperative stroke. The incidence of stroke after CABG is between 0.48% and 2.9%, and the risk is correlated with the extent and severity of the atherosclerotic disease. A conventional CABG procedure involves successive steps that include cannulation of the ascending aorta, application of a cross-clamp to the aorta, and partial clamping of the aorta to create the proximal anastomosis. Therefore in procedures that involve cannulation, clamping, or proximal anastomosis, and where aortic manipulation is inevitable, preassessment of the atherosclerotic aortic plaques is crucial. Although many surgeons still rely on intraoperative manual aortic palpation, this approach has very low sensitivity and underestimates the severity of the atherosclerotic illness. Imaging methods including preoperative computed tomography or intraoperative epiaortic ultrasonography enable modification of the surgical technique according to the severity of atherosclerosis. Various surgical techniques have been described to reduce the risk of atheroembolism that may lead to cerebrovascular events in patients with severely atherosclerotic ascending aorta. Anaortic or "no-touch" techniques that do not utilize aortic manipulation may significantly decrease the development of neurological complications by avoiding aortic maneuvers known to cause emboli. In cases where severe atherosclerotic disease or other factors preclude safe use of the ascending aorta, modifications in the surgical techniques, such as switching to different cannulation sites including the axillary/subclavian, femoral and innominate arteries, or using hypothermic ventricular fibrillation and in-situ pedicled arterial grafts, or performing proximal anastomoses at alternative anatomical locations will enable CABG operations to be performed safely with low morbidity and mortality rates in patients with porcelain aortas.

The Role of Deep Hypothermia in Cardiac Surgery

Hypothermia is defined as a decrease in body core temperature to below 35 °C. In cardiac surgery, four stages of hypothermia are distinguished: mild, moderate, deep, and profound. The organ protection offered by deep hypothermia (DH) enables safe circulatory arrest as a prerequisite to carrying out cardiac surgical intervention. In adult cardiac surgery, DH is mainly used in aortic arch surgery, surgical treatment of pulmonary embolism, and acute type-A aortic dissection interventions. In surgery treating congenital defects, DH is used to assist aortic arch reconstructions, hypoplastic left heart syndrome interventions, and for multi-stage treatment of infants with a single heart ventricle during the neonatal period. However, it should be noted that a safe duration of circulatory arrest in DH for the central nervous system is 30 to 40 min at most and should not be exceeded to prevent severe neurological adverse events. Personalized therapy for the patient and adequate blood temperature monitoring, glycemia, hematocrit, pH, and cerebral oxygenation is a prerequisite and indispensable part of DH.

Plaster pipes and crystalized graphite: Open transventricular transcatheter aortic valve replacement for failed mechanical aortic valve prostheses in the porcelain aorta

Patients with a true porcelain aorta and a failed mechanical aortic valve prosthesis have limited treatment options. Using a hybrid of an open trans-ventricular approach with peripheral cardiopulmonary bypass and integration of transcatheter techniques this challenge can be overcome. Trans-ventricular mechanical valve extraction (with transcatheter endovascular occlusion and cardioplegia) followed by direct ante-grade transcatheter heart valve implantation offers a potential solution to this conundrum. The procedure described is a novel technique that allows for the effective treatment of patients with failed mechanical surgical aortic valve prostheses in the setting of an inoperable porcelain aorta. In addition, a collaborative integrated multi-disciplinary heart team environment is required for the management of these complex patients.

Effectiveness and Safety of Transcatheter Aortic Valve Implantation for Aortic Stenosis in Patients With "Porcelain" Aorta

Surgical aortic valve replacement (SAVR) in patients with porcelain aorta is considered a high-risk procedure. Hence, transcatheter aortic valve implantation (TAVI) is emerging as the intervention of choice. However, there is a paucity of data directly comparing TAVI with SAVR in patients with porcelain aorta. We compared outcomes of TAVI versus SAVR in high-risk patients with porcelain between March 2012 and June 2015. The TAVI group included 54 patients, whereas 130 SAVR patients with porcelain aorta were identified (operated on between 2004 and 2015). Both groups were matched 1:1 based on the Society of Thoracic Surgeons Predicted Risk of Mortality (STS-PROM) score with a 0.5% a priori caliper, resulting in 52 matched pairs. The mean STS-PROM was 7.3 ± 3.9 for both groups (p = 0.98), whereas mean age was 77.5 years for TAVI and 78.8 years for SAVR (p = 0.46). Compared with SAVR, TAVI patients had lower operative mortality (3.8% vs 17.3%; p = 0.052), significantly shorter median intensive care unit (40 vs 107 hours; p < 0.001) and hospital (5 vs. 7 days; p < 0.001) length of stay (LOS), but similar postoperative stroke rates (7.7% vs 11.5%; p = 0.74). One-year unadjusted survival was 81.7% (95% confidence interval [CI]: 69.8% to 93.5%) in the TAVI group versus 71.2% (95% CI: 61.0% to 85.1%) in the SAVR group, p = 0.093. Cox proportional hazard modeling identified preoperative chronic kidney disease (hazard ratio: 2.63 [95% CI: 1.03 to 6.70]; p = 0.043) and SAVR (hazard ratio: 2.641 [95% CI: 1.07 to 6.51]; p = 0.035) as significant predictors for decreased survival. Overall, TAVI was associated with reduced operative mortality, increased survival, and shorter intensive care unit and hospital length of stay compared with SAVR in patients with porcelain aorta. This study demonstrates that TAVI is a safe intervention in this high-risk population.

Carotid artery cannulation in aortic surgery

The common carotid artery is not widely used for arterial return in cardiovascular surgery with the use of extracorporeal circulation; however, in our opinion, it is an artery that most ideally fits several criteria for cannulation use. It is easy and very fast to access, even in obese patients, and it is large and strong enough to provide a sufficient arterial return. Moreover, the risk of local injuries and wound infection is extremely low, and finally, the use of the common carotid artery for cannulation is very advantageous for cerebral perfusion in many pathologies of the aortic arch and its branches.

Assessing the risk of aortic valve replacement for severe aortic stenosis in the transcatheter valve era

Surgical aortic valve replacement had been the only definitive treatment of severe aortic stenosis before the availability of transcatheter valve technology. Historically, many patients with severe aortic stenosis had not been offered surgery, largely related to professional and patient perception regarding the risks of operation relative to anticipated benefits. Such patients have been labeled as "high risk" or "inoperable" with respect to their suitability for surgery. The availability of transcatheter aortic valve replacement affords a new treatment option for patients previously not felt to be optimal candidates for surgical valve replacement and allows for the opportunity to reexamine the methods for assessing operative risk in the context of more than 1 available treatment. Standardized risk assessment can be challenging because of both the imprecision of current risk scoring methods and the variability in ascertaining risk related to operator experience as well as local factors and practice patterns at treating facilities. Operative risk in actuality is not an absolute but represents a spectrum from very low to extreme, and the conventional labels of high risk and inoperable are incomplete with respect to their utility in clinical decision making. Moving forward, the emphasis should be on developing an individual assessment that takes into account procedure risk as well as long-term outcomes evaluated in a multidisciplinary fashion, and incorporating patient preferences and goals in a model of shared decision making.

Bad aorta

As its outcomes improve, cardiac surgery has been performed on more and more cases which were previously considered to be difficult to deal with. However, there are still a number of problems to be solved regarding surgery on patients with severe sclerotic lesions in the ascending aorta, which we collectively call "bad aorta". Concerning a preoperative assessment of the ascending aorta, our report revealed no relationship between the severity of calcification detected with a preoperative non-enhanced CT and the aortic lesion found during the surgery. Meanwhile, an intraoperative epiaortic ultrasound enables us to make high-quality evaluations of the aorta without imposing much burden on the patient. This modality may be essential for cardiac surgery. As for surgical management for bad aorta, quite a few methods have been reported to this point, but the overall operative mortality rate and cerebrovascular accident rate are relatively high, at a little <10 %, respectively. With the recent cross-clamping method under short-term total circulatory arrest (TCA), however, the results are much better; these rates total around 5 %. Further improvement is expected in the outcome of cardiac surgery on bad aorta cases by establishing a modality to evaluate sclerotic lesions in the ascending aorta with epiaortic ultrasound and by selecting a proper procedure for each case.