Surgical management of the severely atherosclerotic ascending aorta during cardiac operations

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.

Intimal aortic atherosclerosis in cardiac surgery: surgical strategies to prevent embolic stroke

 

OBJECTIVES

Although the incidence of perioperative stroke after cardiac surgery gradually decreased over the last decades, there is much variation between centres. This review aimed to create a concise overview of the evidence on possible surgical strategies to prevent embolic stroke in patients with intimal aortic atherosclerosis.

METHODS

The PubMed and EMBASE databases were searched for studies on surgical management of aortic atherosclerosis and the association with perioperative stroke in cardiac surgery, including specific searches on the most common types of surgery. Articles were screened with emphasis on studies comparing multiple strategies and studies reporting on the patients’ severity of aortic atherosclerosis. The main findings were summarized in a figure, with a grade of the corresponding level of evidence.

RESULTS

Regarding embolic stroke risk, aortic atherosclerosis of the tunica intima is most relevant. Although several strategies in general cardiac surgery seem to be beneficial in severe disease, none have conclusively been proven most effective. Off-pump surgery in coronary artery bypass grafting should be preferred with severe atherosclerosis, if the required expertise is present. Although transcatheter aortic valve replacement is used as an alternative to surgery in patients with a porcelain aorta, the risk profile concerning intimal atherosclerosis remains poorly defined.

CONCLUSIONS

A tailored approach that uses the discussed alternative strategies in carefully selected patients is best suited to reduce the risk of perioperative stroke without compromising other outcomes. More research is needed, especially on the perioperative stroke risk in patients with moderate aortic atherosclerosis.

Calcified Homograft With Aortic Insufficiency: A Hybrid Alternative Approach to Clamping

Surgical management of a calcified homograft with associated severe aortic insufficiency is challenging because of the technical difficulty in occluding the aorta. We present a hybrid method of homograft occlusion during the cooling phase of a homograft replacement procedure that required the use of circulatory arrest.

Incidence of postoperative stroke using the Heartstring device in 1,380 coronary artery bypass graft patients with mild to severe atherosclerosis of the ascending aorta

BACKGROUND

Atherosclerotic disease of the ascending aorta during coronary artery bypass graft surgery (CABG) increases the risk for postoperative stroke. The objective of this study was to examine the incidence of postoperative stroke in CABG utilizing the Heartstring (Maquet Cardiovascular, San Jose, CA) proximal anastomotic device.

METHODS

Intraoperative epiaortic ultrasonography was used to grade atherosclerosis in CABG patients at Emory University from April 2003 to December 2012. The Heartstring device was utilized in 1,380 patients: 407 (29.5%) grade I (minimal atherosclerosis), 367 (26.6%) grade II, 437 (31.7%) grade III, 110 (8.0%) grade IV, and 59 (4.3%) grade V (severe atherosclerosis). Logistic regression analysis was used to estimate the effect of aortic grade on outcomes adjusted for Society of Thoracic Surgeons predicted risk of mortality and predicted risk of stroke scores.

RESULTS

The mean age of all patients was 66.7 ± 10.5 years, and 31.9% were female. An increasing risk profile was apparent with rising aortic grade. Most CABG was done off pump (n = 1,277, 92.5%). There was no significant association between aortic grade and frequency of postoperative stroke (p = 0.83). In all patients, use of the Heartstring device reduced the predicted risk of stroke by 44% (O:E risk 0.56). The benefit for postoperative stroke was least apparent in the grade I aorta patients (O:E 0.8) compared with patients having grade II and greater. There were no strokes among patients with severe atherosclerosis using the Heartstring device.

CONCLUSIONS

Compared with the Society of Thoracic Surgeons predicted risk for stroke, the Heartstring proximal anastomotic device can be safely used with all aortic grades. The most prominent benefit appears to be for patients with grade II disease and greater.

The association between atherosclerotic renal artery stenosis and acute kidney injury in patients undergoing cardiac surgery

BACKGROUND

Atherosclerotic renal artery stenosis (ARAS) and coronary artery disease (CAD) commonly co-exist. Some patients with unidentified ARAS may undergo cardiac surgery. While acute kidney injury (AKI) is a frequent and serious complication of cardiac surgery, we aim to evaluate the influence of ARAS on the occurrence of postoperative AKI in patients with normal or near-normal baseline renal function following cardiac surgery.

METHODS

A total of 212 consecutive patients undergoing aortography after coronary angiography and cardiac surgery were retrospectively studied for their preoperative and intraoperative conditions. AKI was defined as an absolute increase in serum creatinine of more than or equal to 0.3 mg/dl (≥26.4 µmol/l) or a percentage increase in creatinine of more than or equal to 50% (1.5-fold from baseline) after cardiac surgery. A propensity score-adjusted logistic regression models was used in estimating the effect of ARAS on the risk of postoperative AKI.

RESULTS

ARAS (≥50%) was observed in 50 (23.6%) patients, and 83 (39.2%) developed AKI after cardiac surgery. A correlation existed between renal artery patency and preoperative-to-postoperative %ΔCr in patients with ARAS (r = 0.297, P<0.0001). The propensity score-adjusted regression model showed the occurrence of postoperative AKI in patients with ARAS was significantly higher than those without ARAS (OR 2.858, 95% CI 1.260-6.480, P = 0.011).

CONCLUSION

ARAS is associated with postoperative AKI in patients with normal or near-normal baseline renal function after cardiac surgery.

Replacement of the ascending aorta for severe atherosclerosis during coronary artery bypass surgery

BACKGROUND AND AIM

In the present study, we investigated the benefit of ascending aorta replacement in patients with severe aortic atherosclerosis who undergo coronary artery bypass surgery (CABG).

METHODS

From January 2001 to April 2011, 3842 patients underwent CABG and in 36 of these patients (31 male, 5 female) the ascending aorta was replaced due to severe atherosclerosis. Total circulatory arrest was used in 22 patients (61%). The patients were followed for 69 ± 36 months (1-133 months) and compared to a control group of patients. The control group consisted of patients who underwent CABG with or without a concomitant procedure (n = 3806).

RESULTS

For the study group, the mean additive and logistic Euroscores of the patients were nine and 20, respectively. One stroke (2.8%) was observed and this patient died in the early postoperative period. There were a total of four confirmed deaths (12%) at any time point over the length of the follow-up among the patients who were discharged from the hospital. Two of them died of malignancy (lung and gastric tumors) and the other two from cardiac reasons. No patients had a stroke during follow-up. For the control group the mean age was 61 ± 1, the stroke rate was 0.6%, and the mortality rate was 0.96%, and the mean logistic and additive Euroscores were 3.7 ± 4.4, and 3.5 ± 2.5, respectively.

CONCLUSIONS

Replacement of highly calcified ascending aortas during CABG can be safely performed in selected patients with good long-term outcomes.

Clampless technique during coronary artery bypass grafting for proximal anastomoses in the hostile aorta

OBJECTIVE

The incidence of stroke in patients undergoing coronary artery bypass grafting increases sharply in the face of significant atherosclerotic disease of the ascending aorta. We use a technique that allows full revascularization for this cohort of patients, while minimizing cerebral embolic risk.

METHODS

Intraoperative epiaortic ultrasound was used to screen for moderate or severe atherosclerotic disease of the ascending aorta and to precisely identify safe areas for cannulation and proximal anastomoses. By using a mildly hypothermic fibrillating technique, distal revascularization was then performed without clamping the aorta. Proximal anastomoses were accomplished under brief periods of circulatory arrest.

RESULTS

We routinely use this technique and examined our results in 71 consecutive patients found to have grade 3 or greater atherosclerotic plaque of the ascending aorta. This represented approximately 10.0% of our total population who underwent coronary artery bypass grafting over a 32-month period from January 2007 to September 2009. One patient (1.4%) had a mild stroke that resolved, and there were no other neurologic complications.

CONCLUSIONS

We have found that clampless fibrillating heart surgery with circulatory arrest for proximal anastomoses is a safe and effective technique for revascularizing patients with significant ascending aortic disease who are at high risk for cerebral embolic complications.

The topography of aortic atherosclerosis enhances its precision as a predictor of stroke

BACKGROUND

Atherosclerosis of the thoracic aorta is an independent risk factor for stroke after cardiac surgery. No attention had so far been paid to its topography. The relationship between the topography of aortic atherosclerosis and stroke was studied in patients admitted for coronary surgery.

METHODS

The extent and location of atherosclerosis in the ascending aorta and arch was assessed intraoperatively with epiaortic ultrasound and transesophageal echocardiography in 611 consecutive patients. They were followed for 5.5 +/- 1.7 years (mean +/- SE), amounting to 3,358 patient-years.

RESULTS

The incidence of early postoperative (<30-day) stroke was 6.4% in patients with atherosclerosis of the ascending aorta and 1.5% in those without (p = 0.004). The five-year stroke-free survival rates (>30 days after the operation) for patients without aortic disease, with less than 50%, and with greater than 50% of the ascending aorta affected, were 95.3 +/- 0.9%, 91.8 +/- 2.1%, and 65.0 +/- 14.6%, respectively (p < 0.0001).

CONCLUSIONS

Atherosclerosis of the ascending aorta stands out as a predictor of late stroke. High risk is predominantly linked to atheromas in its distal part and lesser curvature.

Aortic assessment for cardiac surgical procedures

Aortic atheromatous disease is associated with stroke in both the ambulatory and perioperative setting. In addition to atheromatous deposits, a reduction in the compliance of the aorta takes place as elastin fibers are replaced by collagen fibers. Both of these distinct processes, termed atherosclerosis, can easily be measured using transesophageal echocardiography during cardiac surgery. A review of the literature demonstrates many studies supporting the benefit of transesophageal echocardiography examination of the aorta for reducing stroke following cardiac surgery, through modification of surgical techniques. There have also been attempts by surgeons to remove atheromatous lesions from the aorta during cardiac surgery. Unfortunately, these procedures currently have a high perioperative mortality. Finally, medical therapy such as warfarin or statins may help reduce the incidence of stroke following heart surgery.

Propensity case-matched analysis of off-pump coronary artery bypass grafting in patients with atheromatous aortic disease

OBJECTIVE

Atheromatous aortic disease is a risk factor for excessive mortality and stroke in patients undergoing coronary artery bypass grafting. Outcomes of off-pump coronary artery bypass grafting and coronary artery bypass grafting with cardiopulmonary bypass in patients with severe atheromatous aortic disease were compared by propensity case-match methods.

METHODS

Routine intraoperative transesophageal echocardiography identified 985 patients undergoing isolated coronary artery bypass grafting with severe atheromatous disease in the aortic arch or ascending aorta. Off-pump coronary artery bypass grafting was performed in 281 patients (28.5%). Propensity matched-pairs analysis was used to match patients undergoing off-pump coronary artery bypass grafting (n = 245) with patients undergoing coronary artery bypass grafting with cardiopulmonary bypass.

RESULTS

Univariate analysis revealed decreased hospital mortality (16/245, 6.5% vs 28/245, 11.4%; P =.058) and stroke prevalence (4/245, 1.6% vs 14/245, 5.7%; P =.03) in off-pump coronary artery bypass grafting compared with coronary artery bypass grafting with cardiopulmonary bypass. Freedom from any postoperative complication was higher in off-pump coronary artery bypass grafting compared with coronary artery bypass grafting with cardiopulmonary bypass (226/245, 92.2% vs 196/245, 80.0%; P <.001). Multivariable analysis of preoperative risk factors showed that increased hospital mortality was associated with coronary artery bypass grafting with cardiopulmonary bypass (odds ratio = 2.7; P =.01), fewer grafts (P =.05), acute myocardial infarction (odds ratio = 11.5; P <.001), chronic obstructive pulmonary disease (odds ratio = 2.4; P =.03), previous cardiac surgery (odds ratio = 10.2, P =.05), and peripheral vascular disease (odds ratio = 2.1; P =.05). Cardiopulmonary bypass was the only independent risk factor for stroke (odds ratio = 3.6, P =.03). At 36 months' follow-up, comparable survival was observed in the off-pump coronary artery bypass grafting and coronary artery bypass grafting with cardiopulmonary bypass groups (74% vs 72%). Multivariable analysis revealed that renal disease (P <.001), advanced age (P <.001), previous myocardial infarction (P =.03), and lower number of grafts (P =.02) were independent risks for late mortality.

CONCLUSIONS

Patients with severe atherosclerotic aortic disease who undergo off-pump coronary artery bypass grafting have a significantly lower prevalence of hospital mortality, perioperative stroke, and overall complications than matched patients who underwent coronary artery bypass grafting with cardiopulmonary bypass. Routine intraoperative transesophageal echocardiography identifies severe atheromatous aortic disease and directs the choice of surgical technique.

Current State of Intraoperative Echocardiography

Intraoperative use of echocardiography is becoming more prevalent and is now considered an essential part of modern cardiac surgery. Echocardiography can be performed intraoperatively using transesophageal, epicardial or epiaortic, and substernal approaches. These techniques have a variety of applications in evaluating myocardial and valvular function, assessing aortic atheroma, and determining adequacy of various kinds of repair and reconstruction. Future applications will most likely involve more compact equipment, the implementation of epicardial and transesophageal real-time three-dimensional echocardiography, and better use of provocative methods of intraoperative testing.

Aortic Source of Brain Embolism

Aortic arch atheroma has more recently been identified as an independent risk factor for ischemic stroke. Initially, this was a result of careful autopsy observations, then followed by a series of in vivo studies in which aortic arch atheroma was identified by transesophageal echocardiography. The association of aortic arch atheroma with ischemic stroke is most likely causal, given that the stroke risk increases with increasing thickness of arch atheroma. There is quite a sharp increase in stroke risk for atheroma of 4 mm or greater compared with lesser thicknesses. The clinical diagnosis is suggested when transient ischemic attack or ischemic stroke has occurred in which no obvious cardiac or arterial source of embolism is found. The presence of aortic arch atheroma is usually detected by transesophageal echocardiography and sometimes by magnetic resonance imaging or computed tomography. There is uncertainty about clinical management, particularly for secondary prevention. Options include the use of antiplatelet agents, anticoagulants, thrombolysis, or surgery. The latter two options have only been described rarely in case reports. Of the less invasive approaches, combination antiplatelet therapy with aspirin and clopidogrel is favored, or the use of warfarin. The Aortic arch Related Cerebral Hazard (ARCH) trial is being conducted to determine which of these is more effective in minimizing a composite outcome cluster of ischemic stroke, intracranial hemorrhage, myocardial infarction, peripheral embolism, or vascular death. Other more general management strategies should include reasonably aggressive risk factor control with blood pressure and lipid-lowering therapies and, if indicated, careful diabetic control.

Complete Myocardial Revascularization in Severe Arteriopathy

Multivessel coronary revascularization was successfully performed in a 75-year-old man with severe atherosclerosis of the ascending aorta and aortic arch, significant stenoses in the right subclavian, innominate, and aortoiliac arteries, renal impairment, and conduit shortage, by combining the beating-heart approach with aorta-sparing pedicled arterial and venous grafts. No postoperative complications were encountered.

Isolation technique for stroke prevention in patients with a mobile atheroma

Mobile atheroma in the proximal aorta is a risk factor for brain complication after cardiovascular operation. We report a new technique of replacing the ascending and transverse aorta by establishing selective hypothermic antegrade cerebral perfusion. After cooling, cerebral vessels are clamped and systemic perfusion is started. This technique was applied in 5 patients. All patients woke up normally and recovered without neurologic complication.

Postoperative stroke in cardiac surgery is related to the location and extent of atherosclerotic disease in the ascending aorta

OBJECTIVES

The aim of the study was to evaluate the risk from calcified atheromas in the ascending aorta, and the extent and topography of the disease in the development of stroke after cardiac surgery.

BACKGROUND

Postoperative stroke constitutes a serious problem in cardiac surgery, and atherosclerosis of the ascending aorta is an important risk factor.

METHODS

Before surgical manipulation epiaortic echocardiographic ultrasound was performed to evaluate the ascending aorta in 921 consecutive patients undergoing cardiac surgery. The presence of calcification, location of atheroma, extent of the disease and clinical variables including postoperative stroke were recorded prospectively.

RESULTS

A total of 26.2% of the patients had atherosclerosis of the ascending aorta, and in 44.4% of them more than one of 12 possible segments was involved. Logistic regression showed that atherosclerotic disease in the ascending aorta was the most important predictive factor for postoperative stroke. The incidence of stroke was 1.8% in patients without atherosclerotic disease of the ascending aorta, and 8.7% in patients with the disease (p < 0.0001). Diabetes mellitus was also a predictive factor (p = 0.04). A new and unique finding of this study was that the middle-lateral segment is an independent predictive factor for postoperative stroke, with a relative risk of 26% (p = 0.04).

CONCLUSIONS

Patients with atheromatosis in the ascending aorta had an 8.7% incidence of postoperative stroke, in spite of minor surgical modifications. The risk depended on the presence, location and extent of the disease. Randomized trials evaluating alternative surgical strategies in coronary surgery are urgently needed in high risk patients.

Surgical techniques. Ascending aorta

Aneurysm and dissection are the most common diseases affecting the ascending aorta. Graft replacement of the ascending aorta is a straightforward cardiovascular procedure with excellent early and late results. When aneurysm or dissection extends into the aortic sinuses or arch, management becomes more complex and may entail replacement of the aortic root, aortic valve, or a portion of the aortic arch using hypothermic circulatory arrest. The optimal root prosthesis depends on several patient- and procedure-related variables. Valve-sparing procedures confer many long-term advantages and should be considered in all cases where the aortic valve leaflets are normal. The Ross procedure, although ideally suited for isolated aortic valve disease in young patients, may be applicable to some patients with combined aortic valve and ascending aortic disease, unless there is evidence of a systemic connective tissue disorder.