Surgical management of the atherosclerotic ascending aorta: is endoaortic balloon occlusion safe?

The Rationalisation of Intra-Operative Imaging During Cardiac Surgery: A Systematic Review

INTRODUCTION

One critical complication of cardiac surgery is cerebrovascular accidents (CVAs). Ascending aorta atherosclerosis poses a significant risk of embolisation to distal vessels and to cerebral arteries. Epi-aortic ultrasonography (EUS) is thought to offer a safe, high-quality accurate visualisation of the diseased aorta to guide the surgeon on the best surgical approach to the planned procedure and potentially improve neurological outcomes post-cardiac surgery.

METHOD

The authors conducted a comprehensive search of PubMed, Scopus and Embase. Studies that reported on epi-aortic ultrasound use in cardiac surgery were included. Major exclusion criteria were: (1) abstracts, conference presentations, editorials, literature reviews; (2) case series with <5 participants; (3) epi-aortic ultrasound in trauma or other surgeries.

RESULTS

A total of 59 studies and 48,255 patients were included in this review. Out of the studies that reported patient co-morbidities prior to cardiac surgery, 31.6% had diabetes, 59.5% had hyperlipidaemia and 66.1% had a diagnosis of hypertension. Of those that reported significant ascending aorta atherosclerosis found on EUS, this ranged from 8.3% of patients to 95.2% with a mean percentage of 37.8%. Hospital mortality ranged from 7% to 13%; four studies reported zero deaths. Long-term mortality and stroke rate varied significantly with hospital duration.

CONCLUSION

Current data have shown EUS to have superiority over manual palpation and transoesophageal echocardiography in the prevention of CVAs following cardiac surgery. Yet, EUS has not been implemented as a routine standard of care. Extensive adoption of EUS in clinical practice is warranted to aid large, randomised trials before making prospective conclusions on the efficacy of this screening method.

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.

Aortic valve replacement in porcelain aorta-a novel technique for endoaortic occlusion

Aortic valve surgery invariably becomes a high-risk, challenging procedure when there is extensive calcification of the ascending aorta which precludes safe cross-clamping. Very few case reports of performing aortic valve surgery in this condition with a non-cross-clamping technique of using endoaortic occlusion have been reported. We describe and recommend a non-cross-clamping technique of using a semi-compliant polyurethane balloon catheter (CODA balloon, Cook Incorporated, Bloomington, IN) and report its successful outcome in a patient, with porcelain aorta, who underwent aortic valve replacement.

Robotic Mitral Valve Repair

Objective

Adoption of robotic mitral valve surgery has been slow, likely in part because of its perceived technical complexity and a poorly understood learning curve. We sought to correlate changes in technical performance and outcome with surgeon experience in the “learning curve” part of our series.

Methods

From 2006 to 2011, two surgeons undertook robotically assisted mitral valve repair in 458 patients (intent-to-treat); 404 procedures were completed entirely robotically (as-treated). Learning curves were constructed by modeling surgical sequence number semiparametrically with flexible penalized spline smoothing best-fit curves.

Results

Operative efficiency, reflecting technical performance, improved for (1) operating room time for case 1 to cases 200 (early experience) and 400 (later experience), from 414 to 364 to 321 minutes (12% and 22% decrease, respectively), (2) cardiopulmonary bypass time, from 148 to 102 to 91 minutes (31% and 39% decrease), and (3) myocardial ischemic time, from 119 to 75 to 68 minutes (37% and 43% decrease). Composite postoperative complications, reflecting safety, decreased from 17% to 6% to 2% (63% and 85% decrease). Intensive care unit stay decreased from 32 to 28 to 24 hours (13% and 25% decrease). Postoperative stay fell from 5.2 to 4.5 to 3.8 days (13% and 27% decrease). There were no in-hospital deaths. Predischarge mitral regurgitation of less than 2+, reflecting effectiveness, was achieved in 395 (97.8%), without correlation to experience; return-to-work times did not change substantially with experience.

Conclusions

Technical efficiency of robotic mitral valve repair improves with experience and permits its safe and effective conduct.

Computational evaluation of aortic occlusion and the proposal of a novel, improved occluder: Constrained endo-aortic balloon occlusion

Because aortic occlusion is arguably one of the most dangerous aortic manipulation maneuvers during cardiac surgery in terms of perioperative ischemic neurological injury, the purpose of this investigation is to assess the structural mechanical impact resulting from the use of existing and newly proposed occluders. Existing (clinically used) occluders considered include different cross-clamps (CCs) and endo-aortic balloon occlusion (EABO). A novel occluder is also introduced, namely, constrained EABO (CEABO), which consists of applying a constrainer externally around the aorta when performing EABO. Computational solid mechanics are employed to investigate each occluder according to a comprehensive list of functional requirements. The potential of a state of occlusion is also considered for the first time. Three different constrainer designs are evaluated for CEABO. Although the CCs were responsible for the highest strains, largest deformation, and most inefficient increase of the occlusion potential, it remains the most stable, simplest, and cheapest occluder. The different CC hinge geometries resulted in poorer performance of CC used for minimally invasive procedures than conventional ones. CEABO with a profiled constrainer successfully addresses the EABO shortcomings of safety, stability, and positioning accuracy, while maintaining its complexities of operation (disadvantage) and yielding additional functionalities (advantage). Moreover, CEABO is able to achieve the previously unattainable potential to provide a clinically determinable state of occlusion. CEABO offers an attractive alternative to the shortcomings of existing occluders, with its design rooted in achieving the highest patient safety. Copyright © 2016 John Wiley & Sons, Ltd.

Clinical Safety and Effectiveness of Endoaortic as Compared to Transthoracic Clamp for Small Thoracotomy Mitral Valve Surgery: Meta-Analysis of Observational Studies

Controversies remain on the increased rate of neurological events after small thoracotomy mitral valve surgery attributed to endoaortic balloon occlusion (EABO). Systematic literature search of databases identified 17 studies enrolling 6,643 patients comparing safety and effectiveness of EABO versus transthoracic clamp. In a meta-analysis, there was no difference in occurrence of cerebrovascular events, all-cause mortality, and kidney injury. EABO was associated with a significantly higher risk of iatrogenic aortic dissection (0.93% versus 0.13%; risk ratio, 4.67; 95% confidence interval, 1.62 to 13.49; p = 0.004) and a trend toward longer operative times. The data is limited to observational studies.

DESIGN, FABRICATION, AND TEST OF A NOVEL CLAMPER FOR AORTIC CROSS-CLAMPING IN MINIMALLY INVASIVE CARDIAC SURGERY

One of the main procedures in the most minimally invasive cardiothoracic surgery is clamping the ascending aorta to disconnect the heart from circulation. In this paper, a new aortic clamping instrument which is applicable in minimally invasive cardiac surgery has been presented. The instrument consists of a parallelogram mechanism for opening and closing the jaws, a detachable holder with a two degree of freedom joint that makes the precise position and orientation of the jaws and leaves the clamping component in the patient’s body to make the inserting port free, and a handle for easy manipulation. In vitro test has been performed to evaluate the performance of the clamper compared to the conventional clampers. For this purpose, the force required for aortic cross-clamping and the maximum aortic displacement have been studied in four groups including parallel clamper and conventional clamper with angles of 1[Formula: see text], 2[Formula: see text], and 3[Formula: see text] between jaws, with 10 bovine aorta specimens in each group. These experiments show that the amount of required force for cross-clamping by using the parallel clamper, is statistically significant ([Formula: see text]) compared with the conventional clampers. Also, the increase of angle between jaws makes a significant increase in the percentage of aortic displacement.

Design and finite element analysis of a novel smart clamper for aortic cross-clamping in minimally invasive surgery

Aortic cross-clamping is a critical action during heart surgeries which may cause some injuries to the wall of the artery. These injuries may have both short-term and long-term adverse effects on the artery function. Appropriate clampers can properly occlude the artery and decrease the extent of injury. Thus, developing a model for evaluation of such clampers is inevitable. In this paper, a finite element model of the aorta is presented; then, different mechanisms of clamping are investigated. In this regard, a numerical model of aortic cross-clamping by three types of clampers has been implemented with consideration of nonlinear behavior of two-layer artery, residual stress in aorta, and calcification. These three clamper models are commercial Chitwood clamper and linear mechanism clamper with and without balloon. Using the obtained results, comparative analysis was performed between the proposed clamper design and the commercial one. Based upon the analysis, it was concluded that the designed clamper, linear mechanism clamper with balloon, helps to distribute the stress uniformly in different layers of the aorta, which results in better performance of the clamping procedure and causes less injury in the aorta, especially when there is calcification.

Long-Term Follow-Up of Minimally Invasive Cardiac Surgery Using an Endoaortic Occlusion System

<p><b>Objectives:</b> We reviewed the initial patient series (n=116) of our institution performing minimally invasive coronary artery bypass grafting (CABG) (n=79), mitral valve surgery (n=1), or atrial septal closure (ASD) procedures (n=26) using an endoaortic occlusion system. With this technique relevant intra-aortic pressures are exerted on the aortic wall during the clamping time. This might lead to late aortic degeneration and aneurysm formation. Our study sought to evaluate postoperative aortic complications and the quality of life (modified SF-12).</p><p><b>Methods:</b> One hundred sixteen patients (56% male; 54 years � 14.5; range 19 years to 77 years) underwent a cardiac procedure using an endoaortic clamp. The endoaortic balloon clamp catheter was used to occlude the ascending aorta at pressures >300 mmHg. Patients were rescheduled for echocardiographic examination after a mean follow-up period of 8.8 years.</p><p><b>Results:</b> The analysis performed among 78 patients showed no incidence of any structural damage to the ascending aorta at the intraoperative position of the endoaortic balloon. The physical and mental summary scores are equal to those of comparable patient groups.</p><p><b>Conclusions:</b> The endoaortic occlusion system causes no damage to the aortic wall. If the system causes any problems, they occur immediately during surgery. Patients treated with this minimally invasive technique exhibited the same quality of life as those undergoing conventional surgery.</p>

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.

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

OBJECTIVES

New surgical and perfusion techniques allow the avoidance of deep hypothermia during open aortic arch surgery, which is generally necessary in patients with an unclampable porcelain aorta. The aim of the study was to evaluate operative and long-term results in patients with a porcelain aorta who underwent conventional cardiac surgery using current surgical and perfusion techniques.

METHODS

Between November 2003 and February 2012, 30 consecutive patients (mean age 68 ± 11 years, 10 patients had previous cardiac surgery with use of glue in 5 of them) with porcelain aorta diagnosed by computed tomography and defined as a severe circular calcification of the proximal thoracic aorta were referred for cardiac surgery. All patients underwent conventional surgery with arterial cannulation of the innominate (8) or a carotid artery (22) for arterial return. During mild hypothermic circulatory arrest, unilateral cerebral perfusion through the arterial line was performed for cerebral protection. The valve surgery consisted of aortic, mitral or double valve repair in 23, 3 and 4 cases, respectively. Aortic surgery (17 complete root replacements with valve composite grafts and 22 arch replacements) and coronary revascularization due to coronary heart disease (15) were the most frequent concomitant procedures.

RESULTS

Thirty-day mortality was 3.3% (1 patient died of bowel ischaemia caused by severe stenosis of the celiac and upper mesenteric arteries) and the rate of permanent neurological deficit was 3.3% as well. Two further patients died during the follow-up at age 91 and 82 years, respectively; however, no death was cardiac or valve related. The actuarial survival at 5 years was 87.3 ± 7.2%. There were no cardiac reoperations, new interventions or aortic- or valve-related events noted during the median follow-up of 45 months (range 0.1-106.0).

CONCLUSIONS

Conventional cardiac and aortic surgery offers definitive repair and can be performed safely using current perfusion and operative techniques. Although more invasive, this surgical technique provides mortality and morbidity rates that do not exceed those reported for transcatheter valve implantation. The curative replacement of the pathological proximal aorta, which is one of the most main sources of cerebral embolism, leads to excellent neurological outcome during mid- to long-term follow-up.

Surgical experience of ascending aorta and aortic valve replacement in patient with calcified aorta

Background

The conventional method of aortic cross-clamping is very difficult and increases the risk of cerebral infarct due to embolism of the calcified aorta in these patients. Accordingly, we analyzed our experience with 11 cases of ascending aorta and aortic valve replacement with hypothermic circulatory arrest.

Materials and Methods

From January 2002 to December 2009, 11 patients had ascending aorta and aortic valve replacement with hypothermic arrest at our hospital. We performed a retrospective study.

Results

There were 5 males and 6 females, with a mean age of 68 years (range, 44 to 82 years). Eight patients had aortic stenosis, and 3 patients had aortic regurgitation. An aortic cannula was inserted into the right axillary artery in 3 patients and ascending aorta in 6 patients. Two patients with aortic regurgitation had a remote access perfusion catheter inserted though the right femoral artery. The mean cardiopulmonary bypass time was 180 minutes (range, 110 to 306 minutes) and mean hypothermic circulatory arrest time was 30 minutes (range, 20 to 48 minutes). The mean rectal temperature during hypothermic circulatory arrest was 21℃ (range, 19℃ to 23℃). No patient had any new onset of cerebral infarct or cardiovascular accident after surgery. There was no hospital mortality. Early complications occurred in 1 patient who needed reoperation due to postoperative bleeding. Late complications occurred in 1 patient who underwent a Bentall operation due to prosthetic valve endocarditis. The mean follow-up duration was 32 months (range, 1 month to 8 years) and 1 patient died suddenly due to unknown causes after 5 years.

Conclusion

Patients with a calcified aorta can be safely treated with a technique based on aorta and aortic valve replacement under hypothermic circulatory arrest.

Current role and outcomes of ascending aortic replacement for severe nonaneurysmal aortic atherosclerosis

BACKGROUND

Severe atherosclerosis of the ascending aorta is a challenging issue potentially affecting indications for surgery, operative choices, and patients' outcome. No standard treatment has emerged to date, and uncertainties persist about criteria for selecting patients and procedures.

METHODS

Replacement of the atherosclerotic ascending aorta was performed in 64 patients at time of either aortic (n = 49), mitral (n = 21), or tricuspid (n = 7) valve surgery. Coronary artery bypass grafting was performed in 53 patients, and the majority of patients underwent combined procedures (n = 49). Mean age was 72.0 +/- 7.6 years. The expected operative mortality, by logistic European System for Cardiac Operative Risk Evaluation, was 29.0% accounting for ascending aortic replacement and 13.1% disregarding it. Circulatory arrest under deep hypothermia, eventually combined with either retrograde or antegrade brain perfusion, was required in 61 cases.

RESULTS

Early death, stroke, and myocardial infarction rates were 10.9%, 6.3%, and 7.8%, respectively. Factors univariately associated with early deaths were preoperative renal failure requiring dialysis (p = 0.001) and longer cardiopulmonary bypass (p = 0.001) and cardioplegia (p = 0.008) times. Cumulative survival at 1, 3, and 5 years was 86% +/- 4%, 74% +/- 6%, and 68% +/- 8%, respectively.

CONCLUSIONS

Replacement of the atherosclerotic ascending aorta can be carried out at acceptable mortality rates despite the high rates of preoperative comorbidity and the significant incidence of postoperative complications.

Comprehensive approach for clamping severely calcified ascending aorta using computed tomography

A severely calcified ascending aorta is generally considered unclampable. Many surgeons have developed procedures to avoid manipulation such as cross-clamping on such calcified aorta. However, these alternatives are sometimes complicated and require a more invasive procedure than the conventional method. We assessed our comprehensive strategy for clamping of a severely calcified aorta using preoperative computed tomography (CT). We found that the extent of calcification just below the innominate artery was significantly less than that at the usual ascending aorta clamp site. After confirming that the extent of calcification just below the innominate artery was <75% of the entire circumference by preoperative CT, ascending aorta was clamped with a soft cross-clamp placed on the ascending aorta with particular care to orientate the clamp parallel to the calcification. All operations were completed under usual cardiopulmonary bypass with mild hypothermia. All patients survived surgery and no patients had a postoperative neurological complication. Our results provide important information for the management of these high-risk patients, with a comprehensive approach used to choose the appropriate option for an optimal outcome.

Safer aortic crossclamping during short-term moderate hypothermic circulatory arrest for cardiac surgery in patients with a bad ascending aorta

OBJECTIVE

Cardiac surgery in patients with severely atherosclerotic or porcelain ascending aorta is technically challenging, with markedly increased risk of atheroembolism. We describe a technique of meticulous crossclamping of a difficult aorta during short-term moderate hypothermic circulatory arrest.

METHODS

From 1997 to 2007, we found 40 patients (mean age, 70 +/- 8 years), including 14 patients undergoing hemodialysis, whose preoperative computed tomographic and intraoperative epiaortic ultrasonographic scans revealed eggshell calcification (n = 15) or protruding atheromas (n = 25) of the ascending aorta. They underwent cardiac surgery (aortic, 31 patients; mitral, 3 patients; both, 5 patients; and coronary alone, 1 patient) by means of meticulous crossclamping during hypothermic circulatory arrest for 3.4 +/- 1.5 minutes at a rectal temperature of 29.0 degrees C +/- 2.3 degrees C. During hypothermic circulatory arrest, we performed only internal inspection to identify the safe location of crossclamping in 21 patients, whereas we required debridement of calcification or atheroma by using the Cavitron Ultrasonic Surgical Aspirator (Tyco Healthcare, Mansfield, Mass) for safe crossclamping in 19 patients.

RESULTS

By using this technique, no patients died during the hospital stay. Stroke occurred in 1 (2.5%) patient, and transient agitation occurred in 1 patient. Re-exploration for bleeding was required in 1 patient, and wound infection occurred in 2 patients. During follow-up, with a median time of 5.2 years, the overall survival rates were 100%, 90%, and 76% at 1, 3, and 5 years, respectively. Three patients required reoperations during the follow-up period because of pseudoaneurysm in 2 patients and prosthetic valve infection in 1 patient.

CONCLUSION

Short-term moderate hypothermic circulatory arrest is quite useful for safe aortic crossclamping after internal inspection or debridement in high-risk patients with a severely atherosclerotic aorta.