Feroze Mahmood, MD
Madhav Swaminathan, MD
Section Editors
CARDIAC ANESTHESIA FELLOWS EDUCATION
Dalia A. Banks, MD, FASE
Aortic Stenosis and Coronary Artery Disease ... and a Challenging Aorta
Brandi A. Bottiger, MD, Robert D. Davis, MD, Robert C. Swift MD, Madhav Swaminathan MD, FASE, FAHA
Departments of Anesthesiology and Surgery, Duke University Health System, Durham, NC
Address reprint requests to Madhav Swaminathan, MD, FASE, FAHA, Department of Anesthesiology, Division of Cardiothoracic Anesthesiology and Critical Care Medicine, Box 3094/5691F HAFS Building, Duke University Health System, Durham, NC 27710. E-mail: swami001@mc.duke.edu
Key words: aortic stenosis, coronary artery disease
A 77-YEAR-OLD man presented to an outside hospital with the chief complaint of chest pain that radiated to his jaw. He had a known history of coronary artery disease for which he had coronary stents placed 6 years previously. He was diagnosed with a non-ST elevation myocardial infarction and after stabilization was transferred to the authors' facility for further evaluation and management. Transthoracic echocardiography showed preserved left ventricular systolic function with an estimated ejection fraction of >55%, a grade I diastolic relaxation abnormality, normal wall motion, mild left ventricular hypertrophy, and a moderately stenosed aortic valve (45 mmHg peak and 24-mmHg mean transvalvular gradient) with thickened, calcified leaflets. Coronary angiography at the transferring hospital showed severe 3-vessel disease.
His past medical history was significant for hypertension, hyperlipidemia, tobacco abuse (65-pack-year history), and carotid artery disease with previous left carotid endarterectomy. He denied complications with anesthesia for his past surgeries. Based on his presentation and imaging studies, the patient was scheduled for coronary artery bypass graft (CABG) surgery and aortic valve replacement (AVR) on cardiopulmonary bypass (CPB).
Preoperative laboratory studies were unremarkable except for anemia (hemoglobin, 10.0 g/dL) and an elevation in creatinine (1.6 mg/dL). He was on a heparin infusion. He was taken to the operating room, and after placement of appropriate monitors, general anesthesia was induced uneventfully and the airway was secured in typical fashion.
Intraoperative Transesophageal Echocardiographic Findings
An intraoperative transesophageal echocardiographic (TEE) examination was performed on an ie-33 ultrasound system with an X7-2t TEE probe (Philips Medical Systems, Andover, MA). The principal findings were the following: (1) preserved left ventricular systolic function, (2) estimated ejection fraction of >55%, (3) a thickened and mildly calcified aortic valve with turbulent flow by color-flow Doppler (Fig 1,left panel), (4) a peak transvalvular gradient of 37 mmHg with a mean gradient of 22 mmHg (Fig 1, right panel), and (5) severe atherosclerotic disease of the descending aorta and aortic arch with multiple atheromatous plaques (Fig 2). Calcified plaques in the ascending aorta also were noted. The surgeon determined by manual palpation that there was dense calcification of the ascending aorta in the region where manipulation (ie, cannulation, cross-clamping, proximal anastomosis, and aortotomy) was planned, the so-called "porcelain aorta" (see supplementary video available online).
Discussion
The following challenges were met in this case.
1. Should the aortic valve be replaced? If yes, how should the surgery be conducted? If no, what are the
implications of residual aortic stenosis on postoperative outcome?
2. How should the CABG surgery be conducted? Should it be on-pump CABG surgery? What are the possible
cannulation sites? Where are the possible proximal anastomotic sites? Should it be off-pump CABG surgery?
Where are the possible proximal anastomotic sites? What are the advantages versus the disadvantages of off-
pump CABG surgery?
3. What are the risks of perioperative stroke with a calcified aorta?
Options
The following options were considered: (1) CABG surgery and AVR with right axillary cannulation for arterial access instead of direct aortic cannulation; (2) CABG surgery, AVR, and ascending aorta with root replacement under deep hypothermic circulatory arrest; (3) CABG surgery only on CPB with right axillary cannulation for arterial access instead of direct aortic cannulation; and (4) off-pump CABG surgery only with minimal aortic manipulation.
Strategy
After extensive discussions among the referring cardiologist, surgeon, and Anesthesiologist, a decision was made not to replace the aortic valve and proceed with off-pump CABG surgery. The patient had 3 coronary bypass grafts performed, including a left internal mammary artery to the left anterior descending, and saphenous vein grafts to the first marginal and right posterior lateral first branch. One saphenous vein graft was anastomosed to the proximal ascending aorta using a minimally invasive technique (Heartstrings II; Maquet Cardiovascular LLC, Wayne, NJ) without the need for a partial aortic cross-clamp. The proximal anastomosis of the second vein graft was performed on the first vein graft, thereby allowing for only a single aortic proximal anastomotic site.
Fig 1 The image on the left shows the midesophageal aortic valve long-axis view with color-flow Doppler across the aortic valve indicating turbulent transvalvular flow. The image on the right represents continuous wave spectral Doppler across the aortic valve in the deep transgastric long-axis view. The measurements are described in the text.
Rationale
According to the Society of Thoracic Surgeons (STS) risk score, his calculated overall mortality risk was 5.1%, morbidity or mortality risk was 34.2%, and stroke risk was 3.9% for CABG surgery and AVR. Without the AVR procedure, his risks for the same outcomes were 3.5%, 26.1%, and 2.4%, respectively. However, the STS risk calculator does not account for the severity of aortic stenosis or a porcelain aorta. This was also balanced with the risk of progression of aortic stenosis without surgical intervention. Given the patient's age and comorbidities, combined with the high risk of morbidity and mortality accompanying the AVR, it was believed that the aortic valve should not be replaced. First, there likely would be limited reduction in the transvalvular gradient from a prosthetic valve and therefore limited benefit in this patient with a mean gradient of 22 mmHg. Second, with close postoperative follow-up, the aortic stenosis could be monitored, and, if required, a percutaneous replacement could be feasible in the future. The off-pump approach was chosen to eliminate cannulation and limit aortic manipulation to reduce the stroke risk. Although the STS risk calculator does not account for the off-pump technique to reduce risk, aortic manipulation in this case was believed to be the most significant factor rather than CPB itself. The potential risk was that the patient may not tolerate surgical handling of the heart or beating-heart surgery and CPB may need to be initiated emergently. A "no-touch" technique of vein graft anastomosis was used to minimize aortic manipulation while retaining the quality of revascularization.
Fig 2 The descending aorta is shown simultaneously in the short-axis (SAX) and long-axis (LAX) views. Significant atheromatous disease is indicated by the arrows in the image.
Postoperative Course
The patient tolerated the procedure well without any complications or the need for inotropic support. After the procedure, he was transferred to the postoperative cardiac surgical intensive care unit in stable condition. In the immediate postoperative period, he continued to do quite well and had a routine discharge 5 days after surgery.
Summary
In summary, this case highlights how a heavily calcified aorta, which was initially detected with transesophageal echocardiography, limited the management of a patient with combined aortic valve stenosis and coronary artery disease. These findings led to a complete change in surgical plan guided by a multidisciplinary discussion of all possible approaches and their implications. Fortunately, the patient had an uneventful in-hospital course as planned. A video summarizing the case including TEE video clips is also presented.
