Surgical management of atherosclerotic aortic arch aneurysms using selective cerebral perfusion: 7-year experience in 52 patients

Deep Hypothermia and Circulatory Arrest in Adults

Brain protection during cardiopulmonary bypass has been the subject of intense research. Deep hypothermic circulatory arrest (DHCA) continues to be used for that goal during complex aortic arch and large intracranial aneurysm surgeries. The anesthetic management for adult patients undergoing these types of procedures requires specific knowledge and expertise. Based on our experience and review of the current literature, the authors highlight the key areas of the anesthetic plan, discussing the risk factors associated with adverse neurologic outcome as well as the rationale for decisions regarding specific monitors and medications. In the conclusion an anesthetic protocol for adult patients undergoing DHCA is suggested.

Right axillary arterial perfusion for descending thoracic or thoracoabdominal aortic aneurysm repair with open proximal anastomosis through left thoracotomy

BACKGROUND

We examined the effectiveness of right axillary arterial perfusion through an interposed Dacron graft in the prevention of cerebral embolism or complications related to ascending aortic cannulation in open proximal anastomosis technique of descending thoracic aortic aneurysm (TAA) or thoracoabdominal aortic aneurysm (TAAA) repair under deep hypothermic circulatory arrest through left thoracotomy.

METHODS

Between May 2000 and August 2012, 44 patients underwent TAA or TAAA repair using open proximal technique under DHCA. These patients were divided into two groups for evaluation of the effectiveness of right axillary arterial perfusion. Group A included patients who underwent TAA or TAAA repair with ascending aortic cannulation (n=15). Group B was composed of patients who had TAA or TAAA repair with right axillary arterial perfusion through the interposed Dacron graft (n=29).

RESULTS

Mortality in this series was 4.5% (2 of 44 patients; 1 in each group); wherein, the causes were sepsis due to graft infection and aortic dissection (Stanford type A). The incidence rates of cerebral embolism were 27 % (4 of 15 patients in group A) and 3.4% (1 of 29 patients in group B) (p=0.0392, Fisher's exact test). The rates of complications in relation to the aortic cannulation site (dissection or bleeding) were 13% (2 of 15 patients in group A) and 0% (0 of 25 patients in group B).

CONCLUSIONS

Right axillary perfusion facilitates easy evacuation of air and allows prompt recommencement of upper body circulation. Consequently, it minimizes the risk of cerebral embolism or complications in relation to aortic cannulation through left thoracotomy.

Vertebral artery variations in thoracic aortic patients

OBJECTIVES

Arterial variation is common in the vertebral artery, and simple occlusion of the left subclavian artery may result in brain infarction, especially when it terminates in the posterior inferior cerebellar artery (PICA). We report the results of preoperative vertebral artery evaluation by magnetic resonance angiography (MRA) and its impact upon operative strategy.

METHODS

Among the 214 patients who underwent thoracic aortic surgery from 2009 through 2012, 159 patients with preoperative MRA were retrospectively analysed. Patients' age ranged from 35 to 88 (median 72), 122 were male and 115 had degenerative aneurysms. Prevalence rates of vertebral artery variations and occlusive lesions were reported, together with operative strategies and outcomes.

RESULTS

There were 19 hypoplasia (12%), 10 PICA termination (6%) and 12 occlusive lesion (8%) on the right vertebral artery and 10 hypoplasia (6%), 5 PICA termination (3%), 7 direct arch origin (4%) and 3 occlusive lesion (2%) on the left. Two of the seven arch-originated arteries terminated in the PICA. In aortic arch replacement, these were reconstructed together with the left subclavian artery while hypothermia was maintained. During thoracic endovascular aortic repair with Zone-2 proximal landing, debranching bypass was employed to preserve left subclavian perfusion when there was PICA termination, hypoplasia or occlusive lesion. In 1 patient with hypoplasia between the basilar artery and the left PICA, bypass was added immediately after deployment because radial pressure dropped critically. No brain infarction occurred with this strategy.

CONCLUSIONS

PICA termination and right side hypoplasia/occlusive lesion, where left subclavian perfusion is important for brain protection, is present in ∼ 30%. Left vertebral artery that originated from the arch should be managed with care, because PICA termination is highly prevalent.

Extensive deployment of the stented elephant trunk is associated with an increased risk of spinal cord injury

OBJECTIVE

Thoracic aortic aneurysm repair with the stented elephant trunk technique seems to be associated with an increased risk of spinal cord injury. We investigated whether severe atherosclerosis of the distal landing zone or extensive deployment of the stented elephant trunk is associated with increased risk of spinal cord injury.

METHODS

Twenty-five patients underwent thoracic aortic aneurysm repair with the stented elephant trunk technique. The study population included 19 men and had a mean age of 73 +/- 7 years. All patients underwent a median sternotomy with cardiopulmonary bypass and selective cerebral perfusion. The elephant trunk was fixed with a Z-stent distal to the aneurysm during hypothermic circulatory arrest. Thirteen patients underwent concomitant total aortic arch replacement.

RESULTS

Six (24%) patients had spinal cord injury. The presence of severe atherosclerosis at the distal landing zone demonstrated a tendency to increase the incidence of spinal cord injury (36% vs 9%, P = .1218). More distal deployment of the stented elephant trunk was significantly associated with increased risk of spinal cord injury (T8.0 +/- 0.6 vs T6.5 +/- 1.1, P = .0043). Univariate logistic regression analysis identified a history of abdominal aortic aneurysm repair (P = .0296) and the vertebral level of the distal landing zone (P = .0249) as significant independent risk factors for spinal cord injury, and only the latter was significant in multivariate analysis (P = .0396). The combination of a distal landing zone of T7 or greater and a history of abdominal aortic aneurysm repair was the strongest predictor for spinal cord injury (71% vs 6%, P = .0047).

CONCLUSIONS

Spinal cord injury after stented elephant trunk deployment might be related to occlusion of the excessive intercostal arteries or thromboembolism. Patients with a history of abdominal aortic aneurysm repair who require extensive deployment of the stented elephant trunk seem to be at a higher risk for spinal cord injury.

Arterio-jugular Differences in Serum S-100β Proteins in Patients Receiving Selective Cerebral Perfusion

PURPOSE

The early increase in serum S100beta after cardiopulmonary bypass (CPB) seems to be derived from an extracerebral source. To exclude contamination, we investigated the arterio-jugular differences in S100beta levels in patients receiving selective cerebral perfusion (SCP). We also evaluated the brain-protective effect of SCP by comparing the arterial S100beta levels with those in patients undergoing coronary artery bypass grafting (CABG).

METHODS

We measured arterial and jugular venous levels of S100beta in ten patients undergoing aortic arch repair with SCP for up to 12 h postoperatively (SCP group). We also measured arterial levels of S100beta in nine patients undergoing CABG (CPB group).

RESULTS

There was no incidence of hospital death or stroke. The arterial levels of S100beta in both groups were comparable and peaked just after the conclusion of CPB. The arterial and jugular venous levels of S100beta were almost equivalent. The arterio-jugular differences in S100beta levels were negligible, even in our SCP-group patient with postoperative delirium, who had a peak value three times higher than the other patients.

CONCLUSIONS

The arterio-jugular differences in S100beta did not clarify the origin of their increase. Thus, measuring the jugular venous levels of S100beta in patients without postoperative clinical neurological deterioration would be of little benefit. However, SCP seems to protect the brain against S100beta release as effectively as conventional CPB.

Direct cannulation of the common carotid artery during the ascending aortic or aortic arch replacement

OBJECTIVE

To evaluate cerebral perfusion using direct cannulation into the common carotid artery. A new technique is needed to protect brain ischemic injury during ascending aortic or aortic arch replacement.

METHODS

This technique was evaluated for patients who would have difficulty maintaining adequate cerebral perfusion during surgery. The procedure was performed when patients had the following diagnoses: pseudoaneurysm formation in contact with the sternum with the risk of aneurysmal rupture (n = 5), acute aortic dissection with compression of the true lumen of the innominate artery by the pseudolumen (n = 3), or a large volume of thrombus in the lumen of the aneurysm with the risk of cerebral thromboembolism if standard extracorporeal circulation was used (n = 2). The perfusion catheter was cannulated into one side of the common carotid artery (right side: n = 6, left side: n = 4) and mean perfusion flow rate was found to be 175 mL/min. The operative procedures consisted of ascending aortic and aortic arch replacement with coronary artery bypass grafting in six patients, ascending aortic replacement in 2 patients, and innominate artery reconstruction/innominate artery and right subclavian artery reconstruction in one patient.

RESULTS

No cerebral accidents or deaths occurred while patients were hospitalized. We have followed up patients for a mean of 2.1 years (maximum 3.6 years), with no complications noted from the surgical procedure.

CONCLUSIONS

Direct cannulation of the common carotid artery is a simple, safe, and acceptable cerebral protection for patients undergoing aortic or aortic arch replacement procedures in the patients with these specific conditions.

Cannulation of the axillary artery for cardiopulmonary bypass: safeguards and pitfalls

BACKGROUND

The ascending aorta is the customary site for arterial cannulation for cardiopulmonary bypass. Favorable experience at our institution and elsewhere using axillary artery cannulation in treating type A aortic dissections has caused us to broaden our indications for using this site for arterial cannulation for cardiopulmonary bypass.

METHODS

Medical records, operative notes, and perfusion records were reviewed in all patients in whom the axillary artery was cannulated directly or by a graft for cardiopulmonary bypass from January 1, 2000 through August 30, 2002.

RESULTS

Seventy-five patients underwent axillary artery cannulation during the 32-month interval. Eleven patients had ascending aortic dissections, 20 had extensively diseased ascending aortas, and 44 were individuals undergoing repeat cardiac procedures. The right axillary artery was used in 72 patients and the left in 3. In 16 patients the artery was cannulated directly, and in 59 the arterial cannula was inserted into a prosthetic graft that had been anastomosed to the axillary artery. Axillary artery cannulation was satisfactory in 95% (71 of 75) of the cases in which it was used.

CONCLUSIONS

Cannulation of the axillary artery for cardiopulmonary bypass is a dependable approach for procedures including reoperations, aortic dissections, and extensively diseased ascending aortas.

Isolated cerebral perfusion for intraoperative cerebral malperfusion in type A aortic dissection

Cerebral malperfusion due to expansion of a false lumen can occur acutely during aortic repair when retrograde femoral perfusion is initiated. We detected this catastrophe by a rapid decrease in regional cerebral oxygenation and successfully treated it by immediate isolation of the cerebral circulation from the systemic circulation. The surgical management, including the above technique, for this rare event is described.

Emergency surgery results in life-threatening thoracic aortic disease

OBJECTIVE

Emergency surgery for thoracic aortic aneurysm continues to involve high mortality. We review our experience in emergency surgery for life-threatening thoracic aortic disease.

METHODS

Between September 1994 and June 2000, 65 consecutive patients--38 men and 27 women aged 18 to 84 years (mean: 64.3 years)--underwent emergency surgery for thoracic aortic disease. Of these, 40 (61%) were treated for acute type A dissection, 16 (25%) for aortic rupture, and 9 (14%) for impending aneurysmal rupture. Ascending aorta repair was conducted in 21, aortic arch repair in 30, distal arch repair in 2, descending aorta repair in 9, and thoracoabdominal aorta repair in 3. Of the 65, 42 were under 70 years old and 23 were 70 years of age and older.

RESULTS

Overall, 8 (12%) died in the hospital--3 (7.5%) of acute type A dissection, 3 (19%) of ruptured aneurysm, and 2 (22%) of impending rupture. Of these, 3 (7.1%) were younger than 70 years and 5 (22%) 70 years and older. The following perioperative factors significantly influenced hospital mortality: pump time (p = 0.019), postoperative severe cardiac failure (p = 0.006), postoperative respiratory failure (p = 0.045), and postoperative acute renal failure (p = 0.0007). Of the 57 survivors followed up for an average of 2.8 years (1 month to 6 years), 3-year survival was 73% overall--88% in patients younger than 70 years and 38% in those 70 years and older (p = 0.0004). Seven of the 9 patients suffering strokes during surgery died in the hospital (2) or after discharge (5). Overall hospital and late deaths involved 2 of 4 patients younger than 70 years and all of 5 patients 70 years and older.

CONCLUSION

The majority of patients undergoing emergency surgery for life-threatening thoracic aortic disease can undergo graft replacement with acceptable mortality, morbidity, and late survival, but early and late mortality for patients older than 70 remains extremely high.

Simulation study of a selective cerebral perfusion system with a single centrifugal pump

We previously successfully developed a simple nonroller extracorporeal circulation system (NRECC). In aortic arch surgery, more than two pumps are generally used for systemic perfusion and selective cerebral perfusion (SCP); we developed a new pressure-dependent perfusion system for SCP based on our NRECC and operated by a single centrifugal pump. The cerebral perfusion line was branched from the main perfusion line, and one 15 French and two 12 French cannulae were used for SCP. The perfusion pressure was regulated with a tube occluder. Afterload was changed from 30 to 80 mm Hg, the pressure of the SCP line was increased from 80 to 200 mm Hg, and flow volume was measured. When the afterload was set at 50 mm Hg, according to the increase of perfusion from 80 to 200 mm Hg, the flow volume of the 15 French cannula increased from 280 to 950 ml/min. Under the same conditions, flow volume of the 12 French cannula increased from 160 to 560 ml/min. Sufficient flow volume of the SCP lines was obtained when the SCP line pressure was over 80 mm Hg. As a result of the increased perfusion pressure, the flow volume showed a direct increase. These findings suggest that aortic arch surgery is possible using this SCP system.

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.