Design  Retrospective review case series.

Setting  Large, private, urban teaching hospital.

Patients  All adult patients with aortic disease that involved the distal aortic arch, the descending thoracic aorta, or the thoracoabdominal aorta who underwent resection and graft replacement of the diseased segment via LHB or TCA at our institution from 1989 to 2001 are included in this study. A total of 59 patients were evaluated: 10 had descending thoracic aneurysms, 20 had thoracoabdominal aneurysms, 22 had chronic type B dissections, 4 had acute type B dissections, and 3 had adult coarctations.

Interventions  In 1989 to 1994, LHB was primarily used; in 1994 to 2001, TCA was primarily used.

Main Outcome Measures  Renal failure, 30-day operative mortality, paraplegia, and any other morbidities.

Results  A significant decrease occurred in the incidence of postoperative renal failure from 15% (3/20) in patients who underwent LHB to 0% (0/39) in patients who underwent TCA (P = .04). Furthermore, a significant decrease occurred in the 30-day operative mortality, which decreased from 20% (4/20) in patients who underwent LHB to 5% (2/39) in patients who underwent TCA (P = .04). Postoperative paraplegia decreased from 5% (1/20) in patients who underwent LHB to 2.6% (1/39) in patients who underwent TCA (P > .99).

Conclusions  Our use of TCA in the resection and replacement of the diseased thoracoabdominal and descending thoracic aorta has produced excellent results. Our patients have experienced no postoperative renal failure and a low 30-day operative mortality. The use of TCA in this patient population is a viable option for surgeons comfortable with the technique.

Furthermore, the occurrence of renal failure following surgical repair of thoracoabdominal aortic aneurysms and descending thoracic aortic aneurysms is a topic of significant interest. Studies^{5, 7, 17-19} report the incidence of renal failure that occurs following this surgery as remaining high and having an association with high early and late mortality rates.

The safety and efficacy of hypothermic TCA for the resection of the descending and thoracoabdominal aorta have been reported in recent years. However, compared with the LHB technique, no other reported series on TCA has, to our knowledge, shown elimination of postoperative renal failure, a significantly lower overall 30-day operative mortality, and a trend toward lower postoperative paraplegia. In the present series, we sought to compare the morbidity and mortality associated with replacement of the descending and thoracoabdominal aorta using elective TCA vs LHB performed at our institution.

METHODS

View this table: [in this window] [in a new window] Table 1. Types of Aortic Disease Treated

View this table: [in this window] [in a new window] Table 2. Clinical Characteristics and Comorbidities of the 2 Groups

RESULTS

The TCA times for the different diagnoses encountered ranged from an average of 46.0 minutes for acute type B dissections to an average of 35.0 minutes for coarctation of the aorta (Table 3).

View this table: [in this window] [in a new window] Table 3. TCA Times for All Aortic Diseases Treated by TCA

MORTALITY

A statistically significant difference in mortality occurred between the 2 groups. The overall 30-day mortality rate for patients undergoing surgery via TCA was 5% (2/39) and stayed the same for the hospital mortality. This is in contrast to patients who underwent LHB, who had a 30-day mortality of 20% (4/20) (P = .04) (Figure 1). In the TCA group, 2 deaths occurred. One patient with a descending thoracic aneurysm died intraoperatively of pump failure, subsequent to rupture and hemorrhage. Another patient in the TCA group, who had a thoracoabdominal aneurysm, died on the fifth postoperative day subsequent to multiorgan failure. In the LHB group, 4 deaths occurred: 2 patients with chronic type B dissections and 2 with thoracoabdominal aneurysms. In the 2 patients with chronic type B dissections, one died intraoperatively due to pump failure subsequent to arrhythmia (ventricular tachycardia/fibrillation), whereas the other patient (who had a chronic type B dissection) died on the first postoperative day due to arrhythmia (ventricular tachycardia/fibrillation). Of the 2 patients with thoracoabdominal aneurysms, one died on the 18th postoperative day subsequent to hemorrhage, whereas the other died on the 20th postoperative day subsequent to renal failure.

View larger version (47K): [in this window] [in a new window] Figure 1. Thirty-day operative mortality decreased from 20% (4/20) with left heart bypass (LHB) to 5% (2/39) with total circulatory arrest (TCA) (P  = .04).

NEUROLOGIC COMPLICATIONS

No significant difference in neurologic complications between the 2 groups was observed. Paraplegia occurred in 1 (3%) of 39 patients undergoing surgery via TCA compared with 1 (5%) of 20 patients undergoing LHB (P > .99) (Figure 2). The patient undergoing surgery via TCA had a chronic type B dissection, whereas the patient undergoing surgery via LHB had an acute type B dissection. Postoperative hemiparesis, with return to normal neurologic function before discharge, was found in 3 (8%) of 39 patients undergoing surgery via TCA and in 1 (5%) of 20 patients undergoing LHB (P > .99). Stroke with a resulting focal neurologic deficit occurred in 4 (10%) of the 39 patients undergoing TCA vs 1 (5%) of the 20 patients undergoing LHB (P = .65). Interestingly, among the patients undergoing surgery via TCA with neurologic sequelae, all had chronic type B dissections. The one patient who suffered neurologic complications in the LHB group had a thoracoabdominal aneurysm.

View larger version (45K): [in this window] [in a new window] Figure 2. Postoperative paraplegia decreased from 5% (1/20) with left heart bypass (LHB) to 3% (1/39) with total circulatory arrest (TCA) (P > .99).

PULMONARY DYSFUNCTION

No significant difference was noted between the 2 groups with respect to pulmonary dysfunction. Respiratory failure that required prolonged (>48 hours) mechanical ventilation was required in 6 (15%) of the 39 patients undergoing TCA, whereas 4 (20%) of the 20 patients undergoing LHB required prolonged ventilatory support (P = .72). Tracheostomy was required in 4 (10%) of the 39 patients undergoing TCA and in 2 (10%) of the 20 patients in the LHB group (P > .99).

RENAL DYSFUNCTION

Renal failure with resultant elevated creatinine levels occurred in no patients undergoing TCA in contrast to 3 (15%) of the 20 patients in the LHB group (P = .04) (Figure 3). Postoperative renal dysfunction was defined as a creatinine level 1.5 times the preoperative level or higher.

View larger version (46K): [in this window] [in a new window] Figure 3. The incidence of postoperative renal failure decreased from 15% (3/20) with left heart bypass (LHB) to 0% (0/39) with total circulatory arrest (TCA) (P = .04).

COMMENT

Often TCA is used when the patient is deemed at high risk for potential neurologic complications, such as the risk of paraplegia from spinal cord ischemic injury in patients with extensive descending thoracic aortic aneurysms or in patients with Crawford type I, II, or III thoracoabdominal aortic aneurysms.^9-12 Certainly, another circumstance that calls for the use of TCA is the presence of atherosclerosis, where the patient’s aorta is severely calcified and cannot be safely cross-clamped for fear of possible embolic complications and stroke.^{13, 15} Also, the issues of renal failure and mortality following TCA, compared with other techniques, are controversial and important topics with respect to thoracic and thoracoabdominal aortic repair. Some studies^{5, 18} have suggested that the rate of renal failure remains high following these procedures and that it may even have an association with increased mortality in this patient population.

We reviewed our results for all operations performed on the distal aortic arch, descending thoracic aorta, and thoracoabdominal aorta at our institution. We compared outcomes between our previous technique of LHB from 1989 to 1994 and results after our switch to the routine use of profound hypothermic TCA from 1994 to 2001 for the same conditions. Although our 2 study groups are separated by almost a decade, we believe this comparison provides useful information regarding the safety and efficacy of our technique.

Profound hypothermic TCA has been used by many surgeons for a variety of conditions. Its use has often been described in the replacement of the aortic arch, descending thoracic aorta, and thoracoabdominal aorta.^{5, 10, 12, 17, 19-24} In addition, other authors^2-4,8-14,16 have reported extensively on the use of hypothermic TCA and the advantages conferred by this technique.

Debate exists over mortality associated with the use TCA. Some studies, such as the one by Safi et al,⁵ cite a higher mortality rate associated with the use of hypothermic TCA, whereas other studies note a decreased mortality rate^10-12 or at least no increase or difference in mortality with or without the use of TCA.¹ In our series, we found a significant difference in mortality between the TCA and LHB groups, with patients undergoing TCA having a mortality rate of only 5% compared with 20% in patients undergoing LHB.

Hypothermia has been shown to increase the tolerance of neurologic tissue to ischemia, namely, a decrease in spinal cord susceptibility to ischemic damage and paralysis.^{3, 7, 9, 14-16} This added protection and increased duration of tolerable spinal cord ischemia conferred by hypothermia allows for more time to reimplant lumbar and intercostal vessels. The profound hypothermia also provides protection for the brain, with decreased cerebral ischemic injury.¹² Our study did not show a significant difference between TCA and LHB with respect to neurologic sequelae.

A notable benefit provided by TCA in addition to brain and spinal cord protection is the added protection of the kidneys and abdominal viscera in the surgical repair of the aortic arch and descending thoracic aortic dissections and thoracoabdominal aortic aneurysms.^10-12 Some studies¹⁸ have not shown an improvement in renal protection with the use of TCA and report the incidence of renal failure that occurs with this surgery as remaining high and having an association with high early and late mortality rates.

The use of TCA in our study completely eliminated the incidence of postoperative renal failure. The difference in renal failure was statistically significant between the 2 groups, with a 0% rate of renal failure in patients undergoing TCA compared with a 15% rate of renal failure with LHB (P = .04).

In summary, this single institution comparison of results between profound hypothermic TCA and LHB techniques provides useful information regarding the safety and efficacy of our technique in the resection of the distal aortic arch, descending thoracic aortic dissections, and thoracoabdominal aneurysms. We observed that the use of TCA in the resection of the distal aortic arch and descending and thoracoabdominal aorta has eliminated renal failure and significantly decreased the 30-day operative mortality. Furthermore, we observed no difference in neurologic outcomes even though we did not use additional adjuncts for spinal cord protection in patients undergoing TCA. We recommend the routine use of TCA and believe that this technique is safe, has good results, and should be used for patients who require distal aortic arch and descending and thoracoabdominal aortic surgery.

AUTHOR INFORMATION

Accepted for Publication: May 31, 2004.

Previous Presentation: This study was presented at the 75th Annual Session of the Pacific Coast Surgical Association; February 15, 2004; Maui, Hawaii; and is published after peer review and discussion.