Abstract
Surgical management of thoracic aortic coarctation associated with severe aortic valve disease is difficult in most cases. As staged procedures are associated with a higher rate of morbidity and mortality, simultaneous operative management of both lesions is desirable. From 1997 to 2001, 9 patients (8 males and 1 female with a mean age of 30.1 ± 10.4 years) with this condition underwent simultaneous ascending aorta—infrarenal abdominal aorta bypass graft and aortic valve replacement. One patient died from failure of the extracorporeal circulation during the operation. Another patient suffered from partial intestinal obstruction in the early postoperative period but was successfully treated. The underlying pathology was successfully corrected in the 8 surviving patients, whose blood pressure in the upper limbs was reduced while that in the lower limbs rose. Being easier to manage, the single-stage approach with extraanatomic bypass is safe and effective for managing this aortic complication.
Introduction
The combination of significant aortic valve disease and coarctation of the aorta presents a surgical challenge. 1 –3 There is no consensus on the optimal surgical approach for these patients. When valve replacement is performed first as part of a staged approach, there may be difficulty in reestablishing the patient's circulation in the presence of persistent left heart obstruction. A staged approach with primary repair of the coarctation, on the other hand, may produce marked hemodynamic instability and may lead to death. 2 Alternative approaches have been reported in recent years, 4 –9 where both lesions are managed simultaneously through a median sternotomy or sternotomy—laparotomy with valve replacement and insertion of an extraanatomic aortic bypass graft from the ascending aorta to the descending or abdominal aorta.
We describe here 9 patients with aortic coarctation and concomitant aortic valve abnormalities and present a review of our current single-stage surgical approach for treating this complicated condition.
Patients and Methods
Between July 1997 and December 2001, 9 patients presenting with the combination of severe aortic valve disease and coarctation of the aorta were admitted for surgical management. All of them underwent ascending aorta to infrarenal abdominal aorta bypass grafting simultaneously with aortic valve replacement.
The 8 male and 1 female patients were aged 13 to 45 years (mean, 30.1 ± 10.4 years). Their clinical diagnoses are outlined in Table 1. Their clinical presentations included headache, dizziness, breathlessness of varying degrees, and fatigue in the lower limbs after exertion. Of the 9 patients, only 2 were asymptomatic. Hypertension and loud murmur were detected during physical examination. A patient with aortic dissection presented with severe pain in his chest and back.
Preoperative Diagnosis and Surgical Procedures
Surgical procedures besides ascending aorta—infrarenal abdominal aorta bypass graft. AI = aortic insufficiency, AS = aortic stenosis, AVR = aortic valve replacement, VSD = ventricular septal defect.
The mean blood pressure of the patients in their left arm was 178/65 ± 35/8 mm Hg (range, 140 to 240 mm Hg systolic, 60 to 80 mm Hg diastolic), that in the right arm was 185/65 ± 40/8 mm Hg (range, 135 to 240 mm Hg systolic, 60 to 80 mm Hg diastolic), and in both lower limbs 46/27 ± 57/34 mm Hg (range, 0 to 130 mm Hg systolic, 0 to 80 mm Hg diastolic). Eight patients had upper extremity hypertension. The blood pressure of the lower limbs was too low to be measured in 5 patients. Diastolic murmur of grade 2/6 or 3/6 and/or systolic murmur of grade 2/6 in the aortic valve area were heard in all the patients. All of them underwent preoperative transthoracic electrocardiography and electron beam computed tomography. Mean left ventricular diastolic diameter was 67.3 ± 17.3 mm (range, 44 to 97 mm) and left ventricular ejection fraction was 52% ± 12% (range, 37% to 70%).
A median sternotomy—laparotomy was made from the upper breastbone pit to the umbilicus or to a site 2 cm below. Cardiopulmonary bypass (CPB) with hypothermia was applied during the operation. In the first 5 cases (patients 1 to 5), CPB was established with double arterial cannulation in the ascending aorta and the right femoral artery to ensure adequate perfusion proximal and distal to the coarctation during cardiac arrest for intracardiac repair. Separate dual pumps were used. Right atrial or bicaval cannulation was employed for venous return. The left ventricle was vented via the left superior pulmonary vein. Before CPB was instituted, the vascular prosthesis was grafted to the abdominal aorta. Then the intracardiac lesion was repaired on CPB. Finally, the prosthesis was grafted to the ascending aorta. However, the connection and perfusion technique employed for the separate dual pumps was a little complicated, and patient 5 died from a failure in the perfusion circuit during the operation. The surgical procedure was modified following this incident.
In the modified procedure, the ascending—abdominal aorta bypass graft was completed before single arterial cannulation was established in the ascending aorta distal to the anastomosis, while the aortic crossclamp was placed on the ascending aorta proximal to the anastomosis (Figure 1). The intracardiac lesion was then repaired on CPB. Femoral artery cannulation was thereby omitted, making it easier to manage CPB connection and perfusion. Perfusion of the lower body during cardiac arrest occurred through the bypass graft. This procedure was employed in the later 4 cases (patients 6 to 9).
Graft from the ascending aorta to the infrarenal abdominal aorta. In patients 6 to 9, arterial cannulation was applied at point A and aortic crossclamping at point B.
The infrarenal abdominal aorta was selected as the site of distal anastomosis. After heparinization (100 U·kg−1), a side-biting vascular clamp was applied and a vascular prosthesis, measuring 30 to 40 cm in length and 14 to 18 mm in diameter, was attached to the infrarenal abdominal aorta with 4/0 polypropylene running suture in an end-to-side manner. A Meadox prosthesis (Boston Scientific, Wayne, NJ, USA) was used in 7 cases and a B Braun prosthesis (Aesculap, Tuttlingen, Germany) in 2 cases. The graft was allowed to fill retrogradely, with a clamp placed on its proximal side, so that the surgeon can check for bleeding at the anastomosis. Care was taken to ensure that the anastomotic site within the abdomen was retroperitoneal and well covered with peritoneum. After that, the graft was routed around the duodenum at the ligament of Treitz and through the transverse mesocolon into the lesser sac, passing posteriorly to the stomach, and then curving anteriorly to pass through the gastrohepatic mesentery (between the stomach and the liver). It was then passed through a hole in the diaphragm to course anteriorly to the right atrium before being inserted end-to-side to the partially clamped ascending aorta.
Concomitant procedures that were performed are summarized in Table 1. Blood pressure in the upper and lower limbs was monitored during the operation. The mean duration of CPB was 107.4 ± 31.0 minutes (range, 85 to 160 minutes), with the aorta clamped for a mean period of 67.0 ± 16.5 minutes (range, 52 to 95 minutes).
Values are presented as mean ± standard deviation and were analyzed by Student's t test. Differences are considered significant at p < 0.05.
Results
Patient 5 died from failure of the extracorporeal circulation, giving a mortality rate of 11% in this group of patients. Patient 9 suffered from partial intestinal obstruction postoperatively and underwent surgery 6 days later. During the reoperation, part of the jejunum was seen trapped in the hole left by the drainage tube; the graft was intact. This patient made a good recovery.
The underlying pathology was treated successfully in the 8 surviving patients, who were discharged in good condition. The mean postoperative hospital stay was 14.3 ± 3.7 days (range, 11 to 22 days). Postoperatively, blood pressure of the upper limbs fell to 122/78 ± 12/4 mm Hg (range, 110 to 135 mm Hg systolic, 70 to 80 mm Hg diastolic), while that of the lower limbs rose to 114/75 ± 12/6 mm Hg (range, 100 to 130 mm Hg systolic, 65 to 80 mm Hg diastolic). Echocardiography showed that left ventricular diastolic diameter shrank to 49.4 ± 6.9 mm (range, 41 to 59 mm), the reduction being significant compared with the preoperative value (p < 0.01); left ventricular ejection fraction was 61% ± 9% (range, 51% to 68%).
Follow-up observation was completed for all the 8 surviving patients, with a mean follow-up period of 27 ± 21 months and a maximum of 59 months. No late graft-related complications occurred or reoperation performed. Follow-up echocardiography showed that all the grafts were patent.
Discussion
In adult patients, coarctation of the aorta is frequently associated with severe aortic valve disease. 1,2,7,10 Such pathological changes in the aortic valve tend to develop from congenital deformity such as bicuspid valve, quadricuspid valve, or abnormally developed leaves. 10 With persistent hypertension of the upper limbs, the aortic valve deteriorates rapidly and presents with aortic stenosis or regurgitation in adulthood. In adult cases of congenital coarctation of the aorta, it has been reported that, even after surgical correction, severe pathological changes in the aortic valve would still develop in about 4% of the patients. 10
Coarctation of the thoracic aorta with severe aortic valve disease poses a serious surgical challenge. For a long time, these associated congenital defects have required 2 separate surgical procedures, each with its own attendant risk and costs. Furthermore, the selection of which lesion to correct first can be of critical importance. 2 However, using the technique of extraanatomic bypass graft, simultaneous surgical management of both lesions can be achieved easily. 11
In 1974, Siderys and coworkers 12 fashioned a tube graft from the ascending aorta to the infrarenal abdominal aorta through a combined median sternotomy and laparotomy incision, successfully treating a 46-year-old woman with aortic coarctation. From then on, this bypass technique has been applied to a variety of aortic problems. 6,11,13 –15 Wukasch and colleagues 5 described a variation of the bypass graft in which the distal anastomosis was made to the supraceliac abdominal aorta. Since this procedure requires an additional laparotomy, it has not been adopted widely. 8 Vijayanagar and colleagues 4 described exposure of the descending thoracic aorta through a median sternotomy and the posterior pericardium. Through this approach, they performed an ascending—descending aorta bypass with concomitant aortic valve replacement. This procedure was adopted by some surgeons. 7 –9
In our modified procedure, although an additional laparotomy is required, the infrarenal abdominal aorta can be readily exposed in this incision, making surgical management of the distal anastomosis much easier in comparison with that of ascending—descending aortic bypass. The prosthesis extends over a comparatively long distance and bends gently, thereby avoiding a sharp angle and consequent graft obstruction that may occur.
Aortoenteric fistula and periprosthetic infections are rare but devastating complications following aortic graft surgery. Although the incidence of these complications is reported to be less than 2%, 16 its occurrence in extraanatomic vascular grafts should be considered. In most cases, when an enteric fistula from the aorta or graft develops, it is at the anastomotic site. 17–18 Since the distal anastomosis of the posterior pericardial ascending—descending aortic bypass graft is very close to the esophagus, the late development of an aortoesophageal fistula is a concern. However, for ascending aorta—infrarenal abdominal aortic bypass graft, the distal anastomosis can be embedded in a retroperitoneal position and carefully covered with peritoneum. Furthermore, whenever possible, the intraperitoneal graft itself can be wrapped with omentum. In this way, the risk of fistulization should be minimized. 17 Moreover, Robicsek's 6 technique of “very long graft” (ascending to infrarenal aorta, or ascending aorta to common femoral artery) is relatively easy to perform and is well tolerated by most patients.
Hemodynamic instability occurring early after aortic valve replacement and extraanatomic bypass of aortic coarctation has been reported. 19 This complication was believed to be due to myocardial ischemia related to low diastolic perfusion pressure in severely hypertrophied hearts. However, this phenomenon was not observed in our group of patients.
Some patients may show sustained systemic hypertension postoperatively. Possible mechanisms include altered baroreceptor function, increased sympathetic activity, and permanent changes in the arterial bed from prolonged exposure to high pressure preoperatively. 20 Therefore, the patient should be treated with appropriate antihypertensives and β-blockers to prevent graft bleeding due to the high pressure. The patient should not bend backward heavily in the early postoperative period in order to avoid graft tearing and bleeding. As the vascular prosthesis is supposed to pass the left side of Treitz's ligament and through the transverse mesocolon, it may constrict the duodenum and lead to pyloric obstruction if it is too short. Therefore, the prosthesis should be of an appropriate length. Finally, the intestines should be restored properly to avoid intestinal obstruction.
The surgical management of patients with complex coarctation of the aorta with associated cardiac disorders has to be individualized. Extraanatomic bypass graft appears to be a safe and flexible procedure that is particularly useful in adult patients when simultaneous intracardiac repair is required. Midterm results are satisfactory. Long-term evaluation is mandatory to assess the possible occurrence of specific complications associated with prosthetic materials.