Ann Thorac Surg 2006;81:2079-2083
© 2006 The Society of Thoracic Surgeons
Original article: Cardiovascular
Total Aortic Arch Replacement in Patients With Arch Vessel Anomalies
Kazuchika Suzuki, MD, PhD
*
,
Teruhisa Kazui, MD, PhD,
Abul Hasan Muhammad Bashar, MBBS, PhD,
Katsushi Yamashita, MD, PhD,
Hitoshi Terada, MD, PhD,
Naoki Washiyama, MD, PhD,
Takayasu Suzuki, MD
First Department of Surgery, Hamamatsu University School of Medicine, Hamamatsu, Japan
Accepted for publication December 20, 2005.
* Address correspondence to Dr K. Suzuki, The First Department of Surgery, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu, 431-3192, Japan. (Email: kazuchi{at}fj9.so-net.ne.jp).
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Abstract
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BACKGROUND: The presence of anomalous arch vessels has considerable impact on aortic arch reconstruction techniques and cerebral protection methods when the separated graft technique is adopted to perform total arch replacement. We analyzed our experience of total arch replacement in patients with arch vessel anomalies.
METHODS: Among the 220 patients undergoing total arch replacement at our institution, 21 patients (9.5%) had various arch vessel anomalies. Common brachiocephalic trunk was found in 8 patients (3.6%); an isolated left vertebral artery in 9 (4.1%); aberrant right subclavian artery in 3 (1.4%); and coexistent common brachiocephalic trunk and isolated left vertebral artery in 1 (0.5%). In 4 of the 9 patients with isolated left vertebral artery, preoperative diagnosis was possible with magnetic resonance angiography or three-dimensional computed tomography. In cases with common brachiocephalic trunk, total arch replacement could be performed with the usual techniques after separating the innominate and left common carotid arteries from each other. The isolated left vertebral artery was anastomosed to the left subclavian artery graft in 7 patients and to the native left subclavian artery in 2. In the aberrant right subclavian artery variety, a distal aortic anastomosis was performed distal to the orifice of this anomalous artery. The aberrant vessel was reconstructed on the right side of the trachea and esophagus.
RESULTS: There was no early or in-hospital mortality. No neurologic complication attributable to the arch vessel anomalies was found.
CONCLUSIONS: A precise preoperative diagnosis is very important for the selection of an appropriate surgical strategy in patients with arch vessel anomalies. Magnetic resonance angiography and three-dimensional computed tomography may be useful diagnostic tools in these patients.
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Introduction
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According to available data, the incidence of various types of arch vessel anomalies is about 17% among the general population in Japan [1]. Among the American population, the incidence is reported to be as high as 34% [2]. Although it is rare for the anomalous arch vessels to cause symptoms that are severe enough to necessitate surgical intervention, their presence influences the total arch replacement (TAR) operations to a significant extent. This is particularly true when the TAR is carried out using the separated graft technique, which otherwise offers a number of advantages over the en-bloc repair technique. With the separated graft technique, the arch vessel anastomoses can be performed at a site that is free from atherosclerotic plaques or dissection. Control of bleeding from the arch vessel anastomotic sites is also easier with the former technique. Although the difference between the two techniques is not always significant in terms of major outcome variables [3], we prefer the separated graft technique popularized by Kazui and colleagues [4] for its above-mentioned advantages. The usefulness of this technique is getting increasing recognition as evident from the growing number of centers that now use the technique for TAR [5, 6]. With this technique, however, the presence of anomalous arch vessels often requires changes in the arch reconstruction technique as well as the cerebral protection methods. Although reports of TAR in patients having arch vessel anomalies are increasing [7–12], there is no literature summarizing the various aspects of TAR in such patients. In this study, we analyzed our experience with TAR in this specific group of patients to assess the difficulties encountered during surgery.
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Patients and Methods
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The study was approved by the institutional review board of the Hamamatsu University School of Medicine. Informed written consent was also obtained from each individual patient. Between March 1997 and November 2005, 220 patients underwent TAR for atherosclerotic aneurysm or aortic dissection at our institution. Of them, a total of 21 patients (9.5%) had various arch vessel anomalies in the presence of a normal left aortic arch. A classification of the arch vessel anomalies is shown in Figure 1. Routine preoperative investigations in nonemergent cases included enhanced computed tomographic scan and digital subtraction angiography, whereas magnetic resonance angiography and three-dimensional computed tomographic scan were used only in the recent cases. Common brachiocephalic trunk (CBT), in which the left common carotid artery and the innominate artery originate from a common trunk (Fig 1A) was found in 8 patients (3.6%). Isolated left vertebral artery (ILVA), which is defined as a left vertebral artery taking off directly from the aortic arch (Figs 1B, 2), was present in 9 patients (4.1%). Although preoperative digital subtraction angiography was routinely performed, it could not give the conclusive diagnosis of the ILVA in any of the patients. In 4 of the 9 patients, the anomaly was diagnosed preoperatively: 3 with the help of magnetic resonance angiography and 1 with three-dimensional computed tomographic scan. Aberrant right subclavian artery (ARSCA), which is a right subclavian artery arising from the proximal descending aorta as the fourth aortic arch branch and passing behind the esophagus and trachea (Fig 1C), was found in 3 patients (1.4%). The remaining 1 patient (0.5%) who had both CBT and ILVA (Fig 1D) was included in the ILVA group. The patient characteristics in the three groups are shown in Table 1. There were no symptoms attributable to the arch vessel anomalies except in 1 patient with ARSCA, who complained of dysphagia.
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Fig 1. (A) Common brachiocephalic trunk (CBT); left common carotid artery (LCCA) and innominate artery (IA) originate from the common trunk. (B) Isolated left vertebral artery (ILVA); a left vertebral artery arising directly from the aortic arch. (C) Aberrant right subclavian artery (ARSCA); a right subclavian artery arising from the proximal descending aorta as the fourth aortic arch branch and passing behind the esophagus and trachea. (D) Coexistent common brachiocephalic trunk and isolated left vertebral artery.
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Fig 2. Preoperative magnetic resonance angiogram showing the dominant isolated left vertebral artery (arrow).
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All patients underwent TAR under moderately hypothermic circulatory arrest and with the aid of antegrade selective cerebral perfusion (SCP). The details of our cerebral protection and arch reconstruction techniques have been described elsewhere [13]. In brief, after median sternotomy, cardiopulmonary bypass was established with the arterial inflow through the ascending aorta or right axillary artery and venous drainage from the right atrium. Systemic cooling was then started. When the rectal temperature reached 25°C, circulatory arrest was induced, and SCP was started through the innominate and the left common carotid arteries after cannulating the vessels with balloon-tipped catheters. The flow rate for SCP was 10 mL · kg–1
· min–1. Then the distal aortic anastomosis was performed with a four-branched aortic arch graft (Hemashield, Meadox Medical, Oakland, NJ). After the completion of this anastomosis, the circulation was restarted with perfusion through the side branch of the graft. The reconstruction of left subclavian artery was performed next, and systemic rewarming was started. Then anastomoses of the proximal aorta, innominate artery, and left common carotid artery were performed in that order to complete the arch reconstruction. Electroencephalography is used as the intraoperative neurologic monitor on most occasions. Transcranial Doppler sonography, jugular venous oxygen saturation, and multichannel near-infrared spectroscopy are used to monitor the cerebral blood flow during antegrade SCP. The specific cerebral protection and arch reconstruction techniques required for each individual type of arch vessel anomaly are described below.
Common Brachiocephalic Trunk
First the innominate and the left common carotid arteries were separated from each other and were cannulated separately with balloon-tipped catheters for SCP. This ensured a cerebral protection and arch vessel reconstruction procedure that were, basically, similar to the TAR procedure without arch vessel anomaly. Therefore, this type of anomalous arch vessels did not pose any significant surgical challenge during TAR.
Isolated Left Vertebral Artery
In the cases in which this particular anomaly was discovered intraoperatively, the vessel was simply clamped until the reconstruction of the ILVA was completed. Selective cerebral perfusion with two-vessel perfusion through the innominate artery and left common carotid artery was first used. Then the ILVA reconstruction was performed, after which rewarming was started. In the two cases in which the existence of the ILVA was diagnosed preoperatively with magnetic resonance angiography, direct cannulation and perfusion of the ILVA with an 8F balloon-tipped catheter was undertaken. The ILVA was the dominant arch vessel in these patients and was wide enough for the insertion of the catheter (Fig 2). However, cannulation of the ILVA was not undertaken in the other 2 patients who also had preoperative diagnosis of this vessel because the ILVA in those patients was not the dominant arch vessel. The techniques of ILVA reconstruction are shown in Figure 3. In 7 patients (70%), a side-hole was made on the left subclavian artery graft, and the ILVA was anastomosed to that hole. In 2 patients (20%), a side-hole was made on the native left subclavian artery, to which the ILVA was anastomosed (Fig 3B). In 1 patient (10%), the ILVA was reconstructed with an en-bloc technique (Fig 3C).
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Fig 3. (A) The isolated left vertebral artery (ILVA) is anastomosed to the side-hole of the left subclavian artery (LSCA) graft. (B) The isolated left vertebral artery is anastomosed to the native left subclavian artery. (C) The isolated left vertebral artery and left subclavian artery are reconstructed with en-bloc technique.
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Aberrant Right Subclavian Artery
Selective cerebral perfusion was established with three-vessel perfusion through the right common carotid artery, left common carotid artery, and left subclavian artery. The ARSCA, which originated as the fourth arch branch, was simply clamped. After the proximal descending aorta was circumferentially resected distal to the ARSCA orifice, a distal aortic anastomosis with a four-branched aortic arch graft was performed. The anastomoses of left subclavian artery and proximal aorta were performed next. The right subclavian artery was then exposed and resected on the right side of the trachea and esophagus, after which the right subclavian artery was anastomosed in an end-to-end fashion with another piece of 8-mm graft (Hemashield, Meadox Medical, Oakland, NJ). After completing this anastomosis, right subclavian artery perfusion was started through the graft. After reconstruction of the right common carotid artery and left common carotid artery was completed, the 8-mm graft of the right subclavian artery was anastomosed to the aortic graft as its most proximal branch (Fig 4).
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Fig 4. (Left) Digital subtraction angiogram with schematic after total arch replacement in a patient with aberrant right subclavian artery (ARSCA). (Right) The right subclavian artery (RSCA) was reconstructed on the right side of the trachea and esophagus. (LCCA = left common carotid artery; LSCA = left subclavian artery; RCCA = right common carotid artery.)
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Results
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There were no early or in-hospital deaths in the 21 patients with arch vessel anomalies who underwent TAR. There were no permanent or temporary neurologic complications attributable to the arch vessel anomalies. The extracorporeal circulation data of the 19 patients are as follows: the mean total pump time was 208.3 ± 97.8 minutes; the mean SCP time, 95.6 ± 20.3 minutes; and the circulatory arrest time, 41.9 ± 15.4 minutes. The data were not significantly different from those of the patients having TAR without arch vessel anomalies.
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Comment
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Adachi [1] classified the branching pattern of the aortic arch into seven groups (groups A through G) on the basis of his experience with the dissection of 516 Japanese cadavers. The arch vessel anomalies most frequently encountered were CBT (type B), ILVA (type C), and ARSCA (type G). According to his report, the frequency was 10.9% for CBT, 4.3% for ILVA, and 0.2% for ARSCA [1]. Williams and Edmonds [2] reported their findings about arch vessel anomalies after dissecting 407 human cadavers: 191 American whites and 216 blacks. According to their report, the frequencies of arch vessel anomalies in white and black populations were 17.8% and 37.8% for CBT, 2.6% and 2.0% for ILVA, and 1.0% and 0% for ARSCA, respectively. The above data suggest that the incidence of the CBT variety of arch vessel anomaly might be higher among the black population. Obviously, the finding needs to be validated against larger data sets. Unfortunately, there has been a relative paucity of data in this area of research.
In dealing with the CBT variety, we separated the innominate artery and the left common carotid artery from the common trunk to ensure a more precise arch vessel cannulation for antegrade SCP during arch repair. We were concerned that the insertion of a single cannula in the common trunk might sometimes result in accidental slippage of the cannula into any one of the branches, resulting in inadequate perfusion in the other. Another reason behind the separation of the two vessels was that we wanted to perform the anastomosis at a site that was free from atherosclerotic changes. The short common trunk as well as the bifurcation often has such atherosclerotic changes. Separation of the two vessels was easily accomplished, and, thereafter, no special device or strategy was necessary for cerebral protection and arch reconstruction. Among all types of arch vessel anomalies, the ILVA is the most difficult to diagnose preoperatively. Therefore, they are most often discovered intraoperatively. In the present study, only 4 of the 9 patients (40%) with ILVA could be diagnosed preoperatively. The ILVA is usually a small vessel and is often obscured by other larger arch branches, making its preoperative detection considerably more difficult. Of the 4 patients in whom a preoperative diagnosis was possible, 3 had their diagnosis made with the help of magnetic resonance angiography and 1 with three-dimensional computed tomographic scan. In our experience, magnetic resonance angiography and three-dimensional computed tomographic scan were very useful in the diagnosis of ILVA and in interpreting the dominance of vertebral arteries. However, as ILVA is usually revealed intraoperatively, it is necessary to take special precaution while the arch branches are dissected and exposed. It is difficult to insert the perfusion catheter into the ILVA because of its small diameter. Therefore, in most cases, the vessel has to be simply clamped. However, this entails the risk of neurologic deficit owing to poor perfusion to the brainstem or cerebellum if the arterial communication at the circle of Willis is inadequate. Thus, it is important that the systemic temperature is sufficiently lowered. When the ILVA was discovered intraoperatively, we reasoned that the ILVA should be reconstructed rather than sacrificed because the dominance of the vertebral artery was unknown. The reconstructive procedures of the ILVA are shown in Figure 3. Although anastomosis with the native left subclavian artery as depicted in Figure 3B is the most advantageous from the viewpoint of long-term patency, this requires wide exposure of the left subclavian artery and anastomosis at a very deep position. When the origin of the ILVA is close to the left subclavian artery, the en-bloc technique as shown in Figure 3C is easy and useful. However, severe atherosclerotic changes are usually present at this site, and the ILVA or the left subclavian artery is often involved in aneurysmal dilatation of the aorta. As a result, the en-bloc technique, despite its advantages, cannot be used in most patients with ILVA, even when the latter originates near the left subclavian artery. The technique of left subclavian artery anastomosis shown in Figure 3A may, therefore, be the easiest and most useful.
It is not difficult to diagnose ARSCA preoperatively. With our cerebral protection method, the bilateral common carotid arteries and left vertebral artery were perfused under hypothermia. Although this proved sufficient in avoiding neurologic complications, additional ARSCA perfusion might be needed if the right vertebral artery is found to be dominant on preoperative magnetic resonance angiography. Even when the aneurysmal change does not extend to the orifice of the ARSCA, or the ARSCA itself does not expand to form an aneurysm, distal aortic anastomosis should be performed distal to the ARSCA orifice, and the right subclavian artery should be reconstructed distal to its intersection with the trachea and esophagus. This will circumvent the possibility of aneurysmal dilatation of the orifice of this vessel as well as the vessel itself in the future and prevent tracheoesophageal compression symptoms. In fact, the patients with ARSCA in our series did have aneurysmal dilatation of the ARSCA orifice with degenerative changes in the artery itself. Others have also reported similar findings [5, 6].
In conclusion, surgical treatment of anomalous arch vessels can be accomplished with a satisfactory outcome if a precise preoperative diagnosis can be established. Magnetic resonance angiography and three-dimensional computed tomographic scan may be useful tools for diagnosing arch vessel anomalies, particularly the ILVA variety. When TAR is performed in patients with arch vessel anomalies, it is important to select the most appropriate method for cerebral protection and arch vessel reconstruction. As the ILVA is often revealed intraoperatively, careful manipulation of the arch branches and adequate systemic cooling during SCP are very important for avoiding neurologic complications.
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References
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- Adachi B. Das Arteriensystem der Japaner Verlag der Kaiserl Jap Univ, Kyoto 1928;1:29-31.
- Williams GD, Edmonds HW. Variations in the arrangement of the branches arising from the aortic arch in American whites and Negroes Anat Rec 1935;62:139-146.
- Eusanio MD, Schepens MA, Morshuis WJ, et al. Separate grafts or en bloc anastomosis for arch vessels reimplantation to the aortic arch Ann Thorac Surg 2004;77:2021-2028.[Abstract/Free Full Text]
- Kazui T, Wshiyama N, Bashar AHM, et al. Total arch replacement using aortic arch branched grafts with the aid of antegrade selective cerebral perfusion Ann Thorac Surg 2000;70:3-9.[Abstract/Free Full Text]
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Top
Abstract
Introduction
