|Home | About | Journals | Submit | Contact Us | Français|
The Seldinger technique is a method of femoral cannulation that has been used to establish cardiopulmonary bypass. Reports of cannulation of the ascending aorta for antegrade perfusion using the Seldinger method are anecdotal. To the best of our knowledge, the approach described herein for direct cannulation of the ascending aorta with use of the Seldinger technique for antegrade perfusion has not been previously described in the English-language medical literature. This method is helpful when the surgeon is treating a patient who has a calcified ascending aorta, complicated aortic dissection, calcified femoral vessels, or a diseased thoracoabdominal aorta. In such cases, retrograde perfusion has been associated with severe complications as a result of atheromatous embolization from the descending thoracic aorta.
Herein, we describe our approach to cannulation for cardiopulmonary bypass, which entails insertion of an aortic cannula into the ascending aorta by means of the Seldinger technique. A soft-tip guidewire is inserted through an arterial entry catheter that has been used to puncture a hole in the wall of the vessel. Then the aortic cannula is introduced into the vessel, sliding along the guidewire. Guided by transesophageal echocardiography, the tip of the cannula is positioned carefully and is then advanced into the descending aorta. This positioning of the cannula decreases the chance of arterial embolization, thereby improving cerebral protection. If cannulation of the ascending aorta is not feasible, the transverse aortic arch or proximal descending aorta can be used.
In patients undergoing open-heart operations, perioperative stroke and death can be precipitated by dislodgment of atherosclerotic débris from the aortic wall. These complications can be caused by manipulation of the aorta, cross-clamping, and the “sand-blast” effect of the tip of the cannula in the aortic arch. Positioning the tip of the aortic cannula in the proximal descending aorta is advantageous because it reduces turbulence in the aortic arch, and, consequently, reduces the potential for dislodgment of atherosclerotic emboli.
We present a simple and safe technique for cannulation of patients with a diseased aorta who require coronary, valvular, or aortic surgery. We combine the Seldinger technique with 2 methods for cerebral protection from atheromatous débris—introduction of the cannula into the ascending aorta, and placement of the tip of the cannula in the proximal descending aorta with echocardiographic guidance.
Through a median sternotomy, the aorta is examined for calcification. Transesophageal echocardiography (TEE) and palpation during transient controlled hypotension are used to detect atherosclerotic changes in the aortic wall. Epiaortic ultrasonography is used in selected cases. An area of the ascending aorta that is devoid of major calcification is marked for cannulation. If the ascending aorta is found to have localized atheromas, a suitable site far from their location is chosen, and may include the lower curvature of the transverse arch or the proximal descending aorta.
Two diamond-shaped 4–0 polypropylene sutures are placed at the cannulation site. The aortic adventitia is incised, and an arterial entry catheter is inserted in the direction of the aortic arch. A soft-tip 0.9-mm guidewire is passed through the 19G arterial entry catheter; the catheter is then removed while the wire is kept in place. The position of the wire in the descending aorta is confirmed by TEE. Subsequently, the aortic cannulation site is dilated using 3 tapered Teflon dilators that are provided in a preassembled kit. Bleeding from the cannulation site is easily controlled with the fingertip, and the aortic cannula (Fem-Flex II™, Edwards Lifesciences; Irvine, Calif) (Fig. 1), with the obturator in place, is inserted over the guidewire (Fig. 2). Placement of the cannula in the center of the proximal descending aorta is confirmed by TEE (Fig. 3). The wire and the obturator are removed, and the cannula is secured to the skin, while the intra-aortic portion is kept in the center of the aortic lumen. The cannula is then attached to the arterial line of the heart–lung machine, and the 3/8-inch connector on the arterial cannula is connected to a 3-way stopcock that facilitates de-airing of the cannula before cardiopulmonary bypass is instituted and central aortic pressure is measured.
In selected circumstances, such as a type A aortic dissection, aneurysmal enlargement of the ascending aorta or arch, or a porcelain aorta, the same cannula is used to cannulate the axillary or femoral artery, again by the Seldinger technique. In the aforementioned situations, the use of this small cannula, without cross-clamping distal to the insertion point, avoids compromising the antegrade perfusion of the extremity.
We have used this technique in 301 patients undergoing coronary, valvular, and aortic surgery. The overall postoperative stroke rate has been 2% (6 patients) in a high-risk population. From this group, 4 patients (1.3%) had a permanent stroke.
Percutaneous femoral cannulation for cardiopulmonary bypass was first described for use in patients with refractory cardiac arrest.1 We present a safe approach for the antegrade cannulation of a diseased aorta: a cannula with excellent hemodynamic performance is introduced via the Seldinger technique, and principles of cerebral protection are applied while the tip of the cannula is positioned with TEE guidance.
The described method of aortic cannulation has multiple advantages. The benefit of ascending aortic cannulation is combined with having the tip of the aortic cannula located just distal to the left subclavian artery. Consequently, the turbulence and the sand-blast effect at the tip of the cannula occur in the descending aorta, thereby decreasing the probability of dislodgment of débris into the carotid arteries. Embolization of débris in the descending thoracic aorta is less likely than cerebral embolization to cause morbidity and death. Another benefit of descending aortic perfusion is the reduction of the Coanda effect that can be associated with carotid hypoperfusion in patients undergoing perfusion with a short cannula from the ascending aorta.2 In this situation, the Coanda effect manifests as a jet stream that adheres to the boundary wall, hence lowering the pressure along the opposite wall.
Another advantage of the Fem-Flex II cannula is its small diameter (16F–20F), which requires a relatively small aortotomy that is easily repaired after aortic decannulation. Furthermore, the use of this cannula lowers the possibility of iatrogenic aortic dissection, due to the controlled insertion of the cannula over a guidewire.
Because of its ease of use, the cannula can be inserted in the transverse arch or the proximal descending aorta 'when the distal ascending aorta is not suitable—for example, in reoperations or in cases involving severe calcification of the distal ascending aorta. In patients with a grade IV–V aorta (according to Katz's classification3) or porcelain aorta, different strategies for cannulation are used. Axillary cannulation, total revascularization with Y grafts from mammary arteries, and avoidance of clamping the ascending aorta are among these alternative methods.
Most patients who have a type A aortic dissection undergo hemiarch replacement in our practice. The benefits of axillary cannulation include fewer atherosclerotic changes, antegrade flow to the arch vessels, and a lower infection rate compared with that of femoral cannulation. These patients undergo axillary artery cannulation with an 8-mm Dacron graft that is sutured to the axillary artery. The Fem-Flex arterial cannula is subsequently inserted into the Dacron graft (instead of into the axillary artery), and is secured with a few silk ties around the Dacron graft. This method prevents the arm ischemia that can be associated with direct cannulation of the axillary artery. To avoid pressurization or malperfusion of the aortic false lumen, no clamp is placed on the aorta before deep hypothermic circulatory arrest is accomplished.
In summary, we described a safe and easy technique for the cannulation of a diseased aorta, which should be part of the cardiac surgeon's standard tools. We have yet to observe an adverse outcome in direct association with the use of this cannula. In order to test our observations, a matched case–control study involving this cannulation technique is under way.
The authors wish to acknowledge Rita Laire for her help in preparing the manuscript.
Address for reprints: Ali Khoynezhad, MD, PhD, Section of Thoracic and Cardiovascular Surgery, University of Nebraska Medical Center, 982315 Nebraska Medical Center, Omaha, NE 68198-2315. E-mail: ude.cmnu@dahzenyohka
Dr. Khoynezhad is now at the Division of Thoracic and Cardiovascular Surgery, University of Nebraska Medical Center, Omaha, Nebraska; and Dr. Plestis is at the Department of Cardiothoracic Surgery, Mount Sinai Medical Center, New York, New York.