Ann Thorac Surg 2005;80:1303-1308
© 2005 The Society of Thoracic Surgeons
Original article: Cardiovascular
Endovascular Aortic Clamping for Pseudoaneurysms of the Aortic Root With Aortic Regurgitation
Daniele Maselli, MD
*
,
Gianluca Santise, MD,
Andrea Montalto, MD,
Francesco Musumeci, MD
Department of Cardiac Surgery, San Camillo Hospital, Rome, Italy
Accepted for publication February 1, 2005.
* Address reprint requests to Dr Maselli, U.O. Cardiochirurgia, Azienda Ospedaliera Pisana, Via Paradisa No 2, 56124 Pisa, Italy (Email: dmaselli{at}tiscali.it).
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Abstract
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BACKGROUND: We propose a safer strategy for surgical treatment of retro-sternal pseudoaneurysms of the aortic root with severe aortic regurgitation. The objective was to allow safer re-entry in a quite and bloodless field eliminating the risk of ventricular distension and avoiding deep hypothermia.
METHODS: In 6 patients presenting with postsurgical aortic root pseudoaneurysms in close proximity to the sternum associated with aortic regurgitation, we used the following techniques: femorofemoral cardiopulmonary bypass; transfemoral aortic endoclamping; percutaneous retrograde cardioplegia administration before sternotomy in patients with normal descending aorta; femoroaxillary cardiopulmonary bypass; transaxillary aortic endoclamping; percutaneous retrograde cardioplegia administration before sternotomy in patients with concomitant disease of the descending aorta.
RESULTS: All patients survived the operation and were discharged home. Arterial cannulation and endoclamp insertion were uneventful. Reentry was uncomplicated. Deep hypothermia was avoided in all cases. No occurrences of even minor neurologic problems were observed. None of these patients experienced a postoperative low cardiac output syndrome. Postoperative course was complicated in 1 patient with re-entry for bleeding; acute renal insufficiency requiring hemofiltration in 2 patients; pneumonia in 1 patient; and soft tissues sternotomy infection in 1 patient.
CONCLUSIONS: In patients presenting with a pseudoaneurysm of the aortic root attached to the sternum and concomitant aortic regurgitation it is possible, by closed chest endovascular aortic clamping, to eliminate risks of ventricular distension and to avoid deep hypothermia.
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Introduction
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Surgery can be very difficult and challenging in situations in which a retro-sternal pseudoaneurysm of the aortic root is associated with significant aortic regurgitation and diseased descending aorta. The risk of entering the pseudoaneurysm during sternotomy is very high. Peripheral cardiopulmonary bypass (CPB) via femoral vessels has been used [1] to achieve hypothermic circulatory arrest before sternotomy to expose and control a clampable segment of the ascending aorta in a bloodless field. Transfemoral arterial return however, due to the high risk of brain damage secondary to retrograde emboli or to malperfusion, can be dangerous in patients with atheromatous or dissected descending aorta [2, 3]. Moreover, in patients with significant aortic regurgitation, closed chest hypothermic circulatory arrest expose to a risk of left ventricular dysfunction due to over-stretching of myocardial fibres that occurs during the time period included between onset of ventricular fibrillation and circulatory arrest.
We propose a surgical strategy based on aortic endoclamping, which allows a safe approach to postsurgical retro-sternal pseudoaneurysms of the aortic root associated with severe aortic regurgitation, avoiding closed chest hypothermic circulatory arrest. We propose the following configurations: femorofemoral CPB, transfemoral aortic endoclamping, percutaneous retrograde cardioplegia administration before sternotomy in patients with normal descending aorta; femoroaxillary CPB, transaxillary aortic endoclamping, percutaneous retrograde cardioplegia administration before sternotomy in patients with concomitant disease of the descending aorta. We report observed anatomical varieties and techniques adopted for surgical approach.
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Material and Methods
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From September 1, 1998 until September 1, 2003, 440 patients (315 male, age 60.7 ± 13.2 years), underwent aortic root replacement or ascending aorta replacement at our institution. Fifty-five were redo operations (46 male, age 55 ± 14.1 years), 6 of these were post-surgical retro-sternal pseudoaneurysm of the aortic root or ascending aorta associated with significant aortic regurgitation. In this group of patients we identified for tactical reasons two conditions: type 1, presence of an endoclampable native or synthetic segment of the ascending aorta with normal descending aorta (Fig 1); and type 2, presence of an endoclampable native or synthetic segment of the ascending aorta with diseased descending aorta (Fig 2).
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Fig 2. Type 2. An endoclampable segment of the ascending aorta is present, descending aorta is diseased.
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An operative strategy was defined for each of these types of aortic pathology in order to achieve closed chest CPB and cardioplegic cardiac arrest.
Surgical Technique
Both radial arteries were cannulated for arterial pressure monitoring. Transesophageal echocardiography (TEE) was used for guiding intracardiac percutaneous catheters positioning and to scan descending aorta for presence of atheromatous disease. Before starting the procedure, under TEE guidance, an Endo-Plege catheter (Heartport, Redwood City, CA) was placed via the right internal jugular vein for retrograde cardioplegia delivery. All patients were draped with groins and subclavear regions exposed.
In type 1 lesions (endoclampable ascending aorta and normal descending aorta) femorofemoral CPB was instituted. Right femoral artery and vein were exposed through a small (3 cm) incision in the groin. After heparin administration venous (Quickdraw venous cannula; Heartport) and arterial (Endo Return arterial cannula; Heartport) cannula were inserted through a 5-0 polypropilene purse-stringe suture using the Seldinger technique. The venous cannula was advanced under TEE control up to the mid-portion of the right atrium. The arterial cannula was positioned in the common femoral artery. The Y branch of the arterial cannula was used to position the Endo-clamp (Endo-clamp; Heartport) into the ascending aorta. Before sternotomy, after incision of pre-sternal layers and removal of steel wires, CPB with vacuum assisted venous drainage and cooling were started. When the temperature of 32°C was reached the Endo-clamp was inflated under TEE control. Immediately after Endo-clamp inflation, in order to avoid its displacement, cardiac arrest was induced by administration, into the aortic root, of a bolus of adenosine (6 mg/mL, 4 mL). Retrograde intermittent warm blood cardioplegia was started with contemporary venting of the aortic root in order to avoid ventricular distension. Once the heart was arrested, sternotomy was performed and the prosthesis used to replace the ascending aorta was isolated and clamped with a conventional cross-clamp while the Endo-clamp was deflated and withdrawn into the aortic arch. Aortic root was replaced while the patient was cooled down to 24 to 28°C. After replacing the root circulation was arrested to perform arch anastomosis. Our policy was to remove all synthetic tissues used in the previous operation to minimize the risk of re-infection. The new conduit was sewed to the aortic arch resecting all its ventral portion. After a short period of retrograde wash out cerebral perfusion through the superior vena cava, circulation and rewarming were restarted. Before tying the distal suture the endo-clamp was re-advanced into the ascending aorta to allow air venting during weaning from CPB. The procedure was completed in the usual fashion. Continuity of femoral vessels was re-established, after cannula removal, by tying purse-string sutures.
In type 2 lesions (endoclampable ascending aorta and diseased descending aorta) right femoral vein-right axillary artery CPB was instituted. After heparin administration, the right atrium was percutaneously cannulated via the right femoral vein under TEE control by a 25 Fr QuickDraw venous cannula (Heartport). The right axillary artery was exposed. An 8- or 10-mm Dacron graft, trimmed at 45-degree angle to get a bigger surface for an easier advancement and withdrawal of the endoaortic balloon, was anastomosed to the ventral aspect of the axillary artery by continuous 6-0 polypropilene suture. A 23 Fr EndoReturn arterial cannula (Heartport) was inserted into the Dacron graft, secured with ties, and connected to the arterial line. A guidewire was advanced under echo guidance into the side branch of the arterial cannula, the Dacron graft and the axillary artery, down to the ascending aorta. An Endo-clamp aortic catheter (Heartport) was then advanced through the same route and positioned at the level of the ascending aortic endo-clampable segment. Before sternotomy, after incision of pre-sternal layers and removal of steel wires, CPB with vacuum assisted venous drainage and cooling were started. When the temperature of 32°C was reached the Endo-clamp was inflated under TEE control. Immediately after Endo-clamp inflation, in order to avoid its displacement, cardiac arrest was induced by administration, into the aortic root, of a bolus of adenosine (6 mg/mL, 4 mL). Retrograde intermittent warm blood cardioplegia was started with contemporary venting of the aortic root in order to avoid ventricular distension. Once the heart was arrested sternotomy was performed and the prosthesis used to replace the ascending aorta was isolated and clamped with a conventional cross-clamp while the endo-clamp was deflated and withdrawn into the aortic arch. Aortic root was replaced while the patient was cooled down to 24 to 28°C. After replacing the root circulation was arrested to perform arch anastomosis. The new conduit was anastomosed to the aortic arch resecting all its ventral portion. After a short period of retrograde wash out cerebral perfusion through the superior vena cava, circulation and rewarming were restarted. Before tying the distal suture the Endo-clamp was re-advanced into the ascending aorta to allow air venting during weaning from CPB. The procedure was completed in the usual fashion. The Dacron graft used for axillary artery cannulation was tied and divided.
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Results
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All patients survived the operation and were discharged home, all of them are alive and well at the last follow-up visit, no recurrences are reported. Patient population and operative data are synthetically reported in Tables 1 and 2,
respectively, for type 1 and type 2 patients. Each table focuses on reason and kind of first operation, time delay to redo operation, reason and kind of second operation. Location of entry port of the pseudoaneurysm and mechanism of aortic regurgitation are reported in the Tables 1 and 2, whereas lesions observed in type 1 and type 2 patients are illustrated, respectively, in Figures 3 and 4. 
Arterial cannulation and Endo-clamp insertion were uneventful. In type 1 mean time from endoclamping to conventional cross-clamping was 9.3 ± 0.57 minutes, mean total cross-clamp time was 84 ± 8.7 minutes, mean circulatory arrest time was 11.6 ± 0.57 minutes. In type 2 mean time from endoclamping to conventional cross-clamping was 11.3 ± 2.0 minutes, mean total cross-clamp time was 80.6 ± 9.0, mean circulatory arrest time was 13.6 ± 1.15 minutes. Mean intensive care unit stay was 124 ± 118 hours (48 ÷ 360) and mean in hospital stay was 13.3 ± 6.0 days (10 ÷ 25). The following complications were observed: bleeding requiring one re-entry and a mean per patient consumption of 5.3 ± 3.0 (2 ÷10) units of packed red blood cells, 4 ± 3.0 (0 ÷6) units of fresh frozen plasma and 2 ± 3.0 (0 ÷6) units of platelets; acute renal insufficiency requiring CVVHF in 2 patients; pneumonia (pseudomonas aeruginosa) in 1 patient; and superficial surgical site infection (sternotomy) in 1 patient. No occurrences of even minor neurological problems were observed. None of these patients experienced a postoperative low cardiac output syndrome.
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Comment
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In order to minimize the risk of catastrophic exsanguination and brain damage, pseudoaneurysms of the ascending aorta/aortic root are usually approached under hypothermic circulatory arrest. Femorofemoral or femoral vein to axillary artery cannulation is used to start CPB and cooling before sternotomy. Closed chest circulatory arrest however, can be very dangerous in the presence of severe aortic regurgitation as, before stopping circulation, continuous flow in the fibrillating heart can cause left ventricular distension. Methods to decompress the left atrium or left ventricle from the left chest require an added thoracotomy and can be ineffective in preventing ventricular distension if the regurgitant volume is very high. Ascending aortic cross-clamping through a minimal right thoracotomy can be dangerous in presence of a pseudoaneurysm.
A technique of aortic endoclamping based on the port-access technique [4, 5] for control of ascending aortic pseudoaneurysms has been reported by D'Attelis [6] and by Pettersson [7] and has proven to be reliable and safe. The Endo-clamp can be used to exclude from the circulation the pseudoaneurysm and stop the heart by contemporary retrograde cardioplegia administration. Sternotomy can be performed and the native or synthetic aorta can be controlled and cross-clamped in a quite and bloodless field with no risk of exsanguination and brain or myocardial damage. This can be easily accomplished, by surgeons trained in port-access techniques, through the femoral route in type I patients in which risk of retrograde emboli is low due to the presence of a normal descending aorta. Even in absence of aortic regurgitation, as in the presence of a functioning aortic prosthesis, the technique can be advantageous to stop the heart before opening the chest whenever the risk of entering the pseudoaneurysm exists. Case two of type I group (Fig 3) is an example of this condition.
Type 2 patients with dissected or atherosclerotic or dilated descending aorta, have to be approached through axillary route. In a previous report [8] we described the first application of aortic endoclamping combined with antegrade perfusion through the axillary artery in a patient with ascending aortic pseudoaneurysm and severe aortic regurgitation combined with dissected descending aorta. That case is included in this report (case 1, Table 2). We emphasized the advantages of this technique that allows: antegrade flow into the aorta, maintained perfusion of the right upper limb during cardiopulmonary bypass, closed chest clamping of the ascending aorta, and avoidance of the deleterious affects of aortic regurgitation, administration of cardioplegia and left ventricular venting before sternotomy.
Several limits exists to the widespread application of this technique which in our opinion has to be selected only for very special cases in which at the same time close proximity of the pseudoaneurysm to the sternum and significant aortic regurgitation are observed.
First, before planning the procedure it has to be documented, that the brachiocephalic trunk and axillary artery are not involved in the disease. For this study this was completed with an echo-Doppler study or computed tomographic scan. It has been documented [9] that axillary route is excellent for arterial return during CPB but it can be very dangerous in presence of vessel stenosys. In patients with a previous dissection it can be not comfortable to "navigate" with catheter through the axillary artery, it has to be observed however that in such patients the artery is much bigger than usual and, at least in our experience, its involvement in dissection is uncommon.
Second, good experience with standard port-access surgical and monitoring procedures is obviously essential. Positioning of the percutaneous retrograde cardioplegia catheter is difficult, time consuming, and requires proper training. Direct continuous active monitoring of the endo-clamp position by transoesophageal echocardiography or indirect monitoring of eventual endo-clamp displacement by continuous analysis of the right radial artery pressure curve is crucial to prevent low cerebral blood flow when the balloon is inflated. As preoperative monitoring and catheter positioning is very time consuming, we don't consider using this technique in emergency situation but only in elective cases.
Third, an endoclampable aortic segment may not be available. Absence of an endo-clampable segment can be due to a position of the entry port of the pseudoaneurysm too high and close to the brachiocephalic trunk, in this case the risk of occluding it during endo-clamp inflation should be a serious discouragement to use this technique even if monitoring techniques allow a prompt recognition of this problem [10]. Absence of an endoclampable segment can also be due to dimensions of the ascending aorta exceeding 40 mm, which is the maximum clampable size with currently available balloons. In the design of this study we originally defined as type 3 patient in which an endoclampable segment is not available with normal or diseased descending aorta. In these patients the endoclamp can be theoretically used as a transvalvular aortic vent through the femoral or axillary artery route. However the maximal amount of blood that can be vented through an endoclamp can be inadequate to face the amount of the regurgitant volume through the aortic valve. We never faced a situation in which this option could be used.
Fourth, costs are increased but, in our opinion, can be counterbalanced by the big advantage that the technique offers. It can be argued that our technique carries the disadvantage of an added myocardial ischemic time from closed chest endo-clamping to traditional cross clamping. In our experience access and control of the ascending aorta was always easy because the pseudo-aneurysm cavity works as a guide to the synthetic aorta, this time ranged from 9 to 13 minutes. With conventional techniques the same time is needed to control the aorta while the brain is not perfused and after a period of left ventricular distension.
Aortic endoclamping for pseudoaneurysm control can be very helpful in eliminating or reducing some of the management problem of a cohort of patients that, as can be observed by our results and complication rate, even without major intraoperative adverse events, is exposed to a very complex postoperative course. Avoiding the risk of a massive haemorrhage or severe hypotension or postoperative low cardiac output may have played a major role in keeping these patients alive.
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References
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Abstract
Introduction
