Ann Thorac Surg 2001;72:S1065-S1068
© 2001 The Society of Thoracic Surgeons
Supplement: Cardiothoracic techniques and technologies
Multicenter experience with the remote access perfusion (RAP) catheter
Guido J. Van Nooten, MD, PhDa
a Heart Centre, University Hospital Ghent, Ghent, Belgium
Address reprint requests to Dr Van Nooten, Cardiac Surgery Department, University Hospital Ghent, De Pintelaan, 185, 9000 Ghent, Belgium
e-mail: guido.vannooten{at}rug.ac.be
Presented at the Seventh Annual Cardiothoracic Techniques and Technologies Meeting 2001, New Orleans, LA, Jan 24–27, 2001.
 |
Abstract
|
|---|
Background. Cardiac operation has rapidly evolved toward less invasive procedures. Total body perfusion from femoral or iliac vessels combined with endovascular aortic clamping can be achieved using the remote access perfusion (RAP) catheter without opening the sternum. The results of all reported RAP procedures were reviewed.
Methods. A US Food and Drug Administration/CE (Communaté Europeene) multicenter and postmark surveillance information survey from January 1999 to June 2000 evaluated 63 patients undergoing RAP procedures. The series includes coronary artery bypass grafting (46%), mitral valve operation (34%), and combined (3%) and miscellaneous procedures (17%).
Results. Since optimization of the catheter shape, easy placement was obtained during most procedures (74%). Only one procedure had to be converted to a standard approach. However, no dissection or perforation was reported. Perfusion yielded excellent flow characteristics of the RAP catheter predicted by in vitro studies. Continuous transesophageal echocardiography confirmed the stability of the endovascular balloon clamp (93%), most likely related to the near cylindrical balloon shape. In four cases an additional external cross-clamp was applied. The one reported hospital death (1.5%) was nonprocedural related. No strokes were recorded. Peripheral vascular morbidity (8%) was higher during the early period but nearly disappeared after adaptation of the catheter shape.
Conclusions. This multicenter study demonstrated the safety of the RAP technique. Excellent flow characteristics and balloon stability were obtained by improved technology. Indications will be extended in the future because of the device’s enhanced safety and feasibility.
|
Introduction
|
|---|
Cardiac operation has continuously evolved toward less invasive procedures. Alternative approaches for cardiopulmonary perfusion and cardiac arrest were developed recently to avoid direct cannulation, extensive dissection, or external clamping of the ascending aorta [1]. These developments will ultimately lead to totally endoscopic operation [2]. Total body perfusion from femoral or iliac vessels combined with endovascular aortic clamping can be achieved using the remote access perfusion (RAP) catheter (Estech Inc, Danville, CA).
The Estech arterial RAP cannula is a disposable, 81-cm long, flexible polyurethane tube with three lumens with an inflatable polyurethane balloon at the distal end of the cannula. The inflatable balloon has elastomeric properties designed to provide aortic occlusion in a range of aorta sizes with internal diameters from 22 to 34 mm. The outside diameter of the cannula is 21F (7 mm). The cannula has a central lumen for the delivery of arterial blood through multiple distal outlets, a lumen that communicates with the aorta in the area of the aortic root for delivery of cardioplegia solution and left ventricle venting, and a small lumen for control of the distal balloon. The radio-opaque arch segment of the cannula and insertion depth marks aid in positioning the device (Fig 1). In the initial design, the external balloon added a few millimeters of excessive collar to the external diameter at the tip of the catheter. The second design incorporated the balloon into the shaft and reduced the cannula to a true 21F outside diameter catheter as used in the postmark surveillance survey.
View larger version (20K):
[in this window]
[in a new window]
|
Fig 1. Schematic representation of the remote access perfusion catheter. 1 = Port for monitoring cardioplegia—aortic root pressure; 2 = port of attachment of cardioplegia—vent line; 3 = hemostatic valve; 4 = label "k" indicating aortic root lumen; 5 = obturator and seal, attached to arterial perfusion lumen; 6 = Luer port, which provides access to arterial blood; 7 = 3/8 tubing section—area for clamping; 8 = port for attachment of balloon inflation syringe; 9 = port for monitoring balloon inflation pressure; 10 = label "B" indicating balloon inflation lumen; 11 = indicator markings: black line indicates port location, numerals indicate distance from tip in centimeters; 12 = arterial blood outlet ports; 13 = occlusion balloon (inflated); 14 = outlet of aortic root lumen; 15 = radio-opaque aortic arch segment.
|
|
|
Patients and methods
|
|---|
In a US Food and Drug Administration (FDA)/CE multicenter and postmark information survey from January 1999 to June 2000, 63 patients were retrospectively evaluated having undergone the RAP procedure. The participating centers and the number of procedures enrolled in the trial for CE marking/FDA approval and clinical postmark survey are listed alphabetically in Tables 1 and 2. The operations in this series comprised coronary artery bypass grafting (CABG, 46%), mitral valve operation (34%), combined procedures (3%), and miscellaneous operations such as closure of atrial septal defect, paravalvular leakage and myxomectomy in 17%. Mean age at operation was low at 59.3 ± 11.5 years (range 34 to 77 years). The group (45 men and 18 women) had an average body surface area of 1.88 ± 0.21 m2 (range 1.60 to 2.17 m2). The average preoperative New York Heart Association (NYHA) functional class was 3.2. Eighteen percent were redo patients having already undergone CABG (average years after CABG = 5.7 years), whereas 2 patients had previous mitral valve operation and 1 presented a paravalvular leakage after mitral valve replacement. Operations for the study subjects were performed at centers that participated in the regulatory clinical trials and centers that performed the RAP procedure after regulatory approval. All of the centers that participated in the clinical trial for CE marking and the FDA approval obtained Ethics Committee approval and patient consents, and signed an agreement confirming to the FDA that they had no conflict of interest or financial interest in Estech. All of the operations carried out for CE marking and the FDA clinical trial were performed in Europe and South Africa. After the CE mark was approved and the FDA approved the marketing of the device in the United States, Estech allowed the hospitals to decide on an individual basis whether or not the Institutional Review Board approval (the United States’ equivalent of the Ethics Committee) was required. Some hospitals in Europe still did obtain Ethics Committee approval, although this was no longer a requirement. The implanting surgeon chose which procedure to use after consulting the patient.
Operative technique
The approach depended on the procedure, as mentioned by other authors [3]. Standard sternotomy was used in 77% of cases. In 23% an anterior thoracotomy at the fourth or fifth intercostal space (length 12 to 22 cm) was preferred mainly for operation at the level of the left atrium. Meanwhile, peripheral cardiopulmonary bypass was installed at left or right inguinal level in all cases. The RAP femoral 21F aortic balloon catheter was guided into the ascending aorta under echographic control and placed at approximately 2.5 cm of the aortic valve, retrograde, coming from femoral level. The aortic valve was not crossed. Sixty patients underwent the full procedure. In 1 patient the RAP cannula could not be used properly because of severe arteriosclerosis of the descending aorta. In 2 patients, perfusion and endovascular cross-clamping was considered inadequate by the surgeon; thus the procedure was abandoned and converted to a standard operation. Myocardial protection was accomplished with mild to moderate (25° to 32°C) systemic hypothermia. Cardiac arrest was obtained by anterograde crystalloid or blood cardioplegia delivered at the tip of the catheter after complete inflation of the endoclamp. Echo(cardio)graphy by a multiplane (ex. Sonos 2500, Hewlett-Packard Inc, Andover, MA) transesophageal probe and direct pressure monitoring helped guide the procedure. Visualization of the left atrium was enhanced by endoscopy [4].
Statistical analysis
Continuous variables were expressed as mean and standard deviations. A Fisher exact test was used for nonparametric data. Variables entered into the risk-factor analysis for survival, low cardiac output, balloon instability, vascular injury, and stroke included age, sex, body mass index (BMI = weight/length2), presence or absence of redo operation, preoperative NYHA functional class, first or second design 21F catheter placement, presence or absence of associated procedures, balloon inflation volume, aortic clamp time, and extracorporeal circulation (ECC) time. Ideally, a multivariate analysis of variance would be used to compare different groups, but in this study none of the assumptions of such an analysis (normal distribution, homogeneity of variance, etc) were met. If applicable, the nonparametric statistics equivalent of the analysis of variance (Kruskal–Wallis test) was used instead. The level of significance was set at p less than 0.05.
|
Results
|
|---|
The series of fully completed procedures comprises 29 CABG procedures and 21 mitral valve operations (13 mitral valve replacements and 8 valve reconstructions), 1 combined procedure, 7 closures of atrial septal defect-type secundum, 1 tumorectomy, and a closure of a partial dehiscence of a mitral valve prosthesis for paravalvular leakage. Eighteen percent were redo operations. Operative technical data are listed in Table 3. Endoclamping was performed by instillation of 14 to 48 mL saline solution in the balloon (average 30.8 ± 9.1 mL). In 4 patients balloon inflation was considered not occlusive and an additional external clamp was applied (for those cases mean balloon volume = 23 mL). Cardiac arrest was obtained by means of anterograde crystalloid or blood cardioplegia delivered at the tip of the catheter. However, in some redo operations, by not clamping the patent left internal mammary artery (LIMA) graft, cardiac activity restarted prematurely. Thus, further myocardial protection was mandatory at moderate hypothermia of 25°C by additional doses of cardioplegia. Mean aortic clamp time was 56.6 minutes (comparable to standard techniques). De-airing in cases of mitral procedures by thoracotomy remained problematic because of inaccessibility of the ventricles and could be achieved only by suction at the tip of the endoclamp. The mean ECC time of 96.7 minutes was prolonged because of longer reperfusion times in some complex redo operations before obtaining stable hemodynamics. However, only 1 patient needed postoperative inotropic support.
Mortality
Only one hospital death was recorded. This death was nonprocedural related, occurring after late postoperative intestinal infarction (61 days postoperatively) and subsequent multiple organ failure.
Morbidity
Initially there was a high incidence of peripheral vascular injury (intima tears) to the femoral or inguinal vessels in the early phase before introduction of the second-generation true 21F tip catheter (four of five peripheral vascular injuries occurred in the first-design group). Especially harmful to the intima at introduction was the redundant balloon collar, which added a few millimeters to the outside diameter at the tip of the first design catheter. In 3 patients positioning of the balloon was considered instable (in 1 the balloon ruptured). Another balloon puncture occurred but the device could be easily replaced before definitive clamping. Cardioplegia delivery necessitated high line pressures; however, only twice was the pressure considered inadequate. Although the RAP technique was feasible in arteriosclerotic patients, 1 patient had to be converted to a standard resternotomy because of a plaque dislocation in an extremely calcified descending aorta. Another patient had to undergo placement of an intraaortic balloon pump for postoperative low cardiac output; the operation for a third patient was revised because of bleeding. No dissection occurred in the entire series. No neurologic deficits were noticed clinically once extubated in ICU.
Subjective impression
In an FDA clinical investigation on 22 patients the surgeon’s opinion was recorded on balloon stability, cardioplegia delivery, and root venting and expressed in number of cases as listed in Table 4.
Statistics
Statistical analysis reported female sex (p < 0.001) and first-generation catheter (p = 0.04) as independent risk factors for vascular injury. The sole risk factor for balloon instability was an inflation volume of less than 25 mL (p < 0.01). All other variables were not significant.
|
Comment
|
|---|
The RAP technique was explored in 63 patients (of whom 60 underwent the whole procedure) as an alternative approach for total body perfusion and endovascular clamping [3]. Although the RAP catheter does not involve a thorough port-access operation, transesophageal echocardiography and videoscopy are important aiding tools to control the procedure [5]. The early results were encouraging even in some preoperatively severely disabled patients (average NYHA functional class 3.2) such as redo CABG patients (18% of total series). The study group comprised more men than women and patients with a mean body surface area of 1.88 m2, because the technique necessitates larger femoral arteries (and thus larger patients) for easy cannulation. Before the improvement toward a true 21F catheter, some intimal injuries were inflicted by collar protrusion of the deflated balloon. Since adjustment, those peripheral injuries were rare. Although using a RAP catheter was feasible in arteriosclerotic patients, 1 patient had to be converted to a standard resternotomy because of plaque dislocation in an extremely calcified descending aorta.
Smooth retrograde flow perfectly matched to the patient size was obtained with excellent perfusion through the numerous side holes of the catheter. The aortic endoclamp allowed the surgeons to operate successfully on some patients needing difficult redo-mitral (post-CABG) procedures without reopening the sternum. Once the RAP catheter was positioned at the correct level in the ascending aorta, endoclamping was performed by instillation of (enough) saline solution in the balloon. Balloon stability was considered highly satisfactory even during cardioplegia delivery. Cardiac arrest was obtained by means of anterograde cardioplegia delivered at the tip of the catheter sometimes under high line pressures. In 4 patients an additional external clamp was mandatory, in some cases because of incomplete balloon inflation.
Avoidance of damage to the open bypass grafts (particularly the left internal mammary graft or LIMA) remains the key issue in redo operations. However, by not clamping the LIMA graft, myocardial protection was sometimes suboptimal necessitating additional doses of cardioplegia and deeper cooling. Mean aortic clamp times were comparable to standard procedures. Aortic root venting was not always optimal. De-airing for open procedures remained a problem because of inaccessibility of the ventricles. Removal of air can be obtained only by suction at the tip of the catheter at the cost of high negative line pressures. Mean ECC time was prolonged probably because of initial hemodynamic instability during reperfusion in complex cases. Only 1 patient needed prolonged postoperative support with inotropic agents. No dissection or perforation occurred in the entire series.
The excellent results in this patient group are a step toward the realization of totally endoscopic techniques in cardiac operations. In the future this procedure could be combined with computer-assisted techniques [6].
|
References
|
|---|
-
Mohr F.W., Falk V., Diegeler A., Walther T., van Son J., Autsschbach R. Minimally invasive port-access mitral valve surgery. J Thorac Cardiovasc Surg 1998;115:567-574.[Abstract/Free Full Text]
-
Falk V., Diegeler A., Walther T., et al. Total endoscopic off-pump coronary artery bypass grafting. Eur J Cardiothorac Surg 2000;17:38-45.[Abstract/Free Full Text]
-
Tabry I. Left-sided Heartport approach for combined mitral and coronary bypass surgery. Heart Surg Forum 2000;3:334-336.[Medline]
-
Chitwood W.R., Elbeery J.R., Chapmann W.H.H., et al. Video-assisted minimally invasive mitral valve surgery: the "micro-mitral" operation. J Thorac Cardiovasc Surg 1997;113:413-414.[Free Full Text]
-
Ribakove G.H., Miller J.S., Anderson R.V., et al. Minimally invasive port-access coronary artery bypass grafting with early angiographic follow-up: initial clinical experience. J Thorac Cardiovasc Surg 1998;115:1101-1110.[Abstract/Free Full Text]
-
Reichenspurner H., Damiano R.J., Mack M., et al. Use of the voice-controlled and computer-assisted surgical system Zeus for endoscopic coronary artery bypass grafting. J Thorac Cardiovasc Surgery 1999;118:11-16.[Abstract/Free Full Text]
Top
Abstract
Introduction
