NEW TECHNIQUES
Use of a modified introducer sheath with a side-hole to improve access to left ventricular veins with proximal origin
Department of Adult Cardiology Prince Sultan Cardiac Center, PO Box 7897 (X-982), Riyadh 11159 Saudi Arabia
Manuscript submitted 4 April 2005. Accepted after revision 21 August 2005.
Corresponding author. Tel: +966 55 561 6245; fax: +966 1 474 9995. E-mail address: avnrt{at}hotmail.com
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Abstract |
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Aims Despite technical advances in tools used to facilitate implantation of cardiac resynchronization therapy (CRT) devices, there are many hurdles related mainly to the variation in the anatomy of the coronary veins. One such difficulty is the presence of a very proximal origin of the lateral or postero-lateral cardiac vein.
Methods and results We describe an alteration of existing left ventricular (LV) lead delivery sheath with the creation of a side-hole 35–50 mm from its tip. This modification is made to provide access to proximal cardiac vein ostia, while maintaining adequate support for the delivery system. The modified introducer sheath was used in the implantation of six CRT systems (four defibrillators and two pacemakers) in patients who had a proximal origin of the lateral or postero-lateral cardiac vein, all of which were successful and without complications.
Conclusion In those patients with unusual proximal origin of target LV veins, modifications of the introducer sheath with the creation of a side-hole facilitate the successful implantation of the LV pacing lead. Until this modified sheath is tested, this technique is considered experimental and may carry unknown risks.
Key Words: Cardiac resynchronization, Biventricular pacing, Implantation tools, Cardiac vein
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Introduction |
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Implantation of biventricular pacing systems for cardiac resynchronization therapy (CRT) has been a revolution in treatment of congestive heart failure.1
,2 However, the major difficulty faced by implanting physicians has been the successful placement of the left ventricular (LV) lead through the coronary sinus into one of the cardiac veins.1–5 There are several barriers to the successful implantation of the LV lead. Wide variation in coronary sinus anatomy, cannulating the coronary sinus ostium, finding an appropriate vein, and finding a secure site with an acceptable pacing threshold are just some of the major obstacles encountered. Several studies have suggested that particular location of the LV lead is of great importance to patients' response to treatment.6–9 It was found that the best position for the LV lead would be the site with the latest activation; quite often this happens to be the basal position of a lateral or a postero-lateral vein. This also appears to be the site associated with better LV systolic performance.10 Review of coronary sinus venograms in over 50 patients at Prince Sultan Cardiac Center demonstrated the extreme variation with regard to the anatomy of the coronary venous system. We noticed that the origin of the lateral cardiac vein, particularly the postero-lateral vein, may lie somewhere between the coronary sinus ostium and a position proximal to the vein itself. In some patients, the target vein opens near or at the coronary sinus ostium (Figure 1) along with the middle cardiac vein. Current tools are sub-optimal in providing the necessary support for the introduction of the pacing lead into a coronary vein that originates near or close to the coronary sinus ostium. Unfortunately, these are the veins which should be targeted for optimal LV lead positioning.
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We report here a technique of modifying existing introducer sheaths to allow access to lateral or postero-lateral veins with very proximal origin by providing adequate coronary sinus access security and guide support.
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Methods |
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Patients were consented and brought to the electrophysiology laboratory in the fasting state. Using available seven French introducer sheaths designed to access the coronary sinus (Attain 6216 and 6218, Medtronic, St Paul, MN, USA), we used a number 11 blade to create a small side-hole, 35–50 mm proximal to the tip of the sheath, depending on patient's LV size (Figure 2). This side-hole was created on the outer side of the normal distal curve with a slight anterior tilt to it (a cross section of the sheath in position in the coronary sinus, this would be at 4–5 o'clock position). The size of the side-hole was sufficient to allow a five French lead to be advanced easily from the catheter and through the side-hole. The hole was elliptical in shape to allow for sidetracking, as opposed to a right angle exit from the sheath.
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50 mm from the tip. It is enough in size to allow the dilator that originally comes with the sheath to pass through.Technique for using this modified catheter
The sheath is introduced into the coronary sinus with the aid of a steerable electrophysiology catheter. After the steerable catheter locates the coronary sinus, the sheath is then advanced over the catheter distally. Initially, the sheath is advanced until the side-hole is at least a centimetre beyond the coronary sinus ostium (Figure 3). The steerable guiding catheter is then removed and occlusion balloon venography is then performed to outline the coronary venous anatomy (Figure 1) and help identify the presence of a vein with proximal origin. After the anatomy is outlined, dye is injected into the guiding sheath. As shown in Figure 3, dye will escape from the catheter through the side-hole, thus allowing one precisely to locate it. The catheter is subsequently steered to bring the side-hole closer to the origin of that vein. This particular sheath allows some rotation so the side-hole may be pointed anteriorly or inferiorly, depending on the angle at which the vein originates. With this configuration, even if the introducer sheath is pulled proximally so that the side-hole is very proximal, at the origin of the coronary sinus, the risk of losing support or access to the coronary sinus is reduced. A J-shaped tip angioplasty (PTCA) wire is used then to exit from the side-hole and cannulate the vein. If the vein cannot be cannulated easily with the angioplasty wire, then a five French right Judkins catheter may be used to exit the sheath from the side-hole and guide the wire into the desired position. An over-the-wire LV pacing lead is then introduced over the wire into the desired location in the coronary vein. The pacing lead may also be advanced using a curved stylet without the aid of the wire as shown in Figure 4. After the optimal location of the lead is achieved, the stylet is pulled a bit but is kept within the intra-coronary sinus part of the lead to provide adequate lead support (Figure 5). We routinely use the stiffer stylet to position and support the LV pacing lead and reduce the potential for dislodgment during sheath removal. Once measurements are ascertained and the final position is decided upon, the introducing sheath is pulled gently, whereas the stiff stylet is still in the LV lead. The sheath may then be removed in total using a slitter (Figure 6). Special care is taken not to damage the lead at the exit point from the side-hole. Minor difficulty may be encountered beyond the point of the side-hole at the pre-pectoral exit wound. This should not be a problem if gentle pull is used, and the lead is watched carefully under fluoroscopy. One method, which we found helpful, was to rotate the lead and the sheath, back and forth, while steadily pulling. Adequate lead slack and maintaining the stylet in the lead are necessary to complete successfully that stage. The pacing lead is then secured.
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Results |
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CRT implantation was attempted in six patients (five men and one woman). All patients had lateral or postero-lateral cardiac veins with very proximal origin. Mean age of this group was 52.1±6.3, and four of them had underlying non-ischaemic cardiomyopathy. One patient had prior coronary bypass surgery, whereas two had mechanical mitral valve replacement. Mean symptom class was 3.4 and the mean ejection fraction was 21±4%. Four CRT-D and two CRT systems were implanted in these patients, all of which were successful and without complications. We resorted to this technique only when we were unsuccessful in accessing true lateral veins (in two patients) or when this postero-lateral vein happens to be the only major vein in the lateral LV. We do not implant LV leads in either the great or middle cardiac veins due to evidence of reduced haemodynamic response.10
Figures 1 and 3–5 are from implant procedures in different patients. The modified sheath greatly facilitated cannulation and final positioning of the LV lead in cardiac veins with proximal ostia. No major or minor complications were observed either intra-procedurally or in the post-operative period.
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Discussion |
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The major problem in trying to introduce a pacing lead into a proximally originating postero-lateral or lateral cardiac vein is lack of adequate guide or introducer sheath support. The distance between the coronary sinus ostium and the lateral right atrial wall is inconsistent in patients with heart failure and seems to depend to an extent on the degree of right heart compromise and severity of tricuspid valve regurgitation. In addition, there is variability among patients with regard to the support from the floor of the right atrium, which can sometimes be minimal in patients who have a small Eustachian ridge or dilated inferior vena cava. This makes adequate support from existing introducer sheaths inconsistent, particularly when cannulating cardiac veins is attempted with the sheath at a proximal coronary sinus position or near the ostium. At times, it might be possible to cannulate such veins proximally but as soon as an attempt is made to advance the LV lead into the vein, the guiding sheath is pushed out and access to the coronary sinus is lost. Such limitation would be expected even with the use of other novel approaches such as the RAPIDO® Dual Catheter System (Guidant Inc., St Paul, MN, USA), which may be of help in accessing such veins but provides little or no support unless the guiding sheath is advanced into the vein.
The main idea behind this current design is to maintain access to the coronary sinus and provide lateral access through which the pacing lead might be advanced out from the guiding sheath and into the coronary vein. Although it may not be necessary in the majority of patients, we have shown in this small and much selected group of patients the feasibility of such an approach. We believe that further modifications to the previous design may be considered. For example, to aid locating the side-hole with fluoroscopy, it would helpful to add a radio-opaque marker or a radio-opaque ring that surrounds the side-hole. In addition, the catheter body on the opposite end of the side-hole may be reinforced to avoid kinking in that particular location, a problem which we have not encountered in our small experience.
Although we have not encountered complications in this very small number of patients, we note that alteration of the introducer sheath described in this article may introduce deficiencies that could result in unexpected complications. Potential risks, at all stages of this technique, include kinking of the sheath, break up with distal embolization, LV lead entrapment, and lead dislodgment. Therefore, such alteration should be considered experimental until further studies are conducted and such sheaths are manufactured with such alteration incorporated.
We conclude that additional modification of existing catheters, particularly similar to the one described in this report incorporating a side-hole, ought to be considered in view of the variable anatomy encountered during implantation of CRT devices.
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References |
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