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Ann Thorac Surg 2003;76:413-417
© 2003 The Society of Thoracic Surgeons
a Department of Cardiac Surgery, Erasme University Hospital, Brussels, Belgium
b Department of Cardiology, Erasme University Hospital, Brussels, Belgium
Accepted for publication February 21, 2003.
* Address reprint requests to Dr Jansens, Department of Cardiac Surgery, Erasme University Hospital, 808 Route de Lennik, 1070 Brussels, Belgium.
e-mail: jjansens{at}ulb.ac.be
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Abstract |
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METHODS: A total of 15 patients were included in this study. Right (atrial and ventricular) leads were implanted classically through the left subclavian vein. Robotic-enhanced thoracoscopy was then performed to implant the LV epicardial lead.
RESULTS: Of the 15 patients, 13 underwent successful endoscopic robotic cardiac resynchronization therapy. Two patients underwent conversion to a small thoracotomy. No perioperative complication occurred in the patients who did not undergo conversion. Acute and chronic LV lead thresholds were satisfactory in all patients, improving over time. All were subjectively and objectively improved at 4 months. As compared with conventional methods, the procedural cost was not significantly affected.
CONCLUSIONS: Based on this feasibility study, we believe that robotic LV epicardial lead implantation is a valuable option to achieve biventricular resynchronization therapy. It allows for more reproducible acute thresholds for LV pacing and sensing than does the percutaneous approach; enables fine tuning of the LV lead position, thus potentially providing optimal hemodynamic benefit; and avoids the pitfalls and limitations of the endovenous approach. Therefore it deserves further prospective studies to assess its place in the therapeutic armamentarium against heart failure.
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Introduction |
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TopAbstractIntroductionPatients and methodsResultsCommentReferences |
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Because of these technical drawbacks and complications of the endocardial approach, there seems to be room for the development of an alternative implantation technique.
Although probes were implanted surgically in the early days of pacing and defibrillation therapy, in the past few years the surgical approach has generally been regarded as a "worst-case scenario" in pacemaker or defibrillator implantation. It requires a thoracotomy or sternotomy, both carrying a high morbidity rate among debilitated individuals; it also significantly affects the cost-effectiveness of the procedure, mostly through an increase in the length of hospital stay and hospital charges [9].
Moreover, because of the lack of industry interest in developing the appropriate epicardial probe technology, epicardial leads have not provided satisfactory long-term pacing and sensing thresholds as stable as those of endocardial leads. Such epicardial leads have been prone to long-term failure due to fracture and loss of pacing.
Thus, surgical epicardial pacing lead implantation has maintained only very limited indications such as in treating the pediatric population, infection of endocardial leads, or thrombosis of venous implantation sites [10, 11].
Robotics has launched the era of totally endoscopic cardiac surgery procedures, with particular focus on totally endoscopic coronary artery revascularization [12]. This technology enables precise closed-chest surgical maneuvers and, in particular, provides perfect visualization of the entire antero-lateral LV wall that is the target of epicardial lead placement.
Therefore, with the background of experience in the field of totally endoscopic coronary artery bypass surgery, we believed that CRT could potentially benefit from this approach, combining the advantages of thoracotomy (excellent visibility and ease of surgery) and those of video-assisted thoracoscopic surgery (minimal incisions and postoperative pain).
In the current pilot study, we evaluated the feasibility of epicardial lead implantation through robotic-enhanced thoracoscopy for cardiac resynchronization in the treatment of heart failure.
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Patients and methods |
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There were 11 men and 4 women, with a mean age of 71.2 ± 5.8 years. Average NYHA class was 3.1 ± 0.72. Dysrythmias included an enlarged QRS in 15 cases, atrioventricular block in 7, atrial fibrillation in 1, and ventricular fibrillation in 5. Mean QRS duration was 168 ± 19 milliseconds and mean ejection fraction was 23.6 ± 5.8. Operative times, complications, and costs associated with the procedure were recorded.
Operative technique
After conventional, percutaneous, fluoroscopy-guided implantation of the right atrial and ventricular leads, three 1-cm incisions are made in the second or third, fourth, and seventh intercostal spaces, along the left midaxillary line, allowing the introduction of two lateral robotic arms and one central three-dimensional camera into the chest. Gentle CO2 insufflation and 30-degree right lateral tilting of the patients are mandatory to provide a sufficient amount of working space between the dilated left ventricle and the chest wall. The surgeon, positioned at a distance from the patient at the operating console, performs the operation by remotely telemanipulating the endoscopic arms and camera as described elsewhere [12].
A left lateral pericardiotomy is performed with an articulated cautery hook to expose the LV lateral wall, and the lead is positioned under direct vision after having been inserted into the thorax through a fourth lateral 8-mm port. The lead is attached to the epicardium according to visual assessment of local viability (aspect and contractility) by means of a 4-0 Ticron suture (Davis & Geck, St. Louis, MO), which is secured in the myocardium. After completion of the threshold measurements and echocardiographic assessment of resynchronization efficiency, a second stitch is placed in the epicardium around the electrode’s neck on a lead reinforcement designed for the purpose; in the last 3 patients a "pericardial bridge" was made to secure the trajectory of the distal electrode (Fig 2). This maneuver has been very helpful, as it holds the neck of the probe in contact with the lateral wall during the stitching of the electrode. The proximal aspect of the lead is then brought through the second intercostal space to be connected to the stimulator and placed in a conventional pectoral position. All of the LV pacing leads were conventional unipolar or bipolar epicardial electrodes (CAPSURE-EPI 4965 Medtronic Inc, Minneapolis, MN, or MX-BP 50 Biotronik GmbH, Berlin, Germany).
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Results |
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Functional status was assessed by a 6-minute walking test and NYHA clinical scoring. Both were found to be improved 4 months postoperatively in all patients, which was statistically significant (p < 0.01) (Table 1).
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The specific cost incurred in using the robot for this procedure was 700 euros, excluding the capital equipment cost of the da Vinci system itself. The average length of stay was 4.6 ± 2.1 days.
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Comment |
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Although a percutaneous approach through the coronary sinus is the route of choice to achieve LV epicardial lead placement, its procedural success rate is only approximately 70% to 90%. In a series of 43 patients, Butter and colleagues [13] reported that 30 patients were successfully received stimulation; the remaining 13 (30%) had either a placement or stimulation failure.
Several reasons for failure, related to either the operator himself or to the probe technology, can be identified. Both of these factors, however, can be improved over time. First, the procedural learning curve is, by definition, a temporary issue in the presence of a sufficient case load, and improving the electrodes depends on the willingness of the pacing manufacturers. Second, other issues such as high thresholds, phrenic nerve stimulation, or lead displacement may be unavoidable and may adversely affect the procedural success rate. Third, as mentioned above, the percutaneous approach strongly depends on the coronary venous anatomy, thus leading to unpredictable reproducibility.
Finally, fracture or infection of such leads may generate major morbidity. Because of the lead adhesion into the coronary sinus, its removal can be extremely hazardous. The success of coronary sinus lead reimplantation in this case is extremely unlikely.
Moreover, as reported by Butter and colleagues [13] in the above-mentioned study, the LV stimulation site is key to achieving a significant improvement in hemodynamics: CRT with lateral free wall stimulation produces significantly better systolic performance compared with anterior stimulation; the latter position (which is achieved through an anterolateral minithoracotomy) could even worsen LV function [12].
This clearly advocates for an accurate positioning of the LV lead on the lateral wall, circumvening the maximal ventricular mass between the right and left ventricular electrodes. In coping with this requirement, surgical epicardial stimulation is advantageous, as it enables targeting of any aspect of the lateral wall and eventually relocating the electrode in case of insufficient hemodynamic benefit. On the other hand, the classic surgical approach to implantation bears a significant rate of complications in the compromised CHF patients who require CRT, those complications accounting for a significant increase in length of stay and hospital cost.
Because of this paradigm and the aim to enhance the reproducibility of CRT, we adapted the robotic-enhanced CRT as an alternative to the existing approaches. It is noteworthy that the only two complications of the present report occurred in the first 2 patients, who had undergone conversion. This illustrates the high rate of pulmonary complications after thoracotomy in CHF patients. In the remainder of the group, the short procedural time associated with the absence of thoracotomy may have been the reason for the absence of postoperative complications.
Notwithstanding the learning curve, those procedural times can be compared favorably with the reported procedural times of endovenous lead positioning, which can be time consuming.
Three patients included in the study had undergone a failed percutaneous implantation: after 4 hours of unsuccessful attempts because of very high thresholds, the cardiologists had decided to send these patients to surgery. In those cases the preoperative echocardiogram (or echocardiogram and positron emission tomographic scan) showed a large, nonviable LV lateral area, and the robotic-guided epicardial lead was uneventfully placed on a lateromedial area under direct vision of the heart.
Direct vision with the robotic system enables gross evaluation of the functional status of the ventricular wall at the implantation site. Viable functional myocardium can be easily distinguished from scar tissue; where the myocardium is contracting, there is a high possibility of good electrical conduction.
In fact, in this series, no epicardial lead had to be repositioned, the thresholds were readily acceptable and the operative electrocardiogram showed a much thinner QRS wave at the first stimulated position. As mentioned above, the long-term pacing and sensing thresholds of epicardial probes have been a matter of concern, but recent studies reported similar effectiveness for epicardial and endocardial leads [14]. Although the present study was not comparative, we report as an indication the pacing and sensing thresholds of a historical biventricular resynchronization cohort from our department in Table 2.
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Another limitation of RCRT may be found in the timeline: technical surgical advances are facilitating the operation every time. One can thus anticipate that specifically designed tools and enabling technologies are going to make the robotic technology unnecessary, the operation being performed easily with "classic" thoracoscopy.
Functional tests showed postoperative improvement in every patient in our study, in keeping with data from the literature. Not a single patient in this limited series was functionally nonresponsive to the therapy. This requires further prospective investigation, but could correspond to a better stimulation site selection.
Based on the encouraging results of this feasibility study, we can conclude that robotic LV epicardial lead implantation is relatively easy to perform and valuable for determining the target stimulation zone. By enabling fine tuning of the LV lead position, this technique may provide optimal hemodynamic benefits with low rate of complications. It may also become attractive as an alternative to the percutaneous approach, in particular with the development of improved epicardial electrodes. Further studies will define the place of RCRT in the therapeutic armamentarium of heart failure treatment.
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References |
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