Cardiac resynchronization therapy (CRT) is an effective treatment for patients with advanced functional congestive heart failure and intraventricular conduction abnormalities. Patients treated with CRT experience an improvement in exercise capacity and quality of life and a significant decrease in congestive heart failure–associated morbidity and mortality.1–4 The left ventricular (LV) lead is typically placed percutaneously via the coronary sinus, is associated with longer operative times compared with right atrial and ventricular pacing lead placement, has limited site options, and has an implantation failure rate of 10% to 30%.5,6 With the advent of minimally invasive techniques, including robotic-assisted (RA) telemanipulation using the daVinci Surgical System (Intuitive Surgical Inc, Sunnyvale, CA USA), epicardial LV lead placement with minimal surgical morbidity is offered at many centers.7,8
Minimally invasive LV epicardial lead insertion is performed via a thoracoscopic, RA, or minithoracotomy (MT) approach. DeRose and colleagues9,10 suggest that a posterior RA approach with the daVinci Surgical System can facilitate more precise placement of the epicardial lead with optimal posterolateral LV wall position. Critics of the RA technique argue that advances in basic minimally invasive practices facilitate safe epicardial LV lead placement without the use of a surgical robot.11,12 The MT minimally invasive approach using specialized instruments originally developed for port-access mitral valve surgery allows placement of the LV lead on the posterolateral LV wall as an alternative method.
Our center offers both these options for epicardial LV lead placement. The efficacy of either approach has not been directly compared, and we postulated that the RA approach was superior to the MT approach for epicardial LV lead implantation. We examined our single-surgeon experience while analyzing early outcomes, standard electrophysiologic metrics, and resource utilization of RA and MT minimally invasive approaches.
Between January 2005 and April 2010, all patients referred to our facility after failed percutaneous LV lead implantation were reviewed. Patients were stratified by RA or MT minimally invasive epicardial LV lead placement. The surgeon was experienced with the robot at the point we started to place epicardial leads with the device, having successfully completed more than 20 robotic cases before starting the placement of LV epicardial leads using the robot. Protocol-driven postoperative care comanaged by the surgeon and pulmonary intensivist was standardized across groups. Follow-up with the surgeon was scheduled at 3 weeks after operation, whereas the referring cardiologist manages subsequent cardiovascular care.
Initially, patients undergo right atrial and right ventricular transvenous endocardial lead placement. The RA epicardial LV lead implantation with the da Vinci Surgical System is performed after double lumen intubation. With the patient in a posterolateral thoracotomy position, the surgical arms are inserted at the fifth and ninth intercostal spaces (ICSs) through two small incisions (3 cm each) that are made posterior to the posterior axillary line. Similarly, the endoscopic arm is introduced through the seventh ICS slightly posterior on the chest wall. The ports are adjusted commensurate with the patient’s thoracic anatomy. The left lung is deflated and retracted posteriorly to identify the phrenic nerve, posterior to which a 1- to 2-cm longitudinal pericardotomy is completed. After, obtuse marginal artery (OM) identification mapping for threshold and impedance is completed, and the most optimal position is chosen for lead placement where pacing analyzer thresholds less than 1 V are identified. The mapping process includes identifying a bare muscular area in the posterior lateral wall where a lead is placed and standard threshold testing is attempted. Therefore, this may require multiple attempts if the threshold is not satisfactory. Two pacing leads are screwed in with distal fixation. The pericardium is closed carefully over the two leads to aid in preventing lead migration, after which the pacing analyzer retests both leads for optimal threshold. The lead with the lower threshold is chosen for connection, whereas the other is either left capped in the pocket as a backup or connected to the other lead in a bipolar configuration depending on the pacing thresholds. Both leads are brought out of the chest cavity with sufficient slack to allow free lung movement, tunneled to the pacemaker generator pocket, while the selected lead is attached. A single tube thoracostomy is then performed, incisions are closed, and patients are extubated in the operating room before transfer to the cardiac intensive care unit.
Initially, patients undergo right atrial and right ventricular transvenous endocardial lead placement. The MT epicardial LV lead implantation is performed using double lumen intubation as well. After successful endotracheal intubation, the patient is placed in the right lateral decubitus position, with the left chest accessible at an angle of 30 degrees or greater. After confirmation of (left) lung deflation, a 3- to 5-cm left anterolateral MT incision is made between the fourth and sixth ICSs between the middle and posterior axillary lines to access the left pericardium. The phrenic nerve is visualized, and a 1- to 2-cm longitudinal pericardotomy posterior to the nerve is completed, and the pericardium is retracted with stay-sutures to facilitate posterolateral LV wall exposure. No endoscope is used for MT epicardial LV lead implantation.
Once the left OM is identified, mapping for threshold and impedance is pursued, and the most optimal position is chosen for lead fixation (screw-in) near the OM where pacing analyzer thresholds less than 1 V are identified. The mapping process includes identifying a bare muscular area in the posterior lateral wall where a lead is placed and standard threshold testing is attempted. Therefore, this may require multiple attempts if the threshold is not satisfactory. Subsequently, a second lead is screwed in to the posterior LV wall. The pericardium is closed carefully over the two leads to aid in preventing lead migration, after which the pacing analyzer retests both leads for optimal threshold. The lead with the lower threshold is selected for connection, whereas the other lead is capped and serves as a backup or is connected to the other lead in a bipolar configuration depending on the pacing thresholds. Both leads are brought out of the chest cavity with sufficient slack to allow free lung movement, tunneled to the pacemaker generator pocket, while the selected lead is attached. Upon completion, a tube thoracostomy is placed in the pleural space for drainage. Patients are extubated in the operating room and transferred to the cardiac surgery intensive care unit.
Cardiac surgery quality control information at our institution is maintained based on the criteria defined by The Society of Thoracic Surgeons (STS) national database.13 All variables were analyzed per STS definitions (version 2.61). Approval for this investigation, including patient consent waivers, was obtained from the State University of New York Upstate Medical University Institutional Review Board (no. 40-10).
The Social Security Death Index (SSDI) was also queried to determine mortality at 1 year after surgery. The SSDI is a database of death records abstracted from the US Social Security Administration’s Death Master File.
A comprehensive retrospective chart review was completed; two investigators independently extracted operative summaries and all outpatient office visits. Interobserver concordance was not assessed.
Direct cost data, as defined by our institution’s finance department, were obtained from billing records (physician and hospital) based on the American Medical Association’s 2010 Current Procedural Terminology codes. Direct costs are those incurred during the procedure from skin incision to closure and include the cost of operative time (approximately $1200 per hour).
Statistical Package for the Social Sciences version 19 (SPSS Inc, Chicago, IL) was used for the analysis. The strength of association for each variable was measured using the appropriate statistical hypothesis test. The significance of differences in proportions for categorical variables was evaluated by the Pearson χ2 or Fisher exact test where appropriate (P < 0.05). The significance of differences in mean values for continuous variables was assessed using single factor analysis of variance models (P < 0.05). Results for the total series of hypothesis tests conducted in the study population were corrected for multiple comparison bias by adjusting each probability by the false discovery rate.
Data from the 24 patients analyzed were stratified by minimally invasive technique into either RA (n = 10) or MT (n = 14). Preoperative characteristics between groups were similar (Table 1). Notably, the mean age of patients who underwent RA was 12 years younger than that of the MT cohort (P = 0.03). Although mean body surface areas between groups were similar, mean body mass index was 18 kg/m2 higher in the RA group (P = 0.003) and accounts for the more than 23 kg weight difference compared with MT patients (P = 0.03). Most patients in either group were New York Heart Association Class III or IV functional heart failure candidates, with a mean ejection fraction of 28.9% ± 13.7%. Furthermore, 70.0% of RA and 78.6% of MT patients had previous implantable cardioverter defibrillator placement, with 92% of patients having undergone at least one previous cardiovascular reoperation, whereas a majority (54.2%) of them had undergone a second or third reoperation as well.
The SSDI query identified two patients in the MT group who were deceased 1 year after surgery, but no specific information regarding causation was available. The two deaths occurred in patients with New York Heart Association Class IV functional heart failure who became refractory to biventricular pacing. Neither patient had specific surgery-related complications but died secondary to intractable heart failure.
Perioperative Electrophysiology and Outcomes
There were no significant differences in impedance, pacing threshold, or absolute QRS duration between groups (Table 2). As expected, relative mean preoperative versus postoperative QRS durations (milliseconds) were different (RA, 161.3 ± 28.9 vs 135.4 ± 14.6, P = 0.002; and MT, 179.6 ± 27.2 vs 147.5 ± 28.5, P = 0.001). There were no differences in early outcomes between groups (Table 3).
Resource Utilization and Costs
There were no differences in lengths of stay between groups, with the mean hospitalization lasting 4 days, of which intensive care stay accounted for almost 94 hours, irrespective of the operation (Table 4).
Importantly, operating room time from entry to exit was more than an hour longer (Fig. 1) with RA compared with MT (P < 0.001). Ventilation time was more than 75 minutes longer with RA compared with MT (P < 0.001). Furthermore, the incision was closed 48 minutes sooner when the MT minimally invasive approach was used (P = 0.002). The absolute direct costs were similar between groups (Table 4).
This study compares our early experience with epicardial LV lead implantation using two minimally invasive approaches. Our cardiac center offers both RA and MT incision epicardial LV lead placement. The patients who underwent either procedure at our center had equivalent premorbid profiles. Interestingly, younger patients who were selected for RA also had higher body mass index compared with patients selected for the MT approach. Both procedures were effective and safe, with no implantation failure and short-term morbidity or mortality, and achieved effective ventricular pacing with shortened postprocedural QRS interval. Both procedures were performed contemporaneously, and there have been no cases where a switch to the backup lead was necessitated by deteriorating pacing thresholds. In contrast to our hypothesis that the RA approach would be better than MT minimally invasive LV lead implantation, we found that there was no difference in the clinical outcomes between the two groups. In addition, MT had shorter operative time compared with RA.
Cardiac resynchronization therapy has gained popularity in the past decade, and clear benefits have been demonstrated in patients with end-stage heart failure. Nevertheless, the success of the procedure is dependent on the ability to accurately place leads that would successfully accomplish this goal. The endovascular approach is traditionally the preferred method, although sometimes, lead failure rates require an open approach as an appropriate alternative. However, most of these patients have undergone previous heart procedures, making lead placement a challenge. Approach through the left chest has been preferred in such circumstances, but maneuverability of the cardiac structures becomes a challenge because of the scarring and adhesions from previous surgery. Because these patients are physiologically more tenuous, minimally invasive approaches are touted as an appropriate strategy, as these are associated with limited surgical trauma and potentially faster recovery times.
Although RA endoscopic techniques require longer implantation times than MT techniques do, both approaches had similar electrophysiological results. Although our study did not address this question, it could be argued that reoperations should be preferentially performed by the MT approach because of enhanced tactile feedback and direct access to the operative field. Although fine motor control seems to be an advantage with RA, the significantly diminished tactile feedback and consequent impact on haptics seem to offset this potential benefit. Although the patients who undergo CRT are a small subgroup of patients who had undergone multiple previous catheter-based interventions and open surgical procedures, it should be acknowledged that these are a select subgroup of very sick patients. Offering an open surgical operation in the setting of a previous open surgical intervention requires careful consideration of the risk and benefits because these are still high-risk operations; hence, expeditious completion with less exposure to anesthesia and lower operative times are favorable. Although RA allows tremendous maneuverability and may offer an advantage in obese patients, the longer operative times or costs may not necessarily be justified. The additional setup time for equipment and longer room turnover time associated with robotic procedures are more likely to be higher compared with the MT and may not be financially justifiable in an era of diminishing medical reimbursements.
From the data presented herein, one could conclude that the MT approach is better than RA for LV lead implantation and that, perhaps, robotics ought to be abandoned for, at least in part, reasons of time. Hence, a caution to the reader is warranted, in that if robotics is skipped for this procedure, then an opportunity to develop this stepping stone into more complex totally endoscopic procedures in heart surgery is missed. Importantly, robotic surgery can serve as a teaching operation and a general platform to achieve improved robotic skills. Notably, given that early development of laparoscopic procedures also involved longer operative time and costs and because the academic community is charged with the task of greater innovation, these investments should probably be taken toward the development of potentially better procedures.
Of note, there are a few limitations to our study. Because this is a retrospective analysis, there is inherent bias that limits our ability to analyze variables outside the STS database. Our observational study might not effectively detect small differences between associations that exist with these data. Likewise, given the size of the study population(s), the possibility of a type II error during comparisons cannot be excluded. Regional referral patterns and clinical practice of cardiologists would influence patient admixture, incorporating a selection bias. As such, our smaller single-center, single-surgeon series might limit external validity. The study focuses only on the short-term outcomes of these patients, even though two SSDI queried mortalities were noted in the MT group at 1 year. Long-term outcomes such as durability of the leads, change in impedance of the leads over time, need for reinterventions, and long-term survival between differences in the two study groups are unknown. In addition, the therapy is offered to a highly select subgroup of patients, and to this end, a randomized trial would not be financially viable or justifiable. Postoperative pain and thoracotomy-related pain syndromes are other quality-of-life issues that may potentially impact the long-term benefits of the RA approach. The two groups of patients were somewhat different with a preponderance of obese patients in the robotic group, which could also bias the results.
Minimally invasive LV lead placement is a viable management strategy for heart failure. It carries minimal morbidity and should be considered a primary option for resynchronization therapy in select patients. Specifically, the MT approach for lower volume centers appears to be more favorable than the RA approach, given the outcomes versus cost-to-benefit ratio. Further studies with longer follow-up comparing RA and MT are necessary, as are studies of electrophysiologic performance of epicardial leads.14 Although RA techniques are used more commonly in obese patients, the equivalent results to the MT approach may support the preferential use of a robot in obese patients where visualization though MT approach may be compromised.
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This small single-center experience describes 24 patients undergoing minimally invasive robotic-assisted or minithoracotomy epicardial left ventricular lead placement for resynchronization. This is a retrospective observational study. The authors found that both the operating room and the mechanical ventilation duration were higher with robotic assistance than with the minithoracotomy approach. The incision to closure interval was 48 minutes shorter in the minithoracotomy patients. The authors suggest that the minithoracotomy approach is a superior one for epicardial resynchronization.
The limitations of this study are its small size and its retrospective nature. The question of which approach is most beneficial would best be answered by a prospective, randomized trial, but this would be difficult in the highly select subgroup of patients undergoing these procedures. The study does suggest that using expensive robotic systems that were designed to facilitate endoscopic microsurgery is likely not necessary for simple procedures that can be easily done by hand with a thoracoscopic approach. Further studies are needed to clarify this issue.
Keywords:Copyright © 2012 by the International Society for Minimally Invasive Cardiothoracic Surgery. Unauthorized reproduction of this article is prohibited.
Robotic assisted; Minithoracotomy; Left ventricular lead implantation; Resynchronization; Cardiac surgery