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Ann Thorac Surg 2005;79:1536-1544
© 2005 The Society of Thoracic Surgeons
a Department of Thoracic and Cardiovascular Surgery, The Cleveland Clinic Foundation, Cleveland, Ohio
b Department of Cardiovascular Medicine, The Cleveland Clinic Foundation, Cleveland, Ohio
c Department of Biostatistics and Epidemiology, The Cleveland Clinic Foundation, Cleveland, Ohio
Accepted for publication October 26, 2004.
* Address reprint requests to Dr Navia, Dept of Thoracic and Cardiovascular Surgery/F24, 9500 Euclid Ave, Cleveland, OH 44195 (E-mail: naviaj{at}ccf.org).
Presented at the Fortieth Annual Meeting of The Society of Thoracic Surgeons, San Antonio, TX, Jan 26–28, 2004.
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Abstract |
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 Top Abstract IntroductionPatients and MethodsResultsCommentDiscussionAcknowledgmentsReferences |
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METHODS: From October 2002 through October 2003, 41 patients underwent minimally invasive left ventricular lead placement, 23 (56%) by minithoracotomy and 18 (44%) endoscopically. Thirty-one (76%) were males, 19 (46%) had previous cardiac surgery, 21 (51%) had ischemic cardiomyopathy, 17 (41%) were in New York Heart Association class III or IV, and 28 (65%) had implantable cardioverter-defibrillators.
RESULTS: There were no in-hospital deaths, intraoperative complications, or failures to implant the left ventricular lead. Median operative time was longer for the endoscopic approach (188 minutes) than for minithoracotomy (151 minutes; p = 0.006). Preoperatively, the endoscopic group had more mitral regurgitation (median, 2.5 versus 1.0, respectively; p = 0.009). QRS duration was shorter postoperatively (mean change from preoperative, –32 ± 24 ms; p < 0.0001); this change was unrelated to surgical approach. Impedance also was less postoperatively (mean change, –490 ± 300 ohms; p < 0.0001), and the change was unrelated to surgical approach. Changes were greater the larger their preoperative values (p < 0.0001). Threshold increased with follow-up time (adjusted p < 0.0001), but impedance decreased (adjusted p = 0.0009); these trends were similar for both approaches. No changes were evident in left ventricular dimensions.
CONCLUSIONS: Minimally invasive left ventricular epicardial lead placement is safe and effective, offering selection of the best pacing site with minimal morbidity; it can be considered a primary option for resynchronization therapy.
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Introduction |
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TopAbstractIntroductionPatients and MethodsResultsCommentDiscussionAcknowledgmentsReferences |
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Usually, left ventricular lead implant is accomplished percutaneously through coronary sinus cannulation [5], advancing the lead into a major cardiac vein. Unfortunately, this technique is associated with long fluoroscopic times and is not applicable to all patients because of coronary sinus and coronary venous anatomy limitations. Early and late failure occurs in approximately 12% and 10% of procedures, respectively [6].
Epicardial lead placement is often a rescue procedure, so it offers advantages related to its safety and shorter implant time. Moreover, it allows visual selection of the best pacing site and multiplicity of pacing sites. Minimally invasive surgical procedures facilitate left ventricular lead placement and can be accomplished with low risk and similar or superior results to full thoracotomy [7].
The purpose of this study was to determine perioperative and early postoperative outcomes of minimally invasive left ventricular lead placement as a management strategy for heart failure, comparing minithoracotomy and endoscopic approaches.
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Patients and Methods |
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TopAbstractIntroductionPatients and MethodsResultsCommentDiscussionAcknowledgmentsReferences |
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There were 31 men (76%), and mean age was 68 ± 10 years (range, 44 to 83 years). Nineteen patients (46%) had previous cardiac surgery, including 16 coronary artery bypass grafting operations. Seventeen patients (41%) were in New York Heart Association functional class III or IV, 20 (49%) had dilated cardiomyopathy, and 21 (51%) had ischemic cardiomyopathy. Seventeen (41%) were admitted preoperatively with heart failure exacerbation, and 1 (2%) required preoperative inotropic support. All patients had left bundle-branch block, with a mean QRS duration of 186 ± 23 ms (range, 146 to 242 ms). All previously underwent transvenous endocardial lead placement in the right atrium and right ventricle; all 41 failed implantation of the left ventricular lead through the coronary sinus from a total population of 376 patients. Reasons for percutaneous left ventricular implantation failure are listed in Table 1. Twenty-eight (68%) patients had implantable cardioverter-defibrillators.
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Indication for a specific surgical approach was based on the following general guidelines. Minithoracotomy was selected for two patient populations: those with severely enlarged left ventricles and those who had undergone previous cardiothoracic surgery. In these patients, total thoracoscopic procedures would be difficult and potentially dangerous, because limited space restricts safe manipulation of the instruments, so they may inadvertently trigger life-threatening arrhythmias or hemodynamic compromise. Video-assisted thoracoscopic surgery was selected in patients with adequate anterior–posterior chest diameter; reoperations were not a contraindication, but minithoracotomy was preferred. Robotic assistance was selected in patients with small cardiothoracic ratio and was contraindicated in reoperations.
Surgical Technique
APPROACH
Surgical techniques have been previously described [8]. Intraoperatively, patients were routinely monitored using a pulmonary artery thermodilution catheter and transesophageal echocardiography. General anesthesia was carried out with double-lumen endotracheal intubation in 36 patients (88%).
MINITHORACOTOMY
The patient was placed in a supine position with the torso slightly rotated to the right (30-degree angle). A 3-cm- to 5-cm-long skin incision was made over the fourth or fifth left intercostal spaces just anterior to the mid-to-posterior axillary line. The thoracotomy was completed, and the left lung, if adherent, was dissected free and retracted posteriorly. The pericardium was opened anteriorly to the phrenic nerve, with special care being given to patients with previous heart surgery, particularly coronary artery bypass grafting. Exposure of the posterolateral wall of the left ventricle was facilitated by placing stay sutures in the pericardium. Two screw-in pacing leads were routinely used (Medtronic Model 5071 Pacing Lead, Minneapolis, MN). After the leads were placed and assessment made with a pacing system analyzer for thresholds less than 1 V, they were brought out of the chest cavity to ensure sufficient slack to allow free lung movement. They were then tunneled to the pacemaker generator pocket. The lead with the lowest threshold was connected; the other was capped and left as a backup. After adequate hemostasis, a size 10 Jackson Pratt drain was placed into the left pleural space.
VIDEO-ASSISTED THORACIC SURGERY
The patient was placed in a supine position with the left arm slightly below table level to prevent interference with tool manipulation during the procedure. Port position depended on heart size and position. A fifth and sixth space anterior and mid-axillary 10- to 12-mm port for tools and a second or third space mid-anterior clavicular 10- to 12-mm port for the scope were standard. Sometimes an auxiliary port was placed close to the scope port, allowing better exposure in placing the leads. Single-lung ventilation was started and, if necessary, supplemented with carbon dioxide insufflations at 8 to 10 cm H2O. The procedure was then carried out in the same fashion as for minithoracotomy, opening the pericardium 1 cm posterior and parallel to the phrenic nerve. The goal was to place the lead posterior to the obtuse marginal artery, adjacent to the anterior aspect of the left atrial appendage. The lead was screwed in by using either the Medtronic or the thoracoscopic grasping tool. The leads were then brought out through the second intercostal space port, tunneled to the pacemaker generator pocket, and connected. Hemostasis was obtained, and a size-10 Jackson Pratt drain was placed in the left pleural space through the auxiliary port.
ROBOTICALLY ASSISTED SURGERY
The patient was placed in a full left posterolateral thoracotomy position. The da Vinci Robotic Surgical System (Intuitive Surgical Inc, Sunnyvale, CA) was used. Working ports were placed in the posterior axillary line, adjusted caudad or cephalad depending on the angle to the left ventricle necessary to allow placing the screw-in lead. Flexibility in port positions was important, and these were adjusted on the basis of individual chest wall and cardiac anatomy. Often, the fifth intercostal space was used for the right instrument, seventh space for the camera, and ninth space for the left instrument. Leads were passed through an auxiliary port in the sixth space and fixed similarly to that described for the thoracoscopic method, but less space was needed for instrument manipulation. Both leads were tunneled as far anterior as possible to reach the generator pocket with ease. Air was evacuated from the pleural space, and a Jackson-Pratt drain was placed. The patient was reprepped and redraped in the supine position for hook-up to the generator.
SELECTION OF IMPLANTATION SITE
Selection of the best implantation site was made by echocardiography with tissue Doppler imaging in combination with intraoperative electrophysiologic measurements. Leads were positioned, but not fixed, on several spots of the left ventricular epicardial surface. The final site was chosen on the basis of the longest atrioventricular delay in activation. The target was the posterolateral wall of the left ventricle in most of the patients; we avoided areas of ischemic and scarred myocardium, particularly when the latter was covered with fatty or fibrous tissue. Just after implantation, myocardial performance with biventricular pacing was assessed by transesophageal echocardiography.
Postoperative Period
Patients spent brief periods in the intensive care unit and then were transferred to the regular nursing floor. The chest drain was removed on the first postoperative day if there was minimal output. Generally, a period of adjustment of medications was required at that point, as well as pain management. Usually, an echocardiography-guided optimization of biventricular pacing was performed on the second postoperative day.
Statistical Analysis
Descriptive data are presented as mean and standard deviation for continuous variables (median with 15th and 85th percentiles, equivalent to 1 standard deviation, for variables with skewed distributions) and frequency and percentiles for categorical variables. Group comparisons were made using Wilcoxon rank-sum and 
2 tests, respectively.
Paired changes for preoperative or intraoperative and early, in-hospital postoperative variables were calculated and evaluated with paired Student's t tests. Generalized linear models were used to assess paired changes with respect to surgical approach while adjusting for preoperative or intraoperative measurements.
Time-related echocardiographic and electrophysiologic variables measured postoperatively and at follow-up were evaluated with longitudinal methods [9]. Repeated-measures mixed models were formed for each variable to assess the effects of time from operation to echocardiography and type of surgical approach. Other models also adjusted for preoperative measurements. Sequences of four models were investigated for each variable: (1) time only, (2) time and approach, (3) time and preoperative value, and (4) time, approach, and preoperative value.
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Results |
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TopAbstractIntroductionPatients and MethodsResultsCommentDiscussionAcknowledgmentsReferences |
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Impedance also was less postoperatively (mean change, –490 ± 300 ohms; median, –470 ohms; p < 0.0001) and was unrelated to surgical approach. These changes were greater the larger the preoperative value (p < 0.0001).
Threshold increased by a median of 0.4 V in the endoscopic group, but fell by –0.1 V in the minithoracotomy group (p = 0.03).
In a generalized linear model for the threshold change, after adjusting for intraoperative value (p = 0.08), the increased threshold found in the endoscopic group versus minithoracotomy remained evident (p = 0.05).
Changes During Follow-Up Period
Threshold values increased with time (adjusted p < 0.0001; Fig 3), but impedance decreased (adjusted p = 0.0009; Fig 4), and these trends were similar for both approaches. Ischemic cardiomyopathy was associated with lower postoperative impedance (p = 0.003), even after adjustment for intraoperative impedance value. As of yet, changes in left ventricular dimensions are not evident.
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Comment |
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TopAbstractIntroductionPatients and MethodsResultsCommentDiscussionAcknowledgmentsReferences |
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Nevertheless, there is an important risk of failure associated with transvenous resynchronization therapy. Approximately a quarter of patients have transvenous implantation failure; only two thirds of selected patients experience improvement in functional capacity and quality of life. Reasons are multifactorial, and identifying predictors of implant failure is essential for selecting the most appropriate inclusion population.
Principal Findings
This study concerns rescue therapy for patients with implantation failure (11% of our institutional experience), mostly for anatomic reasons. Surgical approach was either endoscopic (video-assisted thoracoscopic surgery or robotic) or by means of minithoracotomy, and this study compares safety and efficacy of these two approaches. Both procedures were safe, with short procedure times, no implant failure, no mortality, and minimal morbidity. Both resulted in effective biventricular pacing with shortening of the QRS. Early after inserting the leads, threshold voltage rose. We do not know whether it will stabilize, but to date, no patient has been unable to be paced. The reason for rising threshold may relate to type of lead used. Screw-in leads are known to have inferior performance to steroid-eluting leads [14], and this represents a specific drawback of the minimally invasive approach, which precludes technically demanding suturing of leads.
What Are the Most Appropriate Indications for Biventricular Pacing?
Recent studies suggest that acute hemodynamic improvement is most likely to be observed when QRS duration is greater than 150 ms in patients with left bundle-branch block. It is unknown whether patients with right bundle-branch block or nonspecific intraventricular conduction delay have similar benefits. The degree of left ventricular systolic functional impairment necessary to derive benefit from resynchronization therapy must also be defined. For example, it has been suggested that left ventricular pacing most likely provides hemodynamic improvement when the maximum rate of increase of left ventricular pressure is less than 700 mm Hg/s [15]. Most importantly, when analyzing reverse remodeling as an index of success, biventricular pacing is associated with approximately 50% response [16], defined as a greater than 15% reduction in left ventricular end-systolic volume by echocardiography with tissue Doppler imaging. Yu and colleagues [16] showed that responders had improved clinical status, cardiac function, and systolic synchronicity. On the other hand, nonresponders had only a small degree of clinical improvement in functional class and quality-of-life scores, with no change in cardiac function and worsening of systolic dyssynchrony. Direct assessment of systolic synchronicity by tissue Doppler imaging identified a preimplant dyssynchrony index of 32.6 ms as a predictor of response to therapy.
Will Biventricular Pacing Improve Survival of Patients With Advanced Heart Failure?
Leclercq and colleagues [17] suggest that the extremely high mortality (55% in 12 months) of patients in New York Heart Association class IV is unlikely to be importantly improved by ventricular resynchronization therapy. Because such patients have a strong tendency toward ventricular arrhythmias, implantable cardioverter-defibrillators may improve outcomes. Although disease criteria have never been established, biventricular pacing might benefit patients before they reach end-stage biochemical heart failure.
The cause of cardiomyopathy may influence responsiveness to biventricular pacing. In this study, ischemic cardiomyopathy patients had worse electrophysiologic performance (lower postoperative impedance) than dilated cardiomyopathy patients. Although no clinical implications of these findings were observed, further studies with longer follow-up are needed to address this issue.
Totally Transvenous Biventricular Lead Implantation and Procedural Limitations
Transvenous left ventricular lead implantation is technically difficult, frequently requiring extensive fluoroscopic times. Success depends on coronary venous anatomy. Despite the considerable variability of the coronary venous system among patients, a lateral vessel for lead introduction was available in 82% in a patient population that could potentially benefit from a left ventricular lead [18].
Failure to cannulate the coronary sinus is the most frequent reason for failure of lead implantation, as demonstrated in our experience. Other reported causes are failure of appropriate capture, lead dislodgement, perforation, dissection, and phrenic nerve or diaphragmatic stimulation. Early and late failure occur in approximately 12% and 10% of patients, respectively [6].
Furthermore, in the MIRACLE implantable cardioverter-defibrillator trial [1], 28% of the patients experienced complications between implant and hospital discharge, most of which related to coronary sinus dissection, perforation, heart block, and pericardial effusion. In another relevant study, the endocardial approach was unsuccessful in 8% of patients [19]. Serious complications occurred, such as refractory hypotension, bradycardia, or asystole in 4 patients (2 of whom died) and perforation of the coronary sinus requiring pericardiocentesis in 2 others.
As demonstrated by our experience, cases reserved for epicardial lead placement were only those in which there had been a failure of coronary sinus lead insertion. Based on these limitations of endocardial placement, direct approaches are becoming critically important for ventricular resynchronization therapy and biventricular pacing.
What Is the Best Left Ventricular Pacing Site?
Importance of the site of left ventricular stimulation is increasingly appreciated. It has been shown that hemodynamic improvements are greater during stimulation within the lateral branches of the coronary sinus than within the great cardiac vein, corresponding to the midlateral and posterior wall of the left ventricle [20]. This site may provide early excitation in the region with the greatest baseline delay in activation and can help reduce mitral regurgitation by prestimulating the papillary muscle. Placing multiple leads (or multiple electrodes in one lead) may provide further advantages, but this strategy is still under investigation.
Because transvenous implantation is dependent on coronary venous anatomy, lead implant in an ideal site is difficult and demanding. Placing the lead in the anterior venous system may actually worsen hemodynamic indices because of early stimulation of the interventricular septum with loss of left ventricular synchrony. In contrast, the epicardial approach allows more freedom in selecting the pacing site while monitoring hemodynamic response in the operating room. Potentially combined electrophysiologic and echocardiographic mapping could guide the surgeon to the best area of latest electrical activation, avoiding areas of scarred myocardium. Most recently, pressure–volume loops have effectively targeted the best epicardial pacing site [21]. This emerging technology may enhance the success of biventricular pacing in heart failure patients.
Limitations
This study represents our early experience with minimally invasive surgical placement of left ventricular leads. This is a select group of transvenous implant failures; we do not have direct data comparable with the percutaneous approach. In addition, the small number of patients and short follow-up limit identification of differential effects such as type of myocardial disease or demonstration of changes in left ventricular dimensions and reversal of ventricular remodeling.
Conclusions
Minimally invasive surgical techniques proved to be feasible and safe, as previously shown [22]. They confer procedural advantage over the percutaneous approach, mainly related to shorter implant time and visual selection of the best pacing site and multiplicity of pacing sites, which can be guided by echocardiography with tissue Doppler imaging or pressure–volume loops.
Although endoscopic techniques required longer implant times than minithoracotomy, both approaches showed similar early results. We recommend these two approaches to diverse target populations. Minithoracotomy should be reserved for patients with severely enlarged hearts. By contrast, endoscopic approaches should be selected for patients with adequate anterior–posterior chest diameter. Reoperations should be preferentially performed by minithoracotomy because of safety concerns.
Minimally invasive left ventricular lead placement appears from this limited study to be a viable management strategy for heart failure. It carries minimal morbidity and should be considered a primary option for resynchronization therapy. Further studies with longer follow-up comparing surgical and percutaneous approaches are necessary, as are studies of the electrophysiologic performance of epicardial leads.
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Discussion |
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TopAbstractIntroductionPatients and MethodsResultsCommentDiscussionAcknowledgmentsReferences |
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Now, I realize that it is probably impossible to implant them using a robotic system, which I am familiar with. So, therefore, we prefer the minithoracotomy and then carefully place these nonpenetrating steroid-eluting leads for durability. We have follow-up up to 12 years, because at the end of 12 months you probably still have a good result with these leads, but eventually it is going to lead to increasing thresholds and fibrosis, and you are going to have to go back and replace them—if the patient is still alive, of course.
Thank you.
DR NAVIA: I think we could agree with your comments. For a thoracoscopic or robotic approach, it is easy to use the screw-in lead as well as safe for the patient and practical. I think steroid-eluting leads will be better for the long-term threshold, but it is sometimes difficult to put a stitch in a beating heart with a very dilated and fragile epicardial surface. In these cases, I prefer to use an epicardial screw-in lead. We know that at 13 years, 85% of these leads maintained good thresholds.
DR SULAIMAN HASAN (Charleston, WV): I enjoyed your paper, Jose. My question was how many of these patients have previously had heart operations among your series, and if so, how did that alter your approach, because in my experience it does complicate matters a bit?
DR NAVIA: Forty-six percent of the patients in our study had previous cardiac surgery, mostly coronary artery bypass grafting. In this kind of population, we can use two different techniques. One is minithoracotomy, for patients who have large ventricles close to the ribs and do not have space for manipulation of thoracoscopic instruments. The second is video-assisted thoracoscopic surgery, for patients whose anterior-posterior chest dimension has enough space for surgical tools to be manipulated without damaging the heart or lungs. To select the specific surgical technique, we usually check chest X-ray and computed tomographic scan to see the anatomic position and diameters of the heart and the left lung related to the chest. I have not done a reoperation with robotic-assisted surgery.
DR MIKE BANKER (Newark, NJ): Did you notice any clinical or electrophysiologic differences between the video-assisted thoracoscopic surgery–placed leads and the robotic-placed leads? I realize the number was only four in the robotic group, but were there any clinical or electrophysiologic differences between those two groups?
DR NAVIA: No. We didn't see any difference before or after surgery in terms of demographic, electrophysiological, clinical, or surgical outcome between video-assisted thoracoscopic surgery and robotic-assisted surgery.
DR MICHAEL ARGENZIANO (New York, NY): Jose, great work as usual. I was very impressed. I have just a quick comment and a question. With respect to these steroid-eluting leads, I agree that they are superior, and in fact we have placed them robotically. This is actually one of the main arguments in favor of the robotic approach, because there might be those who would say, "why use a robot if you can do this thoracoscopically just as easily by screwing the lead in?" So the robot does give us the dexterity to do that, and things like using the coalescent U-clips may actually make that procedure simpler than it may appear.
My question relates to your patients that you listed with ventricular fibrillation. We had 1 patient in whom we converted a robotic operation to a thoracotomy because the patient fibrillated and we could not shock the patient back with external paddles in the operating room, and obviously this is a risk that you take any time you operate on patients with poor ejection fractions. So the question I have is, when did those episodes of fibrillation occur, and if they did occur in the operating room, did you consider placing combination pacemaker-defibrillators in those patients?
DR NAVIA: That is a good point, because when we start surgery, we turn off the implantable cardioverter-defibrillator (ICD), so fibrillation can happen during surgery. And most of the patients, around 70%, come to the operating room with an ICD in place. To try to evaluate if the rest of the patients needed an ICD placed at the time of lead placement is very difficult.
The COMPANION and then the MIRACLE ICD study show that the most benefit in terms of long-term survival is realized with biventricular pacing plus ICD. But it is a new field, and we need to continue our research to find out the best strategy. I agree with you, though, that ICD placement at the time of biventricular pacing will likely be shown to be a good idea.
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Acknowledgments |
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TopAbstractIntroductionPatients and MethodsResultsCommentDiscussionAcknowledgmentsReferences |
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