History
The patient has an extensive cardiac history, beginning with a myocardial infarction and subsequent coronary artery bypass and three grafts in 1988. In 2002, he underwent a reoperative three-vessel bypass. He was diagnosed with sick sinus syndrome in 2001 that required the implantation of a dual-chamber pacemaker. The device was updated to an implantable cardioversion defibrillator (ICD) in 2002 after he experienced cardiac arrest. He was successfully resuscitated without neurologic sequelae. The prior right ventricular lead was abandoned and capped, and the patient received a dual-coil high-voltage lead. The generator was replaced in 2005 and again in late 2011. On the current admission, the patient had poorly controlled hypertension and worsening heart failure in the setting of chronic right ventricular pacing. Left ventricular ejection fraction had fallen from greater than 55%, 1 year previously, to 31%. The patient experienced progressive dyspnea on exertion.
Current Medications
The patient was taking aspirin 81 mg daily, atorvastatin 80 mg daily, candesartan 16 mg daily, carvedilol 12.5 mg twice daily, dutasteride 0.5 mg daily, niacin 500 mg daily, and spironolactone 25 mg daily.
Physical Examination
Laboratory Data
Electrocardiogram
Findings
The electrocardiogram revealed atrial-sensed ventricular-paced rhythm (Figure 21-1), with a heart rate of 62 bpm and QRS duration of 192 msec.
Sinus bradycardia with underlying left bundle branch block also was seen (Figure 21-2). The heart rate was 59 bpm and QRS duration 132 msec.
FIGURE 21-1 Electrocardiogram before the battery change. SVG-OM, Saphenous vein graft–obtuse margin.
FIGURE 21-2 Unpaced postoperative electrocardiogram.
Atrial sensing and biventricular pacing were demonstrated on the electrogram (Figure 21-3), with a heart rate of 66 bpm and QRS duration of 138 msec.
Chest Radiograph
Findings
A frontal view of the chest demonstrates the heart to be normal in size and configuration (Figure 21-4). Median sternotomy sutures are present in the midline. A right-sided pocket is seen with an ICD and three leads: right atrial lead in the appendage, abandoned right ventricular pacing lead, and ICD lead in the right ventricular apex. The hilar and pulmonary vascular markings are normal, with no parenchymal infiltrates visualized.
The right ventricle appears normal in size and contractility (Figure 21-5). The intraventricular septum moves paradoxically toward the right in systole. The images demonstrate the left ventricle to be moderately dilated, with moderate diffuse hypokinesis. The left ventricular ejection fraction is 31%.
Computed Tomography
Findings
Computed tomography (Figure 21-6) with intravenous contrast was performed to visualize the status and location of previous grafts. The right atrial to left anterior descending, SV OM, and saphenous vein to right coronary artery grafts appear patent. The trajectory of the saphenous vein to obtuse margin graft was such that it allowed for consideration of placement of an epicardial lead on the basilar aspect of the posterolateral wall of the left ventricle. The proximal native coronary arteries are heavily calcified and occluded. There is mild cardiomegaly, with remodeling of the anterior wall of the left ventricle, presumably resulting from previous myocardial infarction.
FIGURE 21-3 Postoperative paced electrocardiogram.
Focused Clinical Questions and Discussion Points
Question
What potential advantages does direct epicardial access offer in contrast to a transvenous lead?
Discussion
Direct epicardial access overcomes the limitations of coronary sinus anatomy in situations in which no veins can be found in the preferred target zone or only inadequate venous branches are found. Visualization of scar tissue and phrenic nerve position avoids left ventricular lead placement at sites of prior myocardial infarction and diaphragmatic capture, respectively.
Question
What is the impact of the patient’s extensive surgical history on left ventricular lead placement?
Discussion
As with any reoperative surgery, adhesions will form between the tissues in the chest cavity. These adhesions can affect visualization of and access to the heart, as well as increase the technical demands of the procedure.
FIGURE 21-4 Chest radiograph on admission.
Question
What must be considered when deciding the location for placement of an epicardial lead?
Final Diagnosis
The final diagnosis in this patient was decreasing left ventricular ejection fraction in the setting of chronic right ventricular pacing, underlying left bundle branch block, and unstable heart failure symptoms.
Plan of Action
The plan for this patient consisted of robotically assisted left thorax approach for placement of left ventricular epicardial leads, lysis of adhesions from previous cardiac surgeries, and tunneling and routing of the two new epicardial leads to the ICD generator located in right chest pocket.
Intervention
Typically, left ventricular lead implantation would be attempted through a transvenous approach; however, a venogram demonstrated very tight stenoses of the subclavian and innominate veins in this patient. This prevented transvenous access for left ventricular lead placement without an extensive revision procedure. Thus a robotic approach was determined to be the optimal platform for left ventricular lead placement. The patient was placed in the right lateral decubitus position with retraction of the left arm cephalad to expose the posterolateral aspect of the left chest. The patient was intubated with a double-lumen endotracheal tube for single-lung ventilation. This allows for a more accurate location of the optimal site for lead placement and mapping.
The lead implantation was achieved through three ports in this case; however, recent advances in technology have shown a single-port approach could potentially be technically feasible.1 Ports for the robotic arms were placed in the fifth (right robotic arm) and ninth intercostal spaces (left robotic arm) between the left-mid or posterior axillary line via a 1-cm incision. An additional 1-cm port in the seventh intercostal space was made at the same level for the robotic three-dimensional HD camera. In traditional left ventricular lead placement, a lateral 8-mm incision in the pacemaker pocket would have been created; however, this was not performed in this patient because his ICD generator was located on the right chest wall and the leads required extensions and tunneling toward the generator pocket from the left side. At the conclusion of the robotic part of the procedure, the patient was repositioned, redraped, and prepped for tunneling of the new left ventricular leads to the right-sided generator.
Through fine, deliberate movement, the robotic arm easily dissected the tenacious adhesions between the left lung and chest wall and from the lung to the pericardium and mediastinum. Lysis of adhesions was achieved using a combination of the robotic spatula and Debakey and Endo scissors.
After all adhesions had been lysed, both the saphenous vein to obtuse marginal graft and the phrenic nerve were visualized and protected throughout the procedure. In reoperative cases, obtaining information regarding the location of previous coronary bypass grafts becomes paramount when planning a minimally invasive approach for left ventricular lead placement. Identifying the trajectory of previous bypass grafts helps avoid intraoperative complications that could potentially become catastrophic. The pericardium was opened lateral to the vein graft and anterior to the phrenic nerve. At this time, adhesions were cleared between the pericardium and the graft, as well as from the pericardium and the posterolateral and basal wall of the heart. The spatula, robotic Debakey forceps, and Endo scissors attachments were used to lyse these adhesions. Two screw-in epicardial leads were placed between the saphenous vein to obtuse margin graft and the second obtuse margin branch over the base of the left ventricle. Pacing thresholds were tested and found to be excellent. The right atrial lead had an intrinsic amplitude of 3.1 mV, impedance of 515 Ω, and a pacing threshold of 2.2 V at 0.5 msec. The right ventricular lead had an impedance of 463 Ω with a pacing threshold of 0.6 V at 0.5 msec. The left ventricular lead had an impedance of 548 Ω with a pacing threshold of 0.6 V at 1 msec and a shock impedance of 46 Ω. The right ventricular lead had an intrinsic R-wave of 17 mV. Because the patient’s generator was in the right chest, the pacing wires were passed through the eighth intercostal space and routed inferiorly toward the costal margin and anterior to the posterior fascia of the abdominal wall and temporarily left in a submuscular plane. At this time, the robotic arms and camera were removed and their respective ports closed in layers.
The patient was then reprepped, draped, and placed in the supine position. The leads were extended and tunneled following a submuscular plane toward the right-sided generator. Once again, the leads tested excellently when reaching the pocket. A second left ventricular lead was placed posterior to the generator to be used as a backup should the primary lead fail. The generator was placed back in its pocket after the new leads had been connected, and the incisions were closed in layers. A chest tube was placed in the left pleural cavity. The patient was extubated in the operating room, and no complications occurred during the surgery or in the perioperative period.
Outcome
Findings
The patient had the chest tube removed on postoperative day 1 and was discharged on postoperative day 2. The pacemaker was set to DDD, with a rate limit of 60 bpm, atrioventricular delay of 160 ms, and left ventricular offset of 0 ms. At early follow-up, the patient described a significant improvement in exercise tolerance and had no heart failure symptoms.
Comments
Patients undergoing robotic left ventricular lead implantation have been shown to have a reduced rate of heart failure, improved quality of life, higher ejection fraction, and reverse ventricular remodeling.3,4 The robotic approach has a high success rate (98%), and reports indicate the leads perform well over the long term, making routine replacements unnecessary.5 The minimally invasive robotic approach has been shown to be successful even in patients who have previously undergone open-heart surgery.5
Robotically assisted surgeries combine the benefits of open and minimally invasive surgery. The DaVinci robotic system (Intuitive Surgical Incorporated, Sunnyvale, Calif.) uses the EndoWrist microinstrument system and three-dimensional images created by the use of two side-by-side videoscopes, providing excellent depth perception. This system is able to mimic the full seven planes of motion of a surgeon’s wrist, thereby merging the unrestricted movement afforded by a sternotomy with the minimally invasive nature of thoracoscopic surgery. The surgeon controls the instruments through a control console away from the surgical field, viewing the surgery through a double eye-piece that provides a real-time, high-definition, magnified endoscopic video feed in real three-dimensional view. The extreme accuracy and precision of the robotic system in such a small space can be attributed to the computer interface, which allows for scaled motion and eliminates tremor. In addition, the three-dimensional endoscopic view makes left ventricular mapping possible.2
Traditionally, left ventricular lead placement has been done using either a minimally invasive thoracotomy or a videoscopic-assisted approach with good results. In our experience, and particularly in reoperative cases, the robotic approach adds a new dimension with regard to ease of instrument manipulation, especially when significant adhesions are present. The addition of three-dimensional imaging, permitting excellent depth perception, is another of the improvements provided by the robotic approach. With an average stay of 48 hours it compares favorably to nonsurgical efforts when those either fail or cannot be attempted in patients in need of chronic resynchronization therapy. After the procedure, the patients enjoy quick return to normal life activities with minimal discomfort. Complications in these cases are avoided by careful patient selection and adequate preoperative imaging studies.
Selected References
1. Choset H., Zenati M., Ota T. et al. Enabling medical robotics for the next generation of minimally invasive procedures: minimally invasive cardiac surgery with single port access. In: Rosen J., Hannaford B., Satava R.M., eds. Surgical robotics. New York: Springer; 2011:257–270.
2. DeRose J.J., Steinberg J.S. Surgical approaches to epicardial left ventricular lead implantation for biventricular pacing. In: Yu C., Hayes D.L., Auricchio A., eds. Cardiac resynchronization therapy. Blackwell: Malden, Massachusetts; 2006:227–236.
3. Derose Jr. J.J., Balaram S., Ro C. et al. Midterm follow-up of robotic biventricular pacing demonstrates excellent lead stability and improved response rates. Innovations (Phila). 2006;1:105–110.
4. Joshi S., Steinberg J.S., Ashton Jr. R.C. et al. Follow-up of robotically assisted left ventricular epicardial leads for cardiac resynchronization therapy. J Am Coll Cardiol. 2005;46:2358–2359.
5. Kamath G.S., Balaram S., Choi A. et al. Long-term outcome of leads and patients following robotic epicardial left ventricular lead placement for cardiac resynchronization therapy. Pacing Clin Electrophysiol. 2011;34:235–240.
