VATS Transmyocardial Laser Revascularization (TMR) For Patients With Endstage Coronary Artery Disease (CAD)

Patient Selection

Figure 1

VATS TMR is performed on patients with class III or IV angina (Canadian Cardiovascular Angina Score) who are not candidates for either coronary artery bypass surgery (CABG) or percutaneous catheter interventions (PCI). The procedure is performed through the left hemithorax with standard thoracoscopic instrumentation. While previous CABG is a common finding in these patients, it is not a contraindication to VATS TMR. Similarly, prior thoracotomy is not a contraindication since the degree of adhesions and the ability to visualize the epicardial surface vary among patients. Current contraindications to performing this procedure include prior left chest radiation therapy, unstable angina, recent myocardial infarction, and uncompensated heart failure. Anticoagulation and antiplatelet therapies are managed as with CABG patients.  Figure 1 demonstrates a coronary angiogram of a typical lesion pattern that is amenable to VATS TMR.

Operative Steps

Positioning and Port Placement

Figure 2

The patient is placed in the left lateral decubitus position with the table break moderately flexed at the patient’s hip level. The left groin is exposed in the unlikely event that femoral – femoral cardiopulmonary bypass becomes necessary.  Rescue defibrillator pads are placed in a similar pattern to when redo sternotomy is planned. Prophylactic antiarrhythmics (i.e. amiodarone or lidocaine) are reserved for patients who have EKG signs of myocardial irritability. While invasive arterial pressure monitoring is used in all patients, pulmonary artery catheters are reserved for patients with ejection fractions less than 40%. Transesophageal echocardiography is performed in all patients to confirm transmurality, which is evidenced by the observation of micro bubbles (Video 1) in the left ventricular chamber.  Single lung ventilation is established and the four thoracoscopic ports are inserted under direct visualization (Figure 2):

1. An 11 mm port at the sixth intercostal space at the level of the posterior axillary line of the left hemithorax. A 10mm zero angle thoracoscope is inserted
2. A 15 mm port at the third intercostal space at the anterior axillary line. This is the
    main operating site through which endoshear and lasing occur
3. An 11m port at the third intercostal space, 1 to 2 cm lateral to the sternal edge. This site is primarily used for grasping.
4. An 11mm or 15mm port at the fifth intercostal space, 1 to 2 cm lateral to the sternal edge. This site is primarily used for diaphragm and/or pericardial retraction, and lasing the anterior surface of the heart.

The pericardium is opened over the area of the left atrial appendage; 2 to 3 cm posterior to the phrenic nerve. Even in patients with prior CABG surgery, there is a residual pericardial space that permits a safe entry point (Video 2). Dissection proceeds superiorly to inferiorly, and posteriorly to anteriorly. A harmonic scalpel may be employed to aid in hemostasis while minimizing cardiac irritability and potential for phrenic nerve injury. Pericardium is dissected in 10 to 20 cm2 increments to provide a workable operative field and to maintain the balance of the pericardial adhesions that assist in stabilization.

Transmural channels are placed approximately 1 cm apart in targeted areas of viable myocardium and are created in groups of three or four, allowing 30 to 60 seconds of recovery to minimize cardiac irritability (Video 3). Handpiece rotation among the ports allows firm and perpendicular contact between the distal tip and epicardium. As dissection proceeds anteriorly, a second pericardotomy, anterior to the phrenic nerve, is frequently necessary to optimize visualization and access. Adjusting the operating table to the “head down” position may aid in visualizing the inferior heart surface.

Figure 3

Similarly, rotating the patient towards the right (towards the surgeon) may improve visualization of the anterior heart. If visualization and/or stabilization are unsatisfactory, an endo stabilizer may be used. The stabilizer is inserted through port 4 and is placed on the apex (Video 4). When operating on the anterior heart, a 30° or flexible thoracoscope is recommended. The sum of these techniques provides substantially improved visualization compared to a limited left anterior thoracotomy. No anticoagulation is administered; as such, bleeding is modest and rarely requires more than a brief period of direct pressure to achieve hemostasis. At the completion of surgery a 19 Fr flexible drain is placed through port #4 (Figure 3). Patients are typically extubated in the operating room

In addition to scheduled ketorolac (15mg IV Q6 x 8 doses) and oral narcotics, postoperative pain is managed by continuous infusion of 0.5% marcain until the day of discharge. Chest tube drainage is typically less than 300 ml, and allows for drain removal on postoperative day 1 when the patients leave the CVICU. Most patients are ready for discharge to home by postoperative days 2 or 3.

Preference Card

1. 90 degree rotating scope
2. Long curved ring clamp
3. 5 mm disposable endoshears
4. Endo Stabilizer (Estech, Danville, CA)
5. Fan retractor
6. PEARL 8.0 Holmium:YAG TMR handpiece (CardioGenesis, Foothill Ranch, CA) [available internationally; currently under investigational use in the US])
7. Stryker Pain Pump (Stryker, Mahwah, NJ)

Tips & Pitfalls

1. Avoid creating more than three or four channels at a time to decrease the likelihood of ventricular dysrhythmias.
2. Maximize the steerable functionality of the laser handpiece to ensure firm device to epicardium apposition.
3. Avoid creating “blind” channels through the pericardium as this practice significantly increases the risk of perforating a coronary vessel or graft.
4. In patients with diffuse pleural adhesions, an extrapleural finger dissection will usually create a satisfactory working space for the camera and instrument dissection.

Results

Figure 4

We have performed over 20 VATS TMR operations over a two year period at the Osceola Regional Medical Center. For the last seven operations we have used the PEARL 8.0 handpiece (Figure 4), which has made this a less technically demanding operation. There have been no conversions to thoracotomy, intraoperative surgical or hospital mortality. Serious adverse events are uncommon, with one (5%) patient requiring drainage of a left hemithorax.  Similarly, post thoracotomy  pain syndrome has occurred in only a single patient (5%) with a history of two prior CABGs. A learning curve exists (especially in patients with prior CABG) and significant progress can be expected after approximately five procedures. Operative times are typically less than two hours in patients with prior CABG, and about one hour in primary cases [1].  Mean follow up is approximately eight months during which time angina relief has been excellent. Eighteen patients (90%) patients have experienced a drop of two or more angina classes, and 5 patients (25%) are angina free at current follow up. These results compare favorably to the multicenter trial by Allen et al where a left anterolateral thoracotomy was the predominant approach [2]. The great majority of patients resume normal activities within 10 to 14 days.

References

1. Allen GS. Mid-term results after thoracoscopic transmyocardial laser revascularization. Ann Thorac Surg. 2005;80:553-8.
2. Allen KB, Dowling RD, Fudge TL, et al. Comparison of transmyocardial revascularization with medical therapy in patients with refractory angina. New Engl J Med 1999;341:1029-36.