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Minimally Invasive Direct Coronary Artery Bypass

Marco Zenati, MD
Ory Wiesel, MD
VA Boston Healthcare System
  1. Introduction
    1. Anesthesia
      • The patient is kept on his preoperative antiplatelet therapy. Standard premedication is given at the preoperative holding area. Invasive (arterial line, central venous line, transesophageal echocardiography) and noninvasive (pulse oximetry, Foley) monitoring modalities are the same as for standard coronary artery bypass graft surgery. A Swan Ganz catheter is not used as a routine. Temperature monitoring is of high importunacy and is monitored by Foley catheter probes. If needed, epidural or paravertebral block (T2-T3) can be done prior to induction.
      • The procedure is facilitated by one lung ventilation and the patient is intubated with double-lumen endotracheal tube. Bronchial blocker is a reasonable alternative as long as the blocker provides adequate lung isolation by bronchoscopy.
      • Anticoagulation during the procedure is achieved with intravenous heparin (goal activated clotting time >300 seconds). At the end of the procedure, heparin is half- reversed with protamine. A cell saver is used to collect and recycle shed mediastinal blood.
    2. Patient Positioning
      • The patient placed supine with his left arm tucked. Longitudinal roll is placed under the left chest. Alternatively, slight tilt (15°) horizontally to the right will assist with exposure. External defibrillator pads are placed in the left infrascapular region and the right subclavicular region.
      • The patient is prepped including the lower extremities (in case of conversion and need for vein harvest) and both groins and the sternum are exposed below the drapes.
  2. Exposure to Identify Target
    1. Perform Left 3 Inch Mini Thoracotomy in the 5th Intercostal Space
      • A 5cm skin incision is made usually in the 5th intercostal space (sometimes 6th space) just below the mammary fold. The incision is started at mid-clavicular line and extended medially.
      • Some authors prefer the 4th intercostal space; however we found that the 5th space allows better exposure of the mid-portion of the LAD and wider anastomosis target. It also enables better exposure to the mammary artery providing longer harvested artery.
      • Extreme caution should be practiced to avoid injury to the LIMA with medial extension of the incision. The skin incision is usually smaller than the intercostal dissection.
      • The left lung is isolated by the anesthesiologist, the pleural space is opened, and a LIMA-lift retractor (Medtronic INC, Minneapolis, MN) is placed in the wound.
      • A rul-tract retractor based on the left rails of the table with a hook is attached to the superior blade of the LIMA-lift, allowing optimal visualization of the medial portion of the sternum for better LIMA harvest.
    2. Enter 5th Intercostal Space
    3. Mobilize Fat Pad
    4. Open Pericardium
      • The LIMA-lift retractor is exchanged with a dedicated MIDCAB retractor.
      • The anterior pericardium is opened over the LAD. The pericardial incision is carried down to the apex of the heart. Pericardial stay sutures are placed on both edges of the incision, as needed.
  3. Assessment of Target
    1. Assess Left Anterior Descending Coronary Artery Quality and Size
      • The LAD is identified parallel to the sternum to the right of the apex.
    2. Identify Diagonal Branch
      • The Diagonal artery (which is sometime mistakenly identified as the LAD) is often seen coursing parallel to the incision and toward the apex.
  4. Harvest Left Internal Mammary Artery (LIMA)
    1. Identify Lateral Mammary Vein
    2. Divide Fascia
      • The endothoracic fascia is identified and dissected.
    3. Identify Mammary Artery
      • The fat pad overlying the LIMA is cleaned.
    4. Expose Distal Aspect of Mammary
      • The LIMA is dissected, skeletonized to achieve optimal length for LAD anastomosis.
      • The LIMA is dissected proximally to its origin from the left subclavian vessels (usually up to 1st intercostal space), whereas the caudal extent of LIMA dissection is usually at the level of the 6th intercostal space proximal to the bifurcation between the pericardio-phrenic and the superior epigastric artery.
    5. Insert Lima Lift
    6. Incise Intrathoracic Fascia over the Mammary Artery for Hemiskeletonization
    7. Modify Placement of Lima Lift
    8. Optimize Exposure through Small Adjustment on LIMA Lift Retractor
    9. Divide Mammary Artery
      • Once the patient is heparinized, the artery is ligated and divided distally.
      • 5cc of papaverine (1mg/ml) solution are sprayed over the mammary to allow pharmacologic dilation of the conduit.
      • A bull-dog clamp is placed at the distal end of the LIMA to allow gentle distention under physiological pressure.
    10. Test Flow of Conduit
  5. Anastomosis
    1. Tack Mammary to Edge of Incision
    2. Prepare Mammary
    3. Proximal Occlusion of Left Anterior Descending Coronary Artery
    4. Stabilize LAD
      • We use a pressure stabilizer attached to the MIDCAB retractor and placed parallel to the LAD and pushed down gently against the septum.
      • The LIMA is cleaned and prepared in the usual fashion and beveled at its distal part.
      • The target LAD area is chosen and proximal snare is placed only proximally to the chosen arteriotomy site.
    5. Perform End-to-Side LIMA to LAD Anastomosis Using Separate Heel-and-Toe Technique with 8-0 Prolene
      • The surgeon’s assistant uses a Blower-mister device to assist with exposure.
    6. Arteriotomy
      • 1cm arteriotomy is carefully done.
    7. Place Intracoronary Shunt of Appropriate Size
      • An appropriately sized intra-coronary shunt is used to avoid ischemic time during the anastomosis and minimize blood loss.
    8. Perform Anastomosis
    9. Parachute the Mammary Artery Down
    10. Complete Anastomosis
    11. Retrieve Shunt
    12. Open Mammary Artery
  6. Graft Patency Verification with Transit-Time Flowmeter
      • The bulldog clamp on the LIMA is released.
      • Flow is checked with Flow-meter.
      • Punctual arterial bleeds repaired.
      • After revascularization, heparin is reversed with Protamine.
    1. Reapproximate Mediastinal Fat over Pericardiotomy
      • The pericardial sac is loosely re-approximated with 2-0 Vicryl sutures.
      • Care should be taken at this point not to exert traction on the LIMA.
    2. Perform Intercostal Nerve Cryoablation for Pain Control
      • An intercostal rib block (rib 4-6) is usually done with 0.5% bupivacaine solution; alternatively a intercostal nerve cryoablation may be performed.
    3. Insert Chest Tube
      • Straight chest tube placed below the incision and secured.
    4. Wound Closure
      • The ribs are re-approximated and the lung is allowed to re-inflate.
      • The wound is closed in layers in the usual manner.
  7. Closing Remarks
    1. Postoperative care
      • The goals of post-operative care are early mobilization and pain control.
      • Most of the patients are extubated in the operating room and transferred to the Intensive care unit for overnight observation.
      • Antiplatelet therapy is continued, and pain is controlled with the combination of NSAIDs Paracetamol and minimal Opiates as needed.
      • Intravenous fluids are restricted and the patients are advanced to clear and then regular diet usually on postoperative day 1st and 2 respectively.
      • Early ambulation is crucial and the arterial line, central line, and chest tube are usually taken out in post-operative day 1.
      • Patients are discharged home on postoperative day 4 or 5 ambulating with oral pain control.