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Departments of *Anesthesiology and Cardiothoracic Surgery, Columbia Presbyterian Medical Center, New York, New York
Address correspondence and reprint requests to Dr. Berend Mets, Associate Professor of Clinical Anesthesiology, Columbia Presbyterian Medical Center, 630 W. 168th St., P&S Box 46, New York, NY 10032-3784. Address e-mail to bm44{at}columbia.edu
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Abstract |
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IMPLICATIONS: We describe the anesthetic management of two patients who underwent successful mitral valve repair with use of a robot-assisted cardiac surgical technique. We describe the robot used, as well as the surgical procedure, and highlight aspects of the anesthetic management, in particular the need for one-lung ventilation and the utility of transesophageal echocardiography.
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Introduction |
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The da VinciTM Surgical System (Intuitive Surgical, Mountain View, CA) consists of a surgeon’s console (Fig. 1), a patient-side cart, a high-performance vision system, and instruments (Fig. 2). Using the da Vinci Surgical System, the surgeon operates while seated comfortably at a console viewing a three-dimensional image of the surgical field. The surgeon’s fingers grasp the instrument controls below the display, with wrists naturally positioned relative to his or her eyes. The robotic technology seamlessly translates the surgeon’s movements into precise, real-time movements of the surgical instruments inside the patient. The surgeon uses a microphone speaker to direct another surgeon positioned at the surgical field, directing the tasks of positioning a sucker to maximize visibility.
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Case Report |
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The patient weighed 80 kg, had never experienced surgery, and was not known to be allergic to any medications. Before the operation, his hematocrit was 45.8%, blood urea nitrogen was 21 mg/dL, and plasma creatinine was 1.5 mg/dL; coagulation values were within the reference range.
Case 2
The patient, a 58-yr-old Caucasian man with severe MR and a history of mitral valve prolapse, hypertension, and gastrointestinal bleeding of unknown etiology, was being treated with lisinopril. He was found to have an aberrant right subclavian artery on computed axial tomogram of the chest, sinus rhythm with first-degree atrioventricular block, and left ventricular hypertrophy on electrocardiogram. Transesophageal echocardiogram (TEE) revealed severe MR from prolapse and flail of the posterior mitral leaflet, with normal left ventricular function. Cardiac catheterization revealed a pulmonary artery pressure of 35/16 mm Hg and a cardiac output of 6.4 L/min.
He weighed 91.6 kg, had had general anesthesia in the past without complications, and was not known to be allergic to any medications. Before surgery his hematocrit was 40.8%, blood urea nitrogen was 19 mg/dL, and plasma creatinine was 1.0 mg/dL, with a normal coagulation profile.
After placement of standard monitors and a radial arterial line, both patients were anesthetized with a combination of midazolam, etomidate, fentanyl, and isoflurane and paralyzed with rocuronium for endotracheal intubation. To enable subsequent one-lung anesthesia, a left-sided double-lumen endotracheal tube was placed and its appropriate position confirmed with a fiberoptic bronchoscope. A TEE probe (M2424A Ultrasound system; Hewlett-Packard, Andover, MA) was placed to monitor valve repair and left ventricular function and to guide later placement of the superior vena cava (SVC) and inferior vena cava (IVC) cannulae and to confirm coronary sinus cannulation for retrograde cardioplegia administration (vide infra). Then a 9F introducer was placed into the left internal jugular vein and an 8F pulmonary artery catheter inserted.
A 17F Biomedicus (Eden Prairie, MN) cannula was then placed into the SVC via the right internal jugular vein, percutaneously, by the anesthesiologist, who used a Seldinger technique. At the time of placement, the cannula was flushed with 5000 U of heparin, and a continuous flush with 5000 U of heparin in 1 L of normal saline was used to ensure its patency. The cannula and tubing were then stabilized by anchoring to the patient’s head with a crepe bandage. The TEE was used to image the right atrium (RA) and the SVC to confirm initial appropriate location of the Seldinger wire and subsequent placement of the cannula at the SVC/RA junction (midesophageal bicaval view at 90°).
Next, the patients were positioned in a modified left lateral decubitus position, with their hips flat and the right arm elevated on a padded support bar. Intraoperative TEE evaluation (Fig. 3) in Case 1 revealed severe MR (4+) with a flail posterior leaflet and an eccentric jet over the abnormal leaflet and a mean pressure gradient (MPG) of 4.4 mm Hg. All other valves were normal. The left ventricular ejection fraction was 60%, with no regional wall motion abnormality.
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After the right femoral vessels were exposed and single (left)-lung ventilation established, the chest cavity was entered and the heart exposed after opening of the pericardium by means of a 5-cm incision along the fifth rib, lateral to the midclavicular line. The pericardium was then anchored to the chest wall by placement of stay sutures. Then, after activated coagulation time-guided heparinization, the femoral artery and vein were cannulated with a 24F Bard cannula (C. R. Bard Inc., Haverhill, MA) and a 21F Biomedicus cannula, respectively. Appropriate location of the IVC cannula was confirmed within the RA by using TEE (midesophageal bicaval view at 90°). In addition, TEE visualization was used to guide and confirm retrograde coronary sinus cannula placement.
Cardiopulmonary bypass (CPB) was established, with venous drainage from both the femoral (IVC) and internal jugular (SVC) cannulae and an anterograde cardioplegia catheter. The transthoracic aortic cross-clamp (Cardiovasive Chitwood Debakey clamp) was passed through a stab wound in the right axilla and applied to the ascending aorta. Cold blood (4:1) cardioplegia was given anterograde and retrograde. Small (8-mm) incisions were made in the third and fourth intercostal space, lateral to the minithoracotomy incision. The right and left robotic arms (da Vinci robotic system) (Fig. 2) were passed through the port sites, and the robotic endoscopic camera was positioned in the medial aspect of the minithoracotomy incision. In Cases 1 and 2, mitral valvuloplasty (quadrangular resection, Cosgrove No. 30 ring) was performed with robotic assistance.
After completion of the repair, valvular function was assessed to exclude significant regurgitation and then, by using one-lung ventilation, the patients were weaned from CPB after inotropic support was instituted with norepinephrine (both cases) and dobutamine infusion (0.5 µg · kg-1 · min-1) (Case 1). Post-CPB arterial blood gases on a fraction of inspired oxygen of 1.0 were the following for Case 1: arterial pH, 7.30; PaCO2, 49 mm Hg; PaO2, 138 mm Hg; base excess, -2 mEq/L; HCO3, 24 mEq/L; and oxygen saturation, 99%. In Case 2 they were arterial pH, 7.28; PaCO2, 49 mm Hg; PaO2, 408 mm Hg; base excess, -3 mEq/L, HCO3, 23 mEq/L; and oxygen saturation, 100%. Lung-recruitment maneuvers (temporarily inflating the nondependent lung) were needed to maintain adequate oxygen saturation when coming off CPB in both cases. The total bypass time was 4 h exactly and 4 h 42 min, whereas cross-clamp time was 2 h 49 min and 3 h 7 min for Case 1 and 2, respectively.
After separation from CPB, TEE evaluation demonstrated in Case 1 an absence of MR (Fig. 3), a normal MPG (4 mm Hg), and no systolic anterior motion (SAM) of the anterior mitral leaflet. In Case 2 we found no MR and an MPG of 4 mm Hg, with minor SAM that did not require intervention.
The 17F SVC cannula was removed after chest closure, when activated coagulation time had been confirmed to be back to baseline after protamine reversal. Digital pressure was held at the cannulation site in both patients until hemostasis was secured. After this, a careful assessment of facial edema was made as to the feasibility of replacing the double-lumen tube (DLT) with a single-lumen endotracheal tube. We then replaced the DLT by inserting a Cook airway exchange catheter through the tracheal lumen and withdrawing the DLT and railroading a single-lumen tube with an 8-mm internal diameter to ensure that we did not "lose" the airway.
Both patients were tracheally extubated on postoperative Day 1. The postoperative course of Case 1 was complicated by the development of atrial fibrillation on postoperative Day 2, and the patient was started on heparin initially and was discharged on coumadin on postoperative Day 6. The postoperative course of Case 2 was complicated by a small pleural effusion. He was discharged on postoperative Day 5.
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Discussion |
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The patients selected for this procedure were in the age group 18–80 years, had isolated MR without mitral stenosis, with MR, the result of posterior leaflet pathology. The key issue that the anesthesiologist may face in using this technique is maintaining stable hemodynamics and oxygenation in a patient with severe MR (with possible cardiac decompensation) during both the induction and maintenance of anesthesia as well as during one-lung ventilation while preparing the patient to go on CPB for the definitive mitral valve repair. Further concerns are the need to separate from CPB by using only single-lung ventilation after a potentially prolonged CPB time with possible pulmonary compromise (4).
One-lung ventilation is necessary because the pericardium is tethered to the chest wall with stay sutures, and ventilation of the corresponding nondependent lung would cause lung laceration by the stay sutures as the lung inflates. Furthermore, one-lung ventilation also helps to provide the surgeons a clear view of the operative field while the patient comes off CPB, because at this point it is imperative to identify and control any bleeding. To ensure adequate oxygenation before and immediately after CPB, we use intermittent insufflation of the nondependent lung, sufficient to maintain oxygen saturation of 95%–100%, but do not inflate this lung to the extent that the lung will be damaged by the stay sutures.
Thus, we believe that lung isolation is best assured by using a DLT, even though a Univent tube (Fuji Systems Co., Tokyo, Japan) or temporary isolation of one lung by using a bronchial blocker would avoid the need to change to a single-lumen tube at the end of the operation. This is because neither the Univent tube nor a bronchial blocker technique allows intermittent nondependent lung inflation to combat desaturation. Thus, the use of a DLT appears most appropriate in these patients (5). Nevertheless, replacing the DLT with a single-lumen tube at the end of surgery to facilitate intensive care unit management may be complicated by the profound facial and upper-airway edema that is often present. We facilitated the endotracheal tube changeover with the use of a Cook catheter. However, occasionally we do leave the DLT in place, especially when we anticipate that the patient will be extubated very early in the intensive care unit.
TEE is crucial for the continuous monitoring of cardiac function and is key to proper placement of the femoral (IVC) and internal jugular (SVC) cannulae. At a later stage, the TEE is important for the insertion of the coronary sinus catheter, because the surgeon is blind to the continued appropriate positioning of these cannulae because of the limited surgical access. Finally, it is essential to assess the quality of the mitral valve repair and to exclude significant repair-induced mitral stenosis or the development of SAM of the mitral valve. In these patients, a pulmonary artery catheter is placed via the left internal jugular vein, because the right internal jugular vein is needed for placement of the Biomedicus SVC cannula.
The 17F Biomedicus arterial cannula is placed into the SVC via the right internal jugular vein by the Seldinger technique with TEE guidance. The SVC cannula is required to allow for venous drainage from the upper part of the body and stents the SVC during manipulation of the heart. The cannula used is pre-heparinized with 5000 U of heparin and a continuous flushing device attached to infuse a heparin saline infusion (2 U/mL) to avoid clot formation in the cannula. During CPB, the central venous pressure should be read from the sheath catheter rather than intracardiac (central venous pressure) to allow for early detection of venous congestion in the upper part of the body.
Patient positioning involves a modified left lateral decubitus position, with the lower part of the body flat and the right arm elevated on a padded support bar; hence, left radial arterial monitoring appears appropriate. Maintenance of anesthesia for these procedures is guided by the fact that early extubation after these nonsternotomy procedures would appear to be desirable and readily achievable with minor tailoring of the traditional cardiac anesthetic (6,7). Maintenance usually consists of isoflurane or another inhaled drug in a small dose, a nondepolarizing muscle relaxant of moderate duration, and anesthesia adjuncts as needed.
In summary, we have presented two patients who had successful mitral valve repair with use of robotic surgical techniques. Anesthetic management of these patients may be challenging because these patients may be hemodynamically compromised yet require prolonged periods of one-lung ventilation before and when coming off CPB. Further, percutaneous SVC cannulation for venous drainage to achieve CPB is performed (by the anesthesiologist) and TEE used to ascertain appropriate placement of this and other cannulae for CPB. TEE evaluation of the mitral valve repair, as well as for the absence of significant stenosis and SAM, is crucial during this procedure. Finally, a safe technique for exchanging the DLT required during the operation with a single-lumen tube for postoperative ventilation must be used because of the significant facial edema associated with this surgical technique.
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This article has been cited by other articles:
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  L. W. Nifong and W. R. Chitwood Jr. Challenges for the Anesthesiologist: Robotics? Anesth. Analg., January 1, 2003; 96(1): 1 - 2. [Full Text] [PDF]
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