Prospective clinical trial of robotically assisted endoscopic coronary grafting with 1-year follow-up.

OBJECTIVE: To follow up in prospective fashion patients with coronary artery anastomoses completed endoscopically with robotic assistance. The robotic system was evaluated for safety and its effectiveness in completing microsurgical coronary anastomoses. SUMMARY BACKGROUND DATA: Recently there has been an interest in using robotics and computers to enhance the surgeon's ability to perform endoscopic cardiac surgery. This interest has stemmed from the rapid advancement of technology and the desire to make cardiac surgery less invasive. Using traditional endoscopic instruments, it has not been possible to perform coronary surgery. METHODS: Nineteen patients underwent robotically assisted endoscopic coronary artery bypass grafting of the left internal thoracic artery (LITA) to the left anterior descending artery (LAD). Two robotic instruments and one endoscopic camera were placed through three 5-mm ports. A robotic system was used to construct the LITA-LAD anastomosis. All other required grafts were completed by conventional techniques. RESULTS: Seventeen LITA-LAD grafts (89%) had adequate intraoperative flow. The mean LITA-LAD graft flow was 38.5 +/- 5 mL/min. At 8 weeks, LITA-LAD grafts were assessed by angiography and showed 100% patency with thrombolysis in myocardial infarction (TIMI) I flow. At a mean follow-up of 17 +/- 4.2 months, all patients were NYHA class I and there were no adverse cardiac events. CONCLUSIONS: The results from the first prospective clinical trial of robotically assisted endoscopic coronary bypass surgery in the United States showed favorable short-term outcomes with no adverse events. Robotic assistance is an enabling technology allowing the performance of endoscopic coronary anastomoses.

Potassium channel openers: are they effective as pretreatment or additives to cardioplegia?

BACKGROUND: This study was designed to test the hypothesis that the potassium channel opener pinacidil (Pin) as a pretreatment (PT) agent or additive to St. Thomas' solution (StT) could enhance myocardial protection. METHODS: In a parabiotic rabbit Langendorff model, 36 hearts underwent global normothermic ischemia (1 hour) followed by reperfusion (30 minutes). Cardioplegia (50 mL, every 20 minutes) consisted of: StT; PinPT/StT, where Pin PT preceded StT arrest; Pin alone; Pin in StT (Pin/StT); and Pin in low potassium StT. Systolic function after reperfusion (percent recovery of developed pressure) and compliance (diastolic slope from pressure-volume relationship) were measured. RESULTS: There was no significant difference between StT and PinPT/StT in percent recovery of developed pressure (51.54% +/- 3.5%, 42.17% +/- 4.0%, respectively) or compliance. Likewise, no significant differences occurred between Pin, StT, Pin/StT, and Pin in low potassium StT in percent recovery of developed pressure (58.99% +/- 4.8%, 51.54% +/- 3.5%, 53.09% +/- 3.2%, 66.43% +/- 7.3%, respectively) or compliance. CONCLUSIONS: Pin is as effective a cardioplegic agent as StT; however, its use as a pretreatment or additive to traditional and Pin in low potassium StT provided no additional benefit in functional recovery.

Cardioplegia-induced cell swelling: prevention by normothermic infusion.

BACKGROUND: Previous work has shown significant swelling of isolated rabbit myocytes exposed to cold hyperkalemic cardioplegia; however, the effect of warm hyperkalemic cardioplegia on myocyte volume is unknown. This study examined the effect of warm hyperkalemic cardioplegia (St. Thomas' solution) on myocyte volume. METHODS: Myocytes were enzymatically isolated and placed on an inverted video microscope. Tyrode's solution (37 degrees C) was infused for 10 minutes to establish baseline cell volumes. Subsequently, either the control Tyrode's or St. Thomas' was infused either at 37 degrees C and 9 degrees C respectively (n = 5 for all groups) for 20 minutes, followed by a 30-minute reperfusion with 37 degrees C Tyrode's. Cell volume was determined from cell images captured every 5 minutes. RESULTS: Myocyte swelling occurred rapidly on exposure to cold St. Thomas' solution to a maximum of 9.8 +/- 2.1% (p < 0.001). In contrast, myocytes exposed to warm cardioplegia did not show any volume changes during exposure to cardioplegia. However, upon reexposure to Tyrode's, these cells showed shrinkage below their baseline volume (p < 0.001). CONCLUSIONS: The cell swelling associated with hypothermic cardioplegia is prevented by normothermic infusion.

Robotically assisted coronary artery bypass grafting: a prospective single center clinical trial.

AIM: This prospective study was performed as a Phase 1 Food and Drug Administration clinical trial to assess the safety and feasibility of robotically assisted coronary artery bypass grafting (CABG). METHODS: Eighteen patients undergoing elective CABG were enrolled in this study. Full sternotomy was performed in 17 of 18 patients, while cardiopulmonary bypass and cardioplegic arrest was used in all cases. Robotically assisted CABG of the left internal thoracic artery (LITA) to the left anterior descending artery (LAD) was performed through three ports using a robotically assisted microsurgical system. Conventional techniques were used to perform all other grafts. Blood flow in the LITA graft was measured in the operating room, and when necessary, angiography was performed. Six weeks after the operation, all patients underwent selective coronary angiography of the LITA graft. RESULTS: Robotically assisted coronary artery anastomoses were successfully completed in all patients. Blood flow through the LITA graft was adequate in 16 of 18 patients (89%). The two inadequate grafts were revised successfully by hand. Six weeks after the operation, angiography demonstrated a graft patency of 100% (13 of 13). Mean follow-up has been over 190 days. All patients remain New York Heart Association Angina Class I. CONCLUSION: Robotic assistance represents an enabling technology that may allow the surgeon to perform endoscopic coronary artery anastomoses. Further clinical trials are needed to explore the clinical potential and value of robotically assisted CABG.

Initial United States clinical trial of robotically assisted endoscopic coronary artery bypass grafting.

OBJECTIVES: With traditional instruments, endoscopic coronary artery bypass grafting has not been possible. This study was designed to determine the clinical feasibility of using a robotically assisted microsurgical system to create endoscopic coronary anastomoses. METHODS AND RESULTS: Ten patients underwent endoscopic coronary artery bypass grafting of the left internal thoracic artery to the left anterior descending artery. Subxiphoid endoscopic ports (2 for instruments, 1 for a camera) were placed, and a robotic system was used to perform the left internal thoracic artery-left anterior descending artery bypass graft. Conventional techniques were used to perform the other grafts. Blood flow through the left internal thoracic artery graft was measured in the operating room and was adequate in 8 of 10 patients. The 2 inadequate grafts were revised successfully by hand. Six weeks after the operation, selective coronary angiography demonstrated a graft patency of 100% (8/8). There were no technical failures of the robotic system. The only postoperative complication was mediastinal hemorrhage in 1 patient. CONCLUSIONS: This pilot study demonstrates the feasibility of robotically assisted endoscopic coronary artery bypass grafting.

Computer-assisted endoscopic coronary artery bypass anastomoses: a chronic animal study.

BACKGROUND: With traditional instruments, endoscopic coronary artery bypass grafting (ECABG) has not been possible. This study was designed to determine the feasibility of using a robotically-assisted microsurgical system to perform ECABG in a chronic animal model. METHODS: Nine calves were placed on cardiopulmonary bypass after harvesting the left internal mammary artery (LIMA). Subxiphoid endoscopic ports (2 instrument, 1 camera) were placed, and a robotic system was used to perform ECABG between the LIMA and left anterior descending coronary artery. LIMA graft flow (LIMAQ) was measured. Animals were sacrificed at 1 month, and hearts underwent angiographic and histologic analyses. RESULTS: Acute graft patency was 89% (8/9). Two animals died suddenly within the first 48 hours. There was no significant difference in mean acute and chronic (n = 6) LIMAQ (40.9+/-4.7 and 38.5+/-5.0 ml/min, respectively). Survivors had an angiographic patency rate of 100% (6/6), confirmed by histology. CONCLUSIONS: This study shows that ECABG is feasible in a chronic animal model with excellent results.

Potassium-channel opener cardioplegia is superior to St. Thomas' solution in the intact animal.

BACKGROUND: In isolated hearts, the potassium-channel opener pinacidil is an effective cardioplegic agent. This study tested the hypothesis that pinacidil is superior to St. Thomas' solution in the more clinically relevant intact animal. METHODS: Sixteen pigs were placed on full cardiopulmonary bypass. Hearts underwent 2 hours of global ischemia (10 degrees to 15 degrees C). Either St. Thomas' or 100 micromol/L pinacidil was administered every 20 minutes (10 mL/kg). Preischemic and postreperfusion slopes of the preload-recruitable stroke work relationship were determined. Changes in myocardial adenine nucleotide levels and cellular ultrastructure were analyzed. RESULTS: Pinacidil cardioplegia resulted in an insignificant change in the slope of the preload-recruitable stroke work relationship (40.6+/-2.1 mm Hg/mm before ischemia and 36.5+/-3.7 mm Hg/mm after ischemia; p = 0.466). In contrast, St. Thomas' solution resulted in a significant decrease in the slope after reperfusion (34.3+/-5.5 mm Hg/mm and 13.5+/-2.3 mm Hg/mm; p = 0.003). Adenine nucleotide levels, myocardial tissue water, and ultrastructural changes were similar between groups. CONCLUSIONS: Pinacidil ameliorated myocardial stunning associated with traditional hyperkalemic cardioplegia without causing significant differences in cellular metabolism.

2,3-Butanedione monoxime cardioplegia: advantages over hyperkalemia in blood-perfused isolated hearts.

BACKGROUND: 2,3-Butanedione monoxime (BDM) has been shown to possess cardioprotective properties related to the inhibition of cross-bridge force development, the reduction of myofilament Ca2+ sensitivity, and the attenuation of intracellular Ca2+ transients. This study tested the hypothesis that cardiac arrest achieved with BDM would be as effective as that achieved with St. Thomas' solution (StT). METHODS: Isolated rabbit hearts, studied on a blood-perfused Langendorff column, underwent 1 hour of ischemia (37 degrees C) and 30 minutes of reperfusion. Cardioplegia was administered every 20 minutes in the form of (1) Krebs-Henseleit solution only (control), (2) 20 mmol/L of BDM, or (3) StT. Recovery of developed pressure, atrioventricular activation times, and tissue water content were measured. RESULTS: Recovery of developed pressure for the control, BDM, and StT groups was 44%+/-3% (p<0.05 versus BDM and StT), 57%+/-5%, and 62%+/-4%, respectively. Atrioventricular activation times were significantly prolonged in the control group (42+/-15 ms, p = 0.042) and the StT group (26+/-9 ms, p = 0.034), but not in the BDM group (14+/-8 ms). Tissue water content after reperfusion was 80%+/-0.4%, 80%+/-0.2%, and 76%+/-1.0% (p<0.05 versus control) in the control, StT, and BDM groups, respectively. CONCLUSIONS: 2,3-Butanedione monoxime was as effective as StT in protecting the myocardium. Unlike StT, BDM ameliorated myocardial edema and atrioventricular conduction delay after reperfusion.

Robotically-assisted coronary artery bypass surgery: moving toward a completely endoscopic procedure.

BACKGROUND: Endoscopic coronary artery bypass grafting (ECABG) has not been possible with traditional techniques. This report details our animal experience determining the feasibility of using a robotically-assisted microsurgical system to perform ECABG. METHODS: Following preliminary work using a cadaveric pig heart model, acute and chronic animal studies were performed. Calves were placed on cardiopulmonary bypass after the left internal mammary artery (LIMA) was harvested. Subxiphoid endoscopic ports (2 instrument, 1 camera) were placed and a robotic system was used to perform ECABG between the LIMA and left anterior descending coronary artery. LIMA graft flow (LIMAQ) was measured, and excised hearts underwent angiographic and histologic analyses. RESULTS: All anastomoses were successfully completed in both the acute and chronic studies (mean time of 33.9 +/- 1.9 and 33.2 +/- 3.4 minutes, respectively). Angiographic patency was 100% in both the acute (8/8) and chronic (6/6) studies, which was confirmed by histology. In the chronic study, there was no difference in LIMAQ between intraoperative and autopsy measurements. CONCLUSIONS: This study shows that ECABG is feasible in an animal model with excellent results. The FDA has recently given approval for clinical trials of this new technology.

Computer-assisted endoscopic coronary artery bypass grafting: the penn state experience.

The introduction and widespread acceptance of minimally invasive techniques have revolutionized surgical practice in many disciplines over the last two decades. Endoscopic operations have been shown to reduce patient morbidity and provide a more rapid return to work. Until recently, endoscopic approaches have had little impact on the field of cardiac surgery. Endoscopically-sutured coronary anastomoses have not been possible with conventional endoscopic instruments, due in part to their length and imprecision.

Robotically assisted microsurgery for endoscopic coronary artery bypass grafting.

BACKGROUND: As minimally invasive approaches to cardiac surgery have expanded, a significant number of limitations have become apparent, particularly the lack of adequate precision with standard endoscopic instruments. We hypothesized that the use of robotics would eliminate some of these limitations. METHODS: Twenty-five coronary anastomoses on an isolated porcine heart, using an arterial conduit to the left anterior descending artery, were performed endoscopically with a microsurgical robotic system. Sophisticated robotic engineering was used to control modified endoscopic instruments under direct surgeon control. Computer tremor elimination and motion scaling allowed for precise maneuvering. An arteriotomy was placed in the left anterior descending artery, and an arterial conduit was positioned for anastomosis. The camera and port sites were placed 90 degrees from the long axis of the arteriotomy. A 7-0 Prolene (Ethicon, Somerville, NJ) suture was used to perform the anastomosis in a continuous fashion, begun at the 12 o'clock position and continued counterclockwise. After completion of half of the anastomosis, the conduits were pulled down and the final sutures were placed. The sutures were tied intracorporeally and the procedure was completed. RESULTS: The 25 conduits were successfully completed and showed good probe patency. Average time for completion of the anastomosis was 31.7 +/- 2.0 minutes. Appropriate port placement and orientation, and stabilization of the conduits were critical. The lack of tremor and motion scaling allowed for the precise movements needed to complete an endoscopic microvascular anastomosis. CONCLUSIONS: Coronary artery anastomoses are technically feasible with use of robotic instrumentation. This technology may enable the development of a truly endoscopic approach to bypass surgery.

Advantages of continuous hyperpolarized arrest with pinacidil over St. Thomas' Hospital solution during prolonged ischemia.

OBJECTIVE: The potassium channel opener, pinacidil, has been shown to be an effective cardioplegic agent over short periods of ischemia. However, clinical settings typically involve longer ischemic periods. This study tested the hypothesis that myocardial protection with a potassium channel opener is feasible during prolonged periods of arrest and is comparable with the traditional St. Thomas' Hospital solution. METHODS: With a blood-perfused, isolated rabbit heart model, hearts underwent 1 hour of global normothermic ischemia followed by 30 minutes of reperfusion. During ischemia, three different cardioplegic solutions were administered either intermittently by infusion every 20 minutes or as continuous low-flow cardioplegia (150 ml total volume in all groups): (1) Krebs-Henseleit solution alone (control), (2) Krebs-Henseleit solution + pinacidil (50 micromol/L), or (3) St. Thomas' Hospital solution. Initial potassium channel opener infusions contained 5 mmol/L procaine. Postreperfusion systolic function (percent of developed pressure) was measured. Compliance changes were integrated from the end-diastolic pressure/volume relationships. RESULTS: For intermittent cardioplegia, only St. Thomas' Hospital solution improved function (62.5% +/- 4.0%) versus control (43.6% +/- 3.3%,p < 0.001). However, with continuous cardioplegia, only pinacidil (75.6% +/- 4.8%) exceeded control (62.7% +/- 2.2%, p < 0.001) and was significantly better than St. Thomas' Hospital solution. Compared with the intermittent control group, all other groups showed significant preservation of preischemic diastolic properties. CONCLUSIONS: Myocardial protection during a longer, more clinically relevant ischemic period is feasible with a potassium channel opener only when it is given continuously. Continuous low-flow pinacidil cardioplegia was superior to St. Thomas' Hospital solution given either as an intermittent or continuous infusion.

Prevention of cell swelling with low chloride St. Thomas' Hospital solution improves postischemic myocardial recovery.

OBJECTIVE: In isolated myocytes cardioplegia-induced cell swelling can be prevented by lowering the KCl product by replacing Cl- with an impermeant ion. This study tested the hypothesis that Cl- substitution in St. Thomas' Hospital cardioplegic solution would result in superior myocardial protection in the intact, blood-perfused heart. METHODS: Using a parabiotic, isolated rabbit heart Langendorff model, hearts were exposed to 1 hour of hypothermic (10 degrees to 12 degrees C), global ischemia followed by 30 minutes of reperfusion. Isosmotic cardioplegia was administered as a single 50 ml bolus of either standard St. Thomas' Hospital solution ([K+]o x [Cl-]o = 2566.4 (mmol/L)2) or low Cl- St. Thomas' Hospital solution ([K+]o x [CI-]o = 700 (mmol/L)2). Chloride was replaced by a large, impermeant ion, methanesulfonate. Postreperfusion systolic function and atrioventricular conduction times were measured before ischemia and after reperfusion. RESULTS: Hearts receiving low Cl- St. Thomas' Hospital cardioplegia demonstrated significantly better postischemic functional recovery (74% +/- 3%) compared with those treated with standard high Cl- St. Thomas' Hospital solution (55% +/- 4%, p = 0.003). In addition, atrioventricular conduction times remained normal in the low Cl- group but were significantly prolonged in the St. Thomas' Hospital group. CONCLUSIONS: Lowering the KCl product of St. Thomas' Hospital solution makes it isotonic with plasma and prevents cellular edema. This ameliorates the detrimental functional and electrophysiologic sequelae of hypothermic, hyperkalemic cardioplegia.

Stoma creation through the stoma site: a rapid, safe technique.

UNLABELLED: Stoma creation often involves a separate laparotomy incision. Recently, laparoscopy was suggested to minimize the morbidity associated with conventional open stomal techniques. We describe and evaluate a technique of stoma creation done directly through the stoma site, avoiding both laparotomy and laparoscopy. METHODS: Charts of 36 patients who underwent attempted stoma creation using this closed technique were retrospectively reviewed. RESULTS: A total of 32 patients had stomas successfully created in this fashion (closed group); although four patients failed and required laparotomy (open group), there was an overall success rate of 89 percent. Blood loss (17 +/- 5 vs. 350 +/- 130 ml; P < .001), operative time (52 +/- 8 vs. 169 +/- 35 minutes; P < 0.001), and complications (3/32 vs. 4/4; P < 0.001) favored the closed group. No factors, including diagnosis, obesity, or previous abdominal surgery were identified that contraindicated use of the closed technique. CONCLUSIONS: Stomas can be safely made in a high proportion of patients without the need for laparotomy or laparoscopy. Failure of the closed technique identifies a group of patients who have a high associated operative time, blood loss, and morbidity when laparotomy is used for stoma creation and in whom laparoscopic procedures may improve results.