Stephan Jacobs

Randomized Comparison of Minimally Invasive Direct Coronary Artery Bypass Surgery Versus Sirolimus-Eluting Stenting in Isolated Proximal Left Anterior Descending Coronary Artery Stenosis

OBJECTIVESnThe purpose of this randomized study was to compare sirolimus-eluting stenting (SES) with minimally invasive direct coronary artery bypass (MIDCAB) surgery for patients with isolated proximal left anterior descending (LAD) coronary artery disease.nnnBACKGROUNDnBare-metal stenting is inferior to MIDCAB surgery in patients with isolated proximal LAD lesions due to a higher reintervention rate with similar results for mortality and reinfarction. SES are effective in restenosis reduction.nnnMETHODSnA total of 130 patients with significant proximal LAD coronary artery disease were randomized to either SES (n = 65) or MIDCAB surgery (n = 65). The primary clinical end point was noninferiority in freedom from major adverse cardiac events (MACE), such as cardiac death, myocardial infarction, and the need for target vessel revascularization within 12 months.nnnRESULTSnFollow-up was completed for all patients. MACE occurred in 7.7% of patients after stenting, as compared with 7.7% after surgery (p = 0.03 for noninferiority). The individual components of the combined end point revealed mixed results. Although noninferiority was revealed for the difference in death and myocardial infarction (1.5% vs. 7.7%, noninferiority p < 0.001), noninferiority was not established for the difference in target vessel revascularization (6.2% vs. 0%, noninferiority p = 0.21). Clinical symptoms improved significantly in both treatment groups in comparison with baseline, and the percentage of patients free from angina after 12 months was 81% versus 74% (p = 0.49).nnnCONCLUSIONSnIn isolated proximal LAD disease, SES is noninferior to MIDCAB surgery at 12-month follow-up with respect to MACE at a similar relief in clinical symptoms.

Comparison of Bare-Metal Stenting With Minimally Invasive Bypass Surgery for Stenosis of the Left Anterior Descending Coronary Artery A 5-Year Follow-Up

Background— Randomized trials comparing stenting with minimally invasive direct coronary artery bypass surgery in patients with isolated proximal left anterior descending lesions have shown a significantly higher reintervention rate for stenting and similar results for mortality and reinfarction at short-term follow-up. Long-term follow-up data are sparse. Methods and Results— Patients with isolated proximal left anterior descending stenosis were randomized to either surgery (n=110) or bare-metal stenting (n=110). At 5 years, follow-up data were obtained with respect to the primary end point of death, reinfarction, or repeated target vessel revascularization. Clinical symptoms were assessed by the Canadian Cardiovascular Society (CCS) classification. Follow-up information was completed for 216 patients (98.2%), and mean follow-up was 5.6±1.2 years. With respect to mortality (surgery, 12%; stenting, 10%; P=0.54) and reinfarctions (surgery, 7%; stenting, 5%; P=0.46), there were no differences between treatment strategies. The need for repeated target vessel revascularization was significantly higher after stenting (32%) compared with surgery (10%; P<0.001). Clinical symptoms improved significantly in both treatment groups compared with baseline; however, there was a favorable trend for surgery (stenting: CCS, 2.6±0.9 to 0.5±0.8, P<0.001; surgery: CCS, 2.6±0.9 to 0.3±0.6, P<0.001; P=0.05, stenting versus surgery). Conclusions— At the 5-year follow-up, minimally invasive bypass surgery and bare-metal stenting showed similar results for the end points of mortality and reinfarctions. However, the reintervention rate is higher after stenting, and the relief in clinical symptoms is slightly better after surgery.

Limitations for manual and telemanipulator-assisted motion tracking—implications for endoscopic beating-heart surgery

BACKGROUNDnSurgical performance is limited by human factors. Beating-heart surgery requires full dexterity and motion tracking. Currently techniques for total endoscopic beating-heart bypass grafting using telemanipulation systems are being developed. The aim of this study was to assess the limitations for manual and telemanipulator-assisted motion tracking using the da Vinci telemanipulator system.nnnMETHODSnTo simulate beating-heart conditions an endoscopic trainer was developed. Twenty subjects were asked to touch targets manually and with telemanipulator assistance with different patterns of increasing index of difficulty (resting model, unstabilized, and stabilized model with a frequency of 35, 60, and 90 beats per minute). In addition one task was performed using different scaling ratios on a resting model. The times between hits as well as errors were electronically recorded.nnnRESULTSnThere was no significant impact of various frequencies and amplitudes for manual tracking. The average values for the delay (k(m)[ms]) and information-processing (c(m) [ms/bit]) constants for the manual tasks were 201 ms and 86 ms/bit respectively. Both the delay constant (k(t) = 630 ms; p < 0.0005) and the information-processing constant (c(t) = 250 ms/bit; p < 0.0005) were increased for the telemanipulator-assisted tasks at rest. When working on moving targets telemanipulator-assisted tracking required significantly more time and led to more errors. At a frequency of 90 beats per minute telemanipulator-assisted tracking became more difficult.nnnCONCLUSIONSnEndoscopic beating-heart bypass grafting requires optimal stabilization to avoid inaccuracies due to incomplete motion tracking. At higher frequencies telemanipulator-assisted tracking became more difficult, demonstrating the technical limits of current telemanipulator technology.

Facilitated endoscopic beating heart coronary artery bypass grafting using a magnetic coupling device.

BACKGROUNDnSuturing of a coronary anastomosis in totally endoscopic coronary artery bypass grafting on the beating heart is technically demanding. The potential benefits of the endoscopic Magnetic Vascular Positioner device (Ventrica, Inc, Fremont, Calif) to facilitate construction of a coronary anastomosis in a closed chest environment were evaluated.nnnMETHODSnTotally endoscopic coronary artery bypass grafting on the beating heart was performed in 8 foxhound-beagle inbred dogs with the da Vinci telemanipulation system (Intuitive Surgical, Mountain View, Calif). A prototype of the endoscopic Magnetic Vascular Positioner device was used to facilitate construction of the coronary anastomosis. One pair of magnets was inserted in the internal thoracic artery and left anterior descending artery using robotic instruments to guide and place the endoscopic delivery platform. All animals underwent angiography; gross inspection of the anastomotic site was performed after excision of the hearts.nnnRESULTSnThe procedure was accomplished in all animals in 169 minutes (155-190 minutes). Dissection of the left anterior descending coronary artery (6.5 minutes; 1-20 minutes), positioning of the stabilizer (8.5 minutes; 7-16 minutes), placement of occlusion tapes (6 minutes, 3-10 minutes), and arteriotomy 5.5 minutes (3-30 minutes) was achieved without problems. By use of the Magnetic Vascular Positioner device, the anastomosis at the graft site was performed with the graft still in situ. Except for 1 premature deployment, all other deployments were easily accomplished in 3 minutes (1-28 minutes). The following adverse events were encountered: bleeding from the right ventricle caused by occlusion tape (1), anastomotic leakage on reperfusion requiring repair stitches (2), and anastomotic occlusion as a result of thrombus (1). All except 1 animal with a patent graft and anastomosis survived the procedure. The overall patency was 7 of 8.nnnDISCUSSIONnThe combination of robotic technology allowing for dexterous manipulation in a closed chest environment and a simple yet effective and timesaving technique for anastomotic coupling may facilitate beating heart totally endoscopic coronary artery bypass grafting.

Robotic coronary artery bypass grafting (CABG): The Leipzig experience

Technical and anatomical limitations as well as human factors complicate endoscopic coronary bypass surgery. Computer-enhanced telemanipulation systems overcome some of these shortcomings by restoring the dexterity and precision of a distant operator (surgeon) within a confined space. Endoscopic coronary artery bypass grafting (CABG) has evolved from a merely experimental approach to a clinical concept. Although CABG was initially exclusively performed on the arrested heart, adjunct technologies such as endoscopic vacuum-assisted stabilizers now allow a closed-chest, beating-heart procedure. The development of anastomotic devices, and further refinements in telemanipulator technology, optical systems, and image-guided augmented-reality scenarios will greatly facilitate endoscopic bypass grafting in the future.

Computer-enhanced endoscopic coronary artery bypass grafting: the da Vinci experience

Anatomical and technical limitations as well as human factors render endoscopic coronary artery bypass surgery difficult. The da Vinci telemanipulator overcomes some of these shortcomings by restoring the dexterity and precision of a distant operator within the confined space in a closed-chest environment. Using the da Vinci system, total endoscopic coronary artery bypass grafting has evolved from a merely experimental surgical approach to a clinically applicable treatment option. Initially exclusively performed on the arrested heart, adjunct technologies such as endoscopic vacuum-assisted stabilizers now allow a single-vessel closed-chest beating heart procedure in selected patients. Despite the technical progress, endoscopic multivessel bypass grafting has yet to be achieved. The development of endoscopically applicable anastomotic devices and heart-positioning devices along with further refinements in telemanipulator technology, better optical systems, and image guided augmented reality scenarios may facilitate endoscopic bypass grafting in the future.

Value of augmented reality-enhanced transesophageal echocardiography (TEE) for determining optimal annuloplasty ring size during mitral valve repair.

BACKGROUNDnMitral valve (MV) annuloplasty is an integral part of MV repair, but sizing under direct vision is occasionally challenging. Furthermore, traditional sizing is not possible for percutaneous MV repair techniques. This study compared augmented reality-enhanced three-dimensional (3D) transesophageal echocardiography (TEE) for determining MV annuloplasty size with conventional surgical sizing.nnnMETHODSnIn patients undergoing elective MV repair, a 3D MV reconstruction was performed using TEE. Modified 4D valve assessment software was used to create 3D computer-aided design models of standard annuloplasty rings (28 to 36 mm), which were stored in a digital database. These virtual 3D annuloplasty ring templates were superimposed on the preoperative 3D TEE reconstructions of the MV, and results were compared with conventional sizing under direct vision. A post hoc validation of the 3D models was performed using the implanted rings as a control. The echocardiographer was blinded to the implanted ring size.nnnRESULTSnThe study included 50 patients. The correlation between the selected 3D annuloplasty ring template and the implanted annuloplasty ring size was 0.83. Thirty ring templates (60%) were the same size as the implanted annuloplasty ring, 19 templates (38%) differed by +/-2 mm in size, and 1 template differed by +4 mm. Postoperatively, the validation protocol revealed a correlation of 0.94 between the size of the ring templates and the implanted annuloplasty prostheses.nnnCONCLUSIONSnAugmented reality-enhanced TEE for determining optimal annuloplasty ring size during MV repair correlates well with conventional surgical sizing and may facilitate future percutaneous MV repair techniques.

Facilitated MIDCAB using a magnetic coupling device

A 59-year-old male with chronic occlusion of the left anterior descending coronary artery underwent a minimally invasive direct coronary artery bypass procedure using the second generation of a magnetic anastomotic coupling device. Postoperative angiogram demonstrated excellent patency and flow.

Limitations for manual and telemanipulator-assisted motion tracking and dexterity for endoscopic surgery

Background: Surgical precision is limited by human factors. Surgery on a moving object requires full dexterity and motion tracking. Currently, techniques for total endoscopic surgery using telemanipulation systems are being developed. Aim of this study was to assess the limitations for manual and telemanipulator-assisted motion tracking using the da Vinci™ telemanipulator system. Methods: To simulate moving object conditions, an endoscopic trainer was developed. Twenty subjects were asked to touch targets manually and with telemanipulator assistance with different patterns of increasing index of difficulty (resting model, unstabilized and stabilized model with a frequency of 35, 60 and 90/bpm). In addition, one task was performed using different scaling ratios on a resting model. The times between hits as well as misses were electronically recorded. Results: There was no significant impact of various frequencies and amplitudes for manual tracking. The average values for the delay (km [ms]) and information-processing (cm [ms/bit]) constants for the manual tasks were 201 and 86 ms/bit, respectively. As compared to manual control, the delay constant for the telemanipulator-assisted tasks of resting targets was three times longer (kt=630 ms; p<0.0005) and the information-processing constant was less (ct=250 ms/bit; p<0.0005). When working on moving targets, telemanipulator-assisted control and tracking required significantly more time and led to more errors. At a frequency of 90 bpm, telemanipulator-assisted control and tracking became almost impossible. Conclusion: Endoscopic beating heart bypass grafting requires an optimal stabilization to avoid inaccuracies due to incomplete motion control and tracking. At higher speeds (equaling a frequency of 90 bpm), control and tracking became almost impossible, demonstrating the technical limits of current telemanipulator technology.

Closed-chest, robotically assisted CABG

Total endoscopic coronary artery bypass grafting is a robotic assisted procedure to graft the left internal thoracic artery to the left anterior descending coronary artery without opening the chest. Through four 1-cm port incisions the procedure can be performed on the beating heart using a telemanipulation system and an endoscopic vacuum stabilizer to locally immobilize the heart.