Christian Detter

Use of the voice-controlled and computer-assisted surgical system zeus for endoscopic coronary artery bypass grafting

OBJECTIVE With the aim of performing a completely endoscopic coronary bypass anastomosis, we have undertaken an experimental and clinical study using robotic instrumentation and voice-controlled camera guidance. METHODS The ZEUS Robotic Surgical System (Computer Motion Inc, Goleta, Calif) consists of three interactive robotic arms and a control unit, allowing the surgeon to move the instrument arms in a scaled down mode. The third arm (AESOP, Computer Motion) positions the endoscope via voice control. PHASE I In a phantom model, vascular grafts were anastomosed to the left anterior descending coronary artery (LAD) of 50 pig hearts with either 2- or 3-dimensional visualization. PHASE II In 6 dogs (FBI 20-25 kg) the left internal thoracic artery (LITA) was harvested endoscopically. Then the animals were placed on an endovascular cardiopulmonary bypass system (Port-Access, Heartport, Inc, Redwood City, Calif). Anastomosis of the LITA to the LAD was performed endoscopically with the telemetric ZEUS instruments. Flow rates through the LITA were measured by Doppler analysis. PHASE III Two patients were operated on with the ZEUS system. After endoscopic harvesting of the LITA and cardiopulmonary bypass with the Port-Access system, the bypass graft (LITA-LAD) was anastomosed endoscopically with the ZEUS system through three thoracic ports. RESULTS In the dry laboratory, the time range required for the robotically assisted coronary anastomosis was 35 to 60 minutes with 2-dimensional visualization and 16 to 32 minutes with 3-dimensional visualization. In the animal experiments, the median time for endoscopic harvesting of the LITA was 86 minutes (range 56-120 minutes) and for the anastomosis, 42 minutes (range 35-105 minutes); flow rates through the LITA ranged between 22 and 45 mL/min. In the clinical cases, preparation times for the LITA were 83 and 110 minutes, respectively, and anastomosis times, 42 and 40 minutes, respectively. Doppler flow rates measured 125 and 85 mL/min, respectively. Both patients had an uneventful follow-up angiogram and postoperative course. CONCLUSIONS With sophisticated robotic technology, a completely endoscopic anastomosis of the LITA to the LAD is possible, allowing technically precise operations within acceptable time limits.

Early experience with robotic technology for coronary artery surgery

BACKGROUND To achieve an endoscopic coronary bypass anastomoses we performed a study with endoscopic robotic instrumentation and camera guidance using three-dimensional (3-D) visualization. METHODS The surgical robotic system ZEUS (Computer Motion Inc, Goleta, CA) consists of three interactive robotic arms and a control unit allowing the surgeon to move the instrument arms in a scaled down mode. The third arm (AESOP, Computer Motion Inc, Goleta, CA) positions the endoscope via voice control. The study had three phases. Phase I: In a phantom model, end-to-side anastomoses between vein grafts and the left anterior descending coronary artery (LAD) of 109 pig hearts were performed. Phase II: In 6 dogs (FBI, 20-25 kg) the left internal mammary artery (LIMA) was harvested endoscopically. During Port-Access (Heartport Inc, Redwood City, CA) cardiopulmonary bypass (CPB), LIMA and LAD were then anastomosed endoscopically with the help of telemetric ZEUS instruments (Computer Motion Inc). Phase III: A total of seven patients were operated on with help of the ZEUS system (Computer Motion Inc). After endoscopic LIMA harvesting and CPB using the Port-Access (Heartport Inc) system, the bypass graft (LIMA to LAD) was anastomosed endoscopically through three thoracic ports in 2 patients. Another 3 patients were operated on off-pump with regional stabilization and 2 patients with sternotomy and routine CPB. RESULTS The practice with the phantom model and the subsequent animal experiments allowed the surgeons to gain sufficient experience for the clinical setting. In the clinical cases, times for anastomoses ranged from 20 to 42 minutes. Median internal mammary artery flow rate was 74 mL per minute (range 36-110 mL per minute). One patient in the off-pump group was converted to CPB and routine anastomosis. All patients had an uneventful angiographic control and postoperative course. CONCLUSIONS Using telemetic technology, a completely endoscopic anastomosis of LIMA to LAD is possible on the arrested heart, as well as on the beating heart.

Three-dimensional video and robot-assisted port-access mitral valve operation

BACKGROUND In order to minimize surgical trauma, video-assisted mitral valve operation has been started using the Port-Access technique with the addition of a three-dimensional visualization system (Vista Cardiothoracic Systems Inc, Westborough, MA) and a voice-controlled camera-holding robotic arm (Aesop; Computer Motion Inc, Goleta, CA). METHODS Port-Access mitral valve replacement or repair (PAMVR) was undertaken using an endovascular cardiopulmonary bypass (CPB) system. Fifty patients underwent Port-Access mitral valve replacement or repair. A three-dimensional thoracoscope was inserted allowing complete three-dimensional projection of the mitral valve (Vista). In the last 20 patients, the camera was attached to a robotic arm (Aesop), which allowed stabilization and voice-activated movement of the camera. Mitral valve repair was performed in 26 patients, and the valve was replaced in 24 patients with a mechanical valve prosthesis. RESULTS Median time of operation was 4.2 hours, aortic cross-clamp time 83 minutes, CPB time 125 minutes, intensive care unit stay 1.5 days and hospitalization 9.0 days. Three months follow-up was complete in 40 patients, with 34 patients (85%) in New York Heart Association class I and 6 patients in class II. Mortality was 0% and rate of reoperation was 2%, with a follow-up time up to 1.5 years postoperatively. CONCLUSIONS Using three-dimensional video and robotic assistance, it was possible to minimize the length of skin incision, but at the same time to optimally visualize the whole mitral valve apparatus in order to perform true Port-Access mitral valve operation, including various repair techniques.

Fluorescent Cardiac Imaging A Novel Intraoperative Method for Quantitative Assessment of Myocardial Perfusion During Graded Coronary Artery Stenosis

Background— The purpose of the present study was to examine whether the effect of coronary stenoses of variable severity on myocardial perfusion can be quantitatively assessed in vivo by analysis of fluorescent cardiac imaging (FCI) compared with the gold standard, the fluorescent microsphere method. FCI is a novel technology to visualize coronary vessels and myocardial perfusion intraoperatively using the indocyanine green dye with an infrared-sensitive imaging device. Methods and Results— Graded stenoses and total vessel occlusion of the left anterior descending coronary artery were created in 11 open-chest pigs. Stenoses were graded to reduce resting left anterior descending coronary artery flow by 25%, 50%, 75%, and 100% of baseline flow measured by transit-time flowmeter. FCI images were analyzed with a digital image processing system. The impairment of myocardial perfusion was quantified by background-subtracted peak fluorescence intensity and slope of fluorescence intensity obtained with FCI and compared with myocardial blood flow assessed by fluorescent microsphere. All stenoses resulted in an impairment of myocardial perfusion visualized by FCI. Occlusion of the left anterior descending coronary artery resulted in a total perfusion defect (no fluorescence intensity) of the corresponding anterior myocardial wall. During graded stenosis and total vessel occlusion, normalized background-subtracted peak fluorescence intensity and slope of fluorescence intensity decreased significantly (P<0.0001). Both background-subtracted peak fluorescence intensity (r=0.92, P<0.0001) and slope of fluorescence intensity (r=0.93, P<0.0001) analyzed by FCI demonstrated good linear correlation with fluorescent microsphere–derived myocardial blood flow. Conclusions— The impairment of myocardial perfusion in response to increased coronary stenosis severity and total vessel occlusion can be quantitatively assessed by FCI and correlates well with results obtained by fluorescent microsphere.

The Spectrum of Syndromes and Manifestations in Individuals Screened for Suspected Marfan Syndrome

The diagnosis of Marfan syndrome (MFS) is based on evaluating a large number of clinical criteria. We have observed that many persons presenting in specialized centers for “Marfan‐like” features do not have MFS, but exhibit a large spectrum of other syndromes. The spectrum of these syndromes and the distribution of “Marfan‐like” features remain to be characterized. Thus, we prospectively evaluated 279 consecutive patients with suspected MFS (144 men and 135 women at a mean age of 34 ± 13 years) for presence of 27 clinical criteria considered characteristic of MFS. The most frequent reasons to refer individuals for suspected MFS were skeletal features (31%), a family history of MFS, or aortic complications (29%), aortic dissection or aneurysm (19%), and eye manifestations (9%). Using established criteria, we confirmed MFS in 138 individuals (group 1) and diagnosed other connective tissue diseases, both with vascular involvement in 30 (group 2) and without vascular involvement in 39 (group 3), and excluded any distinct disease in 72 individuals (group 4). Clinical manifestations of MFS were present in all four patient groups and there was no single clinical criterion that exhibited positive and negative likelihood ratios that were per se sufficient to confirm or rule out MFS. We conclude that “Marfan‐like” features are not exclusively indicative of MFS but also of numerous, alternative inherited diseases with many of them carrying a hitherto poorly defined cardiovascular risk. These alternative diseases require future study to characterize their responses to therapy and long‐term prognosis.

Immunologic reaction and viability of cryopreserved homografts

Homograft cell viability after cryopreservation was investigated and cytoimmunologic monitoring was performed during the early postoperative course to research possible immunologic reactions after allograft aortic valve replacement. After cryopreservation, morphologic observations were made, a nonradioactive cell proliferation assay was used, and prostaglandin I2 secretion of the remaining endothelial cells was determined. Cytoimmunologic monitoring was performed daily within the first 3 weeks postoperatively. An increase of the activation index greater than 1 was rated as an immunologic reaction. Maintained metabolic activity of graft endothelial cells after cryopreservation was confirmed by prostaglandin I2 release (9.24 +/- 3.48 ng/cm2 basic release and 20.1 +/- 5.76 ng/cm2 when stimulated with 25 mumol/L Na arachidonic acid). Cell proliferation was indicated after graft incubation with the nonradioactive viability kit (0.27 +/- 0.9 at 450 nm). Cytoimmunologic examinations (n = 861) after homograft implantation showed a more intense activation in patients with ABO-incompatible grafts (activation index 2.1 +/- 1.6, n = 16) than in those with ABO-compatible grafts (activation index 1.3 +/- 0.8, n = 17). In these groups, the duration of activation by cytoimmunologic monitoring was 2.8 +/- 1.5 days and 1.3 +/- 0.6 days, respectively (p < 0.041). No activation was observed in 8 patients after xenograft valve replacement (p < 0.01). Our data indicate that cryopreservation of homograft valves represents a cell- and tissue-protective preservation method. Postoperatively, all homograft valves caused immunologic reactions, which were reversible without immunosuppression treatment.

Myeloperoxidase deficiency preserves vasomotor function in humans

Aims Observational studies have suggested a mechanistic link between the leucocyte-derived enzyme myeloperoxidase (MPO) and vasomotor function. Here, we tested whether MPO is systemically affecting vascular tone in humans. Methods and results A total of 12 135 patients were screened for leucocyte peroxidase activity. We identified 15 individuals with low MPO expression and activity (MPOlow), who were matched with 30 participants exhibiting normal MPO protein content and activity (control). Nicotine-dependent activation of leucocytes caused attenuation of endothelial nitric oxide (NO) bioavailability in the control group (P < 0.01), but not in MPOlow individuals (P = 0.12); here the MPO burden of leucocytes correlated with the degree of vasomotor dysfunction (P = 0.008). To directly test the vasoactive properties of free circulating MPO, the enzyme was injected into the left atrium of anaesthetized, open-chest pigs. Myeloperoxidase plasma levels peaked within minutes and rapidly declined thereafter, reflecting vascular binding of MPO. Blood flow in the left anterior descending artery and the internal mammary artery (IMA) as well as myocardial perfusion decreased following MPO injection when compared with albumin-treated animals (P < 0.001). Isolated IMA-rings from animals subjected to MPO revealed markedly diminished relaxation in response to acetylcholine (P < 0.01) and nitroglycerine as opposed to controls (P < 0.001). Conclusion Myeloperoxidase elicits profound effects on vascular tone of conductance and resistance vessels in vivo. These findings not only call for revisiting the biological functions of leucocytes as systemic and mobile effectors of vascular tone, but also identify MPO as a critical systemic regulator of vasomotion in humans and thus a potential therapeutic target.

ROBOTICALLY ASSISTED ENDOSCOPIC CORONARY ARTERY BYPASS PROCEDURES WITHOUT CARDIOPULMONARY BYPASS

Minimally invasive coronary artery surgical procedures still require a minithoracotomy or partial sternotomy for the coronary artery anastomosis. The clinical performance of manual endoscopic coronary artery grafting is extremely difficult and has not been published yet. For this reason, computer-assisted systems have been developed to facilitate endoscopic microsurgery. 1 This is the description of the first clinical use of the voice-controlled and computer-assisted system ZEUS (Computer Motion Inc, Goleta, Calif) for endoscopic coronary artery surgical procedures on the beating heart without cardiopulmonary bypass. Four patients (3 men and 1 woman, aged 44 to 64 years) with an isolated proximal stenosis of the left anterior descending (LAD) coronary artery were evaluated for the procedure. After approval by the local ethics committee, written informed consent was given by the patients. At surgery, 3 thoracoscopic ports (10 mm and 5 mm) were inserted in the left side of the chest. First, the left internal thoracic artery (LITA) was dissected endoscopically. After this, a small parasternal incision (4 cm) was made above the 5th intercostal space. The pericardium was incised through the minithoracotomy. The LAD was visualized and the Octopus system (Medtronic GmbH, Dusseldorf, Germany) was used for coronary artery stabilization. One stabilization pod was inserted through the incision and the second one through one of the thoracoscopic ports. The ZEUS Robotic Surgical System was used to perform an endoscopic graft anastomosis. This system consists of 3 interactive robotic arms placed at the operating table, a computer controller, and an ergonomically enhanced surgeon console. One robotic arm was used to position the endoscope by means of voice control, and the other 2 robotic arms manipulated the surgical instruments under the surgeon’s direct control. A 3-dimensional camera (Vista Cardiothoracic Systems Inc, Westborough, Mass) was inserted through the minithoracotomy. The 2 instrument controllers were inserted through 2 of the thoracoscopic ports

Analysis of phenotype and genotype information for the diagnosis of Marfan syndrome.

Sheikhzadeh S, Kade C, Keyser B, Stuhrmann M, Arslan‐Kirchner M, Rybczynski M, Bernhardt AM, Habermann CR, Hillebrand M, Mir T, Robinson PN, Berger J, Detter C, Blankenberg S, Schmidtke J, von Kodolitsch Y. Analysis of phenotype and genotype information for the diagnosis of Marfan syndrome.

Long-term prognosis of surgically-treated aortic aneurysms and dissections in patients with and without Marfan syndrome

OBJECTIVE Aortic aneurysms and dissections are the leading causes of premature death in Marfan syndrome (MfS). This study aims to compare long-term results of surgically treated aortic aneurysms and dissections in patients with and without MfS in respect to early and late prognosis. METHODS From March 1975 to August 1994, 33 patients with classic MfS (group A, age 34.2 +/- 9 years) and 298 patients with non-fibrillinopathic aortic disease (group B, age 54 +/- 13 years) underwent aortic surgery. Acute dissections occurred in 57.6 (A) versus 37.9% (B). A total of 54.6% of patients in group A were treated with a composite graft versus 16.4% in B. The aortic arch and the descending aorta was replaced in 30.4% of MfS patients and 24.9% of patients without MfS. RESULTS We observed 7 (25.0%, A) versus 35 (14.2%, B) late deaths among the 28 (A) versus 247 (B) early survivors. In 5 patients (17.9%) of A and 8 patients (3.2%) of B, late death was caused by redissection or recurrent aneurysm (P < 0.001). Long-term survival after 5, 10 and 15 years in group A was 82 +/- 7, 60 +/- 11 and 30 +/- 22%, and 75 +/- 3, 69 +/- 3 and 64 +/- 4% in group B. A total of 22 reoperations were performed in 11 MfS patients, 17 reoperations were due to recurrent aortic diseases. Three of the 8 patients underwent reoperation after Wheat procedure because of sinus valsalva aneurysm. None of the patients with composite graft replacement needed reoperation in this segment, but 3 patients suffered from redissection at the proximal aortic arch. In group B, reoperations were significantly less frequent (10.7%) compared to MfS patients (66.7%; P < 0.001). CONCLUSIONS Surgical treatment of aortic disease in MfS patients is associated with a high risk of redissection and recurrent aneurysm. If the ascending aorta needs to be replaced, we recommend the composite graft technique and a more aggressive approach to reduce the frequency of distal reoperations. In order to reduce the high reoperation rate in MfS patients, frequent clinical follow-up may contribute to improve life expectancy in MfS patients.