Jürg Grünenfelder

Influence of three-dimensional vision on surgical telemanipulator performance

Background: Different viewing conditions (two- and three-dimensional National Television Standard Committee [2D-NTSC and 3D-NTSC] and two-dimensional high-definition television [2D-HDTV]) on telemanipulator performance were evaluated. Methods: Six taskes were performed by 15 endoscopic surgeons using the daVinci telemanipulation system. Performance time and errors were measured. Encoder data from the system were used for kinematic analysis of motion. A self-evaluation questionnaire regarding performance under various viewing conditions was obtained. Results: Resolution was better with 2D-HDTV. The estimate of relative distance was not influenced by the different visualization systems. Motor skill tasks were performed faster with binocular vision (3D-NTSC) than with monocular vision (2D-NTSC, 2D-HDTV). For both 2D settings, the deceleration phase of motion was prolonged (p < 0.05 vs 3D). Peak velocity was reduced with 2D-HDTV as compared with 3D-NTSC (p = 0.01). The surgeons tended to favor the 3D system despite their use of 2D systems in their own practice. Conclusions: Three-dimensional vision enhances telemanipulator performance as compared with a 2D system at the same or higher level of resolution. Because it allows faster and more precise movement, future surgical systems should focus on 3D visualization.

Endoscopic computer-enhanced beating heart coronary artery bypass grafting

BACKGROUNDnTelemanipulation systems have enabled coronary revascularization on the arrested heart. The purpose of this study was to develop a technique for computer-enhanced endoscopic coronary artery bypass grafting on the beating heart.nnnMETHODSnThe operation was performed using the daVinci telemanipulation system. Through three ports, the left internal thoracic artery was harvested in 10 mongrel dogs (30 to 35 kg) using single right-lung ventilation and CO2 insufflation. Through a fourth port an articulating stabilizer, manipulated from a second surgical console, was inserted to stabilize the heart. The left anterior descending artery was snared using silicone elastomer slings anchored in the stabilizer cleats and the graft to coronary artery anastomosis was performed.nnnRESULTSnIn 7 of 10 dogs, total endoscopic beating heart bypass grafting, cardiac stabilization, arteriotomy, and arterial anastomosis were performed using computer-enhanced technology. Endoscopic stabilization and temporary left anterior descending artery occlusion were well tolerated. All grafts were patent although minor strictures were found in 2. In 3 dogs, the procedure could not be completed (1 ventricular arrhythmia, 1 left atrial laceration, and 1 right ventricular outflow tract compression).nnnCONCLUSIONSnEndoscopic beating heart coronary artery bypass grafting is possible in a canine model using a computer-enhanced instrumentation system and articulating stabilization.

Up-regulation of Bcl-2 through hyperbaric pressure transfection of TGF-β1 ameliorates ischemia-reperfusion injury in rat cardiac allografts

BACKGROUNDnOxidative stress after ischemia-reperfusion of cardiac allografts leads to activation of cardiomyocytes and production of cytokines. Bcl-2, an inhibitor of the apoptotic pathway, also has strong antioxidant properties. Ischemia-reperfusion injury after transplantation leads to decreased bcl-2 and increased tumor necrosis factor (TNF)-alpha levels. Transforming growth factor (TGF)-beta1 is known to attenuate ischemia-reperfusion injury and inhibits apoptosis of myofibroblasts. We hypothesize that TGF-beta1, prevents bcl-2 cleavage and increased TNF-alpha production.nnnMETHODSnRat PVG donor hearts were heterotopically transplanted into ACI recipients. Donor hearts were procured and assigned to groups: (1) intracoronary TGF-beta1 (200 ng/ml) perfusion and pressure at 78 psi for 45 minutes (n = 4); (2) intracoronary TGF-beta1 perfusion and incubation for 45 minutes without pressure (n = 4), (3) saline perfusion and incubation for 45 minutes without pressure (n = 4). Hearts were procured 4 hours after transplantation and analyzed by reverse transcriptase-polymerase chain reaction for bcl-2 mRNA expression, ELISA for TNF-alpha, and for myeloperoxidase activity (MPO).nnnRESULTSnBcl-2 decreased in untreated animals (bcl-2:G3PDH ratio = 0.85 +/- 0.73 vs 1.16 +/- 0.11, not significant [NS]), whereas TNF-alpha increased to 669.99 +/- 127.09 vs 276.84 +/- 73.65 pg/mg total protein in controls (p < 0.003). In TGF-beta(1) pressure-treated hearts, bcl-2 was up-regulated (2.49 +/- 0.6 vs 1.16 +/- 0.11, controls, p < 0.005), whereas TNF-alpha was unchanged (396.1 +/- 100.38 vs 276.84 +/- 73.65 pg/mg, NS). Hearts treated with TGF-beta1 and pressure showed significant up-regulation of bcl-2 compared with hearts treated with TGF-beta1 without pressure (2.49 +/- 0.6 vs 1.17 +/- 0.6, p < 0.02). MPO showed no differences.nnnCONCLUSIONSnBcl-2 is down-regulated and TNF-alpha up-regulated in this model of ischemia-reperfusion injury. Furthermore, TGF-beta1 is linked to this process and ameliorates reperfusion injury by up-regulating bcl-2 and inhibiting TNF-alpha. Therapeutic overexpression of myocardial TGF-beta1 may be clinically useful to control ischemia-reperfusion injury associated with cardiac transplantation.

Der moderne Aortenklappenersatz: minimalinvasiv oder «TAVI»

Der aktuelle Trend beim Aortenklappenersatz geht in Richtung geringerer Invasivitat, des sogenannten minimalinvasiven Aortenklappenersatzes.

Vorhofflimmern und Herzchirurgie: eine starke Verbindung?

Das Vorhofflimmern (VHF) ist mit einer Pravalenz von 1% in der Gesamtbevolkerung die haufigste Herzrhythmusstorung. Wo fruher geschnitten und genaht wurde, wird heute die Ablation mittels neuer Energiequellen durchgefuhrt. Der aktuelle Wissensstand ermoglicht eine individuelle Therapie fur jeden Patienten: Bei paroxysmalem VHF reicht oftmals die Isolation der Pulmonalvenen, bei nicht paroxysmalem VHF mussen jedoch zusatzliche Lasionen appliziert werden.

Fibrillation auriculaire et chirurgie cardiaque: que pouvons-nous offrir?

Avec une prevalence de 1% dans la population totale, la fibrillation auriculaire constitue l’arythmie cardiaque la plus frequente. Autrefois realisee par incision et suture, l’ablation est aujourd’hui pratiquee en utilisant de nouvelles sources d’energie. L’etat actuel des connaissances permet un traitement individuel de chaque patient; en cas de FA paroxystique, l’isolation des veines pulmonaires est souvent suffisante, alors qu’en cas de FA non paroxystique, des lesions supplementaires sont inevitables.