Showing papers by "Volkmar Falk published in 2005"

Motion estimation in beating heart surgery

Abstract: Minimally invasive beating-heart surgery offers substantial benefits for the patient, compared to conventional open surgery. Nevertheless, the motion of the heart poses increased requirements to the surgeon. To support the surgeon, algorithms for an advanced robotic surgery system are proposed, which offer motion compensation of the beating heart. This implies the measurement of heart motion, which can be achieved by tracking natural landmarks. In most cases, the investigated affine tracking scheme can be reduced to an efficient block matching algorithm allowing for realtime tracking of multiple landmarks. Fourier analysis of the motion parameters shows two dominant peaks, which correspond to the heart and respiration rates of the patient. The robustness in case of disturbance or occlusion can be improved by specially developed prediction schemes. Local prediction is well suited for the detection of single tracking outliers. A global prediction scheme takes several landmarks into account simultaneously and is able to bridge longer disturbances. As the heart motion is strongly correlated with the patient's electrocardiogram and respiration pressure signal, this information is included in a novel robust multisensor prediction scheme. Prediction results are compared to those of an artificial neural network and of a linear prediction approach, which shows the superior performance of the proposed algorithms.

Endoscopic Vascular Harvest in Coronary Artery Bypass Grafting Surgery: A Consensus Statement of the International Society of Minimally Invasive Cardiothoracic Surgery (ISMICS) 2005.

Abstract: ObjectiveThis purpose of this consensus statement was to compare endoscopic vascular graft harvesting (EVH) with conventional open vascular harvesting (OVH) in adults undergoing coronary artery byp...

Surgical experience with 77 primary cardiac tumors.

Abstract: Background To assess the prognosis and to develop management strategies for primary cardiac tumors all patients were included in an ongoing study. Method From Oct. 1994 until December 2003 we prospectively evaluated all patients with cardiac tumors. Follow up examinations were performed every 12 months. Results There were a total of 77 primary cardiac tumors. Seventy-three were benign: myxoma (n=59), papillary fibroelastoma (n=11), lipoma (n=2), fibroma (n=1) and four malignant sarcoma (n=4). The myxoma group consisted of 19 males and 40 females aged 12 to 88 years. Myxomas were located in the: left atrium in 50 (85%), left ventricle in 3 (5%), right atrium in 4 (7%) and on the mitral valve in 2 patients (3%). Papillary fibroelastoma was located on the aortic valve (n=4), mitral valve (n=3), right ventricle (n=2), left ventricle (n=1) and tricuspid valve (n=1). Both lipoma and the only fibroma were located in the right atrium. There were 4 primary cardiac sarcomas, located in the right ventricle (n=2), the pulmonary valve (n=1) and left atrium (n=1). Minimal invasive right thoracotomy was utilized in 19 of 73 patients all with benign tumor. There were two early deaths (3%): a myxoma patient with triple vessel disease and a LVEF less than 30% and one sarcoma patient. No recurrence or late death was observed in the group of benign tumors. However, two remaining patients with sarcoma had recurrent disease 10 and 15 month later, respectively. All patients were followed up with a total follow up of 203 patient years. Conclusion Surgical excision of benign cardiac tumors is a safe and curative treatment, which is feasible using minimally invasive right thoracotomy approach and provides excellent results. However, therapy of malignant cardiac tumors continues to have a poor prognosis despite individualization of approach.

Comparison of bare-metal stenting with minimally invasive bypass surgery for stenosis of the left anterior descending coronary artery: a 5-year follow-up.

Abstract: 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 P P 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.

Endoscopic vascular harvest in coronary artery bypass grafting surgery: a meta-analysis of randomized trials and controlled trials.

Abstract: ObjectiveThis meta-analysis sought to determine whether endoscopic vascular graft harvesting (EVH) improves clinical and resource outcomes compared with conventional open graft harvesting (OVH) in ...

Mechatronik in der HNO-Chirurgie Erste : Erfahrungen mit dem daVinci-Telemanipulator-System

Abstract: An einem kommerziell erhaltlichen Telemanipulator (daVinci, Intuitive Surgical, USA) wurden am Beispiel des endonasalen Zuganges zu den Nasennebenhohlen die potenziellen Vor- und Nachteile computergesteuerter Instrumente untersucht. Es wurden funf unterschiedliche Operationen an den Nasennebenhohlen an 14 anatomischen Praparaten durchgefuhrt und mit der konventionellen Op.-Technik verglichen. 140 Eingriffe an den Nasennebenhohlen wurden unter folgenden Kriterien untersucht: Freiheitsgrade, Zeitaufwand, Lerneffekt, Kraftruckfuhrung, Ergonomie. Die Instrumente des Telemanipulators verfugen in der „region of interest“ uber mehr Freiheitsgrade als konventionelle Instrumente. Der durchschnittliche zusatzliche Mehraufwand fur die Rustzeit des Systems lag in unserer Untersuchung bei 9±2 min. Die rhinochirurgisch erfahrenen Chirurgen schatzten den Wegfall der Kraftruckfuhrung als negativ ein und die Bewegungsskalierung als hilfreich. Sie bewerteten die ergonomische Gesamtsituation als besser im Vergleich zur konventionellen Methode. Der Telemanipulator bietet Vorteile bei der Anzahl der verfugbaren Instrumentenfreiheitsgrade, in der Moglichkeit der Instrumenteninteraktion („motion scaling“, „indexing“) und in der Ergonomie.

Diabetes in patients undergoing coronary artery bypass grafting. Impact on perioperative outcome.

Abstract: Diabetes mellitus is an established risk factor related to significant morbidity and mortality after coronary artery bypass grafting Data on 9682 patients undergoing coronary artery bypass grafting either with (n=8917) or without cardiopulmonary bypass (off-pump coronary artery bypass grafting; n=765) were subjected to an univariate analysis to identify potential associations between diabetes mellitus and 26 a priori selected perioperative outcome variables Those having a significant association with diabetes were then subjected to a stepwise logistic regression model to identify the impact of diabetes as compared to additional 22 different a priori chosen patient related risk factors and treatment variables Prevalence of outcome variables independently associated with diabetes has been determined in the subgroup of diabetics undergoing coronary artery bypass grafting with cardiopulmonary bypass or off-pump coronary artery bypass grafting surgery to evaluate the effect of avoiding cardiopulmonary bypass on perioperative patient outcome Diabetes mellitus was defined as glucose intolerance either treated dietary, with oral hypoglycemics or with insulin According to this definition of diabetes mellitus we found an overall prevalence of 371% (coronary artery bypass grafting with cardiopulmonary bypass: 375%; off-pump coronary artery bypass grafting: 325%) Eleven outcome variables having a significant association with diabetes were identified Diabetes could be identified as an independent predictor of postoperative delirium, renal dysfunction and respiratory insufficiency Prevalence of these three variables was lower in diabetics undergoing off-pump coronary artery bypass grafting as in those undergoing coronary artery bypass grafting with cardiopulmonary bypass surgery reaching statistical significance with regard to postoperative delirium and respiratory insufficiency In conclusion, diabetes mellitus is a significant independent predictor for three postoperative outcome variables in coronary artery bypass surgery Avoiding cardiopulmonary bypass in diabetics seems to have a beneficial effect

Anastomotic devices for coronary artery bypass grafting.

Abstract: With the advent of off-pump and minimally invasive coronary artery bypass grafting, efforts to facilitate construction of the graft to coronary anastomosis have increased. As a result, a number of anastomotic devices have been developed. While the ideal anastomotic device should be easy to use, produce a geometrically optimal anastomosis with minimal endothelial damage and minimal blood-exposed nonintimal surface, a number of design constraints apply. This review collects the available preclinical and clinical data for some of the devices, with special regard as to surgical outcome, patency rate and the need for additional perioperative anticoagulation treatment.

Totally endoscopic multivessel coronary artery bypass surgery using the da Vinci surgical system: a feasibility study on cadaveric models.

Abstract: Background: The aim of the study was to develop a totally endoscopic coronary artery bypass procedure for the treatment of multivessel disease (MVTECAB). Methods: Procedure development was conducted on 6 human cadavers with the da Vinci Surgical System. For aortic clamping, a transthoracic aortic clamp was applied. The proximal anastomoses of vein grafts were created transthoracically with the Corlink automated anastomosis device. The target vessels on the heart were exposed with a modified endoscopically applicable Starfish vacuum device. In 1 cadaver, the endo-sling and endoscopic fan retractors were studied for exposure support. Results: Harvesting of bilateral internal thoracic arteries was easily accomplished. Aortic clamping was easier from the right side. In the left-side approach, the proximal anastomoses were completed without leakage in all 3 cadavers. One incorrect deployment occurred, and the deployment needed to be redone. In the right-side approach, 1 proximal anastomosis was performed without leakage, and another needed to be repaired for incorrect deployment. The fan retractors either covered too much of the targeted area of the heart surface or did not provide good manipulation capabilities. The endo-sling enabled atraumatic exposure of the target vessels. The modified Starfish performed sufficiently for exposing target vessels. Problems were found with epicardial fat clogging the Starfish suction chamber and with bending of the suction tube neck, both of which resulted in a loss of tissue contact. Two of the cadavers approached from the left side were completely revascularized with 3 grafts, and 4 anastomoses were performed on the third cadaver. Triple-vessel revascularization was performed in the cadavers approached from the right side. Conclusion: This study demonstrates the feasibility of performing an MVTECAB on the arrested heart with the da Vinci Surgical System. Further procedure development is necessary to optimize the synergistic effects of the technologies used and to introduce this operation into clinical practice.

A novel adhesion barrier facilitates reoperations in complex congenital cardiac surgery

Abstract: OBJECTIVE Reoperations are associated with an increased surgical risk due to adhesions. We prospectively evaluated a bioresorbable membrane after surgery for congenital heart defects over a 3.5-year period. METHODS The surgical membrane (CV Seprafilm, Genzyme, Cambridge, Mass) was applied in 350 of 1024 patients; 30 of them underwent reoperation and were evaluated in comparison to 10 random reoperated patients. Adhesions were evaluated using a subjective scoring system [1 (lowest tenacity) to 5 (highest tenacity)] and extent in percent at different regions of the heart. RESULTS Patients were operated for atrioventricular septal defect (69), tetralogy of Fallot (65), functional single ventricle (75), valve surgery (48), ventricular septal defect (20), subaortic stenosis (17), hypoplastic left heart syndrome (17), and other diagnoses (39). Application of the surgical membrane was safe in all patients, without any infections. At reoperation patients received Glenn (14), total cavopulmonary connection (6), and others (10). Overall mortality was 2/350 (0.57%). There was a remarkable reduction in tenacity score (3.3 vs 4.3) and in the extent of adhesions (77.7% vs 86%). Duration of reoperation was significantly reduced. CONCLUSIONS A bioresorbable surgical membrane leads to a significant reduction in the tenacity and amount of adhesions. It is recommended for general use whenever repeat operation is anticipated in congenital as well as in adult cardiac surgery.

Gerüstfreie Mitralklappenprothese im Vergleich zu konventionellem Mitralklappenersatz oder Mitralklappenrekonstruktion nach fünf Jahren

Abstract: Seit August 1997 wurden 155 Patienten mit degenerativer Mitralklappenerkrankung untersucht. 53 Patienten (68±8 Jahre, 37 weiblich) der verglichenen Patienten erhielten eine Quattro™ mitral valve (St. Jude Medical Inc.) (QMV) und wurden mit 51 Patienten (69±9 Jahre, 32 weiblich) die eine Mitralklappenrekonstruktion (MKR) erhielten, sowie mit 51 Patienten (66±9 Jahre, 32 weiblich) nach konventionellem Mitralklappenersatz (MKE) verglichen. Die praoperative New York Heart Klassifikation war 3,1±0,6/2,9±0,5/2,9±0,6, Euroscore 4,7±2,1/4,4±1,9/4,2±2,6, linksventrikulare Ejektionsfraktion 64±12%/63±16%/61±14% und Cardiac Index 2,1±0,8l/min/m2/2±0,7l/min/m2/2±0,8l/min/m2 und zeigten keine signifikanten Unterschiede. Das mittlere Follow-up betragt 54±18 (11–79) Monate. Die Operationen wurde uber eine mediane Sternotomie (32 QMV/20 MKR/34 MKE) oder eine rechts anterolaterale Minithorakotomie (21/31/17) durchgefuhrt. Die Ischamiezeit betrug fur die QMV-Implantation 81±33 Minuten und lag damit signifikant hoher als den Kontrollgruppen. Der in der vorliegenden Untersuchung bestimmte mittlere Druckgradient uber der QMV von 4,8±1,9 mmHg und 4,3±1,4 mmHg in der MKE-Gruppe liegt im Bereich der Normalwerte fur Bioprothesen. Die Klappenoffnungsflachen waren bei den QMV-Implantationen, MKE-Implantationen und Mitralklappenrekonstruktionen postoperativ (2,9±0,7/ 3,2±0,8/3,3±0,8 cm2) und bei den Nachuntersuchungen (2,5±0,6/3±0,9/ 2,6±0,9 cm2) mit den Normwerten fur kunstliche Prothesen vergleichbar. Insgesamt konnten bis zu 89 Monate nach Implantation der QMV gute klinische und dopplerechokardiographische Ergebnisse im Vergleich zum konventionellen Mitralklappenersatz festgestellt werden. Somit kann nach Implantation einer QMV, eine standardisierte und ausreichende hamodynamische Funktion gewahrleistet werden. Die Fruhmortalitat der MKE-Gruppe (n=5) war signifikant hoher als in der QMV (n=1) und in der MKR-Gruppe (n=2). Reoperationen mussten bei 6 (QMV), 2 (MKR) und 3 (MKE) Patienten durchgefuhrt werden. Die Funf-Jahres-Uberlebensrate war mit 77,6±4,4% (QMV), 80,2±5,6% (MKE) und 82,6±5,6% (MKR) nicht signifikant verschieden und der altersgleichen regionalen Bevolkerung vergleichbar. Die mittelfristigen Ergebnisse nach QMV-Implantation sind viel versprechende. Die QMV stellt eine Alternative zum biologischen Mitralklappenersatz dar.