Showing papers by "Volkmar Falk published in 1999"

Stabilizer for robotic beating-heart surgery

Abstract: Surgical methods and devices allow closed-chest surgery to be performed on a heart of a patient while the heart is beating. A region of the heart is stabilized by engaging a surface of the heart with a stabilizer without having to stop the heart. Motion of the target tissues is inhibited sufficiently to treat the target tissues with robotic surgical tools which move in response to inputs of a robotic system operator. A stabilizing surface of the stabilizer is coupled to a drive system to position the surface from outside the patient, preferably by actuators of the robotic servomechanism. Exemplary stabilizers includes a suture or other flexible tension member spanning between a pair of jointed bodies, allowing the member to occlude a coronary blood vessel and/or help stabilize the target region between the stabilizing surfaces.

Performing cardiac surgery without cardioplegia

Abstract: A surgical system or assembly for performing cardiac surgery includes a surgical instrument (82); a servo-mechanical system engaged to the surgical instrument for operating the surgical instrument; and an attachment assembly for removing at least one degree of movement from a moving surgical cardiac worksite. The surgical system or assembly also includes a motion tracking system (88); and a control computer (34) engaged to the attachment assembly, the motion tracking system and to the servo-mechanical system for controlling movement of the attachment assembly and for feeding gathered information to the servo-mechanical system for moving the surgical instrument.

Prospectively randomized evaluation of stentless versus conventional biological aortic valves: impact on early regression of left ventricular hypertrophy.

Abstract: Background —The aim of this prospectively randomized study was to evaluate left ventricular hypertrophy and its regression after stentless versus conventional biological aortic valve replacement. Methods and Results —From March 1996 through April 1998, 180 patients were prospectively selected; 106 patients received a stentless aortic valve (SAV), and 74 received a conventional stented bioprosthesis (CSB). Of these patients, 95% and 96%, respectively, had aortic stenosis. Their mean age was 72.3 and 74.8 years, and there were no significant differences in left ventricular function, preoperative pressure gradients, and NYHA functional status. Aortic annulus diameter indexes were comparable at 13.46 (SAV) versus 13.55 (CSB) mm ( P =NS). Larger SAVs were implanted because of the oversizing technique. In-hospital mortality (n=3 and 1 for SAV and CSB) was not valve related. At follow-up, all patients were in NYHA class 1 or 2. Baseline end-diastolic left ventricular posterior wall thickness was 15.6 (SAV) and 14.8(CSB) mm ( P =NS) and decreased to 11.8 (SAV) and 13.2 (CSB) mm ( P 2 at baseline ( P =NS), whereas after 6 months, it was 141 (SAV) and 170 (CSB) g/m 2 ( P Conclusions —Regression of left ventricular hypertrophy occurs in all patients after aortic valve replacement but is significantly enhanced after SAV implantation. This possibly is due to improved transvalvular hemodynamics.

The evolution of minimally invasive valve surgery--2 year experience.

Abstract: Objectives: The aim of the study was to evaluate the evolution of Port-Access minimally invasive mitral valve surgery to a robot assisted video assisted solo surgery approach. Methods: One hundred and twenty-nine patients with non-ischemic mitral valve disease underwent 3D-video assisted mitral valve surgery via a 4 cm right lateral minithoracotomy using femoro-femoral bypass and endoaortic clamping. Transcranial Doppler and continuous transesophageal echocardiography were used to monitor placement and positional stability of the endoclamp. After the initial series (group I, n = 62), a simplified solo surgical technique using voice controlled robotic assistance for videoscope guidance was used in the last 67 patients (group II). Results: After an initial learning curve and modifications of catheter design, the procedure could be steadily redefined and simplified. In the last 67 patients, the procedure was completed without the need for an additional assistant as ‘solo surgery’. The mitral valve was repaired in 72 and replaced in all other patients. Duration of bypass and clamp time steadily improved during our study and in the most recent 67 patients average 107 ∠ 34 and 48 ∠ 16 min, respectively. The voice controlled robotic arm (AESOP 3000, Automated Endoscope System for Optimal Positioning) provided a stable and precise video image with excellent exposure of all valvular and subvalvular structures. Hospital mortality was high in the early series (mean survival 88.7% at 804 ∠ 35 days; 95% CI: 735‐873) and partially procedure related (aortic dissection in two patients). In group II, hospital mortality has declined to 3.0% (mean survival 97.0% at 568 ∠ 12 days; 95% CI: 553‐600). Conclusion: Port-Access minimally invasive mitral valve surgery has evolved to be a reliable video assisted technique with reproducible results. Surgery can now be performed almost in the same time as with conventional techniques. Robotic assistance has enabled a solo surgery approach. © 1999 Elsevier Science B.V. All rights reserved.

Quality of computer enhanced totally endoscopic coronary bypass graft anastomosis--comparison to conventional technique.

Abstract: Objective: Aims of the study were to develop an endoscopic technique to perform robot assisted coronary anastomoses, using a computer enhanced telemanipulator and to compare the quality of the anastomoses with those performed using a standard open technique. Methods: A surgical telemanipulator with two instrument arms and a central videoscopic arm was used to perform remote endoscopic coronary artery bypass grafting on isolated porcine hearts. The end effectors and the videoscope were placed through three 10 mm port incisions. All anastomoses (Cx to LAD) were performed using a double armed 7‐0 Prolene suture of 5 or 7 cm in length. All operations were performed remotely from the master console using ten times magnification, tremor filtering and 3:1 motion scaling. Initially 20 anastomoses were performed to develop and train the technique. Then, 20 robot-assisted anastomoses (group I) were compared with 20 anastomoses using a standard open parachute technique (group II). All anastomoses were checked for patency and leakage. Patency was confirmed by bench angiography. After fixation, all anastomoses were macroscopically evaluated for patency, intactness, alignment, intimal tears and dehiscence. Both angiographic and pathologic evaluations were performed with the examiners blinded to the technique of anastomosis. Results: In the initial feasibility series, time for anastomosis was 18.2 ∠ 9.1 min. All anastomoses were patent although minor stenoses were found in two and minor leakage was noted in five anastomoses. In the second series all anastomoses were patent, not leaking and showed a good run-off at angiography. Mean time for anastomosis in group I was 12.8 ∠ 2.4 min as compared with 6.3 ∠ 0.2 min in group II (P , 0.001), respectively. Macroscopic analysis demonstrated equal quality for both groups. There were no stenoses, no intimal tears and no dehiscences. All anastomoses had a normal alignment and intact suture lines. Conclusion: Using the Intuitive surgical telemanipulator, it is possible to remotely perform endoscopic coronary anastomoses with the same quality as with an open standard technique after a brief learning curve. This will enable true endoscopic coronary artery bypass grafting with a precision that has not been achieved with any other previously applied endoscopic technique. © 1999 Elsevier Science B.V. All rights reserved.

Dexterity enhancement in endoscopic surgery by a computer-controlled mechanical wrist

Abstract: SummaryThe use of conventional endoscopic instruments results in inaccurate and time-consuming techniques due to the limited range of motion. Telemanipulation systems may overcome these constraints. This study compares individual performance using a surgical tele-manipulator with either four or six degrees of freedom (DOF). Twenty non-professionals and 10 professionals (endoscopic surgeons; > 100 endoscopic procedures) performed a specially-designed set of tasks using the Intuitive Surgical tele-manipulation system at full capacity with six DOF, or in a reduced mobility mode with only four DOF (wrist-locked). Time and error rate for performing each task were assessed. In the non-professional group both time to perform the tasks and error rates were reduced when working with a six DOF system, as compared with the four DOF system. Dexterity enhanced by using the wrist reduced the time needed to complete a complex endoscopic task by 40%. In the professional group the time needed to perform the task was signi...

Comparison of MIDCAP versus conventional CABG surgery regarding pain and quality of life.

Abstract: BACKGROUND This prospective clinical trial focuses on pain and quality of life (QOL) after minimally invasive direct coronary artery bypass (MIDCAB) grafting versus conventional coronary artery bypass grafting (CABG). METHODS Group A consisted of 65 consecutive MIDCAB patients using an anterolateral mini-thoracotomy and the "off-pump" technique. Group B consisted of 95 computer-matched patients who underwent conventional CABG with cardiopulmonary bypass (CPB). Pain was graduated using the visual analog scale (VAS), and the verbal rating scale (VRS) [Troidl 1990]. QOL was evaluated at the time of discharge and three months after surgery using modified Nottingham Health Questionnaires that separate physical, social, activity, emotional, pain, and sleeping conditions. RESULTS Postoperative pain was higher after MIDCAB on postoperative day (POD) 1 (p< 0.002). From POD 4 onwards MIDCAB patients had less pain compared with the conventional group (p<0.04). MIDCAB patients required less pain medication from POD 4 onwards (p<0.05). QOL was significantly better in the MIDCAB group on POD 7 for physical (p< 0.038), activity (p< 0.016), pain (p< 0.041), and sleep (p<0.038) conditions. The three-month questionnaire showed significantly better levels for MIDCAB patients regarding physical (p< 0.03) and pain (p< 0.001) conditions, and a trend for activity (p< 0.08) and emotional (p<0.08) conditions. CONCLUSION Compared to patients undergoing conventional surgery, MIDCAB patients suffer more pain in the first three postoperative days, probably as a result of the lateral thoracotomy. From POD 4 onwards, MIDCAB patients are significantly better, experiencing less pain and showing better physical, activity, and sleeping conditions even three months after surgery. This can be attributed to the absence of median sternotomy and/or the avoidance of cardiopulmonary bypass.

Coronary bypass grafting without cardiopulmonary bypass--technical considerations, clinical results, and follow-up.

Abstract: BACKGROUND Coronary bypass surgery can be performed less invasively by avoiding cardiopulmonary bypass (CPB). We present our early 'off pump' coronary bypass surgery experience in combination with a minithoracotomy or sternotomy. METHODS Between 11/1996 and 12/1997 312 patients were included in a prospective study, 223 (Group A) underwent an antero-lateral minithoracotomy (MIDCAB) and 89 (Group B) had a full sternotomy (OPCAB). ITA harvesting and anastomosis was performed under direct vision in all cases. Different devices for local mechanical immobilization were used to perform the anastomosis. RESULTS In 212 patients of group A revascularization was by a single ITA graft and in 11 patients by a double graft using the radial artery as a T graft. Conversion to sternotomy and cardiopulmonary bypass was necessary in 12 (5.3%) patients. Intraoperative myocardial infarction was observed in 5 patients (2.2%). Early-postoperative reoperation due to graft failure was necessary in 5 patients (2.2%). Mortality was 0.4% (one patient). The early postoperative graft patency rate was 97.1% as confirmed by angiography. In group B, 25 patients had single graft and 64 patients multiple graft revascularization. Intraoperative conversion to CPB was necessary in 10 patients (11.2%). Intraoperative myocardial infarction occurred in 1 patient (1.1%), postoperative low output syndrome in 2 patients (2.2%). Early postoperative reoperation due to graft failure was necessary in 1 patient (1.1%). Mortality was 1.1%. Angiographic control of 48 patients after 6 months confirmed a patency rate of 92.6%. CONCLUSION Coronary bypass surgery without using cardiopulmonary bypass is safe to achieve good early and mid-term results. MIDCAB is a minimally invasive technique. Experienced surgeons should be ready to compete with PTCA techniques.

Indication and patient selection in minimally invasive and òff-pump' coronary artery bypass grafting.

Abstract: Background: The selection criteria to perform ‘off-pump’ coronary bypass (OPCAB) grafting are not well defined. The aim of this presentation is to outline the indications and the patient selection on the basis of 2 years experience with 572 OPCAB procedures. Materials and Methods: From November 1996 minimally invasive coronary bypass grafting was performed in 406 patients using a limited minithoracotomy for single left anterior descending artery (LAD) revascularization (group A). In 166 patients full sternotomy and OPCAB grafting for single or multiple vessel revascularization was performed (group B). Results: In group A the procedure could be performed ‘offpump’ together with a limited thoracotomy in 406 out of 457 patients (88.8%) who were scheduled for single graft revascularization to LAD. Exposure and quality of the LAD was good in 308/406 (76.0%) of the patients. The decision for sternotomy was made for different preoperative characteristics of these patients: Obese female patients 16/457 (3.5%), angiographic evidence of an intramyocardial running LAD 6/457% (1.4%), diffusely diseased and small LAD 11/457 (2.4%) severe COPD 3/457 (0.7%), unstable angina 11/457 (2.4%), emergency revascularization after failed PTCA 4/457 (0.8%). In 315/406 (77.8%) of the minimally invasive direct coronary artery bypass (MIDCAB)-patients exposure and quality of the LAD was good, in 97/406 (22.2%) moderate or even bad. In the latter subgroup stenosis free anastomosis was reduced (86.5%) compared to the subgroup of good exposure and quality with 98.3%. In group B selection for sternotomy and ‘off-pump’ procedure was made in 117/166 (70.4%) patients with a normal preoperative status (stable angina, ejection fraction . 35%) and with coronary lesions amenable for beating heart surgery (proximal RCA lesion . 80%, not calcified and well defined POD and marginal branches). In 49/166 (29.5%) decision for ‘off-pump’ procedure was made on the basis of a potential risk for cardiopulmonary bypass (CPB) such as acute myocardial infarction in 10/166 (6.0%), reduced ventricular function with EF , 35 in 28/166 (16.9%), calcified ascending aorta 4/166 (2.4%) or concomitant diseases 7/166 (2.5). Conclusion: To maintain excellent results after single LAD revascularization using the MIDCAB-approach, appropriate patient selection is crucial. Indication for sternotomy and ‘off-pump’ single LAD revascularization should made in those patients excluded for MIDCAB and in patients scheduled for multiple vessel-CABG who are at high risk for CPB (concomitant pulmonary, renal, neurological diseases or severely impaired left ventricular dysfunction) and have suitable target coronary arteries in term of location and quality. q 1999 Elsevier Science B.V. All rights reserved.

Early Clinical Results After Stentless Mitral Valve Implantation and Comparison With Conventional Valve Repair or Replacement

Abstract: Background —A new quadricusp stentless mitral bioprosthetic valve (QMV) is evaluated and compared with current standards. Methods and Results —Since August 1997, 67 patients were prospectively evaluated: 23 patients received a QMV, 23 had mitral valve repair (MVR), and 21 received conventional mitral valve replacement (MVP). Patient age was 69±8, 64±10, and 62±9 years for QMV, MVR, and MVP treatment, respectively. The underlying pathology was mitral stenosis, incompetence, and mixed disease in a corresponding 8, 9, and 6 patients for QMV, 1, 22, and 0 patients for MVR, and 2, 12, and 7 patients for MVP. The papillary muscles were sufficient in all QMV cases to suspend the valve. Cross-clamp time was 59±19 minutes for QMV implantation. In-hospital mortality for QMV, MVR, and MVP was 1, 0, and 0 patients, respectively, and thoracotomy had to be performed again in 1, 1, and 2 patients, respectively (these outcomes were not valve related). At baseline transthoracic echocardiography, respective maximum flow velocities were 1.6, 1.4, and 1.7 m/s, and valve orifice area was 2.6, 3.5, and 3.4 cm2. Mild transvalvular reflux was seen in 8, 7, and 2 patients; moderate reflux, in 1, 1, and 1 patients. Left ventricular ejection fraction was 52%, 54%, and 51% in the respective treatment groups. At follow-up, hemodynamic parameters had further improved in all groups. Conclusions —One year after clinical implantation, the QMV appears to function well and has no additional risks compared with MVR or MVP. The subvalvular apparatus is preserved by suspending the QMV at the papillary muscles; this arrangement is hemodynamically advantageous. Echocardiography reveals an excellent valve performance that resembles native mitral valve morphology and hemodynamic function. The QMV is a promising alternative for biological mitral valve replacement.

Effectiveness of different anticalcification treatments for stentless aortic bioprostheses.

Abstract: BACKGROUND: New anticalcification treatments for stentless bioprostheses have not yet been compared independently MATERIAL AND METHODS: The No-reacts (Biocor), AOA (Medtronic Freestyle), and BiLinx (SJM Toronto SPV II) methods were studied and compared with a control group Aortic valve leaflet and aortic root tissue was subcutaneously implanted in 60 male, 21-days-old Sprague-Dawley rats Calcium content was quantified using inductively coupled plasma spectrophotometry RESULTS: No infections occurred Low levels of calcium were measured in aortic valve leaflet tissue for all methods (04 to 15 mg/g dry weight) in comparison to the control group (225 mg/g), p < 001 Calcification of aortic root tissue was low in the Bilinx group (24 mg/g, p < 001), whereas calcium levels were high in all other groups (104 to 127 mg/g) CONCLUSIONS: Calcification of aortic valve leaflets was significantly reduced by all new anticalcification treatments, whereas aortic root calcification was only reduced by inhibition of cellular calcification (BiLinx) Maximum anticalcification properties of both leaflet and aortic root are important, as these are considered a functional unit in stentless bioprostheses

Quality assessment in minimally invasive coronary artery bypass grafting

Abstract: Objectives: The most important determinant for the success of minimally invasive coronary artery bypass grafting (MIDCAB) is the quality and long-term patency of the graft and anastomosis. Intra and postoperative quality assessment is important to confirm the safety and effectiveness of minimally invasive techniques. Methods: From January to December 1998 MIDCAB was performed in 246 patients using a limited minithoracotomy for single left anterior descending artery (LAD) revascularization. According to our standard protocol quality assessment of the graft and anastomosis consisted of intraoperative flow measurement, early postoperative angiography and follow-up angiography after 6 months. Results: Intraoperative flow measurement was performed in patients with anastomoses unsuitable for coronary probing (75/246, mean flow of 34:3 ^ 17:7 ml/min). Early patency was confirmed by intraoperative monoplane angiogram in 37/246 (15.0%) patients and by postoperative multiplan angiography in 205/246 (83.3%). Early patency rate was 98.0%. Six months follow-up showed a patency rate of 97.5% (one occluded graft, two severe and two moderate stenoses at the anastomotic site). Eighty-nine percent of the patients were in a CCS angina class I, 11% in class II, respectively. Six months mortality was 0.8%. Re-intervention had to be performed in 5/116 (4.3%). Conclusions: A standardized protocol for quality assessment is mandatory for MIDCAB surgery. The proposed algorithm serves to ensure the safety and effectiveness of this new technique. Our recent series document an excellent outcome of the MIDCAB approach. Postoperative multiplan angiography is the only technique to achieve valid information about the quality of graft and anastomosis. q 1999 Elsevier Science B.V. All rights reserved.

Quadrileaflet stentless mitral valve replacement.

Abstract: BACKGROUND The study evaluates clinical results and hemodynamic parameters one year after implantation of a stentless quadrileaflet mitral valve (QMV). METHODS Since August 1997 28 patients received the QMV, patient age was 69 +/- 8 years; 13 had predominant mitral stenosis and 15 incompetence, preoperative NYHA functional class was III or IV and cardiac index 1.8 +/- 0.6 L/min/m2. RESULTS Surgery was performed using a conventional (25) or a minimally invasive approach (3). 20 patients received a medium and 8 a large-size prosthesis, crossclamp time was 58 +/- 19 min. Additional procedures were myocardial revascularization in four, tricuspid repair in two, and left-atrial radiofrequency ablation to restore sinus rhythm in six patients. Perioperative mortality (1) was not valve-related. All other patients were discharged on time. At postoperative, 6-, and 12-months follow-up mean transvalvular pressure gradients were 4.2 +/- 1.5 / 4 +/- 0.9/ 3.8 +/- 1.4 mmHg and mitral valve orifice area index was 1.5 +/- 0.3 / 1.6 +/- 0.3 / 1.6 +/- 0.4, NYHA class was I or II. CONCLUSIONS The QMV is well suited for mitral valve replacement. The anulo-ventricular continuity is preserved and the QMV function resembles native mitral valve function. If its performance is maintained in the long term the QMV may be the mitral prosthesis of choice.