Minimally Invasive Cardiac Surgery Research Articles

ANALYSIS OF THE PHYSICAL BEHAVIOR OF A HOOKED TITANIUM BASED PERCUTANEOUS AORTIC VALVE STENT

Vascular support structures are important devices for treating valve stenosis. Large population of patients is treated for valvular disease and the principal mode of treatment is the use of percutaneous valvuloplasty. Stent devices are proving to be an improved technology in minimal invasive cardiac surgery. This technology now accounts for 20% of treatments in Europe. This new technology provides highly effective results at minimal cost and short duration of hospitalization. During the development process, a number of specific designs and materials have come and gone, and a few have remained. Many design changes were successful, and many were not. This paper discusses the physical behavior of a hooked percutaneous aortic valve stent design using finite element analysis using a new Titanium alloy. The analysis performed in this paper may aid in understanding the stent's displacement ranges when subjected to the physiological pressures exerted by the heart and cardiac blood flow during abnormal cardiovascular conditions. It may also help to evaluate the suitability of a new titanium alloy for fabrication purposes.

Nursing management in robotic minimally invasive cardiac surgeries

Objective To observe the clinical application of robotic (da Vinic S) minimally invasive cardiac surgeries and to summarize the method of the nursing management.Methods 431 patients accepted robotic minimally invasive cardiac surgeries from January 2007 to July 2011. The preoperative preparation,nursing cooperation during operation and postoperation management was retrospectively analyzed.Results With effective preoperative preparation,nursing cooperation during operation and postoperation management,all 431 cases of robotic cardiac surgeries were successful. No thoracotomy was carried out during operation.Duration of preparation and operation was significantly shorter than before.Conclusions Sufficient preoperative preparation,practiced nursing cooperation during operation and proficient machine manipulation are prerequisite to the implementation of robotic cardiac surgery. Key words: Cardiac surgery; Nursing management research; Robotic surgery

Evolution of Cannulation Techniques for Minimally Invasive Cardiac Surgery a 10-Year Journey

For minimally invasive cardiac surgery (MICS) procedures requiring cardiopulmonary bypass (CPB), cannulation techniques vary and seem to be important determinants of technical difficulty and clinical outcomes. Over 10 years of MICS, we have modified our techniques substantially, and the present report outlines the evolution of our current cannulation platform. From October 2000 to November 2010, 1087 minimally invasive cardiac procedures were performed at our institution; of these, 165 were done without CPB and were excluded. Methods of arterial and venous cannulation and aortic occlusion were retrospectively reviewed. Outcomes of interest included CPB and aortic cross-clamp time, as well as rates of in-hospital stroke, myocardial infarction, and short- and long-term mortality. The mean age of the study population was 57 ± 15 years, with 50% being men. The MICS procedures included mitral valve surgery, atrial septal defect repair, atrial fibrillation ablation, and cardiac tumor resections. Over the study period, peripheral arterial cannulation was replaced by central aortic cannulation, which was used in 33% of patients in 2000-2001 and 93% in 2008-2010. Venous cannulation strategies also evolved over time, from percutaneous neck and femoral (78% of cases from 2000-2005), to direct superior vena cava and percutaneous femoral (67% in 2006-2007), to percutaneous dual-stage femoral (51% in 2008-2010). Aortic occlusion was achieved by endoaortic balloon in 33% of cases in 2000-2001 but, by 2002, was replaced by transaxillary clamp occlusion and direct antegrade/retrograde cardioplegia. In the post-endoballoon era, CPB and cross-clamp times have remained consistent. Overall, there were nine strokes (<1.0%), no myocardial infarctions, and 18 deaths (2.0%) within 30 days of surgery, and the incidence of these outcomes has not changed over time. Over 10 years, our cannulation strategy for MICS has evolved to favor central aortic over femoral arterial cannulation, percutaneous femoral dual-stage bicaval venous drainage over percutaneous neck access, and transaxillary clamping over endoaortic balloon occlusion of the aorta. In our experience, this approach has resulted in low complication rates and a reliable platform for a variety of MICS procedures.

Excision of a left atrial myxoma via a minimally-invasive technique: a possible routine access

We would like to present our experience of surgical excision of intracardiac tumors using a video-assisted minimally-invasive cardiac surgery (MIC) technique. An 83-year-old female patient received video-assisted cardiac surgery for excision of a left atrial tumor. The surgery was performed through a right anterior submammary minithoracotomy and guided by video-assisted endoscopic techniques by projected images on a video monitor while under femoro-femoral bypass. The myocardium was protected by single-dose antegrade crystalloid cardioplegia. The tumor was excised completely recording a 61-minute bypass time and a 103-minute total operative time. Histopathological examination revealed left atrial myxoma. Transthoracic echocardiography examination showed good ventricular function and the absence of residual tumors. The patient was satisfied by the cosmetic healing of the wound and was discharged eight days after the surgery. Video-assisted MIC surgery is technically feasible and could be applied as a routine access in all left atrial tumors without the fear of inadequate intraoperative exposure and its drawbacks.

Repair of traumatic tricuspid insufficiency via minimally invasive port access

We report on a successful tricuspid valve plasty using port-access minimally invasive cardiac surgery (MICS) for severe traumatic tricuspid insufficiency caused by blunt chest trauma suffered 15 years previously. A combination repair procedure, consisting of cleft closures, plication of the anteroseptal commissure, and ring annuloplasty, was necessary to achieve valve competence and proved possible via port access without difficulty. Port-access MICS is an alternative approach for tricuspid valve surgery.

Eight‐Year Experience with Minimally Invasive Cardiothoracic Surgery

BackgroundOver the past decade, minimally invasive cardiac surgery (MICS) has emerged as an accepted approach for the management of cardiac disease that requires a surgical solution. We report the results of an 8-year, single-institution experience with MICS.MethodsBetween January 1, 2000 and December 31, 2007, a total of 910 patients underwent MICS. Major cases included aortic valve procedures (71, 7.8%), coronary artery bypass grafting (96, 10.5%), atrioseptal defect repair (103, 11.3%), and mitral valve procedures (507, 55.7%). Major outcomes of interest included the complication and mortality rates.ResultsThe mean age of the patients was 57 ± 15 years; the mean ejection fraction was 55% ± 11%; and the mean body mass index was 26.1 ± 4.9. Overall, 782 cases (85.9%) were performed through a mini-thoracotomy. Most of the cases were accomplished through central cannulation (765, 84.0%), and venous drainage was most commonly performed in a bicaval fashion (percutaneous superior vena cava and percutaneous inferior vena cava). The mean aortic cross-clamp and cardiopulmonary bypass (CPB) times were 58.1 ± 44.9 and 101.9 ± 66.8 min, respectively. Conversion to full sternotomy occurred in 10 patients, and the median length of stay in hospital was 6 days. The overall complication rate was 8.8%, and the 30-day mortality rate was 2.9%. In the multivariate logistic regression analysis, risk factors associated with in-hospital complications included age, CPB time, arterial cannulation location, conversion from off-CPB to on-CPB, hepatic insufficiency, and diabetes. In the multivariate hazards regression analysis, risk factors associated with mortality included postoperative stroke, renal failure, and sternal wound infection; CPB time; and previous surgery.ConclusionsIn our experience, minimally invasive approaches are effective and reproducible for a variety of cardiac operations, with acceptable operating time durations, morbidity, and mortality.

Biomaterial optimization in a percutaneous aortic valve stent using finite element analysis

Vascular support structures are important devices for treating valve stenosis. Large population of patients are treated for valvular disease and the principal mode of treatment is the use of percutaneous valvuloplasty. Stent devices are proving to be an improved technology in minimal invasive cardiac surgery. This technology now accounts for 20% of treatments in Europe. This new technology provides highly effective results at minimal cost and short duration of hospitalization. This paper discusses the design and finite element analysis (FEA) of a percutaneous aortic valve stent. The stent design was modeled and subjected to FEA. The improved model design was carried out to meet the functional and surgical requirements. Analysis was done with different materials with loads ranging from 50 to 73 kgf/mm(2). These forces were selected because these values are far greater than the normal human blood pressure which ranges from 10 to 16 kPa. It was also to understand the mechanical behavior of different stent materials under such high pressures. A stent model was generated and its physical, mechanical, and behavioral properties were studied. Finite element analysis and simulation of the model help the designer to optimize the geometry suitable for performance during and after implantation. The design objective for the stent is to have long-term durability, low thrombogenicity, and resistance to migration and paravalvular leak. The analysis performed in this paper may aid in understanding the stent's tolerable pressure ranges in comparison with the physiological pressures exerted by the heart and cardiac blood flow during abnormal cardiovascular conditions. It may also help in finding the material that will best suit the stent.

The future of minimally invasive cardiac surgery

The ultimate goal of minimally invasive cardiac surgery (MICS) is the perfection of totally endoscopic cardiovascular surgery, without the need for thoracotomy; instead opening a number of access apertures ( ≤1 cm), and treatimg cardiovascular conditions using only the endoscope and narrow instruments. The first step on the road to minimally invasive surgery was endoscopic cholecystectomy, commenced in earnest in America and Europe in 1988. This minimally invasive method of removing the gall bladder laparoscopically, without the need for laparotomy, has a high level of patient satisfaction attributable to decreased postoperative pain, better cosmetic appearance due to the lack of a laparotomy scar, and earlier recovery, discharge and return to activities. The introduction of minimally invasive surgery techniques to cardiovascular surgery have been extremely difficult, however, due to the need to manipulate the heart and aorta, usually under cardiopulmonary bypass (CPB), and technical difficulties with endoscopic surgery. Following training and animal experiments, in July 1992 we successfully performed the first endoscopic interruption of patent ductus arteriosus. 1) This success was

Subject-specific models for image-guided cardiac surgery

Three-dimensional visualization for planning and guidance is still not routinely available for minimally invasive cardiac surgery (MICS). This can be addressed by providing the surgeon with subject-specific geometric models derived from 3D preoperative images for planning of port locations or to rehearse the procedure. For guidance purposes, these models can also be registered to the subject using intraoperative images. In this paper, we present a method for extracting subject-specific heart geometry from preoperative MR images. The main obstacle we face is the low quality of clinical data in terms of resolution, signal-to-noise ratio, and presence of artefacts. Instead of using these images directly, we approach the problem in three steps: (1) generate a high quality template model, (2) register the template with the preoperative data, and (3) animate the result over the cardiac cycle. Validation of this approach showed that dynamic subject-specific models can be generated with a mean error of 3.6 ± 1.1 mm from low resolution target images (6 mm slices). Thus, the models are sufficiently accurate for MICS training and procedure planning. In terms of guidance, we also demonstrate how the resulting models may be adapted to the operating room using intraoperative ultrasound imaging.

Video-assisted minimally invasive cardiac surgery for atrial fibrillation: a report of 57 cases

To evaluate the feasibility and the efficacy of a new video-assisted minimally invasive surgery for patients with atrial fibrillation (AF). From December 2006 to October 2007, 57 patients who were 56.4 years old in average underwent the video-assisted minimally invasive cardiac operation for AF, and there were 40 male patients. Thirty-eight patients were paroxysmal AF, 7 patients were persistent and 12 patients were long-standing persistent. Three patients had failed catheter ablation, and two patients had preoperative permanent pacemaker implantation. All patients went under the minimally invasive procedure. Intraoperative electrophysiological mapping were performed. Mean operation time was 3.5 h. One patient was confirmed of left auricle thrombus, and one received concurrent epicardial cardiac resynchronization therapy during the procedure. There were no perioperative deaths. Acute respiratory failure occurred in 1 patient and acute heart failure in 1 patient after operation. Sixteen patients had electrical cardioversion after operation and during follow-up. At discharge, 78.9% (45/57) of all patients were in sinus rhythm (84.2% for paroxysmal AF, 71.4% for persistent AF, 66.7% for long-standing persistent AF). The patients were followed-up by 1 to 10 months. At 1 month after operation, overall 64.3% (36/56) were in sinus rhythm (67.6% for paroxysmal AF, 57.1% for persistent AF, 58.3% for long-standing persistent AF). At 3 months, overall 83.9% (47/56) were in sinus rhythm (86.5% for paroxysmal AF, 85.7% for persistent AF, 75.0% for long-standing persistent AF). At > or = 6 months, overall 87.0% (20/23) were in sinus rhythm (89.5% for paroxysmal AF, 75.0% for persistent AF). No thromboembolic event was observed during follow-up period. The video-assisted minimally invasive cardiac surgery proves to be safe, less traumatic, and presents optimistic early outcomes for paroxysmal AF patients.

Minimally Invasive Cardiac Surgery

Traditional cardiac surgery has been performed via a "big" median sternotomy incision by significant complexity and invasiveness. The traditional big incision has presented with many problems, and at the same time, has given opportunity to make the procedures less invasive. During the past decade, improvement in endoscopic equipments and operative techniques has resulted in development of minimal invasive cardiac operations using small incisions with or without robotics. A number of cardiac procedures are currently performed by minimal invasive approaches and for many surgeons a minimal invasive cardiac surgery has become a standard practice. Herein, we reviewed the minimal invasive cardiac surgery in the aortic valve, mitral valve, tricuspid valve, atrial septal defect, and coronary artery disease.

Vacuum-assisted venous drainage in extrathoracic cardiopulmonary bypass management during minimally invasive cardiac surgery

The diffusion of minimally invasive cardiac surgery (MICS) during open-heart surgery has increased the use of assisted venous drainage support for cardiopulmonary bypass (CPB). Peripheral cannulation with small cannulae and vacuum-assisted venous drainage (VAVD) during MICS has been adopted in our institution since 1998. After the Heartport technique (HP) experience, the trans-thoracic clamp technique is now currently used. The aim of this study is to report our experience with extrathoracic CPB with VAVD application (on CPB) during open-heart MICS. From October 1999 to June 2006, 193 patients underwent MICS. Thirty-seven (19.2%) patients were treated with the HP--13 (35%) with robotic technology and 156 (80.8%) with trans-thoracic aortic clamping (TTAC). Mean age was 39 years (range: 12-77), and 114 patients (59.1%) were female. A total of 128 patients (66.3%) underwent mitral valve surgery, 57 (29.6%) atrial septal defect closure, five (2.6%) cardiac mass removal, and three (1.5%) tricuspid valve repair. Four patients (2.0%) had a previous cardiac procedure. Peripheral CPB was established with a standard coated circuit. A 14 Fr arterial cannula was inserted into the right jugular vein and positioned at the atrial/superior vena cava junction. A 21 or 28 percutaneous femoral cannula, depending on body surface area, was inserted in the femoral vein and an arterial cannula in the right femoral artery. Gravitational drainage was combined with VAVD. To improve the safety and effectiveness of this technique, we monitored the pressure on each venous cannula and in the reservoir. The mean CPB time was 74.8 +/- 30 min (TTAC) and 119 +/- 48 min (HP); mean aortic clamping time was 51 +/- 19 min (TTAC) and 73 +/- 29 min (HP). We did not record any neurological complication. Two patients (1.0%), one from each group, were converted to sternotomy. Three patients (1.5%) underwent re-exploration for bleeding. In-hospital mortality was 0.5% (N = 1) (HP). Mechanical ventilation time and intensive care unit stay were comparable to those recorded with conventional sternotomy. In conclusion, we found that extrathoracic CPB and VAVD during trans-thoracic clamping is a safe, simple, and effective technique for MICS. However, there is a potential risk of haemolysis and air embolism, which can be prevented with vacuum monitoring, and with the addition of gravitational drainage to reduce vacuum pressure.

Minimally Invasive Cardiac Surgery(MICS)における陰圧吸引補助脱血法(Vacuum Assisted Venous Return：VAVR)の検討

Minimally Invasive Cardiac Surgery(MICS)における陰圧吸引補助脱血法(Vacuum Assisted Venous Return：VAVR)の検討

Sci-PM Thurs - 07: Registration of geometric cardiac models to magnetic resonance images

Minimally invasive cardiac surgery (MICS) has already been shown to reduce hospital stays, but the full potential is not yet realized, largely due to limitations in pre‐ and intra‐operative visualization inside the closed chest. To address these issues, we are developing the Virtual Cardiac Surgery Platform (VCSP) — a 4D (3D + time), virtual reality model of the patient specific thorax, derived from pre‐procedural images. In this abstract, we discuss the accuracy of our image registration‐based method for deforming geometrical template models of the heart sub‐anatomy (myocardium, right atrium + ventricle, left atrium + aorta, epicardium) to 10 different volunteers (“patients”). The template models are built by manually segmenting a high quality magnetic resonance(MR)image (this template image is an average of 20 acquisitions of the same volunteer, 1.53 mm3 voxels). The template image is mapped to a much lower quality patient image (1.5×1.5×6.0 mm3 voxels) obtained in a clinically feasible manner, by maximizing the normalized mutual information (NMI) between the two images. The resulting global (affine) and local (free form deformation) transformation is applied to one of the four template models to transform it into patient space. The registration accuracy is assessed by comparing the mapped template to the manual segmentation of the patient. On average, the customization process is accurate to within 2.4 ± 0.2 mm, whereas, the difference between two manual segmentations (gold standards) was 1.3 ± 0.2 mm. We believe our method adequately prepares templates for use within VCSP, prior to and during MICS.

Arterial Injuries from Femoral Artery Cannulation with Port Access Cardiac Surgery

Although minimally invasive (MI) cardiac surgery reduces blood loss, hospital stay, and recovery time, some MI approaches require femoral arterial cannulation, which introduces a heretofore unknown risk of femoral arterial injury. This study was performed to examine the risk of femoral arterial injury after Port Access MI cardiac surgery (PA-MICS) with femoral cannulation. Data were prospectively obtained on 739 consecutive patients who had PA-MICS with femoral cannulation between June 1996 and April 2000, identifying any patient with new (<30 days postoperative) arterial insufficiency from the cannulation site. Patient characteristics (gender, age, height, weight, body surface area, smoking, peripheral vascular disease, diabetes) and operative variables (cannula size, cross-clamp time) were examined with univariate and multivariate analysis to identify risk factors for arterial injury. Injuries were defined and classified by radiologic and intraoperative assessment, and follow-up was obtained by patient examination and from the medical records. Femoral arterial occlusion (FAC) occurred in 0.68% (5/739) of patients (4 women, 1 man; age range 26-74 years). The risk of femoral injury was higher in women: 1.31% vs 0.23% (p = 0.07). One patient had intraoperative limb ischemia from iliofemoral dissection and was treated by axillopopliteal bypass. Four patients presented postoperatively with claudication. Three of these had iliofemoral arterial occlusion or localized iliofemoral dissection and were treated with iliofemoral bypass, and 1 patient had localized femoral artery stenosis treated by angioplasty. With a mean follow-up of 17.8 months (range 13-26 months) limb salvage was achieved in all patients. Secondary or tertiary interventions were required in 40% (2/5), both in patients with iliofemoral occlusion, and 1 patient (20% of femoral injuries, 0.135% of overall series) has chronic graft occlusion and long-term claudication. The risk of arterial injury after femoral arterial cannulation and perfusion for Port Access surgery was low (0.68%). This risk is increased in women and is unpredictable. Initial vascular repair has a significant failure rate, and secondary interventions are often necessary. Although the femoral cannulation and perfusion technique is safe overall, the risk must be clearly recognized.

Myocardial Protection Using HTK Solution in Minimally Invasive Mitral Valve Surgery

Minimally invasive cardiac surgery (MICS) is a safe and satisfactory approach used mainly in mitral valve surgery with excellent results in many centers. Cardioplegia administration can be still a problem, especially when an endoaortic clamp is used. We retrospectively analyzed our early results with histidine-triptophane-ketoglutarate (HTK) solution used for myocardial protection in MICS. Between February 2003 and February 2004, 8 patients underwent mitral valve surgery using an endo- cardiopulmonary bypass (CPB) system and HTK solution as myocardial protection. The mean patient age was 67.7 +/- 9.2 years, and the preoperative ejection fraction was normal in all patients. Three patients had valve repair and 5 had valve replacement. Mean CPB time was 129.2 +/- 19.4 minutes, and aortic cross-clamp duration was 88.5 +/- 15.4 minutes. In every case HTK solution was used for only a single dose for cardioplegia at the beginning of the procedure, without any recalls. The heart restarted spontaneously at reperfusion in 6 of 8 cases (75%), and there were no significant modifications in electrocardiogram results or myocardial cytonecrosis enzymes (creatine kinase and its MB fraction) during the postoperative period. HTK solution is a cold crystalloid cardioplegia solution that has demonstrated its utility in MICS because it provides a safe long cardioplegic arrest time and it reduces the risk of inadequate coronary perfusion due to dislodgement of the endoaortic clamp.

FEASIBILITY STUDY OF A DIRECT ENDO-AORTIC CLAMP BALLOON FOR MICS -ESTABLISHMENT OF BALLOON FIXATION DURING CPB

Objective: MICS (Minimally Invasive Cardiac Surgery) has recently become an important concept in cardiac surgery. As the Heartport® port-access system under fluoroscopy is complicated, we developed a balloon which can be directly inserted easily and safely into the ascending aorta, and measured the balloon and perfusion pressure of CPB for preventing migration. Methods: We performed CPB with the balloon in twelve dogs (20 kg). Thoracotomy was performed, the ascending aorta was confirmed, and the outer diameter was measured. We cannulated into the femoral artery and into the right atrium for the CPB, inserted a root cannula and then EAC balloon, and inflated the balloon while confirming the internal pressure of the balloon. Then, the position of the balloon was confirmed while paying attention to systemic pressure and root pressure, and cardioplegia was injected. The pump pressure was progressively changed (50 mg, 80 mg, 90 mg), each balloon pressure was measured three times during one hour, and migration of the balloon was estimated. In addition, the histology at the fixed part of the balloon of the aorta was reviewed. Results: At the balloon pressure of 300–400 mmHg, the balloon migrated more than 100 mmHg. In all dogs, the balloon was inserted into the best position without fluoroscopy, and there was almost no histological difference between the endo-aortic clamp balloon compared with an extra-aortic clamp balloon. Conclusions: A new balloon was developed which can be easily and safely used, and which has potential for use in children.

Intensive imaging assessment for successful minimally invasive cardiac surgery.

To clarify special imaging assessment that is useful for minimally invasive cardiac surgery (MICS), we examined 141 cases of MICS operations with ministernotomy or minithoracotomy. In the 141 patients, 62 valve, 42 coronary, 37 congenital heart, and 2 other procedures were successfully completed without conversion to full sternotomy. Preoperative chest x-ray, computed tomography, and/or magnetic resonance imaging were necessary for determining the level of ministernotomy, especially in aortic valve operations. Transthoracic echocardiography was useful for selecting procedures of mitral valve or intracardiac repair through the MICS approach. Intraoperative transesophageal echocardiography was essential for continuous monitoring of cardiac function, intracardiac flow, air bubbles, and so forth. The above results suggest that intensive imaging assessment might be very important for successful MICS operations with ministernotomy or minithoracotomy and that extensive indications for this technique exist for various cardiovascular diseases.

A Flight from Minneapolis to Munich

Because minimally invasive cardiac surgery (MICS) requires enabling technology, the medical industry and device companies readily participated in the development of equipment to improve the performance of MICS. The excitement generated by the rapid introduction of new techniques and technology, cost benefit of eliminating cardiopulmonary bypass in patients with significant comorbid risk factors, and the decrease in tissue trauma of minimally invasive surgery even with the use of cardiopulmonary bypass, generated the scheduling of multiple international meetings. These meetings, often supported by funds contributed by the medical industry, were unsupervised and the core curriculum was not audited. Additionally, individual companies held their own symposia in an effort to popularize devices as well as market their own products. Data were scarce and prospective trials relating to the scientific evaluation of the minimally invasive processes were limited, casting pallor over the development of MICS.

Invited Commentary

Invited Commentary