Trajectory of coronary motion and its significance in robotic motion cancellation

Objectives: To characterize remaining coronary artery motion of beating pig hearts after stabilization with an ‘Octopus' using an optical remote analysis technique. Methods: Three pigs (40, 60 and 65 kg) underwent full sternotomy after receiving general anesthesia. An 8-bit high speed black and white video camera (50 frames/s) coupled with a laser sensor (60 μm resolution) were used to capture heart wall motion in all three dimensions. Dopamine infusion was used to deliberately modulate cardiac contractility. Synchronized ECG, blood pressure, airway pressure and video data of the region around the first branching point of the left anterior descending (LAD) coronary artery after Octopus stabilization were captured for stretches of 8 s each. Several sequences of the same region were captured over a period of several minutes. Computerized off-line analysis allowed us to perform minute characterization of the heart wall motion. Results: The movement of the points of interest on the LAD ranged from 0.22 to 0.81 mm in the lateral plane (x/y-axis) and 0.5-2.6 mm out of the plane (z-axis). Fast excursions (>50 μm/s in the lateral plane) occurred corresponding to the QRS complex and the T wave; while slow excursion phases (<50 μm/s in the lateral plane) were observed during the P wave and the ST segment. The trajectories of the points of interest during consecutive cardiac cycles as well as during cardiac cycles minutes apart remained comparable (the differences were negligible), provided the hemodynamics remained stable. Inotrope-induced changes in cardiac contractility influenced not only the maximum excursion, but also the shape of the trajectory. Normal positive pressure ventilation displacing the heart in the thoracic cage was evident by the displacement of the reference point of the trajectory. Conclusions: The movement of the coronary artery after stabilization appears to be still significant. Minute characterization of the trajectory of motion could provide the substrate for achieving motion cancellation for existing robotic systems. Velocity plots could also help improve gated cardiac imagin

Accuracy of MSCT coronary angiography with 64-slice technology: first experience

Aims The aim of our study was to investigate the accuracy of 64-slice computed tomography (CT) for assessing haemodynamically significant stenoses of coronary arteries. Methods and results CT angiography was performed in 67 patients (50 male, 17 female; mean age 60.1±10.5 years) with suspected coronary artery disease and compared with invasive coronary angiography. All vessels ≥1.5 mm were considered for the assessment of significant coronary artery stenosis (diameter reduction >50%). Forty-seven patients were identified as having significant coronary stenoses on invasive angiography with 18% (176/1005) affected segments. None of the coronary segments needed to be excluded from analysis. CT correctly identified all 20 patients having no significant stenosis on invasive angiography. Overall sensitivity for classifying stenoses was 94%, specificity was 97%, positive predictive value was 87%, and negative predictive value was 99%. Conclusion Sixty-four-slice CT provides a high diagnostic accuracy in assessing coronary artery stenose

Tissue engineering of small caliber vascular grafts

Objective: Previous tissue engineering approaches to create small caliber vascular grafts have been limited by the structural and mechanical immaturity of the constructs. This study uses a novel in vitro pulse duplicator system providing a ‘biomimetic' environment during tissue formation to yield more mature, implantable vascular grafts. Methods: Vascular grafts (I.D. 0.5 cm) were fabricated from novel bioabsorbable polymers (polyglycolic-acid/poly-4-hydroxybutyrate) and sequentially seeded with ovine vascular myofibroblasts and endothelial cells. After 4 days static culture, the grafts (n=24) were grown in vitro in a pulse duplicator system (bioreactor) for 4, 7, 14, 21, and 28 days. Controls (n=24) were grown in static culture conditions. Analysis of the neo-tissue included histology, scanning electron microscopy (SEM), and biochemical assays (DNA for cell content, 5-hydroxyproline for collagen). Mechanical testing was performed measuring the burst pressure and the suture retention strength. Results: Histology showed viable, dense tissue in all samples. SEM demonstrated confluent smooth inner surfaces of the grafts exposed to pulsatile flow after 14 days. Biochemical analysis revealed a continuous increase of cell mass and collagen to 21 days compared to significantly lower values in the static controls. The mechanical properties of the pulsed vascular grafts comprised supra-physiological burst strength and suture retention strength appropriate for surgical implantation. Conclusions: This study demonstrates the feasibility of tissue engineering of viable, surgically implantable small caliber vascular grafts and the important effect of a ‘biomimetic' in vitro environment on tissue maturation and extracellular matrix formatio

Assessment of coronary sinus anatomy between normal and insufficient mitral valves by multi-slice computertomography for mitral annuloplasty device implantation

Introduction: Latest techniques enable positioning of devices into the coronary sinus (CS) for mitral valve (MV) annuloplasty. We evaluate the feasibility of non-invasive assessment to determine CS anatomy and its relation to MV annulus and coronary arteries by multi-slice CT (MSCT) in normal and insufficient MV. Methods: Fifty patients (33 males, 17 females, age 67±11 years) were studied retrospectively by 64-MSCT scans for anatomical criteria regarding CS and its relation to MV annulus and circumflex artery (CX). We included 24 patients with severe mitral insufficiency and 26 with no MV disease. Diameter of MV, of proximal and distal ostium of CS, length and volume of CS, angle between anterior interventricular vein (AIV) and CS, caliber change of CX before, under/over and after CS were analysed. Different anatomical correlations were demonstrated: distance of MV annulus to CS, CX to CS. Results: Diameter of proximal CS ostium was significantly larger in insufficient MV compared to normal MV (11±2.8mm vs 9.9±2.5mm; p<0.024). CS was significantly longer in patients with insufficient MV (125.4±17mm vs 108.9±18mm; p<0.003) with also significant differences in volume of CS (p<0.039). Significant difference in annulus diameter, 46.1±6mm (insufficient MV) versus 39.5±7.5mm, p<0.004 was observed. Angle CS-AIV was 103.5±29° (range 52°-144°) in insufficient valves versus 118.2±24.5° (range 73°-166°) in normal valves with a tendency to higher angles in normal valves (p=0.06). Distance of MV annulus to CS measured 16±4.1/14.2±3.6mm (insufficient/normal MV) without significant difference between groups. In 15 patients CX ran under CS. Eighty-four percent of these patients (13/15) show a decrease in CS caliber in the area of intersection. In 14 patients CS ran over and in one patient the diameter of the CS at intersecting region was smaller. In 16 patients no direct point of contact was visible, in five patients CX to CS positioning was not evaluable. Conclusion: There is a significant anatomic difference between normal and insufficient MV, which might be the basis for any interventional approaches through the CS. Exact measurements of all structures and its anatomic correlations are possible with MSCT, which allows pre-interventional plannin

Modified ultrafiltration lowers adhesion molecule and cytokine levels after cardiopulmonary bypass without clinical relevance in adults

Objective: Cardiac surgery with cardiopulmonary bypass (CPB) results in expression of cytokines and adhesion molecules (AM) with subsequent inflammatory response. The purpose of the study was to evaluate the clinical impact of modified ultrafiltration (MUF) and its efficacy in reducing cytokines and AM following coronary artery bypass grafting (CABG) in adults. Methods: A prospective randomized study of 97 patients undergoing elective CABG was designed. Fifty patients were operated on using normothermic and 47 patients using hypothermic CPB. The normothermic group was subdivided into a group with modified ultrafiltration (n=30) and a group without MUF (n=20). In the hypothermic group 30 patients received MUF compared to 17 patients serving as controls. MUF was instituted after CPB for 15 min through the arterial and venous bypass circuit lines. Cytokines (IL-6, IL-8, TNF-α, IL-2R) and adhesion molecules (sE-selectin, sICAM-1) were measured preoperatively, pre-MUF, in the ultrafiltrate, 24 h, 48 h and 6 days after surgery by chemiluminescent enzyme immunometric assay or enzyme-linked immunosorbent assay (ELISA). Clinical parameters were collected prospectively until discharge. Results: In all patients AM and cytokines were significantly elevated after normothermic and hypothemic CPB. AM and cytokines were significantly higher in hypothermia compared to normothermia. In hypothermic CPB sE-selectin was decreased after 24 h by 37% (P<0.0063) and by 40% (P<0.0027) after 48 h postoperatively. ICAM-1 was reduced by 43% (P<0.0001) after 24 h and by 60% (P<0.0001) after 6 days. Similar results were seen in cytokines with reduction up to 60% after 24 h. Changes after 48 h were noticeable but not significant. Reduction of AM and cytokines after normothermic CPB was minimal. Neither in normothermia, nor in hypothermia has sIL-2R been effectively removed from the circulation. There were no significant differences in the clinical variables between the patients with or without MUF. Conclusion: AM and cytokines are significantly elevated after hypothermic CPB compared to normothermic CPB. MUF led to a significant reduction in cytokine and AM levels after hypothermic CPB, except for IL-2R. MUF showed minimal effect in normothermia. We conclude that MUF is an efficient way to remove cytokines and AM. However, we were unable to demonstrate any significant impact of MUF in outcome of adults after elective CAB

Feasibility of the Engager™ aortic transcatheter valve system using a flexible over-the-wire design

OBJECTIVES The aim was to investigate the safety and feasibility of the redesigned Engager™ transcatheter aortic valve implantation (TAVI) system. METHODS Transapical aortic valve implantation with the Engager™ valve prosthesis was intended in 11 patients, and performed in 10. Endpoints were defined according to the valve academic research consortium recommendations for reporting outcomes of TAVI in clinical trials. RESULTS All 10 patients were implanted successfully. No devicerelated or delivery system complications like coronary obstruction or aortic dissection emerged. One patient (10%) died from non-device-related reasons at post-operative day 23 of multi-organ failure. The invasively measured peak-to-peak gradient after valve implantation was 7.1±3.5mmHg. In 90%, there was no or only trivial (≤grad I) aortic regurgitation due to paravalvular leakage. In 10% of the patients, aortic regurgitation grade I-II was observed. At 30-day follow up, the mean gradient was 15.6±4.9mmHg, and no more than a mild transvalvular and paravalvular aortic regurgitation was seen as assessed by transthoracic echocardiography. CONCLUSIONS Application of the Engager™ TAVI system is safe and feasible. Prosthesis deployment in an anatomically correct position was facilitated by the design of the valve prosthesis and was successful in all patients. No device or delivery-system-related complications emerged. Safety and feasibility endpoints were met. Good results concerning the aortic valve performance after implantation and at 30-day follow up were ascertained. These results encouraged the start of a European Pivotal trial including patients to dat

Is off-pump superior to conventional coronary artery bypass grafting in diabetic patients with multivessel disease?

Objective: Diabetic patients often present with diffuse coronary disease than nondiabetic patients posing a greater surgical challenge during off-pump revascularization. In this study, the safety, feasibility, and completeness of revascularization for this subset of patients was assessed. Methods: From 2002 to 2008, 1015 diabetic patients underwent myocardial revascularization. Patients received either off-pump coronary artery bypass (OPCAB; n=540; 53%) or coronary artery bypass grafting (CABG; n=475; 47%). Data collection was performed prospectively and data analysis was done by propensity-score (PS)-adjusted regression analysis. Primary endpoints were mortality, major adverse cardiac and cerebrovascular events (MACCEs), and a composite endpoint including major noncardiac adverse events (MNCAEs) such as respiratory failure, renal failure, and rethoracotomy for bleeding was applied. An index of complete revascularization (ICOR) was defined to assess complete revascularization by dividing the total number of distal anastomoses by the number of diseased vessels. Complete revascularization was assumed when ICOR was >1. Results: OPCAB patients had a significantly lower mortality-rate (1.1% vs 3.8%; propensity-adjusted odds ratio (PAOR)=0.11; p=0.018) and displayed less frequent MACCE (8.3% vs 17.9%; PAOR=0.66; p=0.07) including myocardial infarction (1.3% vs 3.2%; PAOR=0.33; p=0.06) and stroke (0.7% vs 2.3%; PAOR=0.28; p=0.13). Similarly, a significantly lower occurrence of the noncardiac composite endpoint (MNCAE) (PAOR=0.46; confidence interval (CI) 95% 0.35-0.91; p1 was achieved clearly indicating complete revascularization (94.3% vs 93.7%; p=0.24). Conclusions: OPCAB offers a lower mortality and superior postoperative outcomes in diabetic patients with multivessel disease. Arterial grafts are used more frequently that may contribute to better long-term outcomes and the OPCAB approach does not come at the cost of less complete revascularizatio