Autologous or bovine pericardium for aortic cusp replacement? Histomorphological and biomechanical properties as decision making tools

Background/Introduction

Aortic valve cusp replacement using autologous pericardium is a promising technique. Expected advantages are reduced immune response, proper biomechanics and lower treatment expenses. During surgery decision for preferred pericardium segment is based on visual criteria. Autologous pericardium can be affected by patient's condition and age. Bovine pericardium, also the basic material for aortic valve prostheses, is easy available and carefully pre-examined. In this study, the homogeneity of tissue thickness, elastic modulus, vessel density and ECM components of GA-treated residual pericardia after surgery is compared with bovine pericardia equivalently treated.

Purpose

Aim of the study is the comparison of homogeneity of remaining autologous pericardium after surgical aortic valve replacement with bovine pericardia to evaluate and classify the individual applicability.

Methods

Up to 12 samples of human (n=7) or bovine (n=3) pericardia were analysed. Tissues were treated with 0.6% glutaraldehyde according to surgical protocol. Picrosiriusred- and HE-staining were performed (three edges per separated leaflet). Vessel or collagen content was determined with Zen Blue resp. Fiji software (colour deconvolution plugin, user threshold values). Sample thickness was measured via thickness gauge FD50 before uniaxial tensile testing. Hydroxyproline content was determined and related to dry weight. T-Test or ANOVA were used to test inter-species or intra-individual differences, respectively.

Results

Human pericardia contain with 64.66±3.85% less collagenous fibres compared to bovine pericardia (86.01±1.713%); their vessel density is with 29.46±3.73 mm–2 significantly higher than in bovine samples (12.34±1.636 mm–2). In addition, human pericardia are with 367.7±59.2 μm significantly thinner than bovine (524.4±96.8 μm). Tensile testing (human: 36.00±15.17 MPa; bovine: 41.30±7.767 MPa) also revealed significant differences. With 77.80±11.76 mg/g merely a trend was observed for a lower hydroxyproline content in human samples (bovine 93.16±5.130 mg/g). ANOVA analyses of human pericardia illustrate significant differences for all properties, thus thickness, elastic modulus and hydroxyproline and collagen content between the individual human pericardium samples. In contrast, bovine pericardia showed an intra-individual difference only for the parameter of tissue thickness.

Conclusion

Human and bovine pericardia differ in histological and biomechanical parameters. In contrast to bovine pericardia, individual human pericardia were significantly different in most parameters investigated, leading to the conclusion that autologous materials are critically more heterogeneous than xenogeneic tissues. Vessel density in human pericardium was twofold higher than in bovine pericardia and can result in a higher risk for calcification.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): TU Dresden

Developmental endothelial locus-1 protects from hypertension-induced cardiovascular remodeling via immunomodulation

The causative role of inflammation in hypertension-related cardiovascular diseases is evident and calls for development of specific immunomodulatory therapies. We tested the therapeutic efficacy and mechanisms of action of developmental endothelial locus-1 (DEL-1), an endogenous antiinflammatory factor, in angiotensin II– (ANGII–) and deoxycorticosterone acetate–salt–induced (DOCA-salt–induced) cardiovascular organ damage and hypertension. By using mice with endothelial overexpression of DEL-1 (EC-Del1 mice) and performing preventive and interventional studies by injecting recombinant DEL-1 in mice, we showed that DEL-1 improved endothelial function and abrogated aortic adventitial fibrosis, medial thickening, and loss of elastin. DEL-1 also protected the mice from cardiac concentric hypertrophy and interstitial and perivascular coronary fibrosis and improved left ventricular function and myocardial coronary perfusion. DEL-1 prevented aortic stiffness and abolished the progression of hypertension. Mechanistically, DEL-1 acted by inhibiting α_vβ₃ integrin–dependent activation of pro-MMP2 in mice and in human isolated aorta. Moreover, DEL-1 stabilized α_vβ₃ integrin–dependent CD25⁺FoxP3⁺ Treg numbers and IL-10 levels, which were associated with decreased recruitment of inflammatory cells and reduced production of proinflammatory cytokines in cardiovascular organs. The demonstrated effects and immune-modulating mechanisms of DEL-1 in abrogation of cardiovascular remodeling and progression of hypertension identify DEL-1 as a potential therapeutic factor.

Haemocompatibility testing allows selective adaption of GA-free SULEEI-preparation strategy for bovine pericardium

Background/Introduction

Bovine pericardium is the main natural source for patches or valve substitutes in cardiac surgery, but still, long-term durability is limited. An alternative, glutaraldehyde (GA)-free preparation combining decellularization, riboflavin/UVA crosslinking, and low-energy electron irradiation (SULEEI) procedure was established to avoid this. Protocol optimization is ongoing to further improve the final material. Haemocompatibility in vitro testing with fresh, human whole blood has advantages for material analysis, as it provides essential information on the activation of the complement system and immune cells therefore substantiating and possibly reducing the amount of animal testing.

Purpose

The haemocompatibility testing system was applied to reveal advantageous protocol adaptation of GA-free SULEEI preparation of pericardia.

Methods

Decellularized bovine pericardia were UVA-crosslinked in riboflavin/dextran solution. Protocol SULEEI B adaption includes the addition of trypsin in decellularization buffer and a 10x reduced riboflavin/dextran concentration during prolonged UVA irradiation with reduced intensity. Electron irradiation with 36 kGy was retained. Pericardia were incubated in blood chambers with heparinized human blood (2h, 37°C, GA-fixed/native controls). Inflammation (granulocyte loss and activation [CD11b]), complement activation (C5a) and haemostasis parameters (F1+2, PF4, granulocyte/platelet conjugates, platelet loss) were analyzed via flow cytometry or ELISA. Surface cell adhesion was investigated immunohistologically and via REM-analyses. Nuclear fragments were quantified in HE-stained sections.

Results

Haemostasis parameters F1+2 and PF4 were significantly higher in SULEEI A-pericardium (133±25 nmol/l and 1507±677 U/ml) vs. GA-fixation (2.9±2.9 nmol/l and 320±160 U/ml). Also, granulocyte/platelet conjugates (76.3±18.8%) and platelet loss (40.4±29.7%) were significantly higher after SULEEI A preparation in comparison to GA-fixation (39.3±9.9% and 20.5±6.4%). SULEEI B treated pericardia did not differ significantly. C5a complement activation was significantly lower in SULEEI A samples but comparable in SULEEI B to GA-fixed material. This is in contrast to a higher rate of nuclear fragments in SULEEI A tissue HE stained sections. Granulocyte activation of SULEEI pericardium (A: 89.8±29.7%; B: 106.2±18.8%) was significantly higher compared to native (46.1±22.6%) and for SULEEI B higher than in GA-fixed samples (67.2±9%). Granulocyte loss was comparable to GA-fixed pericardium after SULEEI B protocol. REM-analyses and histological evaluation visualized a dense blood cell and fibrin covering particular of SULEEI A-pericardium.

Conclusions

Haemocompatibility testing reveals advantageous properties of SULEEI B-pericardium. The impact of treatment substances such as dextran on high inflammatory response and dense surface covering in SULEEI A protocol is focus in ongoing experiments.

Funding Acknowledgement

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): EU/EFRE

Diminished PLK2 Induces Cardiac Fibrosis and Promotes Atrial Fibrillation

[Figure: see text].

Establishment of a resazurin-based aortic valve tissue viability assay for dynamic culture in a microphysiological system

BACKGROUND/AIM

Tissue pathogenesis of aortic valve (AV) stenosis is research focus in cardiac surgery. Model limitations of conventional 2D culture of human or porcine valvular interstitial/endothelial cells (VIC/VECs) isolated from aortic valve tissues but also limited ability of (small) animal models to reflect human (patho)physiological situation in AV position raise the need to establish an in vitro setup using AV tissues. Resulting aim is to approximate (patho)physiological conditions in a dynamic pulsatile Microphysiological System (MPS) to culture human and porcine AV tissue with preservation of tissue viability but also defined ECM composition.

MATERIALS/METHODS

A tissue incubation chamber (TIC) was designed to implement human or porcine tissues (3×5 mm2) in a dynamic pulsatile culture in conventional cell culture ambience in a MPS. Cell viability assays based on lactate dehydrogenase (LDH)-release or resazurin-conversion were tested for applicability in the system and applied for a culture period of 14 days with interval evaluation of tissue viability on every other day. Resazurin-assay setup was compared in static vs. dynamic culture using varying substance saturation settings (50-300μM), incubation times and tissue masses and was consequently adapted.

RESULTS

Sterile dynamic culture of human and porcine AV tissue segments was established at a pulsatile flow rate range of 0.9-13.4μl/s. Implementation of tissues was realized by stitching the material in a thermoplastic polyurethane (TPU)-ring and insertion in the TIC-MPS-system. Culture volume of 2 ml caused LDH dilution not detectable in standard membrane integrity assay setup. Therefore, detection of resazurin-conversion of viable tissue was investigated. Optimal incubation time for viability conversion was determined at two hours at a saturated concentration of 300μM resazurin. Measurement in static conditions was shown to offer comparable results as dynamic condition but allowing optimal handling and TIC sterilization protocols for long term culture. Preliminary results revealed favourable porcine AV tissue viability over a 14 day period confirmed via resazurin-assay comparing statically cultured tissue counterparts.

CONCLUSIONS

Human and porcine AV tissue can be dynamically cultured in a TIC-MPS with monitoring of tissue viability using an adapted resazurin-assay setup. Preliminary results reveal advantageous viability of porcine AV tissues after dynamic TIC-MPS culture compared to static control.

Characterization of thoracal fat depots - expression of adipokines and remodeling factors and impact of adipocyte conditioned media in fibroblast scratch assays

Adipose tissue is not only a connective tissue but also an endocrine organ secreting adipokines like Leptin and Adiponectin, lipokines such as palmitoileic acid and extracellular vesicles. These factors and the expression of matrix remodeling enzymes impact surrounding tissues via paracrine effects. The expression of selected secretion factors and the effect of adipocyte conditioned media from four thoracal adipose tissue origins - subcutaneous, perivascular, pericardial and epicardial adipose tissues - in a fibroblast proliferation/wound healing scratch assay model were investigated. Results were compared directly and according to the type 2 diabetic mellitus (T2DM) status of the patients the tissues are originated from. Adipocyte conditioned media from non-diabetic patients resulted in a significant higher scratch closure rate compared to the media with T2DM background. Linoleic acid incubation in scratch assay resulted in a reduced scratch closure rate. Leptin, Adiponectin and Visfatin/Nampt expression and MMP2, MMP9 and FSTL1 mRNA levels did not vary according to T2DM subgroups directly, leading to the assumption that these factors are not causal for scratch assay effects observed. In contrast significant mRNA expression differences were monitored between the thoracal tissue origins implying variations in the local effects of the different adipose tissue depots.

Readmission to the intensive care unit after cardiac surgery: a single-center experience with 7105 patients

AIM

Identification of patients at high risk for readmission to the Intensive Care Unit (ICU) after cardiac surgery is paramount. We evaluated the clinical characteristics of readmitted patients and identified perioperative prognostic variables for ICU readmission.

METHODS

A total of 7105 patients who underwent cardiac surgery between 2007 and 2010 and discharged after a primary stay in the ICU were reviewed retrospectively. Of these, 7.8% (554) patients were readmitted. The reasons for readmission and postoperative course were analyzed. Perioperative risk factors for readmission were determined by multivariate regression analysis.

RESULTS

Mortality of patients after readmission was 13.6% compared with 0.2% without recidivism (P<0.0001). Mean length of stay in hospital of patients requiring readmission was 24.9 ± 19.1 days and significantly longer compared to all other patients 12.3±8.4 days (P<0.0001). The main reasons for readmission were respiratory failure (39.0%) and cardiovascular instability (26.2%). Complex cardiac surgery, aortic surgery and extended stay in the ICU were the most powerful variables to predict ICU readmission.

CONCLUSION

ICU readmission was related to complex surgery and associated with impaired outcome. Respiratory complications were the most common reasons for readmission. Predictive renal and pulmonary risk factors indicate the need of preoperative preconditioning and patient selection.

[Transapical aortic valve implantation--indications, risks and limitations]

Calcified aortic stenosis is the predominant valve disease in the western world. Currently, surgical aortic valve replacement is the gold standard procedure for symptomatic severe aortic stenosis that can be performed with low morbidity and mortality. The prevalence of aortic stenosis increases with age, and the incidence of several comorbidities also unavoidably elevates the risk of surgical treatment. Therefore, the most adequate and gentle treatment is needed especially for this population. Since the first transcatheter aortic valve implantation (TAVI) was performed in 2002, the main implanting routes are the transfemoral, retrograde access through the common femoral artery, and the antegrade, transapical approach via anterolateral minithoracotomy. Meanwhile, TAVI has become an alternative treatment for patients who are not suitable candidates for surgical therapy in some centers.The initial clinical results are promising and have confirmed the feasibility of this technique. Due to the restricted long-term data, conventional aortic valve replacement still remains the standard for the treatment of aortic stenosis. Selection of the suitable therapy approach (surgical replacement, transfemoral or transapical aortic valve implantation) must consider each patient's specific risk profile and individual indication. Prospective, randomized trials will be necessary to assess the individual survival benefit of TAVI for various risk populations and to extend the indication.

Perforation of the Ascending Aorta: A Late Complication of Superior Vena Cava Stenting

Intravascular stenting of the superior vena cava (SVC) is an established therapy in patients with SVC syndrome. Late complications include re-occlusion, stent infection, migration, and perforation. Affection of the greater thoracic vessels is rare and life-threatening when it occurs. We present a case of ascending aorta laceration as a late complication of SVC stenting. Surgical therapy included excision of the aortic lesion and pericardial patch repair. This case illustrates successful management of a complication after palliative stenting of the SVC.

Coronary reoperation with and without cardiopulmonary bypass

Redo coronary artery bypass grafting (CABG) is still associated with increased morbidity and mortality compared to primary operation. Myocardial protection is one of the key issues in redo on pump CABG and is still a matter of debate. Off pump redo CABG seems to be an attractive alternative as native coronary blood flow remains and cross clamping of the aorta is avoided. The aim of this retrospective study was to compare the outcome of redo CABG with and without CPB. From 1/1998 to 5/2004 redo CABG was performed in 195 patients (pts): 162 male (83.1%) and 33 female (16.9%) pts, age 66 +/- 9 years. In 160 pts, CPB with isolated antegrade myocardial protection was used for redo CABG. Off pump redo CABG was performed in 35 pts (30 male (85.7%) and 5 female (14.3%), age 67 +/- 8 years). Perioperative overall mortality rate was 3.6% (n = 7) and comparable in both groups (on pump 3.8% versus off pump 2.9%; p = 0.90), as well as perioperative myocardial infarction, intraaortic balloon pump implantation rate and secondary morbidity. Complete revascularization was achieved in 139 pts (86.9%) after on pump CABG and in 17 pts (48.6%) of the off pump group (p < 0.01). The average number of grafts was significantly higher in the on pump group (2.8 +/- 0.78 versus 1.6 +/- 0.6; p = 0.04).Furthermore, 20 pts (12.5%) in the on pump group died during follow-up (50 +/- 16 months). Five pts (25.0%) died due to cardiac reasons. In the off pump group 3 pts (8.6%) died during follow-up (44 +/- 13 months), noncardiac related. Overall survival was 83.8% in the on pump group and 88.6% in the off pump group (p = 0.92). On pump redo CABG and off pump redo CABG can be safely performed with low mortality and morbidity. Off pump redo CABG might be limited due to incomplete revascularization.

Influence of extra corporeal circulation on myocardial oxygen tension: results of an animal model

BACKGROUND

Experimental data have shown the potential risk of cellular damage of the myocardium during extra corporeal circulation (ECC). The influence of ECC on myocardial oxygen tension however remained unclear. Therefore, the influence of ECC on the oxygen tension in a beating heart was investigated.

METHODS

In a pig animal model flexible pO2 microcatheters were positioned in the midmyocardium of the left ventricle and the skeletal muscle and tissue oxygen tension during ECC were monitored and compared with data of a control group without ECC.

RESULTS

ECC and unload of the heart caused a significantly higher increase of myocardial pO2 than in a non-ECC control group.

CONCLUSION

Our findings show the beneficial effect of ECC on myocardial pO2. This may support the use of ECC in coronary artery bypass grafting because the potential myocardial injury due to ECC is not related to myocardial ischemia. On the contrary, myocardial pO2 was even increased during extracorporeal circulation in this study.

Lactatdehydrogenase (LDH) prior and post implantation of ATS® heart valves

Establishing guidelines towards an assessment of prostheses dysfunction using LDH as a marker is difficult as shown by [M. Suedkamp, A.J. Lercher, F. Mueller-Riemenschneider, K. LaRosee, P. Tossios, U. Mehlhorn, Hemolysis parameters of St Jude Medical hemodynamic valves in aortic position, Int. J. Cardiol (95) (2004) 89-93]. In response to their work we would like to add our data concerning ATS valves (AP) and say a word of caution in interpreting an increase of LDH values.

Coronary surgery in dialysis-dependent patients with end stage renal failure

The number of patients with dialysis-dependent end stage renal failure (ESRF) and coronary heart disease (CAD) has increased in recent years. Coronary artery bypass grafting (CABG) has become the standard treatment for CAD in this patient group, but is still considered as a risk procedure due to increased mortality and morbidity. In a retrospective study we analyzed our clinical results of isolated CABG in 40 dialysis-dependent patients with ESRF (5 female and 35 male, mean age 65+/-8.4 years) and the use of extracorporeal circulation. The perioperative control group comprised 51 patients (10 female and 41 male, mean age 67+/-7.3 years) with normal renal function and isolated CABG. Demographic and preoperative data were comparable in both groups. Hospital mortality was 2.5% in patients with ESRF and 0% in patients with normal renal function. Morbidity was comparable in both groups. The mean number of grafts was 3.1+/-0.9 in the dialysis group and 2.9+/-0.8 in the control group. In the follow-up of the dialysis group (34+/-23 months) 8 patients died. CABG in patients with dialysis-dependent ESRF can be performed with good clinical results and morbidity comparable to patients with normal renal function.

Mortality after cardiac surgery with or without microwave ablation in patients with permanent atrial fibrillation

BACKGROUND AND AIM OF THE STUDY

The surgical treatment of atrial fibrillation (AF) by Cox and other ablation methods shows a 50-90% conversion rate to sinus rhythm. However, to date no study has addressed the influence of ablation on the mortality rate.

METHODS

The perioperative and postoperative mortalities of 210 consecutive patients with permanent AF was investigated for up to two years after cardiac surgery with (n = 111) or without (n = 99) endocardial microwave ablation within the framework of a prospective register study. All patients were followed up.

RESULTS

In the ablation group, one patient (0.9%) died perioperatively, seven died during the first year of follow up (6.3%), and nine in the second year of follow up (8.1%). In the control group, five patients died perioperatively (5.1%), 12 died in the first year of follow up (12.1%), and 22 in the second year of follow up (22.2%). During the two-year follow up period, significantly more patients died in the control group than in the ablation group (Log-Rank test: p = 0.0051).

CONCLUSION

The results of this register study showed that among patients with permanent AF who underwent cardiac surgery with ablation, mortality was significantly lower than in those who underwent comparable surgery but without ablation. The marked difference in mortality was essentially based on the typical clinical consequences of AF (e.g. thromboembolic complications, cardiac arrhythmias and bleeding complications due to anticoagulation therapy), which occurred less often in the ablation group.

Influence of ventricular pacing on myocardial oxygen tension

INTRODUCTION

The influence of heart rate on cardiac output, oxygen consumption, and myocardial activity has been widely investigated. However, the influence of heart rate on myocardial oxygen tension (pO2) remains unclear. Since the introduction of flexible pO2 micro catheters to measure partial oxygen tension in a working muscle, it is possible to investigate the influence of heart rate on myocardial oxygen tension.

METHODS

Intraoperatively, a flexible pO2 micro catheter was positioned in the mid-myocardium of 8 male farm pigs. The heart rate was varied via an external pacer from base rate up to fibrillation and the corresponding myocardial pO2 was measured.

RESULTS

Within 2 min, the myocardial pO2 adjusted to a change in heart rate. In this animal model, an optimal myocardial pO2 was observed at 109 bpm. A further increase in heart rate led to a decrease in myocardial pO2. When the heart rate was reaching the level of a fibrillation, pO2 dropped to zero.

CONCLUSION

In young healthy pigs--with a normal blood vessel regulation and the pharmacologic and experimental conditions used in this study--a significant relation between myocardial pO2 and heart rate was observed. Myocardial oxygen tension increased during cardiac pacing until a heart rate of 109 bpm. Thereafter a decline of pO2 occurred. Each change in heart rate resulted in a corresponding change of pO2 within roughly 2 min.

[Surgical therapy of infective endocarditis]

Therapy of infective endocarditis (IE) remains a particular challenge due to a relative high morbidity and mortality. Cardiac surgery is established as a cornerstone in therapy for native valve endocarditis (NVE) as well as for prosthetic valve endocarditis (PVE) and is required in 30% of patients with active IE. The basic aim of surgery in IE is the radical debridement of infected tissue and reconstruction of valve function either by reconstructive valve surgery or valve replacement. Indication for surgery depends on several clinical variables, the main indication remains heart failure due to severe heart valve defects or prosthetic valve dysfunction. Surgical therapy of NVE can be performed with good clinical results in the early and late follow-up. Surgical therapy of PVE is still associated with quite high mortality up to 80% in some risk groups. This indicates the particular importance of focus evaluation and antibiotic prophylaxis after primary surgery for infective endocarditis.

Chirurgische Therapie nach traumatischen interventionellen Koronarl�sionen

Coronary perforation and entrapment of catheter materials are rare, but life-threatening complications, which often require emergency cardiosurgical treatment. Surgical options include tamponade drainage, coronary artery bypass grafting, perforation suturing, and removal of catheter materials. Surgical strategies are not standardized but mainly depend on the surgical anatomy. This is in particular true for the removal of the catheter remnants (stent, guidewire). Keeping this in mind, these patients can be treated with good clinical results.

Influence of radiographic contrast media on myocardial tissue oxygen tension: NaCl-controlled, randomised, comparative study of iohexol versus iopromide in an animal model

It was tested whether a bolus injection of 10 ml radiographic contrast medium (iopromide vs. iohexol), compared to a 10 ml NaCl bolus and administered into the left anterior descending artery (LAD) of farm pigs, influenced the tissue pO2 in the territory of this artery. The radiographic contrast media and the NaCl bolus were given in randomised order. The mean pO2 LAD fell from initially 40.3+/-10.9 mmHg to a minimal value of 22.5+/-8.9 mmHg 241+/-44 sec after injecting the iopromide bolus, with this result representing a mean decrease of 44.2% (p=0.0003). The initial pO2 (baseline) was reached again after approximately 10 minutes. The mean pO2 LAD fell from the initial value of 34.5+/-14.6 mmHg to a minimal value of 29.4+/-13.9 mmHg 171.7+/-11.9 sec after injection of the iohexol bolus, with this result representing a mean decrease of 14.8% (p=0.0003). The baseline pO2 was reached again after approx. 5 minutes. The drop in the pO2 after iopromide administration was significantly larger than that after iohexol (p=0.0001), and also the time after which the baseline pO2 is reached again was considerably shorter for iohexol (p=0.001). The two radiographic contrast media did not influence the tissue pO2 in either the territory of the right coronary artery or in skeletal muscle. Injection of a NaCl bolus into the LAD influenced neither the tissue pO2 of the territory of the LAD nor that of the RCA or of the skeletal muscle. The tissue temperature, heart rate and the systolic and diastolic blood pressure were not affected during the three injections. Injection of radiographic contrast media into a coronary artery can lead to a distinct, local microcirculatory impairment in the myocardial territory supplied by this artery. In this case, the extent of the microcirculation impairment seems to depend not only on the viscosity of the contrast media but rather also on its chemotoxicity.

[Space occupying lesion of unknown origin in the pulmonary trunk: targeted differential diagnosis and surgical therapy in a patient with B symptoms and thoracic pain]

Leiomyosarcomas are only rarely found in routine cardiac surgery. For the patient they hold, however, a very high-risk potential as only an early diagnosis, and immediate surgical therapy leads to long-term survival. Awareness, timely diagnosis, and immediate radical surgical therapy is imperative. This report describes the case of a 21-year old male with a strong suspicion of leiomyosarcoma of the pulmonary artery. Due to his clinical symptoms, the patient was transferred to operation immediately after completion of all diagnostic measurements. Postoperatively the diagnosis of a leiomyosarcoma proved to be false; instead a rare fibro-histologic tumor was found. Even in the case of a suspected leiomyosarcoma, rapid and radical surgical therapy is imperative due to the poor prognosis of leiomyosarcoma.

Closed chest coronary artery bypass on the beating heart

Minimally invasive surgical procedures have become a part of routine cardiac surgery. The surgical techniques have been developed for the treatment of coronary artery disease in order to minimize surgical trauma. With the introduction of a 3-D-based totally endoscopically functioning system into minimally invasive cardiac (MIC) surgery, further reduction of skin incisions became possible and enhanced MIC techniques could be improved. Due to the 6 degrees freedom of motion allowed by wrist-enhanced instruments and a newly developed endoscopic stabilizer, totally endoscopic coronary artery bypass procedures on a beating heart became feasible. We present here our initial series of totally endoscopic "off-pump" coronary artery bypass grafting in patients suffering from coronary artery single vessel disease. In all patients, the procedure was successfully performed via four 1 cm chest incisions as closed-chest procedures.

Technique of closed chest coronary artery surgery on the beating heart

OBJECTIVE

The application of an endoscopic stabilizer (Intuitive Surgical, Mountain View, CA, USA) enables closed chest off-pump coronary artery bypass via a four-point stab incision avoiding sternotomy and minithoracotomy.

METHODS

Between May 1999 and January 2001 we operated upon a total of 37 patients (five female, 32 male, median age 62+/-9 years) suffering from coronary artery disease using totally endoscopic coronary artery bypass (TECAB), whereas an initial series of eight TECAB patients was operated upon using an endovascular bypass system (Heartport). The da Vinci surgical system was used in order to perform left internal mammary artery (LIMA) or right internal mammary artery (RIMA) harvesting and anastomoses on a beating heart in 29 patients (four female, 25 male, median age 64+/-9.8 years). Altogether 26 patients suffering from single-vessel coronary artery disease (SVCAD) were revascularized applying LIMA to the left anterior descending artery (LAD) and three patients with two diseased coronary vessels received bilateral internal mammary artery grafting (BIMA), respectively.

RESULTS

In this series we had a 100% survival rate. Conversion rate to a median sternotomy was 3.4%. Patients were operated upon via four 1-cm chest incisions using the da Vinci robot for LIMA or BIMA harvesting and for performance of anastomoses on the beating heart. In the overall series of 56 patients intended to be treated by TECAB, 19 (33.9%) were converted to a minimally invasive direct coronary artery bypass procedure.

CONCLUSION

This new robotic-enhanced surgical technique promotes an optimistic way of thinking about the further development of this procedure and its application in patients suffering from single-vessel CAD.

Development of robotic enhanced endoscopic surgery for the treatment of coronary artery disease

BACKGROUND

The introduction of robotic enhanced surgery demanded stepwise development of performed procedures on the basis of growing experience of the operating team.

METHODS AND RESULTS

Between May 1999 and January 2001, this new wrist-enhanced instrumentation was used in 201 patients (156 men and 45 women, median age 64+/-10.5 years, left ventricular ejection fraction 68+/-12.4%). During the development of robotic enhanced CABG, the patients were divided into 3 groups. Group A (n=156) consisted of patients in whom the robotic system was used to harvesting the left or right internal mammary artery, or both, whereas the anastomoses were performed directly through a small chest incision. In group B (n=37), the harvest of the internal mammary arteries and the coronary anastomoses were performed totally endoscopically. In a third early group C, patient (n=8) were treated with robotic enhanced CABG via a median sternotomy already preoperatively planned, whereas gradual step-by-step application of robotic instrumentation and its feasibility were assessed. The survival rate was 99.4%. One patient (0.6%) died due to pneumonia on postoperative day 16. Conversion rate to median sternotomy was 5%. The left and right internal mammary artery conduits could be successfully harvested in 98% and 100%, respectively. The time of dissection of the left internal mammary artery could be significantly reduced alone by increasing experience. All patients were discharged from the hospital after a mean of 7 days. In 9 patients (4.5%), bleeding required reexploration.

CONCLUSIONS

The introduction of this new surgical tool enables the development of new endoscopic procedures. Our results gained during the development of robotic enhanced CABG motivate us to establish a set standard for the totally endoscopic treatment of patients with 1-vessel coronary artery disease.

Robotic-enhanced Dresden technique for minimally invasive bilateral internal mammary artery grafting

BACKGROUND

The introduction of robotic-enhanced endoscopic instrumentation systems allows the surgeon to perform arterial revascularization for multivessel coronary artery disease without sternotomy.

METHODS

From April 1999, 27 patients (6 female, 21 male, median age 63 +/- 8.2 years) suffering from multivessel coronary artery disease were treated surgically using arterial revascularization by means of bilateral internal mammary artery (BIMA) grafting. Both arteries were harvested totally endoscopically using the da Vinci robotic surgical system (Intuitive Surgical, Mountain View, CA). These vessels were anastomosed using the "Dresden Technique" via a left minithoracotomy in the second intercostal space.

RESULTS

All patients survived the operation. The mean duration of surgery was 240 +/- 79.4 minutes. Bilateral internal mammary artery harvesting time was 88.5 +/- 15.9 minutes, and cross-clamp time was 38 +/- 10.9 minutes. An average of 2.07 anastomoses were performed per operation. Postoperatively, the patients remained in ICU for 20 +/- 2.4 hours. One patient needed reexploration due to bleeding.

CONCLUSIONS

Bilateral internal mammary artery harvesting can be achieved safely with the use of wrist-enhanced instrumentation. The robotic surgical system introduces into surgical practice a new type of treatment of coronary artery disease, helping to perform arterial revascularization with a distinctly reduced surgical trauma.