Intractable ventricular tachycardia and bridging to heart transplantation with a non-pulsatile flow assist device in a patient with isolated left-ventricular non-compaction.

Intractable ventricular tachycardia was investigated in a 51-year-old man with isolated left ventricular non-compaction during implantation of an automated internal cardioverter-defibrillator. Favorable bridging to cardiac transplantation was achieved with the DeBakey left ventricular assist device (LVAD).

Continuous blood pressure monitoring utilizing a CMOS tactile sensor.

A novel tactile device based on a monolithically integrated sensor chip is presented for external blood pressure measurement. It uses a tonometric principle, thus allowing for continuous monitoring of the blood pressure without the need for an invasive catheter. On the chip, the deflection of membranes in an array is sensed capacitively and read out using a SigmaDelta-modulator. The membrane array and the modulator are fabricated on a single chip using an industrial CMOS (complementary metal oxide semiconductor) technology combined with post-process micromachining to achieve small and portable devices with low power consumption. The tested device is operated at a conversion rate of 1 kilosamples per second and is pressure biased to a 2000 hPa (1500 mmHg) reference point. The power consumption of the sensor chip is 11.5 mW with signal-to-noise ratio better than 72 dB. During testing a pressure resolution of approximately 8 hPa (6 mmHg) for one digit at the output of the SigmaDelta-modulator is achieved over the range of interest continuous blood pressure monitoring using this CMOS-based tactile device is successfully demonstrated. The characteristic features of a blood pressure waveform are clearly recognizable from the acquired data.

Experiences in robotically enhanced IMA-preparation as initial step towards totally endoscopic coronary artery bypass grafting.

AIM: To evaluate the feasibility of robotically enhanced preparation of internal mammary arteries (IMA). METHOD: Via three trocars in left thoracic wall the left, right or both IMA were skeletonized under CO(2) insufflation and single lung ventilation using electrocautery. RESULTS: In 12 months, 26 LIMA, five BIMA and one RIMA were dissected. In five patients, the procedure had to be determined (IMA injury (two), respiratory insufficiency (two), and heart penetration (one)). Mean intrathoracic pressure was 9.7+/-1.5 mmHg. Mean time for LIMA and RIMA dissection was 66.7+/-21.1 and 99.2+/-8.7 min, respectively. In 10 patients, pericardium was incised and course of LAD assessed. However, in two patients, this coronary did not correlate with LAD. Time for instrument change depended on type of tool (cautery blade: 24.9+/-13.1 s, clip applier 72.8+/-28.4 s). CONCLUSION: Robotic dissection of IMA is reasonable. However, life-threatening complications can barely be managed due to inadequate tools and excessive time for instrument change. Incorrect determination of coronaries can result in misplaced anastomoses.

Left ventricular assist device as bridge to heart transplantation--lessons learned with the MicroMed DeBakey axial blood flow pump.

OBJECTIVE: The MicroMed DeBakey left ventricular assist device (LVAD) axial blood flow pump was used as bridge to heart transplantation (HTx) in patients with terminal heart failure. The aim was to evaluate this novel mechanical circulatory support system in regard to overall outcome. METHODS: Prospective study in 15 HTx candidates (mean age 40+/-7 years) with terminal heart failure and maximal medical treatment due to ischemic cardiomyopathy (CMP, n=5), dilated CMP (n=3), restrictive CMP (n=2), unclassified CMP (n=1), metabolic CMP (n=1), valvular CMP (n=1) and congenital CMP (n=2). All patients were implanted with a MicroMed DeBakey LVAD. A rescue procedure was necessary in eight critical patients, while seven underwent elective LVAD implantation. Procedures were performed via median sternotomy, in normotherm femoro-femoral CPB (mean duration 59+/-1 min). Oral Marcoumar (INR 2.0-3.0) and Aspirin (100 mg daily) were started as soon as possible. Patients were discharged into a specialized rehabilitation clinic from which it was possible to release them home after a few weeks. RESULTS: Successful implantation and discharge from ICU (mean stay 10+/-7 days) was possible in 11 patients. Seven were transplanted (mean support 50.7 days) and one is awaiting HTx (support >310 days) in the comfort of his home (NYHA I). Survival was 100% among the transplanted patients. Of the seven elective implants, five, and of the eight rescue procedures three patients underwent successful HTx. Four patients died early, while three patients died late on pump support due to intracranial hemorrhage (n=2, 73 and 76 days) and chest infection (n=1, 124 days). All survivors were discharged from hospital, with significant decrease in NYHA class (mean 3.8-2.4 (n=11)). Treadmill testing showed increased exercise tolerance, from 35 to 71W (n=4). Plasma BNP values (mean 950-162 ng/l (n=4)) and pulmonary resistance (mean 316-194.5 dyne s/cm(5) (n=3)) decreased significantly during LVAD support. CONCLUSIONS: The MicroMed DeBakey LVAD is simple to implant; outpatient treatment is safe and efficient. Patients' condition and pulmonary resistances normalize within 6 weeks, making previously considered inoperable patients amenable for HTx. HTx can be performed in low-risk situation, allowing better donor-recipient matching and improving overall outcome.

The relevance of large strains in functional tissue engineering of heart valves.

BACKGROUND: Exposing the developing tissue to flow and pressure in a bioreactor has been shown to enhance tissue formation in tissue-engineered heart valves. Animal studies showed excellent functionality in these valves in the pulmonary position. However, they lack the mechanical strength for implantation in the high-pressure aortic position. Improving the in vitro conditioning protocol is an important step towards the use of these valves as aortic heart valve replacements. In this study, the relevance of large strains to improve the mechanical conditioning protocol was investigated. METHODS: Using a newly developed device, engineered heart valve tissue was exposed to increasing cyclic strain in vitro. Tissue formation and mechanical properties were analyzed and compared to unstrained controls. RESULTS: Straining resulted in more pronounced and organized tissue formation with superior mechanical properties over unstrained controls. Overall tissue properties improved with increasing strain levels. CONCLUSIONS: The results demonstrate the significance of large strains in promoting tissue formation. This study may provide a methodological basis for tissue engineering of heart valves appropriate for systemic pressure applications.

Advanced training model for beating heart coronary artery surgery: the Zurich heart-trainer.

OBJECTIVE: Coronary artery surgery with beating heart technique is gaining increasing popularity. However, it is a challenging technique even for well-trained cardiac surgeons. Thus, a training model for beating heart surgery was developed to increase safety and accuracy of this procedure. METHODS: The model consists of differentially hardened polyurethane resembling mechanical properties of the human heart. The covering used in this model is a 1:1 replica of the human thoracic wall with optionally embedded skeletal structures. Sternotomy, lateral thoracotomy or trocar placement is possible to access the lungs, the pericardium and the heart with adjacent vessels. Disposable artificial coronaries variable in size, wall quality or wall thickness are embedded in the synthetic myocardium. Two-layer vessels, which can simulate dissection, are available. Bypass conduits utilize the same material. Coronaries/bypasses as well as part of the ascending aorta are water-tight and can be rinsed with saline. Lungs can be inflated. A purpose-built pump induces heart movement with adjustable or randomized stroke volume, heart rate and arrhythmia induction. RESULTS: The model was tested in a recent 'Wet-Lab' course attended by 30 surgeons. All conventional instruments and stabilizers with standard techniques can be used. Training with beating or non-beating heart was possible. Time needed for an anastomosis was similar to clinical experience. Each artificial tissue showed its individual nature-like qualities. Various degrees of difficulty can be selected, according to stroke volume, heart rate, arrhythmia, vessel size and vessel quality. The model can be quickly and easily set up and is fully reusable. CONCLUSIONS: The similarity to human tissue and the easy set-up make this completely artificial model an ideal teaching tool to increase the confidence of cardiac surgeons dealing with beating heart and minimally invasive surgery.

Endoscopic saphenous vein harvesting for CABG -- a randomized, prospective trial.

BACKGROUND: The saphenous vein is an established conduit for coronary revascularization. Disadvantages of traditional harvest technique are significant pain and morbidity. We compared the endoscopic harvest technique with the traditional method. METHOD: 140 coronary artery bypass graft (CABG) patients were randomized into 2 groups: endoscopic vein harvesting (EVH; n = 80) and traditional open vein harvesting (OVH; n = 60). Analysis included preoperative risk factors for wound complication, harvesting time, graft injury, and intraoperative and postoperative complications. Patient follow-up lasted 3 months. RESULTS: The preoperative risk profiles of the groups were comparable. In the EVH group, 5 patients (7.1 %) had to be switched to the open technique. EVH time was 45 +/- 6.2 min vs. 31.1 +/- 6.5 min. Two patients (2.5 %) had to be revised because of bleeding complication vs. 6 (10 %) in the OVH group. No local infections or wound complications were observed in the EVH group vs. 11 (18 %) cases in the OVH group. Two OVH cases (3.6 %) were readmitted for wound debridement. All EVH patients reported less pain and were completely satisfied by the cosmetic results. CONCLUSION: EVH is a safe and efficient technique for CABG. Morbidity was significantly lower, with reduced pain and better cosmetic results. EVH time was significantly longer compared to the traditional harvesting technique.

Total robotic-enhanced pericardiectomy for effusive pericarditis.

With the DaVinci Robot only recently in clinical use, limitations of video-assisted thoracoscopy could disappear due to Endo-Wrist features, tremor cancellation and three-dimensional view. This report describes the total endoscopic pericardiectomy successfully achieved with robotic assistance in a 50-year-old man suffering from effusive pericarditis.

Tissue engineering: complete autologous valve conduit--a new moulding technique.

OBJECTIVE: The use of fibrin gel, which can be produced from patients' blood, was investigated as an autologous, biodegradable scaffold. A new moulding technique was developed to create a complete aortic root. METHODS: A new moulding technique was generated for the creation of complete valve conduit. On the basis of biomechanical valve design studies, a tricuspid "ventricular" and "aortic" stamp were developed. A silicone-coated aluminum cylinder was used to circumferentially limit the mould. The cell/gel suspension was filled into the mould and polymerization was started. RESULTS: The creation of complex structures such as complete valve conduits is possible with the moulding technique described. With a layer thickness of up to 2 mm, histological investigations showed excellent tissue development with viable fibroblasts surrounded by collagen bundles. CONCLUSION: Fibrin gel unifies many properties of an ideal scaffold: The formation of complex structures is possible, the degradation and polymerization is controllable and the formation of the extracellular matrix is excellent.

Preoperative administration of steroids: influence on adhesion molecules and cytokines after cardiopulmonary bypass.

BACKGROUND: Cardiopulmonary bypass (CPB) is associated with tissue damage mediated by adhesion molecules and cytokines. Prebypass steroid administration may modulate the inflammatory response, resulting in improved postoperative recovery. METHODS: Fifty patients undergoing elective coronary operations under normothermic CPB were randomized into two groups: group A (n = 24) received intravenous methylprednisolone (10 mg/kg) 4 hours preoperatively, and group B (n = 26) served as controls. Cytokines (tumor necrosis factor-alpha [TNF-alpha], interleukin-2R [IL-2R], IL-6, IL-8), soluble adhesion molecules (sE-selectin, sICAM-1), C-reactive protein, and leukocytes were measured before steroid application, then 24 and 48 hours, and 6 days postoperatively. Adhesion molecules were measured by enzyme-linked immunosorbent assay, cytokines by chemiluminescent immunoassay. Postoperatively, hemodynamic measurements, inotropic agent requirements, blood loss, duration of mechanical ventilation, and intensive care unit stay were compared. RESULTS: Aortic cross-clamp and CPB time was similar in both groups. Prednisolone administration reduced postoperative levels of IL-6 (611 versus 92.7 pg/mL; p = 0.003), TNF-alpha (24.4 versus 11.0 pg/L, p = 0.02), and E-selectin (327 versus 107 ng/mL, p = 0.02). Postoperative recovery did not differ between groups. CONCLUSIONS: Preoperative administration of methylprednisolone blunted the increase of IL-6, TNF-alpha, and E-selectin levels after CPB but had no measurable effect on postoperative recovery.

Optimal cell source for cardiovascular tissue engineering: venous vs. aortic human myofibroblasts.

Arterial vascular cells have been successfully utilized for tissue engineering in human cardiovascular structures, such as heart valves. The present study evaluates saphenous vein-derived myofibroblasts as an alternative, easy-to-access cell source for human cardiovascular tissue engineering. Biodegradable polyurethane scaffolds were seeded with human vascular myofibroblasts. Group A consisted of scaffolds seeded with cells from ascending aortic tissue; in group B, saphenous vein-derived cells were used. Analysis included histology, electron microscopy, mechanical testing, and biochemical assays for cell proliferation (DNA) and extracellular matrix (collagen). DNA content was comparable in both groups. Collagen and stress at maximum load was significantly higher in group B. Morphology showed viable, layered cellular tissue in all samples, with collagen fibrils most pronounced in group B. In conclusion, saphenous vein myofibroblasts cultured on biodegradable scaffolds showed excellent in vitro tissue generation. Collagen formation and mechanical properties were superior to aortic tissue derived constructs. Therefore, the easy-to-access vein cells represent a promising alternative cell source for cardiovascular tissue engineering.

Genetic predisposition in patients undergoing cardiopulmonary bypass surgery is associated with an increase of inflammatory cytokines.

OBJECTIVE: Cardiopulmonary bypass (CPB) surgery induces a transient rise in pro-inflammatory cytokines typically released by activated monocytes. The E4 variant of apolipoprotein E is a recognized risk factor for atherosclerosis. It has recently been shown that apolipoprotein E affects monocyte functions in vitro and leads to higher levels of median lipoprotein (a) in humans. The aim of the study is to investigate if the E4 genetic variant of apolipoprotein E affects cytokine release after CPB surgery. METHODS: 22 patients were operated on with standard coronary artery bypass grafting. Concentrations of interleukin 8 (IL-8) and tumor necrosis factor (TNF-alpha) were measured by automated Immulite immunoassay at regular intervals within 48 h after surgery. Total apparent cytokine outputs were calculated as area under the curve. Results are expressed as mean+/-standard deviation and compared by unpaired t-test. RESULTS: In the presented patient population 6 (27%) carried the E4 allele. Sixteen (63%) showed no E4 allele. Mean cross clamp time (CCT) was 56.2+/-13.5 min versus 55.7+/-12.1 min and CPB time was 91.8+/-17.5 versus 93.5+/-15.7 min. No statistical difference between E4-carriers and E4 non-carriers regarding CCT and CPB was observed. The total amount of IL-8 and TNF-alpha was higher in patients carrying the E4 genetic variant of apolipoprotein E in comparison to E4 non-carriers (P<0.08, P<0.039). CONCLUSION: The presence of the E4 allele is associated with increased release of IL-8 and TNF-alpha after CBP surgery. The preoperative determination of E4 in patients undergoing cardiac surgery may lead to additional perioperative measures for the treatment of an increased systemic inflammatory response.

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 formation.

Surgical management of retro-aortic left renal vein in combined abdominal aortic and coronary surgery.

Although generally retro-aortic left renal vein is a rare anatomic finding, it occurs in 0.8% of the patients admitted for abdominal aortic aneurysm surgery. Surgeons fear fatal bleeding during clamping of the aorta, caused by a more caudal insertion of the retro-aortic left renal vein and a greater vulnerability of the anomalous tissue. Once such a complication occurs, a reconstruction of the retro-aortic left renal vein using a synthetic graft should be performed to obtain adequate renal venous flow and maintain renal function.

Fibrin gel -- advantages of a new scaffold in cardiovascular tissue engineering.

OBJECTIVE: The field of tissue engineering deals with the creation of tissue structures based on patient cells. The scaffold plays a central role in the creation of 3-D structures in cardiovascular tissue engineering like small vessels or heart valve prosthesis. An ideal scaffold should have tissue-like mechanical properties and a complete immunologic integrity. As an alternative scaffold the use of fibrin gel was investigated. METHODS: Preliminary, the degradation of the fibrin gel was controlled by the supplementation of aprotinin to the culture medium. To prevent tissue from shrinking a mechanical fixation of the gel with 3-D microstructure culture plates and a chemical fixation with poly-L-lysine in different fixation techniques were studied. The thickness of the gel layer was changed from 1 to 3 mm. The tissue development was analysed by light, transmission and scanning electron microscopy. Collagen production was detected by the measurement of hydroxyproline. Injection molding techniques were designed for the formation of complex 3-D tissue structures. RESULTS: The best tissue development was observed at an aprotinin concentration of 20 microg per cc culture medium. The chemical border fixation of the gel by poly-L-lysine showed the best tissue development. Up to a thickness of 3 mm no nutrition problems were observed in the light and transmission electron microscopy. The molding of a simplified valve conduit was possible by the newly developed molding technique. CONCLUSION: Fibrin gel combines a number of important properties of an ideal scaffold. It can be produced as a complete autologous scaffold. It is moldable and degradation is controllable by the use of aprotinin.

Heat shock protein upregulation lowers cytokine levels after ischemia and reperfusion.

OBJECTIVE: Studies showed that the expression of heat shock protein 70 (HSP70) by whole-body hyperthermia or warming of the heart is associated with protection against ischemia/reperfusion injury. The aim of this study is to determine a time-related response of HSP70 expression through topical cardiac warming with correlation to cytokine production. METHODS: 30 rats were divided into three groups: no heat shock, heat shocked, and controls. Heat shock was performed with 42 degrees C saline solution applied to the heart for 5, 30, and 60 min. HSP70 and cytokines were measured. RESULTS: Heat shock treated animals showed a 1.2-fold increase after 5 min (NS) in HSP70 expression, a 2.0-fold increase (p < 0.02) after 30 min, and a 2.3-fold increase (p < 0.012) after 60 min compared to controls. The IL-1beta levels decreased from 14.3 pg/ml (normal controls) to 7.1 pg/ml after 5 min, to 1.6 pg/ml after 30 min (p < 0.002), and to 1.4 pg/ ml after 60 min of heat shock treatment (p < 0.002). The TNF-alpha levels also decreased, but not significantly. CONCLUSIONS: Upregulation of HSP70 through this novel method is instant and detectable within hours. The amount of HSP70 expression induced is time dependent, showing an indirect correlation with cytokine levels. These results suggest that the protective effect of HSP70 is immediate and might be explained by reduced cytokine levels. No prior recovery period is needed.

Scaffold precoating with human autologous extracellular matrix for improved cell attachment in cardiovascular tissue engineering.

Cell attachment to a scaffold is a precondition for the development of bioengineered valves and vascular substitutes. This attachment is generally facilitated by the use of precoating factors, but some can cause toxic or immunologic side effects. Autologous extracellular matrix (ECM) is used as a precoating factor in our study. Ascending aortic tissue was cultured to obtain human myofibroblasts. Autologous ECM was extracted from the same aortic tissue. Poly(glycolic acid) (PGA) scaffolds were precoated with autologous ECM, human serum, or poly-L-lysine; the control group was pretreated with phosphate buffered saline (PBS). Myofibroblasts were seeded onto each scaffold, and the cell attachment was assayed and compared. Compared with the control group, precoating with human serum, poly-L-lysine, and ECM increased number of attached cells by 24%, 53%, and 48%, respectively. Differences between precoating groups were significant (p < 0.01), except for ECM versus poly-L-lysine. Scanning electron microscopy also demonstrated the high degree of cell attachment to the PGA fibers on scaffolds precoated with ECM and poly-L-lysine. Precoating polymeric scaffold with autologous human extracellular matrix is a very effective method of improving cell attachment in cardiovascular tissue engineering without the potential risk of immunologic reactions.

A 20-year follow-up of internal carotid artery endarterectomy with bifurcation advancement.

BACKGROUND: Carotid artery disease is a frequent cause of transient ischemic attack and of cerebral infarction. For two last decades, we have been performing endarterectomy of the internal carotid artery with bifurcation advancement. METHODS: From January 1977 until December 1997, all records of patients who underwent internal carotid artery endarterectomy with bifurcation advancement were reviewed. Data were collected from patients charts and by a questionnaire. 160 patients (80.6% men, 19.4% women, average lifetime 65.1 year) underwent a total of 181 endarterectomies with bifurcation advancement. RESULTS: The 30-day mortality was 1.9% and the postoperative stroke plus death rate 3.1%. The incidence of reoperations was 0.6% with an average follow up of 64 months. In one patient (0.6%), a significant restenosis of the repaired carotid artery was observed. The 1, 5 and 10 years neurological death free survival (including early mortality) was 99.3%, 97.2% and 92.5% and the overall survival (including early mortality) was 96.3%, 78.9% and 59.3% (Kaplan-Meier). CONCLUSIONS: The technique of the internal carotid artery endarterectomy by bifurcation advancement is a safe and reliable method for improvement of cerebral blood supply. Or foreign material or autologous vein can thus be avoided. This method offers excellent long term patency and has a notable lack of late restenosis.

Expression of adhesion molecules and cytokines after coronary artery bypass grafting during normothermic and hypothermic cardiac arrest.

OBJECTIVE: Cardiac surgery with cardiopulmonary bypass (CPB) results in vascular injury and tissue damage which involves leukocyte-endothelial interactions mediated by cytokines and adhesion molecules. This study was designed to demonstrate the effect of normothermic and hypothermic CPB to cytokine and soluble adhesion molecule levels in adults and to determine whether these levels correlate to the patients postoperative course. DESIGN AND PATIENTS: In 25 patients after normothermic and in 25 patients after hypothermic coronary artery bypass grafting with cardiopulmonary bypass (CPB), blood samples for cytokine and soluble adhesion molecule analysis were taken preoperatively, 24, 36, 48 h, and 6 days postoperatively. Soluble adhesion molecules (sE-selectin, sICAM-1) were measured by ELISA and cytokines (TNF-alpha, IL-6, IL-8) by chemilumenscent-immunoassay. Clinical data were collected prospectively. RESULTS: Postoperatively, adhesion molecule and cytokine levels were significantly elevated after CPB. Mean plasma levels of sICAM-1 was 2.4-fold higher after 6 days. Mean plasma concentration of sE-selectin peaked after 48 h with a 2-fold increase compared to normothermic conditions. In the hypothermia group sICAM-1, sE-selectin, IL-6, and IL-8 showed significantly higher levels (P<0.0057, P<0.0012, P<0.0419, P<0.0145) after 24 h compared to the normothermia group. No clinical differences were seen. CONCLUSION: Adhesion molecules and cytokines are elevated after CPB. Patients after hypothermic CPB show significant higher sICAM-1, sE-selectin, IL-6, and IL-8 levels after 24 h compared to normothermic conditions. These results are mainly due to longer CPB and crossclamp times but do not alter the patient's postoperative course.