Biomedical subjects

Marko Turina

Publications and source records attributed to Marko Turina.

30 records · Page 2Linked to original sources

PubMed2003

[Totally artificial training model for coronary heart surgery: the renunciation of animal experiments?].

AIM: Animal protection laws will lead to stricter and more selective criteria thus resulting in a decline of available animals. Yet to train cardiac surgical skills a totally artificial training model was developed. DESCRIPTION OF THE TRAINING MODEL: The model is based on differently hardened polyurethane. Cover is a 1:1 replica of the human thoracic wall. Disposable coronaries are integrated in the heart-model. Vessels and part of the ascending aorta can be rinsed. By means of a newly designed air-pump stroke volume, heart-rate and rhythm can be adjusted. EXPERIENCES: Set-up of the model is easy and quick. Accustomed instruments can be used. Handling of artificial tissue is nature-like. Degree of difficulty is dependent on stroke volume, heart rate, arrhythmia, vessel-size and vessel-quality. CONCLUSION: The phantom helps to achieve confidence in coronary revascularisation. It facilitates an accompanying training for the less-trained as well as the skilled surgeon. The nature-like characteristics will help to reduce animal experiments in future.

Animal Testing Alternatives↗

PubMed2003

Early results of using the bovine jugular vein for right ventricular outflow reconstruction during the Ross procedure.

OBJECTIVE: To study the early function of the bovine jugular vein (BJV) when used for right ventricular outflow tract (RVOT) reconstruction during the Ross procedure. METHODS: Seventeen consecutive patients (median age, 12 years; range, 30 days to 40 years) who had undergone a Ross procedure with RVOT reconstruction using a BJV were reviewed. Nine patients had prior balloon valvotomy (n = 6) and/or surgical aortic valvotomy (n = 4). Additional procedures included a reduction-plasty of the ascending aorta (5 patients), a Konno procedure (2 patients), a mitral valve repair/replacement (2 patients), and others (3 patients). The size of the BJV ranged from 12 to 22 mm (median, 20 mm). RESULTS: There were no early or late deaths. None of the patients encountered any significant postoperative complications. The neo-aortic valve showed good function in all patients with no more than trivial insufficiency. At a median follow-up period of 11 months, the frequency of freedom from BJV graft dysfunction/reintervention/reoperation was 100%. One patient had moderate insufficiency of the BJV in a perioperative examination that regressed to mild insufficiency during follow-up. Overall, none of the patients had more than mild insufficiency at follow-up. Four patients showed a flow acceleration of more than 250 cm/s (equivalent to a gradient of 25 mm Hg) across the BJV, and the remaining patients had lower gradients. CONCLUSIONS: The BJV, when used to replace the pulmonary valve in the Ross procedure, showed excellent function in the early phase. The large size range and easy availability of this valved conduit are particularly attractive. Further followup is needed to determine the long-term results of its use.

Adolescent↗

PubMed2003

A single bicaval venous cannula used for optimization of endoscopic robotically assisted procedures of the heart.

Robotically assisted heart operation is one of the minimally invasive approaches that have revolutionized many surgical procedures. Robotic procedures on the heart, however, are by no means routine, and their optimization requires development of new instruments and techniques. Described here is the robotically assisted use in a sheep model of a new peripherally inserted bicaval venous cannula in the totally endoscopic closure of atrial septal defect. The exposure of the surgical target area was successful with no obstructions in the surgical view. The cannula shows sufficient flow characteristics for cardiopulmonary bypass. Subsequent suturing of the atrial septum defect was achieved without complications in the 4 experimental animals.

Animals↗

PubMed2002

Study of coronary sinus flow reserve through transesophageal Doppler echocardiography in normal subjects.

OBJECTIVE: To evaluate the Coronary Flow Reserve in the Coronary Sinus through transesophageal Doppler echocardiography in normal subjects. METHODS: We obtained technically adequate flow samples for analysis in 10 healthy volunteers (37+/-8 years, 5 men) with no history of heart or systemic disease and with mean left ventricular mass index by transthoracic echocardiography of 87+/-18 g/m2. Coronary sinus flow velocity was recorded within the coronary sinus with the patient in a resting condition and during intravenous adenosine infusion at a dose of 140 micro g/kg/min for 4 minutes. Recording of coronary sinus blood flow was possible in all cases with measurement of peak systolic, diastolic, and retrograde velocities (PSV, PDV, and PRV, cm/sec), mean systolic and diastolic velocities (MSV and MDV, cm/sec), and systolic and diastolic velocity time integral (VTI S and VTI D, cm/sec). RESULTS: The coronary flow reserve was calculated as the ratio between the blood flow in the basal state and the maximum measured hyperemic blood flow with adenosine infusion. Results are shown as mean and standard deviations. (CFR = PSV + PDV - PRV/basal PSV): 1st min = 2.2+/-0.21; 2nd min = 3+/-0.3; 3rd min = 3.4+/-0.37; 4th min = 3.6 +/- 0.33. CONCLUSION: Although coronary sinus flow had significantly increased in the first minute, higher velocities were seen at third and fourth minutes, indicating that these should be the best times to study coronary sinus flow with intravenous adenosine in continuous infusion.

Adenosine↗

PubMed2002

Human umbilical cord cells: a new cell source for cardiovascular tissue engineering.

BACKGROUND: Tissue engineering of viable, autologous cardiovascular constructs with the potential to grow, repair, and remodel represents a promising new concept for cardiac surgery, especially for pediatric patients. Currently, vascular myofibroblast cells (VC) represent an established cell source for cardiovascular tissue engineering. Cell isolation requires the invasive harvesting of venous or arterial vessel segments before scaffold seeding, a technique that may not be preferable, particularly in pediatric patients. In this study, we investigated the feasibility of using umbilical cord cells (UCC) as an alternative autologous cell source for cardiovascular tissue engineering. METHODS: Human UCC were isolated from umbilical cord segments and expanded in culture. The cells were sequentially seeded on bioabsorbable copolymer patches (n = 5) and grown in vitro in laminar flow for 14 days. The UCC were characterized by flow cytometry (FACS), histology, immunohistochemistry, and proliferation assays and were compared to saphenous vein-derived VC. Morphologic analysis of the UCC-seeded copolymer patches included histology and both transmission and scanning electron microscopy. Characterization of the extracellular matrix was performed by immunohistochemistry and quantitative extracellular matrix protein assays. The tissue-engineered UCC patches were biomechanically evaluated using uniaxial stress testing and were compared to native tissue. RESULTS: We found that isolated UCC show a fibroblast-like morphology and superior cell growth compared to VC. Phenotype analysis revealed positive signals for alpha-smooth muscle actin (ASMA), desmin, and vimentin. Histology and immunohistochemistry of seeded polymers showed layered tissue formation containing collagen I, III, and glycoaminoglycans. Transmission electron microscopy showed viable myofibroblasts and the deposition of collagen fibrils. A confluent tissue surface was observed during scanning electron microscopy. Glycoaminoglycan content did not reach values of native tissue, whereas cell content was increased. The biomechanical properties of the tissue-engineered constructs approached native tissue values. CONCLUSIONS: Tissue engineering of cardiovascular constructs using UCC is feasible in an in vitro environment. The UCC demonstrated excellent growth properties and tissue formation with mechanical properties approaching native tissue. It appears that UCC represent a promising alternative autologous cell source for cardiovascular tissue engineering, offering the additional benefits of using juvenile cells and avoiding the invasive harvesting of intact vascular structures.

Actins↗

PubMed2002

The anatomy of the aortic root.

OBJECTIVE: Since the aortic root preserving methods are spreading in heart surgery, the importance of aortic root anatomy is increasing. The surgical and anatomical descriptions of the aortic root are not always congruent. Therefore, the present study focuses on the surgical aspects of the aortic root anatomy. METHODS: We measured the distances between the three commissures, the distances between the basal point of the sinus and the sinotubular junction and the heights of the sinuses. The circumference of the sinotubular junction and the annuli fibrosi were also obtained. In addition, the volume of every sinus was directly measured. Finally both vertical and horizontal histological sections of annuli fibrosi were made. RESULTS: All measured parameters were averaged and the standard deviation (SD) was calculated, except in the case of the tilt angle. The distance for the right sinus commissures was 18.82 mm (SD 1.93 mm), and that of the non- and left coronary sinus were 17.43 (SD 2.06) and 15.21 (SD 1.88) mm, respectively. The mean height of the right, non- and left coronary sinus were 19.45 (SD 1.91), 17.68 (SD 1.77) and 17.45 (SD 1.39) mm, respectively. These differences between the height of the sinuses determines a mean tilt angle of 5.47 degrees for the sinotubular junction and aortic root base. The mean circumference of the aortic root base and of the sinotubular junction was 69.20 (SD 6.93), and 65.82 (SD 8.31) mm, respectively. Mean volumes of the right, non- and left coronary sinuses were 1.6 (SD 0.34), 1.33 (SD 0.27) and 1.04 (SD 0.23l) ml. According to the histological sections we can say that the histological border of the annuli fibrosi is positioned at the interleaflate triangles. CONCLUSION: According to the measured data we can state that all parameters follow the pattern in which the right sinus structures had the greatest dimensions followed by the non coronary sinus, and finally the left coronary sinus. The tilt angle for aortic root base and sinotubular junction, and the difference in the diameters could be of hemodynamic and of surgical relevance

Analysis of Variance↗

PubMed2002

Results of surgery for irreversible moderate to severe mitral valve regurgitation secondary to myocardial infarction.

OBJECTIVE: Moderate to severe irreversible mitral regurgitation secondary to myocardial infarction is an independent risk factor for reduced long-term survival. Late effects of correction of mitral incompetence concomitant with coronary artery bypass grafting (CABG) are less well known and the choice of mitral valve procedure is still debated. METHODS: From 1988 to 1998, 93 consecutive patients (mean age 63+/-9 years) were treated for moderate to severe irreversible mitral regurgitation secondary to myocardial infarction; 84 were in NYHA functional class III-IV and 19 were in cardiogenic shock. Thirty-seven patients underwent emergency surgery. Perioperative intraaortic balloon pump (IABP) was necessary in 33 patients. Follow-up ranged from 6 months to 12 years (mean 51 months+/-41). RESULTS: Mitral valve was repaired in 30 patients and replaced in 63. Replacement was preferably performed in patients with major displacement of papillary muscle and in patients with acute papillary muscle rupture. CABG (3.4 distal anastomoses) was performed in all patients and was complete in 92%. Early mortality was 15% (14/93). Multivariable analysis identified need for IABP (P=0.005) and COPD (P=0.02) as risk factors for early death. Emergency surgery had only a trend (P=0.15) for increased mortality; age, low ejection fraction, repair vs. replacement had no influence. Actuarial survival rates at 1, 5 and 10 years were 81, 65 and 56%, respectively. Late survival was similar in patients with replacement or repair (P=0.46). At last follow-up, all but one patient were in NYHA functional class I or II. CONCLUSIONS: Combined mitral valve procedure and myocardial revascularization, as complete as possible, for moderate to severe mitral regurgitation secondary to myocardial infarction achieve satisfactory early and late outcome despite the increased operative mortality. Acute papillary muscle rupture, severe restriction of the mitral valve by major displacement of the papillary muscle are better managed by valve replacement.

Adult↗

PubMed2002

Repair of postinfarction dyskinetic LV aneurysm with either linear or patch technique.

OBJECTIVES: Controversy still exists regarding the optimal surgical technique for postinfarction dyskinetic left ventricular aneurysm (LVA) repair. We compared the efficacy of two established techniques, linear vs. patch remodeling, for repair of dyskinetic LVA. PATIENTS AND METHODS: From 1989 to 1998, 95 (16 women, 79 men) consecutive patients were operated on for postinfarction dyskinetic LVA. Thirty-four patients underwent patch remodeling (R) and 61 linear (L) repair. The mean age was 61.1+/-8.5 years. Indications for surgery alone or in combination included angina in 72 patients, dyspnea in 64 and ventricular tachycardia in 41. Thirty-seven patients had a history of congestive heart failure (R 13 (38%), L 24 (39%), NS). The mean ejection fraction (EF) with aneurysm was 0.29+/-0.09 in R vs. 0.35+/-0.10 in L (P<0.04), whereas the mean EF without aneurysm was 0.43+/-0.11 in R vs. 0.46+/-0.08 in L (P=0.3). Seventy-one aneurysms were anterior (R 30 (88%), L 41 (68%), P<0.05). Concomitant coronary artery bypass grafting was performed in 84 patients (R 29 (85%), L 55 (90%), NS). Follow-up ranged from 1 to 12 years (mean 5.6+/-3.4 years, median 6.1 years). RESULTS: Early mortality was 8% (n=8) (R 4, L 4, NS). Survival at 1, 5 and 10 years was 88, 73, and 44%, respectively. It did not differ significantly between R (1 and 5 year survival 85, 66%) and L (90, 76%, P=0.58). Preoperative risk factors for mortality were history of congestive heart failure (1 and 5 year survival 81 and 57% vs. 90 and 78%, respectively, hazard ratio (HR)=1.95, P<0.05), non-anterior localization of the aneurysm (86 and 49% vs. 86 and 77%, HR=2.06, P<0.05), history of thromboembolic events (57 and 19% vs. 89 and 74%, HR=3.27, P<0.05), and left ventricular EF (HR=0.97 per %, P=0.05). At late follow-up the mean functional class was 1.8+/-0.6 in long-term survivors (preoperative 2.9+/-0.9, P<0.001) with no difference between the groups. CONCLUSIONS: The technique of repair of postinfarction dyskinetic LVA should be adapted in each patient to the cavity size and extent of the scarring process into the septum and subvalvular mitral apparatus. Applying these considerations to the choice of the technique of repair, both techniques achieved satisfactory results with respect to perioperative mortality, late functional status and survival.

Aged↗

PubMed2002

Short-term results of endovascular AAA repair with the Excluder bifurcated stent-graft.

PURPOSE: To evaluate the safety and efficacy of endovascular abdominal aortic aneurysm (AAA) repair with a commercial modular stent-graft. METHODS: Between February 1998 and May 2000, 66 consecutive patients (56 men; mean age 70 years, range 51-87) were recruited for a single-center study to examine the safety and efficacy of the Excluder stent-graft for endovascular AAA repair. The patients were predominantly asymptomatic (2 symptomatic) and categorized as ASA III or IV (62, 94%), with aneurysms that ranged from 35 to 89 mm in diameter (mean 56). Surveillance included clinical examination and computed tomographic aortography at discharge, 6 weeks, and at 6, 12, and 24 months. RESULTS: All endoprostheses were implanted as intended, but 1 patient succumbed to an intraprocedural brainstem infarction (1.5% 30-day mortality rate). The major and minor morbidity rates were 21% and 4.5%, respectively. Primary technical success at discharge was 68% (45/66), largely as the result of a 30% (20/66) endoleak rate. The aneurysm exclusion rate at 30 days was 88%. During the mean 5.8-month follow-up, no device migration, limb kinking, aneurysm rupture, or limb thrombosis was observed. CONCLUSIONS: Endoluminal AAA repair with the bifurcated Excluder stent-graft is safe and efficacious in the short term. Longer surveillance will have to demonstrate if the excellent early results can be maintained over the years.

Aged↗

PubMed2002

Surgical management of acute mitral valve regurgitation due to post-infarction papillary muscle rupture.

BACKGROUND AND AIM OF THE STUDY: Acute myocardial infarction associated with mitral papillary muscle rupture and cardiogenic shock carries a high mortality. Data relating to early and late survival after emergency mitral valve surgery and concomitant complete coronary artery revascularization in this patient population were analyzed. METHODS: Between January 1988 and December 1998, 21 consecutive patients (mean age 62+/-9.7 years) underwent emergency coronary and concomitant mitral valve surgery for acute myocardial infarction and mitral papillary muscle rupture associated with cardiogenic shock. Mitral valve replacement was performed in 19 patients (90%), and mitral valve repair in two (10%). An average of 2.2 distal anastomoses per patient was performed. Revascularization was complete in 19 patients (90%). Preoperatively, intra-aortic balloon pumping was used in 11 patients (52%), and two (10%) had salvage surgery when arriving at the operating room under cardiopulmonary resuscitation. Early and late follow up was complete; mean follow up was 5+/-3 years (range: 16 months to 12 years). RESULTS: Thirty-day mortality was 19% (4/21), with two cardiac-related early deaths (10%). Early morbidity included perioperative stroke in 6% (1/17), myocardial infarction in 6% (1/17), and need for hemodialysis in 18% (3/17). There were three late deaths; one was cardiac-related. Actuarial survival at one, five and 10 years was 81, 68 and 56%, respectively. All survivors were in NYHA class I or II. CONCLUSION: Emergency surgery for acute post-infarction mitral papillary muscle rupture is justified, even as a salvage procedure. Concomitant mitral valve surgery and complete coronary artery revascularization achieve acceptable survival rates and satisfactory functional results.

Acute Disease↗

PubMedDate not supplied

Increased susceptibility of the left compared to the right ventricle to remote ischemia/reperfusion injury in human C1-inhibitor-overexpressing transgene mice.

Acute myocardial injury has been demonstrated as a remote sequela of severe lower torso ischemia-reperfusion (I/R) due to proinflammatory events. In a model of I/R injury, administration of C1 esterase inhibitor (C1-Inh) reduces myocardial necrosis. We investigated the susceptibility of the left (LV) versus right ventricle (RV) and the protective effect of transgenic C1-Inh-overexpressing mice. Two groups of mice (n = 6) underwent a 2-h lower torso ischemia followed by 3 h of reperfusion: transgenic and wild type with sham-operated controls. Animals were then injected with (125)I bovine albumin. Heart was removed and samples from right and left ventricular free wall were harvested, weighted, and radioactivity was determined. Permeability index for wild-type animals in the RV was 0.22 +/- 0.04, compared to 0.17 +/- 0.07 in controls (NS), and in the LV 0.36 +/- 0.08, compared to 0.21 +/- 0.05 in controls (p <.01). The LV showed a significantly higher value compared to the right (0.22 +/- 0.04 vs. 0.36 +/- 0.08, p <.01). No difference was seen in the RV between transgenic and wild-type mice; however, in the LV the values decreased significantly in transgenic animals (p <.015). Thus, remote myocardial injury after lower torso I/R is present in both ventricles; however, the LV seems to be more susceptible as assessed by albumin permeability. Inhibition of the classic complement cascade may be a promising therapeutic approach for myocardial protection in reperfusion injury.

Acute Disease↗

PubMedDate not supplied

A new approach to completely autologous cardiovascular tissue in humans.

In cardiovascular tissue engineering, synthetic or biologic scaffolds serve as templates for tissue development. Currently used scaffolds showing toxic degradation and immunogenic reactions are still far from ideal. We present a new alternative method to develop completely autologous human tissue without using any scaffold materials. Human vascular cells of arterial and venous origin were cultured to form cell sheets over a 4 week period under standard conditions. Thereafter, cell sheets of each origin were folded and cultured in a newly developed frame device for an additional 4 weeks. Controls remained under standard culture conditions. Tissue development was evaluated by morphology and biochemical assays. The formation of multilayered cell sheets and production of extracellular matrix were observed in all groups. Folded and framed neo-tissue showed a solid structure, with increased matrix formation and tissue organization when compared with the control groups. DNA content indicated significantly lower cell proliferation, and hydroxyproline assay indicated significantly higher collagen content in the framed cell sheets. We present a new approach to the engineering of cardiovascular tissue without the use of biodegradable scaffold material. Three-dimensional, completely autologous human tissue may be developed on the basis of this structure, thus avoiding scaffold induced toxic degradation or inflammatory reaction.

Blood Vessels↗