Search PubMed⌕ Search

Biomedical subjects

E Wolner

Publications and source records attributed to E Wolner.

At least 145 records · Page 8Linked to original sources
PubMed1998

Intermediate follow up of the TEKNA bileaflet valve.

BACKGROUND AND AIM OF THE STUDY: The study aim was to collect intermediate clinical data on the TEKNA bileaflet valve. METHODS: This nine-center clinical study involved 884 patients implanted between June 1990 and October 1993. The population consisted of 522 (59.0%) males and 362 (41.0%) females. Mean age at implant was 59.1 +/- 11.8 years (range: 14.7 to 88.4 years). Indication for valve replacement was dependent on the position: stenosis was the predominant reason in the aortic position; regurgitation was more pronounced for the mitral position. A total of 261 (29.5%) patients underwent concomitant procedures. Mean follow up is 2.7 +/- 1.2 years; total follow up is 2386.1 patient-years (pt-yr). RESULTS: Total operative (< or = 30 days postoperative) mortality rate was 3.7%; seven patients (0.8%) died due to valve-related causes. Total postoperative (> 30 days postoperative) mortality rate was 2.5%/pt-yr and included a valve-related mortality rate of 1.1%/pt-yr. The following valve-related complication rates (%/pt-yr) were reported for the long-term postoperative period: thromboembolism 0.6; valve thrombosis 0.3; bleeding events 1.5; non-structural deterioration 0.6; and endocarditis 0.4. No structural valve deterioration was reported. Actuarial freedom at four years was: overall survival rate 86.9 +/- 1.4%; valve-related survival rate 94.7 +/- 1.0%; freedom from thromboembolism 96.8 +/- 0.9%; valve thrombosis 99.3 +/- 0.3%; endocarditis 98.5 +/- 0.5%; bleeding events 94.3 +/- 1.0%; and non-structural deterioration 98.2 +/- 0.6%. CONCLUSIONS: The data indicate that observed mortality is due mainly to non-valve-related disorders. Risk of thromboembolic and bleeding events was low (0.9%/pt-yr and 1.5%/pt-yr, respectively). We conclude that this valve is safe and efficacious for use.

Actuarial Analysis↗
PubMed1998

Acidic glycoproteins accumulate in calcified areas of bioprosthetic tissue.

BACKGROUND AND AIMS OF THE STUDY: This study was performed to evaluate the role of collagen fibrils, cellular elements and matrix proteins in calcification of glutaraldehyde (GA)-fixed bioprosthetic material. METHODS: Lyoplant (lyophilized bovine pericardium, type I collagen) was processed according to three protocols. DF-group (double fixation): after conventional fixation in GA (0.5% for 72 h; storage 0.25%) Lyoplant was implanted subcutaneously into rats for 5 days. Specimens were explanted and re-fixed (conventional fixation), followed by autologous or homologous reimplantation in rats for 21 or 63 days. CF-group (conventional fixation): Lyoplant patches were conventionally fixed (as DF-group), kept in 0.9% saline for one week, and then autologously and homologously reimplanted. GF-group (high-concentration GA): Lyoplant patches were processed (as GF-group) but 0.5% GA was used for tissue storage. Explanted specimens were studied by light microscopic histochemistry; calcium contents were measured by atomic absorption spectroscopy. RESULTS: Severe calcification occurred in the DF-group without differences between autologous and homologous reimplantation. In CF- and GF-groups, calcification was negligible, but immunologic response against homologous implants was accompanied by increased calcium content. Histologic characterization of matrix material in calcified areas revealed oxyphilic glycoproteins, identified as sialoglycans. CONCLUSIONS: Modification of extracellular matrix by GA is assumed as essential to cause calcification of bioprosthetic material. Calcium deposition and accumulation of sialoglycans are simultaneous events. A specific role of this glycoprotein for calcification has to be considered.

Analysis of Variance↗
PubMed1997

Epicardial branches of the coronary arteries and their distribution in the rabbit heart: the rabbit heart as a model of regional ischemia.

BACKGROUND: The rabbit heart has been frequently used to study regional ischemia, but there is hardly any detailed information on the epicardial branching of the coronary arteries. Therefore, we wanted to determine whether there is a constant branching pattern and how comparable this pattern is with the human heart. METHODS: We investigated epicardial branching of the coronary arteries in 30 adult rabbit hearts. For vessel visualisation, we used injections of Technovit, followed by corrosion. RESULTS: We found that there is not one constant pattern but rather a bifurcation or a trifurcation of the arteria coronaria sinistra (15 of 15 hearts). The left coronary artery is always the dominant artery; a vessel comparable to the human ramus interventricularis anterior is rarely found in the bifurcation type. The ramus circumflexus is a constant but minor branch of the posterior or posterolateral division and does not originate directly from the main stem of the left coronary artery, as it does in humans. As a consequence, ligation of the left ramus interventricularis anterior leads to severe ischemic injury only where trifurcation exists (50% of our population). A ligation of the ramus circumflexus proximal to its origin produces a large posterolateral infarction in the bifurcation type (50% of our population). CONCLUSIONS: Because a defined ischemic area is difficult to reproduce under these anatomical conditions, the rabbit heart may be a model only for regional ischemia if the investigator is knowledgeable about the distributions of the coronary arteries.

Animals↗
PubMed1997

Flow characteristics and required control algorithm of an implantable centrifugal left ventricular assist device.

As the clinical application of LVADs has increased, attempts have been made to develop smaller, less expensive, more durable and efficient implantable devices using rotary blood pumps. Since chronic circulatory support with implantable continuous-flow LVADs will be established in the near future, we need to determine the flow characteristics through an implantable continuous-flow LVAD. This study describes the flow characteristics through an implantable centrifugal blood pump as a left ventricular assist device (LVAD) to obtain a simple non-invasive algorithm to control its assist flow rate adequately. A prototype of the completely seal-less and pivot bearing-supported centrifugal blood pump was implanted into two calves, bypassing from the left ventricle to the descending aorta. Device motor speed, voltage, current, flow rate, and aortic blood pressure were monitored continuously. The flow patterns revealed forward flow in ventricular systole and backward flow in diastole. As the pump speed increased, an end-diastolic notch became evident in the flow profile. Although the flow rate (Q [l/min]) and rotational speed (R [rpm]) had a linear correlation (Q = 0.0042R - 5.159; r = 0.96), this linearity was altered after the end-diastolic notch was evident. The end-diastolic notch is considered to be a sign of the sucking phenomenon of the centrifugal pump. Also, although the consumed current (I [A]) and flow rate had a linear correlation (I = 0.212Q + 0.29; r = 0.97), this linearity also changed after the end-diastolic notch was evident. Based upon the above findings, we propose a simple algorithm to maintain submaximal flow without inducing sucking. To maintain the submaximal flow rate without measuring flow rate, the sucking point is determined by monitoring consumed current according to gradual increases in voltage.

Algorithms↗
PubMed1997

Emergency aortic valve replacement for critical aortic stenosis. A lifesaving treatment for patients with cardiogenic shock and multiple organ failure.

OBJECTIVE: To demonstrate that emergency aortic valve replacement can be successfully performed in patients with critical aortic stenosis and reduced left ventricular function even in cardiogenic shock with associated severe multiple organ failure. DESIGN: Retrospective, consecutive case series. SETTING: Multidisciplinary intensive care unit of a tertiary care university hospital. PATIENTS: Five patients admitted to the intensive care unit with critical aortic stenosis (aortic valve area 0.56 +/- 0.13 cm2) and greatly reduced left ventricular ejection fraction (20 +/- 3%) in prolonged cardiogenic shock and associated multiple organ failure (Multiple organ failure score 6.8 +/- 0.5; Acute Physiology, Age, and Chronic Health Evaluation III score 91 +/- 27). INTERVENTION: Emergency aortic valve replacement. RESULTS: All patients survived with full recovery of organ function. At follow-up (18 +/- 10 months) all patients were in New York Heart Association functional class I or II with improvement of left ventricular ejection fraction to 48 +/- 25%. CONCLUSIONS: This excellent outcome suggests that emergency aortic valve replacement should be strongly considered in patients with critical aortic stenosis even in cardiogenic shock and multiple organ failure.

Adult↗
PubMed1997

Prevention of air leaks after pulmonary wedge resection.

Prolonged air leak after a lung volume reduction operation for pulmonary emphysema is a major cause of morbidity and prolonged hospital stay. Staple line reinforcement is recognized as an effective adjunctive technique for decreasing the occurrence of air leaks after pulmonary wedge resection. Numerous materials have been used for staple-line reinforcement. We use expanded polytetrafluoroethylene sleeves that fit over the arms of surgical staplers to facilitate staple-line reinforcement in both thoracoscopic and open lung volume reduction procedures. The expanded polytetrafluoroethylene sleeves do not require rinsing or special handling; they are easy to use and effective in preventing air leaks. We had no prolonged air leaks or infections in any of the cases in which we used the sleeves.

Humans↗
PubMed1997

Functional improvement after volume reduction: sternotomy versus videoendoscopic approach.

BACKGROUND: Volume reduction has been proved to increase ventilatory mechanics in diffuse, nonbullous lung emphysema. However, the best approach is still controversial. METHODS: We retrospectively compared the perioperative data of and functional results in 15 patients having sternotomy (group I) with those of 15 patients having a videoendoscopic approach (group II). RESULTS: The 30-day mortality was 2 patients in group I and 1 patient in group II. Mean duration of chest tube drainage was 8.7 +/- 1.8 days and 8.0 +/- 1.9 days and mean hospital stay, 12.3 +/- 1.9 and 12.5 +/- 2.1 days in groups I and II, respectively. Work of breathing decreased from 1.89 +/- 0.33 J/L and 1.76 +/- 0.22 J/L preoperatively to 0.75 +/- 0.06 J/L and 0.8 +/- 0.06 J/L (p < 0.01 and p < 0.05, respectively) after 3 months; and intrinsic positive end-expiratory pressure decreased from 7.15 +/- 1.31 cm H2O and 6.24 +/- 1.33 cm H2O to preoperatively 0.79 +/- 0.46 cm H2O and 1.13 +/- 0.44 cm H2O (p < 0.005 and p < 0.01, respectively) after 3 months in groups I and II, respectively. Forced expiratory volume in 1 second increased from preoperative values of 21.6% +/- 2.9% and 25.3% +/- 2.4% of predicted to 34.5% +/- 5.0% and 40.9% +/- 7.5% of predicted after 3 months (p < 0.05 in both groups) in groups I and II, respectively. CONCLUSIONS: Both surgical approaches resulted in similar substantial improvement in lung function and physical fitness. The incidence of air leakage, the duration of chest tube drainage, and the hospital stay were the same for both procedures.

Case-Control Studies↗
PubMed1997

Five-year follow-up after heart valve replacement with the CarboMedics bileaflet prosthesis.

BACKGROUND: The CarboMedics valve is a relatively new, low-profile, bileaflet, mechanical prosthesis. The results of a prospective follow-up study after valve replacement with this prosthesis in a university hospital are presented. METHODS: We implanted 640 CarboMedics prostheses in 583 patients in the aortic (n = 359), mitral (n = 167), or aortic and mitral positions (double valve replacement; n = 57). Patient ages ranged from 11 to 81 years (mean age, 58 +/- 12.3 years). RESULTS: Overall hospital mortality was 9.0%; however, when high-risk urgent cases were removed from the calculation, the operative mortality fell to 4.5%. Follow-up was 98% complete, comprising 2,027 patient-years for a mean follow-up of 44 months (range, 6 to 72 months). Actuarial freedom from complications (linearized rates in parentheses) was as follows: late mortality, 85% +/- 2.0% (2.3%/patient-year); thromboembolism, 92% +/- 1.1% (1.6%/patient-year); anticoagulation-related hemorrhage, 87% +/- 1.2% (2.8%/patient-year); prosthetic valve endocarditis, 98% +/- 0.5% (0.1%/patient-year); and overall valve-related morbidity and mortality, 76% +/- 2.1% (4.3%/ patient-year). CONCLUSIONS: The CarboMedics valve shows a low rate of valve-related complications comparable with other new mechanical heart valve prostheses.

Adolescent↗
PubMed1997

Surgical treatment of aortic arch aneurysms in profound hypothermia and circulatory arrest.

BACKGROUND: This study was undertaken to define the factors that influence mortality rate and neurologic outcome after repair of the aortic arch and various portions of the thoracic aorta in patients with profound hypothermia and circulatory arrest. METHODS: Between November 1986 and January 1996, 105 patients were treated surgically for aortic disease involving the transverse aortic arch. Profound hypothermic circulatory arrest and selective brachiocephalic perfusion was used in all patients. In 19 patients retrograde cerebral perfusion was instituted during the period of circulatory arrest. Independent predictors for 30-day mortality and permanent neurologic deficits were evaluated by multiple logistic regression. RESULTS: Thirty-day mortality for the entire group was 19% (20/105); 21.2% for urgent versus 15.4% for elective cases, respectively. Statistical analysis showed that age is the most important factor that significantly influences mortality rate (p < 0.0145) and neurologic outcome (p < 0.006). Variables such as circulatory arrest time (p < 0.24), previous cardiac or aortic operations (p < 0.19), and sex (p < 0.55) failed to show any influence on mortality rate. Permanent neurologic deficits were diagnosed in 12.9% (11/85) of the patients. CONCLUSIONS: The incidence of permanent neurologic dysfunction as well as the mortality rate are predominantly related to the age of the patient. In this patient group, statistical analysis failed to show a direct correlation between duration of circulatory interruption and neurologic outcome.

Adolescent↗
PubMed1997

Myocardial revascularization without cardiopulmonary bypass in pigs: a comparison between beta-blockers and Ca2+-channel blockers.

The purpose of this study was to develop the surgical technique for internal mammary artery grafting on the beating heart. In 10 pigs, heart rate was reduced with esmolol (n = 5) or verapamil (n = 5). In addition, the anti-ischaemic and anti-arrhythmic potencies of these drugs were investigated. Haemodynamics, mechanical function and ischaemia-sensitive laboratory measurements were assessed perioperatively. There were no differences in pre-ischaemic data including ischaemic clamping time of the left anterior descending artery. At the end of ischaemia haemodynamic parameters were significantly lower in the esmolol-group (P < 0.05). In the verapamil-group, one pig died from ventricular fibrillation during ischaemia, and one showed fibrillation during reperfusion (P < 0.01). There were no differences in cardiac function or enzymes between the groups. Reduction of heart rate was provided by both drugs, but no conclusive evidence was provided with regard to additional anti-ischaemic and anti-arrhythmic protection.

Adrenergic beta-Antagonists↗
PubMed1997

The use of profound hypothermia and circulatory arrest in operations on the thoracic aorta.

OBJECTIVE: This retrospective study reviews the contemporary surgical outcome of our patients undergoing operations on thoracic aneurysms in deep hypothermic circulatory arrest. METHODS: Between January 1989 and February 1995, 279 patients were operated on in our institution on various portions of the aorta. In 143 patients (97 male, 46 female), deep hypothermia and circulatory arrest were used as the standard operative technique. Patients age ranged from 16 to 83 years (mean 55). Final indication for operation was dissection Type A in 80 patients (61 acute, 19 chronic), dissection Type B in 21 patients (17 acute, 4 chronic) and atherosclerotic aneurysms in 42 patients (11 acute, 31 chronic). 16 patients were operated under preoperative unstable hemodynamic conditions, 6 patients had been resuscitated preoperatively. Surgical technique included cardiopulmonary bypass with femoral artery cannulation. For added cerebral protection all patients received Cortisone and barbiturates right before circulatory arrest (confirmed by 0-EEG). The segment of the aorta containing the area with the aneurysm, was resected and replaced with a tubular albumin coated graft. RESULTS: The 30-day mortality was 31.15% (19/61) in the acute and 23.52% (4/19) in the chronic type A dissection group, 35.29% (6/17) in the acute and 25% (1/4) in the chronic type B group, 36.3% (4/11) in the acute and 22.58% (7/31) in the chronic atherosclerotic group. Causes of postoperative death in order of frequency were: multiorgan failure (n = 15), myocardial failure (n = 13), bleeding (n = 4), sepsis (n = 4), myocardial infarction (n = 3) and stroke (n = 2). CONCLUSION: Despite rather high mortality rates in the acute aneurysm groups, the technique of profound hypothermic circulatory arrest represents a relatively safe method for operations on the thoracic aorta.

Adolescent↗
PubMed1997

Increased pulmonary flow velocities in oversized homografts in patients after the Ross procedure.

OBJECTIVE: Between September 1991 and July 1996, 60 patients (mean age 29.8 +/- 9 years; range 5-57) underwent aortic root replacement with pulmonary autograft, a viable biologic and nondegenerating substitute. The pulmonary root was replaced with cryopreserved homografts from cardiac transplant recipients. The aim of this study was to evaluate differences in early valve function of viable and cryopreserved allografts. METHODS: All patients had Doppler echocardiographic examinations preoperatively, at discharge from hospital and 54 patients at 1 year follow-up. We measured aortic and pulmonary peak flow velocities with continuous and pulsed-wave Doppler, and graded aortic and pulmonary insufficiency (AI, PI) with color Doppler flow (grade 0-IV). Intraoperatively, the diameters of the pulmonary root and the pulmonary homograft were measured with standard valve probes and matched to body surface area. RESULTS: Pulmonary peak flow velocity (PVmax) increased significantly from preoperative 0.87 +/- 0.11 m/s to 1.30 +/- 0.34 m/s postoperatively (P < 0.001). The implanted homografts (mean 25.9 +/- 2.4 mm) were larger than their native pulmonary diameter (mean 23.3 +/- 1.8 mm) in all patients. Homograft size matched for body surface area (BSA) did not correlate with increased PVmax. There was a significant increase of PVmax at follow-up (FU) since discharge, also (1.83 +/- 0.53 m/s; P < 0.001). Pulsed-wave Doppler demonstrates that increase of PVmax is located directly at the homograft leaflets and not at the anastomoses. Aortic peak flow velocities (AVmax) were normal postoperatively and at FU (post = 1.35 +/- 0.35 m/s; FU = 1.17 +/- 0.27 m/s). There was no significant change in AI or PI since discharge (AI FU = 0.8 +/- 0.4; PI FU = 0.7 +/- 0.5). Eight patients with fever and symptoms diagnosed as post-pericardiotomy syndrome had significantly higher PVmax at FU (PVmax = 2.41 +/- 0.40 m/s; P < 0.02). CONCLUSIONS: The Ross procedure leads to normal AVmax but significant increase of PVmax even in oversized cryopreserved homografts immediately after surgery. Further increase of PVmax without changes in AVmax in the first year demonstrates that changes in flow velocities are valve related and not due to increase in cardiac output. Further investigations will be necessary to determine whether this observation is due to valve rejection or early leaflet degeneration and treatment with immunosuppressive therapy is warranted.

Adult↗
PubMed1997

Functional improvements in ventilatory mechanics after lung volume reduction surgery for homogeneous emphysema.

OBJECTIVE: Between September 1994 and August 1996 Lung Volume Reduction Surgery (LVRS) was performed through median sternotomy, videoendoscopically or by thoracotomy in 54 consecutive patients (age 34-69 years, mean 48 years). METHODS: The areas with the most destroyed lung parenchyma were resected by means of linear stapling devices. A total of 5 patients died postoperatively due to aspiration pneumonia, multiorgan failure and acute hepatic failure respectively. A marked functional improvement and increase in quality of life was observed in the remaining patients. RESULTS: Residual volume decreased from 317.0 +/- 12.4% of predicted (%p) preoperatively to 226.2 +/- 8.8%p within the first month (P = 0.0001). FeV1 significantly increased from 23.7 +/- 1.3%p preoperatively to 36.3 +/- 4.1%p during the first 6 months postoperatively (P = 0.0016). Radiological signs of hyperinflation and distention of the thorax preoperatively improved to a more dome shaped diaphragm and narrowed intercostal spaces. These morphologic changes resulted in better ventilatory muscle function. The intrinsic PEEP significantly decreased from 5.92 +/- 0.64 cm H2O preoperatively to 1.70 +/- 0.25 cm H2O postoperatively (P = 0.0001). The work of breathing decreased from 1.58 +/- 0.09 J/l preoperatively to 0.99 +/- 0.07 J/l postoperatively (P = 0.0001). CONCLUSIONS: In conclusion, LVRS is an excellent therapeutic option for patients with homogeneous emphysema with additional signs of severe hyperinflation.

Female↗
PubMed1997

Incidence and outcome of major non-pulmonary surgical procedures in lung transplant recipients.

OBJECTIVE: Pulmonary transplant recipients are at high risk from various conditions requiring surgical intervention. As little is known about their exact incidence and course, we examined such procedures in detail. METHODS AND PATIENTS: We have retrospectively analyzed major nonpulmonary surgical procedures performed in 124 consecutive patients who received an isolated lung transplant at the University of Vienna between 1989 and December 1995. Twenty-two patients underwent a total of 28 major interventions (22/124 = 17.7%), resulting in an incidence of one procedure every 5.8 patient years of follow-up. The mean interval between transplantation and intervention was 17.9 months (range 3 days to 62 months) with six interventions being carried out during the first month after transplantation. Fourteen emergency operations were performed, the remaining 14 procedures were carried out electively. Overall, 15 abdominal procedures, four thoracic, four orthopedic, two gynecological, one neurosurgical, one urological and one plastic surgery were performed. RESULTS: There was no intraoperative death. Perioperatively, five surgery related deaths were observed (5/28, related mortality 17.9%) with multiple organ failure as the cause of death in all cases. All of these deaths followed emergency operations (5/14 = 35.7%) and all were observed in patients with septic abdominal complications. In contrast, even very extensive procedures were performed electively without related mortality (0/14, P = 0.02). During the first month after transplantation, major surgery was associated with a 50% (3/6) mortality, for late interventions mortality was 9.1% (2/22; P = 0.047). CONCLUSIONS: Pulmonary transplant recipients showed a high incidence of conditions requiring surgical intervention. As expected, septic complications, especially during the immediate post transplant period, carried a very poor prognosis. However, it was reassuring to observe that even extensive surgical procedures could be performed safely without associated mortality in the elective setting.

Adolescent↗
PubMed1997

Survival after surgical treatment of recurrent pulmonary metastases.

OBJECTIVE: Resection of lung metastases is a generally accepted therapeutic strategy today. This retrospective study was performed in order to estimate the value of an aggressive surgical approach in recurrent metastatic disease of the lung. METHODS: The survival rates of 42 patients undergoing repeated resectional treatment for recurrent lung metastases (group A) were compared to the outcome of a total of 288 patients after a single surgical intervention for lung metastases (group B). Survival rates and the relative effects of the various prognostic factors were calculated according to Kaplan-Maier and Mantel Cox or Wilcoxon test. Histology of the primary tumors in group A consisted of 18 carcinomas, 22 sarcomas and two melanomas, in group B the distribution was 64% carcinoma, 27% sarcoma and 9% melanoma. The mean follow-up period was 88.5 months for group A and 27 months for group B. RESULTS: The overall survival rate for group A was 48% at 5 years and 30% at 10 years, the survival rate for group B was 34% at 5 years. CONCLUSION: Long-term survival rates superior to those after single resectional treatment for lung metastases encourage an aggressive surgical approach for this disease.

Adolescent↗
PubMed1997

Anatomical consideration for an implantable centrifugal biventricular assist system.

A miniaturized pivot bearing-supported centrifugal blood pump (Gyro PI) has been developed as a long-term biventricular assist system (BiVAS). In this study we determined the anatomical configuration of this system using a bovine model. Under general anesthesia, a left lateral thoracotomy was performed to open the chest. Two Gyro PI-601 pumps for left and right assists were placed in the preperitoneal pocket by a subcostal abdominal incision. The left pump could be placed along the dome of the diaphragm just beneath the apex of the left ventricle. The right pump could be placed next to the left pump. The inlet and outlet ports of both pumps penetrated the diaphragm. The inlet port of the left pump, with a length of 55 mm, was inserted directly into the apex of the left ventricle. A woven Dacron graft (150 mm long, 11 mm inner diameter) was placed between the outlet port of the left pump and the descending aorta. As for the right pump, a 100 mm long and 120 degree angled inflow conduit was placed between the inlet port and the right ventricular infundibulum. The outlet port of the right pump was connected to the main trunk of the pulmonary artery using a 90 mm long, 11 mm inner diameter Dacron graft. We could perform biventricular assistance to confirm the anatomical feasibility of the Gyro implantable centrifugal BiVAS.

Animals↗