Biomedical subjects

G Laufer

Publications and source records attributed to G Laufer.

At least 55 records · Page 3Linked to original sources

PubMed2000

First clinical experience with the DeBakey VAD continuous-axial-flow pump for bridge to transplantation.

BACKGROUND: A shortage of donor organs and increased numbers of deaths of patients on the waiting list for cardiac transplantation make mechanical circulatory support for a bridge to transplantation a standard clinical procedure. Continuous-flow rotary blood pumps offer exciting new perspectives. METHODS AND RESULTS: Two male patients (ages 44 and 65 years) suffering from end-stage left heart failure were implanted with a DeBakey VAD axial-flow pump for use as a bridge to transplant. In the initial postoperative period, the mean pump flow was 3.9+/-0.5 L/min, which equals a mean cardiac index (CI) of 2.3+/-0.2 L. min(-1). m(-2). In both patients, the early postoperative phase was characterized by a completely nonpulsatile flow profile. However, with the recovery of heart function 8 to 12 days after implantation, increasing pulse pressures became evident, and net flow rose to 4.5+/-0.6 L/min, causing an increase of mean CI up to 2.7+/-0.2 L. min(-1). m(-2). Patients were mobilized and put through regular physical training. Hemolysis stayed in the physiological range and increased only slightly from 2. 1+/-0.8 mg/dL before surgery to 3.3+/-1.8 mg/dL 6 weeks after implantation. CONCLUSIONS: The first clinical implants of the DeBakey VAD axial-flow pump have demonstrated the device to be a promising measure of bridge-to-transplant mechanical support.

Adult↗

PubMed2000

Pre- and early postoperative risk factors for death after cardiac transplantation: a single center analysis.

Due to the limited number of donor organs, death on the waiting list and waiting time for cardiac transplantation have markedly increased. A pressing need of appropriate selection criteria for patients who would benefit most from transplantation is apparent. The purpose of this study is to identify pre- and early postoperative risk factors that influence long term survival after cardiac transplantation. 702 consecutive patients who underwent cardiac transplantation between 3/1984 and 12/1997 were analyzed retrospectively for the influence of different pre- and early postoperative risk factors on early (30 days) and late death (5 years). Univariate and multivariate regression analysis revealed risk factors for early as well as late death. Predictors of early death were higher preoperative PVR, retransplantation, longer ischemic time, postoperative acute kidney failure and longer intubation time. Risk factors for late death were early transplant era, previous cardiac surgery, patients awaiting transplantation in a hospital, prolonged stay in an intensive care unit, and any rejection during the first month after transplantation. These results demonstrate that pre- and early postoperative risk factors have significant influence on early and long term survival.

Adolescent↗

PubMed2000

[6 years clinical experience with the TEKNA bivalve heart valve prosthesis].

OBJECTIVE: The revised Edwards-Duromedics valve was introduced onto the market in June 1990. In September 1993, the producer changed the name of the valve to TEKNA, which is a low profile, bileaflet, mechanical prosthesis with a self-irrigating hinge mechanism. The results of a prospective follow-up study after valve replacement with this prosthesis are presented. METHODS: From November 1990 to December 1996, 173 TEKNA prostheses were implanted in 161 patients (73 men, 88 women), either in the aortic (AVR; 48.4%), mitral (MVR; 44.1%), or aortic and mitral positions (DVR; 7.5%). Patient ages ranged from 17 to 83 years (mean age 59.2 +/- 8.7 years). Follow-up was 97.5% complete, comprising 433.15 patient-years for a mean follow-up of 34.8 +/- 23 months. RESULTS: Overall operative (30-day) mortality was 4.97%. Fifteen patients died in the late period, corresponding to a linearized late mortality rate of 3.5%/pt-yr. Actuarial survival at six years was 75.3% +/- 6.2% overall. The actuarial freedom from complications was calculated as follows (linearized rates in parentheses): valve-related mortality 91.3% +/- 5.1% (0.92%/pt-yr); thromboembolism 94.2% +/- 2.5% (1.62%/pt-yr); valve thrombosis 98.6 +/- 1.0% (0.46%/pt-yr); bleeding events 85.9% +/- 4.7% (2.77%/pt-yr); prosthetic valve endocarditis 98.6 +/- 0.9% (0.46%/pt-yr); nonstructural dysfunction 93.2 +/- 3.2% (1.38%/pt-yr); reoperation 87.1 +/- 5.3% (2.08%/pt-yr). Functional class according to NYHA was improved from preoperatively 72.05% in III or IV to 6-year postoperative 94.2% in I or II. CONCLUSION: The clinical performance of the TEKNA valve is quite satisfactory, with low incidence of valve-related complications. No structural deterioration has been observed. Further, the patients physical ability and quality of life were significantly improved.

Adolescent↗

PubMed2000

Efficacy of two methods for reducing postbypass afterdrop.

BACKGROUND: Afterdrop, defined as the precipitous reduction in core temperature after cardiopulmonary bypass, results from redistribution of body heat to inadequately warmed peripheral tissues. The authors tested two methods of ameliorating afterdrop: (1) forced-air warming of peripheral tissues and (2) nitroprusside-induced vasodilation. METHODS: Patients were cooled during cardiopulmonary bypass to approximately 32 degrees C and subsequently rewarmed to a nasopharyngeal temperature near 37 degrees C and a rectal temperature near 36 degrees C. Patients in the forced-air protocol (n = 20) were assigned randomly to forced-air warming or passive insulation on the legs. Active heating started with rewarming while undergoing bypass and was continued for the remainder of surgery. Patients in the nitroprusside protocol (n = 30) were assigned randomly to either a control group or sodium nitroprusside administration. Pump flow during rewarming was maintained at 2.5 l x m(-2) x min(-1) in the control patients and at 3.0 l x m(-2) x min(-1) in those assigned to sodium nitroprusside. Sodium nitroprusside was titrated to maintain a mean arterial pressure near 60 mm Hg. In all cases, a nasopharyngeal probe evaluated core (trunk and head) temperature and heat content. Peripheral compartment (arm and leg) temperature and heat content were estimated using fourth-order regressions and integration over volume from 18 intramuscular needle thermocouples, nine skin temperatures, and "deep" hand and foot temperature. RESULTS: In patients warmed with forced air, peripheral tissue temperature was higher at the end of warming and remained higher until the end of surgery. The core temperature afterdrop was reduced from 1.2+/-0.2 degrees C to 0.5+/-0.2 degrees C by forced-air warming. The duration of afterdrop also was reduced, from 50+/-11 to 27+/-14 min. In the nitroprusside group, a rectal temperature of 36 degrees C was reached after 30+/-7 min of rewarming. This was only slightly faster than the 40+/-13 min necessary in the control group. The afterdrop was 0.8+/-0.3 degrees C with nitroprusside and lasted 34+/-10 min which was similar to the 1.1+/-0.3 degrees C afterdrop that lasted 44+/-13 min in the control group. CONCLUSIONS: Cutaneous warming reduced the core temperature afterdrop by 60%. However, heat-balance data indicate that this reduction resulted primarily because forced-air heating prevented the typical decrease in body heat content after discontinuation of bypass, rather than by reducing redistribution. Nitroprusside administration slightly increased peripheral tissue temperature and heat content at the end of rewarming. However, the core-to-peripheral temperature gradient was low in both groups. Consequently, there was little redistribution in either case.

Adult↗

PubMed2000

Adhesion molecule behavior during rejection and infection episodes after heart transplantation.

In cardiac transplant recipients the release of soluble cellular adhesion molecules intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and E-Selectin into serum is pronounced during immune activation. It is uncertain whether there is a specific pattern of release during infection or cardiac allograft rejection. In a prospective study, 30 consecutive cardiac allograft recipients were followed for a median period of 11.4 months (range 1-34). Soluble ICAM-1 (sICAM-1), soluble VCAM-1 (sVCAM-1) and soluble E-Selectin (sE-Selectin) were measured in addition to acute phase proteins (C-reactive protein, alpha1-antitrypsin), complement factors (C3, C4) and beta2-microglobulin. The measured serum levels were correlated with the clinical status of the transplant recipient: 1) uneventful clinical status; 2) asymptomatic infection; 3) symptomatic infection and 4) rejection. Forty age-matched healthy subjects served as controls. Six days before biopsy-proven cardiac allograft rejection sICAM-1-release started to increase (p < 0.05) as compared to uneventful clinical status. The peak concentration of sICAM-1 was measured three days before rejection. On the day of rejection, serum concentrations of sICAM-1 (p < 0.001) and sVCAM-1 (p < 0.05) were increased, whereas sE-Selectin was not markedly elevated. In symptomatic infections, the serum concentrations of sICAM-1 (p < 0.001) and sVCAM-1 (p < 0.05) were elevated at the day of diagnosis and both parameters reached peak levels three days after onset of chemotherapy. In multivariate analysis soluble adhesion molecules only weakly discriminated between rejection and infection (sensitivity: 13%, specificity: 95%). Although, in combination with routine blood parameters the discriminatory power could be improved (sensitivity: 85%, specificity: 85%) the clinical utility of these markers in non-invasive monitoring is limited.

Adult↗

PubMed2000

Examination of hemolytic potential with the On-X(R) prosthetic heart valve.

BACKGROUND AND AIM OF THE STUDY: Mechanical valves are known to produce chronic, subclinical hemolysis in most patients. Generally, haptoglobin is reduced to below normal in most patients, while lactate dehydrogenase (LDH) is increased to as much as 200% above the upper normal, sometimes resulting in anemia. The study was designed to investigate the clinical hemolysis of the On-X(R) prosthetic heart valve in a multicenter experience with a standard protocol and a single clinical laboratory. METHODS: Between September 1996 and August 1998, 248 patients underwent isolated valve replacement at 10 European centers. Blood samples were collected from these preoperatively and at 3-6 months and one year postoperatively. All samples were analyzed at a central laboratory, thus assuring poolability of the data. In total, 151 patients were tested at 3-6 months, and 62 at one year. Blood parameters measured were LDH, haptoglobin, hematocrit, total hemoglobin, red cell count and reticulocyte count. Paired analysis was used to compare preoperative baseline values with 3-6-month and one-year values. Data were analyzed with regard to both valve position and size. RESULTS: At 3-6 months and one year after surgery, average values for hematocrit, hemoglobin, red cell count and reticulocyte count were all near the center of the normal range, regardless of valve position or size. Statistically significant increases in red cell count and decreases in reticulocyte count occurred after both aortic valve replacement (AVR) and mitral valve replacement (MVR). These changes were of no clinical importance, but indicate that anemia has not occurred in these patients. At 3-6 months, haptoglobin was reduced to below normal in 86% of both AVR and MVR patients; this also occurred after one year and was statistically significant. Postoperatively, the mean LDH value in AVR was 228 U/l (91% of upper normal, 250 U/l) at 3-6 months, and 246 U/l (98% of upper normal) at one year. In MVR, these LDH values were 271 U/l (108% of upper normal) and 265 U/l (106% of upper normal). CONCLUSIONS: These results indicate that the On-X valve causes lower levels of chronic hemolysis in the immediate postoperative period and up to one year after surgery, especially when compared with reports of LDH elevations up to 200% of upper normal. Hemolytic anemia has not occurred in this patient population.

Aortic Valve↗

PubMed2000

Does the Ross operation fulfil the objective performance criteria established for new prosthetic heart valves?

BACKGROUND AND AIM OF THE STUDY: Objective Performance Criteria (OPC) were established to compare a new heart valve prosthesis with fixed standards of linearized complication rates for morbid events: thromboembolism, thrombosis, hemorrhage, leakage and endocarditis. Although the pulmonary autograft operation provides optimal hemodynamic performances, the morbidity of both the autograft and homograft remain topics of controversy. METHODS: Valve-related morbid events and echocardiography in 109 patients who have undergone the Ross operation since 1991 were evaluated at annual follow up examination (mean 2.8 years; range: 1 month to 8 years). Linearized rates (number of events per 100 years patient exposure) were calculated to establish the safety and efficacy of this operation (288.7 years cumulative patient-years). RESULTS: Three patients died perioperatively (2.8%); two patients were reoperated due to autograft incompetence (1.8%, both valve repairs). No patient is currently on anticoagulation therapy, and no events of thromboembolism, valve thrombosis or bleeding were observed during follow up. Two patients had homograft endocarditis but were asymptomatic with moderate incompetence at the last follow up examination. There was no significant increase in aortic incompetence (AI) or pulmonary incompetence (PI) between discharge and follow up (AI, 0.4 +/- 0.5 versus 0.6 +/- 0.6; PI, 0.2 +/- 0.4 versus 0.4 +/- 0.6). In comparing the OPC (events per patient-year) for the Ross operation with those for tissue and mechanical valves, the results were: thromboembolism 0% (tissue 2.5%, mechanical 3%), valve thrombosis 0% (0.2% and 0.8%), all bleeding 0% (1.4% and 3.5%), major bleeding 0% (0.9% and 1.5%), all leakage 0.7% (1.2% and 1.2%), major leakage 0.7% (1.2% and 1.2%) and endocarditis 0.7% (1.2% and 1.2%). CONCLUSION: The pulmonary autograft procedure provides optimal hemodynamics and echocardiographic performance, and low valve-related complication rates; thus, the OPC for tissue and mechanical heart valve prostheses can be fulfilled by this technically demanding operation. These results confirm that the autograft is an ideal aortic valve replacement device.

Adolescent↗

PubMed2000

Mid-term follow up of mitral valve reconstruction due to active infective endocarditis.

BACKGROUND AND AIM OF THE STUDY: Mitral valve reconstruction in patients with acute endocarditis (AE) is a challenging operation which prompts the surgeon into immediate action. This report summarizes the mid-term results of 22 patients who required mitral valve reconstruction due to AE. METHODS: Mean patient age was 46 years (range: 20-79 years); mean follow up was 46 months (range: 1-90 months). Preoperatively, >70% of patients had severe mitral regurgitation and were in NYHA functional class III. Surgical techniques used were annuloplasty (n = 16; 10 with Carpentier ring, five Wooler-Kay and one Frater); suture closure of the perforation (n = 1), patch closure of the perforation (n = 5), leaflet resection with primary closure (n = 2), leaflet resection with patch closure (n = 8), and chordal transfer (n = 3). Additional surgery included CABG (n = 3) and De Vega plasty (n = 4). Aortic valve replacement or reconstruction (n = 9) included one mechanical valve, one bioprosthesis, one reconstruction and six homografts. Patients were followed up annually in our outpatient department and/or by questionnaires. RESULTS: Two patients died perioperatively due to either low output syndrome or uncontrolled sepsis. There were three reoperations; two of these were successful, and one patient subsequently died. In addition, one patient died six years after operation due to prostatic cancer, and one seven years later due to progressive heart failure. At the last follow up, 15 patients were in NYHA class I (68%) and five in class II (23%); no or only mild mitral insufficiency was seen on transthoracic echocardiography (91%). The estimated survival rate at 60 months was 87 +/- 12.7%, and 12 patients were followed up for >60 months. No incidence of recurrent valve infection occurred. CONCLUSION: Mitral valve reconstruction in patients with AE shows a low incidence of valve-related complications with promising postoperative functional results and mid-term survival. On this basis, mitral valve reconstruction for mitral insufficiency secondary to AE may be recommended as a valve salvage treatment, when it is technically possible.

Endocarditis, Bacterial↗

PubMed1999

Safety, tolerability and efficacy of cyclosporine microemulsion in heart transplant recipients: a randomized, multicenter, double-blind comparison with the oil based formulation of cyclosporine--results at six months after transplantation.

BACKGROUND: The introduction of cyclosporine has resulted in significant improvement in the survival of cardiac allograft recipients due to decreased mortality from infection and rejection. The original oil-based cyclosporine formulation exhibits variable and unpredictable bioavailability that correlates with an increased incidence of acute and chronic rejection in those patients in whom this is most pronounced. The primary objectives of this prospective, multicenter, randomized, double-blind study in cardiac transplant patients were: to compare the efficacy of cyclosporine microemulsion (CsA-NL) with oil-based cyclosporine (CsA-SM) as measured by cardiac allograft and recipient survival and the incidence and severity of acute rejection episodes; and to assess the safety and tolerability of CsA-NL compared with CsA-SM in this population. This report represents the analysis of results 6 months after transplantation. METHODS: A total of 380 patients undergoing their first cardiac transplant at 24 centers in the United States, Canada, and Europe were enrolled in this double-blind, randomized trial examining the safety and efficacy of CsA-NL versus CsA-SM. Rejection was diagnosed using endomyocardial biopsy and were graded according to standardized criteria of the International Society of Heart and Lung Transplantation (ISHLT). Clinical parameters were monitored during the study. Survival and freedom from were used for analysis as was Fisher's exact test for comparisons between groups. RESULTS: At 6 months after transplantation, allograft and patient survival were the same for both groups. The frequency of ISHLT grade 3A or greater episodes in the two groups was identical. Fewer CsA-NL patients (5.9%) required antilymphocyte antibody (ATG or OKT-3) therapy for rejection compared with the CsA-SM-treated patients (14.1%, P=0.01). Females with ISHLT rejection grade > or = 3A treated with CsA-NL had a 46% lower incidence of rejection compared with the CsA-SM-treated group (31.3% vs. 57.6%, P=0.032). Fewer infections were seen in the CsA-NL. With the exception of baseline and 1 week posttransplant creatinines which were higher in the CsA-NL group, the overall creatinine was not significantly different between the two groups. CONCLUSIONS: This multicenter, randomized study of cardiac transplant recipients documented less severe rejection (in particular those requiring antibody therapy) and a lower incidence of infection in CsA-NL-treated patients. Results from the female subgroup analysis suggest that the improved bioavailability of CsA-NL might reduce the frequency of rejection episodes in female patients. The use of CsA-NL was not associated with an increased risk of adverse events.

Adolescent↗

PubMed1999

[The DeBakey VAD axial flow pump: first clinical experience with a new generation of implantable, nonpulsatile blood pumps for long-term support prior to transplantation].

Because of the high frequency of acute hemodynamic deterioration in patients awaiting cardiac transplantation, mechanical techniques of circulatory support to bridge the period until transplantation have become a standard clinical procedure. Continuous-flow rotary blood pumps offer exciting new perspectives in terms of ventricular assistance and/or as a total cardiac substitute. A DeBakey VAD axial flow pump was implanted in two male patients (aged 44 and 65 years, respectively) suffering from end-stage left heart failure. In the initial postoperative period the mean flow rate of the pump was 3.9 +/- 0.5 l/min. In both patients, the early postoperative phase was characterised by a completely non-pulsatile flow profile. Two weeks after implantation and partial recovery of the natural left ventricle, increasing pulse pressures became evident and net flow increased to 4.5 +/- 0.6 l/min. Patients were mobilised and made to under-go regular physical training. Hemolysis produced by the pump was low while free haemoglobin stayed in physiological ranges, increasing only slightly from 2.1 +/- 0.8 mg/dl preoperatively to 3.0 +/- 1.5 mg/dl ten weeks after implantation. One patient was successfully transplanted on day 74 after implantation of the DeBakey VAD while the second patient is, after 110 days of pumping, still waiting for transplantation. This first experience concerning clinical implantation of the DeBakey VAD axial flow pump showed that the device is promising as a means of providing mechanical support to bridge the period until cardiac transplantation.

Adult↗

PubMed1999

Local anaesthesia versus general anaesthesia for cardioverter-defibrillator implantation.

AIMS: Cardioverter-defibrillators are conventionally implanted under general anaesthesia. However, implantation under conscious sedation is being increasingly used. It has been shown that cardioverter-defibrillators can be implanted in a more pacemaker-like approach: under local anaesthesia for the surgical procedure, and with mild sedation for defibrillation threshold testing only. The aim of the present study was to compare local and general anaesthesia in defibrillation threshold testing and implantation of cardioverter-defibrillators. METHODS AND RESULTS: Forty patients were assigned to two groups: in the first 20 consecutive patients the cardioverter-defibrillator was implanted under general anaesthesia (GA), and in the subsequent 20 patients under local anaesthesia (LA). There was no significant difference between the two groups in regard of age, body weight, underlying disease, left ventricular ejection fraction, and NYHA classification. The defibrillation threshold was 13.7 +/- 5.5 J under local anaesthesia versus 10.7 +/- 4.7 J under general anaesthesia (n.s.). For defibrillation threshold testing 7.9 +/- 3.6 shocks had to be applied in patients under general anaesthesia versus 6.2 +/- 1.3 shocks under local anaesthesia (n.s.). Mean heart rate, arterial oxygen saturation and mean arterial blood pressure remained stable throughout defibrillation threshold testing, irrespective of the type of anaesthesia used. The duration of the surgical procedure was 62 +/- 16 min under GA and 60 +/- 14 min under LA (n.s.), however, the entire implantation procedure was significantly longer in patients under general anaesthesia than in those under local anaesthesia (124 +/- 24 min and 97 +/- 22 min, respectively, p < 0.005). There were no complications in either group and the procedure was well tolerated. With the use of local anaesthesia the cost of anaesthesia were reduced by 72%. CONCLUSION: Local anaesthesia in combination with mild sedation is as safe and well tolerated as general anaesthesia in cardioverter-defibrillator implantation. Lidocaine used for local anaesthesia does not adversely affect the defibrillation threshold. Device implantation in a pacemaker-like approach results in a significant reduction in total procedure time and costs, and facilitates scheduling of the procedure.

Anesthesia, General↗

PubMed1999

Cardiac transplantation and simultaneous surgical repair of an aortic aneurysm.

Simultaneous cardiac transplantation and surgical repair of an aortic aneurysm has not been reported previously. At our institution, a 59-year-old patient with an aneurysm of the ascending aorta and aortic arch required orthotopic cardiac transplantation for end-stage cardiomyopathy. He underwent successful surgical replacement of his ascending aorta and transverse arch (in circulatory arrest and deep hypothermia) at the time of heart transplantation.

Anastomosis, Surgical↗

PubMed1999

Impact of retrograde cerebral perfusion on aortic arch aneurysm repair.

OBJECTIVE: Protection of the brain is a primary concern in aortic arch surgery. Retrograde cerebral perfusion is a relatively new technique used for cerebral protection during profound hypothermic circulatory arrest. This study was designed to compare, retrospectively, the outcome of 109 patients undergoing aortic arch operation with and without the use of retrograde cerebral perfusion. METHODS: Fifty-five patients had profound hypothermic circulatory arrest alone, and 54 patients had supplemental cerebral protection with retrograde cerebral perfusion. Mean age was 61 +/- 13 years and 58 +/- 14 years, respectively (mean +/- standard deviation). Twenty-two preoperative and intraoperative characteristics, including age, sex, acuity, presence of aortic dissection, and aneurysm rupture, were similar in the 2 groups (P >.05). RESULTS: Mean circulatory arrest times (in minutes) were 30 +/- 19 in the group without retrograde cerebral perfusion and 33 +/- 19 in the group with retrograde cerebral perfusion, respectively. chi(2) Analysis revealed that patients operated on with the use of retrograde cerebral perfusion had significantly lower hospital mortality (15% vs 31%; P =.04) and in-hospital permanent neurologic complications (9% vs 27%; P =.01). Retrograde cerebral perfusion failed to reduce the prevalence of temporary neurologic dysfunction (17% vs 18%; P =.9). Stepwise multiple logistic regression revealed that extracorporeal circulation time, age, and lack of retrograde cerebral perfusion were statistically significant independent risk factors for hospital mortality. The same analysis revealed that lack of retrograde cerebral perfusion was the only significant independent risk factor for permanent neurologic dysfunction. CONCLUSION: Retrograde cerebral perfusion decreased the prevalence of permanent neurologic complications and the hospital mortality in patients undergoing aortic arch operations.

Adult↗

PubMed1999