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Biomedical subjects

B Reichart

Publications and source records attributed to B Reichart.

At least 19 recordsLinked to original sources
PubMed1998

Endothelium-dependent microvascular vasomotion and its correlation with vasoactive mediators early after cardiac transplantation in humans.

Endothelial dysfunction precedes and predicts transplant vasculopathy. We investigated the relationship between endothelial dysfunction and the vasoactive mediators nitric oxide and endothelin, 33.7 +/- 2.0 days after heart transplantation. Coronary flow was measured in 18 patients to determine the endothelial microvascular vasomotor response to acetylcholine. Endomyocardial biopsies were taken to determine the levels of gene expression of isozymes of endothelin and nitric oxide synthases (NOS). Blood samples from the coronary sinus and aorta were withdrawn for measurement of endothelin, nitrite and cytokines. Five patients (30%) showed an impaired coronary flow reserve response to acetylcholine, significantly higher inducible NOS gene expression and significant transcardiac nitrite production. Plasma nitrite correlated with tumour necrosis factor-alpha levels in coronary sinus and a transcardiac net extraction of endothelin was noted in all patients. In conclusion, 30% of patients develop endothelial dysfunction early after heart transplantation; this correlates with the expression and activation of vasoactive and immunomodulatory mediators, which may predict the development of transplant vasculopathy.

Endothelin-1↗
PubMed1998

[Minimally invasive heart surgery--a fad or a clinically recognized therapy method?].

Within the last 5 years new less invasive surgical techniques have been developed in the field of cardiac surgery. This new field named "minimally invasive cardiac surgery" can be subdivided into techniques which do not require cardiopulmonary bypass and are used mainly for coronary artery surgery (called minimally invasive direct coronary artery surgery, MIDCAB technique). This MIDCAB procedure can be done through a small left anterior thoracotomy or a sternotomy. In addition there are other methods which allow the performance of complex cardiac surgery through small accesses in combination with the use of an endovascular CPB system and internal aortic clamping to achieve cardioplegic arrest (so-called Port-Access method). Also for valvular surgery, new surgical techniques were developed allowing access to mitral and aortic valves through limited incisions. In addition, new less invasive techniques were developed for congenital heart surgery. This article will describe the various surgical techniques and define the indications for minimally invasive cardiac surgery.

Endoscopes↗
PubMed1998

Minimally invasive coronary artery bypass grafting: port-access approach versus off-pump techniques.

BACKGROUND: Within the past 5 years several surgical techniques have been developed for less invasive surgical treatment of coronary artery disease. The aim of this study was to define specific indications for the various minimally invasive coronary artery surgical procedures. METHODS: Minimally invasive direct coronary artery bypass grafting through a minithoracotomy was performed in 67 patients. The left internal mammary artery was anastomosed on the beating heart with the use of a pressure or suction stabilizer without the use of extracorporeal circulation. In 58 other patients with multivessel disease, the off-pump coronary artery bypass grafting technique through a sternotomy was applied with a left internal mammary artery to left anterior descending artery and additional vein grafts without extracorporeal circulation. In a third group, Port-Access (Heartport Inc, Redwood City, CA) coronary artery bypass grafting was performed through a left minithoracotomy with the use of an endovascular extracorporeal circulation system and cardioplegic arrest. Angiographic follow-up was complete in 64% of the patients. RESULTS: There was minimal perioperative or postoperative mortality (0.5%). The medium surgical procedure time for all minimally invasive and off-pump procedures was 2.5 hours; it was 4.5 hours for Port-Access procedures. The median postoperative intensive care unit stay was 1.0 days, and the median hospitalization was 5.0 days. Overall graft patency was 97.3%; in 8 patients (4.1%) a stenosis either at or distal to the graft anastomosis was dilated with coronary angioplasty. CONCLUSIONS: For single-vessel disease of the left anterior descending artery, the minimally invasive coronary artery bypass grafting procedure can be performed safely without the use of extracorporeal circulation. In case of hemodynamic instability or anatomic variation, the Port-Access procedure can be applied without additional necessity for sternotomy. For multivessel disease, the off-pump bypass grafting procedure with sternotomy can be recommended depending on the coronary arteries involved. In case of necessary grafts to the lateral marginal or circumflex branches, Port-Access grafting can be recommended and may play an important role in the future for the development of fully endoscopic robot-assisted coronary artery bypass grafting.

Adult↗
PubMed1998

Nitric oxide and endothelin in the development of cardiac allograft vasculopathy. Potential targets for therapeutic interventions.

Extensive research has been carried out in recent years to discover the potential risk factors contributing to cardiac allograft atherogenesis. Injury to endothelial cells has been regarded as an important early mechanism in the development of transplant atherosclerosis; it leads to the manifestation of epicardial and microvascular endothelial dysfunction and development of intimal hyperplasia. Moreover, continuous minor endothelial cell damage contributes to endothelial dysfunction which reflects one of the first measurable steps in the cascade of atherogenesis without macroscopic evidence of vascular lesions. The discovery of two important vasoactive substances nitric oxide (NO) and endothelin (ET) has brought new insights but also new unsolved questions regarding the mechanisms leading to atherosclerosis. To date it is known that both substances play a major role in both prevention and development of atherosclerosis. NO appears to be protective in low concentrations by inhibiting leukocyte and platelet activation/adherence and smooth muscle cell proliferation. Impaired endothelial NO production, as one cause of endothelial dysfunction may occur in early stages of atherosclerosis before macroscopic lesions are evident. In addition, increased endothelin release also results in endothelial dysfunction by inducing vasoconstriction; it promotes vascular lesion formation due to endothelial- and vascular smooth muscle cell proliferation. Direct and indirect manipulation of both the NO and ET signal transduction systems may provide novel preventive and therapeutic approaches for limiting transplant atherogenesis and to treat native atherosclerosis. This review summarizes important experimental and clinical evidence which points to nitric oxide and endothelin as potential therapeutic targets in the process of cardiac allograft vasculopathy.

Animals↗
PubMed1998

Long-term prognosis of surgically-treated aortic aneurysms and dissections in patients with and without Marfan syndrome.

OBJECTIVE: Aortic aneurysms and dissections are the leading causes of premature death in Marfan syndrome (MfS). This study aims to compare long-term results of surgically treated aortic aneurysms and dissections in patients with and without MfS in respect to early and late prognosis. METHODS: From March 1975 to August 1994, 33 patients with classic MfS (group A, age 34.2 +/- 9 years) and 298 patients with non-fibrillinopathic aortic disease (group B, age 54 +/- 13 years) underwent aortic surgery. Acute dissections occurred in 57.6 (A) versus 37.9% (B). A total of 54.6% of patients in group A were treated with a composite graft versus 16.4% in B. The aortic arch and the descending aorta was replaced in 30.4% of MfS patients and 24.9% of patients without MfS. RESULTS: We observed 7 (25.0%, A) versus 35 (14.2%, B) late deaths among the 28 (A) versus 247 (B) early survivors. In 5 patients (17.9%) of A and 8 patients (3.2%) of B, late death was caused by redissection or recurrent aneurysm (P < 0.001). Long-term survival after 5, 10 and 15 years in group A was 82 +/- 7, 60 +/- 11 and 30 +/- 22%, and 75 +/- 3, 69 +/- 3 and 64 +/- 4% in group B. A total of 22 reoperations were performed in 11 MfS patients, 17 reoperations were due to recurrent aortic diseases. Three of the 8 patients underwent reoperation after Wheat procedure because of sinus valsalva aneurysm. None of the patients with composite graft replacement needed reoperation in this segment, but 3 patients suffered from redissection at the proximal aortic arch. In group B, reoperations were significantly less frequent (10.7%) compared to MfS patients (66.7%; P < 0.001). CONCLUSIONS: Surgical treatment of aortic disease in MfS patients is associated with a high risk of redissection and recurrent aneurysm. If the ascending aorta needs to be replaced, we recommend the composite graft technique and a more aggressive approach to reduce the frequency of distal reoperations. In order to reduce the high reoperation rate in MfS patients, frequent clinical follow-up may contribute to improve life expectancy in MfS patients.

Adult↗
PubMed1998

Central venous pressure, pulmonary capillary wedge pressure and intrathoracic blood volumes as preload indicators in cardiac surgery patients.

OBJECTIVE: Monitoring of cardiac preload is mainly performed by measurement of central venous and pulmonary capillary wedge pressure in combination with assessment of cardiac output, applying the pulmonary arterial thermal dilution technique. However, the filling pressures are negatively influenced by mechanical ventilation and the pulmonary artery catheter is criticized because of its inherent risks. Measurement of right atria, right ventricular, global end diastolic and intrathoracic blood volume index by arterial thermal dye dilution utilizing the COLD-system may represent an alternative. METHODS: In 30 CABG patients with an uncomplicated postoperative course the mentioned parameters were measured 1, 3, 6, 12 and 24 h postoperatively to prove their qualification as preload indicators: As patients received no inotropic support, changes of cardiac index and stroke volume index must correlate to changes of presumably preload indicating parameters. RESULTS: When arterial and pulmonary arterial thermal dilution were compared, no differences were found; the correlation coefficient being 0.96, the bias 0.16 l/min per m2 (2.4%) and coefficients of variation did not exceed 7%. Changes of central venous pressure, capillary wedge pressure, right atrial end diastolic volume index and right ventricular end diastolic volume index did not correlate at all to changes of cardiac and stroke volume index (coefficients ranged from -0.01 to 0.28). In contrast, intrathoracic and global end diastolic blood volume indices with coefficients from 0.76 to 0.87, did show a good correlation to cardiac and stroke volume index. CONCLUSION: Central venous pressure, capillary wedge pressure, right atrial and right ventricular end diastolic volumes are no suitable preload parameters in cardiac surgery intensive care, compared to intrathoracic and global end diastolic blood volumes. The latter show a higher clinical value and can be obtained by less invasive methods, as no pulmonary artery catheter is required.

Adult↗
PubMed1998

Bicarbon valve -- European multicenter clinical evaluation.

OBJECTIVE: Fifteen collaborating centers in eight countries present their pooled experience with the new Bicarbon bileaflet valve. METHODS: Between 4/90 and 4/96, 1351 patients, 806 males and 545 females, aged 10 to 83, mean 58.4 +/- 12.4, underwent valve implantation. OPERATIONS: aortic valve replacement (AVR), 726; mitral valve replacement (MVR), 475; double valve replacement (DVR), 150. Additional procedures: CABG, 211; TV repair, 64; other, 152. RESULTS: Mortality: 67 early (seven valve related) and 56 late (40 valve related). Valve thrombosis: six obstructive, three non-obstructive; embolism: nine major cerebral, 37 other. Major bleeding: 29. Hemolysis: two clinically significant. Non-structural dysfunction: 24 paravalvular leaks, one leaflet interference. No structural failure! Endocarditis: 24. Reoperation 48: 22 non-structural dysfunctions, 14 endocarditis, seven thrombosis and embolism, five other. Estimated 5-year freedom from valve-related deaths is 97.2% for AVR and 92.4% for MVR; 4-year freedom from valve related deaths for DVR is 90.5%. Mean calculated NYHA improvement is 1.24. CONCLUSIONS: The Bicarbon mechanical prosthesis is well designed, durable, has good hemodynamic features and an acceptably low incidence of complications.

Adolescent↗
PubMed1998

Continuous, less invasive, hemodynamic monitoring in intensive care after cardiac surgery.

A pulse-contour-based method for continuous measurement of cardiac output (CO) and systemic vascular resistance (SVR) was tested and arterial thermodilution, used for calibration, was compared to pulmonary artery thermodilution. In 30 patients CO and SVR were measured by pulse contour analysis (COpc, SVRpc) 270 times in 24 h and compared to arterial (COart, SVRart) and pulmonary arterial (COpa, SVRpa) thermodilution measurements. The mean difference between COpa and COart was 0.26 L/min (3.6%) with a standard deviation (SD) of 0.7 L/min, the correlation coefficient was 0.96, and the coefficient of variation was 5.0% and 5.9% respectively. COpc did differ from COpa by 0.11 L/min (1.5%, SD = 0.6 L/min) and from COart by 0.15 L/min (2.1%, SD = 0.7 L/min). Correlation of COpc with COpa was 0.91, correlation of COpc with COart was 0.90. SVRpc did correlate with SVRpa, a coefficient of 0.94, and with SVRart, a coefficient of 0.92. Mean COpc and SVRpc did not differ significantly from COpa or COart and SVRpa or SVRart during the 24 h study period. It is concluded that COart correlates well with COpa and can be used to calibrate COpc. COpc and SVRpc agree with thermodilution-based CO and SVR without recalibration for 24 hours.

Adult↗
PubMed1998

Reproducibility of double indicator dilution measurements of intrathoracic blood volume compartments, extravascular lung water, and liver function.

STUDY OBJECTIVE: Arterial thermal dye dilution (TDDart) with the COLD system (Munich, Germany) allows measurement of cardiac index (CI), partial blood volumes, lung water, and liver function. The aim of the study was to determine agreement of TDDart measurements with pulmonary artery thermal dilution measurements (TDpa) and to assess the reproducibility of TDDart parameters. DESIGN: Prospective study. SETTING: ICU of a university hospital department of cardiac surgery. PATIENTS: Thirty consecutive patients after coronary artery bypass grafting. MEASUREMENTS AND RESULTS: Triplicate measurements of TDDart parameters were performed 1, 3, 6, 12, and 24 h postoperatively and coefficients of variation (CVs) were computed. At the 3-h point, additional fivefold TDDart measurements were done and compared with TDpa measurements. The coefficient of correlation for CI from TDDart vs TDpa was 0.96 (p<0.001), and the mean difference was 0.16 L/min/m2 (2.4%). The CVs of the TDDart and TDpa CI measurement were 7.2% and 5.9%; the CVs of other TDDart parameters were 4.6% (cardiac function index), 8.3% (global end-diastolic volume), 7.0% (intrathoracic blood volume), 7.6% (total blood volume), 7.4% (right ventricular end-diastolic volume), 7.4% (right heart end-diastolic volume), 11.3% (left heart end-diastolic volume [LHEDV]), 12.0% (right to left heart volume proportion [R/LHV]), 8.8% (pulmonary blood volume), 10.8% (extravascular lung water), 16.4% (plasma disappearance rate of dye), and 19.8% (dye clearance). The CV did not depend on Glasgow coma scale or on body temperature. CONCLUSION: The CVs of LHEDV and R/LHV are influenced by asynchronous TDDart and TDpa variation. The CVs of plasma disappearance and dye clearance are increased as the half-life of the dye is longer than the measurement sequence. All other parameters derived from TDDart and TDpa show a clinically sufficient reproducibility.

Adult↗
PubMed1998

Detecting acute graft rejection in patients after orthotopic heart transplantation: analysis of heart rate variability in the frequency domain.

BACKGROUND: Acute transplant rejection is a major complication after heart transplantation. To treat patients with rejection, early detection is necessary before fatal heart dysfunction. Because of its invasive aspect, endomyocardial biopsy is limited with respect to its frequency and complication rate. Little work has been done so far to develop noninvasive methods for detecting rejection, and, hence, investigation for such methods would seem to be of considerable value. METHODS: After routine endomyocardial biopsy in 117 heart transplant recipients (age 49 +/- 13 years time after transplantation 6 to 48 months), electrocardiography results were recorded with the patient in a supine position at a controlled respiratory rate (0.25 Hz) over 10 minutes. Patients with an artificial pacemaker or severe arrhythmia were excluded. On the basis of endomyocardial biopsy reports, two groups of patients were defined: patients without rejection (AR0, n = 73) and patients with severe rejection (AR1b to AR4, n = 32). The spectra of R-wave to R-wave intervals were calculated, and different spectral components were evaluated: low frequency (LF, 0.05 to 0.18 Hz), high frequency (HF, 0.18 to 0.5 Hz), LF + HF, LF + HF minus the respiratory peak (RP) (LF + HF - RP), and the total power (0 to 0.5 Hz). RESULTS: All frequency domain parameters except HF were significantly higher in patients with severe rejection than in patients without rejection. By means of the calculation of receiver operating characteristic curves, LF + HF - RP was the most reliable frequency domain parameter for the detection of severe rejection. Setting its threshold value to 5 msec2, 77% sensitivity, and 76% specificity could be achieved. CONCLUSIONS: Spectral analysis of heart rate variability may be used as a noninvasive tool to detect severe rejection episodes.

Adolescent↗
PubMed1998

European Multicenter Tacrolimus (FK506) Heart Pilot Study: one-year results--European Tacrolimus Multicenter Heart Study Group.

BACKGROUND: Tacrolimus (FK506) may represent a major advance in the management of allograft rejection after solid organ transplantation. In August 1994 a European heart transplantation pilot study was initiated to assess the efficacy and safety of tacrolimus when administered exclusively through an oral route. METHODS: Eighty-two heart transplant recipients were randomized to treatment (2:1 ratio) with either tacrolimus- (n=54) or cyclosporine-based therapy (n=28). RESULTS: No significant differences were evident between the two treatment groups in either rejection or survival rates at 1 year. Kaplan-Meier estimates of the freedom from rejection were 26.3% and 18.5%, respectively, for the tacrolimus and cyclosporine treatment groups (p=.444). Survival rates were 79.6% and 92.9% (p=.125). At 3 of the 5 centers, patients received antithymocyte globulin during the immediate postoperative period and fared better than those who did not (with acute rejection-free rates of 49.2% and 26.7% for tacrolimus and cyclosporine, respectively [p=.080], as opposed to 7.1% and 8.3% [p=.965]; patient survival rates of 84.6% and 93.3% [p=.382] vs 75.0% and 92.3% [p=.243]). The overall rates of infection, impaired renal function (31.5% vs 21.4%), and glucose intolerance (7.0% vs 4.3%) did not differ significantly between the tacrolimus and cyclosporine treatment groups. Tacrolimus seemed to possess an advantage with regard to a reduced requirement for antihypertensive therapy (59.5% vs 87.5%, p=.025). CONCLUSIONS: Immunosuppression with oral tacrolimus provides a viable alternative to treatment with cyclosporine, particularly when administered in conjunction with antibody therapy. Further studies are warranted to optimize the administration of tacrolimus in this indication.

Administration, Oral↗