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Biomedical subjects

G Heinz

Publications and source records attributed to G Heinz.

At least 91 records · Page 5Linked to original sources
PubMed1992

Renal replacement therapy in type 2 diabetic patients: 10 years' experience.

The objective of this study was to determine the impact of renal transplantation and hemodialysis treatment on outcome of elderly diabetic patients with end-stage renal disease (ESRD) among other factors related to survival. Results of treatment of ESRD in 78 patients with non-insulin-dependent diabetes mellitus (type 2) showed a survival rate of 58% at 1 year and 14% at 5 years, independent of treatment modality. Patients who received a renal allograft had a higher survival rate as compared with patients on hemodialysis treatment (5-year survival, 59% v 2%; P < 0.005). Diabetic patients with a history of myocardial infarction, stroke, or peripheral gangrene before onset of renal replacement therapy had a worse prognosis in comparison to patients without vascular complications (5-year survival, 2% v 21%; P < 0.05). Analysis of patients who survived less than 6 months and more than 24 months was performed. Long-term survivors were slightly younger, had diabetes for a shorter period, and showed a better metabolic control of diabetes mellitus. Sixteen long-term survivors received a renal allograft. In contrast, only three short-term survivors were transplanted. Furthermore, short-term survivors also had a greater than 70% incidence of severe vascular complications before renal replacement therapy. A history of myocardial infarction, stroke, or peripheral gangrene is an independent predictor of decreased survival, irrespective of whether the patients were transplanted or maintained on chronic hemodialysis treatment. In contrast, renal transplantation improved survival of elderly diabetic patients without vascular complications and should be the treatment of choice in this specific group of patients.

Aged↗
PubMed1992

Drug-testing in patients with pulmonary hypertension of unknown cause.

The acute haemodynamic effects of seven different drugs were serially evaluated in eight patients suffering from pulmonary hypertension of unknown cause. The following drugs were tested in randomized order: nifedipine, amrinone, isoproterenol, captopril, prostacyclin, dihydralazine and nitroglycerin. Only a reduction in pulmonary vascular resistance (PVR) of more than 30% of baseline was considered a satisfactory response. Overall, the decrease in PVR ranged from 9 +/- 12% (nitroglycerin) to 38 +/- 23% (prostacyclin). However, marked inter- and intra-individual variability in the efficacy of all drugs was observed, making cross reactivity totally unpredictable. The number of responders for each drug varied between five (prostacyclin) and zero (dihydralazine, nitroglycerin). Conversely, a maximum of three drugs was capable of eliciting a response in an individual patient, with only two out of eight patients being total non-responders. A reduction in PVR of more than 30% (n = 16) was associated with a significant decrease in mean pulmonary artery pressure (49.1 +/- 8.2 versus 39.4 +/- 6.4 mmHg) and a significant increase in cardiac index (2.5 +/- 0.6 versus 3.4 +/- 0.8l.min-1.m-2). Overall, none of the drugs tested proved to be clearly superior. However, because of marked inter- and intra-individual variability, the therapeutic approach must be based on trial and error and the evaluation of all drugs is indicated if one fails.

Adult↗
PubMed1992

Long-term intrinsic pacemaker function in patients paced for sinus node deficiency after cardiac transplantation.

Fifteen cardiac transplant recipients requiring permanent pacing (AAI, n = 9; VVI, n = 6; rate responsive devices, n = 11) for postoperative sinus node (SN) insufficiency underwent evaluation of long-term SN function 240 to 1,461 days after transplantation. The intrinsic rhythm at the time of discharge was sinus in 7 patients; junctional escape in 6 patients; and pacemaker dependent in 2 patients. At follow-up, 5 patients had regained regular sinus rhythm, accounting for a total of 11 patients in sinus rhythm while 4 patients were in junctional bradycardia. The SN recovery time as determined by the permanent pacemaker was normal (< 1,500 msec) in only 1/8 patients in whom it was determined, although 4 of these 8 patients were temporarily overriding the pacemaker during ambulatory monitoring. Patients with pathological SN recovery times included 3 patients with late return of sinus rhythm and 4 patients who had recovered normal sinus rhythm before their discharge from the hospital. Three patients developed late symptoms despite apparent early normalization and underwent delayed pacemaker implantations on postoperative days 35, 52, and 225, respectively. We conclude that, in patients requiring pacemaker implantation after cardiac transplantation, normalization of SN function cannot be inferred from just return of sinus rhythm, regardless of whether it occurs early or late. These findings may have implications when a pacemaker exchange or explantation is being considered.

Electrocardiography↗
PubMed1992

Prognostic value of heart rate variability in patients awaiting cardiac transplantation.

Time and frequency domain parameters of heart rate variability (HRV) were determined in patients with severe endstage heart failure awaiting cardiac transplantation (HTX). These parameters were then correlated with mortality to investigate the performance of HRV in discriminating between groups with high and low risk of death. The standard deviation of five consecutive RR intervals (SDANN) was found to be the parameter with the greatest sensitivity (90%) and specificity (91%). Patients with SDANN values of < 55 msec had a twenty-fold increased risk of death (90% confidence limits: 4-118, P < 0.001). The results furthermore suggest that measurements of HRV are superior to other prognostic markers such as left ventricular ejection fraction, pulmonary artery wedge pressure, cardiac index, and serum sodium levels. We conclude that HRV is a powerful, noninvasive tool to assess the risk of death in candidates for HTX. HRV measurements can therefore be used as a supplement to other markers of risk to determine the optimal therapeutic strategy in patients with severe congestive heart failure.

Adult↗
PubMed1992

Sinus node dysfunction after orthotopic cardiac transplantation: postoperative incidence and long-term implications.

We investigated incidence, normalization rates, and clinical significance of sinus node (SN) dysfunction after cardiac transplantation. Thirty-nine of 90 patients systematically evaluated presented with impaired SN function in the postoperative period. Of these, 22 normalized their SN function during follow-up while 17 remained impaired after 3 months. The proportion normalized was higher in patients with prolonged SN recovery time (11/16, 68.8%) and those reverting from escape rhythm to sinus rhythm until discharge (5/8, 62.5%) when compared to patients in escape rhythm throughout the postoperative period (5/11, 45.5%) or pacemaker dependence (1/4, 25%). There was no reliable postoperative predictor of normalization and necessity of long-term pacing. A postoperative heart rate consistently less than 70 beats/min (irrespective of the native rhythm) was significantly related to outcome (P = 0.01), but revealed unacceptable sensitivity (61.5%) and specificity (81%). After all, both patients with severe symptoms (near syncopes and syncope), were derived from this group. These two patients, who had been discharged in sinus rhythm, had late pacemakers implanted. An additional 17 patients had early pacemaker placement, only seven of which were constantly paced during follow-up. Given the low normalization rates, patients with postoperative escape rhythm are those most likely to benefit from pacemaker therapy over the long term. Even those in, or reverting back to, sinus rhythm until discharge may experience severe symptoms, particularly in the setting of a postoperative rate consistently less than 70 beats/min since this indicates a relatively lower probability of recovery.

Algorithms↗
PubMed1992

Postoperative sinus node dysfunction in the transplanted heart. Impaired automaticity but normal refractoriness.

We describe the use of the extrastimulus technique to define the range of sinus node (SN) effective refractoriness (SNERP) in the denervated transplanted human heart. SNERP could be successfully determined in 18 of 28 patients corresponding to 25 of 43 SN studies and ranged from 210 to 360 ms at a basic pacing cycle length of 500 ms (95 percent confidence limits: 252.5 to 296.2 ms), which is shorter than reported in the innervated native heart. Sixteen data sets in 12 patients showed normal SN function and nine sets of measurements in seven patients showed abnormal SN function (corrected SN recovery time greater than 520 ms). While recovery time was profoundly abnormal (279.7 +/- 94 vs 7,284.8 +/- 10,454, p less than 0.001), the SNERP did not differ significantly between the groups (274.3 +/- 40 vs 286 +/- 42 ms at 500 ms, p = 0.5) and was normal at a range of 220 to 340 ms even in those patients with grossly impaired SN recovery (SNERP in patients with normal SN function: 210 to 360 ms at 500 ms). This study demonstrates that SN refractoriness in the transplanted human heart is shorter than previously reported in innervated controls and suggests that posttransplantation SN dysfunction is characterized by impaired automaticity rather than impaired refractoriness.

Adult↗
PubMed1992

[Ablation of AV nodal tachycardia: new aspects on mechanism and therapy].

Dual AV nodal pathways are the substrate for the occurrence and induction of AV nodal reentry tachycardias (AVNRT). Characteristics of fast or slow pathway conduction are amenable to selective ablation by radiofrequency energy. Thus, the substrate of AVNRT is eliminated with preservation of antegrade AV nodal conduction. Radiofrequency catheter ablation is a highly effective and safe modality of treatment with success rates ranging from 80 to 100%. The risk of inadvertently inducing complete heart block is substantially lower with slow when compared to fast pathway ablation. Thus, selective ablation of slow pathway conduction has been recently advocated as the procedure of choice. When regarding to concomitant atrial fibrillation or flutter, ablation of slow pathway conduction might be preferable given the resulting higher antegrade Wenckebach cycle lengths after slow pathway ablation.

Atrioventricular Node↗
PubMed1992

The determinants of elevated total plasma cholesterol levels in cardiac transplant recipients administered low dose cyclosporine for immunosuppression.

Elevated total plasma cholesterol level is a frequent finding after cardiac transplantation. To identify risk factors for the development of hypercholesterolemic states, we applied multivariate statistics in a logistic and linear manner. Six-month posttransplantation levels of total plasma cholesterol in 57 adult heart recipients were available for analysis. Maintenance immunosuppression was carried out with either cyclosporine and azathioprine or both agents plus low-dose steroids. Total plasma cholesterol levels were dichotomized for the logistic analysis (1) by the age- and sex-matched 75th and 90th percentiles of a reference population according to National Institutes of Health treatment guidelines and (2) by the cut point 250 mg/dl. Twelve potential risk factors were evaluated as covariates: recipient age, body weight after 6 months, body weight gain over 6 months, body mass index after 6 months, body mass index gain over 6 months, current cyclosporine dosage, trough level of cyclosporine in whole blood according to high-performance liquid chromatography after 6 months, cumulative cyclosporine dosage over 6 months, serum bilirubin, type of original cardiac disease, maintenance steroids, and steroid bolus treatment. Multivariate logistic regression yielded the type of original cardiac disease as a significant predictor of posttransplantation hypercholesterolemia exceeding the 90th percentile (p = 0.019) and of hypercholesterolemia exceeding 250 mg/dl (p = 0.032). Maintenance steroids were identified as a second significant cofactor (p = 0.069) for total plasma cholesterol levels exceeding 250 mg/dl. Multiple linear regression again revealed the type of original cardiac disease and maintenance steroids as significant predictors by p values of 0.005 and 0.013, respectively. Patients with coronary artery disease as the original cardiac pathology and low-dose maintenance steroids had the greatest risk for the development of elevated total plasma cholesterol levels after cardiac transplantation. However, the overall predictive quality of the linear model was limited (multiple r value 0.43), which indicates that other variables besides the tested ones attributed to elevated total plasma cholesterol levels. These results confirm the adverse role of maintenance steroids on posttransplantation hypercholesterolemia and demonstrate the type of original cardiac disease as the most important risk factor. They suggest that abnormalities of lipoprotein metabolism and dietary factors continue to affect total plasma cholesterol levels after cardiac transplantation.

Adult↗
PubMed1992

T-cell selection and T-cell receptor variable beta-chain usage in chronic hemodialysis patients.

Thymic and extrathymic selection processes are responsible for the shape of the T-cell repertoire. T-cell receptor (TCR) variable (V) chain usage, holding a place in tolerance, autoimmunity and response to external agents, was analyzed in 41 patients maintained on chronic hemodialysis treatment. Leukocyte (mean: 6444 +/- 2277 cells/microliters), lymphocyte (mean: 1457 +/- 707 cells/microliters) and T-cell (mean: 67 +/- 16%) counts were within expected limits, but hemodialysis patients showed an impressive increase of TCR V beta 6.7 positive peripheral blood lymphocytes (PBL) and a massive deletion of TCR V beta 8 positive PBL. V beta 6.7 positive PBL were detectable in all hemodialysis patients (n = 41, mean: 2.47 +/- 1.61% PBL) in contrast to a healthy population, where only 45% of subjects expressed V beta 6.7 on PBL (n = 9, mean: 3.50 +/- 1.83% PBL). Only 27% of our hemodialysis patients expressed V beta 8 on PBL (n = 11, mean: 1.00 +/- 1.94% PBL) in contrast to healthy subjects, who presented V beta 8 positive PBL (n = 20, mean: 2.89 +/- 1.23% PBL) in every case. Neither primary kidney disease, nor response to vaccination for hepatitis-B, nor dialyzer membranes used, were associated with these alterations of the TCR V beta-pool. It is likely, that the well-known impairment of the cytokine network in chronic renal failure, uremic toxins or response to infectious agents, may contribute to these different and possibly independent T-cell selection mechanisms in uremia.

Cell Separation↗
PubMed1991

Decreased postheparin lipolytic activity in renal transplant recipients with cyclosporin A.

The patterns of hyperlipidemia in renal transplant recipients (RTRs) are more variable than in the uremic state, showing increases in both very low-density lipoprotein (VLDL) and low density lipoprotein (LDL). This has been attributed, at least in part, to immunosuppressive therapy, especially to treatment with corticosteroids. Postheparin lipolytic activity (PHLA) was determined in 28 RTRs. Sixteen patients presenting with hyperlipidemia comprised group A, who were aged 49.8 +/- 13.5 years, and had a cholesterol of 8.24 +/- 1.86 mmol/liter, triglycerides of 6.02 +/- 3.33 mmol/liter. Twelve patients presenting cholesterol and triglyceride values within the normal range were in group B, and were aged 48.6 +/- 13.3 years. All RTRs received cyclosporin A (CsA) twice daily orally, which were divided in two equal doses and adjusted to provide CsA blood trough levels (RIA) in a range of 250 to 350 ng/ml. Twenty-one RTRs were additionally treated by alternate-day corticosteroids, whereas seven patients had CsA on their sole immunosuppressive agent. PHLA (mumol free fatty acids/ml/hr, given 10 and 20 min after 100 U/heparin kg body wt intravenously) was commonly reduced in RTRs (group A at 10/20 min: 5.6 +/- 1.1/5.26 +/- 1.2; group B: 8.26 +/- 2.91/8.38 +/- 3.44) as compared to the values obtained in healthy controls (15.3 +/- 2.9/17.2 +/- 5.0). This was mainly due to a reduction of the activity of the hepatic triglyceride lipase, and to a minor extent to a reduced activity of peripheral lipoprotein lipase. There was no statistically significant difference of PHLA in RTRs with or without corticosteroid treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Cortex Hormones↗
PubMed1991

Contribution of splanchnic and peripheral vascular tissues to the disposal of angiotensin-II and to regional conversion rates of angiotensin-I: a pilot study in humans.

The present study investigates angiotensin-II (A-II) balance across the splanchnic vascular bed and leg vascular tissues in humans, at baseline conditions and following a systemically ineffective femoral arterial angiotensin-I (A-I) infusion, both before and during inhibition of angiotensin-converting enzyme (ACE) with enalaprilat. In six healthy men, net regional A-II balance was calculated from the transfemoral or transsplanchnic arteriovenous differences in plasma concentrations and the corresponding regional plasma flow. Systemic and splanchnic hemodynamics remained unchanged throughout the trial, indicating an absence of major hemodynamic effects during A-I infusion or concomitant ACE inhibition. In contrast, regional leg plasma flow significantly decreased following A-I infusion (165.2 +/- 15.7 vs. 304.7 +/- 43.7; p less than 0.01) and again gradually returned to about baseline values after ACE inhibition. Baseline net transfemoral A-II balance was equilibrated at slight formation rates in four subjects and at minimal extraction rates in two of the six subjects. Following A-I infusion, a shift toward net femoral A-II formation (average increase 2,774% above baseline) was observed in all subjects (p less than 0.01). After concomitant ACE inhibition, femoral A-II balance again returned to baseline levels. Across the splanchnic vascular bed a net baseline. A-II extraction was observed in all subjects. Following A-I infusion an average increase by 285% (p less than 0.05) in splanchnic A-II extraction was observed. During concomitant ACE inhibition splanchnic A-II extraction tended to decrease toward baseline values in four subjects, and remained rather unchanged in two subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Demographic and perioperative factors associated with initial and prolonged sinus node dysfunction after orthotopic heart transplantation. The impact of ischemic time.

The etiology of sinus node (SN) dysfunction after orthotopic heart transplantation as assessed by the origin of rhythm, heart rate (HR), and, provided the origin of rhythm was sinus, by corrected sinus node recovery time (CSNRT) was studied in 50 patients. The possible influences on postoperative donor SN function of donor age, recipient age, underlying pretransplant heart disease, pretransplant amiodarone (AMIO) treatment, date of surgery, ischemic time, surgical technique of atrial incision, the use of different cardioplegic solutions during the study period, and rejection were evaluated. The results thus obtained indicate that SN dysfunction is common after cardiac transplantation and pinpoint to a different etiology of transient (restoration of normal SN function within 4 postoperative weeks) and persistent (SN function still impaired at 3 months) SN dysfunction. Of the several demographic and perioperative variables evaluated, only ischemic time had an influence on postoperative SN function in that ischemic times were significantly longer in patients with impaired SN function when compared with patients exhibiting normal SN function (148 +/- 39 min vs. 110.5 +/- 36 min, respectively, P = 0.001). Further stratification according to the duration of SN dysfunction revealed significantly longer ischemic times in patients with transiently impaired SN function only (156.3 +/- 35 min vs. 110.5 +/- 36 min, P = 0.0026). No relation to persistent SN dysfunction of ischemic time (130.5 +/- 36 min vs. 110.5 +/- 36 min, P = ns) or any other factor investigated was found.

Amiodarone↗
PubMed1991

[Visually evoked P300 waves].

The event-related potentials after a competitive visual stimulation are presented. The stimulation with target stimuli results in two pronounced positive potentials in the grand-average, the P2 and the P3 component of the ERP, and a long-lasting positivity following the P3 wave. Similar but smaller potential components are elicited by non-target stimuli. Some examples of individual ERP demonstrate the high degree of inter-individual variability, as in the positive components as in the restoration of the poststimulus baseline. Some aspects of a possibly fundamental difference between visually and acoustically elicited P300 waves are demonstrated.

Acoustic Stimulation↗
PubMed1991

Contribution of leg vascular tissues to the overall metabolic clearance of human atrial natriuretic factor (hANF) in man.

From experimental studies it has been suggested that considerable peripheral clearance of human atrial natriuretic factor (hANF) might occur. In healthy men (n = 7) the peripheral fractional extraction of hANF was about 35% under basal conditions resulting in hANF-uptake across the leg vascular bed of 2.1 +/- 2.4 pMol/min and regional leg clearance rate of 102.6 +/- 88.2 ml/min, which is approximately 2.5% of the total metabolic clearance rate. During a primed constant i.v. infusion of hANF (bolus 100 micrograms; infusion 100 micrograms/h, t = 1h) arterial and venous plasma concentrations of hANF increased about 10-fold (p less than 0.05), however, estimated leg blood flow as well as leg fractional extraction, leg uptake and clearance rates of hANF did not significantly change as compared to baseline. Total metabolic clearance rates and apparent production rates of hANF were 4.05 +/- 1.93 l/min and 84.1 +/- 29.9 pMol/min, respectively. We conclude that in healthy man the leg vascular bed does not play a major regulatory role in the metabolism of exogenously infused hANF. However, our results suggest that the peripheral vasculature is, to a certain extent, involved in the metabolic clearance of endogenous hANF and thus, contributes to the peptide's overall disposal.

Adult↗
PubMed1991

Predictive value of thallium-201-dipyridamole myocardial stress scintigraphy in chronic hemodialysis patients and transplant recipients.

The prognostic impact of thallium(Tl)-201-dipyridamole (DPM) stress and redistribution scintigraphy done in 36 patients on chronic hemodialysis (HD) and in 23 renal transplant recipients (TRs) was evaluated according to cardiovascular complications and survival in a follow-up period of six years. Though symptomatic ischemic heart disease (IHD) was present in 33% of HD patients and in 17% of TRs, 50% and 39%, respectively, had Tl-201 findings indicative of IHD. The duration of HD treatment was similar for patients with an abnormal or normal scintigraphic finding. Abnormal Tl-201 results were seen more frequently in older patients. During follow-up, 27 of 36 HD-patients died, 16 had an abnormal and 11 a normal Tl-201-DPM finding; cardiovascular complications were the cause of death in 88% and 18% of these patients, respectively. Thus the incidence of death from fatal cardiac events was 12% per year at risk for the former and 1.9% per year at risk for the latter. In TRs survival was not different for patients with an abnormal or normal Tl-201 finding (56% vs. 64%). However, fatal or nonfatal cardiovascular events were seen more frequently in patients with an abnormal Tl-201 results (78% versus 7%; p less than 0.0001). Stepwise logistic analysis and survival analysis demonstrated Tl-201-DPM stress/redistribution scintigraphy to be the only predictor for identifying patients at increased risk for cardiovascular events. In patients with abnormal Tl-201-DPM scintigraphy subsequent survival was extended for symptomatic patients as compared to asymptomatic ones )30.3 +/- 21.6 versus 22.0 +/- 17.3 months; p less than 0.008).

Adult↗