Biomedical subjects

H Kreuzer

Publications and source records attributed to H Kreuzer.

At least 37 records · Page 2Linked to original sources

PubMed1997

Evaluation of an active coronary perfusion balloon device using Doppler flow wire during PTCA.

The aim of this study was to assess whether active coronary perfusion catheters (APC) can provide a sufficient coronary flow in large caliber vessels during balloon inflation. To prevent myocardial ischemia during PTCA, these APC may be employed. However, it is as yet unknown whether the active flow rate of these devices approaches the flow rate prior to PTCA during balloon inflation. Therefore, we measured the efficacy of the APC during balloon inflation in vessels supplying a large amount of myocardium. In 12 patients (1 female, 11 males, 53 +/- 12.6 yr) with stenosed vessels (average diameter 3.4 +/- 0.26 mm), the coronary flow velocity was measured using a 0.014" Doppler guidewire, which was placed distally bypassing the balloon of the APC. The active perfusion balloon catheter was advanced through a 7F guiding catheter along a 0.014" guidewire. After removal of the guidewire, arterial blood being withdrawn from the side port of the femoral angioplasty sheath was pumped through the catheter to the distal coronary vessel. The perfusion volumes of the pump were set to different levels between 30 to 60 ml/min. Intracoronary flow rate was calculated by the angiographically assessed vessel luminal area [symbol: see text] average peak velocity [symbol: see text] 0.5. The mean coronary flow rate prior to PTCA was 43 +/- 17.7 ml/min. Maximum flow during PTCA was 55 +/- 19.6 ml/min. We found a good correlation between the preset external pump rate and the coronary flow in situ (r = 0.92). Pre-PTCA flow rates were achieved in 11 of 12 patients (92%) during balloon inflation. No relevant decrease in the arterial pressure occurred during dilation times of 4.6 +/- 1.63 min. Only two patients showed significant ECG changes during these balloon inflations. After an average follow-up period of 13 +/- 6.3 mo, only one patient (8%) had a significant re-stenosis requiring the implantation of a stent. The combination of intravascular Doppler velocity measurements with quantitative coronary angiography offers the opportunity of exact online flow registration during angioplasty. Using APC, It is possible to maintain a sufficient coronary flow in the distal vessel during balloon inflation even in large vessels. Therefore, as compared with mechanical circulatory assist devices, coronary assist by APC is a little invasive, but according to our measurements it might be a sufficient tool for performing PTCA also in high-risk patients.

Adult↗

PubMed1997

[Embolic complications in bacterial endocarditis].

Embolic complications are a major prognostic determinant in the clinical course of infective endocarditis (IE) with an incidence of about 30-50%. In order to analyze risk factors leading to embolism in native (NVE) and prosthetic valve endocarditis (PVE), we reviewed 177 consecutive patients; 43% were female, 57% male, PVE occurred in 24% of all patients all left-sided, among the NVE were 11% right-sided IE. Major embolic complications occurred in 40% of all patients. In NVE, a higher rate of embolic events (45% vs. 26%; p < 0.05), and a larger vegetation size compared to PVE was observed (14 +/- 6 mm vs. 11 +/- 5 mm; p < 0.05). The most important risk factor for embolic complications in NVE was Staphylococcus aureus (odds ratio 6.4). Furthermore, double valve endocarditis, fever, and mitral valve endocarditis were associated with the risk for embolism. In case of severe regurgitation the rate of embolic complications was reduced (54% vs. 77%; p < 0.05). In PVE, fever was a risk factor for embolic events. Staphylococcus aureus was also a frequent microorganism in embolism (45% vs. 22%). The in-hospital mortality was significantly increased in case of embolism (NVE 40% vs. 11%; p < 0.001; PVE 36% vs. 9% p < 0.05). About 50% of all embolic events occurred before admission. In NVE, due to high in-hospital mortality, the rate of patients with embolism undergoing surgery was lower (57% vs. 72%; p < 0.05); whereas in PVE no significant difference was observed. In patients with NVE, aspirin therapy because of coronary artery disease appeared to reduce the rate of embolic complications (11% vs. 47%). However, the low number of patients on aspirin (9%) does not allow recommendations regarding a potential benefit. In conclusion, identification of risk factors leading to embolism in IE may be useful in considering early surgical therapy. However, the high rate of embolic complications before hospital admission indicates a need for improving the diagnostic delay in the prehospital phase.

Adult↗

PubMed1997

Causes of failed angioplasty for acute myocardial infarction assessed by intravascular ultrasound.

Coronary angioplasty is gaining increased importance as a primary treatment of acute myocardial infarction, but the complication rate of the procedure is higher than in stable coronary artery disease. In a consecutive series of 110 coronary angioplasties in patients with acute myocardial infarction, the cause of initially failed procedures was studied by intravascular ultrasound. The balloon angioplasty was immediately successful in 66%. In those cases with crossing of the lesion but a dissatisfying dilatation result (persistent occlusion, reocclusion, or dissection) an intravascular ultrasound probe could be advanced to 32 of 34 lesions. The information provided by ultrasound guided the subsequent bailout therapy. Persistent occlusions were caused by extensive thrombosis in 4.5% of all cases, subsequently treated by local thrombolysis for 12 to 16 hours, and in 1.8% by a ruptured plaque, which was treated by stenting. In cases with Thrombolysis in Myocardial Infarction (TIMI) flow II, angiography suggested a thrombus in 9.1%, but intravascular ultrasound could detect dissections instead of a thrombus in half the cases. In cases of dissection, stenting was performed. Dissections were observed by angiography in 15.5%, and all cases were confirmed by ultrasound. In vessels >2.5 mm the dissection was treated by stenting. Overall, in 20 of 21 lesions stents were successfully implanted. No stent thrombosis was observed. With the assistance of intravascular ultrasound during bailout therapy, the success of coronary angioplasty to achieve TIMI flow III without residual stenosis in an unselected consecutive patient cohort with acute myocardial infarction was 96%. In direct angioplasty for acute myocardial infarction the procedure is frequently complicated by events such as plaque rupture and extensive vascular thrombosis, which are uncommon in coronary angioplasty for stable angina. Intravascular ultrasound provided insight into the underlying morphologic characteristics of failed angioplasty that enhanced the information provided by coronary angiography and assisted in the selection of the bailout therapy.

Aged↗

PubMed1997

Mipafox differential inhibition assay for heart muscle cholinesterases: substrate specificity and inhibition of three isoenzymes by physostigmine and quinidine.

1. A differential inhibition assay was developed for the quantitative determination of cholinesterase isoenzymes acetylcholinesterase (AChE; EC 3.1.1.7), cholinesterase (BChE; EC 3.1.1.8), and atypical cholinesterase in small samples of left ventricular porcine heart muscle. 2. The assay is based on kinetic analysis of irreversible cholinesterase inhibition by the organophosphorus compound N,N'-di-isopropylphosphorodiamidic fluoride (mipafox). With acetylthiocholine (ASCh) as substrate (1.25 mM), hydrolytic activities (A) of cholinesterase isoenzymes were determined after preincubation (60 min, 25 degrees C) of heart muscle samples with either saline (total activity, A tau), 7 microM mipafox (AM1), or 0.8 mM mipafox (AM2): (BChE) = A tau-AM1, (AChE) = AM1-AM2, (Atypical ChE) = AM2. 3. The mipafox differential inhibition assay was used to determine the substrate hydrolysis patterns of myocardial cholinesterases with ASCh, acetyl-beta-methylthiocholine (A beta MSCh), propionylthiocholine (PSCh), and butyrylthiocholine (BSCh). The substrate specificities of myocardial AChE and BChE resemble those of erythrocyte AChE and serum BChE, respectively. Michaelis constants KM with ASCh were determined to be 0.15 mM for AChE and 1.4 mM for BChE. 4. Atypical cholinesterase, in respect to both substrate specificity and inhibition kinetics, differs from cholinesterase activities of vertebrate tissue and, up to now, could be identified exclusively in heart muscle. The enzyme's Michaelis constant with ASCh was determined to be 4.0 mM. 5. The reversible inhibitory effects of physostigmine (eserine) and quinidine on heart muscle cholinesterases were investigated using the differential inhibition assay. With all three isoenzymes, the inhibition kinetics of both substances were strictly competitive. The physostigmine inhibition of AChE was most pronounced (Ki = 0.22 microM). Quinidine most potently inhibited myocardial BChE (Ki = 35 microM).

Animals↗

PubMed1997

Vasodilation by urapidil in the treatment of chronic congestive heart failure in addition to angiotensin-converting enzyme inhibitors is not beneficial: results of a placebo-controlled, double-blind study.

BACKGROUND: The therapeutic benefit of an angiotensin-converting enzyme (ACE) inhibitor in combination with a different type of vasodilator is unknown. METHODS AND RESULTS: To evaluate the effects of a combined therapy on quality of life, exercise tolerance, and hemodynamic parameters, patients with severe heart failure (New York Heart Association classes III and IV, ejection fraction below 35%) who were on ACE inhibitor therapy were randomly assigned to additional double-blind treatment with urapidil (60-120 mg/d) or placebo for 12 weeks. After enrollment of 36 patients, the study was terminated early because no beneficial effects on exercise tolerance and hemodynamic parameters could be shown for the urapidil treatment, and a trend toward increased mortality of the urapidil group was observed (odds ratio, 4.92 [0.49-49.6]; P = .167). CONCLUSION: The combination of urapidil with an ACE inhibitor in the treatment of severe chronic congestive heart failure does not seem to offer any advantages over therapy with an ACE inhibitor alone and may have potentially harmful effects.

Adult↗

PubMed1997

Additional luminal area gain by intravascular ultrasound guidance after coronary stent implantation with high inflation pressure.

AIMS: Studies by intravascular ultrasound demonstrated inadequate expansion in a large number of stents, which lead to the increase of inflation pressure for stenting. The present study examined whether routine use of high-pressure inflation would be sufficient for an optimum stent expansion without sonographic guidance. METHODS AND RESULTS: Two types of single coronary stents (Palmaz-Schatz in 54, and Wiktor in 25) were implanted with inflation pressures of 16-20 atm in 79 nonocclusive coronary lesions. IVUS before stenting was used in 78% to select the adequate stent size. Intravascular ultrasound after stenting was used to asses the minimum stent are and diameter, the reference areas, and the strut apposition to the vessel wall. The difference between the area of the expanding balloon and the stent area was calculated as the luminal deficit of the stent. Completeness of stent expansion required full strut apposition and lesion coverage, and a minimum stent area that was larger than the distal reference, and larger than 60% of the proximal reference. Intravascular ultrasound before stenting lead to an increase of the stent size in 47%. After high-pressure expansion, even with the optimized balloon size, 8% of stents had struts protruding into the lumen. The stent area (6.87 +/- 1.93 mm2) was significantly smaller than both the proximal (9.59 +/- 2.91 mm2; p < 0.001) and distal reference area (8.23 +/- 3.03 mm2; p < 0.001). The criteria for complete expansion were met in 48%. The expansion with a larger high-pressure balloon in 28 stents lead to an increase of the stent area by 19% (8.19 +/- 2.24; p < 0.001), and full stent apposition in all cases. The criteria of stent expansion were met in 82%. A wide range of the luminal deficit upto 48% was observed, which was not related to sonographic lesion characteristics, except in lesions with complete circumferential calcifications. The different stent designs were characterized by a slightly lower luminal deficit in slotted-tube stents (23 +/- 13% vs. 28 +/- 12%; p = 0.11) and a better index of stent symmetry as compared with the coil stent (0.87 +/- 0.08 vs. 0.82 +/- 0.09; p < 0.05). CONCLUSION: Routine use of high-pressure stent expansion did not lead to a sufficient stent expansion, even when the initial stent size had been guided by intravascular ultrasound. Further stent dilatation with larger balloons under ultrasound guidance would be required to optimize the luminal area gain.

Adult↗

PubMed1997

Morphology of chronic coronary occlusions and response to interventional therapy--a study by intracoronary ultrasound.

OBJECTIVES: Balloon angioplasty of chronic coronary occlusions has a low procedural success and a high recurrence rate. Better tomographic insights into the lesion morphology may improve the interventional strategy and results. METHODS: Intracoronary ultrasound was used during the recanalizaton procedure of 45 chronic coronary occlusions (2 weeks to 14 months; average 3.4 months) to determine the lesion morphology and to assess the angioplasty result. The luminal area and the plaque burden were measured proximal and distal to the occlusion, and within the occlusion. The ultrasonographic characteristics of the occlusive lesions were compared to 45 nonocclusive lesions of age-matched patients with stable angina pectoris. RESULTS: Occlusive lesions were more often echodense as compared to nonocclusive lesions (35% vs. 20%; p = 0.10). In chronic occlusions a multi-layered plaque morphology was observed in 22%, and this morphology was not found in nonocclusive lesions. Angiographic characteristics were not related to the ultrasonographic morphology of the lesion. Despite similar vessel areas in occlusive and nonocclusive lesions, the balloon size selected according to the angiographic image was underestimated in occlusive lesions. Based on the quantitative ultrasound measurement the balloon size was increased from 2.6 +/- 0.3 mm to 3.3 +/- 0.5 mm in 53% of the lesions. This resulted in an increase of the luminal area from 3.51 +/- 0.92 to 5.08 +/- 1.43 mm2 (p < 0.001). The acute recoil after balloon angioplasty was similar (34 +/- 18%) in hypodense and echodense plaques, but was significantly higher in lesions with a multi-layered plaque morphology (49 +/- 22%; p < 0.05). In 19 patients with severe dissections or extreme acute recoil (residual stenosis > 50%) the use of a stent increased the luminal area from 3.94 +/- 0.81 to 7.51 +/- 1.71 mm2 (p < 0.001). CONCLUSIONS: Intracoronary ultrasound demonstrated a multi-layered plaque morphology in one fourth of the chronic occlusions. This type of plaque was associated with a significant acute recoil. The presence of diffuse atherosclerosis in neighbouring segments of chronic coronary occlusions leads to underestimation of the balloon size. Quantitative assessment by intracoronary ultrasound helped to optimize the balloon size leading to a significant luminal area gain. The detection of excessive acute recoil should be considered an indication for stent deployment.

Angioplasty, Balloon, Coronary↗

PubMed1997

Inhibition of the voltage-dependent calcium current by extracellular ATP in hamster ventricular cardiomyocytes.

The modulation of the high-voltage-activated calcium current (ICa) by external ATP was examined in single ventricular cardiomyocytes of the hamster using the whole-cell configuration of the patch-clamp technique. Extracellular application of ATP (0.1-100 microM) was found to inhibit ICa reversibly. The inhibition followed a slow time course (half time approximately 25 s) and was accompanied by very small changes of the holding current and no shift in the current-voltage relationship. With 100 microM ATP, peak ICa was reduced by approximately 30%. This response was not blocked by the P1 inhibitor 8-cyclopentyl-1,3-dipropylxanthine. The nonhydrolyzable ATP analogs adenosine 5'-O-(3-thiotriphosphate) and AMP-adenosine 5'-[beta,gamma-imido]triphosphate also reduced ICa. The ATP analog alpha,beta-methylene-ATP was about equipotent with ATP at 50 microM. Internal guanosine 5'-O-(3-thiotriphosphate) (200 microM) rendered the ATP-mediated inhibition of ICa poorly reversible, whereas internal guanosine 5'-O-(2-thiodiphosphate) (200-500 microM) had no effect. Holding the intracellular adenosine 3',5'-cyclic monophosphate concentration at a constant high level did not alter the ATP response. We conclude that external ATP inhibits ICa via a P2 purinergic receptor in hamster ventricular myocytes. Our results suggest the involvement of a G protein not coupled to adenylate cyclase. The inhibition of ICa by extracellular ATP might have pathophysiological relevance under conditions of myocardial injury.

Adenosine Triphosphate↗

PubMed1997

[Development and evaluation of a spectroscopy system for classification of laser-induced arterial fluorescence spectra].

The present study evaluated the potential of fluorescence guidance of laser angioplasty without using a second laser for fluorescence excitation. A prototype spectroscopy system with a grating spectrograph, microchannel plate, CCD array and digital image processor on a personal computer was developed and coupled to a clinical XeCl excimer laser. Using multifibre catheters, specimens of human aorta were ablated in physiological saline and blood. The spectra thus generated were recorded and validated histologically. Five types of spectra could be differentiated. Based on a training set, classification algorithms were developed using multiple linear regression and linear discriminant analysis with intensity ratios as predictor variables. Discriminant analysis yielded prospective classification of the remaining validation spectra with high sensitivity and specificity for each type. These data demonstrate that fluorescence spectroscopy during excimer laser ablation at 308 nm does not require a diagnostic laser. Principal types of atherosclerotic lesions and the media can be differentiated spectroscopically in physiological saline and blood.

Adult↗

PubMed1996

Cheyne-Stokes respiration and prognosis in congestive heart failure.

Patients with congestive heart failure (CHF) frequently demonstrate Cheyne-Stokes respiration (CSR) with repetitive arousals and oxygen desaturations during sleep. Although it was evident from early publications that CSR during the daytime is a poor prognostic indicator in patients with CHF, it was speculated recently that CSR occurring during sleep could impede left ventricular function and even survival. We therefore followed up 36 patients with CHF and a left ventricular ejection fraction < or = 40% who underwent a sleep study at our institution. The patients showed a reduced ejection fraction (20 +/- 8%) and CSR with a median of 19% of total sleep time (lower and upper quartiles 9% and 56%). In 12 +/- 9% of their time in bed, the arterial oxygen saturation was <90%. No patient was lost to follow-up, which lasted for 32 +/- 15 months (range 11 to 53). One-year survival was 86 +/- 6%, and 2-year survival was 66 +/- 8%. Univariate comparisons for survival between groups stratified by the amount of CSR revealed no significant difference (log rank test, p = 0.84). However, the 20 patients with a left ventricular ejection fraction <20% had a shorter mean survival time than patients with an ejection fraction >20% (9.5 vs 28.3 months; log rank test, p = 0.013). Two patients with CSR during the daytime died within 1 month. No other patient had CSR during the daytime, and only 1 patient without daytime CSR died within 1 month (chi-square test, p <0.001). Higher age, reduced carbon dioxide end-tidal partial pressure, and increased transit time were found to be significantly related to the amount of nocturnal CSR. In conclusion, CSR occurring during sleep has no important prognostic impact in patients with CHF, but CSR present during the daytime suggests a high likelihood of dying within a few months.

Aged↗

PubMed1996

Radiofrequency catheter ablation of right ventricular tachycardia late after repair of congenital heart defects.

BACKGROUND: Ventricular arrhythmias after repair of congenital heart defects are a common finding and possibly contribute to sudden death in these patients. Optimal antiarrhythmic management has not yet been defined. METHODS AND RESULTS: The study population consisted of 16 patients in whom ventricular arrhythmias occurred 11 to 42 years after complete surgical repair of congenital heart defects. Fifteen patients had a history of symptomatic sustained or nonsustained ventricular tachycardia, and 1 had frequent nonsustained ventricular tachycardia. The diagnostic mapping procedure to identify the origin of the arrhythmia included pace mapping during sinus rhythm, activation mapping, and pacing interventions during ventricular tachycardia. Catheter ablation was carried out by means of radiofrequency energy in the temperature-controlled mode. The follow-up period was 6 to 33 months (mean, 16 months). A right ventricular origin of the tachycardia in the surgically corrected area could be determined in all patients. Catheter ablation was carried out without complications. Immediate noninducibility was achieved in 15 of the 16 patients. One patient in whom the tachycardia was again inducible at repeat stimulation 1 week later was successfully treated with amiodarone. Eleven patients were taken off antiarrhythmic drugs. During follow-up, none of them had a recurrence of the tachycardia that had been ablated. CONCLUSIONS: In patients with symptomatic or frequent ventricular tachycardia late after complete surgical repair of congenital heart defects, catheter ablation by means of radiofrequency energy is feasible and safe and thus might be taken into consideration for these patients. Short-term follow-up results are promising.

Adolescent↗

PubMed1996

DNA sequence recognition by hybridization to short oligomers: experimental verification of the method on the E. coli genome.

A newly developed method for sequence recognition by hybridization to short oligomers is verified for the first time in genome-scale experiments. The experiments involved hybridization of 15,328 randomly selected 2-kb genomic clones of Escherichia coli with 997 short oligomer probes to detect complementary oligomers within the clones. Lists of oligomers detected within individual clones were compiled into a database. The database was then searched using known E. coli sequences as queries. The goal was to recognize the clones that are identical or similar to the query sequences. A total of 76 putative recognitions were tested in two separate but complementary recognition experiments. The results indicate high specificity of recognition. Current and prospective applications of this novel method are discussed.

Base Sequence↗

PubMed1996

Enhanced detection criteria in implantable cardioverter-defibrillators to avoid inappropriate therapy.

The aim of this prospective study was to evaluate the efficacy and safety of enhanced detection criteria, stability and sudden onset, for ventricular tachycardia (VT) in the therapy of implantable cardioverter-defibrillators (ICDs). These detection enhancements ensure a high specificity in detecting VT, thereby avoiding inappropriate therapy delivery due to supraventricular tachycardia. However, delayed sensing or even undersensing of VT may lead to a problematic, even fatal, outcome. In our study, the stability detection enhancement was programmed to discriminate atrial fibrillation (AF) in 84 of 124 patients with implanted ICDs and the sudden-onset detection enhancement in 47 of the 124 patients to discriminate sinus tachycardia. Using these enhancements in 124 patients with third-generation ICDs, 13 patients (11%) had inappropriate therapy during 20 months of follow-up. AF caused shock delivery in 6 patients (5%) and antitachycardia pacing in 4 patients, atrial flutter triggered shock therapy in 1 patient, and sinus tachycardia caused shock delivery in 2 patients. In 3 of the 13 patients inappropriate therapy recurred despite reprogramming the detection enhancements. The stability parameter of 241 spontaneous VT episodes as measured by the devices was 8 +/- 7 msec. Only 10 (4%) VTs had a stability parameter >25 msec. In 46 patients a combination of both detection enhancements, stability and/or sudden onset, were programmed. The use of detection enhancements proved safe and no patient had suffered negative side effects due to prolonged detection time or therapy delay. Inappropriate shock delivery due to AF, a major complication in ICD therapy, was reduced to 5% of patients. The use of the stability enhancement is recommended for patients with intermittent or chronic AF. Selected patients profit from programming both the stability and sudden onset criteria.

Adolescent↗

PubMed1996

[Pheochromocytoma-induced multiorgan failure. An internal medicine and surgical emergency].

HISTORY AND CLINICAL FINDINGS: A 66-year-old woman, for 18 months known to have a phaeochromocytoma of the left adrenal, developed sciatica-like pain, headaches, vomiting, diarrhoea and dyspnoea. She had previously refused operative treatment. Physical examination was largely negative. But within a few hours of admission she developed a fever (40.5 degrees C) as well as cardiopulmonary and renal failure. She had to be intubated. INVESTIGATIONS: There was leukocytosis (20,800/microliters) and an increase in creatine kinase activity (136 U/l), in the proportion of isoenzyme CKMB (19 U/l) and the creatine level (1.5 mg/dl). Coronary angiography excluded coronary heart disease. Compared with previous x-rays there was a definite increase in the space-occupying process in the area of the left adrenal. TREATMENT AND COURSE: The life-threatening state required emergency removal of the adrenal tumour. The operation was without complications, but muscle weakness set in, especially proximally, and was slow to regress. No cause was found. CONCLUSIONS: Primary manifestation of a phaeochromocytoma in the form of multiple organ failure is rare and its diagnosis is based on symptoms and radiological demonstration of the tumour, because biochemical data are obscured by the need to give catecholamines therapeutically. If the general condition deteriorates during conservative treatment immediate removal of the tumour is mandatory in view of the otherwise high death rate.

Adrenal Gland Neoplasms↗

PubMed1996

Improvement of exercise capacity with treatment of Cheyne-Stokes respiration in patients with congestive heart failure.

OBJECTIVES: The aim of this study was to determine the impact of nasal nocturnal oxygen therapy on respiration, sleep, exercise capacity, cognitive function and daytime symptoms in patients with congestive heart failure and Cheyne-Stokes respiration. BACKGROUND: Cheyne-Stokes respiration is common in patients with congestive heart failure and is associated with significant nocturnal oxygen desaturation and sleep disruption with arousals. Oxygen desaturations and arousals cause an increase in pulmonary artery pressure and sympathoneural activity and therefore may reduce exercise capacity. Oxygen is an effective treatment of Cheyne-Stokes respiration and should improve exercise capacity in these patients. METHODS: The study was designed as a randomized crossover, double-blind, placebo-controlled trial: 22 patients were assigned to 1 week each of nocturnal oxygen and room air. After each week, polysomnography, maximal bicycle exercise with expiratory gas analysis and trail-making test were performed, and a health assessment chart was completed. RESULTS: Nocturnal oxygen significantly reduced the duration of Cheyne-Stokes respiration (162 +/- 142 vs. 88 +/- 105 min [mean +/- SD]; p < 0.005). Sleep improved as evidenced by less stage 1 sleep and fewer arousals (20 +/- 13 vs. 15 +/- 9/h total sleep time; p < 0.05) as well as more stage 2 and slow-wave sleep; nocturnal oxygen saturation also improved. Peak oxygen consumption during exercise testing increased after oxygen treatment (835 +/- 395 vs. 960 +/- 389 ml/min; p < 0.05). Cognitive function evaluated by the trail-making test improved, but daytime symptoms in the health assessment chart did not improve significantly. CONCLUSIONS: Successful treatment of Cheyne-Stokes respiration with nocturnal nasal oxygen improves not only sleep, but also exercise tolerance and cognitive function in patients with congestive heart failure.

Adult↗

PubMed1996

Infective endocarditis in the elderly in the era of transesophageal echocardiography: clinical features and prognosis compared with younger patients.

PURPOSE: Advanced age is considered to be associated with a more severe prognosis in infective endocarditis (IE), which is relevance in view of a change in epidemiology of the disease with an increasing proportion of elderly people. We wanted to examine whether in the era of improved diagnostic sensitivity for IE by transesophageal echocardiography the clinical course in elderly persons would be still more severe than in younger patients. PATIENTS: During the period from 1989 to 1993, 104 patients with 106 episodes of IE were treated at our university hospital. Three groups were compared: group A with 28 patients younger than 50 years, group B with 58 patients aged 50 to 70, and group C with 20 patients older than 70. Transesophageal echocardiography was performed in 78% of the patients; it was not performed in 22% of the patients with a conclusive transthoracic examination. The patients were followed up for an average of 25 months after the diagnosis. RESULTS: No significant differences were observed among the age groups with respect to the possible source of infection, the frequency of positive blood cultures, and the type of infective organisms. Elderly patients more often had predisposing valvular conditions (eg, degenerative and calcified lesions and prosthetic valves), which decreased the sensitivity of transthoracic echocardiography to 45% as compared with 75% in group A. Transesophageal echocardiography improved the diagnostic yield by 45% in group C and by 47% in group B. Vegetations were smaller in group C and B as compared with group A, whereas other echocardiographic characteristics were similar. Fever and leukocytosis were less frequent in group C (55% and 25%, respectively) than in group A (82% and 61%, respectively). The interval between the onset of symptoms and the diagnosis of IE was similar in all groups. Elderly patients underwent surgical therapy as frequently (65%) as the other groups. The 1-year survival in group C (26%) was comparable with that in group A (22%) and group B (22%). The major determinant of survival was the occurrence of embolic complications. CONCLUSION: Infective endocarditis in elderly patients caused less severe clinical symptoms than in young patients. The early diagnosis in elderly patients was facilitated by the high sensitivity of transesophageal echocardiography, which enabled the timely initiation of an appropriate medical and surgical therapy. This led to a clinical outcome similar to that for younger patients.

Adolescent↗

PubMed1996

Changes in left ventricular filling during follow-up study in survivors and nonsurvivors of idiopathic dilated cardiomyopathy.

The assessment of left ventricular diastolic function by Doppler echocardiography shows both a nonrestrictive and restrictive type of filling in idiopathic dilated cardiomyopathy. These different filling patterns are related to the symptoms of cardiac failure and the prognosis. It remains to be established whether changes of Doppler parameters during follow-up procedures were of clinical relevance. Doppler echocardiography of left ventricular filling was done in 45 patients with idiopathic dilated cardiomyopathy at the time of their diagnosis and repeatedly during a follow-up study of 38 +/- 19 months. The deceleration time of early filling, the maximum early and atrial Doppler velocities and their ratios, as well as echocardiographic parameters of cardiac dimensions and systolic function, were measured. During the follow-up period, seven patients died and four patients underwent heart transplantation because of progressive heart failure. The deceleration time was shorter in patients who died or had to undergo heart transplantation as compared with survivors (119 +/- 43 ms vs 188 +/- 63 ms; P < .005). There was no difference in changes of clinical symptoms in survivors and nonsurvivors. The systolic function improved only in survivors. The difference in deceleration time remained significant between both groups, and it also remained a prognostic discriminator. Peak early velocity increased in nonsurvivors (from 0.66 +/- 0.20 m/s to 0.95 +/- 0.21 m/s; P < .01), while it remained constant in survivors (0.65 +/- 0.17 m/s and 0.67 +/- 0.25 m/s). The peak early/atrial velocity ratio varied widely in either group during the follow-up study, its changes were closely related to the concomitant changes of clinical symptoms (r = .59; P < .005) with a decrease of the peak early/atrial velocity ratio in patients with clinical improvement and an increase of the peak early/atrial velocity ratio in those without clinical improvement. The Doppler echocardiographic deceleration time discriminated between survivors and nonsurvivors in idiopathic dilated cardiomyopathy at the time of the initial diagnostic procedure, and this difference was persistent during the follow-up study. The serial evaluation of patients with idiopathic dilated cardiomyopathy showed a close association of changes in diastolic filling with changes in clinical symptoms.

Blood Flow Velocity↗

PubMed1996

Human corticotropin-releasing hormone and thyrotropin-releasing hormone modulate the hypercapnic ventilatory response in humans.

Human corticotropin-releasing hormone (hCRH) and thyrotropin-releasing hormone (TRH) are known to stimulate ventilation after i.v. administration in humans. In a placebo-controlled, single-blind study we aimed to clarify if both peptides act by altering central chemosensitivity. Two subsequent CO2-rebreathing tests were performed in healthy young volunteers. During the first test 0.9% NaCl was given i.v.; during the second test 200 micrograms of hCRH (n = 12) or 400 micrograms of TRH (n = 6) was administered i.v. Nine subjects received 0.9% NaCl i.v. during both rebreathing manoeuvres. The CO2-response curves for the two tests were compared within the same subject. In the hCRH group a marked parallel shift of the CO2-response curve to the left was observed after hCRH (P < 0.01). The same effect occurred following TRH but was less striking (P = 0.05). hCRH and TRH caused a reduction in the CO2 threshold. The CO2-response curves in the control group were nearly identical. The results indicate an additive effect of both releasing hormones on the hypercapnic ventilatory response in humans, presumably independent of central chemosensitivity.

Carbon Dioxide↗