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N Treese

Publications and source records attributed to N Treese.

At least 19 recordsLinked to original sources
PubMed2004

Reduction of the pace polarization artefact for capture detection applications by a tri-phasic stimulation pulse.

This study investigated the ability to minimize pace polarization artefacts (PPA) by adjusting the post-stimulus pulse duration of a tri-phasic stimulation pulse. Adjustment of the stimulation pulse was enabled by downloading special study software into an already implanted pacemaker. Tests were performed in a total of 296 atrial leads and 311 ventricular leads. Both chronic and acute leads were included in the study. Statistically significant differences were found in the initial PPA (without any adjustment of the stimulus pulse) between atrial and ventricular leads. In addition, significant differences were observed among various lead models with respect to changes over time in the initial ventricular PPA. Successful PPA reduction was defined as a reduction of the PPA below 0.5 mV for atrial leads and below 1 mV for ventricular leads. Results show a success rate for ventricular and atrial PPA reduction of 97.8% and 98.7%, respectively. Threshold tests showed that after reduction of the PPA loss of ventricular capture can be reliably detected. However, atrial threshold tests showed many false positive evoked response detections. In addition, unexpectedly high evoked response amplitudes were observed in the atrium after reduction of the PPA. Results from additional measurements suggest that these high atrial evoked response amplitudes come from the influence of the input filter of the pacemaker.

Aged↗
PubMed2000

MIC trial: metoprolol in patients with mild to moderate heart failure: effects on ventricular function and cardiopulmonary exercise testing.

UNLABELLED: Beta-blocker therapy results in a functional benefit in patients with heart failure (CHF) due to idiopathic dilated cardiomyopathy (DCM). This study assessed if similar effects were observed in patients with ischemic heart disease (CAD), NYHA II-III after 6 months of therapy with metoprolol. METHODS AND RESULTS: Fifty-two patients with CHF secondary to DCM (26 patients) and CAD (26 patients) and a left ventricular ejection fraction (EF)<40% were enrolled in the placebo-controlled study. The study medication was titrated over 6 weeks, the mean final dosage was 135 mg/day. Three patients died due to cardiogenic shock, two received placebo and one metoprolol. Eight patients did not complete the study due to non-compliance. Metoprolol significantly reduced heart rate at rest and after submaximal and maximal exercise. Vo(2)-max and Vo(2)-AT as well as the 6-min walk test improved significantly after metoprolol treatment. There was a significant increase in EF at rest (27.3-35. 2%), submaximal (28.5-37.7%) and maximal exercise (28.7-40.9%) in the metoprolol-treated patients. No differences were found between patients with CAD and DCM. We also observed reduced left ventricular volumes. CONCLUSION: The additional therapy with metoprolol improved cardiac function and the cardiopulmonary exercise capacity in patients with CHF.

Adrenergic beta-Antagonists↗
PubMed2000

Efficacy of single lead VDD pacing in patients with impaired and normal left ventricular function.

Atrial synchronous ventricular pacing seems to be the best pacing mode for patients with advanced AV block and impaired LV function. The long-term follow-up of single lead VDD pacing was studied in 33 patients with impaired LV function and compared to 42 patients with normal LV function. All patients received the same VDD lead and VDDR pacemaker. The lead model with 13-cm AV spacing between the atrial and ventricular electrode was implanted in 89% of the patients. Follow-ups were 1, 3, 6, and 12 months after implantation. The percentage of atrial sensing and the P wave amplitude were determined at each follow-up. Minimal P wave amplitude at implantation was 2.0 +/- 1.4 mV in patients with impaired and 1.7 +/- 0.9 mV with normal LV function (not significant). At the 12-month follow-up, 33 patients with normal and 23 patients with depressed LV function remained paced in the VDD mode. The remaining patients died in five (impaired LV function) and seven cases (normal LV function) or their pacemakers were programmed to the VVI/VVIR pacing mode in four (impaired LV function) and three cases (normal LV function). P wave amplitude did not differ in the two groups (e.g., at month 12: impaired: 1.17 +/- 0.42 mV; normal: 1.09 +/- 0.49 mV). The atrial sensitivity was programmed in most patients to sensitive settings with no differences between the two groups (e.g., at month 12: impaired: 0.13 +/- 0.06 mV; normal: 0.13 +/- 0.05 mV). The diagnostic counters indicated nearly permanent atrial sensing (e.g., at month 12: impaired: 99.3 +/- 2.2%; normal: 99.0 +/- 1.0 mV). In conclusions, single lead VDD pacing restored AV synchronous ventricular pacing in patients with normal and with impaired LV function indicating that it could be an alternative to DDD pacemakers, but not to dual-chamber pacing.

Aged↗
PubMed1999

[Medicamentous prevention after electric cardioversion of chronic atrial fibrillation. Goals and design of the PAFAC Study].

Atrial fibrillation (AF) is the most frequent cardiac arrhythmia. However, despite manifold publications reflecting numerous clinical trials about treatment of AF, the management of this arrhythmia is still under controversial discussion, in daily clinical work as well as in research. The present study concentrates on three major questions: 1. How frequent are recurrences of AF in long-term follow-up? Most of the previous studies used the occurrence of symptoms as a surrogate parameter for recurrences of AF, despite the expected high rate of asymptomatic relapses. In the present study a daily transtelephonic ECG transmission enables a rhythm monitoring independent of symptoms. 2. Is the frequency of AF recurrences significantly reduced by antiarrhythmic medication? A direct comparison of class I and III antiarrhythmic drugs, which still are most frequently used for this indication, and of placebo will answer this question. 3. How safe is the long-term treatment for the prevention of AF recurrences with special respect to proarrhythmic effects? The daily transtelephonic ECG transmission enables a quantitative and qualitative monitoring of tachy- and bradyarrhythmias independent of symptoms. Additionally, the daily analysis of ECG measures may detect parameters predicting subsequent life threatening arrhythmias. The study design provides a prospective, randomised, double-blind, placebo controlled, multicenter parallel group comparison. In Germany and in the Czech Republic about 90 hospitals will include 900 patients with documented chronic AF, age 18 to 80 years, if they are eligible for electrical cardioversion without concomitant antiarrhythmic drug therapy and if they are anticoagulated for at least three weeks prior to inclusion. Neither the size of the left atrium nor the duration of chronic AF are exclusion criteria. A few hours after successful electrical cardioversion the patients are randomised either to sotalol (2 x 160 mg) or quinidine + verapamil (3 x 160 mg + 3 x 80 mg) or placebo. Starting at the day after cardioversion, the patient is asked to record and transmit electrocardiograms of one minute duration at least once a day using his personal transtelephonic ECG recording unit (Tele-ECG recorder, credit card size), in case of symptoms as often as necessary. The ECGs can be transmitted at any time by any regular phone without additional equipment using a toll free number. A custom made, computer based, fully automated receiving centre is handling the patient calls interactively with voice control, including a voice recording of the patient's symptoms. The ECG tracings and the patient's voice messages are subsequently computer based analysed by experienced technicians. All ECG measures are stored in a database. In case of AF recurrence, any other relevant arrhythmia or additional abnormalities (e.g. QT prolongation) the correspondent hospital is immediately informed by fax. In case of AF recurrence, a subsequent Holter recording discriminates in paroxysmal and permanent AF. Study medication is ended if either permanent AF or the third episode of paroxysmal AF are detected or after 12 months of follow-up. Regular follow-up visits are performed monthly. Major endpoints are the time to first recurrence of AF or the time to death, secondary parameters are the number of AF recurrences, the time to end of medication and AF related symptoms. The recruitment started in the last days of 1996. Until the end of June 1998, 424 patients have been randomised. It is expected to end recruitment in spring 1999 and to close the study in spring 2000. Final results will be available in summer 2000.

Adolescent↗
PubMed1998

[The intraoperative measured stimulation impedance of pacemaker electrodes is not a predictor for their longevity].

UNLABELLED: As pacing impedance is inversely related to pacing current, the increase of pacing impedance additionally decreases pacing current. Whether the impedance measurement at implantation predicts the outcome during follow-up, was studied in 87 patients who received the VDD-single lead UniPass 425 connected to the pacemaker Unity (Sulzer Intermedics). The impedance changes between implantation and 6 months follow-up were assessed for each patient. Similar impedance values were defined, if the two measurements were within a range < or = -100 to +100 omega. Six-months impedance was lower or higher compared to implantation, if the difference exceeded > -100 or > +100 omega. At implantation, impedance was 535 +/- 98 omega (range: 333-811 omega) and significantly increased to 604 +/- 160 omega (range: 361-1150 omega) after 6 months. Mean difference between the two measurements was 69 +/- 162 omega (range: -336 bis + 560 omega). Similar impedance had 43 (implantation: 527 +/- 75 omega, 6 months: 531 +/- 87 omega), lower values 11 (implantation: 660 +/- 83 omega, 6 months: 494 +/- 73 omega) and higher values 33 patients (implantation: 503 +/- 99 omega, 6 months: 735 +/- 168 omega). Compared to the patients with similar impedance patients with lower impedance had a significantly higher impedance values at implantation. CONCLUSIONS: Pacing impedance increased significantly within 6 months after implantation. Pacing impedance changed > 100 omega in 51% of the patients. The long-term follow-up of pacing impedance can be predicted generally, but not for the individual patient.

Aged↗
PubMed1998

[Prognostic significance of analysis of heart rate variability inpatients with dilated cardiomyopathy].

UNLABELLED: Sudden cardiac death is frequent in patients with dilated cardiomyopathy. To assess the risk of an arrhythmic event is still difficult. Here the analysis of the heart rate variability offers new possibilities. METHOD: 25 patients (18 males, 7 females, age 53 +/- 9 yrs) with dilated cardiomyopathy were included in the study. Analysis of heart rate variability assessed by time- and frequency-domain measures was determined from Holter recording. The mean follow-up was 18 +/- 5 months. RESULTS: 6 patients died (5 of sudden cardiac death, 1 of heart failure), 1 patient with an implanted defibrillator received an adequate shock. Parameters influenced by low- and mid-frequent oscillations of the heart rate were significantly lower in patients who died suddenly or had adequate shocks. The best predictive parameter was the s.d.RR: all patients with an s.d.RR < 50 ms had lethal arrhythmias whereas the s.d.RR of the surviving patients was > or = 50 ms. No significant difference was found or high frequency parameters, which are mainly influenced by parasympathetic activity. CONCLUSION: The analysis of heart rate variability is of prognostic relevance in patients with dilated cardiomyopathy. Especially the s.d.RR is able to identify patients with a high risk of a sudden cardiac death.

Adult↗
PubMed1997

[The effect of a lower stimulation frequency on the AV synchronicity of VDD pacemakers].

BACKGROUND AND OBJECTIVE: Implantation of a VDD pacemaker (ventricular pacing; dual sensing [atrial and ventricular]; dual response [triggered + inhibited]) together with a single VDD electrode catheter restores synchronous AV ventricular stimulation in patients with higher-grade AV block and intact sinus function. If higher-frequency stimulation occurs it may be a sign of pacemaker malfunction or of inadequate pacemaker programming. This study was undertaken to determine, at first follow-up examination, in how many patients with a VDD pacemaker VVI stimulation occurred more than 5% of the time; how such patients differed from those with 5% or fewer VVI stimulations; and whether a changed program reduced the proportion of VVI stimulations. PATIENTS AND METHODS: 67 consecutive patients were tested 1 to 3 months after implantation of the Unity VDD pacemaker (Sulzer Intermedics). The frequency of VVI stimulations was determined via a diagnostic pacemaker memory store. After intermediate analysis, programming was optimized and the patients then re-tested 12 months after the initial implantation. RESULTS: At the first follow-up examination 54 patients had VVI stimulations of < or = 5% (0.5 +/- 0.9%) and 13 had > 5% of the time (19.8 +/- 10.7%). The two groups differed significantly from one another in their lower intervention frequency (< or = 5% VVI stimulations: 47 +/- 6/min; > 5% VVI stimulations: 58 +/- 5/min). In particular, the pacemakers in patients with > 5% VVI stimulations had been significantly more often programmed to values of > 50/min. As a result, the pacemakers of these patients were reprogrammed to a lower frequency. A year after implantation there was no longer any difference in the lower intervention frequency, 44 +/- 4/min, between patients with initially > 5% VVI stimulations and those with initially < or = 5% stimulations. At the same time, the proportion of VVI stimulations fell to 4 +/- 6%, with 67% of patients having AV synchronicity of > 95%. INTERPRETATION: At first follow-up, patients with > 5% VVI stimulations differed from those with < or = 5% stimulations with regard to an increased lower intervention frequency. In most of these patients the proportion of AV stimulations was increased to > 95% by reducing the lower intervention frequency to < or = 50/min.

Aged↗
PubMed1997

[Status of digitalis in therapy of acute and chronic heart failure].

Although supported by more than 200 years of experience and anecdotal clinical evidence, the efficacy of digitalis in the management of heart failure has been questioned until the past decade. The idea to improve contractility of the diseased myocardium with an inotropic agent is fundamental in the management of left ventricular dysfunction. The majority of clinical trials published since 1980, most of which examined patients with mild to moderate heart failure, indicate that digitalis alone or in combination with vasodilators may improve the clinical outcome particular in those patients with more advanced symptoms and poorer left ventricular function. Aside from its action as an inotropic drug the pharmacology and the mechanisms by which digitalis influence the diseased myocardium and peripheral circulation in heart failure has gained more complexity within the last years, raising the idea of other mechanisms that might be involved in its action. Particular for ACE inhibition multiple clinical trials have conclusively demonstrated its impact on survival and morbidity in congestive heart failure. Improvement of clinical outcome as measured in terms of fewer hospitalizations and improvement of symptoms in patients receiving digitalis seems to be comparable to patients receiving beta-blockers additional to diuretics and ACE inhibitors, an entirely different approach to the treatment of heart failure. Despite initial improvement of hemodynamics it now appears that there is no survival benefit found for digitalis in the management of heart failure.

Acute Disease↗
PubMed1997

Feasibility and sensing thresholds of temporary single-lead VDD pacing in intensive care.

Long-term pacemaker treatment of patients with a high-degree atrioventricular (AV) block routinely uses AV synchronous pacing because of its hemodynamic advantages compared with VVI pacing. In cases of temporary pacing, however, the limitations inherent in attempting to reliably position a temporary atrial lead generally influences the use of VVI pacing. We therefore tested the use of temporary single-lead VDD pacing, making AV pacing possible with only 1 lead, in 22 patients requiring temporary pacing due to a high-degree AV block. AV synchronous stimulation was achieved in all patients using a quadripolar lead with an atrial dipole with the atrial rings spaced 30 mm apart. During follow-up (14.1 +/- 12.5 hours) intermittent undersensing was detected in 4 of the 22 patients. We initially evaluated the atrial sensing threshold by decreasing the pacemaker device sensitivity stepwise in all patients (1.54 +/- 1.08 mV; n = 22). In 15 patients an intra-atrial electrocardiogram was recorded. During the breathing cycle, the maximum P-wave amplitude was significantly different from the minimum P-wave amplitude (2.19 +/- 1.00 mV vs 1.25 +/- 0.65 mV, p < 0.005). The atrial signal detected by the single lead was further analyzed in 10 of 15 patients using various filters. A mean signal loss of 45% was observed, increasing the lower bandpass frequency from 0.1 to 40 Hz (1.73 +/- 0.71 mV vs 0.92 +/- 0.51 mV, p < 0.02). Lowering the upper filter range from 1,000 Hz down to 100 Hz did not significantly influence the atrial signal (1.73 +/- 0.71 mV vs 1.61 +/- 0.75 mV, NS). Single-lead VDD pacing, even on a temporary basis, is a reliable means of achieving AV synchronous pacing. Due to the floating atrial dipole, the system is characterized by a high degree of variability in the atrial signal with intermittent lower values. A significant signal loss must be expected when a lower bandpass frequency of 40 Hz is used.

Aged↗
PubMed1997

[Late potentials in the diagnosis of post-infarction patients: arrhythmogenic risk and clinical symptomatology].

A prospective study was performed of the correlation of ventricular late potentials (LP) and clinical parameters in patients after acute myocardial infarction. To evaluate the prognostic significance of the signal-averaged-electrocardiogram (SAECG) in risk stratification of sudden cardiac death and arrhythmogenic events, the clinical characteristics of these post-infarction patients were performed in a follow-up-period. 243 consecutive patients underwent SAECG for detection of late potentials in the second week after acute myocardial infarction. After a mean follow-up of 9 months the patients were asked a standardized questionnaire. Late potentials are independent of age, sex, left ventricular ejection fraction, peak activity of MB fraction of creatine kinase, and the cardiovascular risk factors in postinfarction patients. In patients, who received thrombolytic therapy, the incidence of late potentials is lower (p < 0.05) and in patients with posterior wall infarction it is significantly higher (p < 0.04). In the follow-up period patients with abnormal SAECG show a significantly higher rate of angina pectoris, palpitations, dizziness, and syncope. By way of contrast, postinfarction patients with normal SAECG feel mainly comfortable in the follow-up (p < 0.01). The mortality was even in both groups. Sudden cardiac death in the late postinfarction period shows a significant correlation with the finding of late potentials in SAECG in the early myocardial infarction period (p < 0.01). The SAECG for detection of late potentials as a non-invasive investigation in the early postinfarction period characterizes patients with an arrhythmogenic risk, especially sudden cardiac death, independent of other conventional methods. Furthermore, the impaired patient with clinical symptoms in the late postinfarction period is hereby identified.

Action Potentials↗
PubMed1997

Efficacy of a new prostaglandin E1 regimen in outpatients with severe intermittent claudication: results of a multicenter placebo-controlled double-blind trial.

For the first time efficacy and safety of a new prostaglandin E1 (PGE1) regimen in the treatment of intermittent claudication were evaluated in a randomized, double-blind, placebo-controlled multicenter clinical trial. The study involved 213 outpatients with a maximum walking distance of 50 to 200 m measured on the treadmill (3 km/hr, 12% grade). After a 2-week run-in phase they received a 2-hour intravenous infusion of 60 micrograms PGE1 or placebo 5 days a week for 4 weeks. It was followed by a 4-week interval treatment with the same medication administered only twice a week. Patients were monitored for 3 months when they received no study medication. In the PGE1 group the intention-to-treat analysis (n = 208) revealed an increase in walking distance after 4 weeks of 75% (placebo, 43%). At the end of the interval treatment the walking distance had improved to 101% (placebo, 60%). The results remained virtually constant during follow-up (PGE1, 104%, placebo, 63%). Between-group comparisons showed significant differences in favor of PGE1 for all three time points of measurement (p < 0.05, p < 0.01, and p < 0.05). PGE1 was well tolerated; the rate of adverse reactions related to the treatment was 12.8% (placebo, 7.7%). In summary, these results show that the new PGE1 regimen is effective and safe in the treatment of outpatients with intermittent claudication.

Aged↗
PubMed1996

Impaired cardiopulmonary exercise capacity in patients with hyperthyroidism.

STUDY OBJECTIVE: Hyperthyroidism (H) has been implicated as a primary cause of decreased exercise tolerance. To our knowledge, analysis of respiratory gas exchange, an efficient noninvasive method in evaluating cardiopulmonary capacity, has not been performed in patients with H. PATIENTS: Using cardiopulmonary exercise testing, 12 consecutive women with Graves' H were examined and controlled in euthyroidism (E). Eighteen women with E, in whom cardiac catheterization had ruled out heart disease, served as control subjects (C). MEASUREMENTS: The ventilatory anaerobic threshold was determined by means of the V-slope method. Ergometry was performed with patients in a semisupine position using a continuous ramp protocol of 20 W/min. Echocardiography at rest was performed in all patients. RESULTS: In patients with H, heart rate at rest was higher than in patients with E (p < 0.05) and showed a markedly lower increase between rest and anaerobic threshold compared with E patients (p = 0.007) and C (p = 0.009). Work rate was reduced (H, 50% vs E, 70%; p = 0.038). In H patients, the anaerobic threshold occurred at 59.6% of maximal oxygen uptake and 72% in E patients, respectively (p = 0.024). In H patients, the linear regression of the heart rate to oxygen uptake ratio showed a reduced slope in comparison with E patients (p = 0.001) and C (p = 0.004). In patients with H, a reduced tidal volume (p = 0.021) and an increased respiratory rate (p = 0.003) in comparison to patients with E were demonstrated. Echocardiographically, H patients had an increased ejection fraction (p = 0.008) and a higher cardiac index (p = 0.008) in comparison with E patients. CONCLUSIONS: Analysis of respiratory gas exchange showed marked alterations of cardiopulmonary exercise capacity in H patients, which are reversible in E patients. The impaired chronotropic response during exercise might be the primary limiting factor of reduced work capacity in patients with H.

Adult↗
PubMed1996

[DDD versus DDDR pacemaker stimulation: comparison of cardiopulmonary performance, incidence of atrial arrhythmias and quality of life].

The purpose of this study was to assess cardiopulmonary exercise capacity, variation in heart rate during everyday activities, frequency of atrial arrhythmias and quality-of-life during accelerometer-based rate modulated dual-chamber pacing. Nine chronotropically incompetent and 14 chronotropically competent patients (mean age 51 years) were randomly assigned to DDD and DDDR mode and evaluated by a semisupine bicycle exercise testing exceeding the anaerobic threshold, 24-h Holter monitoring and a quality-of-life questionnaire. In the subgroup of patients with chronotropic incompetence, defined by a HR/VO2-ration, 2 beats/ml/kg, during DDDR pacing, compared to DDD, maximum heart rate increased from 83 +/- 13 to 132 +/- 7 beats/min (p < 0.01), maximum oxygen uptake from 12.7 +/- 3.1 to 15.3 +/- 3.2 ml/kg/min ( p < 0.05) and the VO2/WR-ratio from 8.1 +/- 1.0 to 9.0 +/- 0.9 ml/min/watts (p < 0.05). Exercise duration lengthened from 252 +/- 59 to 301 +/- 96 s (p < 0.05). During the 24-h Holter recordings the average maximum heart rate rose form 69 +/- 7 in the DDD mode to 78 +/- 9 beats/min in the DDDR mode significantly (p < 0.05). DDDR pacing did not result in an increased number of atrial salvos (2.6 atrial events/24 h) when compared to DDD pacing (2.5 atrial events/24 h, N.S.). These objective results were confirmed by the quality-of life assessment due to a symptom questionnaire. The symptom score declined from 20 +/- 10 in the DDD mode to 16 +/- 7 in the DDDR mode (p < 0.01). In the patients with chronotropic competence, however, cardiopulmonary exercise capacity did not improve in the DDDR mode: maximum heart rate was 120 +/- 21 versus 130 +/- 24 beats/min (N.S.), maximum oxygen uptake 17.7 +/- 5.9 versus 16.8 +/- 5.9 ml/kg/min (N.S.), The VO2/WR-ratio 9.8 +/- 2.3 versus 9.2 +/- 2.5 ml/min/watts (N.S.) and the exercise duration 407 +/- 159 versus 406 +/- 165 s (N.S.). The average maximum heart rate was 80 +/- 15 in the DDD mode and 83 +/- 16 beats/min in the DDDR mode (N.S.). Significantly more atrial arrhythmias occurred in the DDDR pacing mode: 1.6 atrial salvos per 24 h in the DDD mode versus 4.8 atrial salvos per 24 h in the DDDR mode (p < 0.05). This patient subgroup experienced a significant worsening of his quality-of-life. The symptom score rose from 20 +/- 9 in the DDD mode to 28 +/- 11 in the DDDR mode (p < 0.05). In conclusion, DDDR pacing improved cardiopulmonary exercise capacity, normalized heart rate variation over 24 h and increased quality-of-life in patients with chronotropic incompetence. On the contrary, since the DDDR pacing more could not improve cardiopulmonary exercise capacity, increased atrial arrhythmias and worsened the patient's quality-of-life, patients with chronotropic competence should not be programmed in the DDDR pacing mode.

Adolescent↗
PubMed1996

[Comparison of NYHA classification with cardiopulmonary function in patients with chronic heart failure].

In this study a correlation was sought between the NYHA class, the results of cardiopulmonary exercise testing (CPX) and the ejection fraction (EF) measured by echocardiography and scintigraphy. Of 36 patients enrolled, CHF in 20 patients was due to CAD and in 16 patients due to DCM. The NYHA class was determined independently by two cardiologists who were blinded to the CPX, echocardiography or scintigraphy results. Sixteen patients were classified as class II and 20 as class III. As a control, 23 patients without cardiopulmonary disease were examined. The CPX was done according to a ramp protocol with continuous measurement of respiratory gases, maximal oxygen consumption (VO2-max) and oxygen consumption at the anaerobic threshold (VO2-AT). A correlation (p = 0.0425) between the NYHA classification and the Weber classification for VO2-AT was found. There was no correlation for VO2-max. VO2-AT was significantly higher in NYHA II patients as compared to NYHA III patients. No significant difference was seen in relation to the VO2-max. In comparison to the normal group, the VO2-AT and VO2-max were significantly lower in NYHA II and III patients. There was no significant correlation between VO2-AT and EF, VO2-max and EF, or between NYHA class and EF. During a 16-month follow-up period lethality was 8/14 patients with VO2-AT < 10 ml/kg/min. Although the NYHA classification provides a valid method for determining the prognosis of CHF patients, if feasible, the CPX examinations should be used to provide updates of the disease progress.

Adult↗
PubMed1995

Cardiac output in single-lead VDD pacing versus rate-matched VVIR pacing.

The importance of atrioventricular synchronous pacing compared with single-chamber rate-responsive pacing is still under discussion, especially for low-intensity workload representing daily life activities. We evaluated hemodynamics in single-lead VDD pacing versus VVIR pacing in 11 patients (8 men and 3 women, aged 58.6 +/- 13.8 years) with normal left ventricular function and a previously implanted single-lead VDDR pacemaker. A low-intensity steady-state treadmill test at 1 to 2.5 mph with a gradient of 2% to 4% was performed. Cardiac output was determined using a standard carbon dioxide rebreathing technique. Initially, the VDD mode was programmed, and after 5 minutes of exercise, cardiac output was measured in steady-state conditions. The pacemaker was then reprogrammed to the VVI mode at a rate 5 to 10 beats above the maximal atrial tracking rate to simulate rate-matched VVIR pacing (VVIRm). After 5 additional minutes of steady-state exercise, cardiac output was measured again. The maximal atrial rate in the VDD mode was 119 +/- 19 beats/min versus a programmed rate of 129 +/- 18 beats/min in the VVIRm mode. VDD pacing resulted in a significantly higher cardiac output than VVIRm pacing (10.6 +/- 1.9 vs 9.2 +/- 1.4 L/min; p < 0.002), with a mean difference of 1.6 +/- 1.2 L/min between the 2 modes. In the VDD mode, stroke volume (90.7 +/- 20.1 vs 71.6 +/- 13.0 ml; p < 0.001) and maximal oxygen uptake (1,183 +/- 264 vs 1,076 +/- 289 ml/min, p < 0.01) were also higher than in VVIRm.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

[Atrial sensing by a new VDD pacemaker].

VDD stimulation is an alternative to DDD pacing due to the possibility of p-wave synchronous ventricular pacing without the need of an atrial lead. Mainly, the reliability of the system depends on the atrial sensing. In 22 patients the intraoperative atrial amplitude and, postoperatively, the atrial sensing threshold were measured. Furthermore, the stability of the atrial sensing threshold during follow-up was proven. The mean atrial amplitude was intraoperative by 2.4 +/- 1.2 (1.0-6.8) mV. The measurement of the atrial sensing threshold in the first 5 postoperative days showed a mean value of 1.02 +/- 0.49 (0.3-1.6) mV. The measurements of the mean atrial sensing threshold after 30, 90, and 180 days showed no statistical differences. Intraindividual variance was shown in 17/20 patients (0.55 +/- 0,42; 0.15-1.05 mV). Seventeen of the 22 patients were programmed with an atrial sensing threshold of 0.3 mV. In five patients the atrial sensing threshold was programmed at less than 0.3 mV in order to reach a twofold atrial sensitivity. Despite a programmed atrial sensitivity of 0.1 mV and isometric conditions no atrial oversensing occurred. The postoperative atrial sensing thresholds of the VDD system investigated were significantly lower than the intraoperatively measured atrial amplitudes. The mean atrial sensing threshold did not change during the follow-up period. The variation which did occur was within individual variation at different return visits.

Aged↗
PubMed1995

[Cardiovascular parameters in transient hypothyroidism].

Cardiovascular manifestations are a frequent finding in hypothyroidism. Thus, blood-pressure measurements, longtime electrographic monitoring, and spiroergometry were examined in 20 patients with transitory hypothyroidism. In the patients with thyroid carcinoma, total thyroidectomy was performed. Measurements were made in hypothyroidism and after TSH-suppression with L-thyroxine. Thirty-five patients in whom intracardiac catheter examination ruled out cardiopulmonary disease served as controls. Cardiopulmonary exercise was done by bicycle exercise testing. In transitory hypothyroidism an increase of diastolic blood pressure was found at rest (p = 0.02) and during exercise (p = 0.002), which was reversible after T4-therapy. Compared to the controls diastolic blood pressure in hypothyroidism was increased at rest (p = 0.014) and during exercise (p = 0.005). ECG-monitoring showed a day-night difference in heart rate in hypothyroid patients and after therapy. The mean heart rate (74 vs. 88 beats per minute; p = 0.0006), the minimal (p = 0.0062) and the maximal heart rate (p = 0.0016) during the day were decreased in hypothyroidism compared to euthyroidism. There were no atrioventricular blocks in transitory hypothyroidism and no increase of ventricular or supraventricular premature beats after high-dose T4-treatment. Spiroergometry showed no change in ventilation and an increased growth in heart rate (p = 0.021) associated with good working capacity in hypothyroid patients. Heart rate at rest (p = 0.004) and at the anaerobic threshold (p = 0.03) were decreased in transitory hypothyroidism.

Adult↗