PubMed Health⌕ Search

Biomedical subjects

P Ritter

Publications and source records attributed to P Ritter.

At least 19 recordsLinked to original sources
PubMed2003

Echocardiographic modeling of cardiac dyssynchrony before and during multisite stimulation: a prospective study.

Multisite biventricular pacing therapy offers significant clinical improvement in some stimulated patients with electrocardiographic criteria of cardiac dyssynchrony. However, observational data increasingly suggest that patients suffering from congestive heart failure in presence of modest QRS widening may also derive benefit from cardiac resynchronization therapy (CRT), and that some patients can be significantly improved clinically after system implantation despite no apparent change in QRS width. This pilot study explored the value of an echocardiographic model to identify cardiac electromechanical dyssynchrony parameters (EDP) in candidates for CRT, and their potential correction after implantation. The study included 66 consecutive CRT recipients of CRT in NYHA functional class III or IV who had one or more atrioventricular, interventricular or intraventricular dyssynchrony criteria. An immediate improvement was observed in 85% of the population with a partial or total correction of their EDP. However, the modifications in EDP differed considerably between recipients of de novo CRT systems and patients with previously implanted standard pacing systems upgraded with the implantation of a left ventricular lead. EDP measurements appear to identify potential candidates for CRT, and to confirm the success of system implantation.

Atrioventricular Node↗
PubMed2003

[Which pacemaker for which patient].

Once the indication for permanent cardiac pacing has been retained, the problem is to determine the choice of pacemaker. The choice of model is based on a clear understanding of the physiology of cardiac pacing, a subject which has been completed by the introduction of cardiac resynchronisation in 1994, reserved for patients with cardiac failure resistant to maximal medical therapy and who have desynchronisation of ventricular contraction. Another problem is the choice of the most appropriate model of all commercially available devices adapted to the individual patient's condition. It goes without question that an implanted pacemaker should be optimally programmed for each patient.

Arrhythmias, Cardiac↗
PubMed2003

[Echocardiographic modelling of cardiac asynchronism: prospective evaluation before and after multisite stimulation].

The evaluation of multisite stimulation with a haemodynamic aim has since its origin clashed with the absence of definition of a simple method of identifying candidates and of evaluation of the effects of treatment. In this pilot work, 66 patients were selected on electromechanical criteria obtained from a desynchronisation model identified from simple echographic parameters. The short term results demonstrate important modifications, differing according to the type of patient undergoing implantation. These results reject the basis of a prospective multicentric study aimed at validating the concept of ventricular resynchronisation.

Arrhythmias, Cardiac↗
PubMed2002

Comparative effects of permanent biventricular and right-univentricular pacing in heart failure patients with chronic atrial fibrillation.

BACKGROUND: One third of chronic heart failure patients have major intraventricular conduction and uncoordinated ventricular contraction. Non-controlled studies suggest that biventricular pacing may improve haemodynamics and well-being by reducing ventricular asynchrony. The aim of this trial was to assess the clinical efficacy and safety of this new therapy in patients with chronic atrial fibrillation. METHODS: Fifty nine NYHA class III patients with left ventricular systolic dysfunction, chronic atrial fibrillation, slow ventricular rate necessitating permanent ventricular pacing, and a wide QRS complex (paced width >or=200 ms), were implanted with transvenous biventricular-VVIR pacemakers. This single-blind, randomized, controlled, crossover study compared the patients' parameters, as monitored during two 3-month treatment periods of conventional right-univentricular vs biventricular pacing. The primary end-point was the 6-min walked distance, secondary end-points were peak oxygen uptake, quality-of-life, hospitalizations, patients' preferred study period and mortality. RESULTS: Because of a higher than expected drop-out rate (42%), only 37 patients completed both crossover phases. In the intention-to-treat analysis, we did not observe a significant difference. However, in the patients with effective therapy the mean walked distance increased by 9.3% with biventricular pacing (374+/-108 vs 342+/-103 m in univentricular;P =0.05). Peak oxygen uptake increased by 13% (P=0.04). Hospitalizations decreased by 70% and 85% of the patients preferred the biventricular pacing period (P<0.001). CONCLUSION: As compared with conventional VVIR pacing, effective biventricular pacing seems to improve exercise tolerance in NYHA class III heart failure patients with chronic atrial fibrillation and wide paced-QRS complexes. Further randomized controlled studies are required to definitively validate this therapy in such patients.

Aged↗
PubMed2001

International Child Care Practices Study: infant sleeping environment.

BACKGROUND: The International Child Care Practices Study (ICCPS) has collected descriptive data from 21 centres in 17 countries. In this report, data are presented on the infant sleeping environment with the main focus being sudden infant death syndrome (SIDS) risk factors (bedsharing and infant using a pillow) and protective factors (infant sharing a room with adult) that are not yet well established in the literature. METHODS: Using a standardised protocol, parents of infants were surveyed at birth by interview and at 3 months of age mainly by postal questionnaire. Centres were grouped according to geographic location. Also indicated was the level of SIDS awareness in the community, i.e. whether any campaigns or messages to "reduce the risks of SIDS" were available at the time of the survey. RESULTS: Birth interview data were available for 5488 individual families and 4656 (85%) returned questionnaires at 3 months. Rates of bedsharing varied considerably (2-88%) and it appeared to be more common in the samples with a lower awareness of SIDS, but not necessarily a high SIDS rate. Countries with higher rates of bedsharing appeared to have a greater proportion of infants bedsharing for a longer duration (>5 h). Rates of room sharing varied (58-100%) with some of the lowest rates noted in centres with a higher awareness of SIDS. Rates of pillow use ranged from 4% to 95%. CONCLUSIONS: It is likely that methods of bedsharing differ cross-culturally, and although further details were sought on different bedsharing practices, it was not possible to build up a composite picture of "typical" bedsharing practices in these different communities. These data highlight interesting patterns in child care in these diverse populations. Although these results should not be used to imply that any particular child care practice either increases or decreases the risk of SIDS, these findings should help to inject caution into the process of developing SIDS prevention campaigns for non-Western cultures.

Beds↗
PubMed2001

Estrogen sulfamates: a new approach to oral estrogen therapy.

Sulfamate substitution (-O-SO2-NH2) at carbon atom 3 of the steroid skeleton leads to orally active prodrugs of estrogens with much higher systemic, but lower hepatic, estrogenic activity than their parent steroids. This dissociation is achieved by first passage through the liver in erythrocytes, followed by systemic hydrolysis which releases the 'parent' estrogen. In the rat, orally administered tritiated estradiol sulfamate, unlike estradiol, appears in the circulation at high concentrations. At Cmax, approximately one third of the administered dose forms a depot in the circulation (98% in erythrocytes, 2% in plasma). Significant estradiol, estrone and estrone sulfate concentrations were recorded in plasma during depletion of the red blood cell pool. Estradiol sulfamate (J995) has no estrogen receptor affinity per se or estrogenic activity in vitro ( i.e. without hydrolysis). Its oral uterotropic activity in rats is approximately 100 times greater than that of estradiol, however, its hepatotropic activity is only marginally elevated. These functions include bile secretion, the secretion of angiotensinogen, lipoproteins (total and high-density lipoprotein cholesterol) and insulin-like growth factor I (IGF-I). Orally administred estradiol sulfamate led to systemic estrogenic effects without significant hepatic responses, whereas estradiol and other 'conventional' estrogens exerted parallel systemic and hepatic estrogenic effects. Sulfamate technology represents an approach to the use of natural estrogens for fertility control and hormone replacement therapy in both genders. In this context, reduced effects on hemostatic factors, angiotensinogen, bile and IGF-I secretion seem the most important aspects. In addition, blood concentrations of estrogens are less variable than with conventional estrogens.

Administration, Oral↗
PubMed2001

Physical activity outcomes of CHAMPS II: a physical activity promotion program for older adults.

BACKGROUND: Despite well-known benefits of physical activity for older adults, about two thirds are underactive. Community-based programs are needed to facilitate increased physical activity. We examine the effectiveness of CHAMPS II, an inclusive, choice-based physical activity promotion program to increase lifetime physical activity levels of seniors. CHAMPS guided participants to choose activities that took into account their health, preferences, and abilities. It offered information on ways for them to exercise safely, motivate themselves, overcome barriers, and develop a balanced exercise regimen. METHODS: A 1-year randomized controlled trial was conducted with physically underactive seniors in a multispecialty group practice. Changes in self-reported physical activity by group were evaluated using ANCOVA, controlling for age and sex. RESULTS: Of 173 randomized subjects, 164 (95%) completed the trial. Subjects were aged 65 to 90 years (M = 74, SD = 6); 66% were female. The intervention group increased estimated caloric expenditure by 487 calories/week in moderate (or greater) intensity activities (MET >/= 3.0; p <.001) and by 687 calories/week in physical activities of any intensity (p <.001). Control group changes were negligible. Between-group analyses found that the changes were significantly different in both measures (p values <.05). Overweight persons especially benefited from this program. The program was as effective for women, older adults (75+), and those who did not set aside time to exercise at baseline. CONCLUSIONS: The program led to meaningful physical activity increases. Individually tailored programs to encourage lifestyle changes in seniors may be effective and applicable to health care and community settings.

Aged↗
PubMed2001

Chronic disease self-management program: 2-year health status and health care utilization outcomes.

OBJECTIVES: To assess the 1- and 2-year health status, health care utilization and self-efficacy outcomes for the Chronic Disease Self-Management Program (CDSMP). The major hypothesis is that during the 2-year period CDSMP participants will experience improvements or less deterioration than expected in health status and reductions in health care utilization. DESIGN: Longitudinal design as follow-up to a randomized trial. SETTING: Community. PARTICIPANTS: Eight hundred thirty-one participants 40 years and older with heart disease, lung disease, stroke, or arthritis participated in the CDSMP. At 1- and 2-year intervals respectively 82% and 76% of eligible participants completed data. MAIN OUTCOME MEASURES: Health status (self-rated health, disability, social/role activities limitations, energy/fatigue, and health distress), health care utilization (ER/outpatient visits, times hospitalized, and days in hospital), and perceived self-efficacy were measured. MAIN RESULTS: Compared with baseline for each of the 2 years, ER/outpatient visits and health distress were reduced (P <0.05). Self-efficacy improved (P <0.05). The rate of increase is that which is expected in 1 year. There were no other significant changes. CONCLUSIONS: A low-cost program for promoting health self-management can improve elements of health status while reducing health care costs in populations with diverse chronic diseases.

Adult↗
PubMed2000

Atrioventricular interval optimization in the right atrial appendage and interatrial septum pacing: a comparison between echo and peak endocardial acceleration measurements.

Interatrial septum pacing (IASP) reduces interatrial conduction time and consequently may interfere with atrioventricular delay (AVD) optimization. We studied 14 patients with an implanted BEST Living system device able to measure peak endocardial acceleration (PEA) signal. The aims of our study were to compare the (1) optimal AVD (OAVD) in right atrial appendage pacing (RAAP) and IASP, and (2) OAVD derived by the PEA signal versus OAVD derived by Echo/Doppler evaluation of the left ventricular filling time (LVFT) and cardiac output (CO). Measurements were performed in DDD VDD modes Eight patients (group A) had RAAP and six patients (group B) had IASP. In group A, OAVD measured by LVFT, CO, and PEA was 185 +/- 23 ms, 177 +/- 19 ms, and 192 +/- 23 ms in DDD and 147 +/- 19 ms, 135 +/- 27 ms, and 146 +/- 20 ms in VDD, respectively. OAVD measured by LVFT, CO, and PEA was significantly longer in DDD mode than in VDD (P < 0.01, P < 0.01, P < 0.001). In group B, OAVD measured by LVFT, CO, and PEA was 116 +/- 19 ms, 113 +/- 10 ms, and 130 +/- 30 ms in DDD and 106 +/- 16 ms, 96 +/- 15 ms, and 108 +/- 26 ms in VDD, respectively. No statistical differences were observed between DDD and VDD. Significant correlations between OAVDs PEA derived and OAVDs LVFT and CO derived were observed (r = 0.71, r = 0.69, respectively). When new techniques of atrial stimulation, as IASP, are used an OAVD shorter and similar in VDD and DDD has to be considered. The BEST Living system could provide a valid method to ensure, in every moment, the exact required OAVD to maximize atrial contribution to CO.

Atrial Appendage↗
PubMed2000

Continuous monitoring of an endocardial index of myocardial contractility during head-up tilt test.

BACKGROUND: Previous studies suggest that vigorous myocardial contractions stimulate ventricular mechanoreceptors and lead to vasovagal syncope. We studied an endocardial index of myocardial contractility during the head-up tilt test in vasovagal patients and control patients, and we evaluated the effect of negative inotropic drugs on myocardial contractility and tilt test outcome. METHODS AND RESULTS: We investigated 19 patients with recurrent vasovagal syncope and positive tilt test (group 1) and 11 patients with no syncope and negative tilt test (group 2). Myocardial contractility was continuously measured during a tilt test (60 degrees ) through a microaccelerometer incorporated in the tip of a right ventricular electrode to sense left ventricular contractility. Patients in groups 1 and 2 were evaluated during an unmedicated tilt test, and patients in group 1 were reevaluated during a tilt test with infusion of esmolol (n = 10) or disopyramide (n = 9). During the unmedicated test, patients in group 1 exhibited a significant increase in myocardial contractility immediately on postural change (P <.05), unlike patients in group 2. Patients in group 1 also had a further increase in myocardial contractility before the end of tilt (P <.01). With drug administration, the changes in supine myocardial contractility were nonsignificant and were not related with the outcome of the tilt test (P <.05). CONCLUSIONS: An increase in myocardial contractility is detected by the sensor during the tilt test. The changes induced by the drugs on supine myocardial contractility are minor and not related with the outcome of the head-up tilt test.

Adrenergic beta-Antagonists↗
PubMed2000

A pilot experience with permanent biventricular pacing to treat advanced heart failure.

BACKGROUND: The prognosis and quality of life of patients with advanced heart failure remain poor. The purpose of this study was to evaluate new nonpharmacologic approaches. Biventricular pacing was proposed in this indication, based on the encouraging results of acute hemodynamics studies. METHODS: Fifty patients with drug-resistant heart failure (New York Heart Association [NYHA] class III/IV, 16 of 34) were consecutively implanted with biventricular pacemakers. All patients had severe dilated cardiomyopathy and intraventricular conduction delay. Survival, NYHA class, electrocardiogram, echocardiographic data, and exercise tolerance were assessed over a mean follow-up period of 15.4 +/- 10. 2 months. RESULTS: At the end of follow-up, 55% of patients were alive without heart transplantation or left ventricular assistance device. The mortality rate was significantly lower in class III (12. 5%) than in class IV patients (52.5%). In survivors, biventricular pacing significantly improved symptoms (NYHA class 2.2 +/- 0.5 at follow-up vs 3.7 +/- 0.5 at baseline) and exercise tolerance ((. )VO(2) peak 15.5 +/- 3.4 mL/min per kilogram at follow-up vs 11.1 +/- 3 mL/min per kilogram at baseline). CONCLUSIONS: Biventricular pacing appears to improve the functional status of patients with dilated cardiomyopathy with advanced heart failure. The technique appears to be attractive as an additive treatment, especially in class III patients. Controlled randomized studies are needed to validate this novel concept.

Aged↗
PubMed2000

Atrial overdriving is beneficial in patients with atrial arrhythmias: first results of the PROVE Study.

The AF Prevention by Overdriving (PROVE) trial is an ongoing prospective study of the effectiveness of atrial overdrive pacing combined with an Automatic Rest Rate function in the prevention of atrial arrhythmias. All patients who have received a Talent DR 213 pacemaker are eligible for enrollment into the study. After a 1-month monitoring period, the patients are divided into two groups. Group I includes patients with > or = 2 appropriate mode-switch (MS) episodes, or 1 MS episode of > or = 10 minutes, and/or > 300 atrial runs of > 5 beats/month. Group II includes all other patients. The number and duration of atrial arrhythmias are measured the pacemaker's Automatic Interpretation and Data Analysis software (AIDA). Patients' quality-of-life is measured by a validated functional status questionnaire. After having been grouped, the patients are randomly assigned, in a crossover design, to standard DDDR or overdrive pacing + Rest Rate, each programmed for a 3-month period. Preliminary results in 78 patients show a 34% reduction in the mean number of MS, and a mean 48% shortening of the overall duration of the episodes by overdrive pacing + Rest Rate, achieved by a mean 84% prevalence of atrial pacing. Overdrive pacing + Rest Rate was well tolerated and associated with a slight improvement in quality-of-life.

Aged↗
PubMed1999

Transcription factor activities and gene expression during mouse mammary gland involution.

Maintenance of mammary epithelial differentiation and milk production during lactation is a consequence of milk removal and the presence of lactogenic hormones, particularly glucocorticoids, insulin and prolactin. After weaning the fall in lactogenic hormones and milk stasis lead to involution, a process that is mainly characterized by three events: (i) downregulation of milk protein gene expression, (ii) loss of epithelial cells by apoptosis and, (iii) tissue remodeling and preparation of the gland for a new pregnancy. Each of these processes is likely to depend on the activity of specific sets of transcription factors in the mammary epithelium and stroma that ensure the timely and spatially coordinated expression of critical gene products such as mediators of apoptosis (e.g., caspase-1 and regulators of tissue remodeling events (e.g., matrix metalloproteinases). Here we describe signal transduction events such as activation of protein kinase A and JNK and changes in the activity of several transcription factors including Stat5, Stat3, NF1, Oct-1, and AP-1 during the early and late phases of mammary gland involution. We discuss their possible role in regulating and coordinating involution with emphasis on the apoptotic process of involution.

Animals↗
PubMed1999

Determination of the optimal atrioventricular delay in DDD pacing. Comparison between echo and peak endocardial acceleration measurements.

The goal of this study was to compare two methods determining the optimal atrioventicular delay (AVD) in 19 patients implanted with the BEST-Living system for complete heart block. The definition of the optimal AVD was: the AVD with the echo method that provided the longest diastolic filling time without interruption of the A wave, and the AVD with the peak endocardial acceleration (PEA) method, corresponding to the knee of the PEA curve vs AV delay. The amplitude of the PEA was measured for every AVD programmed via an automatic scanner in steps of 60 to 300 ms (40 ms steps): in the VDD pacing mode with a low base rate, to obtain 100% sensed P waves; in DDD with a base rate = sinus rate + 20%, to obtain 100% paced P waves. Echocardiographic (Echo) measurement of the left ventricular filling time were performed in the same AV delay settings in VDD and DDD as the ones tested in the PEA method, which were manually programmed. The optimal AVDs obtained in DDD and those obtained in VDD were compared in the echo and the PEA tests by a paired Student's t-test. The optimal AVDs obtained by both Echo and by PEA were also compared by a paired Student's t-test in VDD and DDD. The r value of the correlation between the optimal AVDs obtained by Echo and those obtained by PEA was calculated. Similar values of optimal AVD were obtained with both methods. The optimal AVDs given by the Echo technique (179 +/- 25 ms in DDD and 124 +/- 18 ms in VDD) were slightly, but significantly shorter than the ones obtained with the PEA method (202 +/- 21 ms in DDD and 145 +/- 18 ms in VDD, P < 0.05). A highly significant difference between AVD VDD and AVD DDD was found with both methods (P < 0.001). The correlation between the AVDs obtained with the echo and the PEA methods was highly significant (r = 0.78, P < 0.01). Pacemaker software could be modified to determine automatically the optimal AVDs to be applied throughout the heart rate range.

Atrioventricular Node↗
PubMed1999

Evidence suggesting that a chronic disease self-management program can improve health status while reducing hospitalization: a randomized trial.

OBJECTIVES: This study evaluated the effectiveness (changes in health behaviors, health status, and health service utilization) of a self-management program for chronic disease designed for use with a heterogeneous group of chronic disease patients. It also explored the differential effectiveness of the intervention for subjects with specific diseases and comorbidities. METHODS: The study was a six-month randomized, controlled trial at community-based sites comparing treatment subjects with wait-list control subjects. Participants were 952 patients 40 years of age or older with a physician-confirmed diagnosis of heart disease, lung disease, stroke, or arthritis. Health behaviors, health status, and health service utilization, as determined by mailed, self-administered questionnaires, were measured. RESULTS: Treatment subjects, when compared with control subjects, demonstrated improvements at 6 months in weekly minutes of exercise, frequency of cognitive symptom management, communication with physicians, self-reported health, health distress, fatigue, disability, and social/role activities limitations. They also had fewer hospitalizations and days in the hospital. No differences were found in pain/physical discomfort, shortness of breath, or psychological well-being. CONCLUSIONS: An intervention designed specifically to meet the needs of a heterogeneous group of chronic disease patients, including those with comorbid conditions, was feasible and beneficial beyond usual care in terms of improved health behaviors and health status. It also resulted in fewer hospitalizations and days of hospitalization.

Adult↗