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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cardiac function and electrical stability may be improved by programming of optimal AV delay in DDD pacing. This study tested the hypothesis if the global atrial conduction time at various pacing sites can be derived from the surface ECG to achieve an optimal electromechanical timing of the left heart. Data were obtained from 60 patients following dual chamber pacemaker implantation. Right atrial septal pacing was associated with significantly shorter atrial conduction time (P < 0.0005) and P wave duration (P < 0.005), compared to standard right atrial pacing sites at the right atrial appendage or at the right free wall. The last two pacing sites showed no significant difference. In a group of 31 patients with AV block, optimal AV delay was achieved by programming a delay of 100 ms from the end of the paced P wave to peak/nadir of the paced ventricular complex. Optimization of AV delay resulted in a relative increase of echocardiographic stroke volume (SV) (10.9 +/- 13.7%; 95% CI: 5.9-15.9%) when compared to nominal AV delay (170 ms). Optimized AV delay was highly variable (range 130-250 ms; mean 180 +/- 35 ms). The hemodynamic response was characterized by a weak significant relationship between SV increase and optimized AV delay (R2 = 0.196, R = 0.443, P = 0.047). The study validated that septal pacing is advantageous for atrial synchronization compared to conventional right atrial pacing. Tailoring the AV delay with respect to the surface ECG improved systolic function significantly and was superior to nominal AV delay settings in the majority of patients.
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PMID:Evaluation of atrial conduction time at various sites of right atrial pacing and influence on atrioventricular delay optimization by surface electrocardiography. 1507 99

A 79-year-old man presented with dilated cardiomyopathy and chronic atrial fibrillation. A DDD pacemaker was implanted due to sick sinus syndrome. His left ventricular ejection fraction was 23%. He was repeatedly admitted with congestive heart failure. Although cardiac resynchronization therapy was attempted, insertion of a pacing lead into the coronary sinus failed. Right ventricular bifocal pacing was done. The QRS width was shortened to 155 msec during bifocal pacing and 157 msec during right ventricular outflow pacing from 221 msec during right ventricular apical pacing. Heart failure was improved from New York Heart Association class III to II. Regional wall motion was assessed by strain of the myocardium. Bifocal pacing increased stroke volume due to improvement of longitudinal dyssynchrony of the septal and lateral walls. Bifocal pacing is effective for patients with severe congestive heart failure in whom biventricular pacing therapy has failed. Strain Doppler imaging is useful for the assessment of regional wall motion during cardiac pacing.
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PMID:[Assessment of regional wall motion using strain Doppler imaging during right ventricular bifocal pacing in a patient with severe congestive heart failure: a case report]. 1537 39

The Canadian trial of physiologic pacing (CTOPP), published in 2000, demonstrated a reduction in atrial fibrillation (AF), stroke and death with preservation of atrioventricular synchrony, though only the lower rate of AF was statistically significant. The purpose of this study was to determine the effect of CTOPP on pacing mode selection in our region. The British Columbia Cardiac Registry contains prospectively entered data covering a population of 4 millions (M) and 17 implanting centers. It was examined for mode selection trends from 1997 to 2002. At examination, there were data on 22,446 pulse generators (PG) and 29,898 leads. New implant rates per M population were 1997:473; 1998:456; 1999:505; 2000:513; 2001:486; 2002:510. PG replacements also increased, resulting in a total implant rate of 667 PG per M in 2002. Over the 6-year period, DDD use decreased from 321 to 306, but DDDR use, more than doubled from 317 to 750 PG/year. VVI use steadily decreased from 741 to 410 PG/year, while VVIR use increased more modestly from 1997 to 1999, then remained stable. During the 6-year period bracketing CTOPP, use of modes maintaining AV synchrony increased by over 32%, to 53% of PG implanted in 2002. Our PG implant rate was much higher than expected from prior retrospective surveys, and similar to rates in Belgium, France, and Germany. CTOPP did not decrease our use of physiologic pacing but, instead, was associated with a brief pause, then progressively increased in both academic and community centers. Patients' need and widely accepted standards of care proved more important in clinical decision making than the results of a flawed randomized trial.
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PMID:Use of physiologic pacing after the Canadian trial of physiologic pacing. 1568 29

Evidence from randomized trials indicates that the clinical benefits of dual-chamber (DDD) pacing are modest: (i) no significant differences exist between physiological pacing and single-chamber pacing in mortality and stroke; (ii) ventricular desynchronization resulting from chronic right-ventricular pacing in DDD mode, induces a significantly increased incidence of atrial fibrillation (AF) and heart failure hospitalizations; (iii) AF pacing prevention and therapy algorithms have shown a modest to minimal or absent efficacy; (iv) the widespread use of physiological pacemakers is not an economically attractive strategy. Thus, these data provide a reliable body of evidence on which to make more rationale clinical decisions for individual patients and policy decisions for health costs saving. The cheaper single-chamber AAI(R) or VVI(R) has been shown to satisfy both conditions in most cases of sinus node disease and AV block.
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PMID:Pacemaker selection: time for a rethinking of complex pacing systems? 1620 37

Permanent cardiac pacing is a widely recognized therapy used for the treatment of several types of bradycardia, atrioventricular (AV) block and sinoatrial node disease mainly. In the beginning, implantable cardiac pacemakers stimulated just one cardiac chamber and right ventricule pacing were the most frequently used devices. In the 1980s, pacemaker's technology focus on restoring AV synchrony, named <<physiologic>> cardiac pacing, allowing the development of dual-chamber pacemakers (DDD, DDDR). Even though theoretical advantages of dual-chamber devices, its implantation is more complicated and expensive. For these reasons, the selection of the optimum mode of pacing is still controversial. Nowadays, available results from many trials that analyze clinical and physiological benefits of the different pacing modes, allow us to conclude that physiologic pacemakers reduce the risk of atrial fibrillation but do not improve survival and do not reduce the risk of stroke. By other hand, the reduction of pacemaker syndrome is not a constant finding in all the trials. In our clinical practice, when we have to select the pacing mode we have to take in account these results together with other factors as patient's characteristics (age, comorbility and life expectansy). Also, data from cost-effectiveness analysis should be added to the available information for the making decision.
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PMID:[Selection of pacemaker stimulation mode]. 1693 95

Previous electroencephalographic and magnetoencephalographic (MEG) studies demonstrate that the activity in the delta band can increase not only in the perilesional area, but also in the contralesional hemisphere in patients affected by a monolateral stroke. The increase of delta activity in the unaffected hemisphere (UH) in the acute phase after an unilateral stroke seems to add prognostic information about clinical recovery. Delta activity in perirolandic regions was investigated via MEG in a group of 27 patients affected by stroke in the territory of middle cerebral artery in the first week following the symptom onset. Clinical evaluation was performed in the acute and the post-acute (median 9 months) phase. Delta band power, delta dipole density (DDD, the number of accepted single dipole fits per second in parieto-frontal region) and delta dipole strength (DDS, the average of the accepted dipoles strengths) were evaluated in both hemispheres, separated on the basis of the lesion level (cortical and subcortical involvement) and correlated with lesion volume, clinical status in acute phase and recovery level. Although in our patient cohort DDD did not differ in both hemispheres with respect to control values, DDS showed higher level than in controls both in affected hemisphere (AH) and UH, was dependent on the lesion level and positively correlated with the lesion volume. Moreover, while AH and UH DDSs were not associated with clinical status in acute phase, they correlated with clinical recovery in post-acute phase. These properties confirmed findings obtained by spectral power analysis and provided a localized delta activity amplitude estimate, independent of measuring system and allowing inter-laboratory standardization.
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PMID:Delta dipole density and strength in acute monohemispheric stroke. 1732 84

This research is aimed to the determination of the changes in the cardiac energetic output for three different modes of cardiac rhythm pacing. The clinical investigation of thirteen patients with the permanent dual-chamber pacemaker implantation was carried out. The patients were taken to echocardiography examination conducted by way of three pacing modes (AAI, VVI and DDD). The myocardial energetic parameters-the stroke work index (SWI) and the myocardial oxygen consumption (MVO2) are not directly measurable, however, their values can be determined using the numerical model of the human cardiovascular system. The 24-segment hemodynamical model (pulsating type) of the human cardiovascular system was used for the numerical simulation of the changes of myocardial workload for cardiac rhythm pacing. The model was fitted by well-measurable parameters for each patient. The calculated parameters were compared using the two-tailed Student's test. The differences of SWI and MVO2 between the modes AAI and VVI and the modes DDD and VVI are statistically significant (P<0.05). On the other hand, the hemodynamic effects for the stimulation modes DDD and AAI are almost identical, i.e. the differences are statistically insignificant (P>0.05).
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PMID:Determination of myocardial energetic output for cardiac rhythm pacing. 1808 Feb 8

A 72-year-old man implanted with a biventricular pacemaker was diagnosed pyonephrosis, and left nephrectomy was performed under general and epidural anesthesia. Urologists were going to use a monopolar electrocautery during the operation. Before the operation, we attempted to convert the pacemaker from DDD mode to DOO mode with a precordial magnet because we wanted to know the effect of DOO mode in this patient implanted with a biventricular pacemaker and how a monopolar electrocautery interfered the biventricular pacemaker. His blood pressure and heart rate were stable during DOO mode by a precordial magnet, but the stroke volume was reduced a little. Then, we suggested surgeons the minimal use of the monopolar electrocautery. Actually, intraoperative use of the monopolar electrocautery did not interfere his pacemaker, and the operation was completed uneventfully. Recently in Japan, cardiac resynchronization therapy (CRT) becomes more common and operations in the patients implanted with biventricular pacemakers will become more frequent. The surgeons and anesthesiologists should take in mind that the monopolar electrocautery is appropriate or not depending on the individual patient.
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PMID:[Anesthetic management for nephrectomy using a monopolar electrocautery in a patient implanted with a biventricular pacemaker]. 1917 23

This study was designed to evaluate the left ventricular systolic synchronization in patients implanted with dual-chamber DDD mode cardiac pacemakers by real-time three-dimensional echocardiography (RT3DE). Twenty patients implanted with DDD mode cardiac pacemakers for 12 months and 20 healthy subjects underwent RT3DE. This method provided left ventricular end-diastolic volume (LEDV), left ventricular end-systolic volume (LESV), stroke volume (SV), left ventricular ejection fraction (LVEF), the mean value of the time to minimal systolic volume of the 16 left ventricular segments (Tmean), the standard deviation of Tmean (T-SD), the maximal difference of the time to minimal systolic volume of the 16 left ventricular segments (Tmax) and time-volume curves of the 16 left ventricular segments. Results showed that compared with the healthy group, LESV was significantly increased (P<0.05), SV and LVEF were significantly decreased (P<0.05) and T-SD and Tmax were significantly prolonged (P<0.05) in patients implanted with DDD mode cardiac pacemakers. The time to minimal systolic volume of the 16 left ventricular segments time-volume curves differed in patients implanted with DDD mode cardiac pacemakers. Asynchronization of the left ventricular systolic performance in patients implanted with DDD mode cardiac pacemakers was observed. The results showed that RT3DE is a quantitative method used to evaluate left ventricular systolic synchronization.
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PMID:Use of real-time three-dimensional echocardiography to assess left ventricular systolic synchronization after dual-chamber pacing therapy. 2322 51

Sinus node disease (SND), a common indication to implant a pacemaker, is frequently associated with atrial fibrillation (AF), either at implantation (paroxysmal AF) or during follow-up, which often evolves to persistent or permanent AF. Pacemakers with an atrial lead allow continuous monitoring of the atrial rhythm and enable detection of the burden of AF. Asymptomatic atrial tachyarrhythmias, being associated with increased risk of stroke, have important prognostic implications, and their detection could guide decision-making about antithrombotic prophylaxis. Pacing mode and pacing algorithms can influence the occurrence of AF and atrial tachyarrhythmias. In DDD/DDDR pacing mode, reduction of unnecessary right ventricular pacing positively affects the occurrence and evolution of AF, but patients with a history of atrial tachyarrhythmias maintain an increased risk of arrhythmic events. In the MINERVA study, the use of algorithms that act in the atrium for preventive pacing and atrial antitachycardia pacing while minimizing right ventricular pacing was beneficial in patients with SND and previous atrial tachyarrhythmias, and was associated with a significant reduction in evolution to permanent AF. New information available on therapies delivered at the atrial level by implanted devices suggests clinical advantages that could improve current guidelines for the management of AF and atrial tachyarrhythmias.
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PMID:Management of atrial fibrillation in bradyarrhythmias. 2578 13


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