V České republice je indikace k profylaktické implantaci ICD u pacientů po infarktu myokardu založena na přítomnosti systolické dysfunkce LK, na nálezu NSVT a indukovatelnosti VT/VF při programované stimulaci komor. Nekonvenční holterovské ukazatele rizika u pacientů po IM mají silnější prediktivní charakteristiky než všechny doposud známé klinické a elektrofyziologické rizikové faktory. Cílem projektu je prospektivně ověřit, zda stratifikace rizika u poinfarktových pacientů, která využívá tyto nové holterovské prediktory, je efektivnější než současné klinické postupy. Do studie bude zařazeno 600 pacientů po dokumentovaném infarktu myokardu, s ejekční frakcí LK <= 35%. Bude sledován kombinovaný endpoint (kardiální úmrtí + nefatální srdeční zástava + první adekvátní ICD terapie).; Non-conventional Holter-based risk predictors - Heart Rate Turbulence (HRT) and Prevalent Low-Frequency Oscillation (PLF) - were established as powerful risk stratifiers in patients after myocardial infarction (MI). The aim of the project is to validateprospectively whether risk stratification of postinfarction patients with left ventricular (LV) dysfunction based on specific combination of PLF and HRT is more effective than current strategy in Czech Republic. The study will enroll 600 patients after documented MI, with LV dysfunction (LV ejection fraction <= 40%). PES will be performed in patients with NSVT and/or abnormal composite Holter-based risk predictor. ICD will be implanted in patients with inducible VT/VF during PES. During mean follow up of 24 months, the occurrence of combined endpoint (cardiac death + nonfatal cardiac arrest + appropriate ICD therapy) will be investigated.

• MeSH
• elektrokardiografie ambulantní MeSH
• infarkt myokardu MeSH
• mortalita MeSH
• srdeční arytmie MeSH
• srdeční elektrofyziologie MeSH
• systolické srdeční selhání MeSH
• zohlednění rizika MeSH

• Konspekt
• Patologie. Klinická medicína
• NLK Obory
• angiologie
• kardiologie
• NLK Publikační typ
• závěrečné zprávy o řešení grantu IGA MZ ČR

BACKGROUND: This study tested the hypothesis that heart rate turbulence (HRT) following ventricular pacing trains depends on train cycle length, presence of retrograde ventriculoatrial (VA) conduction, and left ventricular (LV) function. METHODS: We analyzed digital recordings of programmed ventricular stimulation (PVS) performed in 82 patients (57 men) referred for electrophysiologic studies of ventricular arrhythmias, whose mean age was 64 +/- 12 years and LV ejection fraction (EF) was 47 +/- 15%. Profiles of sinus RR intervals after all available 8-beat ventricular pacing trains (600-and 400-ms) were averaged. Heart rate turbulence slope (HRTS) was analyzed as the maximum positive slope of a regression line through a sequence of 2-5 (HRTS2 - HRTS5) consecutive RR intervals within the first 5 RR intervals after the pacing train. RESULTS: Dynamics of RR intervals had biphasic and monophasic patterns, in patients with and without VA conduction, respectively. Sinus nodal response was less prominent after 600-ms than 400-ms pacing trains. After 400-ms pacing trains, HRTS was significantly shallower in patients with LVEF 40%. HRTS4 was the best discriminator between the two groups (6.8 +/- 8.6 ms/RR vs 19.6 +/- 26.0 ms/RR, P = 0.017). CONCLUSION: In patients with VA conduction, HRT after ventricular pacing trains reflects a combination of vagal withdrawal due to transient hypotension and suppression of sinus node automaticity. Attenuation of vagal modulation was detected in patients with LV dysfunction during standard PVS.

• MeSH
• autonomní nervový systém patofyziologie   MeSH
• funkce levé komory srdeční MeSH
• kardiostimulace umělá * MeSH
• komorové extrasystoly * patofyziologie   terapie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• retrospektivní studie MeSH
• senioři MeSH
• srdeční arytmie MeSH
• srdeční frekvence * MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• práce podpořená grantem MeSH

BACKGROUND: Positive Turbulence onset (TO) after atrial premature complexes (APCs) was found temporally related to spontaneous episodes of atrial fibrillation. This study tested the hypothesis that heart rate turbulence (HRT) after APCs is influenced by APC prematurity independently of the prematurity of conducted ventricular complexes. METHODS: We studied 33 patients (mean age = 58 +/- 16 years, 19 men), 11 of whom had structural heart disease, who were referred for electrophysiological studies of supraventricular or ventricular arrhythmias. Sequences of single right atrial extrastimuli were delivered with coupling intervals adjusted to reach 60% prematurity of conducted ventricular complexes. Descriptors of HRT were compared between patients with slow versus fast atrioventricular (AV) conduction of APCs. RESULTS: The early RR interval dynamics after APCs was prominently modulated by the suppression of sinus node automaticity by the direct effect of APCs. This effect was significantly greater after earlier APCs with longer AV conduction times than after later coupled APCs with shorter AV conduction times. CONCLUSIONS: The early phase of HRT is strongly influenced by the coupling interval of APCs, independently of the prematurity of conducted ventricular complexes. Consequently, the more positive TO preceding spontaneous atrial fibrillation episodes might be an epiphenomenon of incidental short-coupled APCs with delayed AV conduction, likely to trigger atrial fibrillation.

• MeSH
• dospělí MeSH
• fibrilace síní * patofyziologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• nodus atrioventricularis patofyziologie   MeSH
• senioři MeSH
• síňové extrasystoly * patofyziologie   MeSH
• srdeční frekvence * MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• práce podpořená grantem MeSH
• srovnávací studie MeSH

BACKGROUND: Various indexes of 24-hour heart rate variability (HRV) have been able to predict all-cause mortality after an acute myocardial infarction (AMI), but their value in predicting specific modes of cardiac death has been limited. AIM: The aim of this study was to assess the role of two novel spectral indexes of HRV as predictors of either sudden (SCD) or non-sudden cardiac death after an AMI. Method. We used two novel methods of spectral analysis of HRV: 1) the high-frequency (HF) spectral component, V(index), calculated as an average HF power from the most linear portion of HF power versus the R-R interval regression curve, and 2) the prevalent low-frequency oscillation of heart rate (PLF). V(index), conventional HRV measures, and PLF were analyzed from 24-hour Holter recordings of 590 patients with a recent AMI. RESULTS: During the mean follow-up of 39+/-14 months, SCD occurred in 3% (n = 17) and non-sudden cardiac death in 5% (n = 28) of the patients. In univariate analysis, V(index) was the most potent predictor of SCD (RR: 6.0, 95% CI: 1.7-20.7, P<0.01), also remaining the most powerful predictor of SCD after adjustment for clinical variables and ejection fraction (RR: 4.2, 95% CI: 1.2-15.2, P<0.05). PLF was a potent predictor of non-sudden cardiac death (RR: 13.9, 95% CI: 5.9-32.5, P<0.001), but it did not predict SCD. CONCLUSIONS: Novel spectral HRV analysis methods, V(index) and PLF, provide significant information of the risk of the specific mode of death after an AMI.

• MeSH
• časové faktory MeSH
• cirkadiánní rytmus * fyziologie   MeSH
• echokardiografie MeSH
• elektrokardiografie MeSH
• infarkt myokardu * ošetřování   patofyziologie   ultrasonografie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• míra přežití MeSH
• náhlá srdeční smrt * epidemiologie   etiologie   MeSH
• následné studie MeSH
• prognóza MeSH
• retrospektivní studie MeSH
• srdeční frekvence * fyziologie   MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• klinické zkoušky MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Finsko MeSH

NTRODUCTION: Late heart rate deceleration parallels the increase of systolic blood pressure during heart rate turbulence (HRT) after ventricular premature complexes (VPC). This is consistent with the involvement of baroreflex mechanism. Physiological background of systolic blood pressure dynamics is not known. Enhanced sympathetic activation and nonautonomic post-VPC changes of stroke volume have been speculated on. METHODS AND RESULTS: We studied 28 subjects (aged 56 +/- 11 years; 20 males; 18 normal and 10 abnormal left ventricular (LV) function) with spontaneous occurrence of VPCs. HRT indices and baroreflex sensitivity were analyzed from the ECGs and finger arterial pressure recordings during 30 minutes of spontaneous respiration in supine position. Beat-by-beat stroke volume and peripheral vascular resistance were computed by a nonlinear, self-adaptive model of aortic input impedance (Modelflow, Finapres Medical Systems, Arnhem, The Netherlands). Indices of HRT and baroreflex sensitivity were highly correlated. In patients with preserved LV function, there was no substantial dynamics of stroke volume in the late phase after VPC, while peripheral vascular resistance increased significantly. In patients with impaired LV function, potentiated first sinus beat after VPC triggered transient hemodynamic alternans. Dynamics of peripheral vascular resistance was attenuated and stroke volume was depressed in the late phase after VPC. CONCLUSIONS: Delayed sympathetically mediated vasomotor response to VPC produces systolic blood pressure overshoot. This subsequently induces vagally mediated late heart rate deceleration. Under physiologic conditions, there is no evidence of other hemodynamic and/or mechanical effect outside the autonomic reflex arch. In patients with LV dysfunction, both depressed vagal and sympathetic modulation and, indirectly, enhanced postextrasystolic potentiation account for attenuated HRT.

• MeSH
• analýza rozptylu MeSH
• autonomní nervový systém patofyziologie   MeSH
• baroreflex fyziologie   MeSH
• cévní rezistence fyziologie   MeSH
• elektrokardiografie MeSH
• financování organizované MeSH
• komorové extrasystoly patofyziologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• regresní analýza MeSH
• srdeční frekvence fyziologie   MeSH
• tepový objem fyziologie   MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH

Prevalent low-frequency (PLF) oscillation of heart rate and turbulence slope (TS) are both powerful postmyocardial infarction (MI) risk factors. Abnormal composite risk stratifier (CRS) was defined as abnormal PLF or abnormal TS when PLF was not analyzable. We compared the predictive power of CRS with the previously published predictive value of conventional electrophysiological (EP) testing based on the presence of nonsustained ventricular tachycardia (NSVT) and inducibility of sustained ventricular tachycardia/fibrillation (VT/VF) during programmed ventricular stimulation (PVS). PLF and TS were calculated from baseline Holter recordings in the placebo population of European Amiodarone Infarction Myocardial Infarction Trial (EMIAT trial) (n = 633; LVEF /= 0.1 Hz and TS

• MeSH
• elektrofyziologie MeSH
• elektrokardiografie ambulantní * MeSH
• hodnocení rizik MeSH
• infarkt myokardu mortalita   patofyziologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• prediktivní hodnota testů MeSH
• srdeční frekvence * MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• práce podpořená grantem MeSH
• srovnávací studie MeSH

Atrial and ventricular premature beats (APB, VPB) cause consistent changes in the sinus-cycle length known as heart rate (HR) turbulence. HR turbulence is described by turbulence onset (TO) and turbulence slope (TS). This article investigated into whether specific QT interval changes are associated with HR turbulence and whether these can be assessed using HR turbulence quantifiers. A total of 40 patients (54 +/- 16 years, 34 men) referred for electrophysiological evaluation for ventricular tachycardia (VT) underwent a study protocol prior to programmed electrical stimulation. The protocol consisted of three consecutive series of atrial and ventricular stimulation with single extrastimuli delivered from the high right atrium and the right ventricular apex at a coupling interval decremented from 750 to 400 ms at a 50-ms step. A 20-second period of sinus rhythm was allowed between ES. Turbulence onset and TS after an APB and a VPB were calculated separately using a dedicated computer algorithm. Consistent changes in the QT interval (QT turbulence) were observed immediately after premature beats and were determined using TO. QT TO was calculated as a relative difference between the QT interval of the first sinus cycle after the induced premature beat and the mean of the QT intervals of the two sinus cycles preceding the premature beat. QT turbulence was present following both APBs and VPBs but was less pronounced after an APB. In contrast to negative VPB-induced TO of HR turbulence reflecting early acceleration of the HR, VPB-induced TO of QT turbulence was positive showing lengthening of the QT interval following a VPB. The subgroup analysis has shown that QT turbulence was significantly attenuated in patients with ischemic heart disease and a left ventricular (LV) ejection fraction (EF) 0.40 (after an APB: 0.73 +/- 0.31% vs 2.58 +/- 0.31%, respectively, P = 0.0044; after a VPB: 1.18 +/- 0.29% vs 4.40 +/- 1.38%, respectively, P = 0.0026). Neither APB nor VPB produced late QT dynamics equivalent to TS of HR turbulence. QT-interval turbulence occurs in association with HR turbulence following induced VPB and APB but QT dynamics is opposite to that of HR. It can be expressed as TO but not TS. Patients with ischemic VT and LV dysfunction exhibited significantly lower QT TO values than those with nonischemic VT and normal ventricular function.

• MeSH
• elektrofyziologie MeSH
• elektrokardiografie * MeSH
• hemodynamika MeSH
• komorová tachykardie * patofyziologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• srdeční frekvence * fyziologie   MeSH
• srdeční komory MeSH
• srdeční síně MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH

• MeSH
• biofyzika MeSH
• biofyzikální jevy MeSH
• lidé MeSH
• srdce - funkce síní * MeSH
• srdeční frekvence * fyziologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• dopisy MeSH
• komentáře MeSH