Neuromuscular performance of paretic versus non-paretic plantar flexors after stroke.

The objective of this study was to compare the neuromuscular function of the paretic and non-paretic plantar flexors (i.e. soleus, gastrocnemius medialis, lateralis) in chronic stroke patients. It was hypothesized that the contractile rate of force development (RFD) and neural activation, assessed by electromyogram (EMG) and V-waves normalized to the M-wave, and voluntary activation (twitch interpolation) would be reduced during plantar flexor maximum voluntary isometric contraction and that the evoked muscle twitch properties would be reduced in the paretic limb. Ten chronic stroke survivors completed the study. The main findings were that the paretic side showed deteriorated function compared to the non-paretic leg in terms of (1) RFD in all analyzed time windows from force onset to 250 ms, although relative RFD (i.e. normalized to maximum voluntary force) was similar; (2) fast neural activation (for most analyzed time windows), assessed by EMG activity in time windows from EMG onset to 250 ms; (3) V-wave responses (except for gastrocnemius medialis); (4) voluntary activation; (5) the evoked peak twitch force, although there was no evidence of intrinsic muscle slowing; (6) EMG activity obtained at maximal voluntary force. In conclusion, this study demonstrates considerable neuromuscular asymmetry of the plantar flexors in chronic stroke survivors. Effective rehabilitation regimes should be investigated

Secretoneurin Is an Endogenous Calcium/Calmodulin-Dependent Protein Kinase II Inhibitor That Attenuates Ca2+-Dependent Arrhythmia

BACKGROUND: Circulating SN (secretoneurin) concentrations are increased in patients with myocardial dysfunction and predict poor outcome. Because SN inhibits CaMKII delta (Ca2+/calmodulin-dependent protein kinase II delta) activity, we hypothesized that upregulation of SN in patients protects against cardiomyocyte mechanisms of arrhythmia. METHODS: Circulating levels of SN and other biomarkers were assessed in patients with catecholaminergic polymorphic ventricular tachycardia (CPVT; n=8) and in resuscitated patients after ventricular arrhythmia-induced cardiac arrest (n=155). In vivo effects of SN were investigated in CPVT mice (RyR2 [ryanodine receptor 2]-R2474S) using adeno-associated virus-9-induced overexpression. Interactions between SN and CaMKII delta were mapped using pull-down experiments, mutagenesis, ELISA, and structural homology modeling. Ex vivo actions were tested in Langendorff hearts and effects on Ca2+ homeostasis examined by fluorescence (fluo-4) and patchclamp recordings in isolated cardiomyocytes. RESULTS: SN levels were elevated in patients with CPVT and following ventricular arrhythmia-induced cardiac arrest. In contrast to NT-proBNP (N-terminal proB- type natriuretic peptide) and hs-TnT (high-sensitivity troponin T), circulating SN levels declined after resuscitation, as the risk of a new arrhythmia waned. Myocardial pro-SN expression was also increased in CPVT mice, and further adeno-associated virus-9-induced overexpression of SN attenuated arrhythmic induction during stress testing with isoproterenol. Mechanistic studies mapped SN binding to the substrate binding site in the catalytic region of CaMKII delta. Accordingly, SN attenuated isoproterenol induced autophosphorylation of Thr287-CaMKII delta in Langendorff hearts and inhibited CaMKII delta-dependent RyR phosphorylation. In line with CaMKII delta and RyR inhibition, SN treatment decreased Ca2+ spark frequency and dimensions in cardiomyocytes during isoproterenol challenge, and reduced the incidence of Ca2+ waves, delayed afterdepolarizations, and spontaneous action potentials. SN treatment also lowered the incidence of early afterdepolarizations during isoproterenol; an effect paralleled by reduced magnitude of L-type Ca2+ current. CONCLUSIONS: SN production is upregulated in conditions with cardiomyocyte Ca2+ dysregulation and offers compensatory protection against cardiomyocyte mechanisms of arrhythmia, which may underlie its putative use as a biomarker in at-risk patients.Peer reviewe

Remote magnetic versus manual catheters: evaluation of ablation effect in atrial fibrillation by myocardial marker levels

Background A remote magnetic navigation (MN) system is available for radiofrequency ablation of atrial fibrillation (AF), challenging the conventional manual ablation technique. The myocardial markers were measured to compare the effects of the two types of MN catheters with those of a manual-irrigated catheter in AF ablation. Methods AF patients underwent an ablation procedure using either a conventional manual-irrigated catheter (CIR, n=65) or an MN system utilizing either an irrigated (RMI, n=23) or non-irrigated catheter (RMN, n=26). Levels of troponin T (TnT) and the cardiac isoform of creatin kinase (CKMB) were measured before and after ablation. Results Mean procedure times and total ablation times were longer employing the remote magnetic system. In all groups, there were pronounced increases in markers of myocardial injury after ablation, demonstrating a significant correlation between total ablation time and post-ablation levels of TnT and CKMB (CIR r=0.61 and 0.53, p<0.001; RMI r=0.74 and 0.73, p<0.001; and RMN r=0.51 and 0.59, p<0.01). Time-corrected release of TnT was significantly higher in the CIR group than in the other groups. Of the patients, 59.6% were free from AF at follow-up (12.2± 5.4 months) and there were no differences in success rate between the three groups. Conclusions Remote magnetic catheters may create more discrete and predictable ablation lesions measured by myocardial enzymes and may require longer total ablation time to reach the procedural endpoints. Remote magnetic non-irrigated catheters do not appear to be inferior to magnetic irrigated catheters in terms of myocardial enzyme release and clinical outcome

Long-term follow-up after surgery for atrial fibrillation with concomitant open heart surgery

BAKGRUNN Pasienter med atrieflimmer/flutter som skal gjennomgå en åpen hjerteoperasjon, kan behandles med ablasjon av arytmogene foci under samme inngrep. Sinusrytmen gjenopprettes hos de fleste på kort sikt, men langtidsresultatene er mer usikre. I denne studien, som er en del av den internasjonale CURE-AF-studien, evalueres resultater etter Cox-maze IV-operasjon for atrieflimmer i Norge ved oppfølging etter seks år. MATERIALE OG METODE 19 pasienter inngikk i denne prospektive kohortstudien. Atrieflimmer hadde vart i 40 måneder i gruppen med langvarig persisterende atrieflimmer (n = 12) og 6 måneder i gruppen med persisterende atrieflimmer (n = 7). Operasjon for atrieflimmer ble utført etter Cox-maze IV-prosedyren i CURE-AF-protokollen. De første 12 månedene var oppfølgingen strikt etter CURE-AF-protokoll, deretter var oppfølgingen i primærhelsetjenesten. RESULTATER Sinusrytme var reetablert hos 11 pasienter ved utskrivning og hos 14 pasienter seks måneder postoperativt. Ved oppfølging etter 5–6 år hadde alle pasienter med langvarig persisterende atrieflimmer fått residiv. To av disse fikk sinusrytme etter elektrokonvertering. Seks av syv i gruppen med persisterende atrieflimmer hadde sinusrytme etter 5–6 år. FORTOLKNING Initialt var resultatene gode, med retablering av sinusrytme hos over ⅔ av pasientene etter 6–9 måneder. Fem år senere ble det påvist høy residivfrekvens hos pasienter med langvarig persisterende atrieflimmer. Flere residiv var ikke blitt oppdaget eller forsøkt behandlet av helsevesenet

Long-term follow-up after surgery for atrial fibrillation with concomitant open heart surgery

BACKGROUND Patients with atrial fibrillation and atrial flutter scheduled to undergo open heart surgery can receive ablation treatment of arrhythmogenic foci during the same intervention. Sinus rhythm is restored in the majority in the short term, but the long-term results are more uncertain. This study, which is part of the international CURE-AF trial, evaluates results after Cox-Maze IV surgery for atrial fibrillation in Norway at six-year follow-up. MATERIAL AND METHOD Nineteen patients were included in this prospective cohort study. Atrial fibrillation had persisted for 40 months in the group with long-standing persistent atrial fibrillation (n = 12) and 6 months in the group with persistent atrial fibrillation (n = 7). Surgery for atrial fibrillation was performed according to the Cox-Maze IV procedure in the CURE-AF protocol. Follow-up in the first 12 months was strictly according to the CURE-AF protocol, thereafter conducted by the primary health service. RESULTS Sinus rhythm was restored in 11 patients at the time of discharge and in 14 patients six months postoperatively. After 5–6 years of follow-up, all patients with long-standing persistent atrial fibrillation had experienced recurrence. Two achieved sinus rhythm after electroconversion. Six of the seven in the group with persistent atrial fibrillation had sinus rhythm after 5–6 years. INTERPRETATION The results were good initially, with restoration of sinus rhythm in more than two thirds of the patients after 6–9 months. Five years later, a high recurrence rate was found in patients with long-standing persistent atrial fibrillation. Several recurrences had not been detected by the public health service or treatment had not been attempted

N-terminal pro-B-type natriuretic peptide level at longterm follow-up after atrial fibrillation ablation: A marker of reverse atrial remodeling and successful ablation

Aims: We investigated the relationship between arrhythmia burden, left atrial volume (LAV) and N-terminal pro-B-type natriuretic peptide (NT-pro-BNP) at baseline and after long-term follow-up of atrial fibrillation (AF) ablation. Methods: We studied 38 patients (23 paroxysmal, six women, mean age 56±11) scheduled for AF ablation. LAV was calculated on the basis of computed tomography images at baseline and long-term follow-up, and arrhythmia burden was graded from self-reported frequency and duration of AF episodes. Results: After a mean period of 22±5 months, 28/38 patients (11/15 persistent) were free from AF recurrence. At baseline there were no differences in mean LAV (125 vs. 130 cm3, p=0.7) or median NT-pro-BNP (33.5 vs. 29.5 pmol/L, p=0.9) between patients whose ablation had been successful or otherwise. At long-term follow-up there was a marked decrease in LAV (105 vs. 134 cm3, p 25% of baseline value had a specificity of 0.89 and a sensitivity of 0.6 (receiver operator characteristics, accuracy 0.82) for ablation success. Conclusions: NT-pro-BNP correlates with LAV and arrhythmia burden in AF patients and both NT-pro-BNP and LAV decrease significantly after successful ablation. A decrease in NT-pro-BNP of >25% from the baseline value could be useful as a marker of ablation success

10-year follow-up after radiofrequency ablation of idiopathic ventricular arrhythmias from right ventricular outflow tract

AbstractBackgroundThe aim of this study was to examine the effect of radiofrequency ablation (RFA) of ventricular arrhythmias from right ventricular outflow tract (RVOT) during long-term follow-up.MethodsA follow-up analysis was conducted using an in-house questionnaire, as well as a qualitative assessment of the patients' medical records. The study population of 34 patients had a previous diagnosis of idiopathic VT or frequent PVCs from the RVOT, and received RFA treatment between 2002 and 2005.ResultsThe main symptoms prior to RFA were palpitations (82.4%) and dizziness (76.5%). A reduction in symptoms following RFA was reported by 91.2% of patients (p < 0.001). Furthermore, there was a reduced use of antiarrhythmic medication after RFA (p < 0.001). General health perception classified on a scale of 1 (poor) to 4 (excellent), improved from median class 1 to 3 (p < 0.001) during long-term follow-up. The fitness to work increased from median class 3 to class 5 (1 = incapacitated, 5 = full time employment, p = 0.038), while the rate of patients in full time employment increased from 26.5% to 55.9% after RFA (p = 0.02).ConclusionsA reduction of symptoms and use of antiarrhythmic medication, as well as an improvement in the general health perception and fitness to work after RFA of idiopathic ventricular arrhythmias can be demonstrated at ten-year follow-up