Browsing by Subject "ARRHYTHMIAS"

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  • Koponen, Mikael; Havulinna, Aki S.; Marjamaa, Annukka; Tuiskula, Annukka M.; Salomaa, Veikko; Laitinen-Forsblom, Päivi J.; Piippo, Kirsi; Toivonen, Lauri; Kontula, Kimmo; Viitasalo, Matti; Swan, Heikki (2018)
    Background: Long QT syndrome (LQTS) is an inherited cardiac disorder predisposing to sudden cardiac death (SCD). We studied factors affecting the clinical course of genetically confirmed patients, in particular those not receiving beta-blocker treatment. In addition, an attempt was made to associate risk of events to specific types of KCNQ1 and KCNH2 mutations. Methods: A follow-up study covering a mean of 18.6 +/- 6.1 years was conducted in 867 genetically confirmed LQT1 and LQT2 patients and 654 non-carrier relatives aged 18-40 years. Cox regression models were used to evaluate the contribution of clinical and genetic risk factors to cardiac events. Results: In mutation carriers, risk factors for cardiac events before initiation of beta-blocker included LQT2 genotype (hazard ratio [HR] = 2.1, p = 0.002), female gender (HR = 3.2, p <0.001), a cardiac event before the age of 18 years (HR = 5.9, p <0.001), and QTc >= 500 ms (vs <470 ms, HR = 2.7, p = 0.001). LQT1 patients carrying the KCNQ1 D317N mutation were at higher risk (HR = 3.0-3.9, p <0.001-0.03) compared to G589D, c. 1129-2A > G and other KCNQ1 mutation carriers after adjusting for gender, QTc duration, and cardiac events before age 18. KCNH2 c. 453delC, L552S and R176W mutations associated with lower risk (HR = 0.11-0.23, p <0.001) than other KCNH2 mutations. Conclusions: LQT2 (compared to LQT1), female gender, a cardiac event before age 18, and long QT interval increased the risk of cardiac events in LQTS patients aged 18 to 40 years. The nature of the underlying mutation may be associated with risk variation in both LQT1 and LQT2. The identification of high-risk and low-risk mutations may enhance risk stratification.
  • Lahtinen, Annukka M.; Noseworthy, Peter A.; Havulinna, Aki S.; Jula, Antti; Karhunen, Pekka J.; Kettunen, Johannes; Perola, Markus; Kontula, Kimmo; Newton-Cheh, Christopher; Salomaa, Veikko (2012)
  • Kuusela, Jukka; Kujala, Ville J.; Kiviaho, Anna; Ojala, Marisa; Swan, Heikki; Kontula, Kimmo; Aalto-Setala, Katriina (2016)
    Human induced pluripotent stem cells (hiPSC) have enabled a major step forward in pathophysiologic studies of inherited diseases and may also prove to be valuable in in vitro drug testing. Long QT syndrome (LQTS), characterized by prolonged cardiac repolarization and risk of sudden death, may be inherited or result from adverse drug effects. Using a microelectrode array platform, we investigated the effects of six different drugs on the electrophysiological characteristics of human embryonic stem cell-derived cardiomyocytes as well as hiPSC-derived cardiomyocytes from control subjects and from patients with type 1 (LQT1) and type 2 (LQT2) of LQTS. At baseline the repolarization time was significantly longer in LQTS cells compared to controls. Isoprenaline increased the beating rate of all cell lines by 10-73 % but did not show any arrhythmic effects in any cell type. Different QT-interval prolonging drugs caused prolongation of cardiac repolarization by 3-13 % (cisapride), 10-20 % (erythromycin), 8-23 % (sotalol), 16-42 % (quinidine) and 12-27 % (E-4031), but we did not find any systematic differences in sensitivity between the control, LQT1 and LQT2 cell lines. Sotalol, quinidine and E-4031 also caused arrhythmic beats and beating arrests in some cases. In summary, the drug effects on these patient-specific cardiomyocytes appear to recapitulate clinical observations and provide further evidence that these cells can be applied for in vitro drug testing to probe their vulnerability to arrhythmia.
  • Koponen, Mikael; Marjamaa, Annukka; Tuiskula, Annukka M.; Viitasalo, Matti; Nallinmaa-Luoto, Terhi; Leinonen, Jaakko T.; Widen, Elisabeth; Toivonen, Lauri; Kontula, Kimmo; Swan, Heikki (2020)
    Background Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a severe inherited arrhythmic disease associated with a risk of syncope and sudden cardiac death (SCD). Aims We aimed at identifying RYR2 P2328S founder mutation carriers and describing the clinical course associated with the mutation. Methods The study population was drawn from the Finnish Inherited Cardiac Disorder Research Registry, and from the present genealogical study. Kaplan-Meier graphs, log-rank test and Cox regression model were used to evaluate the clinical course. Results Genealogical study revealed a common ancestor couple living in the late 17(th) century. A total of 1837 living descendants were tested for RYR2 P2328S mutation unveiling 62 mutation carriers aged mean 3923 years old. No arrhythmic deaths were documented among genotyped subjects, but 11 SCDs were detected in non-genotyped family members since 1970. Three genotyped patients (5%) suffered an aborted cardiac arrest (ACA), and 15 (25%) had a syncope triggered by exercise or stress. Rate of cardiac events was higher among patients who in exercise stress test showed a maximum rate of premature ventricular contractions >30/min (68% vs 17%, p-blocker medication. Conclusions Previously undiagnosed CPVT patients may be identified by well-conducted genealogical studies. The RYR2 P2328S mutation causes a potentially severe phenotype, but its expression is variable, thus calling for additional studies on modifying factors.
  • Salmi, Samuli J.; Nieminen, Tuomo; Hartikainen, Juha; Biancari, Fausto; Lehto, Joonas; Nissinen, Maunu; Malmberg, Markus; Yannopoulos, Fredrik; Savolainen, Jyri; Airaksinen, Juhani; Kiviniemi, Tuomas (2020)
    OBJECTIVES: We sought to study the indications, long-term occurrence, and predictors of permanent pacemaker implantation (PPI) after isolated surgical aortic valve replacement with bioprostheses. METHODS: The CAREAVR study included 704 patients (385 females, 54.7%) without a preoperative PPI (mean +/- standard deviation age 75 +/- 7years) undergoing isolated surgical aortic valve replacement at 4 Finnish hospitals between 2002 and 2014. Data were extracted from electronic patient records. RESULTS: The follow-up was median 4.7years (range 1day to 12.3years). Altogether 56 patients received PPI postoperatively, with the median 507days from the operation (range 6days to 10.0years). The PPI indications were atrioventricular block (31 patients, 55%) and sick sinus syndrome (21 patients, 37.5%). For 4 patients, the PPI indication remained unknown. A competing risks regression analysis (Fine-Gray method), adjusted with age, sex, diabetes, coronary artery disease, preoperative atrial fibrillation (AF), left ventricular ejection fraction, New York Heart Association class, AF at discharge and urgency of operation, was used to assess risk factors for PPI. Only AF at discharge (subdistribution hazard ratio 4.34, 95% confidence interval 2.34-8.03) was a predictor for a PPI. CONCLUSIONS: Though atrioventricular block is the major indication for PPI after surgical aortic valve replacement, >30% of PPIs are implanted due to sick sinus syndrome during both short-term follow-up and long-term follow-up. Postoperative AF versus sinus rhythm conveys >4-fold risk of PPI.
  • Naumenko, Nikolay; Huusko, Jenni; Tuomainen, Tomi; Koivumaki, Jussi T.; Merentie, Mari; Gurzeler, Erika; Alitalo, Kari; Kivela, Riikka; Yla-Herttuala, Seppo; Tavi, Pasi (2017)
    Vascular endothelial growth factor B (VEGF-B) is a potentmediator of vascular, metabolic, growth, and stress responses in the heart, but the effects on cardiac muscle and cardiomyocyte function are not known. The purpose of this study was to assess the effects of VEGF-B on the energy metabolism, contractile, and electrophysiological properties of mouse cardiac muscle and cardiac muscle cells. In vivo and ex vivo analysis of cardiac-specific VEGF-B TG mice indicated that the contractile function of the TG hearts was normal. Neither the oxidative metabolism of isolated TG cardiomyocytes nor their energy substrate preference showed any difference to WT cardiomyocytes. Similarly, myocyte Ca2+ signaling showed only minor changes compared to WT myocytes. However, VEGF-B overexpression induced a distinct electrophysiological phenotype characterized by ECG changes such as an increase in QRSp time and decreases in S and R amplitudes. At the level of isolated TG cardiomyocytes, these changes were accompanied with decreased action potential upstroke velocity and increased duration (APD60-70). These changes were partly caused by downregulation of sodium current (INa) due to reduced expression of Nav1.5. Furthermore, TG myocytes had alterations in voltage-gated K + currents, namely decreased density of transient outward current (Ito) and total K + current (Ipeak). At the level of transcription, these were accompanied by downregulation of Kv channel-interacting protein 2 (Kcnip2), a knownmodulatory subunit for Kv4.2/3 channel. Cardiac VEGF-B overexpression induces a distinct electrophysiological phenotype including remodeling of cardiomyocyte ion currents, which in turn induce changes in action potential waveform and ECG.