Familial risk for endometriosis and its interaction with smoking, age at menarche and body mass index: a population-based cohort study among siblings.

OBJECTIVE: To quantify familial risk of endometriosis among full siblings and examine interactions between family history and smoking, age at menarche or body mass index (BMI). DESIGN, SETTING AND POPULATION: Population-based nationwide cohort study. METHODS: Using data from the Korean National Health Insurance and Screening Programme databases on kinship, healthcare utilisation, lifestyle and anthropometrics, we identified 2 109 288 women with full siblings and their environmental risk factors from 2002 to 2018. Familial risks were estimated using Cox proportional-hazards models, represented as incidence risk ratios (IRR) with 95% CI. Interaction between family history and smoking, age at menarche or BMI were assessed on an additive scale. MAIN OUTCOME MEASURES: IRR of endometriosis among women with and without affected siblings. RESULTS: From 19 195 women with affected siblings, 1126 developed endometriosis with an incidence of 35.45/10 000 person-years. Familial risk of endometriosis with versus without affected siblings was increased to IRR 2.75 (95% CI 2.25-3.36), and the highest risk was with affected twins (IRR 6.98; 95% CI 4.19-11.62). Women with both a family history and either smoking, early menarche or low BMI had a significantly higher risk of endometriosis compared with the general population and can be regarded as a high-risk group, the IRRs were 4.28 (95% CI 2.43-7.55), 3.47 (95% CI 2.82-4.26) and 3.09 (95% CI 2.68-3.56), respectively. Substantial effect modification of the associations was noted by smoking and early menarche, as their combined risk with family history exceeded the sum of their individual risks, which was also statistically significant. CONCLUSION: Genetic factors are the primary contributor to the familial aggregation of endometriosis. Significant gene-environment interaction exists between family history and smoking or early menarche. TWEETABLE ABSTRACT: Significant gene-environment interaction exists between family history of endometriosis and smoking or early menarche.

Mutation-specific differences in arrhythmias and drug responses in CPVT patients: simultaneous patch clamp and video imaging of iPSC derived cardiomyocytes.

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited cardiac disease characterized by arrhythmias under adrenergic stress. Mutations in the cardiac ryanodine receptor (RYR2) are the leading cause for CPVT. We characterized electrophysiological properties of CPVT patient-specific induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) carrying different mutations in RYR2 and evaluated effects of carvedilol and flecainide on action potential (AP) and contractile properties of hiPSC-CMs. iPSC-CMs were generated from skin biopsies of CPVT patients carrying exon 3 deletion (E3D) and L4115F mutation in RYR2. APs and contractile movement were recorded simultaneously from the same hiPSC-CMs. Differences in AP properties of ventricular like CMs were seen in CPVT and control CMs: APD90 of both E3D (n = 20) and L4115F (n = 25) CPVT CMs was shorter than in control CMs (n = 15). E3D-CPVT CMs had shortest AP duration, lowest AP amplitude, upstroke velocity and more depolarized diastolic potential than controls. Adrenaline had positive and carvedilol and flecainide negative chronotropic effect in all hiPSC CMs. CPVT CMs had increased amount of delayed after depolarizations (DADs) and early after depolarizations (EADs) after adrenaline exposure. E3D CPVT CMs had the most DADs, EADs, and tachyarrhythmia. Discordant negatively coupled alternans was seen in L4115F CPVT CMs. Carvedilol cured almost all arrhythmias in L4115F CPVT CMs. Both drugs decreased contraction amplitude in all hiPSC CMs. E3D CPVT CMs have electrophysiological properties, which render them more prone to arrhythmias. iPSC-CMs provide a unique platform for disease modeling and drug screening for CPVT. Combining electrophysiological measurements, we can gain deeper insight into mechanisms of arrhythmias.

Antiarrhythmic Effects of Carvedilol and Flecainide in Cardiomyocytes Derived from Catecholaminergic Polymorphic Ventricular Tachycardia Patients.

Mutations in the cardiac ryanodine receptor (RYR2) are the leading cause for catecholaminergic polymorphic ventricular tachycardia (CPVT). In this study, we evaluated antiarrhythmic efficacy of carvedilol and flecainide in CPVT patient-specific induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) carrying different mutations in RYR2. iPSC-CMs were generated from skin biopsies of CPVT patients carrying exon 3 deletion and L4115 or V4653F mutation in RYR2 and of a healthy individual. Ca2+ kinetics and drug effects were studied with Fluo-4 AM indicator. Carvedilol abolished Ca2+ abnormalities in 31% of L4115F, 36% of V4653F, and 46% of exon 3 deletion carrying CPVT cardiomyocytes and flecainide 33%, 30%, and 52%, respectively. Both drugs lowered the intracellular Ca2+ level and beating rate of the cardiomyocytes significantly. Moreover, flecainide caused abnormal Ca2+ transients in 61% of controls compared to 26% of those with carvedilol. Carvedilol and flecainide were equally effective in CPVT iPSC-CMs. However, flecainide induced arrhythmias in 61% of control cells. CPVT cardiomyocytes carrying the exon 3 deletion had the most severe Ca2+ abnormalities, but they had the best response to drug therapies. According to this study, the arrhythmia-abolishing effect of neither of the drugs is optimal. iPSC-CMs provide a unique platform for testing drugs for CPVT.

Bevacizumab combined with docetaxel, oxaliplatin, and capecitabine, followed by maintenance with capecitabine and bevacizumab, as first-line treatment of patients with advanced HER2-negative gastric cancer: A multicenter phase 2 study.

BACKGROUND: The current study was a multicenter, single-arm, phase 2 study performed to investigate the feasibility and efficacy of bevacizumab combined with docetaxel, oxaliplatin, and capecitabine (B-DOC) in patients with advanced human epidermal growth factor receptor 2 (HER2)-negative, previously untreated, gastric or gastroesophageal adenocarcinoma. METHODS: Tumor HER2 status was determined centrally. Patients received 6 cycles of bevacizumab at a dose of 7.5 mg/kg, docetaxel at a dose of 50 mg/m(2) , and oxaliplatin at a dose of 100 mg/m(2) (all on day 1) combined with capecitabine at a dose of 850 mg/m(2) twice daily (days 1-14) every 3 weeks followed by maintenance with capecitabine and bevacizumab in patients with disease control. The primary objective was to demonstrate a progression-free survival (PFS) of >6.5 months, according to the 95% confidence interval (95% CI). Secondary endpoints included safety, objective response rate, overall survival (OS), analyses of circulating tumor cells (CTCs), and pharmacogenetic analyses. RESULTS: Sixty eligible patients were enrolled. The median PFS was 8.3 months (95% CI, 7.2-10.9 months). The objective response rate was 70% (95% CI, 55%-83%) and the disease control rate was 96% (95% CI, 85%-99%). The median OS was 12.0 months (95% CI, 10.2-16.1 months). According to CTC-AE v4.0, the most common treatment-related grade ≥3 adverse events were neutropenia (20%), leukocytopenia (18%), diarrhea (15%), and nausea/vomiting (15%). The presence of CTCs at baseline was strongly predictive of PFS (hazard ratio [HR], 3.8; P =.007) and OS (HR, 3.4; P =.014). The methylenetetrahydrofolate reductase (MTHFR) 677C>T genotype was strongly associated with PFS (HR, 4.7 for TT vs CC or CT; P =.0007) and OS (HR, 5.9; P =.0001). CONCLUSIONS: The B-DOC regimen plus maintenance was feasible and active. CTCs were found to be prognostic in patients treated with B-DOC. Docetaxel-based triplet chemotherapy as a backbone for targeted therapies is feasible and deserves further study. Cancer 2016;122:1434-1443. © 2016 American Cancer Society.

Trastuzumab and bevacizumab combined with docetaxel, oxaliplatin and capecitabine as first-line treatment of advanced HER2-positive gastric cancer: a multicenter phase II study.

OBJECTIVE: To investigate the efficacy of bevacizumab and trastuzumab combined with docetaxel, oxaliplatin, and capecitabine (B-DOCT) as first-line treatment of advanced human epidermal growth factor receptor 2 (HER2)-positive gastric cancer (GC). METHODS: In this multicentre, single-arm, phase II study, tumor HER2 status was determined centrally prior to treatment. Patients with advanced HER2-positive adenocarcinoma of the stomach or gastroesophageal junction (immunohistochemistry 3+ or immunohistochemistry 2+/silver in-situ hybridization positive) were treated with six cycles of bevacizumab 7.5 mg/kg (day 1), docetaxel 50 mg/m(2) (day 1), oxaliplatin 100 mg/m(2) (day 1), capecitabine 850 mg/m(2) b.i.d. (days 1-14), and trastuzumab 6 mg/kg (day 1) every three weeks, followed by maintenance with bevacizumab, capecitabine, and trastuzumab until disease progression. The primary objective was to demonstrate an improvement of progression-free survival (PFS) to >7.6 months (observed in the ToGA trial) determined according to the lower limit of the 95 % confidence interval (CI). Secondary endpoints were safety, objective response rate (ORR), and overall survival (OS). RESULTS: Twenty-five patients with HER2-positive tumors were treated with B-DOCT between March 2011 and September 2014. At a median follow-up of 17 months, median PFS was 10.8 months (95%CI: 9.0-NA), OS was 17.9 months (95%CI: 12.4-NA). One-year PFS and OS were 52 % and 79 %, respectively. The ORR was 74 % (95%CI: 52-90 %). Two patients became resectable during treatment with B-DOCT and achieved a pathological complete response. The most common treatment-related grade ≥ 3 adverse events were: neutropenia (16 %), diarrhoea (16 %), and hypertension (16 %). CONCLUSIONS: B-DOCT is a safe and active combination in HER2-positive GC, supporting further investigations of DOC with HER2/vascular endothelial growth factor (VEGF) inhibition in HER2-positive GC.

Investigating the momentum balance of a plasma pinch: an air-side stereoscopic imaging system for locating probes.

The momentum balance of a plasma pinch in the Reconnection Scaling Experiment (RSX) is examined in three dimensions using several repositionable, insertable probes. A new camera-based system described here triangulates the locations of the probe tips so that their measurements are spatially registered. The optical system locates probes to within ±1.5 mm of their absolute 3D position in the vessel and to within ±0.7 mm relative to other probes, on the order of the electron inertial length (1-2 mm).

Work stress and the long QT syndrome: high job strain and effort-reward imbalance at work associated with arrhythmic risk in the long QT syndrome.

OBJECTIVES: To examine whether work stress is associated with a symptomatic status of the long QT syndrome (LQTS). METHODS: The sample comprised 173 KCNQ1, KCNH2, or SCN5A gene mutation carriers (70 symptomatic) and control groups of 203 relatives without the family mutation, and of 1209 population-based young Finns control subjects. Work stress was assessed using the Job Content Questionnaire and Occupational Stress Questionnaire. RESULTS: We found an association between the occurrence of symptoms in the LQTS and high work stress, higher job demands/effort, lower job control, and lower rewards compared with control subjects. We also found that symptomatic LQTS mutation carriers had higher work stress than asymptomatic LQTS mutation carriers. CONCLUSIONS: Higher work stress is related to arrhythmic risk in the LQTS. It may be useful to incorporate assessment of work conditions and stress interventions into management of high-risk patients.

The return of unexpected research results in a biobank study and referral to health care for heritable long QT syndrome.

BACKGROUND: In this study, we examined how biobank study participants, who were found to have long QT syndrome (LQTS), a potentially life-threatening but treatable cardiac arrhythmia condition, experienced the process of disclosure of unexpected results and referral to health care. METHODS: All 27 subjects with a LQTS mutation finding were asked to complete a questionnaire. Four participants did not uptake the re-testing and 5 others did not respond to the questionnaire. We received 17 questionnaires from 6 males and 11 females, aged 46-82; 5 of them were also willing to participate in qualitative interviews. RESULTS: Of the respondents, 16/17 had experienced the process of receiving the results as positive and useful, especially if they had had symptoms. One respondent experienced the process negatively due to concerns related to informing her children. All respondents felt that genetic results should be reported back to the participants, while 2 indicated that this should occur only in the case of treatable conditions. Respondents had informed all of their children about the genetic condition, except 2 minors. CONCLUSIONS: The respondents from a population biobank study who were informed about an unexpected genetic finding evaluated this process as mainly positive. They considered that delivering genetic information about a life-threatening but actionable condition has more beneficial than adverse consequences. The feedback policy for biobanks should include how and who is informed, advise treatment or care pathways for actionable findings, and it should also include suitable options for those who do not want to know about such findings.

A history of stressful life events, prolonged mental stress and arrhythmic events in inherited long QT syndrome.

OBJECTIVE: To examine whether a history of stressful life events and prolonged mental stress are associated with arrhythmic events in inherited long QT syndrome (LQTS). METHODS: Participants who had a molecularly established mutation of KCNQ1, KCNH2 or SCN5A channel and were thus diagnosed as patients with LQT1, LQT2 and LQT3 (n=566), accordingly. The control group consisted of their 614 non-affected relatives. A history of stressful life events was indexed by the major stressful life events. Prolonged mental stress was indexed by vital exhaustion (VE), which was measured with the Maastricht Questionnaire. RESULTS: Multinomial logistic regression analysis including patients with LQTS with and without arrhythmic events and the control subjects showed an age- and sex-adjusted association of stressful life events OR=1.15 (95% CI 1.08 to 1.22) and VE (OR=3.33 (95% CI 1.63 to 6.78)) with symptomatic status of LQTS. Symptomatic patients with LQTS had experienced more stressful life events (OR=1.16 (95% CI 1.08 to 1.24)) and the level of VE (OR=3.40 (95% CI 1.44 to 8.03)) was more than three times higher among patients with LQTS with arrhythmic events than in asymptomatic LQTS mutation carriers. The association between stressful life events and arrhythmic events was independent of age, sex, specifically focused medication and LQTS subtype. CONCLUSIONS: A history of stressful life events and prolonged mental stress are associated with arrhythmic events in LQTS in this large sample of molecularly defined patients with LQTS. It is important for future studies to assess how strong these predisposing factors are for arrhythmic events in LQTS.

Common candidate gene variants are associated with QT interval duration in the general population.

OBJECTIVES: QT interval prolongation is associated with increased risk of sudden cardiac death at the population level. As 30-40% of the QT-interval variability is heritable, we tested the association of common LQTS and NOS1AP gene variants with QT interval in a Finnish population-based sample. METHODS: We genotyped 12 common LQTS and NOS1AP genetic variants in Health 2000, an epidemiological sample of 5043 Finnish individuals, using Sequenom MALDI-TOF mass spectrometry. ECG parameters were measured from digital 12-lead ECGs and QT intervals were adjusted for age, gender and heart rate with a nomogram (Nc) method derived from the present study population. RESULTS: The KCNE1 D85N minor allele (frequency 1.4%) was associated with a 10.5 ms (SE 1.6) or 0.57 SD prolongation of the adjusted QT(Nc) interval (P=3.6 x 10(-11)) in gender-pooled analysis. In agreement with previous studies, we replicated the association with QT(Nc) interval with minor alleles of KCNH2 intronic SNP rs3807375 [1.6 ms (SE 0.4) or 0.08 SD, P=4.7 x 10(-5)], KCNH2 K897T [-2.6 ms (SE 0.5) or -0.14 SD, P=2.1 x 10(-7)] and NOSA1P variants including rs2880058 [4.0 ms (SE 0.4) or 0.22 SD, P=3.2 x 10(-24)] under additive models. CONCLUSIONS: We demonstrate that each additional copy of the KCNE1 D85N minor allele is associated with a considerable 10.5 ms prolongation of the age-, gender- and heart rate-adjusted QT interval and could thus modulate repolarization-related arrhythmia susceptibility at the population level. In addition, we robustly confirm the previous findings that three independent KCNH2 and NOSA1P variants are associated with adjusted QT interval.

Passive transfer of immunoglobulin G and preweaning health in Holstein calves fed a commercial colostrum replacer.

The objective of this study was to describe passive transfer of IgG and preweaning health in newborn calves fed a commercially available plasma-derived colostrum replacement (CR) product or maternal colostrum (MC). Twelve commercial Holstein dairy farms enrolled singleton newborn heifer calves to be fed fresh MC (n = 239 calves) or one dose of CR containing 125 g of Ig (n = 218 calves) as the first colostrum feeding. For 7 of these farms that routinely provided a second feeding of 1.9 L of MC to their calves 8 to 12 h after the first colostrum feeding, calves assigned to the CR treatment group were offered a second feeding consisting of 1.9 L of commercial milk replacer supplemented with one dose of a commercially available plasma-derived colostrum supplement, containing 45 g of Ig per dose, 8 to 12 h after the first colostrum feeding. A blood sample was collected from all calves between 1 to 8 d of age for serum IgG and total protein (TP) determination, and records of all treatment and mortality events were collected until weaning. Serum IgG and TP concentrations were significantly higher in calves fed MC (IgG = 14.8 +/- 7.0 mg/mL; TP = 5.5 +/- 0.7 g/dL) compared with calves fed CR (IgG = 5.8 +/- 3.2 mg/mL; TP = 4.6 +/- 0.5 g/dL). The proportion of calves with failure of passive transfer (serum IgG <10.0 mg/mL) was 28.0 and 93.1% in the MC and CR treatment groups, respectively. Though a trend was present, the proportion of calves treated for illness was not statistically different for calves fed MC (51.9%) vs. CR (59.6%). Total number of days treated per calf (MC = 1.7; CR = 2.0), treatment costs per calf (MC = $10.84; CR = $11.88), and proportion of calves dying (MC = 10.0%; CR = 12.4%) was not different between the 2 colostrum treatment groups. The mean serum total protein concentration predictive of successful passive transfer (serum IgG = 10 mg/mL) was 5.0 g/dL in calves fed MC or CR. Long-term follow-up of these calves (to maturity) is ongoing to describe the effects of feeding CR on longevity, productivity, risk for Johne's disease, and economics.

Response of the QT interval to mental and physical stress in types LQT1 and LQT2 of the long QT syndrome.

OBJECTIVE: To study and compare the effects of mental and physical stress on long QT syndrome (LQTS) patients. DESIGN: Case-control study. MAIN OUTCOME MEASURES: QT intervals were measured from lead V3. Serum potassium and plasma catecholamine concentrations were also monitored. PATIENTS: 16 patients with type 1 LQTS (LQT1), 14 with type 2 LQTS (LQT2), both groups asymptomatic, and 14 healthy control subjects. INTERVENTIONS: Three types of mental stress tests and a submaximal exercise stress test. RESULTS: Heart rate responses to mental stress and exercise were similar in all groups. During mental stress, the mean QT interval shortened to a similar extent in controls (-29 ms), LQT1 patients (-34 ms), and LQT2 patients (-30 ms). During exercise, the corresponding QT adaptation to exercise stress was more pronounced (p < 0.01) in healthy controls (-47 ms) than in LQT1 (-38 ms) or LQT2 patients (-38 ms). During exercise changes in serum potassium concentrations were correlated to changes in QT intervals in controls, but not in LQTS patients. LQT1 and LQT2 patients did not differ in serum potassium, catecholamine or heart rate responses to mental or physical stress. CONCLUSIONS: QT adaptation to mental and exercise stress in healthy people and in patients with LQTS is different. In healthy people QT adaptation is more sensitive to physical than to mental stress while no such diverging pattern was seen in asymptomatic LQTS patients.

Mutations of the cardiac ryanodine receptor (RyR2) gene in familial polymorphic ventricular tachycardia.

BACKGROUND: Familial polymorphic ventricular tachycardia is an autosomal-dominant, inherited disease with a relatively early onset and a mortality rate of approximately 30% by the age of 30 years. Phenotypically, it is characterized by salvoes of bidirectional and polymorphic ventricular tachycardias in response to vigorous exercise, with no structural evidence of myocardial disease. We previously mapped the causative gene to chromosome 1q42-q43. In the present study, we demonstrate that patients with familial polymorphic ventricular tachycardia have missense mutations in the cardiac sarcoplasmic reticulum calcium release channel (ryanodine receptor type 2 [RyR2]). METHODS AND RESULTS: In 3 large families studied, 3 different RyR2 mutations (P2328S, Q4201R, V4653F) were detected and shown to fully cosegregate with the characteristic arrhythmic phenotype. These mutations were absent in the nonaffected family members and in 100 healthy controls. In addition to identifying 3 causative mutations, we identified a number of single nucleotide polymorphisms that span the genomic structure of RyR2 and will be useful for candidate-based association studies for other arrhythmic disorders. CONCLUSIONS: Our data illustrate that mutations of the RyR2 gene cause at least one variety of inherited polymorphic tachycardia. These findings define a new entity of disorders of myocardial calcium signaling.

A founder mutation of the potassium channel KCNQ1 in long QT syndrome: implications for estimation of disease prevalence and molecular diagnostics.

OBJECTIVES: We took advantage of the genetic isolate of Finns to characterize a common long QT syndrome (LQTS) mutation, and to estimate the prevalence of LQTS. BACKGROUND: The LQTS is caused by mutations in different ion channel genes, which vary in their molecular nature from family to family. METHODS: The potassium channel gene KCNQ1 was sequenced in two unrelated Finnish patients with Jervell and Lange-Nielsen syndrome (JLNS), followed by genotyping of 114 LQTS probands and their available family members. The functional properties of the mutation were studied using a whole-cell patch-damp technique. RESULTS: We identified a novel missense mutation (G589D or KCNQ1-Fin) in the C-terminus of the KCNQ1 subunit. The voltage threshold of activation for the KCNQ1-Fin channel was markedly increased compared to the wild-type channel. This mutation was present in homozygous form in two siblings with JLNS, and in heterozygous form in 34 of 114 probands with Romano-Ward syndrome (RWS) and 282 family members. The mean (+/- SD) rate-corrected QT intervals of the heterozygous subjects (n = 316) and noncarriers (n = 423) were 460 +/- 40 ms and 410 +/- 20 ms (p < 0.001), respectively. CONCLUSIONS: A single missense mutation of the KCNQ1 gene accounts for 30% of Finnish cases with LQTS, and it may be associated with both the RWS and JLNS phenotypes of the syndrome. The relative enrichment of this mutation most likely represents a founder gene effect. These circumstances provide an excellent opportunity to examine how genetic and nongenetic factors modify the LQTS phenotype.

Survey of the coding region of the HERG gene in long QT syndrome reveals six novel mutations and an amino acid polymorphism with possible phenotypic effects.

Analysis of the entire coding region of the HERG gene of 39 Finnish LQTS patients revealed eight mutations, six of which are hitherto unreported. All these mutations are located in the evolutionarily conserved regions of HERG, including the transmembrane domains (P451L, Y569H, 1631delAG, G584S, G601S, T613M) and the cytoplasmic N-terminus (453delC, R176W) of the channel. Our present and earlier results suggest that the LQT2 subtype accounts for approximately 20-30% of LQTS cases in Finland. We also report the first common amino acid polymorphism (K897T) of the HERG channel, with allele frequencies of 0.84 and 0.16. Investigation of 170 genetically homogenous LQT1 patients suggests that this polymorphism may influence QT interval in female individuals.

Homozygosity for a HERG potassium channel mutation causes a severe form of long QT syndrome: identification of an apparent founder mutation in the Finns.

OBJECTIVES: We studied the clinical characteristics and molecular background underlying a severe phenotype of long QT syndrome (LQTS). BACKGROUND: Mutations of cardiac ion channel genes cause LQTS, manifesting as increased risk of ventricular tachycardia and sudden death. METHODS: We studied two siblings showing prolonged QT intervals corrected for heart rate (QTc), their asymptomatic parents with only marginally prolonged QTc intervals and their family members. The potassium channel gene HERG was screened for mutations by deoxyribonucleic acid sequencing, and the electrophysiologic consequences of the mutation were studied in vitro using the whole-cell patch-clamp technique. RESULTS: A novel missense mutation (L552S) in the HERG channel, present in the homozygous state in the affected siblings and in the heterozygous state in their parents, as well as in 38 additional subjects from six LQTS families, was identified. One of the homozygous siblings had 2:1 atrioventricular block immediately after birth, and died at the age of four years after experiencing unexplained hypoglycemia. The other sibling had an episode of torsade de pointes at the age of two years. The mean QTc interval differed significantly (p < 0.001) between heterozygous symptomatic mutation carriers (500 +/- 59 ms), asymptomatic mutation carriers (452 +/- 34 ms) and noncarriers (412 +/- 23 ms). When expressed in vitro, the HERG-L552S formed functional channels with increased activation and deactivation rates. CONCLUSIONS: Our data demonstrate that homozygosity for a HERG mutation can cause a severe cardiac repolarization disorder without other phenotypic abnormalities. Absence of functional HERG channels appears to be one cause for intrauterine and neonatal bradycardia and 2:1 atrioventricular block.