Adenosine-induced sinus tachycardia in a patient with Myotonic Dystrophy type 1

We report the case of a 32-year-old man with Myotonic Dystrophy type 1 showing adenosine-induced sinus tachycardia during transesophageal electrophysiological evaluation.Key words: sinus tachycardia, adenosine, proarrhythmic effect, myotonic dystrophy     

Gender effect on onset,prevalence and surgical treatment of cataract in patients with Myotonic Dystrophy type 1

Myotonic Dystrophy type 1 (DM1) is the most common muscular dystrophy in adults, affecting 1:8000 individuals. It is a multi-systemic disorder involving muscle, heart, endocrine and respiratory apparatus and eye. The eye symptoms can include ptosis, external ophthalmoplegia, epiphora, and early onset cataracts. Cataracts occur at a much earlier age (usually between 30 and 40) than the general population, where females are usually affected more than men. We studied gender differences in cataract prevalence and treatment age in 243 DM1 patients (134 M; 109 F), aged 18 to 70 years, who were subsequently screened at routine follow-up. For each patient, information was collected on age, sex, CTG expansion, age of cataract onset, and age at cataract surgery, when available.Seventy-three patients, 30 females and 43 males, had cataracts, at a mean age of onset of 41.14 ± 12.64 in females, and 40.36 ± 10.03 in males. Sixty-nine of them underwent cataract surgery, males at an earlier age than females (42.8 ± 9.8 years versus 47.3 ± 12.6 years) and in 52.5% of cases before the age of 40, compared to 17.2% of females. The difference was statistically significant. The assumption that females in general and those with DM1 in particular develop cataracts more frequently and earlier than males is not confirmed, at least in this study. A possible explanation for these results could be related to non-advanced age, the protective role of estrogen and the lower prevalence of smoking in the study population.Key words: Myotonic Dystrophy type 1, Steinert disease, gender, cataract, cataract surgery, prevalence     

Right atrial preference pacing algorithm in the prevention of paroxysmal atrial fibrillation in myotonic dystrophy type 1 patients: a long term follow-up study

Atrial Preference Pacing (APP) is a pacemaker (PM) algorithm that works by increasing the atrial pacing rate to achieve continuous suppression of a spontaneous atrial rhythm and prevent supraventricular tachyarrhythmias. We have previously shown that atrial preference pacing may significantly reduce the number and the duration of AF episodes in myotonic dystrophy type 1 (DM1) patients who are paced for standard indications.However, the role that APP therapies play in the prevention of AF in a long-term period remains still unclear. Aim of the present prospective study was to evaluate whether this beneficial effect is maintained for 24-months follow-up period.To this aim, 50 patients with Myotonic Dystrophy type 1 who underwent dual-chamber PM implantation for first- and second- degree atrioventricular block, were consecutively enrolled and followed for 2 years. One month later the stabilization period, after the implantation, they were randomized to APP algorithm programmed OFF or ON for 6 months each, using a cross-over design, and remained in the same program for the second year. The results showed that while the number of AF episodes during active treatment (APP ON phases) was lower than that registered during no treatment (APP OFF phases), no statistically significant difference was found in AF episodes duration between the two phases. Furthermore, during the APP OFF and APP ON phases, the percentage of atrial pacing was 0 and 99%, respectively, while the percentage of ventricular pacing did not show differences statistically significant (11 vs. 9%, P = 0.2). Atrial premature beats were significantly higher during APP OFF phases than during APP ON phases. Lead parameters remained stable over time and there were no lead-related complications. Based on these 24-months follow-up data, we can conclude that, in DM1 patients who underwent dual-chamber PM implantation, APP is an efficacy algorithm for preventing paroxysmal AF even in long term periods.Key words: myotonic dystrophy, atrial preference pacing, atrial fibrillation     

Ventricular fibrillation induced by coagulating mode bipolar electrocautery during pacemaker implantation in Myotonic Dystrophy type 1 patient

The occurrence of ventricular fibrillation, induced by bipolar electrocautery during elective dual chamber pacemaker implantation, is reported in a patient affected by Myotonic Distrophy type 1 with normal left ventricular ejection fractionKey words: ventricular fibrillation, bipolar electrocautery, pacemaker implantation, Myotonic Dystrophy type 1     

Far field R-wave sensing in Myotonic Dystrophy type 1: right atrial appendage versus Bachmann's bundle region lead placement

Aim of the present study was to investigate far field R-wave sensing (FFRS) timing and characteristics in 34 Myotonic Dystrophy type 1 (DM1) patients undergoing dual chamber pacemaker implantation, comparing Bachmann''s bundle (BB) stimulation (16 patients) site with the conventional right atrial appendage (RAA) pacing site (18 patients). All measurements were done during sinus rhythm and in supine position, with unipolar (UP) and bipolar (BP) sensing configuration. The presence, amplitude threshold (FFRS trsh) and FFRS timing were determined. There were no differences between both atrial sites in the Pmin and Pmean values of sensed P-wave amplitudes, as well as between UP and BP sensing configurations. The FFRS trsh was lower at the BB region in comparison to the RAA site. The mean BP FFRS trsh was significantly lower than UP configuration in both atrial locations. There were no significant differences in atrial pacing threshold, sensing threshold and atrial lead impedances at the implant time and at FFRS measurements. Bachmann''s bundle area is an optimal atrial lead position for signal sensing as well as conventional RAA, but it offers the advantage of reducing the oversensing of R-wave on the atrial lead, thus improving functioning of standard dual chamber pacemakers in DM1 patients.Key words: far field, oversensing, far field R-wave sensing, myotonic dystrophy type 1, atrial lead, Bachmann''s bundle     

The heart and cardiac pacing in Steinert disease

Myotonic dystrophy (Dystrophia Myotonica, DM) is the most frequently inherited neuromuscular disease of adult life. It is a multisystemic disease with major cardiac involvement. Core features of myotonic dystrophy are myotonia, muscle weakness, cataract, respiratory failure and cardiac conduction abnormalities. Classical DM, first described by Steinert and called Steinert''s disease or DM1 (Dystrophia Myotonica type 1) has been identified as an autosomal dominant disorder associated with the presence of an abnormal expansion of a CTG trinucleotide repeat in the 3'' untranslated region of DMPK gene on chromosome 19. This review will mainly focus on the various aspects of cardiac involvement in DM1 patients and the current role of cardiac pacing in their treatment.Key words: myotonic dystrophy type 1, arrhythmias, cardiac pacing     

The effect of conversion type on P wave dispersion in patients with atrial fibrillation

AIM: The aim of this study was to investigate whether conversion type of atrial fibrillation (AF) to sinus rhythm affects the P wave dispersion (PD) in patients with AF. METHODS: Based on conversion type, 95 consecutive patients with AF <3 months were divided into 3 groups: spontaneous cardioversion (SC) (N.=33, mean age: 60.6+/-11.6 years), pharmacologic cardioversion (PC) (N.=32, mean age: 59.2+/-9.6 years) and electrical cardioversion (EC) (N.= 30, mean age: 65.3+/-10.6 years). P wave duration (maximum and minimum) were measured in 12-lead ECG, and PD was calculated. RESULTS: Left atrial diameter and AF duration were significantly higher in EC (43.6+/-4.8 mm and 794.1+/-815.1 h) than SC (38.5+/-3.9 mm and 13.8+/-18.3 h) and PC (40.9+/-4.5 mm and 65.3+/-148.5 h) groups (P<0.01). P maximum was much longer in EC group compared with SC and PC group (121.6+/-9.7, 108.4+/-6.4 and 115.8+/-8.6 ms, P=0.01, respectively). There was a significant difference in PD among SC, PC and EC groups (44.4+/-9.2, 49.5+/-8.7 and 53.5+/-8.8 ms; P=0.005, respectively). PD correlated with AF duration (r=0.36, P=0.03), left atrial diameter (r=0.45, P=0.002) and conversion type (r=0.29, P=0.03). However, there was no significant association between PD and conversion type in multivariate analysis. The prolonged PD resulted from AF duration (P=0.01) and the left atrial size P=0.001). CONCLUSION: This study suggests that conversion type of AF to sinus rhythm has no effect on P wave duration and independent of AF duration and the left atrial diameter.     

心房颤动患者左房电压基质改变的比较观察

目的探讨持续性心房颤动(简称房颤)患者左房电压基质情况以指导持续性房颤的导管射频消融。方法80例持续性房颤(Pers-AF组)、30例阵发性房颤(Paro-AF组)及10例左侧旁道患者(对照组)在窦性心律下完成左房电压基质和激动标测。左房分为7个区域进行统计分析电压、区域传导激动指数和标测面积。结果左房低电压区和/或疤痕区在房颤患者中检出阳性率仅为12.7%(14/110,Paro-AF组2例,Pers-AF组12例),PersAF和Paro-AF两组低电压区和/或疤痕区的阳性率比较无统计学差异(15%vs 6.7%,P=0.34)。相比于对照组,其他两组患者左房平均电压显著低,大部分区域激动传导缓慢。此外,Pers-AF组左房电压降低较Paro-AF组患者显著。结论房颤患者左房平均电压显著降低并传导缓慢,以Pers-AF患者为甚,低电压区和/或疤痕区可能是持续性房颤维持基质。     

The effect of fibrinogen concentrate and factor XIII on thromboelastometry in 33% diluted blood with albumin,gelatine, hydroxyethyl starch or saline in vitro

Background

Fluid replacement results in dilutional coagulopathy. We investigated the potential role of fibrinogen, factor XIII and a combination of both to reverse dilutional coagulopathy, assessed by thromboelastometry (ROTEM ^® ).

Material and methods

Blood samples from healthy volunteers were analysed undiluted and after 33% dilution in vitro with albumin, gelatine, 130/0.4 hydroxyethyl starch or saline. Diluted samples were incubated with fibrinogen (3 g/70 kg bodyweight equivalent), factor XIII (10,000 IU/70 kg bodyweight equivalent), or a combination of both. Measurements were performed using an extrinsic activated assay (EXTEM ^® ) and a functional fibrin polymerisation test (FIBTEM ^® ).

Results

Compared with baseline, EXTEM clotting time increased with hydroxyethyl starch, exceeding the upper limit of the reference value. Albumin prolonged clotting time within normal limits. Gelatine did not change clotting time, and saline reduced clotting time. Clot formation time increased in colloids only. Maximum clot firmness of both EXTEM and FIBTEM decreased with all fluids, but was less pronounced in saline. Incubation with fibrinogen had no effect on EXTEM maximum clot firmness but improved FIBTEM maximum clot firmness in saline (P <0.001) and albumin (P <0.05), but not gelatine and hydroxyethyl starch). Factor XIII had no effect on any EXTEM and FIBTEM maximum clot firmness results. Fibrinogen and factor XIII combined did not improve EXTEM maximum clot firmness. Fibrinogen and factor XIII did not change FIBTEM maximum clot firmness in hydroxyethyl starch but improved FIBTEM maximum clot firmness in albumin (P <0.001), gelatine (P <0.01) and saline (P <0.001).

Discussion

ROTEM parameters in dilutional coagulopathy in vitro cannot be improved with factor XIII alone in any tested diluent. The combination of fibrinogen and factor XIII is highly effective in raising FIBTEM maximum clot firmness after dilution with albumin, gelatine and saline back to normal values, but is ineffective in 130/0.4 hydroxyethyl starch.     

Effects of atrial fibrillation substrate and spatiotemporal organization on atrial defibrillation thresholds

BACKGROUND: We previously showed that canine models of atrial fibrillation (AF) have different substrates (either structural or electrical) that lead to differences in AF characteristics. OBJECTIVE: The purpose of this study was to determine whether the differences in AF characteristics also would lead to differences in atrial defibrillation thresholds (ADFTs). METHODS: Dogs were divided into five groups: control; MR-mitral regurgitation for 5 weeks; CHF-congestive heart failure for 4 weeks; RAP-rapid atrial pacing for 6 weeks; and METH-acetyl-beta-methylcholine acutely administered. A cross-sectional area of the left atrium was calculated, and AF was induced with rapid atrial pacing. Biphasic shocks with a pulse width of 3/3 ms were delivered through specially constructed shocking catheters with a surface area of 3.7 cm(2) that were placed in the right and left atria. An up-down-up protocol was used to determine the 50% ADFT threshold (ADFT(50)). A wide-bipole AF signal was digitally filtered, and a fast Fourier transform was calculated over a 2-second window every 1 second. The dominant frequency was determined, and the organization index was calculated as the ratio of the area under the dominant peak and its harmonics to the total area of the spectrum. RESULTS: For left atrial size, the CHF and MR groups had a significantly larger atria than did control. ADFT(50) for control, MR, CHF, RAP, and METH groups were 160 +/- 30 V, 120 +/- 50 V, 132 +/- 20 V, 668 +/- 205 V, and 593 +/- 128 V, respectively (analysis of variance, P <.0001). Dominant frequencies were significantly higher and organization indexes significantly lower in the RAP and METH models compared with the other models. CONCLUSION: RAP and METH canine models had a significantly higher ADFT(50) compared with the other AF models. The increase in ADFT(50) in these models corresponded with higher global dominant frequencies and lower measured organization indexes.     

硫氮(卓)酮治疗阵发性心房颤动的长期临床观察

目的 :探讨硫氮酮对阵发性心房颤动 (房颤 )的治疗效果。方法 :选择 6 2例阵发性房颤患者 ,随机分为硫氮酮组 (31例 )和对照组 (31例 ) ,随访 3年 ,观察房颤年发作次数、持续时间和转变为持续性房颤的情况。结果 :①硫氮酮明显减少房颤年发作次数、持续时间 (P <0 .0 1) ,但用药后 1～ 2年间差异无显著性意义(P >0 .0 5 ) ;②对照组房颤年发作次数、持续时间逐年增加 ,年与年之间差异有非常显著性意义 (P <0 .0 1) ;③随访期间 ,对照组有 6例而硫氮酮组无一例转变为持续性房颤 ,两组间差异有显著性意义 (P <0 .0 5 )。结论 :硫氮酮可明显减少阵发性房颤发作次数和持续时间 ,在阻止其转变为持续性房颤也有一定的作用 ,推测与硫氮酮阻止房颤电重构的发生有关     

β1肾上腺素能受体自身抗体表达增强对心房颤动及心房电重构的影响

目的探讨β1肾上腺素能受体自身抗体(β1AR)表达增强对心房颤动(简称房颤)及心房电重构的影响。方法 24只新西兰大白兔随机分为对照组(Con组)和β1AR组。β1AR组给予2 mgβ1受体细胞外第二环功能表位肽段与佐剂背部皮下多点注射,对照组给予佐剂背部皮下多点注射。每2周注射1次,共4次。于0、2、4、6 W采耳缘静脉血,离心取血清通过酶联免疫吸附测定血清中抗体滴度,验证造模是否成功。每只兔子在免疫前后,采用S_1S_2递减刺激测量心房有效不应期(AERP),通过Burst刺激测量房颤诱发率和持续时间。免疫结束后取心房肌组织进行蛋白免疫印记法检测各组内离子通道蛋白(Kir3.1及Cav1.2)和缝隙连接蛋白(Cx43和Cx40)总量的表达变化,逆转录聚合酶链反应分析上述指标各组内mRNA的表达变化。结果①与0 w比较,β1AR组在2、4和6 w血清中β1AR水平逐渐增加(P<0.05),而Con组内各个时间点血清中β1AR水平无差异(P>0.05);与Con组相比,除0 w两组比较无差异外,其余β1AR组血清中β1AR水平高于Con组(P<0.05)。②β1AR组免疫后较免疫前AERP缩短[(65±8.5)ms vs (116±23.4)ms,P<0.05],平均心率显著增快[(290±35.3)次/分vs (187±31.1)次/分,P<0.05];与Con组相应时间比较,β1AR组免疫后均出现AERP缩短[(65±8.5) ms vs (116±25.3)ms,P<0.05]和平均心率增快[(290±35.3)次/分vs (198±13.7)次/分,P<0.05]。③β1AR组免疫后较免疫前房颤诱发率增加[83.3%(10/12) vs 0(0/12),P<0.05]及持续时间延长[(24.66±40.92)s vs (0±0)s,P<0.05];与Con组相应时间比较,β1AR组房颤诱发率显著增加[83.3%(10/12) vs 0(0/12),P<0.05]及持续时间延长[(24.66±40.92)s vs (0±0)s,P<0.05];④与Con组相比,β1AR组Cx43和Cav1.2蛋白水平及mRNA水平显著降低(P<0.05)。Kir3.1及Cx40蛋白水平及mRNA含量显著升高(P<0.05)。结论β1AR表达增强能缩短AERP,增加房颤易感性和持续时间,通过改变离子通道特性造成心房肌电重构,促进房颤的发生和维持。     

Cardiac resynchronization improves heart failure in one patient with Myotonic Dystrophy type 1. A case report

We report an improvement in symptoms of heart failure, a reduced left ventricular dysfunction and induced reverse remodelling in one patient with Myotonic Dystrophy type 1, showing an early onset ventricular dysfunction secondary to a complete left bundle branch block (LBBB) who underwent cardioverter defibrillator CRT (ICD- CRT) implantation.Key words: myotonic dystrophy, cardiac resynchronization therapy, sudden death