Case report
The proarrhythmic effect of cardiac resynchronization therapy: An issue that should be borne in mind
Terapêutica de ressincronização cardíaca e efeito pró-arrítmico: um problema que deve ser lembrado
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class="elsevierStyleSup">b</span>" "identificador" => "aff0010" ] ] ] 8 => array:3 [ "nombre" => "Rui" "apellidos" => "Ferreira" "referencia" => array:1 [ 0 => array:2 [ "etiqueta" => "<span class="elsevierStyleSup">b</span>" "identificador" => "aff0010" ] ] ] ] "afiliaciones" => array:2 [ 0 => array:3 [ "entidad" => "Serviço de Cardiologia, Hospital de Santarém, Santarém, Portugal" "etiqueta" => "a" "identificador" => "aff0005" ] 1 => array:3 [ "entidad" => "Serviço de Cardiologia, Hospital Santa Marta, Centro Hospitalar de Lisboa Central, Lisboa, Portugal" "etiqueta" => "b" "identificador" => "aff0010" ] ] "correspondencia" => array:1 [ 0 => array:3 [ "identificador" => "cor0005" "etiqueta" => "⁎" "correspondencia" => "Corresponding author." ] ] ] ] "titulosAlternativos" => array:1 [ "pt" => array:1 [ "titulo" => "Terapêutica de ressincronização cardíaca e efeito pró-arrítmico: um problema que deve ser lembrado" ] ] "resumenGrafico" => array:2 [ "original" => 0 "multimedia" => array:7 [ "identificador" => "fig0020" "etiqueta" => "Figure 4" "tipo" => "MULTIMEDIAFIGURA" "mostrarFloat" => true "mostrarDisplay" => false "figura" => array:1 [ 0 => array:4 [ "imagen" => "gr4.jpeg" "Alto" => 1735 "Ancho" => 1667 "Tamanyo" => 94234 ] ] "descripcion" => array:1 [ "en" => "<p id="spar0050" class="elsevierStyleSimplePara elsevierViewall">Chest X-ray, anteroposterior view, showing pacing lead in the posterior vein (blue arrow) and epicardial lead in lateral position (red arrow).</p>" ] ] ] "textoCompleto" => "<span class="elsevierStyleSections"><span id="sec0005" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0025">Introduction</span><p id="par0005" class="elsevierStylePara elsevierViewall">The benefits of cardiac resynchronization therapy (CRT) in reducing mortality and hospitalizations for heart failure (HF), improving NYHA functional class and inducing reverse remodeling have been amply demonstrated in various multicenter trials in the last 10 years, leading to a considerable expansion of indications for biventricular (BiV) pacing.<a class="elsevierStyleCrossRefs" href="#bib0005"><span class="elsevierStyleSup">1–8</span></a></p><p id="par0010" class="elsevierStylePara elsevierViewall">CRT can have adverse effects, most of which are related to procedural complications, infection and system malfunction. In recent years there has also been debate concerning the possible contribution of BiV pacing to the occurrence of complex ventricular arrhythmias.</p></span><span id="sec0010" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0030">Case report</span><p id="par0015" class="elsevierStylePara elsevierViewall">A 58-year-old female patient with controlled mild hypertension, type 2 diabetes and dyslipidemia was being followed in the cardiology outpatient clinic for valvular HF and permanent atrial fibrillation (AF). She had previously undergone mitral valve replacement with a mechanical valve due to severe mitral stenosis.</p><p id="par0020" class="elsevierStylePara elsevierViewall">During follow-up, progressive clinical deterioration was seen to NYHA class III under optimal medical therapy (OMT). The ECG showed QRS interval of 150 ms and complete left bundle branch block. She had no history of ventricular arrhythmias during follow-up. Serial echocardiograms showed steadily worsening global systolic function, ejection fraction (EF) falling from 24% to 13%. Six years after valve replacement surgery, she had severely impaired global systolic function, with left ventricular (LV) end-diastolic diameter of 82 mm, EF estimated at 13% by the modified Simpson's rule, and echocardiographic criteria of intraventricular dyssynchrony, with tissue synchronization imaging showing septal-lateral delay of 100 ms, two-dimensional strain imaging showing radial strain of 448 ms with inferior-anteroseptal delay but no ventricular dyssynchrony (pulmonary and aortic pre-ejection times of 78 ms and 105 ms, respectively). Right ventricular (RV) function was also impaired, with tricuspid annular plane systolic excursion of 5 mm.</p><p id="par0025" class="elsevierStylePara elsevierViewall">A VVIR mode CRT defibrillator (CRT-D) was implanted with the LV lead positioned in a posterolateral vein (<a class="elsevierStyleCrossRef" href="#fig0005">Figure 1</a>) with a different ostium from that of the coronary sinus, the venous system of which was sparse, consisting of small and markedly angulated vessels (<a class="elsevierStyleCrossRef" href="#fig0010">Figure 2</a>). In our center, the posterolateral vein is often used when the branches of the coronary sinus are technically difficult to access, although it is generally difficult to characterize. However, this vein is only used as an alternative, since the distance between it and the RV apex gives insufficient time for myocardial activation. Furthermore, the fact that both leads activating the ventricular mass are relatively close could trigger new dyssynchrony by the late activation of more distant areas of the myocardium.</p><elsevierMultimedia ident="fig0005"></elsevierMultimedia><elsevierMultimedia ident="fig0010"></elsevierMultimedia><p id="par0030" class="elsevierStylePara elsevierViewall">One month after implantation, the patient returned to our department after suffering 12 shocks in 24 hours. Device interrogation revealed these to have been appropriate shocks in response to an arrhythmic storm of multiple episodes of rapid ventricular tachycardia (VT) with a mean cycle length of 250 ms (<a class="elsevierStyleCrossRef" href="#fig0015">Figure 3</a>). At the same time reproducible ventricular bigeminy and VT runs induced by BiV pacing were seen. Various programming modes were tested with different pulse polarities, amplitudes and widths, as well as left ventricular pacing alone, none of which eliminated the ventricular extrasystoles. In view of the failure of these attempts, pacing via the left ventricular lead was switched off and the patient regained natural rhythm without ventricular extrasystoles, with RV pacing set to a minimum of 40 bpm. The CRT-D was programmed with three zones: VT-1, from 171 bpm with two bursts of antitachycardia pacing; VT-2, from 182 bpm, with two ramps followed if necessary by a 40-J shock; and VF, from 200 bpm, with up to six 40-J shocks.</p><elsevierMultimedia ident="fig0015"></elsevierMultimedia><p id="par0035" class="elsevierStylePara elsevierViewall">Holter 24-hour monitoring performed two months later showed natural rhythm (AF) in 99% of the record, with only 195 isolated dimorphic ventricular extrasystoles, one pair and one 4-complex run. The patient was under medication with amiodarone 200 mg/day and carvedilol 6.25 mg twice daily.</p><p id="par0040" class="elsevierStylePara elsevierViewall">Echocardiography five months after switching off LV pacing showed continuing very low EF (13%) with evidence of intra- and interventricular dyssynchrony; the patient remained in NYHA class III.</p><p id="par0045" class="elsevierStylePara elsevierViewall">It was decided to make another attempt to implement CRT. Since no other branch of the coronary sinus could be catheterized, an epicardial lead was implanted in the lateral LV wall (<a class="elsevierStyleCrossRef" href="#fig0020">Figure 4</a>). The alternative of repositioning the RV lead to a septal position was not chosen because, before CRT implantation, the segments with the latest activation were those of the lateral wall, the distance between the leads would not be significantly increased by this change, and in order to begin pacing via the LV lead it would have to be implanted in a less arrhythmogenic position.</p><elsevierMultimedia ident="fig0020"></elsevierMultimedia><p id="par0050" class="elsevierStylePara elsevierViewall">An epicardial lead was implanted between the second and third obtuse marginals by submammary thoracotomy.</p><p id="par0055" class="elsevierStylePara elsevierViewall">One month later, the patient was still in NYHA class III, with poor global systolic function. The LV pacing percentage was 89% and the RV pacing percentage was 13%. The low percentage of BiV pacing is explained by the rapid intrinsic rates resulting from the patient's AF. However, no ventricular arrhythmias were recorded by the device.</p><p id="par0060" class="elsevierStylePara elsevierViewall">Digoxin was added to the patient's therapeutic regime to control her intrinsic ventricular rate, the minimum pacing rate was raised to 80 bpm, and she was enrolled in a cardiac rehabilitation program. We opted for a conservative approach to maximize BiV pacing rate through optimizing medical therapy and reprogramming the device, given the theoretically greater risk of loss of capture by the epicardial lead than if the lead had been positioned in the coronary sinus venous system. If this strategy failed, the next step would be ablation of the atrioventricular node. If the LV lead had been in the coronary venous system, then nodal ablation would have been the first option.</p><p id="par0065" class="elsevierStylePara elsevierViewall">At six months after implantation of the epicardial LV lead and after an increase in the percentage of BiV pacing, the patient was still in NYHA class III, but reported slight symptomatic improvement in her day-to-day activities, and her EF had risen to 19%. No new episodes of decompensated HF occurred and no ventricular arrhythmias were detected by remote monitoring during this period.</p></span><span id="sec0015" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0035">Discussion</span><p id="par0070" class="elsevierStylePara elsevierViewall">Initial reports of the impact of CRT on the incidence of ventricular arrhythmias show an antiarrhythmic effect,<a class="elsevierStyleCrossRefs" href="#bib0045"><span class="elsevierStyleSup">9,10</span></a> which could be due to reduction of wall stress caused by the inverse remodeling induced by BiV pacing, decreased dispersion of ventricular repolarization resulting from dual depolarization wave fronts,<a class="elsevierStyleCrossRefs" href="#bib0055"><span class="elsevierStyleSup">11,12</span></a> and reduced sympathetic nervous system activation.<a class="elsevierStyleCrossRef" href="#bib0065"><span class="elsevierStyleSup">13</span></a></p><p id="par0075" class="elsevierStylePara elsevierViewall">Other studies suggested that this antiarrhythmic effect is due to reductions in the number of ventricular extrasystoles,<a class="elsevierStyleCrossRef" href="#bib0070"><span class="elsevierStyleSup">14</span></a> the incidence of tachyarrhythmic events<a class="elsevierStyleCrossRef" href="#bib0075"><span class="elsevierStyleSup">15</span></a> and the inducibility of sustained VT.<a class="elsevierStyleCrossRef" href="#bib0080"><span class="elsevierStyleSup">16</span></a> More recent research has indicated that this effect is mainly seen in patients who respond to CRT, as a consequence of the hemodynamic improvement induced by BiV pacing,<a class="elsevierStyleCrossRefs" href="#bib0085"><span class="elsevierStyleSup">17,18</span></a> but not in non-responders.</p><p id="par0080" class="elsevierStylePara elsevierViewall">Indications for CRT have widened in the last 10 years and research into its consequences has intensified, but its electrophysiological effects on the incidence of sudden death and ventricular arrhythmias are still poorly understood.</p><p id="par0085" class="elsevierStylePara elsevierViewall">Cases have been reported of increased arrhythmic events in some patients when treated with BiV pacing.<a class="elsevierStyleCrossRefs" href="#bib0095"><span class="elsevierStyleSup">19–21</span></a> In 2005, Shukla et al.<a class="elsevierStyleCrossRef" href="#bib0095"><span class="elsevierStyleSup">19</span></a> described a series of 145 consecutive patients, five of whom developed arrhythmic storm after implantation of a CRT-D, which was permanently resolved by discontinuing LV pacing. Similarly, Medina-Ravell et al.<a class="elsevierStyleCrossRef" href="#bib0100"><span class="elsevierStyleSup">20</span></a> assessed 29 patients who received a CRT-D, four of whom developed ventricular extrasystoles with BiV pacing, eliminated when LV pacing was ended. The same phenomenon is seen in the case presented here.</p><p id="par0090" class="elsevierStylePara elsevierViewall">Further evidence is found in the two largest randomized clinical trials to assess the effects of CRT in patients with and without an implantable defibrillator, which showed a reduction in all-cause mortality compared to OMT (COMPANION<a class="elsevierStyleCrossRef" href="#bib0020"><span class="elsevierStyleSup">4</span></a> and CARE-HF<a class="elsevierStyleCrossRef" href="#bib0025"><span class="elsevierStyleSup">5</span></a>), the percentage of sudden death as a cause of death was slightly higher in those without a defibrillator.<a class="elsevierStyleCrossRef" href="#bib0110"><span class="elsevierStyleSup">22</span></a></p><p id="par0095" class="elsevierStylePara elsevierViewall">In the COMPANION trial, there was a statistically significant reduction of 36% in all-cause death (p=0.003) in patients under OMT and CRT compared to OMT only. However, the incidence of sudden death was higher in those under CRT with pacing only plus OMT than in those with OMT only (7.8% vs. 5.8%), while in those with CRT-D and OMT it was only 2.9%. Analysis of causes of death in the three groups shows that sudden death was responsible in 36.6% of patients with CRT with pacing only plus OMT, 23.4% of those with OMT only, and only 16.2% of those with CRT-D and OMT.<a class="elsevierStyleCrossRef" href="#bib0110"><span class="elsevierStyleSup">22</span></a></p><p id="par0100" class="elsevierStylePara elsevierViewall">In the CARE-HF trial, although mortality was lower in patients undergoing CRT than in those receiving OMT only, the percentage of the former suffering sudden death was higher (35.4% vs. 31.7%).</p><p id="par0105" class="elsevierStylePara elsevierViewall">However, evidence to the contrary recently came from the REVERSE study, which assessed the incidence of VT/ventricular fibrillation and sustained VT in patients with CRT-D devices, one group with BiV pacing on and the other with pacing off. After two years of follow-up, the incidence of arrhythmic events was similar in the two groups (18.7% vs. 21.9%, p=0.84).<a class="elsevierStyleCrossRef" href="#bib0115"><span class="elsevierStyleSup">23</span></a></p><p id="par0110" class="elsevierStylePara elsevierViewall">In the normal sequence of myocardial activation, the endocardium is depolarized before the more epicardial layers, while repolarization travels in the opposite direction (from epicardium to endocardium). BiV pacing is normally effected via an endocardial lead placed in the RV and a lead placed inside the coronary sinus or one of its branches, and so the LV myocardium is stimulated via the epicardium. Epicardial pacing involves a non-physiological activation sequence in which the vector of the transmural propagation is reversed, resulting in delayed endocardial depolarization and earlier epicardial depolarization.<a class="elsevierStyleCrossRef" href="#bib0120"><span class="elsevierStyleSup">24</span></a> Experimental studies have shown that epicardial-endocardial conduction time is significantly longer than endocardial-epicardial conduction time, due to a zone of myocardial wall between the deep subendocardium and mid-myocardial layers.<a class="elsevierStyleCrossRefs" href="#bib0125"><span class="elsevierStyleSup">25,26</span></a> The resulting increased dispersion of repolarization prolongs QT and JT intervals and the interval between the peak and the end of the T wave.<a class="elsevierStyleCrossRefs" href="#bib0125"><span class="elsevierStyleSup">25,27</span></a></p><p id="par0115" class="elsevierStylePara elsevierViewall">Furthermore, a small number of predisposed patients may be more likely to suffer reentrant phenomena. The presence of cardiomyopathy, use of QT-prolonging drugs, and autonomic dysregulation can also promote these phenomena.<a class="elsevierStyleCrossRefs" href="#bib0140"><span class="elsevierStyleSup">28,29</span></a></p><p id="par0120" class="elsevierStylePara elsevierViewall">Identification of factors that predispose to ventricular arrhythmias caused by BiV pacing is thus of considerable clinical importance in the assessment of candidates for this therapy and in the decision whether to implant a CRT-D system.</p><p id="par0125" class="elsevierStylePara elsevierViewall">The predictors of arrhythmias in these patients have not been fully identified. In a study of 75 patients undergoing CRT, variation in QT dispersion before and after implantation was an independent predictor of major arrhythmic events; in a follow-up of 807 days, in the group with increased QT dispersion the incidence of events was 29%, while in those in whom it decreased, the incidence was 3% (p=0.0017).<a class="elsevierStyleCrossRef" href="#bib0150"><span class="elsevierStyleSup">30</span></a></p><p id="par0130" class="elsevierStylePara elsevierViewall">The same study<a class="elsevierStyleCrossRef" href="#bib0150"><span class="elsevierStyleSup">30</span></a> assessed the interval between the peak and the end of the T wave (T<span class="elsevierStyleInf">peak-end</span>), another marker of dispersion of repolarization. Patients who suffered arrhythmic events during follow-up had a significantly smaller reduction in T<span class="elsevierStyleInf">peak-end</span> than those who were event-free (−1.5±12.8 ms vs. −20.0±5.4 ms, p=0.047).</p><p id="par0135" class="elsevierStylePara elsevierViewall">The mechanisms involved in this differing QT dispersion response to CRT have not been investigated. It is thought that factors such as severe systolic dysfunction,<a class="elsevierStyleCrossRef" href="#bib0145"><span class="elsevierStyleSup">29</span></a> perfusion disturbances<a class="elsevierStyleCrossRef" href="#bib0155"><span class="elsevierStyleSup">31</span></a> and stimulation of LV myocardium in areas close to fibrotic tissue<a class="elsevierStyleCrossRef" href="#bib0160"><span class="elsevierStyleSup">32</span></a> could in theory be related to changes in QT dispersion.</p><p id="par0140" class="elsevierStylePara elsevierViewall">Dilated cardiomyopathy is associated with ventricular fibrosis, changes in muscle tissue architecture and abnormalities of cellular ultrastructure, particularly in cell membranes.<a class="elsevierStyleCrossRefs" href="#bib0165"><span class="elsevierStyleSup">33,34</span></a> The electrophysiological properties of cardiomyopathic myocardium are also altered by lines of conduction block resulting from fibrosis and areas of abnormal conductibility and refractoriness.<a class="elsevierStyleCrossRef" href="#bib0175"><span class="elsevierStyleSup">35</span></a> The zones with altered electrophysiological properties are not homogenous throughout the dysfunctional myocardium,<a class="elsevierStyleCrossRef" href="#bib0180"><span class="elsevierStyleSup">36</span></a> and the patterns of their distribution appear to differ between ischemic and non-ischemic dilated cardiomyopathy,<a class="elsevierStyleCrossRef" href="#bib0180"><span class="elsevierStyleSup">36</span></a> with more diffuse involvement, mainly in the basal segments, in the latter compared to the former, in which these zones tend to be restricted to particular arterial territories and typically affect the endocardium more extensively.<a class="elsevierStyleCrossRefs" href="#bib0185"><span class="elsevierStyleSup">37,38</span></a> In the case presented, the patient had severe valvular disease and had undergone mitral valve replacement, which may have altered the tissue architecture and hence the distribution of zones with altered electrophysiological properties.</p><p id="par0145" class="elsevierStylePara elsevierViewall">When a pro-arrhythmic effect of BiV pacing is suspected, an alternative site for LV stimulation can reduce arrhythmogenicity. In our patient, the lack of options led us to adopt a surgical approach, and during thoracotomy threshold tests were performed in different parts of the epicardium and the induction of ventricular extrasystoles by BiV pacing was assessed.</p><p id="par0150" class="elsevierStylePara elsevierViewall">Various strategies have been tried to overcome the potential arrhythmic risk of LV stimulation via branches of the coronary sinus, including endocardial LV pacing with the lead positioned via transseptal puncture. Initial results of this procedure, still in the early stages of evaluation, are promising.<a class="elsevierStyleCrossRefs" href="#bib0195"><span class="elsevierStyleSup">39,40</span></a></p><p id="par0155" class="elsevierStylePara elsevierViewall">Assessment of heterogeneity of repolarization during implantation is considered of little value, since no correlation has been established between changes in these parameters and adverse events, and any pro-arrhythmic effect may only be manifested hours or days after implantation.<a class="elsevierStyleCrossRef" href="#bib0205"><span class="elsevierStyleSup">41</span></a></p></span><span id="sec0020" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0040">Conclusion</span><p id="par0160" class="elsevierStylePara elsevierViewall">CRT is not without adverse effects. Although its benefits clearly outweigh the risks in patients with indication for this therapy, in rare cases BiV pacing may induce arrhythmias. Reversal of the physiological depolarization sequence increases dispersion of repolarization, promoting reentry phenomena and increasing the incidence of ventricular arrhythmias in some patients.</p><p id="par0165" class="elsevierStylePara elsevierViewall">Although the paradoxical increase in arrhythmogenicity with CRT is uncommon, it can have serious clinical consequences that reprogramming alone cannot prevent. In the case presented, only removal of the pacing lead from the coronary sinus eliminated the ventricular arrhythmia. Since ventricular resynchronization was necessary, an alternative site for the LV pacing lead had to be found, and an epicardial approach was the one chosen.</p></span><span id="sec0025" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0045">Ethical disclosures</span><span id="sec0030" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0050">Protection of human and animal subjects</span><p id="par0170" class="elsevierStylePara elsevierViewall">The authors declare that no experiments were performed on humans or animals for this study.</p></span><span id="sec0035" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0055">Confidentiality of data</span><p id="par0175" class="elsevierStylePara elsevierViewall">The authors declare that they have followed the protocols of their work center on the publication of patient data.</p></span><span id="sec0040" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0060">Right to privacy and informed consent</span><p id="par0180" class="elsevierStylePara elsevierViewall">The authors have obtained the written informed consent of the patients or subjects mentioned in the article. The corresponding author is in possession of this document.</p></span></span><span id="sec0045" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0065">Conflicts of interest</span><p id="par0185" class="elsevierStylePara elsevierViewall">The authors have no conflicts of interest to declare.</p></span></span>" "textoCompletoSecciones" => array:1 [ "secciones" => array:11 [ 0 => array:2 [ "identificador" => "xres350682" "titulo" => "Abstract" ] 1 => array:2 [ "identificador" => "xpalclavsec332238" "titulo" => "Keywords" ] 2 => array:2 [ "identificador" => "xres350681" "titulo" => "Resumo" ] 3 => array:2 [ "identificador" => "xpalclavsec332239" "titulo" => "Palavras-chave" ] 4 => array:2 [ "identificador" => "sec0005" "titulo" => "Introduction" ] 5 => array:2 [ "identificador" => "sec0010" "titulo" => "Case report" ] 6 => array:2 [ "identificador" => "sec0015" "titulo" => "Discussion" ] 7 => array:2 [ "identificador" => "sec0020" "titulo" => "Conclusion" ] 8 => array:3 [ "identificador" => "sec0025" "titulo" => "Ethical disclosures" "secciones" => array:3 [ 0 => array:2 [ "identificador" => "sec0030" "titulo" => "Protection of human and animal subjects" ] 1 => array:2 [ "identificador" => "sec0035" "titulo" => "Confidentiality of data" ] 2 => array:2 [ "identificador" => "sec0040" "titulo" => "Right to privacy and informed consent" ] ] ] 9 => array:2 [ "identificador" => "sec0045" "titulo" => "Conflicts of interest" ] 10 => array:1 [ "titulo" => "References" ] ] ] "pdfFichero" => "main.pdf" "tienePdf" => true "fechaRecibido" => "2012-12-14" "fechaAceptado" => "2014-01-20" "PalabrasClave" => array:2 [ "en" => array:1 [ 0 => array:4 [ "clase" => "keyword" "titulo" => "Keywords" "identificador" => "xpalclavsec332238" "palabras" => array:3 [ 0 => "Cardiac resynchronization" 1 => "Epicardial pacing" 2 => "Repolarization heterogeneity" ] ] ] "pt" => array:1 [ 0 => array:4 [ "clase" => "keyword" "titulo" => "Palavras-chave" "identificador" => "xpalclavsec332239" "palabras" => array:3 [ 0 => "Ressincronização cardíaca" 1 => "<span class="elsevierStyleItalic">Pacing</span> epicárdico" 2 => "Heterogeneidade da repolarização" ] ] ] ] "tieneResumen" => true "resumen" => array:2 [ "en" => array:2 [ "titulo" => "Abstract" "resumen" => "<p id="spar0005" class="elsevierStyleSimplePara elsevierViewall">The demonstrated benefits of cardiac resynchronization therapy (CRT) in reducing mortality and hospitalizations for heart failure, improving NYHA functional class and inducing reverse remodeling have led to its increasing use in clinical practice. However, its potential contribution to complex ventricular arrhythmias is controversial.</p><p id="spar0010" class="elsevierStyleSimplePara elsevierViewall">We present the case of a female patient with valvular heart failure and severe systolic dysfunction, in NYHA class III and under optimal medical therapy, without previous documented ventricular arrhythmias. After implantation of a CRT defibrillator, she suffered an arrhythmic storm with multiple episodes of monomorphic ventricular tachycardia (VT), requiring 12 shocks. Subsequently, a pattern of ventricular bigeminy was observed, as well as reproducible VT runs induced by biventricular pacing.</p><p id="spar0015" class="elsevierStyleSimplePara elsevierViewall">Since no other vein of the coronary sinus system was accessible, it was decided to implant an epicardial lead to stimulate the left ventricle, positioned in the left ventricular mid-lateral wall. No arrhythmias were detected in the following six months.</p><p id="spar0020" class="elsevierStyleSimplePara elsevierViewall">This case highlights the possible proarrhythmic effect of biventricular pacing with a left ventricular lead positioned in the coronary sinus venous system.</p>" ] "pt" => array:2 [ "titulo" => "Resumo" "resumen" => "<p id="spar0025" class="elsevierStyleSimplePara elsevierViewall">Os benefícios demonstrados com a terapêutica de ressincronização cardíaca (TRC) na redução da mortalidade e hospitalização por ICC, melhoria da classe funcional e obtenção de remodelagem inversa em doentes selecionados com insuficiência cardíaca (ICC), têm contribuído para a crescente utilização destes dispositivos na prática clínica.</p><p id="spar0030" class="elsevierStyleSimplePara elsevierViewall">No entanto, permanece controverso o impacto da TRC como fator causador de arritmias ventriculares complexas. Apresentamos o caso duma doente com cardiopatia valvular operada, disfunção sistólica grave e ICC classe III da NYHA, com terapêutica médica otimizada, sem documentação prévia de arritmias ventriculares significativas. Após implantação do sistema de TRC com cardioversor-desfibrilhador, desenvolveu quadro de tempestade arrítmica com múltiplos episódios de taquicardia ventricular monomórfica (TV) e necessidade de 12 choques, mantendo padrão de bigeminismo ventricular reprodutível e indução de salvas de TV pelo <span class="elsevierStyleItalic">pacing</span> biventricular. Dada a inacessibilidade a outra veia tributária do seio coronário foi decidido implantar elétrodo epicárdico em localização diferente (de veia póstero-lateral para posição lateral-mediana), sem registo de recorrência de arritmias num <span class="elsevierStyleItalic">follow-up</span> de seis meses. Este caso sugere que a TRC pode contribuir para um efeito pró-arrítmico com consequências clínicas potencialmente graves.</p>" ] ] "NotaPie" => array:1 [ 0 => array:2 [ "etiqueta" => "☆" "nota" => "<p class="elsevierStyleNotepara" id="npar0005">Please cite this article as: Cabanelas N, Oliveira M, Nogueira da Silva M, et al. Terapêutica de ressincronização cardíaca e efeito pró-arrítmico: um problema que deve ser lembrado. Rev Port Cardiol. 2014;33:309.e1–309.e7.</p>" ] ] "multimedia" => array:4 [ 0 => array:7 [ "identificador" => "fig0005" "etiqueta" => "Figure 1" "tipo" => "MULTIMEDIAFIGURA" "mostrarFloat" => true "mostrarDisplay" => false "figura" => array:1 [ 0 => array:4 [ "imagen" => "gr1.jpeg" "Alto" => 1482 "Ancho" => 1495 "Tamanyo" => 118448 ] ] "descripcion" => array:1 [ "en" => "<p id="spar0035" class="elsevierStyleSimplePara elsevierViewall">Angiogram of the coronary sinus, showing sparse venous system.</p>" ] ] 1 => array:7 [ "identificador" => "fig0010" "etiqueta" => "Figure 2" "tipo" => "MULTIMEDIAFIGURA" "mostrarFloat" => true "mostrarDisplay" => false "figura" => array:1 [ 0 => array:4 [ "imagen" => "gr2.jpeg" "Alto" => 1495 "Ancho" => 1500 "Tamanyo" => 114831 ] ] "descripcion" => array:1 [ "en" => "<p id="spar0040" class="elsevierStyleSimplePara elsevierViewall">Angiogram of the posterior vein.</p>" ] ] 2 => array:7 [ "identificador" => "fig0015" "etiqueta" => "Figure 3" "tipo" => "MULTIMEDIAFIGURA" "mostrarFloat" => true "mostrarDisplay" => false "figura" => array:1 [ 0 => array:4 [ "imagen" => "gr3.jpeg" "Alto" => 1750 "Ancho" => 3181 "Tamanyo" => 466109 ] ] "descripcion" => array:1 [ "en" => "<p id="spar0045" class="elsevierStyleSimplePara elsevierViewall">Onset of episode of ventricular tachycardia recorded by the Home Monitoring system (Biotronik<span class="elsevierStyleSup">®</span>).</p>" ] ] 3 => array:7 [ "identificador" => "fig0020" "etiqueta" => "Figure 4" "tipo" => "MULTIMEDIAFIGURA" "mostrarFloat" => true "mostrarDisplay" => false "figura" => array:1 [ 0 => array:4 [ "imagen" => "gr4.jpeg" "Alto" => 1735 "Ancho" => 1667 "Tamanyo" => 94234 ] ] "descripcion" => array:1 [ "en" => "<p id="spar0050" class="elsevierStyleSimplePara elsevierViewall">Chest X-ray, anteroposterior view, showing pacing lead in the posterior vein (blue arrow) and epicardial lead in lateral position (red arrow).</p>" ] ] ] "bibliografia" => array:2 [ "titulo" => "References" "seccion" => array:1 [ 0 => array:2 [ "identificador" => "bibs0005" "bibliografiaReferencia" => array:41 [ 0 => array:3 [ "identificador" => "bib0005" "etiqueta" => "1" "referencia" => array:1 [ 0 => array:2 [ "contribucion" => array:1 [ 0 => array:2 [ "titulo" => "Long-term benefits of biventricular pacing in congestive heart failure: results from the MUltisite STimulation in cardiomyopathy (MUSTIC) study" "autores" => array:1 [ 0 => array:2 [ "etal" => true "autores" => array:3 [ 0 => "C. 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| Year/Month | Html | Total | |
|---|---|---|---|
| 2024 November | 13 | 7 | 20 |
| 2024 October | 52 | 37 | 89 |
| 2024 September | 48 | 23 | 71 |
| 2024 August | 46 | 25 | 71 |
| 2024 July | 33 | 28 | 61 |
| 2024 June | 36 | 38 | 74 |
| 2024 May | 41 | 27 | 68 |
| 2024 April | 26 | 25 | 51 |
| 2024 March | 30 | 15 | 45 |
| 2024 February | 37 | 35 | 72 |
| 2024 January | 24 | 33 | 57 |
| 2023 December | 27 | 29 | 56 |
| 2023 November | 30 | 21 | 51 |
| 2023 October | 23 | 18 | 41 |
| 2023 September | 21 | 15 | 36 |
| 2023 August | 37 | 19 | 56 |
| 2023 July | 33 | 16 | 49 |
| 2023 June | 20 | 10 | 30 |
| 2023 May | 44 | 25 | 69 |
| 2023 April | 40 | 8 | 48 |
| 2023 March | 35 | 18 | 53 |
| 2023 February | 33 | 26 | 59 |
| 2023 January | 35 | 19 | 54 |
| 2022 December | 42 | 22 | 64 |
| 2022 November | 64 | 26 | 90 |
| 2022 October | 48 | 17 | 65 |
| 2022 September | 70 | 26 | 96 |
| 2022 August | 82 | 29 | 111 |
| 2022 July | 101 | 28 | 129 |
| 2022 June | 46 | 22 | 68 |
| 2022 May | 39 | 26 | 65 |
| 2022 April | 56 | 23 | 79 |
| 2022 March | 51 | 25 | 76 |
| 2022 February | 36 | 21 | 57 |
| 2022 January | 22 | 28 | 50 |
| 2021 December | 21 | 30 | 51 |
| 2021 November | 36 | 39 | 75 |
| 2021 October | 33 | 34 | 67 |
| 2021 September | 35 | 24 | 59 |
| 2021 August | 40 | 37 | 77 |
| 2021 July | 16 | 26 | 42 |
| 2021 June | 21 | 27 | 48 |
| 2021 May | 30 | 43 | 73 |
| 2021 April | 31 | 22 | 53 |
| 2021 March | 45 | 22 | 67 |
| 2021 February | 62 | 10 | 72 |
| 2021 January | 25 | 13 | 38 |
| 2020 December | 43 | 8 | 51 |
| 2020 November | 58 | 25 | 83 |
| 2020 October | 47 | 10 | 57 |
| 2020 September | 68 | 5 | 73 |
| 2020 August | 22 | 7 | 29 |
| 2020 July | 72 | 5 | 77 |
| 2020 June | 34 | 2 | 36 |
| 2020 May | 41 | 5 | 46 |
| 2020 April | 46 | 5 | 51 |
| 2020 March | 39 | 9 | 48 |
| 2020 February | 102 | 41 | 143 |
| 2020 January | 48 | 10 | 58 |
| 2019 December | 33 | 7 | 40 |
| 2019 November | 49 | 8 | 57 |
| 2019 October | 43 | 3 | 46 |
| 2019 September | 19 | 11 | 30 |
| 2019 August | 27 | 3 | 30 |
| 2019 July | 36 | 11 | 47 |
| 2019 June | 38 | 9 | 47 |
| 2019 May | 39 | 10 | 49 |
| 2019 April | 26 | 15 | 41 |
| 2019 March | 29 | 10 | 39 |
| 2019 February | 72 | 6 | 78 |
| 2019 January | 58 | 9 | 67 |
| 2018 December | 83 | 11 | 94 |
| 2018 November | 133 | 5 | 138 |
| 2018 October | 367 | 14 | 381 |
| 2018 September | 109 | 22 | 131 |
| 2018 August | 82 | 16 | 98 |
| 2018 July | 78 | 5 | 83 |
| 2018 June | 93 | 4 | 97 |
| 2018 May | 109 | 5 | 114 |
| 2018 April | 113 | 10 | 123 |
| 2018 March | 79 | 6 | 85 |
| 2018 February | 66 | 6 | 72 |
| 2018 January | 105 | 6 | 111 |
| 2017 December | 216 | 6 | 222 |
| 2017 November | 59 | 12 | 71 |
| 2017 October | 48 | 11 | 59 |
| 2017 September | 29 | 11 | 40 |
| 2017 August | 49 | 11 | 60 |
| 2017 July | 34 | 13 | 47 |
| 2017 June | 58 | 7 | 65 |
| 2017 May | 64 | 13 | 77 |
| 2017 April | 49 | 1 | 50 |
| 2017 March | 47 | 20 | 67 |
| 2017 February | 43 | 7 | 50 |
| 2017 January | 42 | 3 | 45 |
| 2016 December | 40 | 12 | 52 |
| 2016 November | 32 | 8 | 40 |
| 2016 October | 34 | 7 | 41 |
| 2016 September | 32 | 9 | 41 |
| 2016 August | 8 | 2 | 10 |
| 2016 July | 20 | 11 | 31 |
| 2016 June | 10 | 6 | 16 |
| 2016 May | 10 | 9 | 19 |
| 2016 April | 40 | 1 | 41 |
| 2016 March | 70 | 10 | 80 |
| 2016 February | 74 | 25 | 99 |
| 2016 January | 57 | 17 | 74 |
| 2015 December | 68 | 12 | 80 |
| 2015 November | 63 | 9 | 72 |
| 2015 October | 63 | 11 | 74 |
| 2015 September | 68 | 18 | 86 |
| 2015 August | 59 | 16 | 75 |
| 2015 July | 46 | 10 | 56 |
| 2015 June | 29 | 6 | 35 |
| 2015 May | 38 | 11 | 49 |
| 2015 April | 41 | 7 | 48 |
| 2015 March | 31 | 6 | 37 |
| 2015 February | 38 | 10 | 48 |
| 2015 January | 35 | 10 | 45 |
| 2014 December | 57 | 17 | 74 |
| 2014 November | 50 | 15 | 65 |
| 2014 October | 50 | 16 | 66 |
| 2014 September | 61 | 16 | 77 |
| 2014 August | 57 | 20 | 77 |
| 2014 July | 82 | 38 | 120 |
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