Narrow QRS Research Articles

The jugular approach for leadless pacing: A novel and safe alternative.

To evaluate safety of leadless pacemaker implantation through the internal jugular vein in a larger cohort with longer follow-up. Moreover, feasibility of non-apical pacing as well as relation between pacing site and QRS duration were assessed. Eighty Two consecutive patients, who received a leadless pacemaker though the internal jugular vein, were included. Electrical parameters were measured at regular follow-up and any complications were registered. Paced QRS interval was compared for three pacing sites, RVOT, RV mid septum, and RV apical septum. In all patients, the leadless pacemaker was implanted successfully. In 69 patients, the device was implanted in a non-apical position. In 71% of cases, the device could be deployed at first attempt. The median fluoroscopy time was 4.4 min (range 0.9-51) The paced QRS interval was significantly narrower for non-apical pacing sites compared to apical pacing si 156 vs. 179ms. p=.04, respectively. During mean follow-up of 16 months (range 0-43 months), electrical parameters remained stable. Two complications occurred, which could be resolved during the implant procedure. There were no access site related complications. The jugular approach for leadless pacemaker implantation is feasible and may avoid vascular complications. It facilitates non-apical positioning of leadless pacemakers leading to a narrower paced QRS interval. The jugular approach allows for immediate post procedural ambulation.

Left bundle branch area pacing in patients with atrioventricular conduction disease: A prospective multicenter study

The reported success rate of His-bundle pacing (HBP) in patients with infranodal atrioventricular (AV) conduction disease is only 52%-76%. The success rate of left bundle branch area pacing (LBBAP) in this cohort is not well studied. The purpose of this study was to evaluate the feasibility, safety, and electrophysiological characteristics of LBBAP in patients with AV conduction disease. Patients with AV conduction disease referred for pacemaker implantation at 2 centers between February 2019 and June 2021 were considered for LBBAP. Baseline demographic characteristics, procedural success rates, electrophysiological parameters, and complications were assessed. LBBAP was successful in 340 of 364 patients (93%). Mean age was 72 ± 13 years, and mean follow-up was 331 ± 244 days. Pacing indications were Mobitz I in 27 patients (7%), Mobitz II or 2:1 AV block or high-grade AV block in 94 patients (26%), complete heart block in 199 patients (55%), and sick sinus syndrome with isolated bundle branch block in 44 patients (12%). Left bundle branch block and right bundle branch block were present in 57 patients (16%) and 140 patients (38%), respectively. Procedural success rates did not differ between indications (92.6%, 93.6%, 92.9%, and 95%, respectively) or between patients with narrow (<120 ms) vs wide QRS (≥120 ms). Mean LBBAP threshold was 0.77 ± 0.34 V at 0.4 ms at implant and remained stable during follow-up. There were 4 (1.2%) acute LBBAP lead dislodgments. LBBAP is safe and feasible with high success rates for patients with AV conduction disease. In contrast to HBP, LBBAP success rates remain high over the entire spectrum of AV conduction disease, and lead parameters remain stable during follow-up.

A narrow QRS complex tachycardia: What is the mechanism?

A 45-year-old man complained of recurrent episodes of palpitations. Twelve-lead electrocardiograms revealed a long RP and regular narrow QRS complex tachycardia. The baseline atrio-His and His-ventricular intervals were 130 and 55 ms, respectively. A narrow QRS complex tachycardia with a cycle length of 407 ms was reproducibly induced by a single atrial or ventricular extrastimulus. During the tachycardia, the atrial activation sequence with earliest activation in the proximal coronary sinus was identical to the retrograde atrial activation sequence during right ventricular pacing.

Interaction of sex and diabetes in Asian patients with heart failure with mildly reduced left ventricular ejection fraction

The impact of sex and diabetes mellitus (DM) on patients with heart failure with mildly reduced ejection fraction (HFmrEF) is not well elucidated. This study aims to evaluate sex differences in the clinical profile and outcomes in Asian HFmrEF patients with and without DM. Patients admitted nationally for HFmrEF (ejection fraction 40-49%) between 2008 and 2014 were included and followed up until December 2016. The primary outcome was all-cause mortality. Secondary outcomes included cardiovascular (CV) death and/or heart failure (HF) rehospitalisations. A total of 2,272 HFmrEF patients (56% male) were included. More women had DM than men (60% versus 55%, P=0.013). Regardless of DM status, HFmrEF females were older, less likely to smoke, had less coronary artery disease, narrower QRS and lower haemoglobin compared to men. The odds of having DM decreases in smokers who are women as opposed to men (Pinteraction =0.017). In multivariate analysis, DM reached statistical analysis for all-cause mortality and combined CV mortality or HF rehospitalisation in both men and women. However, the results suggest that there may be sex differences in terms of outcomes. DM (vs non-DM) was less strongly associated with increased all-cause mortality (adjusted hazards ratio [adj HR] 1.234 vs adj HR 1.290, Pinteraction <0.001] but more strongly associated with the combined CV death/HF rehospitalisation (adj HR 1.429 vs adj HR 1.317, Pinteraction =0.027) in women (vs men). Asian women with HFmrEF had a higher prevalence of DM, with differences in clinical characteristics, compared to men. While diabetes conferred poor outcomes regardless of sex, there were distinct sex differences. These highlight the need for sex-specific management strategies.

Right ventricular lead sensing latency in pacemaker therapy.

BackgroundPacemaker implantation involves intraoperative testing of ventricular sensing using a device called a pacing system analyzer (PSA). The value obtained is expected to correspond to those taken by the pacemaker after its implantation. This study determined the latency period for sensing intracardiac electrogram (EGM) by the right ventricular (RV) lead.MethodsPatients without significant heart disease and underlying intrinsic atrioventricular (AV) conduction underwent Medtronic or Abbott dual‐chamber pacemaker implantation with the RV lead positioned on the mid‐septum. Real‐time sensing data were obtained through PSA and after pacemaker implantation to evaluate latency as the time interval Q‐VS between the onset of QRS on surface electrocardiogram and the sensed EGM by the RV lead.ResultsOf 157 patients, 105 had narrow QRS (<120 ms) and 52 had wide QRS of complete right bundle branch block (RBBB). Both narrow‐QRS and RBBB patients had longer sensing latency through PSA (50.9 ± 24.2 and 67.8 ± 32.9 ms, respectively) than through pacemaker (18.2 ± 12.8 and 31.2 ± 14.8 ms, respectively, both p < 0.001). RBBB patients had longer sensing latency compared with narrow QRS patients, either through PSA or through pacemaker (p < 0.001). The sensing latency of Medtronic recipients was longer than those of Abbott in narrow‐QRS (p < 0.05), but not in RBBB.ConclusionWe demonstrated longer RV lead sensing latency (1) through PSA than through pacemaker, (2) in RBBB than in narrow‐QRS, and (3) in Medtronic pacemakers compared with Abbott pacemakers. Knowledge of sensing latency helps the optimization of the AV delay.

Impact of atrioventricular junction ablation and CRT‐D on long‐term mortality in patients with left ventricular dysfunction, permanent, refractory atrial fibrillation, and narrow QRS: Results of a propensity‐matched analysis

In patients with symptomatic permanent atrial fibrillation (PEAF) and narrow QRS, atrio-ventricular junction ablation (AVJA) plus cardiac resynchronization therapy (CRT) is superior to medical therapy in reducing heart failure (HF) hospitalization and all-cause mortality. To compare the mortality of a population of patients with HF, reduced EF (rEF), and PEAF treated with AVJA plus CRT with that of a contemporary cohort of patients in sinus rhythm (SR) with similar baseline characteristics. In this prospective, multicentre, observational study, all-cause mortality in a group of consecutive patients undergoing AVJA and implantable cardioverter-defibrillator (ICD) combined with CRT implantation for HFrEF, narrow QRS, and PEAF with uncontrolled ventricular rate was compared with that of a contemporary cohort of patients in SR undergoing ICD implantation (not combined with CRT) for HFrEF and narrow QRS. Individual 1:1 propensity matching of baseline characteristics was performed. A total of 824 patients were enrolled. Propensity matching yielded 107 matched pairs. After a median follow-up of 52 months, all-cause mortality was similar in patients treated with AVJA plus CRT and in the control group (p = .434). In AVJA plus CRT patients, mortality was significantly lower than in control group patients with a history of paroxysmal/persistent AF (n = 45, p = .020), and similar to that of patients without a history of AF (n = 62, p = .459). After adjustment for patient characteristics, the long-term prognosis of patients with HFrEF, narrow QRS, and PEAF who underwent AVJA plus CRT was similar to that of a population of patients in SR with similar characteristics.

A narrow QRS tachycardia with an atrial sequence not identical to that during ventricular pacing: What is the mechanism?

A 53-year-old man was referred to our hospital because of symptomatic palpitations This article is protected by copyright. All rights reserved.

Successful ablation of a wide complex tachycardia with distinct intracardiac electrograms.

A 13-year-old boy was hospitalized after a syncopal episode that occurred during exercise. He suddenly felt chest tightness, sweating and palpitations, followed by a transient loss of consciousness. Upon emergency medical team arrival, he was awake and oriented. Baseline ECG showed sinus rhythm at a rate of 98 bpm, with narrow QRS, and no signs of long QT, Brugada, or pre-excitation. Physical examination, blood tests, 24 hours Holter monitoring, transthoracic echocardiography and stress test were all within normal limits. Eight days later he experienced a second episode of palpitations while walking to school. ECG revealed regular wide complex tachycardia (WCT) at a rate of 200 bpm, with LBBB morphology that terminated with Adenosine (Figure 1). The clinical tachycardia was easily induced by programmed electrical stimulation (Figure 2A). Diagnostic electrophysiological maneuver (Figure 2B) was followed by successful ablation, during which a unique phenomenon was noted (Figure 3). What is the diagnosis of the tachycardia and what are the unique findings noted during and after ablation? This article is protected by copyright. All rights reserved.

Effects of renal denervation therapy on cardiac function and malignant arrhythmia in patients with reduced left ventricular ejection fraction and narrow QRS complexes treated with implantable cardioverter defibrillator.

Objective : The purpose of this study was to explore the effects of renal denervation (RDN) on cardiac function and malignant arrhythmia in patients with reduced left ventricular ejection fraction (HFrEF) and narrow QRS treated with an implantable cardioverter defibrillator (ICD). Methods: A total of 20 eligible HFrEF patients [left ventricular ejection fraction (LVEF) <40%] and narrow QRS complexes (QRS duration <120 ms) were randomized into either the ICD plus RDN group or the ICD only group during 17 April 2014 to 22 November 2016. Clinical data, including clinical characteristics, blood biochemistry, B-type natriuretic peptide, echocardiographic indexes, 6-min walk distance (6MWD), New York Heart Association (NYHA) classification, and count of ICD discharge events before and after the operation were analyzed. Patients were followed up for up to 3 years post ICD or ICD plus RDN. Results: Baseline clinical data were comparable between the two groups. Higher LVEF (%) (mixed model repeated measure, p = 0.0306) (39.50% ± 9.63% vs. 31.20% ± 4.52% at 1 year; 41.57% ± 9.62% vs. 31.40% ± 8.14% at 3 years), systolic blood pressure (p = 0.0356), and longer 6MWD (p < 0.0001) as well as reduction of NYHA classification (p < 0.0001) were evidenced in the ICD plus RDN group compared to ICD only group during follow-up. Patients in the ICD plus RDN group experienced fewer ICD discharge events (2 vs. 40) and decreased diuretic use; rehospitalization rate (30% vs. 100%, p = 0.0031) and cardiogenic mortality rate (0% vs. 50%, p = 0.0325) were also significantly lower in the ICD plus RDN group than in the ICD only group during follow-up. Conclusion: ICD implantation plus RDN could significantly improve cardiac function and cardiac outcome as well as increase exercise capacity compared to ICD only for HFrEF patients with narrow QRS complexes.

The initial experience of left bundle branch area pacing in patients with hypertrophic cardiomyopathy.

Whether left bundle branch area pacing (LBBAP) could be achieved in patients with hypertrophic cardiomyopathy (HCM) requiring ventricular pacing remains unknown. The present study aimed to investigate the feasibility and effect of LBBAP in HCM. Patients with HCM who underwent LBBAP were recruited from November 2018 to September 2021. Clinical characteristics, echocardiographic, and pacing parameters were prospectively collected at baseline and during follow-up. Eleven consecutive HCM patients who attempted LBBAP were included (mean age 64.0±8.7 years, female 45.5%, mean interventricular septum 16.7mm). The success rate of LBBAP was 36.4% (4/11) and the reason for failed LBBAP in other seven HCM patients was the inability to screw the lead into the deep septum or capture the left bundle branch. Patients with successful LBBAP had significantly narrower QRS duration than those with failed cases (118.0±3.7ms vs. 140.9±9.4ms, p=.01) while the capture thresholds, sensing amplitudes, and pacing impedances were similar. Successful cases presented with less positive late gadolinium enhancement (25.0%vs. 71.4%, p=.02) and thinner interventricular septum thickness (14.5±1.0mm vs. 18.0±2.5mm, p=.02) compared with failed cases. Pacing parameters remained stable and no procedure-related complications occurred during a mean follow-up of 8.9± 7.3 months. LBBAP may be successfully achieved in less than half of HCM patients due to thick interventricular septum and heavy burden of myocardial fibrosis. Pacing strategies should be cautiously considered in patients with HCM.

Unusual response to a ventricular extrastimulus during a narrow QRS tachycardia: What is the mechanism?

Unusual response to a ventricular extrastimulus during a narrow QRS tachycardia: What is the mechanism?

Left bundle branch pacing as an alternative to biventricular pacing for cardiac resynchronisation therapy.

Left bundle branch pacing (LBBP) is anovel physiological pacing technique which may serve as an alternative to biventricular pacing (BVP) for the delivery of cardiac resynchronisation therapy (CRT). This study assessed the feasibility and outcomes of LBBP in comparison to BVP. LBBP was attempted in 40consecutive patients as the first-line method for delivering CRT. To evaluate LBBP versus BVP, 40patients with identical inclusion criteria who received BVP were compared with the LBBP group. Acute success rate, complications, functional and echocardiographic outcomes as well as hospitalisation for heart failure and all-cause mortality 6months after implantation were evaluated. LBBP was successfully performed in 31 (78%) patients and resulted in significant QRS narrowing (from 166 ± 16 to 123 ± 18 ms, p < 0.001), improvement in left ventricular ejection fraction (LVEF; from 28 ± 8 to 43 ± 12%, p < 0.001) and New York Heart Association functional class (from 2.8 ± 0.5 to 1.6 ± 0.6, p < 0.001) at 6months. No LBBP-related complications occurred. Compared to BVP, LBBP resulted in agreater reduction in QRS duration (44 ± 17 vs 15 ± 26 ms, p < 0.001) with comparable absolute improvement in LVEF (15.2 ± 11.7 vs 9.6 ± 12.1%, p = 0.088). Hospitalisation for heart failure and all-cause mortality were similar in the two groups. LBBP is feasible and was safe in 78% of patients with favourable electrical resynchronisation and functional improvement and may serve as an alternative to BVP.

Effectiveness investigation on left bundle branch area pacing in 10 infants and toddlers

Objective: To explore the feasibility, safety and effectiveness of left bundle branch area pacing (LBBAP) in children aged ≤3 years. Methods: A total of 10 children aged ≤3 years who were diagnosed with brady arrhythmia in the First Hospital of Tsinghua University from September 2020 to September 2021 were retrospectively analyzed. All the children met the indication of permanent pacemaker implantation and underwent LBBAP successfully. The intraoperative data (pacing parameters, electrocardiogram and radiographic imaging), cardiac ultrasound data and clinical data during regular postoperative follow-up were recorded. The preoperative and postoperative data were compared using matched samples t test. Results: Ten children (aged (1.6±0.7) years with weight of (10.3±2.5) kg) underwent LBBAP successfully. The QRS wave duration on the postoperative electrocardiogram was (100±9) ms, and the percentage of ventricular pacing was (97±7)%. The postoperative follow-up period was 6 (6, 12) months. At 1 week after operation, the left ventricular end-diastolic diameter Z scores in these children reduced significantly compared with those before operation (1.3±0.6 vs. 3.6±1.1, t=9.37, P<0.001). During the follow-up period, cardiac function was normal and the last left ventricular ejection fraction was (66±4)% in all children. At the last follow-up, the pacing threshold of the 10 children was smaller than 1.0 V and was acceptable. Compared with the intraoperative baseline values, the pacing threshold was slightly higher ((0.8±0.1) vs. (0.5±0.1) V, t=-5.27, P=0.001). However, no significant difference was found regarding sensing threshold ((16±5) vs. (14±4) mV, t=-0.83, P=0.426) and impedance ((584±88) vs. (652±86) Ω, t=2.26, P=0.050). During follow-up, no electrode related complications were recorded. Conclusions: LBBAP is safe and effective for infants and toddlers. Narrow QRS pacing with stable pacing parameters and normal cardiac function could be achieved postoperatively.

His-bundle pacing vs biventricular pacing following atrioventricular nodal ablation in patients with atrial fibrillation and reduced ejection fraction: A multicenter, randomized, crossover study—The ALTERNATIVE-AF trial

Atrioventricular nodal ablation (AVNA) combined with biventricular pacing (BVP) improves outcomes in patients with persistent atrial fibrillation (AF), adequate rate control, and reduced left ventricular ejection fraction (LVEF). His-bundle pacing (HBP) delivers physiological ventricular activation and is a promising alternative to BVP. The purpose of this trial was to compare HBP with BVP following AVNA. In this multicenter, prospective, randomized crossover trial, we recruited patients with persistent AF and reduced LVEF (≤40%). All patients underwent AVNA and received both HBP and BVP. Patients were randomized to either HBP or BVP for 9 months (phase 1), then were switched to the alternative pacing modality for the next 9 months (phase 2). The primary endpoint was change in LVEF. Fifty patients (age 64.3 ± 10.3 years; ventricular rate 93.1 ± 19.9 bpm; 72% male) were enrolled. Thirty-eight patients completed the 2 phases and were included in the crossover analysis. A significant improvement in LVEF was observed with HBP compared to BVP (phase 1: ΔLVEFHBP 21.3% and ΔLVEFBVP 16.7%; phase 2: ΔLVEFHBP 3.5% and ΔLVEFBVP -2.4%; Pgeneralizedadditivemodel = 0.015). Significant improvements in left ventricular end-diastolic diameter, New York Heart Association functional class, and B-type natriuretic peptide level were observed with both pacing modalities compared with baseline, whereas no significant differences were observed between HBP and BVP. HBP delivers a modest but significant improvement in LVEF in patients with persistent AF, impaired ventricular function, and narrow QRS duration post-AVNA compared with BVP. Larger long-term trials are required to confirm the additional improvements in function with HBP.

Implications of QRS Prolongation in Patients With Atrial Fibrillation (from a Multicenter Outpatient Registry)

Patients with atrial fibrillation (AF) at the highest risk of progression to heart failure (HF) need to be identified. We investigated whether QRS duration can stratify patients with AF at risk for poor clinical outcomes, including health-related quality of life (HR-QoL). We analyzed data from a multicenter registry-based cohort study of patients with AF. Patients were grouped according to the QRS duration (narrow: &lt;120 ms; wide: ≥120 ms) at registration (baseline). The primary outcome was a composite of all-cause death and HF hospitalizations during a 2-year follow-up. In addition, the AF effect on the quality-of-life overall summary score was compared between the groups. In 3,269 patients, 302 (9.2%) had a wide QRS; these patients were more likely to be older, male, and have higher CHA₂DS₂-VASc scores than those with a narrow QRS. The incidence of the composite outcome was higher in patients with a wide QRS than those with a narrow QRS (13.1% vs 4.9%, p &lt;0.001). After adjustment, a wide QRS was an independent predictor of the primary outcome (adjusted hazard ratio 1.58, 95% confidence interval 1.09 to 2.29, p=0.016), and the results persisted after the exclusion of patients with bundle branch block or cardiac implantable electronic devices. Regarding HR-QoL outcomes, patients with a wide QRS were less likely to improve AF effect on quality-of-life overall summary scores at 1 year than those with a narrow QRS (adjusted difference -2.31, 95% confidence interval -4.06 to -0.57, p=0.009). QRS prolongation, even for a nonspecific conduction disturbance, was an independent predictor of adverse outcomes and worse HR-QoL in patients with AF.

Supraventricular tachycardias: the underlying mechanisms and the choice of treatment options

The lecture is devoted to one of the most pressing problems of cardiology – the paroxysmal heart rhythm disorders in clinical practice. Supraventricular tachycardias (SVTs) is a common group of cardiac arrhythmias that requires a diagnostic search to establish the mechanisms of formation and selection of optimal treatment tactics. The basic principles of determination of SVTs and their electrophysiological mechanisms are reviewed. The clinical picture and ECG diagnostics of certain forms of tachycardia are outlined. The causes of wide QRS complex tachycardias, and electrocardiographic criteria for the differential diagnosis between ventricular and supraventricular tachycardias with conduction aberration are presented. The key aspects of the diagnosis of wide QRS complex tachycardias are discussed. The emergency care and long-term therapy for SVTs with narrow and wide QRS complexes are presented. According to updated 2019 ESC Guidelines for the management of patients with SVTs, the treatment options and the algorithms for the management of patients with SVT are shown. What should and should not be done? What’s new in 2019 Guidelines? The antiarrhythmic drugs and their use are given, and the principles of catheter treatment of tachycardia are stated.

Anatomy for right ventricular lead implantation.

To understand the position of a pacing lead in the right ventricle and to correctly interpret fluoroscopy and intracardiac signals, good anatomical knowledge is required. The right ventricle can be separated into an inlet, an outlet, and an apical compartment. The inlet and outlet are separated by the septomarginal trabeculae, while the apex is situated below the moderator band. A lead position in the right ventricular apex is less desirable, last but not least due to the thin myocardial wall. Many leads supposed to be implanted in the apex are in fact fixed rather within the trabeculae in the inlet, which are sometimes difficult to pass. In the right ventricular outflow tract (RVOT), the free wall is easier to reach than the septal due to the fact that the RVOT wraps around the septum. A mid-septal position close to the moderator band is relatively simple to achieve and due to the vicinity of the right bundle branch may produce a narrower paced QRS complex. Special and detailed knowledge is necessary for His bundle and left bundle branch pacing.

ECG at the bedside: atrial fibrillation with randomly narrow and wide QRS complexes

ECG at the bedside: atrial fibrillation with randomly narrow and wide QRS complexes

A TURN IN THE WRONG DIRECTION. WHAT IS MISSING?

Objective: The case highlights the importance of specific non-traditional cardiovascular risk factors in a patient with premature severe cardiovascular disease, despite an apparently adequate control of traditional cardiovascular risk factors. Design and method: Clinical Case. Results: We present the case of a 38 year-old female with Turner syndrome, with cardiovascular risk factors (mild dislypidemia, type 2 diabetes, grade 1 ESC/ ESH hypertension) who presents to the emergency department for newly-onset constrictive chest pain. Her chronic treatment consisted of a low-dose ACEi and metformin. Clinical exam was unremarkable, except for specific clinical phenotype, with normal BP values in both arms and without any signs of congestion. The electrocardiogram showed sinus rhythm of 65 beats/min, narrow QRS, negative T waves in inferior leads, as well a Q wave in lead III. Hs- troponin (1046pg/ml, ULN: 10pg/ml) and NT-proBNP levels (820,9pg/ml) were elevated. Echocardiography revealed a normal ejection fraction, with localized hypokinesia of the inferior wall and no significant valvular disease. The aortic valve was tricuspid and no signs of aortic coarctaction were observed from the suprasternal view. Coronarography was performed, showing significant CAD, with multiple lesions on ADA, LCXA and RCA. The two suboclusive lesions from the RCA were addressed using two drug eluting stents. The evolution was favourable under specific treatment. The baseline levels of LDLc (117 mg/dl) and glycosylated haemoglobin (5,7%) were not as high as we initially expected, given the severe CAD. Furthermore, the ambulatory 24 h BP monitoring after discharge confirmed that the previous treatment with low-dose ACEi was efficient in maintaining the target BP values. Conclusions: Turner syndrome is associated with a variety of cardiovascular manifestations, such as aortic coarctation, which leads to secondary hypertension, as well as an increased risk of cardiovascular events. In our patient, the hypertension was essential, without any arguments for secondary hypertension, as we would have expected. Furthermore, despite the fact the patient exhibited several traditional cardiovascular risk factors, they were controlled within the recommended targets (with the exception of LDLc, slightly higher than 100 mg/dl). The disease duration appears to be critical, as the patient was diagnosed with hypertension more than 15 years ago. We concluded that the advanced premature CAD is most likely the result of the hormonal imbalance and lack of hormone replacement therapy, for which the patient was no longer eligible. Drastic control of traditional cardiovascular risk factors in this case will probably prove to be insufficient.

Simultaneous narrow and wide QRS complex tachycardia: Misdiagnosis or missed diagnosis?

Tachycardia-induced tachycardia, or so-called double tachycardia, appears to be a relatively rare condition. Regardless of the mechanism, this case illustrates the importance of assessing the response to multiple different pacing maneuvers in determining the mechanism of narrow and wide QRS complex tachycardias, rather than relying upon a single maneuver, even one that is believed to be diagnostic. This article is protected by copyright. All rights reserved.