Case report: Short-long-short mechanism triggering sustained ventricular tachycardia in a patient with a single-chamber ICD but inhibiting antitachycardia therapy

Introduction

Short-long-short (SLS) sequences are an important cause of ICD pro-arrhythmia and can initiate both polymorphic and monomorphic ventricular tachycardias (VT). Depending on the programming of a single-chamber ICD, the interplay between SLS sequences and combined VT detection criteria can be responsible for withholding adequate anti-tachycardia pacing (ATP) or shock therapy.

Methods

A 78-year-old patient with ICD was admitted to our emergency department after external cardioversion of a long-lasting VT with hemodynamic compromise. The interrogation of the ICD revealed an SLS sequence initiating a monomorphic VT at a rate of 171 bpm (350 ms). The VT discrimination of the implanted single-chamber ICD was based on the onset and stability criteria as the patient had a history of paroxysmal atrial fibrillation. The ICD was programmed that both criteria had to be met for VT detection and initiation of anti-tachycardia therapy.

Results

Due to the SLS sequence in combination with the programmed VT detection interval, the onset threshold was not fulfilled and inhibited adequate therapy. Some relatively slow VT beats following the SLS sequence resulted finally in a considerable delay in the declaration of the episode onset. As a first step, the threshold for VT detection was programmed to 150 instead of 160 bpm. To avoid SLS sequences and pause-dependent ventricular tachyarrhythmias, VVI backup stimulation was increased from 35 to 55 ppm. Besides, a device-specific algorithm called rate smoothing was activated as a potential preventive feature. On the 3-month follow-up, all sustained VT episodes were detected adequately by the reprogrammed device, resulting in appropriate anti-tachycardia pacing. After further refinement and less aggressive programming of rate smoothing, the patient remained free of symptoms and arrhythmias over a follow-up of more than 2.5 years, particularly since progression to permanent atrial fibrillation and pacing at a lower rate of 60 ppm.

Conclusions

SLS sequences may initiate or trigger VT episodes. Misclassification of the true onset may occur in some ICD devices due to specific programming of VT detection criteria. If both criteria “Onset and Stability” have to be fulfilled, ICD therapy is not delivered despite ongoing VT. Anti-bradycardia backup pacing at a very low stimulation rate may facilitate SLS sequences in patients with ICD resembling a potential pro-arrhythmic mechanism. In case of gradual VT onset with some intervals slower than the programmed VT threshold, the detection rate has to be adjusted down to guarantee appropriate identification of the onset.

Effective reduction of scatter radiation for operator and assistant during coronary procedures with a suspended radiation protection system in a per-procedure live-dosimetry analysis

Background

Interventional cardiologists (IC) are exposed to the highest doses of radiation compared to all other medical specialties. Although head and eyes are exposed to a significant dose of scatter radiation (SCR), precise per-procedure data is sparse. Recently, the EU guidelines for maximum eye lens SCR doses have been reduced from 150 mSv to 20 mSv per year. A ceiling suspended operator radiation protection system has shown additional benefits for SCR protection in radiologic interventional procedures.

Purpose

To study the impact of the ZG system on IC and sterile assistant (SA) SCR exposure when used in addition to the current standard of X-ray protection (SXP) in unselected all-comers cardiologic procedures.

Methods

IC and SA were equipped with Unfors RaySafe i3 live-dosimeters at prespecified locations. 181 consecutive cardiac procedures were recorded, in which either both IC and SA were using SXP (lead apron, thyroid shield) or the IC was using the ZG system and the SA was wearing SXP. In all procedures a suspended lead shield, patient lead cover and an adjustable lead side-shield were present. Diagnostic angiographies (DA) and interventions (PCI) were grouped separately. Within both groups, the IC's and SA's SCR doses were compared.

Results

SCR doses were recorded in 100 DA and 81 PCI procedures. Compared to SXP, the use of the ZG device reduced the average SCR doses per procedure of the IC recorded at the left lateral head from 5.18±1.11 μSv to 0.60±0.07 μSv in DA (−88%; n=49/49, p<0.0001) and from 19.64±3.36 μSv to 1.05±0.28 μSv for PCI (−95%; n=54/23, p=0.0006). The IC's average frontal dose at eye level was reduced from 1.38±0.33 μSv to 0.36±0.04 μSv in DA (−74%; n=50/50, p=0.0033) and from 3.33±0.53 μSv to 0.88±0.20 μSv in PCI (−74%; n=55/25, p=0.0031). Consistently, the dose recorded immediately under the IC's left shoulder were reduced from 34.14±7.79 μSv to 1.59±0.32 μSv in DA (−95%; n=39/40, p=0.0001) and from 71.77±10.77 μSv to 3.95±0.83 μSv in PCI (−94%; n=44/23, p=0.0001). Furthermore, when the IC used the ZG system, the average SCR dose recorded at the SA's head was reduced from 4.32±0.98 μSv to 2.11±0.28 μSv in DA (−51%, n=45/49, p=0.027) and from 18.55±2.69 μSv to 6.93±1.93 μSv in PCI (−63%, n=54/24, p=0.0078). With the exception of the IC frontal dose, all SCR dose effects remained significant after correction for total radiation time (μSv/s) and dose-area product (μSv/Gy·cm2). Procedure duration, contrast use and patient radiation dose were not affected by ZG use.

Conclusions

In a representative all-comers cohort of cardiac procedures, the ZG X-ray protection system demonstrated an impressive potential for SCR reduction in critical anatomical areas - even in a state-of-the-art cath-lab inventory with multiple SCR reduction measures already in place. Remarkably, the protective effect also included the sterile assistant at the table wearing SXP.

Funding Acknowledgement

Type of funding sources: None.

Safe application of extensive radiotherapy to a cardiac resynchronization device

Patients with cardiac implantable electronic devices undergoing radiotherapy (RT) are prone to the risk of device failure. Guidelines and manufacturer's instructions are lacking practical recommendations for cumulative radiation doses to pacemakers or implantable cardioverter defibrillators. The present case demonstrates the effect of RT of a Merkel cell carcinoma near the location of a cardiac resynchronization therapy pacemaker. Despite guideline recommendations, surgical relocation or de novo implantation of the device on the contralateral side was avoided to prevent the dissemination of tumour cells, inflammation, and wound healing complications. A total dose of 47.25 Gy applied in very close proximity to the cardiac resynchronization therapy pacemaker was carried out safely without jeopardizing the patient and any device malfunction during and after treatment within >1.5 years of follow‐up period. The present case demonstrates that high‐dose RT near to a cardiac resynchronization therapy device can be carried out safely. Special precautions during RT as well as close device follow‐up interrogations are mandatory. Large‐scale studies are needed for the true frequency of adverse events.

Emerging trends in cardiovascular research: HFpEF in the spotlight. A bibliometric analysis of the years 2009-2016

INTRODUCTION

Up to 50% of patients suffering from acute decompensated heart failure show normal or slightly reduced left ventricular ejection fraction (LVEF). This syndrome, which is known as heart failure with preserved ejection fraction (HFpEF) is associated with increasing age. Epidemiological studies could portrait an increasing importance and an even emerging prevalence in the past decades. Still, there is currently no evidenced based medical treatment option available. Our aims were to identify upcoming trends and emerging concepts and to point out important centers in the global research of HFpEF.

EVIDENCE ACQUISITION

We performed a bibliometric study on current science in the field of HFpEF to identify study characteristics, impact factors and the countries of origin of basic and clinical studies that were published within the years 2009 to 2016. We further prepared density equalizing maps for visualization of the obtained data.

EVIDENCE SYNTHESIS

A total of 5413 studies was screened, of which 794 were found eligible. The scientific output in clinical studies rose from 25 in 2009 to 165 in 2016. Most of the publications had a clinical topic, followed by studies on new imaging techniques. Basic research trials were by far beyond. The USA, Japan and Germany were identified as the most important national contributors to global scientific output.

CONCLUSIONS

This first bibliometric study in the field of HFpEF shows a substantial increase of research within the last decade, mainly in the USA, Japan, and continental Europe. As an ongoing therapeutic trend in this field, we identified RAAS-blockade and 5-phosphodiesterase-inhibition.

Delayed high-grade atrioventricular block requiring pacemaker implantation in a multiple sclerosis patient treated with fingolimod

Fingolimod is a sphingosine-1-phosphate 1 (S1P1) modulator which retains lymphocytes in secondary lymphoid organs and is approved for the treatment of relapsing multiple sclerosis (MS). The decrease of heart rate and AV block are reversible side-effects of treatment initiation. We report a case of persistent high-grade atrioventricular (AV) block 450 days after start of fingolimod and permanent pacemaker requirement in late-onset relapsing multiple sclerosis (MS). We discuss emerging risk factors for cardiac conduction deficits including the recently discovered vagomimetic effects of S1P1 modulation, structural brain and spinal cord damage, ageing and comorbidities.

Association Between Vascular Cell Adhesion Molecule 1 and Atrial Fibrillation

Importance

Accumulating evidence links inflammation and atrial fibrillation (AF).

Objective

To assess whether markers of systemic and atrial inflammation are associated with incident AF in the general population.

Design, Setting, and Participants

The Bruneck Study is a prospective, population-based cohort study with a 20-year follow-up (n = 909). The population included a random sample of the general community aged 40 to 79 years. Levels of 13 inflammation markers were measured at baseline in 1990. Findings were replicated in a case-control sample nested within the prospective Salzburg Atherosclerosis Prevention Program in Subjects at High Individual Risk (SAPHIR) study (n = 1770). Data analysis was performed from February to May 2016.

Exposures

Levels of 13 inflammation markers.

Main Outcomes and Measures

Incident AF over a 20-year follow-up period in the Bruneck Study.

Results

Of the 909 participants included in the Bruneck Study, mean [SD] age was 58.8 (11.4) years and 448 (49.3%) were women. Among the 880 participants free of prevalent AF (n = 29) at baseline, 117 developed AF during the 20-year follow-up period (incidence rate, 8.2; 95% CI, 6.8-9.6 per 1000 person-years). The levels of soluble vascular cell adhesion molecule 1 (VCAM-1) and osteoprotegerin were significantly associated with incident AF (hazard ratio [HR], 1.49; 95% CI, 1.26-1.78; and 1.46; 95% CI, 1.25-1.69, respectively; P < .001 with Bonferroni correction for both), but osteoprotegerin lost significance after age and sex adjustment (HR, 1.05; 95% CI, 0.87-1.27; P > .99 with Bonferroni correction). Matrix metalloproteinase 9, metalloproteinase inhibitor 1, monocyte chemoattractant protein-1, P-selectin, fibrinogen, receptor activator of nuclear factor-κB ligand, high-sensitivity C-reactive protein, adiponectin, leptin, soluble intercellular adhesion molecule 1, and E-selectin all fell short of significance (after Bonferroni correction in unadjusted and age- and sex-adjusted analyses). The HR for a 1-SD higher soluble VCAM-1 level was 1.34 (95% CI, 1.11-1.62; Bonferroni-corrected P = .03) in a multivariable model. The association was of a dose-response type, at least as strong as that obtained for N-terminal pro-B-type natriuretic peptide (multivariable HR for a 1-SD higher N-terminal pro-B-type natriuretic peptide level, 1.15; 95% CI, 1.04-1.26), internally consistent in various subgroups, and successfully replicated in the SAPHIR Study (age- and sex-adjusted, and multivariable odds ratios for a 1-SD higher soluble VCAM-1 level, 1.91; 95% CI, 1.24-2.96, P = .003; and 2.59; 95% CI, 1.45-4.60; P = .001).

Conclusions and Relevance

Levels of soluble VCAM-1, but not other inflammation markers, are significantly associated with new-onset AF in the general community. Future studies should address whether soluble VCAM-1 is capable of improving AF risk classification beyond the information provided by standard risk scores.

Elevated plasma levels of interleukin-16 in patients with acute myocardial infarction

Interleukin (IL)-16, a polypeptide cytokine, plays a crucial role in the inflammatory process, acting as a chemoattractant for peripheral immune cells and has been linked to various inflammatory diseases. However, its role in patients with acute myocardial infarction (AMI) is unclear.We retrospectively analyzed serum levels of IL-16 in blood of patients with (STEMI, n = 45) and without ST-segment elevation myocardial infarction (NSTEMI, n = 42) compared with controls with excluded coronary artery disease (n = 55). Furthermore, correlation analysis with inflammatory cells, C-reactive protein (CRP) levels, dendritic cell precursors (DCPs), and other clinical and biochemical markers was performed.Compared with controls, patients with STEMI and NSTEMI evidenced higher levels of IL-16 in pg/mL (STEMI: 759.38 ± 471.54, NSTEMI: 677.77 ± 438.8, control: 500.45 ± 432.21; P = .002). IL-16 correlated with CRP (r = 0.26, P = .001), leucocytes (r = 0.38, P < .001), NT-proBNP (r = 0.20, P = .02) and hsTnT (r = 0.25, P = .004). Circulating myeloid DCPs, plasmacytoid DCPs, and total DCPs showed a significant inverse correlation to IL-16 levels (r = -0.21, P = .01; r = -0.23, P = .005; r = -0.26, P = .002, respectively).Interleukin-16 might play an important role in the inflammatory process of patients suffering from AMI and correlates with inflammatory cell activation and clinical and biochemical markers. The cytokine IL-16 might upregulate the proinflammatory response and recruitment of inflammatory cells into infarcted myocardium.

A comparative analysis of novel cardiovascular biomarkers in patients with chronic heart failure

BACKGROUND

Heart failure (HF) with reduced ejection fraction remains a major therapeutic challenge. The aim of this study was to investigate the role of novel cardiovascular biomarkers, i.e. soluble suppression of tumorigenicity (sST2), growth-differentiation factor-15 (GDF-15), soluble urokinase plasminogen activator receptor (suPAR) and heart-type fatty acid binding protein (H-FABP) in patients with ischaemic (ICM) or dilative cardiomyopathy (DCM).

MATERIALS AND METHODS

A total of 200 patients were enrolled in this study: 65 were diagnosed with DCM and 59 patients suffering from ICM were included. 76 patients without coronary artery disease or signs of heart failure were included as controls. Plasma samples of all patients were analyzed by use of ELISA.

RESULTS

Levels of sST2, suPAR and H-FABP were significantly higher in ICM and DCM patients compared to the control group (p<0.0001). However, there were no significant differences between ICM and DCM in biomarker levels. Ejection fraction correlated inversely with cardiac biomarkers (sST2 p<0.0001, GDF-15 p=0.0394, suPAR p=0.0029, H-FABP p<0.0001). Similarly, CRP levels also showed a positive correlation with cardiac biomarkers. Renal insufficiency (p<0.0001) and diabetes (sST2 p=0.0021, GDF-15 p=0.0055, suPAR p=0.0339, H-FABP p=0.0010) were significantly associated with a rise in cardiac biomarkers.

CONCLUSION

Novel cardiovascular biomarkers such as ST2, GDF-15, uPAR and H-FABP could offer a great potential for more precise diagnostic in ICM and DCM patients. H-FABP was the most promising marker in our study, followed by sST2, uPAR and GDF-15. Additional prospective studies will be necessary to further evaluate the potential clinical benefits in routine treatment of HF.

High peak PaO2 values associated with adverse outcome in patients treated with noninvasive ventilation for acute cardiogenic pulmonary edema and pneumonia

BACKGROUND

Noninvasive ventilation (NIV) has a sigificant impact on mortality in acute respiratory failure (ARF). Predictive parameters for mortality are of high interest.

METHODS

We retrospectively analyzed 3759 blood gas analysis and clinical parameters of 475 patients presenting with ARF based on acute cardiogenic pulmonary edema and/or pneumonia. The influence of peak arterial oxygen partial pressure levels (PaO2) with respect to its predictive value for in-hopital and long-term mortality was investigated.

RESULTS

Overall intra-hospital mortality was 24%. Peak PaO2 levels in kPa were significantly higher in non-survivors (20.01±10.11) compared to survivors (15.65±6.79, P<0.001). A univariate Cox proportional-hazards analysis for long-term mortality revealed associations with maximum PaO2 levels (overall cohort: HR= 1.02; 95% CI: 1.007-1.03; P=0.003; CPE: HR= 1.02; 95% CI: 0.99-1.04, P=0.05, pneumonia: HR= 1.02; 95% CI: 1-1.4, P=0.02). A PaO2 cut-off value of 13 kiloPascal (kPa) was calculated by means of Youden Index and remained true even after correction for APACHE 2 Score (HR= 1.50; 95% CI: 1.00-2.25; P=0.05) and for PaCO2 (HR= 1.63; 95% CI: 1.14-2.33; P=0.01).

CONCLUSIONS

Peak PaO2 levels were associated with worse in-hopital and long-term mortality in patients treated with NIV due to ARF. These findings may indicate that application of high oxygen may be detrimental in such patients.

Impact of Moderate Altitude on Pro-Inflammatory Cytokines in Healthy Volunteers

BACKGROUND

The induction of microvascular inflammation and the effects on cytokine production in blood due to hypoxia has been shown in the past. We have previously reported a statistically significant increase of the pro-inflammatory cytokine interleukin-8 (IL-8) in normobaric hypoxia in the setting of a hypoxia-chamber. In the present study, we sought to analyze plasma levels of inflammatory cytokines in a real-life stetting in order to foster our knowledge on hypoxia induced microvascular inflammation at moderate altitude.

METHODS

Pro-inflammatory cytokines (IL-8, IL-6, TNF-α) were measured in an experimental field study, exposing 18 healthy volunteers to moderate hypoxia while staying at a mountain lodge in Diavolezza, Switzerland (2978 meters above sea level). Plasma cytokine levels were measured by ELISA.

RESULTS

In contradiction to our results in a normobaric hypoxia-chamber, exposure to moderate hypoxia led to a significant decrease of plasma IL-8 levels in a real-life setting (from 2.902 (1.046 - 4.984) pg/mL to 1.395 (0.698 - 3.712) pg/mL, p = 0.034). Concentrations of IL-6 and TNF-α did not show statistically significant changes in comparison to baseline measurements.

CONCLUSIONS

The results of this study show a decrease of proinflammatory cytokine IL-8 in a real life setting of moderate altitude in healthy individuals. Initiation of angiogenesis or subliminal stimulus for an altitude-induced inflammatory reaction may be explanations for this unexpected finding.

Multibiomarker analysis in patients with acute myocardial infarction

BACKGROUND

Novel biomarkers representing different pathobiological pathways and their role in patients with acute myocardial infarction (AMI) were studied.

METHODS

We retrospectively analysed serum levels of soluble suppression of tumorigenicity (sST2), growth-differentiation factor-15 (GDF-15), soluble urokinase plasminogen activator receptor (suPAR), heart-type fatty acid-binding protein (H-FABP) and plasma fetuin A in blood of patients with AMI (STEMI, n = 61; NSTEMI, n = 57) compared to controls with excluded coronary artery disease (n = 76). Furthermore, detailed correlation analysis was performed.

RESULTS

Compared with controls, in patients with STEMI and NSTEMI higher levels expressed as median of sST2 in pg/mL (STEMI: 13210·9, NSTEMI: 11989·1, control: 5248; P < 0·001), GDF-15 in pg/mL (STEMI: 818·8, NSTEMI 677·5, control 548·6; P < 0·001), suPAR in pg/mL (STEMI: 3461·1, NSTEMI: 3466·7, control: 2463·6; P < 0·001), H-FABP in ng/mL (STEMI: 5·8, NSTEMI: 5·4, control: 0·0; P < 0·001) and lower plasma fetuin A levels in μg/mL (STEMI: 95, NSTEMI: 54, control: 116·6; P < 0·001) were detected. Correlation analysis found clinical and biochemical parameters such as ejection fraction, length of hospital stay, creatine kinase, NT-proBNP and hs Troponin T levels as well as inflammatory markers (CRP, leucocytes) to be significantly correlated with novel biomarkers.

CONCLUSION

Plasma levels of novel biomarkers were significantly elevated (sST2, GDF-15, H-FABP, suPAR) or inversely downregulated (fetuin A) in patients with AMI compared to a control group with excluded coronary artery disease. Significant correlations with various clinical parameters and standard biochemical markers were found.

The influence of cavotricuspid isthmus length on total radiofrequency energy to cure right atrial flutter

BACKGROUND AND AIM

The complexity and success rate of right atrial flutter ablation is highly dependent on anatomical structures.

METHODS

The study comprised 35 consecutive patients (33-77 years old; 30 men) who underwent ablation of typical atrial flutter. The linear ablation line was measured offline as a surrogate for the cavotricuspid isthmus (CTI) length with the help of a three-dimensional mapping and navigation system (Ensite™). Biophysical parameters, such as total radiofrequency (RF) energy and time of the ablation procedure, were analysed to test the hypothesis that any of these variables show a correlation with the length of the ablation line.

RESULTS

Bidirectional isthmus block was achieved in all cases. The isthmus length had a mean value of 32 ± 12 mm with a range of 14-57 mm. The linear regression between the CTI length and the total RF energy was not significant. There was no significant difference in energy (32.281 ± 25.587 vs. 37.136 ± 24.250 W-s, p = NS) or in the total ablation time (759 ± 646 vs. 802 ± 533 s, p = NS) between the group with short (< 29 mm; n = 17) vs. long CTI (≥ 29 mm, n = 18). When comparing different ablation technologies, total RF energy delivered with 8-mm catheter technology (group I) was significantly lower than in patients with cross over from 8-mm to cooled ablation technology (group III) (29.615 ± 12.331 vs. 62.674 ± 28.735 W-s, p = 0.01). The same was true for the comparison between cooled ablation technology (group II) and group III (19.879 ± 13.669 vs. 62.674 ± 28.735 W-s, p = 0.002).

CONCLUSIONS

The length of the CTI as measured with help of a three-dimensional mapping system may reflect only a weak indicator for the complexity of flutter ablation procedures. The thickness of musculature and specific anatomy of the CTI seem to be the main challenges in performing a linear ablation to achieve bidirectional block.

Coexistence of atrioventricular nodal reentrant tachycardia with other forms of arrhythmias

OBJECTIVE

The aim of this retrospective study was to investigate the association of atrioventricular nodal reentrant tachycardia (AVNRT) with other forms of arrhythmia in individual patients and its consequences for treatment.

SUBJECTS AND METHODS

This study comprised 493 consecutive patients aged 16-88 years (296 women and 197 men) who were diagnosed with a form of AVNRT via a standard 4-catheter electrophysiological study (EPS). Patients were clinically followed (range 0.5-12 years) at a single center.

RESULTS

Coexistence of AVNRT with other types of tachycardias was observed in 197 (40%) patients. Atrial fibrillation was found most frequently in 94 (19%) patients as follows: focal atrial tachycardia, n = 40 (8%); atrial flutter, n = 32 (6%), and AV reentrant tachycardia, n = 22 (4%). Double tachycardia was present in 140 (30%) patients, and more than 2 different types of tachycardias were present in 57 (12%) patients. Transitions between AVNRT and other tachycardias occurred in 25 (5%) patients. Two or more tachycardias were ablated in 42 (9%) patients. The majority of patients were free of symptoms at the first follow-up, whereas 130 (26%) patients reported a variety of symptoms.

CONCLUSION

Coexistence of AVNRT with other types of arrhythmias was a common finding among these patients. The most frequently observed double tachycardia was the combination of AVNRT with atrial tachyarrhythmias, such as atrial fibrillation, with a potential significance for further patient management.

Physiotherapy as a Rare Cause of Twiddler's Syndrome in a Patient With an Implanted Cardioverter Defibrillator

A 65-year-old male patient with a history of ischemic cardiomyopathy developed ventricular tachycardia resulting in presyncope. An ICD was indicated for secondary prophylaxis of ventricular tachyarrhythmias. A dual chamber ICD was implanted from the right side because insertion of the device from the left side was unfeasible after surgery of a left subscapularis tendon lesion. ICD implantation and testing of defibrillation threshold were uneventful. During early follow-up a progressive increase of the stimulation threshold was detected. On chest X-ray coiling of both atrial and ventricular leads was noted and caused inadvertently by active shoulder-arm physiotherapy. Complete revision of the ICD system was necessary for restoration of the pacemaker function of the ICD. This unique case highlights important steps for early recognition and prevention of Twiddler’s syndrome that may occur due to physiotherapy treatment even without abnormal manipulations by the patient.

Lower body mass index and atrial fibrillation as independent predictors for mortality in patients with implantable cardioverter defibrillator

AIM

To evaluate risk factors related to total mortality in an unselected population of patients implanted with a cardioverter defibrillator.

METHODS

Survival analysis was performed retrospectively investigating the records of 77 consecutive patients implanted with defibrillators (median 67 years, range 38-83 years; 63 men). All patients were followed regularly in 3-month intervals. The cause of mortality was assessed clinically, including post-mortem examination of device to assess possible arrhythmogenic death. Predictors were assessed by Kaplan-Meier analysis with log-rank tests and by Cox regression analysis (proportional hazards).

RESULTS

Defibrillator recipients had a mean (+/-standard deviation) ejection fraction of 34+/-13%, left ventricular end-diastolic dimension (LVEDD) of 6.24+/-0.8 cm, QRS duration of 129+/-34 ms, and body mass index (BMI) of 26.4+/-4.3 kg/m(2). Atrial fibrillation was present in 32 patients, paroxysmal fibrillation in 23, and permanent fibrillation in 9 patients. The estimate of mean survival time for all patients was 51.5 (95% confidence interval 46.6-56.5) months. During the study period 11/77 (14%) patients died. Mean follow-up time was 24.5 months (range 0.2-60.7) for survivors and 7.6 months (range 1.5-42) for non-survivors. Independent predictors of mortality were the NYHA class (P=0.004), BMI< or =26 kg/m(2) (P=0.024), presence of paroxysmal or permanent atrial fibrillation (P=0.014), and absence of arterial hypertension (P=0.010). LVEDD showed a weak significant effect on survival (P=0.049).

CONCLUSION

Patients with implantable cardioverter defibrillator and a normal to lower BMI or atrial fibrillation had a significantly higher overall mortality. These factors may be indicative of end stage heart failure or diseases associated with high sympathetic activation.

Limited dose-effect relationship of adenosine for detection of atrioventricular nodal duality in patients with supraventricular tachycardias

OBJECTIVE

The purpose of the study was to test the dose-effect relationship of adenosine for the diagnosis of dual atrioventricular (AV) nodal physiology in patients presenting with supraventricular tachycardia.

SUBJECTS AND METHODS

The study population consisted of 57 patients (mean age 50 +/- 14 years; 36 females, 21 males) with palpitations related to supraventricular tachycardia. Adenosine was injected as bolus during sinus rhythm at rest in order to unmask dual AV nodal physiology by a PR jump on surface ECG (defined as a sudden increase by > or = 50 ms measured from the onset of the P-wave to the R-wave between two consecutive sinus beats). According to a stepwise clinical approach, adenosine was administered as bolus in incremental dosages (6 mg followed by 12 mg, if necessary up to 18 mg). Once a PR jump > or = 50 ms or a high-grade AV block was noted on surface ECG, the injection was stopped at that dose.

RESULTS

A significant PR jump was noted after injection of 6 mg (n = 21, 99 +/- 30 ms) or 12 mg (n = 13, 94 +/- 35 ms), but not after 18 mg (n = 4, 35 +/- 10 ms) adenosine. Provocation of temporary first-grade AV block (n = 13) was associated with the longest increment of PR interval, whereas high-grade AV block (n = 36) produced a significantly shorter PR jump (105 +/- 35 vs. 65 +/- 40 ms, p = 0.0024). Electrophysiological study and ablation were performed in 37 highly symptomatic patients. AV nodal reentrant tachycardia was diagnosed in 33 patients and orthodromic AV reentrant tachycardia in 4 patients.

CONCLUSION

The adenosine test was characterized by a reverse dose-effect relationship as far as identification of AV nodal duality was concerned.

Simultaneous angiographic imaging of ipsilateral pulmonary veins for catheter ablation of atrial fibrillation

Various imaging techniques are nowadays in clinical use to obtain important information about pulmonary vein (PV) anatomy in patients undergoing catheter ablation of atrial fibrillation (AF). Although some controversy exists about the optimal approach for catheter ablation of AF in recent times, knowledge of the individual left atrial-PV anatomy remains a basic feature of the different ablational techniques. Angiographic delineation of PV ostia has become an integral part of the PV isolation procedure, mainly in order to avoid potentially harmful PV stenosis. Selective venography with angiocatheters is well documented and widely available but has its own limitations, particularly with respect to visualization of the atriovenous junctions. The present report summarizes the usefulness, safety and feasibility of a new angiographic technique for simultaneous imaging of ipsilateral PVs applicable during catheter ablation of AF. Electrophysiologically guided segmental PV isolation was accomplished in 31 patients mostly with paroxysmal atrial fibrillation, who experienced significant clinical improvement during a followup of 17 +/- 15 months. The angiographic technique was effective for assessment of the individual anatomy including common ostia and supernumerary veins which can be easily missed by selective venography. Variant PV ostia were identified in about 20% of patients; particularly the presence of a left common trunk was challenging for the segmental ablation strategy. Angiographic detection of variant PV anatomy was comparable to visualization with computer tomography performed at 4-months follow-up. Finally, this type of angiographic imaging performed at the time of catheter ablation may help to reduce the risk of significant PV stenosis.

T-Wave Oversensing by an Implantable Cardioverter Defibrillator after Successful Ablation of Idiopathic Ventricular Fibrillation

Focal ablation of trigger premature ventricular complexes (PVCs) from the Purkinje system helped to suppress idiopathic ventricular fibrillation (VF) in an athlete who had suffered from frequent appropriate shock therapies. However, only a few days after successful ablation T-wave oversensing occurred during exercise and resulted in repetitive distressing defibrillator shocks. Despite lack of any changes on the surface ECG, the endocardially recorded electrogram revealed an unfavorable ratio of R-to-T-wave amplitude predisposing to double counting with accelerated heart rates. This case illustrates that T-wave oversensing may complicate the clinical course after successful ablation of malignant Purkinje ectopy.

Blanked Atrial Flutter in Patients with Cardiac Resynchronization Therapy: Clinical Significance and Implications for Device Programming

BACKGROUND

Atrial arrhythmias are frequently observed in patients with heart failure and may be a primary cause for decompensation during cardiac resynchronization therapy (CRT). The accurate detection of organized atrial tachyarrhythmias poses a challenge to the function of mode-switching biventricular pacemakers/defibrillators.

METHODS

The purpose of the study was to determine retrospectively the incidence of blanked atrial flutter and mode switch failure (2:1 lock-in), and to look for factors predisposing to this problem. A total number of 65 patients with CRT devices has been followed regularly over 18 +/- 12 months. Five patients were excluded because of chronic atrial fibrillation and reprogramming to VVIR mode.

RESULTS

Seven out of 60 patients (12%) were diagnosed with blanked atrial flutter at unscheduled device interrogation. Sustained biventricular pacing at a median rate of 125/min-mimicking sinus tachycardia-resulted in rapid deterioration of heart failure and hospitalization. Mode switch failure occurred due to coincidence of every second flutter wave with atrial blanking. The group with 2:1 lock-in was programmed to longer atrial blanking times (143 +/- 34 ms vs 105 +/- 32 ms; P = 0.026) and AV intervals (126 +/- 8 ms vs 107 +/- 29; P = 0.001) than the group without lock-in. Other clinical characteristics examined did not differ between the two groups apart from a previous history of atrial fibrillation (P = 0.032).

CONCLUSION

Blanked atrial flutter with rapid ventricular pacing is a clinically important problem in heart failure patients treated with CRT devices. Efforts should be made to avoid this complication by atrial lead implantation without ventricular farfield oversensing, by programming short PVAB and AV intervals, and by implementation of dedicated device algorithms.

Multiple appropriate and spurious defibrillator shocks in a patient with right ventricular cardiomyopathy

An implantable cardioverter defibrillator (ICD) has been implanted in a 69-year-old patient with arrhythmogenic right ventricular cardiomyopathy (ARVC) for treatment of syncopal ventricular tachycardia (VT). Two types of ICD-related emergencies complicated the clinical course within 15 months. The first arrhythmic event occurred 3 months after ICD implantation as electrical storm with repetitive fast VT, resulting in 87 consecutive shocks at maximal output. Intravenous administration of amiodarone and reprogramming of the device were the measures to control VT. A year later, the patient experienced a cluster of 97 inappropriate shocks. Lead insulation failure produced electrical noise on the ventricular sensing channel and was misidentified as ventricular fibrillation (VF). The depleted ICD and the dual-coil lead were explanted and replaced by a new system. Multiple ICD shocks constitute a medical emergency in ICD patients, which requires immediate device interrogation for differentiation of appropriate and spurious discharges.

Electrocardiographic changes at the onset of epileptic seizures

PURPOSE

We studied heart-rate (HR) changes at the transition from the preictal to the ictal state in patients with focal epilepsies to gain some insight into the mechanisms involved in the neuronal regulation of cardiovascular function.

METHODS

We assessed ECG changes during 145 seizures recorded with scalp EEG in 58 patients who underwent video-EEG monitoring. Consecutive RR intervals were analyzed with a newly developed mathematical method for a total of 90 s.

RESULTS

Ictal-onset tachycardia occurred in 86.9% of all seizures, whereas bradycardia was documented only in 1.4%. The incidence as well as the amount of ictal HR increase was significantly more pronounced in patients with mesial temporal lobe epilepsy (TLE) as compared with those with non-lesional TLE or extratemporal epilepsy. Moreover, right hemispheric seizures were associated with ictal-onset tachycardia. On average, ictal HR increase preceded EEG seizure onset by 13.7 s in TLE patients and 8.2 s in patients with extratemporal epilepsy. This difference was significant. Ictal HR changes could be classified according to their temporal evolution into two different patterns. These two patterns differed significantly between the temporal lobe and the extratemporal epilepsy patient group.

CONCLUSIONS

Epileptic discharges directly influence areas of the central autonomic network, thus regulating HR and rhythm. Such changes occur before ictal discharges appear on surface electrodes. Our newly developed method may be of potential use for clinical applications such as automatic seizure-detection systems. Moreover, our method might help to clarify further the basic mechanisms of interactions between heart and brain.

Paroxysmal supraventricular tachycardia with persistent ventriculoatrial block

We report the case of a 64-year-old patient with paroxysmal supraventricular tachycardia and persistent VA block. Induction and maintenance of tachycardia occurred without apparent activation of the atria. Diagnostic characteristics were most compatible with AV nodal reentrant tachycardia (AVNRT). Automatic junctional tachycardia and orthodromic nodoventricular or nodofascicular reentry tachycardia were considered in the differential diagnosis. Upper common pathway block during AVNRT may be explained by either intra-atrial conduction block or purely intranodal confined AVNRT. The arrhythmia was cured by a typical posteroseptal ablation approach guided by slow pathway potentials.

Autonomic epilepsy--the influence of epileptic discharges on heart rate and rhythm

PURPOSE

To study cardiac alterations (changes in heart rate and cardiac arrhythmias) at the transition from the pre-ictal to the ictal state during focal epileptic seizures.

METHODS

We assessed ECG changes during 92 seizures recorded with scalp EEG in 30 patients and 35 seizures in 11 patients evaluated with subdural strip and/or grid electrodes. Consecutive RR intervals were analyzed with a newly developed mathematical model for a total of 90 seconds (60 seconds pre-ictal, 30 seconds ictal).

RESULTS

We found an ictal tachycardia (heart rate increase > 10 bpm) in 82.5% of seizures, and an ictal bradycardia (heart rate decrease > 10 bpm) in 3.3% of seizures. Bradycardia was only observed in seizures of frontal lobe origin. Heart rate changes occurred several seconds prior to EEG seizure onset on scalp-EEG in 76.1% of seizures, but also prior to EEG seizure onset on invasive EEG in 45.7% of seizures. Early tachycardia occurred significantly more often in temporal than in frontal lobe origin seizures. We found no significant effect of the side of seizure onset on both the quality and quantity of ictal heart rate changes. The occurrence of an aura or of awakening prior to the seizure had no influence on peri-ictal heart rate changes. Low risk cardiac arrhythmias were more frequently observed in frontal lobe origin seizures.

CONCLUSIONS

Epileptic discharges directly influence portions of the central autonomic network, within a brain area too small or too deep to be detected on EEG, most likely deep mesial structures such as the amygdala or portions of the hippocampus. The potential clinical applications of our results include (1) automatic seizure detection, (2) differentiation between seizures of temporal and frontal lobe origin, (3) detection of peri-ictal cardiac arrhythmias, and (4) clarification of SUDS (sudden unexplained death syndrome) in epilepsy.