Quantifying the variability of bipolar voltage amplitude with sensing angle in residual conduction isthmuses in atrial scar

Funding Acknowledgements

Type of funding sources: Private company. Main funding source(s): Abbott

Background

The angle between the activation wavefront and bipole may conceal the conduction isthmus in conventional bipolar voltage mapping, but the extent of variability of electrogram (EGM) voltage amplitude with directional changes has not been quantified.

Purpose

Using a well-defined model of discrete atrial conduction, we sought to use Omnipolar Technology (OT) to assess variability of voltage amplitude as a function of sensing angle, in sites of residual conduction and scar tissue.

Methods

During redo pulmonary vein isolation (PVI) procedures, baseline voltage maps were acquired during coronary sinus pacing (500 ms) using a rectangular 16-pole catheter (HD Grid). During retrospective analysis with OT research software, all EGM’s ≤1 cm radius from the site of PVI were classified as GAP (vs No-GAP; Panel A) The variability of voltage amplitude (OT-ΔV) with sensing angle (θ) was computed as the difference between the maximum and minimum voltages (OT-Vmax - OT-Vmin), in both GAP and No-GAP subregions (Panels A & B).

Results

23 GAP sites were identified in 12 of 15 consecutive patients studied. 3464 EGM’s (1386 GAP vs 2078 No-GAP) were analyzed. Global mean OT-ΔV was 0.46±0.80 mV. GAP regions showed significantly (P<0.0001) higher OT-ΔV as compared with No-GAP regions (0.80±1.03 mV vs 0.24±0.47 mV respectively; Panel C) The mean Δθ angle for OT-ΔV was similar in both GAP and No-GAP regions (88.6±11.3° vs 88.0±13.6°, P=0.1; Panel D).

Conclusion

The variability of voltage amplitude as a function of bipole orientation can be significant, especially in GAP regions (0.80±1.03 mV). (2) OT-ΔV holds promise for identification of residual conduction within atrial scar tissue.

Influence of atrial cycle length and site of origin on the peak frequency of bipolar electrograms to discriminate isthmus conduction in atrial scar

Funding Acknowledgements

Type of funding sources: Private company. Main funding source(s): Abbott

Background

Peak frequency (PF) of conventional bipolar electrograms is a novel parameter which may distinguish between near-field (NF) and far-field (FF) signals. However, the influence of activation rate and the direction of the activation front on it is unknown.

Purpose

1. To study the influence of atrial cycle length and wavefront origin on PF to detect residual conduction in a well-defined model of narrow isthmus of conduction such as subacute pulmonary vein (PV) reconnection following atrial fibrillation ablation. 2. To compare this influence with that found for Bipolar voltage (BiV).

Methods

Baseline maps were acquired in redo PV isolation (PVI) procedures with a 16-pole grid catheter (HD-Grid) during low rate sinus rhythm (SR), low rate coronary sinus pacing at 500 ms cycle length (CSLR) and high rate coronary sinus pacing at 300 ms cycle length (CSHR). PFs were retrospectively computed. PVI sites requiring ≤3 radiofrequency applications were included, with EGMʼs ≤1cm from the PVI site classified as GAP (vs >1cm, No-GAP).

Results

28 GAPs were found in 12 of 14 consecutive patients in the study. 3976 EGMʼs (1547 GAP vs 2429 No-GAP) were analyzed. In both GAP and No-GAP, PF was similar in SR vs CSLR (GAP: 363±132 Hz -SR vs 345±135 Hz -CSLR, P=NS ; No-GAP: 196±110 Hz -SR vs 181±116 Hz -CSLR, P=NS). PF was slightly higher for CSLR vs CSHR. (GAP: 345±135 Hz -CSLR vs 317±154 Hz -CSHR, P<0.001; No-GAP 181±116 mV -CSLR vs 162±129 mV -CSHR, P<0.01). (Panel A). BiV was significantly higher in SR vs CS pacing but similar between CSLR and CSHR (GAP: 1.86±2.11 mV -SR vs 0.87±1.19 mV -CSLR vs 0.74±0.92 mV -CSHR, P= NS, No-GAP: 0.62±1.22 mV -SR vs 0.33±0.68 mV - CSLR vs 0.27±0.48 mV - CSHR, P=NS. (Panel B). ROC GAP discrimination for PF was similar between SR and CSLR (AUCʼs: 0.86-SR, 0.84-CSLR) and slightly lower for CSHR (AUC: 0.81) with optimal cutoffs of 260, 240 and 220 Hz, respectively. ROC GAP discrimination for BiV was lower vs PF in all rhythm modes (AUCʼs: 0.77-SR, 0.74-CSLR, 0.75-CSHR), with optimal cutoffs of 0.3, 0.2 and 0.15 mV, respectively.

Conclusion

ROC gap discrimination was significantly higher for all rhythm modes with PF vs BiV. PF showed slightly decreasing cutoff values for SR, CSLR and CSHR respectively, whereas BiV showed a greater relative decrease in cutoffs for SR, CSLR and CSHR.

Atrial imaging and cardiac rhythm in cryptogenic embolic stroke: a preliminary analysis of the ARIES study

Funding Acknowledgements

Type of funding sources: None.

Background

Cryptogenic stroke is frequently related to cardioembolic source previously unknown. We aim to analyze atrial fibrillation (AF), parafibrilatory status (para-AF) and echocardiographic signs of atrial dysfunction in patients (p) with cryptogenic stroke.

Methods

Consecutive p with cryptogenic stroke were prospectively enrolled in the on-going study ARIES (Atrial Imaging and cardiac Rhythm In Embolic Stroke). Cardiologic work-up includes external wearable 2-lead ECG monitoring system for 30 days (non-AF, AF, para-AF defined as >3000 atrial ectopic beats/day or >2 "micro-AF" episodes (fibrillatory burst <30 s)/day) and advanced left atrial echocardiography (signs of atrial dysfunction as strain during three phases -reservoir, conduit, and contractile-). The first monitoring was started before hospital discharge, p without AF in the first monitoring and without extremely disabling neurologic sequelae underwent a further 30 days monitoring. We describe stroke recurrence at 90 days follow-up, and we compare echocardiographic signs of atrial dysfunction according to rhythm study.

Results

78 p completed follow-up (72±12 yo, 53% females). AF was diagnosed in 27 (34%) p: 22/78 (28%) in the first monitoring and 5/43 (12%) in the second one. para-AF was diagnosed in 22/51 (43%) non-AF p. Other arrhythmias: sustained (>30 s) focal atrial tachycardia documented in 4/51 (8%) non-AF p, AVNRT in 1/51 (2%) non-AF p, advanced AV block in 1/78 (1%) p. Worse left atrial mechanical properties were demonstrated in p with para-AF compared to non-AF p (reservoir strain 22.2±9.8 vs 32.8±12, p=0.004; conduit strain -9.6±4.8 vs -14.4±9, p=0.008; contractile strain 12.6±4.8 vs 17.9±7.8, p=0.025), without significative differences compared to AF p. There were three stroke recurrences (3.8%), 2/3 in para-AF p.

Conclusion

In this preliminary analysis, patients with cryptogenic stroke presented AF in 34% and para-AF in 28%. Para-AF patients show significative atrial dysfunction in echocardiography and more stroke recurrences. A longer follow-up is required to confirm these findings.

Validation of the peak frequency of bipolar electrograms for detection of residual conduction in atrial scar tissue

Funding Acknowledgements

Type of funding sources: Private company. Main funding source(s): Abbott

Background

Activation and voltage (Bi-V) maps (Panel A) based on conventional bipolar electrograms (EGMs) are influenced by both near-field (NF) and far-field (FF) EGM components. This represents a limitation in the accurate detection of residual conduction within regions of scar. Peak frequency (PF) EGM analysis may better distinguish NF from FF activation vs conventional detection methods. (Panels B & C)

Purpose

1. To validate the use of PF to detect residual conduction in a well-defined model of narrow isthmus of conduction such as subacute pulmonary vein (PV) reconnection following atrial fibrillation ablation. 2. To compare discrimination value of PF and conventional Bi-V to detect such isthmuses.

Methods

Bi-V and activation maps were acquired during redo PV isolation (PVI) procedures using a rectangular 16-pole catheter (HD-Grid). LA-PV conduction was assessed during coronary sinus (CS) pacing (500ms cycle length). Any conduction gap (GAP) site at which PVI was established using ≤3 focal radiofrequency applications was analyzed. (Panel A) EGMʼs ≤1cm from the site of PVI were classified as GAP (vs EGMʼs ≥1cm - No-Gap). (Panel B)

Results

28 GAPs were found in 12 of 14 consecutive patients in the study. 3,976 EGMʼs (1,547 GAP vs 2,429 No-GAP) were analyzed. GAP regions showed significantly higher PF than No-GAP regions (345 ±135 vs 181±116 Hz, P<0.0001) (Panel E). GAP regions also showed significantly higher BiV than No-GAP regions

(1.86±2.11 mV vs 0.62±1.22 mV, P<0.0001) (Panel D). ROC curves for GAP vs No-GAP discrimination were better for PF (AUC 0.84) than for Bi-V (AUC 0.74) with optimal cutoffs of 240 Hz and 0.2 mV, respectively. (Panel F)

Conclusion

PF better detects residual conduction within an atrial scar region than conventional Bi-V. The PF cutoff value for gap discrimination in the PV antra is 240 Hz.

Systematic identification of low voltage-high frequency electrogram zones at sites of left atrial reentrant tachycardia termination

Funding Acknowledgements

Type of funding sources: Private company. Main funding source(s): Abbott

Background

Localization of the narrow isthmus of conduction of left atrial local and macro reentrant tachycardia (LAMRT) circuits within scar tissue is challenging. (Panel A). Near-field (NF) electrograms are often obscured by and difficult to distinguish from far-field (FF) activation. The peak frequency (PF) associated with bipolar electrograms is a novel parameter which may distinguish between NF and FF signals. (Panel B). However, the potential value of PF for LAMRT ablation has never been evaluated.

Purpose

1) To quantify the percentage of LA surface with low voltage (LV) and NF signals. 2) To study the proportion of LAMRT ablation sites which were located within a LV-NF region or in the vicinity of it (<10 mm away).

Methods

LART bipolar voltage and activation maps were generated with a 16-pole grid catheter (HD-Grid) during tachycardia. (Panels A,B). PF maps were retrospectively computed (Panels C,D). LV zones were defined according to a cutoff <0.3mV. Four different PF cut-off values (>250, >300, >350 and >400 Hz) were assessed in the delineation of overlapping LV-NF regions. (Panel E)

Results

16 consecutive patients with 24 LAMRT’s targeted for ablation were prospectively enrolled. 21/24 LAMRT’s were terminated by radiofrequency application. (Panel F). The LV area represented 47.7±14% of the LA surface. The LV-NF area represented 8.2±6.2%, 5.2±5.4%, 3.4±7.4% and 3.3±4.1% of the LA surface by using 250, 300, 350, and 400 Hz PF cutoffs respectively. There were 2.1±1 (range 0-3), 0.9±0.8(range 0-3), 0.5±0.6 (range 0-2) and 0.5±0.6 (range 0-2) LV-NF areas per patient using 250, 300, 350 and 400 Hz PF cutoffs respectively. At the optimal PF cutoff > 250Hz and voltage < 0.3mV, the site of tachycardia termination by radiofrequency application was found inside of a LV-NF region in 13/21 LAMRTs (sensitivity 68.4%), and within 1cm of a LV-NF region in 19/21 LAMRTs (sensitivity 89.5%) respectively.

Conclusion

1. Left atrial reentry termination sites by radiofrequency application are often within or nearby LV-NF areas as identified by the PF and voltage analysis of bipolar electrograms. 2. Beyond conventional substrate mapping, the systematic identification of high frequency activity within the low voltage zone holds promise for rapid identification of isthmus conduction critical to LAMRTs.

Performance-based risk-sharing arrangements for devices and procedures in cardiac electrophysiology: an innovative perspective

There is an increasing pressure on demonstrating the value of medical interventions and medical technologies resulting in the proposal of new approaches for implementation in the daily practice of innovative treatments that might carry a substantial cost. While originally mainly adopted by pharmaceutical companies, in recent years medical technology companies have initiated novel value-based arrangements for using medical devices, in the form of 'outcomes-based contracts', 'performance-based contracts', or 'risk-sharing agreements'. These are all characterized by linking coverage, reimbursement, or payment for the innovative treatment to the attainment of pre-specified clinical outcomes. Risk-sharing agreements have been promoted also in the field of electrophysiology and offer the possibility to demonstrate the value of specific innovative technologies proposed in this rapidly advancing field, while relieving hospitals from taking on the whole financial risk themselves. Physicians deeply involved in the field of devices and technologies for arrhythmia management and invasive electrophysiology need to be prepared for involvement as stakeholders. This may imply engagement in the evaluation of risk-sharing agreements and specifically, in the process of assessment of technology performances or patient outcomes. Scientific Associations may have an important role in promoting the basis for value-based assessments, in promoting educational initiatives to help assess the determinants of the learning curve for innovative treatments, and in promoting large-scale registries for a precise assessment of patient outcomes and of specific technologies' performance.

Cardiac arrhythmias in COVID-19: Mechanisms, outcomes and the potential role of proarrhythmia

Funding Acknowledgements

Type of funding sources: None.

Cardiac arrhythmia seems to be a risk factor for mortality in coronavirus disease 2019 (COVID-19). However, the mechanisms, risk factors and outcomes of new arrhythmic events (NAEs) in this disease are unclear.

Methods

All patients with confirmed COVID-19 were retrospectively included in this single centre study. Patients who were alive and admitted <30 days before the database lock were excluded.

Results

3416 consecutive patients were reviewed and 1476 finally enrolled (65.9 ± 20.9 years, 57.3% male). 76 (5.1%) patients had NAEs. Most of them were new atrial fibrillation episodes (48 patients, 3.2%), mostly seen in patients with no previous arrhythmia (38 patients, 79.2%). Atrial flutter (AFL) accounted for 20% of all NAEs. Ventricular arrhythmias were seen in 9 (0.6%) patients. Multivariable analysis showed that prior AFL, heart failure, dyslipidaemia, lopinavir/ritonavir, and combined hydroxychloroquine and azithromycin were independently associated with NAEs. 66 (86.8%) patients with NAEs died. The Kaplan-Meier analysis showed a lower survival of patients with NAEs (P < 0.001). Eight out of 9 (88.9%) and 41 out of 48 (85.4%) patients with ventricular arrhythmias and atrial fibrillation respectively died. Older age, male gender and NAEs were independently associated with death. NAEs and other outcomes, such as heart failure, thromboembolism, and bleeding independently predicted death.

Conclusions

NAEs are relatively uncommon in COVID-19 patients and mainly have an atrial mechanism. AFL is particularly frequent in this disease. The use of hydroxychloroquine, azithromycin and lopinavir/ritonavir, is associated with them, especially when used in combination. NAEs are independently and strongly associated with death.

Characterization of conduction gaps at the pulmonary vein antra by omnipolar voltage mapping

Funding Acknowledgements

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Abbott provided some software to perform special maps

Introduction

Voltage mapping of atrial tissue may be influenced by the direction of the activation front. Omnipolar electrograms may result in better characterization of the atrial tissue. However, little is known about characterization of the pulmonary vein (PV) antra with omnipolar mapping in patients with recurrent atrial fibrillation (AF) following PV isolation (PVI). 

Purpose

To study differences in voltage between regions with (Gap) and without (No-Gap) conduction recurrence at the PV antra by both omnipolar and conventional bipolar mapping in redo PVI procedures.

Methods

Single centre prospective study  of consecutive patients who underwent a redo PVI procedure for AF ablation. Activation and voltage bipolar maps were developed on a electroanatomical system (Ensite Precision) by a steerable catheter with a 16 grid-patterned electrode configuration (HD-Grid) during coronary sinus pacing at both 500 and 300 ms.  Precise location of conduction gaps in the PV antra was attempted by atrial and PV pacing. Only conduction gaps that were ablated by ≤3 focal radiofrequency applications were included in the analysis. Electrograms recorded within 1 cm at both sides of the RF application site were considered related to the gap region. Off-line omnipolar voltage maps were developed with a dedicated experimental software after the procedure .

Results

11 patients were included in the study and 18 gaps were found in 9 patients. 6762 (2688 Gap and 4074 No-Gap)  electrograms were analyzed. Compared with No-Gap PV regions, Gap regions showed significantly (P &lt; 0.0001) higher voltages by omnipolar mapping (0.3 ± 0.6 mV vs 1.1 ± 1.4 mV)  and by absolute (0.2 ± 0.5 mV vs 0.8 ± 1.2 mV),  grid-along (0.3 ± 0.5 mV vs 0.8 ± 1.2 mV) and grid-across  (0.3 ± 0.5 mV vs 0.8 ± 1.1 mV) bipolar mapping.  Omnipolar mapping resulted in higher voltage electrograms when compared with absolute bipole, longitudinal and horizontal bipolar electrograms (P &lt; 0.0001). ROC curves (figure) to differentiate between Gap and No-Gap regions were slightly better for omnipolar electrograms (AUC 0.79) than for conventional grid -along or grid-across bipolar mapping (AUC 0.76 and 0.77) with the best discrimination value of 0.3 and 0.2 mV respectively.  Conclusion: There are significant differences in voltage between conduction Gap and No-Gap regions at the PV antra which are more apparent with omnipolar than with conventional bipolar mapping. 0.3 mV and 0.2 mV values are the best to differentiate between PV conduction Gap and No-Gap regions with ominpolar and conventional mapping respectively

Incidence and type of arrhythmias recorded by one-month continuous ECG monitoring in stroke patients

Funding Acknowledgements

Type of funding sources: None.

BACKGROUND

The incidence of atrial fibrillation (AF) following stroke has been studied with implantable loop recorders.  However, these devices do not record short lasting AF episodes (&lt;30-120 seconds [s]). In addition, the incidence and type of other clinically relevant arrhythmias is poorly understood in this clinical setting.

PURPOSE

To evaluate the incidence, type and clinical relevance of arrhythmias detected by one-month continuous ECG monitoring in patients after cryptogenic stroke.

MATERIAL AND METHODS

Consecutive patients (p) with stroke and no previous AF or other cardioembolic or atheroembolic causes were prospectively enrolled in the study. An external wearable 2-lead ECG monitoring system (NUUBO) was used for 30 days (d) in all of them after the acute phase of the stroke. In the absence of documented AF, a parafibrillatory status was defined as &gt;3000 atrial ectopic beats/d or &gt;2 "micro AF" episodes (fibrillatory burst &lt;30 s)/d or ≥1 episode of "micro AF" &gt;14 s.

RESULTS

130 p. were included in the study (age 73 ± 12, 57% males, 19% previous stroke, 7% ischemic cardiopathy, CHA2DSVA2Sc pre-stroke 3.1 ± 1.7).  3 were withdrawn from the study due to inadequate use (recording time &lt;14 d) and 1 due to stroke during SARS-CoV2 infection. Total recording time was 28 ± 3 d, total analyzable ECG time was 23 ± 5 d. ECG monitoring was repeated in 12 (9.5%) p due to poor ECG quality in 6 p or high suspicion of AF despite an initial negative result in 6 p.  AF &gt;30 s was detected in a total of 27 (21.4%) p, average AF duration was 52 hours (range 30 s-22 d). AF &gt;30s was detected in 2 (17%) p with repeated monitoring. All these patients were placed on anticoagulation. Sustained paroxysmal supraventricular tachycardia (SVT) was documented in 4 (4.4%) p without AF. All episodes of AF and SVT were asymptomatic. Mobitz I second degree AV block in 4 (3.2%) p. 3 (2.4%) p had a pacemaker implanted: 2 for severe sinus dysfunction and 1 for AV block. High-density ventricular ectopy (&gt;3000/d) was present in 7 (6%) p and ≥1 episode of non-sustained ventricular tachycardia was detected in 26 (21%) p. A parafibrillatory status was identified in 27 (21%) p with no AF &gt;30 s. At 1-year follow up 4/22 (18%) of patients with parafibrillatory status and 3/59 (5%) without parafibrillatory status suffered a new stroke (p = 0.08).

CONCLUSIONS

AF and other potentially relevant arrhythmias are frequent after stroke and easily detectable with one-month non-invasive continuous ECG monitoring. Patients with a parafibrillatory status could benefit from longer monitoring time to detect AF.

Antiarrhythmic Medication for Atrial Fibrillation (AIM-AF) study: A physician survey of antiarrhythmic drug (AAD) treatment practices and guideline adherence in the EU and USA

Funding Acknowledgements

Type of funding sources: Private company. Main funding source(s): Sanofi

Introduction

The 2020 European Society of Cardiology and the 2019 USA (AHA/ACC/HRS) guidelines recommend the use of AADs for rhythm control in patients with symptomatic AF. This study sought to understand AAD treatment practices and adherence to guidelines across the EU and the USA.

Method

An online physician survey of cardiologists, cardiac electrophysiologists and interventional electrophysiologists (N = 569) was conducted in the USA, Germany, Italy and the UK. All respondents were actively treating ≥10 AF patients who received drug therapy and/or who had received or were referred for ablation. This extensively detailed survey explored questions on physician demographics, AF types, and drug treatment and ablation practices.

Results: Of the responses obtained

(1) Amiodarone was used frequently across co-morbidity categories (highest use in those with heart failure with reduced left ventricular ejection fraction [LVEF] [80%]), including in those in which it is not indicated for initial therapy (minimal or no structural heart disease: 26%). Other deviations from guideline recommendations, include: class 1C drugs were used with structural heart disease, including coronary artery disease (CAD) (average class 1C use in CAD-related comorbidities: 6%); sotalol was used with renal dysfunction (22%); and drugs such as sotalol and dofetilide were initiated out of hospital (56% and 17% of respondents, respectively). (2) Nonetheless, a majority of respondents (53%) considered guidelines as the most important non-patient factor in influencing their choice of AF management. (3) Rhythm control was selected more frequently as primary therapy for paroxysmal AF (PAF) (59% of patients) while rate control was used more often for persistent AF (53%). (4) For PAF, AADs were preferred as 1st line more often than ablation, especially if PAF was infrequent and mildly symptomatic (59% of respondents) while ablation was preferred more if frequent symptomatic PAF and for recurrent persistent AF. (5) Rhythm control (AAD or ablation) was chosen in notable numbers for asymptomatic AF and subclinical AF (AADs: 36% and 37%, respectively; ablation: 9% and 14%, respectively). (6) AAD use for those with a first or recurrent episodes of symptomatic AF was 60% or 47%, respectively. (7) Efficacy and safety were chosen as the most important considerations for choice of specific rhythm control therapy (49% and 33%, respectively), and reduction of mortality and cardiovascular hospitalisation (23%) were as important as maintaining sinus rhythm (26%) for rhythm therapy goals.

Conclusions

Although surveyed clinicians consider guidelines important, deviations in patient types and treatments chosen that compromise safety or were not indicated were common. Findings suggest a lack of understanding of the pharmacology and safe use of AADs, highlighting an important need for further education. Abstract Figure.

1246High-power and short-duration radiofrequency ablation for atrial fibrillation: feasibility, safety and one-year results

Funding Acknowledgements

SEC-Bayer research project 2018, Spanish Society of Cardiology. Research project 2018, FIS, Insituto de Salud Carlos III.

OnBehalf

none

Pulmonary vein (PV) isolation (PVI) by point-by-point radiofrequency application (PPRF) results in longer procedures than cryoablation. In addition, it is associated with more oesophageal lesions. The aim of this study was to evaluate the feasibility, safety and 1-year efficacy of PVI by high power short duration (HPSD) PPRF in patients with atrial fibrillation (AF).

METHODS

PPRF around the PV was performed in 125 patients (P) distributed in two groups. Conventional PPRF with 30W/≤30 s under luminal oesophageal temperature monitoring was performed in the first 47 P (Group 1). 68 P were enrolled in the HPSD (Group 2). Power was set to 50 W and delivered to reach a predefined lesion index value (LSI≥5 or AI≥350) in the first 18 P (Group 2A). 30 P underwent PPRF with 60 W for 7-10 s (Group 2B) and the last 30 P underwent PPRF with 70W for 9 s (Group 2C). Oesophageal endoscopy was performed after ablation in all P.

RESULTS

17 (36%) P in Group 1 and 30 (38%) in Group 2 had persistent AF. PVI of all targeted veins was achieved in 96% and 100% of P in both groups (p = 0,6).  Total RF time was 30 [27-42], 25[ 20-29], 16 [14-20] and 13 [11-16] in Groups 1, 2A, 2B and 2C respectively (p &lt; 0.01). RF duration per target lesions was 12[9-17], 9[8-9] and 9[9-9] s in Groups 2A, 2B and 2C respectively (p &lt; 0.001). First-pass PVI was achieved in 35% 56%, 57% and 85% of left PV circles (p &lt; 0.001) and in 46%, 56%, 60% and 82% of right PV circles (p = 0.04) in groups 30W, 50W, 60W and 70W respectively. Reconnections occurred in 8% of PV circles in Group 1 and in 6.5% of PV circles in Group 2 (p = 0.8).  Dormant conduction was tested with adenosine in Groups 2B and 2C and the incidence was 30% and 25% of PV circles respectively (p = 0.31). The carina was the most frequent location of conduction gaps, reconnections and dormant conduction in all groups. The incidence of oesophageal lesions was 28% in Group 1, 22% in Group 2A and 0% in groups 2B and 2C (p &lt; 0.002). The 1-year efficacy (freedom from any atrial tachycardia recurrences &gt;30 s) was 59% in Group 1, 88% in group 2A, 77% in group 2B and 87% in group 2C (p = 0.019).

CONCLUSIONS

PVI by HPSD PPRF is feasible and results in high 1-year efficacy in P with AF. This approach appears safe and associated with low incidence of oesophageal damage especially when short application time and 60 or 70W are used. However, this latter power setting is associated with slightly better 1-year efficacy than HPSD PPRF using 60W.

Abstract Figure. Recurrences of atrial arrhythmias (&gt;30 s

Initiating renal replacement therapy through incremental haemodialysis: Protocol for a randomized multicentre clinical trial

Background

Thrice-weekly haemodialysis is the usual dose when starting renal replacement therapy; however, this schedule is no longer appropriate since it does not consider residual renal function. Several reports have suggested the potential benefit of beginning haemodialysis less frequently and incrementally increasing the dose as the residual renal function decreases. However, all the data published so far are from observational studies. Thus, this clinical trial avoids any potential selection bias and will assess the possible benefits that have been observed in observational studies.

Methods/design

This report describes the study protocol of a randomized prospective multi-centre open-label clinical trial to evaluate whether starting renal replacement therapy with twice-weekly haemodialysis sessions preserves residual renal function better than the standard thrice-weekly regimen. We also explore other clinical parameters, such as concentrations of uremic toxins, dialysis doses, control of anaemia, removal of medium-weight uremic toxins, nutritional status, quality of life, hospital admissions and mortality. Only incident haemodialysis patients who can maintain a urea clearance rate KrU ≥ 2.5 mL/min/1.73 m² are eligible. Patient recruitment began on 1 January 2017 and will last for 2 years or until the required sample size has been recruited to ensure the established statistical power has been reached. The minimum follow-up period will be 1 year. Anuric patients with acute renal failure and patients who return to haemodialysis after a kidney transplant failure are excluded. It has been calculated that 44 patients should be recruited into each group to achieve a power of 80% in a two-sided comparison of means with a usual significance level of 0.05. A time-to-event analysis will estimate the probability of kidney function survival in both groups using the Kaplan–Meier method. Survival curves will be compared with log-rank tests. This survival analysis will be complemented with a proportional hazard model to estimate the hazard ratio of kidney function survival adjusted for any confounding factors. Analyses will be carried out in accordance with the intention-to-treat principle.

Discussion

The incremental initiation of dialysis may preserve residual renal function better than the conventional treatment, with similar or higher survival rates, as reported by observational studies. To our knowledge, this is the first clinical trial to evaluate whether initiating renal replacement therapy with twice-weekly haemodialysis sessions preserves residual renal function better than beginning with the standard thrice-weekly regimen.

Trial registration

ClinicalTrials.gov, NCT03302546. Registered on 5 October 2017.

P1013Biannular atrial flutter: clinical and electrophysiological characterization by activation and entrainment

Introduction

re-entry mechanisms around mitral and tricuspid annuli are frequent causes of left and right atrial flutter (AFt) respectively in patients with ipsilateral atrial pathology. However, clinical and electrophysiological characteristics of other types of atrial re-entries that could involve both AV annuli are less known.

Purpose

characterize biannular atrial flutters.

Methods

4 patients with AFt were submitted for ablation (aged 30, 31, 58 and 61 yo; 2 females). All had a cardiac congenital disease with a prior surgical procedure: 3 atrial septal defects (ASD) with surgical repair and 1 with transposition of the great arteries (TGA) with Senning repair. The AFt had a cycle length (CL) of 290, 315, 330 y 340 ms respectively and 1:1 AV conduction in 3 of them. For the electrophysiological study, a multipolar catheter (20 or 24 poles) was placed in the right atrium (RA) in every patient, showing counterclockwise and clockwise activation in 1 and 3 patients, respectively. Coronary sinus (CS) activation was proximal to distal in one patient and distal to proximal in the other 2. No CS activation could be obtained in the patient with Senning repair.

Results

each AFt was mapped by entrainment from different sites of the RA, showing post-pacing intervals (PPI) similar to the CL of the AFt around the tricuspid annulus in all of them and also from proximal and distal CS in the 3 patients with ASD. Access to the native left atrium (LA) was achieved in the patient with Senning repair, showing PPIs around the mitral annulus that were similar to the LC of the tachycardia. In 2 patients the attempt to get to the LA through the interatrial septum (IAS) could not be achieved and was unattempted in the other one. Recordings and PPIs of the LA roof were obtained from the right branch of the pulmonary artery in 2 patients. Counterclockwise AFt and clockwise AFt by single biannular perimitrotricuspid rotation in 1 and 3 patients respectively. The AFt was ended and no reinduction was possible after radiofrequency application that achieved cavotricuspid isthmus block in all of the patients.

Conclusions

reentry around both AV annuli is possible as a single loop, counterclockwise or clockwise, of simultaneous rotation as a clinical mechanism of Aft. This type of AFt seems to be associated to absence or severe damage in the IAS.

6122Pulmonary vein isolation by different setting of high-power short-duration radiofrequency application: feasibility, short term efficacy and safety in patients with atrial fibrillation

Aims

Pulmonary vein (PV) isolation (PVI) by point-by-point radiofrequency application (PPRF) results in longer procedures than cryoballoon ablation. In addition, it is associated with more esophageal lesions. The aim of this study was to evaluate the feasibility and safety of PVI by high power short duration (HPSD) PPRF in patients with atrial fibrillation.

Methods

PPRF around the PVs was done in 125 consecutive patients distributed in two chronologically successive groups. Conventional PPRF with 30W for ≤30 s under luminal esophageal temperature monitoring was performed in the first 47 patients (Group 1). 68 patients were enrolled in the HPSD (Group 2). Power was set to 50 W and delivered to reach a predefined lesion index value (LSI ≥5 or Abl-I ≥350) in the first 18 patients (Group 2A). 30 patients underwent PPRF with 60W for 7–10 s (Group 2B) and the last 30 patients underwent PPRF with 70W for 9 s (Group 2C). Esophageal endoscopy was performed after ablation in all patients.

Results

PVI of all targeted veins was achieved in 96% and 100% of patients of groups 1 and 2 respectively (p=0.6). Total RF time was 30 [27–43], 25 [20–29], 16 [14–20] and 14 [11–16] min in groups 1, 2A and 2B and 2C respectively (p<0.001). RF was delivered for 12 [9–17] s vs 9 [8–9]s vs 9 [8–9] per application in groups 2 A, 2B and 2C respectively (p<0.001). Total number of RFa to completely isolate all PV was 105 [90–126] in group 2A, 113 [90–135] in group 2B and 94 [79–112] in group 2C (p=0.12).

First-pass PVI was achieved in 56%, 57% and 85% of left PV (p=0.038) and in 56%, 60% and 82% of right PV (p=0.13) in groups 50W, 60W and 70W respectively. The carina was the most frequent location of persistent conduction when first-pass failed. Reconnections occurred in 6%, 3% and 11% of left PV (p=0.6) and in 6%, 7% and 4% (p=0.63) of right PV in groups 50W, 60W and 70W respectively. Adenosine test was systematically used in groups 60W and 70W: the incidence of dormant conduction was 23% and 22% (p=0.9) in left PV and 20% and 22% (p=0.8) in right PV respectively.

The incidence of esophageal lesions was 28% in Group 1, 2% in Group 2A, and 0% in groups 2B and 2C (p<0.001). No other intraprocedural complications occurred in the high-power group.

Total RF time

Conclusions

PVI is feasible with HPSD PPRF in most patients using shorter total RF times. This approach appears associated with very low incidence esophageal damage than the conventional one, especially when 60W/70W and shorter application time are used.

Acknowledgement/Funding

Grant of the Spanish Society of Cardiology

Revolving thrombus within the left atrium at atrial fibrillation ablation

A 68-year-old man was referred for pulmonary vein (PV) isolation. Access to the left atrium was obtained via a single transseptal puncture. A heparin bolus was given immediately after puncture. Angiography of the left PV was performed. After the contrast wash-out, a contrasted longitudinal thrombus was shown revolving within the left atrium for several seconds before being expelled through the mitral and aortic valves. It is common practice in these procedures to administer an intravenous bolus of heparin immediately after the transseptal puncture. However, heparin has latency to become effective, and this can result in thromboembolic events.

Inflammatory Asthma Phenotype Discrimination Using an Electronic Nose Breath Analyzer

BACKGROUND AND OBJECTIVE

Patients with persistent asthma have different inflammatory phenotypes. The electronic nose is a new technology capable of distinguishing volatile organic compound (VOC) breath-prints in exhaled breath. The aim of the study was to investigate the capacity of electronic nose breath-print analysis to discriminate between different inflammatory asthma phenotypes (eosinophilic, neutrophilic, paucigranulocytic) determined by induced sputum in patients with persistent asthma.

METHODS

Fifty-two patients with persistent asthma were consecutively included in a cross-sectional proof-of-concept study. Inflammatory asthma phenotypes (eosinophilic, neutrophilic and paucigranulocytic) were recognized by inflammatory cell counts in induced sputum. VOC breath-prints were analyzed using the electronic nose Cyranose 320 and assessed by discriminant analysis on principal component reduction, resulting in cross-validated accuracy values. Receiver operating characteristic (ROC) curves were calculated.

RESULTS

VOC breath-prints were different in eosinophilic asthmatics compared with both neutrophilic asthmatics (accuracy 73%; P=.008; area under ROC, 0.92) and paucigranulocytic asthmatics (accuracy 74%; P=.004; area under ROC, 0.79). Likewise, neutrophilic and paucigranulocytic breath-prints were also different (accuracy 89%; P=.001; area under ROC, 0.88).

CONCLUSION

An electronic nose can discriminate inflammatory phenotypes in patients with persistent asthma in a regular clinical setting. ClinicalTrials.gov identifier: NCT02026336.

[Recurrence of p-ANCA positive vasculitis with lung hemorrhage in a patient on hemodialysis]

Relapses of p-ANCA vasculitis during chronic dialysis treatment are infrequent. We report a patient with a pulmonary-renal syndrome and p-ANCA vasculitis who relapsed one year after starting hemodialysis treatment. Treatment with steroids and cyclosphosphamide successfully controlled the relapse, though cyclophosphamide had to be discontinued because of leucopenia. Clinical features of renal vasculitis, relapse after dialysis, the usefulness of ANCA titles as possible predictors and therapeutic options are discussed.

[The figure of Chief of Residents in the Residencing training: establishment and development in a Spanish hospital]

Training qualified medical specialists is one of the great supports of the Spanish health care system. The teaching structure of the hospital is essential for the correct development of this training. The figure of the chief resident (CR) is widely developed in the USA and Canada, but not in our country. Including this figure in the teaching organigram of our hospital has meant one more advance in the search for improving our teaching capacity. In the following, we explain our experience during the introduction and later development of the figure of CR, stressing its theoretical functions, the notification mechanism, constitution of the Residents' Committee and later development of activities and tasks conducted. After three years, our experience is favorable, subject to modifications, but adaptable to the idiosyncrasy of each site.

[Control of the dialysis dose by ionic dialysance and bioimpedance]

INTRODUCTION

The ionic dialysance monitor allows an automated measure of Kt in each dialysis session. Bioelectrical impedance analysis (BIA) determines the total body water which it is equivalent to the urea volume of distribution (V). If the Kt, determined by ionic dialysance, is divided by the V, estimated by bioelectrical impedance, a Kt/V at the end of dialysis session (Kt/VDiBi) is obtained.

AIM OF THE STUDY

To evaluate the agreement between the Kt/VDiBi and the Kt/V obtained by two simplified formulas: the monocompartimental (Kt/Vm) and the equilibrated (Kt/Ve) Daugirdas equations.

METHODS

The Kt/VDiBi, the Kt/Vm and the Kt/Ve were determined in 38 hemodialysis patients (27 males and 11 females) in the same hemodialysis session. The patients were on dialysis three times a week for 3.5 to 4 hours. The V was determined by monofrequency bioelectrical impedance (50 kHz) at the end of the dialysis session.

RESULTS

The Kt/VDiBi, Kt/Vm and Kt/Ve were 1.29+/-0.26, 1.54+/-0.29 and 1.36+/-0.25, respectively (p<0.001 between the Kt/VDiBi and the KtVm, and p<0.001 between the KtV/DiBi and the Kt/Ve). The intraclass correlation coefficient showed better concordance between the KtV/DiBi and the Kt/Ve (coefficient 0.88) than between the Kt/VDiBi and the KtVm (coefficient 0.65). The relative difference of the Kt/VDiBi was 8.3+/-6.4% with respect to the Kt/Ve and 18.4+/-7.8 % with respect to the Kt/Vm (p<0.001). The relative difference between the Kt/VDiBi and the Kt/Ve was lower than 15% in the 84% of the patients and lower than 10% in the 64% of the patients.

CONCLUSIONS

If the V obtained by bioelectrical impedance analysis is included in the ionic dialysance monitor, we can obtain a Kt/V for each patient in real time, which is similar to the equilibrated Kt/V obtained from the Daugirdas equation.

[The Cockcroft-Gault equation is better than MDRD equation to estimate the glomerular filtration rate in patients with advanced chronic renal failure]

ABSTRACT The aim of this study was to compare the accuracy of three kidney function estimating equations: classic Cockcroft-Gault (classic CG), corrected Cockcroft-Gault (corrected CG) and simplified Modification of Diet in Renal Disease (MDRD), in patients with advanced chronic renal failure. The study was made in 84 nondialyzed patients with chronic renal disease in stage 4 or 5. The glomerular filtration rate was measured on a 24-hour urine collection as the arithmetic mean of the urea and creatinine clearances (CUrCr). In each patient, the difference between each estimating equation and the measured glomerular filtration rate was calculated. The absolute difference expressed as a percentage of the measured glomerular filtration rate indicates the intermethod variability. In the total group the glomerular filtration rate measured as the CUrCr was de 13,5+/-5,1 ml/min/1.73 m(2); and the results of the estimating equations were: classic CG 14,2+/-5 (p<0,05); corrected CG 12+/-4,2 (p<0,01) and MDRD : 12,1+/-4,8 ml/min/1.73 m(2) (p<0,01). The variability of the estimating equations was 15,2+/-12,2%, 17,1+/-13,4 % and 19,3+/-13,3% (p<0,05), for classic CG, corrected CG and MDRD respectively. The percent of estimates falling within 30% above o below the measured glomerular filtration rate was 90% for CG classic, 87% for corrected CG and 79% for MDRD. The intraclass correlation coefficients respect to CUrCr were 0,86 for classic CG, 0,81 for corrected CG and 0,77 for MDRD. The MDRD variability, but not classic CG variability or corrected CG variability, showed a positive correlation with the glomerular filtration rate (r=0,25, p<0,05). In patients with chronic renal disease in stage 5, the variability of the different estimating equations was similar. We conclude that in our population with advanced chronic renal failure the classic CG equation is more accurate than the MDRD equation. Corrected CG equation has not any advantage respect to classic CG equation.

[Temperature dialysate and hemodialysis tolerance]

In this study, the effect of dialysate temperature on hemodynamic stability, patients' perception of dialysis discomfort and postdialysis fatigue were assessed. Thirty-one patients of the morning shift were eligible to participate in the study. Three patients refused. Patients were assessed during 6 dialysis sessions: in three sessions the dialysate temperature was normal (37 degrees C) and in other three sessions the dialysate temperature was low (35.5 degrees C). To evaluate the symptoms along the dialysis procedure and the postdialysis fatigue, specific scale questionnaires were administered in each dialysis session and respective scores were elaborated. Low temperature dialysate was associated with higher postdialysis systolic blood pressure (122 +/- 24 vs. 126 +/- 27 mmHg, p < 0.05), and lower postdialysis heart rate (82 +/- 13 vs. 78 +/- 9 beats/min, p < 0.05) with the same ultrafiltration rate. Dialysis symptoms score and postdialysis fatigue score were better with the low dialysate temperature (0.7 +/- 0.9 vs. 0.4 +/- 1 vs. p < 0.05, and 1.3 +/- 1 vs. 1 +/- 0.9 p < 0.05, respectively). Furthermore, low temperature dialysate shortened the post-dialysis fatigue period (5.4 +/- 6.3 vs. 3.1 +/- 3.3 vs. hours, p < 0.05). The clinical improvement experimented with the low temperature dialysate was not universal. A beneficial effect was exclusively observed in the patients with higher dialysis symptoms and postdialysis fatigue scores or having more than one episode of hypotension in a week. The patients were asked about their temperature preference, 7 patients (23%) request a dialysate at 37 degrees C, 19 patients (61%) prefered to be dialysed with the low temperature dialysate, and 5 patients (16%) were indifferent. The later two groups of the patients continued with the low temperature dialysate during other 4 weeks. At the end of that period, the clinical improvement remained unchanged. In summary, low temperature dialysate is particularly beneficial for highly symptomatic patients.

[Urea distribution volume calculated by ionic dialysance]

BACKGROUND

Direct dialysis quantification is considered the gold standard for determining urea distribution volume, but it is impractical for routine use. So, urea distribution volume in hemodialysis patients is usually estimated from anthropometric equations. Ionic dialysance allows to calculate the urea distribution volume dividing the Kt obtained by ionic dialysance by the Kt/V obtained by a simplified formula. The aim of the present work was to analyse the concordance between the ionic dialysance and the direct dialysis quantification methods to estimate de urea distribution volume.

MATERIAL AND METHODS

In 15 hemodialysis patients (10 males and 5 females), we have estimated the urea distribution volume by the direct dialysis quantification (Vurea), by the anthropometrics equations of Watson (VWatson) and Chertow (VChertow) and by the ionic dialysance method (VDI). To obtain VDI we have used two simplified Kt/V formulas: the monocompartimental and the equilibrated Daugirdas equations (VDIm and VDIe respectively). The intermethod variability was assessed by the relative difference (absolute difference between VUrea and the other methods, divided by the mean).

RESULTS

VUrea (26,2 L) was statistically different from theVDIe (30,6 L, p < 0.01), VWatson 35.2 L (p < 0.001) and VChertow (38 L, p < 0.001). VDIm was 26.3 L (p = ns). VUrea represents the 42% of the body weight for the males (range 36 to 49%) and the 33% of the body weight for the female (range 28 to 38%). The intermethod variability was high for the VDIe (21.6%), VWatson (37.4%) and VChertow (48. 1%), but it was low for the VDIm (9.9%).

CONCLUSIONS

Urea distribution volume calculated by the ionic dialysance method using the monocompartimental Daugirdas Kt/V equation has an acceptable agreement with the urea distribution volume calculated by the direct dialysis quantification. Anthropometry-based equations overestimate the urea distribution volume in hemodialysis patients.

Mechanisms underlying ventricular arrhythmias in idiopathic dilated cardiomyopathy: implications for management

Ventricular arrhythmias (VA) have been associated with mortality in idiopathic dilated cardiomyopathy (IDCM). All 3 main mechanisms of arrhythmogenesis - reentry, trigger activity, and automatism - have been implicated. Arrhythmogenic substrates in IDCM favor these mechanisms and are often potentiated by electrolyte imbalance secondary to diuretic treatment, by antiarrhythmic drugs, or by bradycardia, leading to polymorphic ventricular tachycardia (VT). Myocardial macroreentry is the mechanism most frequently responsible for monomorphic VT in IDCM; however, focal activation and His-Purkinje macroreentry are often responsible and, especially in the latter case, are frequently unrecognized. Clinical suspicion and final recognition by electrophysiologic testing have important therapeutic consequences, because both focal activation and His-Purkinje macroreentry can be treated effectively by catheter ablation. On the other hand, the frequent recurrences of myocardial macroreentrant VT after ablation require this therapy to be used in combination with drugs or an implantable cardioverter defibrillator (ICD). beta-Adrenoceptor antagonists (beta-blockers) have a beneficial effect for primary prevention of VA in IDCM. Type III antiarrhythmics have a neutral effect on mortality and type I antiarrhythmics should be avoided. Treatment of nonsustained VT in IDCM is controversial because it often presents without symptoms and is linked more to overall mortality than to arrhythmic mortality. Empiric treatment with amiodarone or electrophysiologically guided sotalol are preferred to the use of other drugs for secondary prevention of sustained VA. ICDs should be implanted in patients who have been resuscitated from cardiac arrest due to VA, or in those with poorly tolerated VT and severe left ventricular dysfunction. Empiric treatment with amiodarone or electrophysiologically guided class III antiarrhythmics may also be alternatives for patients with IDCM and no severe left ventricular dysfunction, especially if VT is well tolerated.

[Therapy with interferon plus ribavirin in hemodialysis patient with PCR-positive viral hepatitis C]

Traditionally, the treatment of viral hepatitis C (positive Polymerase Chain Reaction -PCR-) was with Interferon. A combination of Interferon plus Ribavirin has been producing better results in last years. Currently, Ribavirin is not indicated for patients with Chronic Kidney Disease because of a high risk of severe anaemia. In a few cases, this treatment is producing good results with previous dose adjustment. We show a case of a 28-year-old man with Chronic Kidney Disease on treatment with periodical hemodialysis and chronic hepatopathy HCV Positive RNA HCV (> 1,000,000 copies/ml) and persistent transaminase elevation. Before kidney transplantation, we decided to use Interferon (3,000,000 IU/48 hours) and Ribavirin (200 mg/24 hours) treatment. After 15 days, we saw normal transaminase values and HCV RNA was negative. The patient required temporary suspension of Ribavirin and two red blood cell transfusions due to severe anaemia. Ribavirin was reintroduced 200 mg/48 h posthemodialysis. The patient did not present any complication again, and could be treated for 14 months. After next 11 months of evolution the patient has normal rates of liver function and negative HCV RNA values.

[Membranous nephropathy associated to autoimmune thyroiditis, chronic pancreatitis and suprarrenal insufficiency]

A 33 year old female was admitted to the hospital to study aedema and bocio, A nephrotic syndrome was diagnosed and the renal biopsy demonstrated membranous glomerulonephritis, stage II. She was also diagnosed of Hashimoto's autoinmmune thyroiditis: TSH (41.5 uUl/ml), T4 (0.07 ng/dl), antithyroglobuline (1/2560) and antimicrosome (1/6400). Four year latter she was diagnosed of autoinmmune pancreatitis, without evidence of diabetes mellitus or exocrine pancreatic insufficiency. Eight years latter she was diagnosed of primary autoimmune suprarrenal insufficiency: basal cortisol: 2.7 mcg/dl, post ACTH estimulated cortisol: 5.6 mcg/dl, antinuclear antibody (1/160) and antiparietal (1/320). We present a pluriglandular autoimmune syndrome with membranous glomerulonephritis, thyroiditis, pancreatitis and suprarrenal insufficiency. To the best of our knowledge this complex syndrome has not been previously described.

[Ionic dialysance to control the dose of dialysis. One year experience]

The Diascan equipment (Hospal) measures ionic dialysane which it derives the K and the Kt. If we divide the Kt obtained with Diascan between the Kt/V obtained by a simplified formula, it result a value of V for every patient. Entering this V in the Diascan software we can obtain a Kt/V (Diascan Kt/V), similar in theory to the simplified Kt/V. In the year 2002 we have controlled the delivered dialysis in our unit with the Diascan Kt/V. The aim of the present study was to study the agreement between de Diascan Kt/V and the Lowrie Kt/V. During the year 2002, 63 patients have been dialyzed in monitors with Diascan equipment. We calculated the V of each patient by dividing the Kt Diascan between the Lowrie Kt/V in the same dialysis session. The mea of the two consecutive measurements was considered the V value. Throughout the year 2002, 7 agreement studies were realized. The inter-method variability was assessed by the relative difference (absolute difference Diascan Kt/V-Lowrie Kt/V, divided by the average of both tests). A good agreement was considered when the relative difference was equal or lower than 10%. In the 7 agreement studies realized, the mean of the relative difference oscilled between 5.2 and 6.6%, and the percentage of patients with a relative difference equal or lower than 10% oscilled between 83 and 91%. During a month, the Diascan Kt/V was controlled in all dialysis sessions in 41 patients (554 sessions in total). Failure in the lecture of Kt/V Diascan was observed in 41 sessions (7%). A Diascan Kt/V greater than 1 (the minimum delivered dialysis considered in our unit) was obtained in 93% of the valid sessions. 38 of 41 patients had a mean monthly Diascan Kt/V greater than 1. The coefficient of variability of any patient oscilled between 2.1 and 12.4% (mean 5.1%). Diascan Kt/V is good procedure for the monitoring the delivered dialysis without blood sampling or any additional costs.

Decremental atriofascicular accessory pathway with bidirectional conduction: delineation of atrial and ventricular insertion by radiofrequency current application

A 17-year-old girl with a corrected complex congenital heart disease and recurrent episodes of supraventricular tachycardia was referred for catheter ablation. Electrophysiologic studies revealed the presence of an accessory pathway (AP) with bidirectional conduction and decremental properties. We demonstrated a course parallel to the node-His AV conduction system. Transient abolition of the bidirectional conduction through the AP was obtained by radiofrequency application to the ventricular insertion located in the distal right bundle branch and to the atrial insertion, located in the mid-anterior atrial septum. Radiofrequency application at the low anterior atrial septum, above the His bundle, successfully abolished AP conduction without affecting AV nodal conduction. Demonstration of the course and insertions of the AP, its bidirectional decremental conduction properties, and the association with a complex congenital heart disease are exceptional and interesting findings and raise the possibility of an accessory AV node with a parallel conduction pathway to the right bundle branch.

Bundle-branch reentry and the postpacing interval after entrainment by right ventricular apex stimulation: a new approach to elucidate the mechanism of wide-QRS-complex tachycardia with atrioventricular dissociation

BACKGROUND

Diagnosis of bundle-branch reentry ventricular tachycardia (BBR-VT) by the standard approach is challenging, and this may lead to nonrecognition of this tachycardia mechanism. Because the postpacing interval (PPI) after entrainment has been correlated with the distance from the pacing site to the reentrant circuit, BBR-VT entrainment by pacing from the right ventricular apex (RVA) should result in a PPI similar to the tachycardia cycle length (TCL). This factor may differentiate BBR-VT from other mechanisms of wide-QRS-complex tachycardia with AV dissociation, such as myocardial reentrant VT (MR-VT) or AV nodal reentrant tachycardia (AVNRT), in which the circuit is usually located away from the RVA.

METHODS AND RESULTS

Transient entrainment by RVA pacing was attempted in 18 consecutive BBR-VTs and finally achieved in 13. Results were compared with those found in 59 consecutive MR-VTs and 50 consecutive AVNRTs. The mean PPI-TCL difference was significantly (P:<0.0001) shorter in the BBR-VT group (9+/-11 ms) than in the MR-VT (109+/-48 ms) and the AVNRT (150+/-29 ms) groups. No BBR-VT showed a PPI-TCL >30 ms (range -12 to 24 ms). Except for 2 MR-VTs, no MR-VT (range 21 to 211 ms) or AVNRT (range 100 to 215 ms) showed a PPI-TCL <30 ms.

CONCLUSIONS

A PPI-TCL >30 ms, after entrainment by RVA stimulation, makes BBR-VT unlikely. Conversely, a PPI-TCL <30 ms is suggestive of BBR-VT but should lead to further investigation by use of conventional criteria.

Ablation of idiopathic ventricular tachycardia by bipolar radiofrequency current application between the left aortic sinus and the left ventricle

BACKGROUND

Failure to ablate idiopathic ventricular outflow tract tachycardia by radiofrequency current is not uncommon and suggests that non-standard approaches may be required to map and suppress idiopathic ventricular tachyarrhythmias in some patients.

METHODS AND RESULTS

Left and right ventricular activation and pace mapping proved inadequate for radiofrequency application in a patient with idiopathic ventricular outflow tract tachycardia. Presystolic activity was recorded at the left aortic sinus of Valsalva, and the QRS complex recorded at this location during pacing showed few differences compared with that recorded during tachycardia. Radiofrequency current application at this site transiently suppressed the tachycardia. Following new mapping of the left ventricle outflow tract, radiofrequency application just below the aortic valve in close proximity to the previous aortic application site transiently abolished the arrhythmia. Finally, bipolar radiofrequency application between the distal electrode of the aortic catheter and the distal electrode of a second catheter placed in the left ventricular subaortic area permanently suppressed the tachycardia.

CONCLUSION

Bipolar radiofrequency application between the aortic sinus of Valsalva and the left ventricle could be an alternative approach in occasional patients with idiopathic ventricular outflow tract tachycardia resistant to conventional left ventricular and aortic root unipolar radiofrequency application.

[Cardioinhibitory vagal response not related to pain, and induced by radiofrequency application during ablation of right posteroseptal accessory pathway]

Inappropriate sinus tachycardia is the most common arrhythmia induced by radiofrequency energy delivery in the posteroseptal area. It has been suggested that this could be secondary to parasymphathetic nerve injury. We report a patient with extreme sinus bradycardia and PR interval prolongation induced by radiofrequency energy delivered in the coronary sinus ostium area, but not related to any other stimulus. The most probable mechanism of the disorder was transient stimulation of the vagal afferent nerve fibers located in this anatomical area.

[Oblique orientation of the accessory pathway demonstrated by radiofrequency application]

Activation mapping of atrial and ventricular insertion has suggested an oblique orientation of some accessory pathways. However, this aspect has not been demonstrated by radiofrequency application. This report presents two patients with Wolff-Parkinson-White syndrome and an accessory pathway with bidirectional conduction and oblique orientation. The accessory pathway oblique orientation was demonstrated by transient and permanent conduction abolition following radiofrequency application in two separate ventricular and atrial sites. These findings may explain the failure to ablate accessory pathway by radiofrequency application in the ventricular side of the mitral annulus guided by retrograde atrial activation occasionally observed in patients with a concealed accessory pathway.

[Coxiella burnetii endocarditis: long-term clinical course in 20 patients]

INTRODUCTION AND OBJECTIVES

Coxiella burnetii is a causative agent of increasingly frequent subacute infective endocarditis, and is associated with elevated morbimortality. Our aim in the present study was to assess the clinical, serological and therapeutic long-term evolution of 20 patients with Coxiella burnetii endocarditis.

METHODS

Twenty patients (13 male and 7 female, age 42 +/- 10 years) admitted between 1982 and 1996 were retrospectively studied. All of them fulfilled the Duke criteria modified by Raoult for Q fever endocarditis.

RESULTS

Endocarditis involved prosthetic and native valves in 14 and 6 patients, respectively. All patients except one received antibiotic treatment. Patients treated with doxycycline in monotherapy showed worse evolution than those treated with doxycycline in combination with other antibiotics. Valve replacement was performed in 15 patients, due to prosthetic dysfunction in most of them. The overall mortality was 40% (8 patients). At follow-up of 74 months (range 19-156) (mean 74 +/- 47) all patients showed persistent high levels of phase I antibodies. At follow-up of 15 to 65 months (32 +/- 30) antibiotic treatment was suspended in five patients because they were asymptomatic and without microbiologic findings of valvular endocarditis.

CONCLUSIONS

Q fever endocarditis was associated with severe complications, which often required valve replacement. All patients showed persistent high serological titers of Coxiella burnetii endocarditis without other signs of active infection. This finding raises the issue of suspending antibiotic treatment in patients with negative microbiologic findings and questions the persistence of abnormal serology as a monitor of treatment efficacy.

Successful treatment of prosthetic aortic valve mucormycosis

Mucor endocarditis after cardiovascular surgery is rare and usually fatal. We report the first known case of prosthetic aortic valve mucormycosis in a patient without predisposing risk factors who was successfully treated using a combination of early antifungal drug therapy and surgical removal of infected material.

Transient entrainment of bundle-branch reentry by atrial and ventricular stimulation: elucidation of the tachycardia mechanism through analysis of the surface ECG

BACKGROUND

Different responses to entrainment have been reported in relation to the pacing site of a variety of tachycardias. However, transient entrainment of bundle-branch reentrant tachycardia (BBRT) has not been investigated systematically.

METHODS AND RESULTS

We attempted entrainment of 13 BBRTs in 9 patients by pacing first the right ventricle and then the right atrium. The initial pacing cycle length (CL) was 10 ms faster than the tachycardia CL. Subsequent pacing sequences were performed with 5- to 10-ms CL decrements until tachycardia termination or loss of postatropine 1:1 AV conduction. Both full ventricular-paced and AV-conducted QRS complex references were obtained during sinus rhythm pacing from the same sites and with similar CL as during entrainment. Transient entrainment was achieved by ventricular and atrial stimulation in 11 and 8 tachycardias, respectively. Constant fusion was always present during entrainment by ventricular stimulation. There was no change in the QRS complex (orthodromically concealed fusion) during entrainment by atrial stimulation in 6 of 6 tachycardias with left bundle-branch block morphology and in 1 of 2 tachycardias with right bundle-branch block morphology.

CONCLUSIONS

BBRT, especially if it has a left bundle-branch block morphology, can be differentiated from other wide-QRS-complex tachycardia mechanisms through analysis of the ECGs recorded during tachycardia entrainment by atrial and ventricular stimulation. This diagnostic approach may be especially useful when it is difficult to record a stable or sufficiently sized His bundle electrogram or when spontaneous changes in the ventricular CL precede similar changes in the His bundle CL.

Characterization of a new HLA-B*38 allele (B*3803) in a Spanish Caucasian individual which is closely related to the Oriental B*38021 and B*39021 alleles

The broad HLA-B16 serologic specificity is divided into B38 and B39 splits associated to Bw4 and Bw6, respectively. Differential serologic variants have been defined for several molecular subtypes of B39 and for B38. We found a Spanish Caucasian individual carrying a B16 Bw4-associated antigen which was not recognized by reagents against B16 splits. Sequencing analysis showed a new B16 subtype termed B*3803. HLA class I sequence-based typing (SBT) analysis demonstrated that B*3803 co-segregates with A*2608 and Cw*1203, forming a common Caucasian haplotype. Sequence comparison with B*38 and B*39 subtypes evidences that although B*3803 is close related to B*3802, it only differs from B*39021 by six clustered nucleotide position in the Bw4/Bw6 motif, and strongly suggests that B*3803 could have evolved from, or be the ancestral gene of the Oriental-associated B*3802 and B*39021 alleles. However, more complex patterns of genetic events should be considered due to the Caucasian background of the B*3803 individual an its associated haplotype.

Characterization of a new HLA-B18 allele, B*1806, which lacks expression of the Bw6 epitope

HLA-B18 is a well defined Bw6-associated serologic specificity. Up to now, four different sequences have been characterised in Caucasian populations (B*1801,3,4,5), and one in Orientals (B*1802). We report a new HLA-B18 subtype (B*1806) which was serologically detected in a Spanish Caucasian individual as a B18 Bw4-associated antigen. Complete coding region sequencing showed that B*1806 differs from B*1801 in a unique nucleotide at position 299 (A to T), giving rise to an amino acid replacement in residue 76 (glutamic acid to valine) placed at the alpha1 domain. Therefore, in contrast to the serologic results, B*1806 possesses the canonical Bw6 motif at position 77-83. Subsequent flow cytometric assays proved that B*1806 evidences neither Bw4 nor Bw6 epitopes. Only three additional HLA-B alleles encode valine at codon 76, B*4601, B*7301 and B*5503, and like B*1806, all of them would include a Bw6 motif associated to the negative recognition by Bw6 antibodies. These findings support that valine at position 76 will modify the Bw6 epitope drastically, and suggest that this group of HLA-B alleles would define a third, Bw4 and Bw6-negative, lineage of molecules. Furthermore, valine 76 will also prevent the binding of Bw6 antibodies to those HLA-C antigens with the canonical Bw6 epitope (Cw*1,3,7,8,12,13,14,16).