Association between atrial fibrillation and cardiac implantable defibrillator detected heart failure status

Funding Acknowledgements

Type of funding sources: None.

Background

In heart failure (HF) patients, atrial fibrillation (AF) is a common comorbidity and is associated with a worse prognosis. Implantable defibrillator (ICD) diagnostics allow continuous monitoring of atrial high-rate events (AHRE), as a surrogate of AF, and are equipped with algorithms for HF monitoring. We evaluated the association between the values of the multisensor HF HeartLogic Index and the incidence of AF, and assessed the performance of the Index in detecting follow-up periods of significantly increased AF risk.

Methods

The HeartLogic feature was activated in 568 ICD patients. The median follow-up was 25 months [25th–75th percentile: 15-35]. The HeartLogic algorithm calculates a daily HF index and identifies periods IN the alert state on the basis of a configurable threshold. The endpoints were: daily AF burden of ≥5 minutes, ≥6 hours and ≥23 hours.

Results

The HeartLogic index crossed the threshold value 1200 times (0.71 alerts/patient-year). The time IN the alert state was 13% of the total observation period. During the observation period, an AF burden of ≥5 minutes/day was documented in 183 (32%) patients, ≥6 hours/day in 118 (21%) patients, and ≥23 hours/day in 89 (16%). On using a time-dependent Cox model, the weekly time IN the alert state was independently associated with an AF burden of ≥5 minutes/day (HR:1.95, 95%CI:1.22-3.13, p=0.005), ≥6 hours/day (HR:2.66, 95%CI:1.60-4.44, p<0.001), and ≥23 hours/day (HR:3.32, 95%CI:1.83-6.02, p<0.001), after correction for baseline confounders. Comparison of the episode rates in the IN-alert state with those in the OUT-of-alert state yielded HRs ranging from 1.57 to 3.11 for AF burden from ≥5 minutes to ≥23 hours.

Conclusions

The HeartLogic alert state was independently associated with AF occurrence. The intervals of time defined by the algorithm as periods of increased risk of HF allow risk stratification of AF according to various thresholds of daily burden.

Improvement in electrical synchrony during bi-ventricular vs. left ventricular pacing with dynamic atrioventricular delays may be predicted by conduction times

Funding Acknowledgements

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

Introduction

Automatic adjustment of atrioventricular delay (AVD) with SyncAV has been shown to improve electrical synchrony with either biventricular (BiV) or left ventricular (LV) only pacing. Selecting the optimal pacing mode may be guided by measuring conduction delays between the right atrium (RA), right ventricle (RV), and LV.

Purpose

Evaluate correlations between inter-chamber conduction delays and the QRS duration (QRSd) reduction achieved by BiV or LV-only pacing with SyncAV.

Methods

CRT implant patients (LBBB, QRSd ≥ 150 ms) were prospectively enrolled. Blinded QRSd was measured from 12-lead ECG during BiV and LV-only pacing, with SyncAV enabled and optimized to minimize QRSd. Conduction delays were measured by the device from unipolar electrograms during pacing and sensing (e.g. RAp-RVs). Correlations between each delay and which mode had the narrower QRSd was assessed by binomial regression.

Results

In total, 68 patients were evaluated (66.1 yr, 67.1% male, 32.5% ischemic, 26.3% EF, 165.1 ms intrinsic QRSd). BiV+SyncAV and LV+SyncAV reduced QRSd by 23.8% and 21.3% (P<0.001) vs. intrinsic conduction. Of all delays, RVs-LVs and LVp-RVs were significantly correlated with patient probability of BiV+SyncAV yielding a narrower QRSd than LV+SyncAV. BiV+SyncAV was favored in 70.6% (48/68) of all patients, but was favored in 92.3% (24/26) of patients with LVp-RVs < median (143 ms) (P=0.030 vs all).

Conclusion

When combined with SyncAV, BiV yielded a narrower QRSd than LV-only in the majority of patients, but was favored in a greater proportion who exhibit LVp-RVs delays below the median. Such conduction delay cut-offs can be used to facilitate pacing mode selection.

Impact of pacing configuration and right ventricular lead location on dynamic atrioventricular delay optimization

Funding Acknowledgements

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

Introduction

Automatic adjustment of atrioventricular delay (AVD) with SyncAV has been shown to improve electrical synchronization. However, the effect of pacing configuration and right ventricular (RV) lead location on SyncAV programming is unknown.

Purpose

  Evaluate the effect of pacing configuration and lead location on SyncAV optimization during biventricular (BiV) and LV-only pacing, with and without MultiPoint Pacing (MPP).

Methods

  Patients with LBBB and QRS duration (QRSd) ≥ 150 ms scheduled for CRT-P/D device implantation with quadripolar LV lead were enrolled in this prospective study. RV lead location was classified at implant by the operator via  fluoroscopy. QRSd was measured post-implant from 12-lead surface ECG by blinded experts during the following pacing modes: intrinsic conduction, BiV (BiV = RV + LV1), MPP (MPP = RV + LV1 + LV2), LV-only single-site (LVSS = LV1 only), and LV-only MPP (LVMPP = LV1 + LV2). For each mode, SyncAV was enabled (e.g. BiV + SyncAV) with the patient-tailored SyncAV offset that minimized QRSd. For BiV and LVSS, LV1 was the latest activating LV cathode; for MPP and LVMPP, LV1 + LV2 were the two LV cathodes with the widest possible separation (≥30mm). All modes used minimal RV-LV and LV1-LV2 delays.

Results

  Fifty-three patients (68% male, 36% ischemic, 26% ejection fraction, 169 ms intrinsic QRSd) completed device implant and QRSd assessment. RV leads were implanted in either the septum (48%) or apex (52%), according to implanting physician preference. Relative to intrinsic conduction, BiV + SyncAV and MPP + SyncAV reduced QRSd by 23% and 27%, respectively (p < 0.01). LVSS + SyncAV reduced QRSd by 22% (p < 0.01 vs BiV + SyncAV), and LVMPP + SyncAV reduced QRSd by 25% (p < 0.05 vs MPP + SyncAV). RV apex or septum lead location did not have a significant impact on QRS reduction for each pacing configuration. As a percent of PR interval, optimal SyncAV offsets were similar for BiV + SyncAV and MPP + SyncAV (16% vs 13%, p = 0.05), and for LVSS + SyncAV and LVMPP + SyncAV (18% vs 21%, p = 0.46), but were significantly higher for LV-only settings vs. corresponding BiV/MPP settings (p < 0.05 for both pairs). For BiV + SyncAV, apical vs septal RV leads required greater SyncAV offsets (22% vs 11%, p < 0.05). SyncAV offsets also tended to be higher in apical vs septal RV leads for MPP (21% vs 11%), LVSS (20% vs 15%), and LVMPP (25% vs 16%), but without statistical significance.

Conclusion

SyncAV improves acute electrical synchronization in CRT patients with LBBB, particularly with patient-specific SyncAV programming. Pacing configuration (RV + LV or LV only, with or without MPP) and RV lead location (apex or septum) could potentially influence optimal SyncAV programming. Abstract Figure.

P1151Impact of ARNI (LCZ696) on patients selection for ICD implantation in SCD primary prevention: a real-world experience

Background

 ICD implantation is recommended for primary prevention in patients with symptomatic NYHA II-III heart failure with reduced ejection fraction (< 35%) (HFrEF) and without left ventricle ejection fraction (LVEF) improvement despite at least three months of guideline-directed therapy. The use of angiotensin receptor-neprilysin inhibition with LCZ696 has shown to ameliorate left ventricle function and to reduce the ventricular arrhythmias burden in patients with HFrEF.

Purpose

The profile of patients with HFrEF who may benefit from therapy with LCZ696 without further requiring an ICD in primary prevention is still unknown. We aimed to assess the prevalence of these patients and to find potential clinical predictors of responsiveness to this treatment.

Methods

 We enrolled consecutive patients that started LCZ696 treatment for medical therapy optimization in the heart failure clinic of our institution. All of them were previously implanted with an ICD before LCZ696 availability (from 2009 to 2015). A cardiologist evaluated their home medications, clinical, and echocardiographic characteristics both at baseline (before starting LCZ696) and during follow up. The patients were grouped also according to the etiology of HF (ischemic/non-ischemic) and by gender. Patients were excluded if candidates to cardiac resynchronization therapy. Responsiveness to LCZ696 treatment was defined as an increase of LVEF to values > 35% at follow up (FU).

Results

A total of 49 patients (67.1 ± 9.8 years of age) were enrolled in this study and followed in the heart failure clinic of our institution (mean follow up 11.5 ± 4.9 months). Among them, 19 patients (38%) showed an increase in LVEF to values > 35% at follow up and a significant improvement in LVEF was appreciated (baseline LVEF: 31.2 ± 4.5 vs. follow up LVEF: 35.4 ± 8.0; p 0.003). No significant differences were recorded at baseline in LVEF within HF etiology and gender groups. At follow up, we found a significant increase in post-therapy LVEF only in the non-ischemic etiology group (from 31.5 ± 4.4 to 37.1 ± 8.1, p = 0.001) and in the male group (from 31.4 ± 4.5 to 34.9 ± 7.9, p = 0.005) in comparison with the ischemic etiology and the female group, respectively. No significant statistical differences were appreciated between responders and non-responders neither in terms of home medications nor in the LCZ696 doses, both at baseline and follow up.

Conclusion

This study suggests a potential impact of angiotensin receptor-neprilysin inhibition therapy in the selection of patients with HFrEF candidates to ICD in primary prevention. In this real-world experience from our HF clinic, we found a significant LVEF improvement in approximately 40% of patients treated with LCZ696. These patients, in FU evaluation, would not have needed for an ICD implantation. This benefit appears related to the non-ischemic etiology of HF and the male gender.

Abstract Figure. LVEF VARIATIONS

48Remote monitoring of Heart Failure patients with a Multisensor ICD Algorithm: value of an alert-based follow-up strategy

Background

The HeartLogic algorithm measures and combines multiple parameters, i.e. heart sounds, intrathoracic impedance, respiration pattern, night heart rate, and patient activity, in a single index. The associated alert has proved to be a sensitive and timely predictor of impending heart failure (HF) decompensation, and the HeartLogic alert condition was shown to identify patients during periods of significantly increased risk of HF events.

Purpose

To report the results of a multicenter experience of remote HF management with HeartLogic algorithm and appraise the value of an alert-based follow-up strategy.

Methods

The HeartLogic feature was activated in 104 patients (76 male, 71 ± 10 years, left ventricular ejection fraction 29 ± 7%). All patients were followed according to a standardized protocol that included remote data reviews and patient phone contacts every month and at the time of HeartLogic alerts. In-office visits were performed every 6 months or when deemed necessary.

Results

During a median follow-up of 13[11-18] months, centers performed remote follow-up at the time of 1284 scheduled monthly transmissions (10.5 per pt-year) and 100 HeartLogic alerts (0.82 alerts/pt-year). The mean delay from alert to the next monthly remote data review was 14 ± 8 days. Overall, the patient time in the alert state (i.e. HeartLogic index above the threshold) was 14% of the total observation period. HF events requiring active clinical actions were detected at the time of 11 (0.9%) monthly remote data reviews and at 43 (43%, p < 0.001) HeartLogic alerts. Moderate to severe symptoms of HF were reported during 2% of remote visits when the patient was out of HeartLogic alert condition and during 15% of remote visits performed in alert condition (p < 0.001). Out of 100 alerts, 17 required an in-office visit and 5 a hospitalization to manage the clinical condition. Overall, 282 scheduled and 56 unscheduled in-office visits were performed during follow-up. Any HF sign (i.e. S3 gallop, rales, jugular venous distension, edema) was detected during 18% of in-office visits when the patient was out of HeartLogic alert condition and during 34% of visits performed in alert condition (p = 0.002).

Conclusions

HeartLogic alerts are frequently associated with relevant actionable HF events. Events are detected earlier and the volume of alert-driven remote follow-ups is limited when compared with a monthly remote follow-up scheme. The probability of detecting common signs and symptoms of HF at regular remote or in-office assessment is extremely low when the patient is out of HeartLogic alert state. These results support the adoption of an alert-based follow-up strategy.

841Multi-center clinical experience with the usage of implantable pulse generators for permanent his bundle pacing

Funding Acknowledgements

Abbott

Introduction

His Bundle pacing (HBP) offers a more physiologic pacing approach to maintain electrical synchrony. Permanent HBP has emerged as a feasible and safe alternative to traditional pacemaker therapy and cardiac resynchronization therapy (CRT) with clinical and electrophysiological advantages. However, traditional implantable pulse generators (IPGs) have been used for HBP without supporting algorithms developed for HBP.

Objective

To assess a multi-center clinical experience with the usage of IPGs for permanent HBP and to identify the needs for HBP specific device algorithms.

Methods

Patients from 6 centers worldwide with a permanent HBP lead and an existing Abbott pacemaker, defibrillator, or CRT device were enrolled in this study. Device data and 12-lead surface ECG were collected simultaneously during device interrogation at a follow-up visit. HBP capture types at different pacing amplitudes were adjudicated using 12-lead ECG. Bundle branch block (BBB) correction by HBP was defined as QRS duration ≤130 ms or narrowing by >20%. Amplitudes of atrial and ventricular components on the HBP lead from both unipolar and bipolar sensing configurations were measured. Amplitudes of atrial component ≥ 0.5 mV on HB sensing EGMs were measured and considered as having risk of atrial oversensing.

Results

A total of 133 patients (75 ± 10 yrs, 92 male) were enrolled and completed study data collection post implant (median: 48, range: 0-3110 days). Patient characteristics, IPG type, and HBP lead connections were shown in the table. Dual-chamber pacemaker with HBP lead connected to V port was the most popular (65%) configuration. In non-BBB patients, pacing thresholds for selective HB (n = 44), non-selective HB (n = 54), and myocardial capture (n = 21) were 1.5 ± 1.2, 2.9 ± 2.0, 1.4 ± 1.5 V, respectively, at pulse width of 0.8 ± 0.4 ms. In BBB patients, LBBB and RBBB were corrected in 10/23 (43%) and 12/27 (44%) patients with pacing thresholds of 3.5 ± 2.4 and 2.1 ± 2.0 V, respectively, at pulse width of 0.8 ± 0.3 ms. AutoCapture™ algorithm was tested in 63 patients and recommended to be OFF in 28 (44%) patients. EGMs during intrinsic AV conduction were collected in 86 patients. A risk of atrial oversensing was identified in 24 (28%) and 27 (31%) patients during bipolar and unipolar sensing, respectively, and in 17 (20%) patients during both configurations. The average amplitude of the atrial and ventricular components on the HB lead EGM were 2.1 ± 2 and 6.0 ± 5.8 mV during bipolar sensing and 1.3 ± 1.2 and 6.3 ± 6.5 mV during unipolar sensing, respectively. Five (6%) patients had A/V amplitude ratios higher than 1.

Conclusions

Currently, various device configurations are used to overcome the fact that IPGs are not designed for HBP. Additionally, HBP presents unique challenges to ensure appropriate capture and sensing beyond traditional RV pacing. HBP specific device algorithms are needed to ensure correct IPG usage and facilitate device programming.

Abstract Figure.

855Performance of a multisensor icd algorithm in heart failure patient management

Funding Acknowledgements

No funding

Background

The HeartLogic index combines data from multiple implantable cardioverter-defibrillator (ICD)-based sensors and has proved to be a sensitive and timely predictor of impending heart failure (HF) decompensation.

Purpose

To describe a multicenter experience of remote HF management of patients who received a HeartLogic-enabled ICD or cardiac resynchronization therapy ICD (CRT-D).

Methods

The HeartLogic feature was activated in 104 patients (76 male, 71 ± 10 years, left ventricular ejection fraction 29 ± 7%). In accordance with a standardized follow-up protocol, remote data reviews and patient phone contacts were performed monthly and at the time of HeartLogic alerts (when the index crossed the nominal threshold value of 16), to assess the patient decompensation status. In-office visits were performed every 6 months or when deemed necessary.

Results

During a median follow-up of 13[11-18] months, 100 HeartLogic alerts were reported (0.82 alerts/pt-year) in 53 patients. 60 HeartLogic alerts were judged clinically meaningful (i.e. associated with worsening of HF or resulted in active clinical actions). Specifically, multiple associated conditions were reported: 45 (75%) symptoms or signs of clinical deterioration of HF, 13 (22%) discontinuations or reductions of prescribed HF therapy, 11 (18%) declines in CRT percentage (with or without new onset atrial fibrillation), 8 (13%) recurrences of previous HF events. For 48 out of 60 alerts the clinician was not previously aware of the condition. Of these, 43 alerts triggered multiple clinical actions. Alert-triggered actions were: 30 (70%) diuretic dosage increases, 15 (35%) other drug adjustments, 6 (14%) HF hospitalizations, 3 (7%) device reprogramming/revisions, 1 (2%) cardioversion, 1 (2%) patient education on therapy adherence. Out of 40 non-clinically meaningful alerts (0.33 alerts/pt-year), 8 (20%) were associated with non-HF therapy changes or interventions, 3 (8%) with pulmonary events, 29 (72%) remained unexplained. The overall number of HF hospitalizations was 16 (rate 0.13 hospitalizations/pt-year). Five HF hospitalizations were not preceded by HeartLogic alert (0.04 hospitalizations/pt-year).

Conclusions

The HeartLogic index provided clinically meaningful information and allowed to remotely identify relevant HF related clinical conditions, with a low rate of unexplained detections and undetected HF events. In this experience, remote monitoring using HeartLogic alerts allowed to drive HF care and take effective clinical actions.

862Syncav with multipoint pacing improves acute left ventricular hemodynamics

Funding Acknowledgements

Abbott

Introduction

SyncAV has been shown to improve electrical synchronization by automatically adjusting atrioventricular delay (AVD) according to the intrinsic atrioventricular conduction time. Additional incremental electrical synchronization may be gained by the addition of second left ventricular (LV) pulse with MultiPoint Pacing (MPP). While the electrical synchronization benefits of SyncAV have been previously explored, there has been no assessment of the acute hemodynamic impact of SyncAV with or without MPP.

Objective

 Evaluate the acute LV hemodynamic impact of SyncAV with and without MPP.

Methods

Heart failure patients with LBBB and QRS duration (QRSd) > 140 ms undergoing CRT-P/D implant with a quadripolar LV lead were enrolled in this prospective study. A guidewire or catheter with pressure transducer was placed in the LV chamber and the maximum pressure change (dP/dtmax) was recorded during the following pacing modes:  intrinsic conduction, conventional biventricular pacing with SyncAV (BiV + SyncAV), and MPP with SyncAV (MPP + SyncAV). Twelve-lead surface ECG was used to determine the patient-tailored SyncAV offset that minimized QRSd.

Results

Twenty-seven patients (67% male, 44% ischemic, 30 ± 7% ejection fraction) completed the acute recordings. Relative to the intrinsic QRSd of 163 ms, BiV + SyncAV reduced QRSd by 21.5% to 124 ms (p < 0.001 vs. intrinsic) and MPP + SyncAV reduced QRSd by 26.6% to 120 ms (p < 0.05 vs. BiV + SyncAV). Beyond electrical synchronization, SyncAV significantly improved acute hemodynamics. Relative to the intrinsic dP/dtmax of 842 mmHg/s, BiV + SyncAV elevated dP/dtmax by 6.3% to 900 mmHg/s (p < 0.001 vs. intrinsic) and MPP + SyncAV elevated dP/dtmax by 8.8% to 926 mmHg/s (p < 0.005 vs. BiV + SyncAV). Despite both QRSd and dP/dtmax improvement with SyncAV and MPP, correlation between electrical and hemodynamic measurements was poor (R2 = 0.0 for BiV + SyncAV, R2 = 0.1 for MPP + SyncAV).

Conclusion

SyncAV may significantly improve acute LV hemodynamics in addition to electrical synchrony in LBBB patients. Further incremental improvement was achieved by combining SyncAV with MPP.

Abstract Figure.

43Dynamic atrioventricular delay achieves superior electrical synchrony when pacing both ventricles rather than left ventricle alone

Funding Acknowledgements

Abbott

Introduction

Automatic adjustment of atrioventricular delay (AVD) with SyncAV has been shown to improve electrical synchronization when pacing one or two sites in the left ventricle together with the right ventricle. However, it is unknown if the same benefit can be gained by using SyncAV while pacing only the left ventricle without right ventricular pacing.

Purpose

  Evaluate the acute improvement in electrical synchrony provided by SyncAV with and without MultiPoint Pacing (MPP) during biventricular (BiV) and LV only pacing.

Methods

  Patients with LBBB and QRS duration (QRSd) ≥ 150 ms scheduled for CRT-P/D device implantation with quadripolar LV lead were enrolled in this prospective study. QRSd was measured post-implant from 12-lead surface electrograms by blinded experts during the following pacing configurations: intrinsic conduction, conventional BiV (BiV = RV + LV1), MPP (MPP = RV + LV1 + LV2), LV-only single-site (LVSS = LV1 only), and LV-only MPP (LVMPP = LV1 + LV2). For each pacing mode, SyncAV was enabled (e.g. BiV + SyncAV) with the patient-tailored SyncAV offset that minimized QRSd. As an additional reference, QRSd during BiV was also measured using the nominal static AVD (paced/sensed AVD = 140/110 ms). BiV and LVSS pacing used the latest activating LV cathode, whereas MPP and LVMPP used the two LV cathodes with the widest possible separation (>30mm). All configurations used the minimum programmable RV-LV and LV1-LV2 delays.

Results

  Thirty-five patients (78% male, 33% ischemic, 26% ejection fraction, 165 ms intrinsic QRSd) completed device implant and QRSd assessment. Relative to intrinsic conduction, BiV with nominal AVD reduced the QRSd by 17.5% (p < 0.001 vs intrinsic). Enabling SyncAV with a patient-optimized offset significantly improved QRSd reduction. BiV + SyncAV reduced QRSd by 25.2% (p < 0.001 vs. BiV). The greatest QRSd reduction of 28.9% was achieved by MPP + SyncAV (p < 0.01 vs. BiV + SyncAV). Single- and multi-site LV-only pacing reduced QRSd significantly less than corresponding biventricular modes. LVSS + SyncAV reduced QRSd by 22.5% (p < 0.05 vs. BiV + SyncAV), and LVMPP + SyncAV reduced QRSd by 24.3% (p < 0.05 vs. MPP + SyncAV). As a percent of PR interval, optimal SyncAV offsets were similar for BiV + SyncAV (median: 13%, mean: 17%) vs. MPP + SyncAV (median: 13%, mean 16%, p = 0.35 vs. BiV + SyncAV), and similar for LVSS + SyncAV (median: 20%, mean: 28%) and LVMPP + SyncAV (median: 23%, mean: 26%, p = 0.35 vs. LVSS + SyncAV), but were significantly higher for LV-only settings vs. corresponding BiV/MPP settings (p < 0.01 for both pairs). Conclusion: Greater improvement in electrical synchrony using SyncAV was observed when right ventricular pacing was included with left ventricular pacing. Additional benefit was gained by the addition of a second left ventricular pacing site with MPP in combination with SyncAV in both biventricular and LV only pacing modes.

Abstract Figure.

Biofilm in voice prosthesis: A prospective cohort study and laboratory tests using sonication and SEM analysis

OBJECTIVE

The objective of the study was to compare the biofilm growing pattern and its morphological extent on silicone and a teflon-like material using a sonication process and a Scanning Electron Microscope (SEM).

DESIGN

A prospective cohort study and a laboratory study.

SETTING

Otolaryngology -Head and Neck surgery Department and the Microbiology Institute.

PARTICIPANTS

The participants included fifteen laryngectomised patients with phonatory prostheses, which were removed because of device failure, and two different kinds of phonatory prostheses from the laboratory (Provox 2 and ActiValve) that were artificially colonised by Candida albicans.

MAIN OUTCOME MEASURES

Tracheo-oesophageal puncture (TEP) is currently considered the gold standard for post-laryngectomy voice rehabilitation. "Leakage" represents the most common cause of substitution and is generated by biofilm colonisation of the prosthesis by mixed mycotic and bacterial agents. New biomaterials have been developed that are deemed to be more resistant to the colonisation of micro-organisms and material deformation.

RESULTS

The devices showed colonisation by mixed bacterial flora (Staphylococci 13%, Streptococci 9%, and Haemophilus influenzae 5%) and by yeasts (Candida albicans 12%). Moreover, we observed a different distribution of biofilm layers in Provox ActiValve (22.56%) compared to Provox 2 (56.82%) after experimental colonisation by the previously isolated Candida strain.

CONCLUSION

Resident microbiological species from the upper airways unavoidably colonise the polymer surfaces, and no strategies have been effective except for the manipulation of the chemical-physical properties of the device's polymer. Our study confirms that Provox ActiValve, which is made with a fluoroplastic material (teflon-like), is less subject to in vitro colonisation by Candida, and thus showed a higher clinical resistance to biofilm and a longer lifespan. The sonication seems to significantly improve the knowledge of bacterial and mycotic flora in biofilm colonisation. The design of a device for the daily cleaning capable to reach and brush the oesophageal flange of the prosthesis preserving the valve mechanism could represent a practical and simple help in this still unsolved problem.

A telemonitoring platform for the investigation of blood pressure profiles in pacemaker patients

Rate responsive pacemakers (PM) use different strategies to adapt the patient paced rate, with the aim of having the best hemodynamic performance in response to internal or external conditions. Closed-loop stimulation (CLS) uses intracardiac impedance as a sensor principle. The evaluation of impact of different pacing modalities and technologies on the blood pressure (BP) profiles is mainly investigated in short-term laboratory settings, mainly due to the need of reliable daily-based BP values. The impact of CLS pacing on systemic blood pressure (BP) has been studied on short term basis, but data on long term effects are scarse. This study present a telemedicine platform designed for evaluating the effect of the rate responsive technology on daily systolic and diastolic BP data. BP and pacemaker data were collected daily from fourteen patients during a 3 month period. The total number of monitoring days was 1277 (91 day/patient), for a total number of 4455 BP measures. On average 3.5 measure/day/patient were received). The analysis of the BP data showed that CLS pacing results in diastolic pressure closer to the normal values than accelerometer-based pacing, which were associated to lower diastolic pressures.

Os odontoideum in a patient with cervical vertigo: a case report

Cervical vertebral anomalies are often associated with malformations or traumas, they may be completely asymptomatic and represent an occasional finding in vertigo or can cause severe neurologic complications (ie, compression of the upper cervical spine with myelopathy, epilepsy, or respiratory failure). This clinical case is a patient who came to us for observation for a peripheral harmonic vestibular syndrome, and in whom a malformation of the cervical vertebral joint (os odontoideum) was occasionally found on magnetic resonance imaging.

Urinary NO2- and NO3- evaluation by an ion chromatography system

We describe an ion chromatography system using a Dionex AS4A-SC column with carbonate-bicarbonate buffer (1.8-1.7 mM) as eluent for the evaluation of urinary NO2- and NO3-. This chromatographic system gives an accurate measurement of NO2- and NO3- in the urine as an index of NO production in vivo, making also possible to evaluate their relative proportion and providing useful tools to investigate the NO system.

Nifedipine can preserve renal function in patients undergoing aortic surgery with infrarenal crossclamping

Sixteen patients diagnosed with an aneurysm of abdominal aorta or Leriche disease underwent elective aortic surgery involving crossclamping of infrarenal aorta (ICC). These patients were randomized into two equal groups and 8 patients were infused with nifedipine starting from the isolation of aorta until the end of surgery (group A) while another 8 patients were infused with low-dose dopamine (group B) over the same surgical course. Plasma endothelin (ET) was measured before the induction of anesthesia, at the beginning and at the end of the clamp period and at the end of the operation. Intraoperatively, creatinine clearance and urinary excretion of PGE2, 6-keto PGF1 alpha and TxB2 were also determined before, during and after aortic crossclamping. Preoperative GFR as well as preinduction cardiac index (CI) and pulmonary capillary wedge pressure (PCWP) of the two groups did not differ. During cross-clamping plasma ET rose significantly in both groups. However, after clamp removal, plasma ET decreased in group A while it remained elevated in group B. Urinary excretion of TxB2, PGE2 and 6-keto PGF1 alpha increased during clamp in both groups, but the ratio of PGE2 + 6-keto PGF1 alpha/TxB2 during and after clamp was significantly higher in group A than in B. Postclamp creatinine clearance decreased in group B, and increased in group A; postoperative value of GFR was unchanged in group A and decreased significantly in group B. In conclusion, infusion of nifedipine, in contrast to dopamine, prevented the decrease of GFR in patients undergoing aortic surgery. This effect could be mediated by a nifedipine modulation of ET vascular synthesis and/or a preferential renal synthesis of vasodilating prostanoids.

Oxalate transport in cultured porcine renal epithelial cells

Oxalate-containing kidney stones are the most common type (75%) of renal stones. In order to control oxalate excretion in the urine, a basic understanding of the cellular transport of oxalate is imperative. We have utilized the technique of continuous cell culture to establish and characterize a model system to study renal epithelial cell (LLCPK1) oxalate transport. Our data demonstrate that oxalate uptake in these cells is dependent on time, concentration and energy. The Km for oxalate uptake was 200 microM. Oxalate uptake was decreased at lower temperatures and elevated in an acidic extracellular environment. Both anion exchange inhibitors DIDS and SITS inhibited oxalate uptake. Sulfate, chloride, and bicarbonate decreased oxalate uptake, as did the diuretics bumetanide and furosemide. There was no evidence for the co-transport of oxalate with sodium. Our data show that monolayers of cultured kidney epithelial cells are a valuable model system for study of the basic cellular mechanisms of oxalate transport.