Minute ventilation sensor-driven rate response as a part of cardiac resynchronization therapy optimization in older patients.

BACKGROUND: Chronotropic incompetence (CI) is common among elderly cardiac resynchronization therapy pacemaker (CRT-P) patients on optimal medical therapy. This study aimed to evaluate the impact of optimized rate-adaptive pacing utilizing the minute ventilation (MV) sensor on exercise tolerance. METHODS: In a prospective, multicenter study, older patients (median age 76 years) with a guideline-based indication for CRT were evaluated following CRT-P implantation. If there was no documented CI, requiring clinically rate-responsive pacing, the device was programmed DDD at pre-discharge. At 1 month, a 6-min walk test (6MWT) was conducted. If the maximum heart rate was < 100 bpm or < 80% of the age-predicted maximum, the response was considered CI. Patients with CI were programmed with DDDR. At 3 months post-implant, the 6MWT was repeated in the correct respective programming mode. In addition, heart rate score (HRSc, defined as the percentage of all sensed and paced atrial events in the single tallest 10 bpm histogram bin) was assessed at 1 and 3 months. RESULTS: CI was identified in 46/61 (75%) of patients without prior indication at enrollment. MV sensor-based DDDR mode increased heart rate in CI patients similarly to non-CI patients with intrinsically driven heart rates during 6MWT. Walking distance increased substantially with DDDR (349 ± 132 m vs. 376 ± 128 m at 1 and 3 months, respectively, p < 0.05). Furthermore, DDDR reduced HRSc by 14% (absolute reduction, p < 0.001) in those with more severe CI, i.e., HRSc ≥ 70%. CONCLUSION: Exercise tolerance in older CRT-P patients can be further improved by the utilization of an MV sensor.

Stroke in Patients with Atrial Fibrillation: Epidemiology, Screening, and Prognosis.

Atrial fibrillation (AF) is the most common sustained arrythmia and one of the strongest risk factors and causal mechanisms of ischemic stroke (IS). Acute IS due to AF tends to be more severe than with other etiology of IS and patients with treated AF have reported to experience worse outcomes after endovascular treatment compared with patients without AF. As cardioembolism accounts for more than a fifth of ISs and the risk of future stroke can be mitigated with effective anticoagulation, which has been shown to be effective and safe in patients with paroxysmal or sustained AF, the screening of patients with cryptogenic IS (CIS) for AF is paramount. Embolic stroke of undetermined source (ESUS) is a subtype of CIS with a high likelihood of cardioembolism. The European Stroke Organization and European Society of Cardiology guidelines recommend at least 72 h of screening when AF is suspected. The longer the screening and the earlier the time point after acute IS, the more likely the AF paroxysm is found. Several methods are available for short-term screening of AF, including in-hospital monitoring and wearable electrocardiogram recorders for home monitoring. Implantable loop monitors provide an effective long-term method to screen patients with high risk of AF after IS and artificial intelligence and convolutional neural networks may enhance the efficacy of AF screening in the future. Direct oral anticoagulants (DOACs) are preferred over vitamin K antagonists in both primary and secondary prevention of IS in AF patients. Recent data from the randomized controlled trials (RCT) also suggest that early initiation of DOAC treatment after acute IS is safe compared to later initiation. Anticoagulation treatment may still predispose for intracranial bleeding, particularly among patients with prior cerebrovascular events. Left atrial appendix closure offers an optional treatment choice for patients with prior intracranial hemorrhage and may offer an alternative to oral anticoagulation even for patients with IS, but these indications await validation in ongoing RCTs. There are still controversies related to the association of found AF paroxysms in CIS patients with prolonged screening, pertaining to the optimal duration of screening and screening strategies with prolonged monitoring techniques in patients with ESUS. In this review, we summarize the current knowledge of epidemiology, screening, and prognosis in AF patients with stroke.

Cardiac Magnetic Resonance Imaging-Based Screening for Cardiac Sarcoidosis in Patients With Atrioventricular Block Requiring Temporary Pacing.

Background Some myocardial diseases, such as cardiac sarcoidosis, predispose to complete atrioventricular block. The European Society of Cardiology Guidelines on cardiac pacing in 2021 recommend myocardial disease screening in patients with conduction disorder requiring pacemaker with multimodality imaging, including cardiac magnetic resonance (CMR) imaging. The ability of CMR imaging to detect myocardial disease in patients with a temporary pacing wire is not well documented. Methods and Results Our myocardial disease screening protocol is based on using an active fixation pacing lead connected to a reusable extracorporeal pacing generator (temporary permanent pacemaker) as a bridge to a permanent pacemaker. From 2011 to 2019, we identified 17 patients from our CMR database who underwent CMR imaging with a temporary permanent pacemaker for atrioventricular block. We analyzed their clinical presentations, CMR data, and pacemaker therapy. All CMRs were performed without adverse events. Pacing leads induced minor artifacts to the septal myocardial segments. The extent of late gadolinium enhancement in CMR imaging was used to screen patients for the presence of myocardial disease. Patients with evidence of late gadolinium enhancement underwent endomyocardial biopsy. If considered clinically indicated, also 18-F-fluorodeoxyglucose positron emission tomography and extracardiac tissue biopsy were performed if sarcoidosis was suspected. Eventually, 8 of 17 patients (47.1%) were diagnosed with histologically confirmed granulomatous inflammatory cardiac disease. Importantly, only 1 had a previously diagnosed extracardiac sarcoidosis at the time of presentation with high-degree atrioventricular block. Conclusions CMR imaging with temporary permanent pacemaker protocol is an effective and safe early screening tool for myocardial disease in patients presenting with atrioventricular block requiring immediate, continuous pacing for bradycardia.

Enhanced detection of atrial tachyarrhythmias with pacing devices by using more accurate atrial sensing.

PURPOSE: Cardiac pacing devices can detect and monitor atrial tachyarrhythmias (ATA) which increase the risk of thromboembolic complications. The aim of this study was to compare (1) two different atrial leads and (2) standard and optimized settings to detect ATA and reject far-field R-wave signal (FFRW). METHODS: This was a prospective, randomized multi-center trial comparing St. Jude Medical OptiSense lead (tip-to-ring spacing 1.1 mm) and Tendril lead (tip-to-ring spacing 10.0 mm), having programmed atrial sensitivity at 0.2 mV and post-ventricular atrial blanking at 60 ms. We measured intra-atrial amplitudes of FFRW, intrinsic atrial signals, the amount of FFRW oversensing, and other inappropriate mode switching. RESULTS: One hundred and ten patients were enrolled. The mean amplitude of sensed and paced FFRW bipolar signal was 0.13 mV vs. 0.21 mV (p < 0.001) and 0.13 mV vs. 0.26 mV (p < 0.001) with OptiSense and Tendril lead, respectively. The mean amplitude of the atrial bipolar signal was 2.84 mV with OptiSense and 3.48 mV with Tendril lead, p = 0.014. With the optimized settings with OptiSense lead, one patient out of 20 (5%) had FFRW oversensing, none had undersensing of ATAs due to 2:1-blanking of atrial depolarizations, and the concordance of the ATAs by Holter and pacemaker memory was high (Spearman's rank correlation coefficient = 0.90). In the Tendril group, 12 out of 25 patients (48%) had oversensing and 4 had atrial undersensing (p < 0.001). CONCLUSIONS: The technique with an atrial lead with short tip-to-ring spacing combined with optimized pacemaker programming resulted in reliable and accurate atrial arrhythmia detection. TRIAL REGISTRATION: ClinicalTrials.gov number NCT01074749.

Cardiac manifestations in Finnish gelsolin amyloidosis patients.

INTRODUCTION: Finnish gelsolin amyloidosis (AGel amyloidosis) is an inherited systemic amyloidosis with well-known ophthalmological, neurological and cutaneous symptoms. Additionally, cardiomyopathies, conduction disorders and need of cardiac pacemakers occur in some patients. This study focuses on electrocardiographic (ECG) findings in AGel amyloidosis and their relation to cardiac magnetic resonance (CMR) changes. We also assessed whether ECG abnormalities were associated with pacemaker implantation and mortality. MATERIALS AND METHODS: In this cohort study, 51 genetically verified AGel amyloidosis patients (mean age 66 years) without cardiac pacemakers underwent 12-lead ECG and CMR imaging with contrast agent in 2017. Patients were followed-up for 3 years. RESULTS: Conduction disturbances were found in 22 patients (43%). Nine (18%) presented with first-degree atrioventricular block, six (12%) with left anterior hemiblock, seven (14%) with left or right bundle branch block and two (4%) with non-specific intraventricular conduction delay. Low QRS voltage was present in two (4%) patients. Late gadolinium enhancement (LGE) concentrating on the interventricular septum and inferior parts of the heart was present in 19 (86%) patients with conduction abnormalities. During the follow-up, only one patient received a pacemaker, and one patient died. DISCUSSION: Conduction disorders and septal LGE are common in AGel amyloidosis, whereas other ECG and CMR findings typically observed in most common cardiac amyloidosis types were rare. Septal pathology seen in CMR may interfere with the cardiac conduction system in AGel amyloidosis, explaining conduction disorders, although pacemaker therapy is rarely required.

Prolonged ECG with a novel recorder utilizing electrode belt and mobile device in patients with recent embolic stroke of undetermined source: A pilot study.

BACKGROUND: Paroxysmal atrial fibrillation (pAF) is a major risk factor for ischemic stroke, but challenging to detect with routine short-term monitoring methods. In this pilot study, we present a novel method for prolonged ECG and screening for pAF in patients with a recent embolic stroke of unknown source (ESUS). METHODS: Fifteen patients aged ≥ 50 years with a recent ESUS were assigned to wear an external electrode belt-based 1-lead ECG device (Beat2Phone) continuously for 2 weeks (wear time). The device was operated via a mobile phone application in nonhospital conditions. The primary outcome was patient adherence to monitoring. Secondary outcomes were incidence of new pAF, quality-wise comparison to Holter, and usability of the novel ECG monitoring method with Systems Usability Scale (SUS). We also performed a 24- to 48-hr comparison between simultaneous Beat2Phone ECG and a standard Holter in 6 patients. RESULTS: Wear time of Beat2Phone device was over 80% in 5 (33.3%) patients, 50%-80% in 7 (46.6%) patients, and less than 50% in 3 (20%) patients. We detected pAF ≥ 30 s in 1 patient (6.7%). In the simultaneous monitoring with Beat2Phone and Holter, there were a total of 817 (out of 1979) analyzable periods of sinus rhythm or premature atrial or ventricular beats (Cohen's Kappa coefficient 0.92 ± 0.02 between Beat2Phone and Holter), and no pAF events. Beat2Phone ECG showed remarkable SUS scores in user evaluations (average score: 81.4 out of 100 on SUS). CONCLUSIONS: Beat2Phone device was easy to use among ESUS patients and in optimal conditions provided high-quality 1-lead ECG signal for diagnosing pAF. CLINICAL TRIAL REGISTRATION: The study was not registered, as it was a nonrandomized single-arm pilot study.

Continuous 4-week ECG monitoring with adhesive electrodes reveals AF in patients with recent embolic stroke of undetermined source.

BACKGROUND: Atrial fibrillation (AF) frequently escapes routine stroke workup due to its unpredictable and often asymptomatic nature, leaving a significant portion of patients at high risk of recurrent stroke. Recent trials emphasized continuous electrocardiogram (ECG) monitoring in the detection of occult AF. We screened AF in patients meeting the embolic stroke of unknown source (ESUS) criteria using an external miniaturized recorder with an adhesive electrode. METHODS: Patients aged ≥50 with recent ESUS were prospectively screened and assigned to wear a 1-lead ECG device capable to record continuous ECG for up to 4 weeks. Electrodes were replaced every 3-4 days. Primary outcome was proportion of patients completing at least 80% of monitoring. Secondary outcome measures included incidence of AF and initiation of oral anticoagulation therapy after AF detection. RESULTS: Fifty-seven patients were monitored (mean age 64.5 ± 8.2 years, median delay from stroke to the start of monitoring 8 days, IQR 4-44). Of these, 51 patients (89.5%) completed at least 80% of the desired monitoring period. We detected AF ≥30 s in seven patients (12.3%), all of whom initiated anticoagulation therapy. Atrial fibrillation was revealed in six patients (85.7%) within the first week of monitoring. Compared to patients without AF, patients with AF were older (70.6 ± 5.1 vs. 63.6 ± 8.3 years, p < 0.011) and more obese (body mass index 30.0 ± 3.4 vs. 26.6 ± 4.6, p < 0.039). CONCLUSIONS: Prolonged ECG monitoring with an external device using adhesive electrodes is feasible in ESUS patients, since nine out of ten patients used the device appropriately and AF was detected in one out of eight patients.

Effect of lead design and pacing vector on electrical parameters of quadripolar coronary sinus leads: The RALLY-X4 study.

BACKGROUND: Various lead designs have been developed to accommodate different coronary sinus anatomies. Our objectives were to compare electrical parameters of straight and spiral left ventricular leads, to evaluate capture thresholds and impedances using different pacing vectors, and to study evolution of thresholds over time. METHODS: The RALLY-X4 study enrolled patients implanted with a lead from the Acuity X4 family (straight, spiral short, or spiral long). Electrical parameters (including capture thresholds from all 17 vectors) were measured at baseline and follow-up. RESULTS: Data from 795 patients who were successfully implanted were analyzed. Straight and spiral leads had similar proportions of patients with thresholds <2.5 V/0.4 ms using the distal electrode (61-65% of patients) or from at least one of the proximal (E2-E4) electrodes (81-83% of patients). Unipolar vectors had significantly lower thresholds and impedances than bipolar vectors, with similar measurements compared to extended bipolar configurations. Capture thresholds increased with more proximal electrodes for all leads. Over a mean follow-up of 1 year, a slight decrease in capture thresholds was observed. CONCLUSION: Straight and spiral quadripolar leads allow to obtain clinically acceptable capture thresholds from at least one of the proximal electrodes in >80% of patients. Pacing vectors significantly affect electrical parameters, with higher thresholds in more proximal electrodes and lower thresholds with unipolar and extended bipolar configurations. Capture thresholds slightly decreased over a mean follow-up of 1 year.

Clinical experience of magnetic resonance imaging in patients with cardiac pacing devices: unrestricted patient population.

Background: Magnetic resonance imaging (MRI) in patients with cardiac pacing devices has become available despite previously being considered absolutely contraindicated. However, most institutional safety protocols have included several limitations on patient selection, leaving MRI unavailable for many patients. Purpose: To evaluate the first 1000 MRI examinations conducted on patients with cardiac pacing devices at Helsinki University Hospital for any potential safety hazards and also to evaluate the long-term functionality of the safety protocol in "real-life" clinical practice. Material and Methods: A total of 1000 clinically indicated MRI scans were performed with a 1.5-T MRI scanner according to the safety protocol. The following information was collected from the electronic medical record (EMR): patients' date of birth; sex; pacing device generator model; date of MRI scan; date of the latest pacing device generator implantation; and the body region scanned. The EMR of these patients was checked and especially searched for any pacing device related safety hazards or adverse outcomes during or after the MRI scan. Results: Only one potentially dangerous adverse event was noted in our study group. In addition, patients with abandoned leads, temporary pacing devices, and newly implanted pacing device generators were scanned successfully and safely. Conclusion: MRI scans can be performed safely in patients with cardiac pacing devices if the dedicated safety protocol is followed.

Non-vitamin k antagonist oral anticoagulants in a European primary care physician survey.

BACKGROUND: Familiarity and competency in the options for stroke prevention in atrial fibrillation (AF) and the role of non-vitamin K antagonist oral anticoagulants (NOACs) may vary among primary care physicians (PCPs) from different European countries. AIMS: To investigate PCP views on prescribing and managing NOACs across Europe and identify perceived unmet needs. DESIGN & SETTING: Web-based survey including PCPs with particular interest in cardiovascular medicine. METHOD: A questionnaire was drawn up, containing 10 questions on initiation and ongoing management of NOACs; use of AF stroke guidelines on NOACs and anticoagulant switching; and perceived information needs. RESULTS: The overall response rate was 42%. The majority of PCPs declared they are responsible for and confident in both initiating and managing NOAC therapy. In some countries, PCPs are not able to initiate NOAC therapy due to administrative barriers (namely, Italy and Slovakia). No single set of guidelines is referred to across all countries and over a fifth of responders indicate they do not follow specific guidelines. The main learning needs reported were more related to initiation than to ongoing management of anticoagulant therapy. CONCLUSION: According to this self-assessment survey, the experience of most PCPs in management of different aspects of AF appears good and only some felt the need for further training. However, in the light of the importance of this topic as public health issue, intensified efforts aiming at better equipping PCPs to meet their key roles in an integrated service across Europe are overdue.

Left atrial appendage occlusion versus standard medical care in patients with atrial fibrillation and intracerebral haemorrhage: a propensity score-matched follow-up study.

AIMS: The aim of this study was to investigate the prognosis in patients with atrial fibrillation (AF) and intracerebral haemorrhage (ICH) having a left atrial appendage occlusion (LAAO) versus patients receiving standard medical therapy. METHODS AND RESULTS: A total of 151 patients from the Nordic countries with AF and previous ICH who underwent LAAO using the AMPLATZER Cardiac Plug or the AMPLATZER AMULET were compared to a propensity score-matched group of 151 patients receiving standard medical therapy. The two groups were matched so that their risks for stroke and bleeding were similar (CHA2DS2-VASc and HAS-BLED scores). The standard care patients were identified from the Danish Stroke Registry among 787 patients with AF and ICH. The primary endpoint was a composite of all-cause mortality, ischaemic stroke and major bleeding. Patients with AF and a prior ICH treated with LAAO had a lower risk of the composite outcome as compared to patients treated with standard medical care (events/1,000 years [95% confidence interval]: 53.3 [44.3-64.1] vs. 366.7 [298.2-450.9]; hazard ratio 0.16 [0.07-0.37]). CONCLUSIONS: LAAO is suggested to be of major clinical benefit in AF patients having sustained an ICH. These results have to be confirmed in a randomised clinical trial.

Cardiac MRI in patients with cardiac pacemakers: practical methods for reducing susceptibility artifacts and optimizing image quality.

BACKGROUND: Magnetic resonance imaging (MRI) of pacemaker patients has become available despite of previous contraindications. However, pacing systems containing ferromagnetic material may hamper the diagnostic quality of cardiac MR (CMR) images. PURPOSE: To study methods for reducing susceptibility-based artifacts in CMR examinations of pacemaker patients. MATERIAL AND METHODS: Altogether 16 patients were scanned with 1.5T MRI scanner using cine balanced steady-state free-precession (bSSFP) and spoiled gradient echo (SPGR) sequences. The use of frequency-scout was also evaluated. For myocardial late gadolinium-enhanced (LGE) imaging, SPGR or bSSFP readout inversion-recovery prepared gradient echo sequences were used with and without phase-sensitive inversion-recovery (PSIR). Two radiologists subjectively compared the image quality (IQ) and the ranges of susceptibility artifacts were evaluated objectively. RESULTS: The IQ proved adequate for diagnosing each patient, although in a few patients with a left-side implanted generator, artifacts hampered IQ in the anterior and anteroseptal segments of the myocardium in bSSFP cine and LGE sequences. In bSSFP cine, the use of frequency-scout could often transfer the banding artifacts away from the left ventricular myocardium. In LGE imaging, the artifacts were more pronounced in IR-bSSFP and PSIR than in IR-SPGR sequences. The ranges of generator-based artifacts were greater in bSSFP (10-12 cm) than in SPGR (6 cm) sequences due to banding artifacts. CONCLUSION: The artifacts caused by pacemakers typically did not compromise the diagnostic IQ. The use of frequency-scout prior to bSSFP cine or the use of SPGR-based sequences could also improve IQ.

Quality of prior warfarin therapy in ischemic stroke patients with a pre-stroke diagnosis of atrial fibrillation.

In atrial fibrillation (AF), warfarin prevents ischemic strokes (IS), but its implementation varies. We conducted a retrospective registry study on clinical features and prior warfarin therapy in AF patients with IS. Of our 540 patients, 143 had a prior diagnosis of AF, of which 51% used warfarin. Warfarin use was more common in those having permanent than paroxysmal AF (76% versus 36%, p<0.001). On admission, 42% had INR within the therapeutic range. Average TTR was 64%. Advanced age (p=0.009) and permanent AF (p<0.001) were associated with higher TTR. Better warfarin therapy quality was associated with advanced age and permanent AF.

[Magnetic resonance imaging of patients with cardiac pacemakers--a safe mode of operation]. / Sydämentahdistinpotilaiden magneettikuvaus--turvallinen toimintamalli.

Owing to potential serious safety risks, magnetic resonance imagings of patients having cardiac pacemakers have long been forbidden. Due to the increased demand, modes of operation have, however, been developed for safe imaging, taking the benefit-risk aspects into account. The mode of operation devised in collaboration between the HUCH Cardiology Outpatient Clinic and the radiology unit of the HUS Medical Imaging and Physiology makes safe magnetic resonance imagings possible without body area restrictions for all kinds of cardiac pacemaker patients. By using the developed mode of operation, imaging of 268 patients with cardiac pacemakers have already been carried out safely by the end of October 2014. We describe the content of the mode of operation and the current status of the investigations, with a brief look into the future.

Undetermined stroke with an embolic pattern--a common phenotype with high early recurrence risk.

INTRODUCTION: Undetermined strokes with an embolic pattern (USEP) represent a common phenotype. We assessed their frequency and compared USEP with cardioembolic stroke with a known source and non-cardioembolic stroke etiology. METHODS: Study patients were 540 consecutive ischemic stroke patients admitted to Helsinki University Hospital with primary end-point of recurrent stroke in a 21-month follow-up. Cox regression adjusting for CHA2DS2-VASc and anticoagulation estimated the risk of USEP on recurrent stroke. RESULTS: A total of 229 (42.4%) patients had a non-cardioembolic stroke etiology, 184 (34.1%) had a cardioembolic stroke with a known source, and 127 (23.5%) were classified as USEP. USEP patients had less diabetes and prior TIA, with more severe symptoms than the non-cardioembolic stroke cases. They were younger, had fewer comorbidities, and less severe symptoms than the cardioembolic stroke patients. Cumulative risk of recurrent stroke was 10.0% (95% CI 4.1%-15.9%) for USEP, 5.0% (1.1%-8.9%) for cardioembolic strokes, and 5.0% (3.0%-7.0%) for non- cardioembolic strokes (P = 0.089). USEP associated with a higher risk of recurrent stroke compared to non-cardioembolic strokes (hazard ratio 2.36, 95% CI 1.02-5.47; P = 0.046) and cardioembolic stroke with a known source (1.83, 1.07-3.14; P = 0.028). CONCLUSIONS: Despite their younger age and more favorable risk factor profile compared with other phenotypes, USEP exhibited a high risk of stroke recurrence.

MRI with cardiac pacing devices - safety in clinical practice.

OBJECTIVES: The aim of this study was to introduce a single centre "real life" experience of performing MRI examinations in clinical practice on patients with cardiac pacemaker systems. Additionally, we aimed to evaluate the safety of using a dedicated safety protocol for these patients. MATERIALS AND METHODS: We used a 1.5T MRI scanner to conduct 68 MRI scans of different body regions in patients with pacing systems. Of the cardiac devices, 32% were MR-conditional, whereas the remaining 68% were MR-unsafe. We recorded the functional parameters of the devices prior, immediately after, and approximately one month after the MRI scanning, and compared the device parameters to the baseline values. RESULTS: All MRI examinations were completed safely, and each device could be interrogated normally following the MRI. We observed no changes in the programmed parameters of the devices. For most of the participants, the distributions of the immediate and one-month changes in the device parameters were within 20% of the baseline values, although some changes approached clinically important thresholds. Furthermore, we observed no differences in the variable changes between MR-conditional and MR-unsafe pacing systems, or between scans of the thorax area and other scanned areas. CONCLUSION: MRI in patients with MR-conditional pacing systems and selected MR-unsafe systems could be performed safely under strict conditions in this study.

Minimizing ventricular pacing by a novel atrioventricular (AV) delay hysteresis algorithm in patients with intact or compromised intrinsic AV conduction and different atrial and ventricular lead locations.

PURPOSE: To investigate if an advanced AV search hysteresis (AVSH) algorithm, Ventricular Intrinsic Preference (VIP(™)), reduces the incidence of ventricular pacing (VP) in sinus node dysfunction (SND) with both intact and compromised AV conduction and with intermittent AV block regardless of the lead positions in the right atria and the ventricle. METHODS: Patients were classified as having intact AV (AVi) conduction if the PR interval was ≤ 210 ms on ECG and 1:1 AV conduction during atrial pacing up to 120 bpm with PR interval ≤ 350 ms. Otherwise the AV conduction was classified as compromised (AVc). Both AVi and AVc patients were randomized to VIP ON or OFF. VIP performed an intrinsic AV conduction search every 30 s for three consecutive atrial cycles with the extension of the sensed and paced AV (SAV/PAV) delays from basic values of 150/200 ms to 300/350 ms. Extended AV intervals were allowed for three cycles when VP occurred before returning to basic AV delays. The primary end-point was %VP at 12 months. RESULTS: Among 389 patients, 30.1% had intact and 69.9% had compromised AV conduction. The mean %VP at 12 months was 9.6% by VIP compared to 51.8% with standard AV settings in patients with AVi (P < 0.0001) and 28.0% versus 78.9% (P < 0.0001) with AVc. With VIP, excessive %VP among most used lead positions was not seen. Conversely, when VIP was off %VP was low only in patients who had leads in the RA septal-RV septal position (23.0%). CONCLUSIONS: VIP feature reduces VP both in patients with SND and with intermittent heart block regardless of the lead positions in the right atria and the ventricle.

Performance of atrial tachyarrhythmia-sensing algorithms in dual-chamber pacing using a fixed long AV delay in patients with sinus node dysfunction.

AIMS: The aim of the study was to evaluate the performance of pacemakers (PM) atrial tachyarrhythmia (AT)-sensing algorithms in sinus node dysfunction (SND) patients with DDDR pacing programmed with a fixed long atrioventricular (AV) delay. METHODS: In a prospective study, a total of 60 patients with SND were implanted with a dual-chamber PM with two different algorithms for detection of ATs. The study was done with a 3 month data collection period retrieved from the memory of PM and with a 7 day external Holter recording period. RESULTS: In 13 of 16 (81 %) patients whose Holter recording revealed the presence of ATs, episodes of AT sensing were retrieved from the PM memory with electrograms verifications, confirming that the devices had detected the ATs. Very short ATs seen in Holter recordings were missed by the PM with three patients. However, with all these patients after 3 months of follow up period, there were recognized periods of ATs by the PM. With ten (17 %) patients, there were intermittent periods of undersensing by the PM although continuous atrial fibrillation (AF) was seen in the Holter recording. Retrograde conduction caused false AT detection due to repetitive non-reentrant ventriculoatrial synchronous rhythm (RNRVAS) in six (25 %) of the 24 patients with retrograde conduction. CONCLUSIONS: Even with long AV delay, ATs can be accurately identified. However, transient undersensing of continuous AF and non-detection of very short AT episodes can still occur. Programming a long AV delay predisposes to RNRVAS which can cause false AT detection and symptoms in SND patients who have retrograde conduction.

Morphological analysis of sinus and retrograde atrial waves detected through a permanent pacemaker atrial lead.

AIMS: The main objective of this study was to characterize morphological differences between sinus and retrograde atrial waves. METHODS: We collected intracardiac atrial signals through a DDDR pacemaker to characterize their morphologies and discriminate retrograde from sinus atrial waves off-line. Intracardiac unipolar and bipolar signals were collected at an 800-Hz sampling rate through a 0.4-Hz high-pass filter. Sinus and retrograde atrial waves during ventricular pacing were recorded in the supine and upright positions. RESULTS: Eleven different form parameters (FPs) were applied to describe atrial wave morphology. Data from 14 patients were collected and analyzed. Atrial signals differed markedly between the two body postures. However, it was possible to discriminate retrograde from sinus atrial waves on the basis of at least one FP in 12 of 14 (86%) patients when unipolar and bipolar atrial signals recorded in both body postures were analyzed separately. When body postures were pooled together to mimic natural conditions, discrimination was successful in nine of 14 patients with either configuration of the atrial signal. CONCLUSIONS: The results indicate that retrograde atrial waves can be discriminated from sinus waves by using high sampling rate, digital signal processing, and specific FPs incorporated in these pacemakers.

[Modern pacemaker therapy]. / Nykyaikainen tahdistinhoito.

Automated functions of cardiac pacemakers correcting bradycardia provide the possibility to evaluate the utility of cardiac pacing and the patient's cardiac rhythm even over an extended period of time. Application of arrhythmia pacemaker therapy to the prevention of sudden death in high-risk patients has been started without limiting it to the prevention of recurrence of asystolia. Treatment of cardiac insufficiency with cardiac resynchronization therapy has established itself in a proportion of those having severe cardiac insufficiency. It relieves the insufficiency and extends the life span. Investigations have proved these therapies to be effective with respect to both results and costs.