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.

Coronary artery disease in congenital single coronary artery in adults: A Dutch case series.

AIM: To assess the current diagnostic and therapeutic management and the clinical implications of congenital single coronary artery (SCA) in adults. METHODS: We identified 15 patients with a SCA detected from four Dutch angiography centers in the period between 2010 and 2013. Symptomatic patients who underwent routine diagnostic coronary angiography (CAG) for suspected coronary artery disease and who incidentally were found to have isolated SCA were analyzed. RESULTS: Fifteen (7 females) with a mean age of 58.5 ± 13.78 years (range 43-86) had a SCA. Conventional CAG demonstrated congenital isolated SCA originating as a single ostium from the right sinus of Valsalva in 6 patients and originating from the left in 9 patients. Minimal to moderate coronary atherosclerotic changes were found in 4, and severe stenotic lesions in another 4 patients. Seven patients were free of coronary atherosclerosis. Runs of non-sustained ventricular tachycardia were documented in 2 patients, one of whom demonstrated transmural ischemic changes on presentation. Myocardial perfusion scintigraphic evidence of transmural myocardial ischemia was found in 1 patient due to kinking and squeezing of the SCA with an interarterial course between the aorta and pulmonary artery. Multi-slice computed tomography (MSCT) was helpful to delineate the course of the anomalous artery relative to the aorta and pulmonary artery. Percutaneous coronary intervention was successfully performed in 3 patients. Eight patients were managed medically. Arterial bypass graft was performed in 4 patients with the squeezed SCA. CONCLUSION: SCA may be associated with transient transmural myocardial ischemia and aborted sudden death in the absence of coronary atherosclerosis. The availability and sophistication of MSCT facilitates the delineation of the course of a SCA. We present a Dutch case series and review of the literature.

Cardiac involvement in Dutch patients with sarcoglycanopathy: a cross-sectional cohort and follow-up study.

INTRODUCTION: The aim of this study is to describe the frequency, nature, severity, and progression of cardiac abnormalities in a cohort of Dutch sarcoglycanopathy patients. METHODS: In this cross-sectional cohort study, patients were interviewed using a standardized questionnaire and assigned a functional score. Electrocardiography (ECG), echocardiography, and 24-h ECG were performed. RESULTS: Twenty-four patients with sarcoglycanopathy had a median age of 25 years (range, 8-59 years). Beta blockers were used by 13%, and 17% used angiotensin-converting enzyme inhibitors. ECG abnormalities were present in 5 (21%), and 4 (17%) fulfilled the criteria for dilated cardiomyopathy (DCM). There were no significant differences in median age or severity of disease between patients with or without DCM. Eleven patients were examined earlier. Median follow-up time was 10 years. Two of the 11 patients (18%) developed DCM during follow-up. CONCLUSIONS: Seventeen percent of the patients with sarcoglycanopathy were found to have dilated cardiomyopathy. We recommend biannual cardiac monitoring, including ECG and echocardiography.

Radiological and electrocardiographic characterization of right ventricular outflow tract pacing.

AIMS: The right ventricular outflow tract (RVOT) is used as an alternative pacing site, but its superiority to the RV apex remains to be established. This lack of proof may in part be explained by heterogeneity within the RVOT-paced group, due to poor definitions of the RVOT. The aim of the present study is to characterize the RVOT in terms of fluoroscopic and electrocardiographic parameters. METHODS AND RESULTS: One hundred and forty-three patients who underwent pacemaker implantation with a ventricular lead in the RVOT were included. Lead position was determined by fluoroscopy. The RVOT was divided into three areas: anterior, septal, and free wall (FW). On a 12-lead electrocardiogram (ECG) during forced ventricular pacing, QRS duration, configuration, and amplitude was determined. Lead position was judged to be anterior in 52 (36%), septal in 43 (30%), and FW in 48 (34%) patients, respectively. QRS duration is not significantly different between groups. QRS axis differs significantly between pacing sites (septal 79 ± 31°, anterior 60 ± 46°, FW 47 ± 38°, P < 0.05). QRS vector in lead I and QRS morphology and vector in lead aVL differ significantly between pacing sites. Precordial transition is earlier (towards V1) in septal pacing. CONCLUSIONS: This study demonstrates heterogeneity of pacing site and depolarization pattern within a cohort of patients paced form the RVOT. However, due to considerable overlap, we could not define clear cut-off point or devise flow-charts to match ECG and pacing site.

Clinical results of far-field R-wave reduction with a short tip-ring electrode.

BACKGROUND: Far-field R-wave (FFRW) sensing of the atrial lead of AAI or DDD pacemakers causes incorrect mode switches and remains a problem in patients with atrial arrhythmias in whom low voltage sensing is essential. We studied a pacing electrode with a short tip-ring distance (1.1 mm). We compared our findings with recordings from a conventional electrode with a larger tip-ring distance (10 mm). METHODS: Thirty-six consecutive patients with an indication for DDD pacing were implanted with the short tip-ring electrode. Another 23 patients received the conventional electrode. FFRW and P-wave amplitudes during pacing and intrinsic ventricular depolarization were measured at implantation. Measurements were repeated before hospital discharge and at follow-up between 10 and 14 days after implantation. RESULTS: P-wave amplitude was slightly smaller in the short tip-ring group (2.71+/-1.04 vs 3.17+/-1.30 mV in the conventional group, respectively, P=NS). All P-waves exceeded 1.2 mV. FFRW during pacing was 0.07+/-0.05 in the short tip-ring group and 0.54+/-0.32 mV in the conventional group (P<0.001). FFRW during intrinsic rhythm was 0.08+/-0.04 and 0.55+/-0.31 mV, respectively (P<0.001). The ratio between P-wave and FFRW was 48.6+/-27.2 in the short tip-ring group and 7.3+/-4.4 in the conventional group (P<0.001). FFRW and P-wave amplitudes did not change at hospital discharge or during follow-up. CONCLUSION: FFRW can be suppressed without compromising P-wave sensing by using a pacing electrode with a short tip-ring distance. Whether reduced FFRW amplitude results in clinical endpoints remains to be determined.

Routine follow-up after pacemaker implantation: frequency, pacemaker programming and professionals in charge.

AIMS: To describe current evidence of the frequency, contents, and involved professionals of the routine follow-up visits in patients who have received a pacemaker (PM). METHODS AND RESULTS: The multicentre FOLLOWPACE study prospectively collected data during implantation and follow-up of 1526 patients who received a PM for the first time. A total of 4914 follow-up visits were studied. Mean follow-up was 394 days with a mean of 3.2 visits per patient. At all follow-up visits, the battery condition was tested in >93%, the stimulation threshold in >91%, and sensing in >87%. The pacemaker parameters as stimulation and sensing thresholds, lead impedances, and percentages of pacing remained stable over time, but these values did depend on the lead location, lead fixation, and pulse duration. The majority of PM (re-)programming was performed during implantation and/or shortly before hospital discharge (50%). PM re-programming during follow-up was most frequently performed by the PM technician alone (95%). CONCLUSION: Crucial PM parameters are regularly checked. Re-programming of PM parameters declined during the first year after PM implantation. The majority of PM checks were carried out by the PM technician, indicating the major influence of the allied professional on the quality and safety of the pacing therapy.

Surgical treatment of bilateral aneurysmal coronary to pulmonary artery fistulas associated with severe atherosclerosis.

A 39-year-old diabetic patient with an old inferior wall infarction presented with disabling angina pectoris, despite medical treatment. Coronary angiography showed severe triple-vessel coronary artery disease, and bilateral coronary to pulmonary fistulas originating from the right coronary artery and the left anterior descending coronary artery. Both coronary artery saphenous vein bypass grafting and ligation of the fistulas was performed.

Cardiac and pulmonary investigations in Bethlem myopathy.

BACKGROUND: Bethlem myopathy is considered a relatively mild neuromuscular disorder without significant cardiac and respiratory involvement. OBJECTIVE: To investigate cardiac and respiratory involvement in Bethlem myopathy. DESIGN: Cross-sectional study. SETTING: University hospitals. Patients Fifty patients with Bethlem myopathy from 26 families. INTERVENTIONS: Cardiac examinations, including electrocardiography and echocardiography (n = 37) and pulmonary investigations (n = 43). Holter monitoring was performed in 16 patients. MAIN OUTCOME MEASURES: Cardiac and respiratory abnormalities. RESULTS: Several cardiac abnormalities were found that were considered unrelated to the muscular disorder. Seven (16%) of 43 patients had a forced vital capacity less than 70% of the predicted value. One of 2 patients with a forced vital capacity less than 50% was also receiving respiratory support. All patients with compromised respiratory function were still ambulatory, and we found no significant correlation between the severity of arm weakness and the severity of respiratory muscle involvement. CONCLUSIONS: There is no evidence of cardiac involvement in Bethlem myopathy. Respiratory failure is part of the clinical spectrum and can occur in ambulatory patients.

Verification of pacemaker automatic mode switching for the detection of atrial fibrillation and atrial tachycardia with Holter recording.

AIMS: Verification of the accuracy of onset, offset, and duration of automatic mode switching (AMS) of pacemakers compared with onset and end of atrial fibrillation (AF) or atrial tachycardia (AT). Correct pacemaker diagnosis of atrial tachyarrhythmias (AA) is indispensable for reliable automatic prevention and intervention algorithms of AA. METHODS AND RESULTS: Comparison was made of the AMS registration of the pacemaker-stored electrograms (EGMs) and the number and cumulative duration of these episodes with continuous 7-day Holter monitoring. Atrial sensitivity was kept at 0.5 mV and far field R-wave recognition in the atrial channel was excluded by blanking of this signal. Lead types were confined to leads with short-ring tip spacing (10-13.8 mm). During Holter monitoring, 18 of 57 included patients with standard reason for pacemaker implantation showed episodes of AF or AT. Cumulative duration of AF and AT from Holter was correctly interpreted by the pacemaker in 99.9% of the patients. All episodes of AF, as seen on the Holter recording, were recognized by the pacemaker (correlation 99.9%). During AF, multiple episodes of undersensing were detected. The number of AMS episodes was influenced by undersensing during AF. The influence of these short episodes of undersensing on the total duration of AF was trivial (cumulative duration of AF was 99.9% correct). In patients with AT without AF on Holter (n=7) and in contrast to the AF episodes, the cumulative AT duration did not correlate well (63%) with the Holter recordings. The number of AMS episodes in the setting of AT was influenced by the atrial tachycardia detection rate setting and the duration of the post-ventricular atrial blanking interval. CONCLUSION: The total duration of AF is correctly represented by the total duration of AMS and can be considered a reliable measure of total AF duration. AT duration was poorly correlated with AMS duration. The number of mode switches does not reflect the number of episodes of AF/AT. Increased memory capacity allowing the storing of all EGMs triggered by the initiation of AF/AT would be the ideal setting with which to optimize the diagnostic performance of pacemakers.

Occlusion of the coronary sinus: a complication of resynchronisation therapy for severe heart failure.

The finding of complete obstruction of the proximal coronary sinus after left ventricular (LV) lead extraction during LV lead replacement is uncommon. In our case, we used a large collateral branch of the middle cardiac vein as an alternative route to the postero-lateral region. We have termed this the 'collateral approach'.

A technique of lead insertion for low atrial septal pacing.

BACKGROUND: Pacing in the low right atrial septum (LAS) appears superior to right atrial appendage or free wall stimulation for the prevention of paroxysmal atrial fibrillation. However, insertion of active fixation lead in the low right atrial septal position is difficult and time consuming, inhibiting application of this pacing method in daily practice. METHODS: The technique of handling and positioning of a new "over the wire" lead system is presented with emphasis on electrocardiographic P wave pattern and fluoroscopic landmarks. RESULTS: The initial results demonstrate an acute implantation and short-term success of LAS pacing of >90% in the first 100 patients without major complications. Pacing thresholds at 3 and 6 months were fully comparable with that of the conventional atrial pacing, whereas impedance and atrial sensing signals were significantly higher at 3 and 6 months follow-up. CONCLUSION: These favorable initial results justify recommanding chronic LAS pacing with the active fixation atrial lead and providinge guidelines and fluoroscopic landmarks for the implantation. Insertion of the atrial active fixation lead positioned with the Locatortrade mark tool strongly supports the implantation procedure.

Electrocardiographic characteristics in low atrial septum pacing.

AIM: The aim of the study was to compare P-wave morphology and duration in pacing from the low right atrial septal wall and the high right atrial appendage (RAA). METHODS: The electrocardiogram (ECG) of 50 patients with low atrial septum (LAS) pacing and that of 50 patients with RAA pacing were compared with their electrocardiogram during sinus rhythm. RESULTS: In the frontal plane, patients with LAS pacing showed a superior P-wave axis between -60 degrees and -90 degrees . In all patients with RAA pacing, a P-wave axis between 0 degrees and +90 degrees was observed as in sinus rhythm. In the horizontal plane, all patients with LAS pacing had an anterior P-wave axis between +90 degrees and +210 degrees , whereas all patients with RAA pacing had a posterior P-wave axis between -30 degrees and -90 degrees . The terminal part of biphasic P waves in lead V 1 in LAS pacing was always positive, a pattern that was never observed in P waves of sinus origin or in RAA pacing. P-wave duration was longer with RAA pacing compared with LAS pacing (115 +/- 19 vs 80 +/- 14 milliseconds [ P < .01]). CONCLUSION: The total atrial activation time during LAS pacing is shorter than that during RAA pacing. The electrical atrial activation sequences in LAS pacing and RAA pacing are significantly different. The morphology of biphasic P waves in lead V1 during LAS pacing suggests that the initial part of activation occurs in the left atrium and the terminal part in the right atrium.

Electrical characteristics of low atrial septum pacing compared with right atrial appendage pacing.

AIM: The study was designed to compare the electrical characteristics of atrial leads placed in the low atrial septum (LAS) with those placed in the right atrial appendage (RAA) associated with dual chamber pacing. METHODS: In 86 patients an active-fixation (St. Jude Medical's Tendril DX model 1388T) atrial lead was positioned in RAA and in 86 patients the same model atrial lead was placed in the LAS. Pacing thresholds, sensing thresholds, impedances and the Far Field paced R-Wave (FFRW) amplitude and timing were compared at 6 weeks and at 3 and 6 months. RESULTS: The pacing threshold did not differ between groups. Sensed voltage of the P-wave was higher in the LAS compared with the RAA at 3 and 6 months (P=0.004). Impedance was higher in the LAS at 6 weeks and 3 months (P=0.002) but this difference was no longer significant at 6 months (P=0.05). The atrial sensed FFRW voltage was significantly higher in the LAS position compared with the RAA at 3 and 6 months follow-up (P=0.0002). FFRW voltage>1 mV was seen in 87% of the RAA pacing group and in 94% of the LAS pacing group (P=ns). The time between the ventricular pacing stimulus and the sensed FFRW in the atrium, (V spike-FFRW) in RAA was longer than in LAS at all follow-up measurements (P=0.006). CONCLUSIONS: The electrical characteristics of LAS pacing makes this alternative position in the atrium safe and feasible. Though statistical differences were found in P-wave sensing (LAS higher voltage than in the RAA) and FFRW sensing was higher in the LAS compared with the RAA this did not interfere with the clinical applicability of the LAS as alternative pacing site.

Meta-analysis of clinical characteristics of 299 carriers of LMNA gene mutations: do lamin A/C mutations portend a high risk of sudden death?

This study evaluated common clinical characteristics of patients with lamin A/C gene mutations that cause either isolated dilated cardiomyopathy or dilated cardiomyopathy in association with skeletal muscular dystrophy. We pooled clinical data of all published carriers of lamin A/C gene mutations as cause of skeletal and/or cardiac muscle disease and reviewed ECG findings. Cardiac dysrhythmias were reported in 92% of patients after the age of 30 years; heart failure was reported in 64% after the age of 50. Sudden death was the most frequently reported mode of death (46%) in both the cardiac and the neuromuscular phenotype. Carriers of lamin A/C gene mutations often received a pacemaker (28%). However, this intervention did not alter the rate of sudden death. Review of the ECG findings typically showed a low amplitude P wave and prolongation of the PR interval with a narrow QRS complex. This meta-analysis suggests that cardiomyopathy due to lamin A/C gene mutations portends a high risk of sudden death, and that this risk does not differ between subjects with predominantly cardiac or neuromuscular disease. This implies then that all carriers of a lamin A/C gene mutation need to be carefully screened with particular emphasis also on tachyarrhythmias. Prospective studies are needed to evaluate risk stratification and proper treatment strategies.

Understanding capture detection.

Automatic capture detection systems are currently available in several cardiac pacing devices. All current systems use low-polarization electrodes and no beat to beat detection system is available for all types of electrodes. In addition the success ratio for currently available systems is not always 100%. Failure to detect capture reliably is often related to the behaviour of the electrode-tissue interface under different circumstances. Pacemaker electrodes can be considered electrochemical cells with complicated characteristics depending on time, temperature and electrical charge. This electrochemical cell is disturbed when a charge is transferred across the electrode-tissue interface during pacing. Several measures can be taken in order to minimise this disturbance or pace polarization artefact (PPA) including the use of high active surface area electrodes and application of tri-phasic pacing pulses. Another factor influencing detection of evoked potentials is the input circuit of the pacemaker affecting the PPA and the evoked response. Positive PPAs can be falsely interpreted as evoked potentials due to the undershoot of the second order filters applied in modern cardiac pacemakers. This paper explains the behaviour of the interface between the electrode and the cardiac tissue in combination with the pacemaker output circuits and input amplifiers under different circumstances.