Anteroseptal basal right ventricular entrainment is simple and superior to apical entrainment in identifying mechanism of supraventricular tachycardia

Background

Differentiation between atrioventricular nodal reentry tachycardia (AVNRT) and atrioventricular reentrant tachycardia (AVRT) can be sometimes challenging. Apical right ventricular (RV) entrainment can help in differentiation; however, it has some fallacies. We thought to compare the accuracy of anteroseptal basal RV entrainment to RV apical entrainment in identifying the mechanism of supraventricular tachycardia (SVT).

Methods

Forty-two consecutive patients with SVT who underwent catheter ablation were prospectively studied. Apical RV entrainment was performed initially followed by basal entrainment from the anteroseptal basal RV avoiding His or atrial capture. Postpacing interval (PPI), PPI–tachycardia cycle length (TCL), corrected PPI-TCL, and stimulus–atrial minus ventricular–atrial (VA) intervals were measured.

Results

Entrainment was achieved from both sites of RV in 34 patients (ten men; mean age 42?±?15 years), 20 with typical AVNRT, 1 with atypical AVNRT, and 13 with AVRT (eight left sided, four right sided, and one septal accessory pathways). PPI-TCL, corrected PPI (cPPI)-TCL, and stimulus–atrial–VA intervals were significantly longer with basal entrainment in AVNRT (171?±?30 vs. 153?±?22 ms (p?=?0.003), 148?±?21 vs. 131?±?20 ms (p?=?0.002), and 145?±?17 vs. 136?±?15 ms (p?=?0.005), respectively). Receiver-operating characteristic curves showed higher AUC for the above parameters with basal entrainment compared to apical entrainment. Cutoff values of basal PPI-TCL of >110 ms and cPPI-TCL of >95 ms had better sensitivities (100 % for both vs. 95 and 90 %, respectively, for apical values) and specificities (85 and 92 % vs. 77 and 92 %, respectively) for diagnosis of AVNRT.

Conclusion

Basal RV entrainment from the anteroseptal basal RV is a simple maneuver that is superior to apical ventricular entrainment in identifying the mechanism of SVT.     

Comparison of left atrial electrophysiologic abnormalities during sinus rhythm in patients with different type of atrial fibrillation

Objective

The purpose of this study is to explore the left atrium (LA) electrophysiologic abnormalities in atrial fibrillation (AF) patients detected during sinus rhythm and to determine the relationship between the type of AF and the electrophysiologic substrate in the LA.

Methods

Eighty patients with AF (30 paroxysmal AF, 22 persistent AF, and 28 long-standing AF) and 20 age- and sex-matched patients with left-sided accessory pathway were prospectively studied. High-density three-dimensional electroanatomic mapping was performed during sinus rhythm in LA, which was divided into six segments for regional analysis. Mean bipolar voltage, low voltage zone (LVZ) distribution, LA activation time, and electrogram complexity were assessed.

Results

The LA mean voltage was 3.67?±?0.68 mV in no AF group, 2.16?±?0.63 mV in the paroxysmal, 1.81?±?0.36 mV in the persistent, and 1.48?±?0.34 mV in the long-standing AF patients (P?<?0.001). The total LA activation time was 75.3?±?5.4 ms in no AF, 89.7?±?12.3 ms in paroxysmal AF, 104.9?±?6.1 ms in persistent AF, and 115.6?±?12.1 ms in the long-standing AF patients, respectively (P?<?0.001). With the progression of AF, there was a higher incidence of LVZ detection and increased prevalence of complex electrograms with 95 % of complex electrograms in areas with the bipolar voltage ≤?1.3 mV in persistent and long-standing AF patients.

Conclusion

Patients with AF have abnormal electrophysiologic substrate in sinus rhythm characterized by lower mean bipolar voltage, more prevalent complex electrograms, and longer LA activation time. This substrate progresses parallel to progression of AF type.     

Electrophysiologic features of protected channels in late postinfarction patients with and without spontaneous ventricular tachycardia

Purpose

Protected channels of surviving myocytes in late postinfarction ventricular scar predispose to ventricular tachycardia (VT). However, only a few patients develop VT spontaneously. We studied differences in electric remodeling and protected channels in late postinfarction patients with and without spontaneous VT.

Methods

Patients with ischemic cardiomyopathy (ICM) with recurrent sustained monomorphic VT (n?=?22) were compared with stable ICM patients without spontaneous VT (control group; n?=?5). Left ventricular mapping was performed with a 20-pole catheter. Detailed pace mapping was used to identify channels of protected conduction, and confirmed, when feasible, by entrainment. Anatomical and electrophysiological properties of VT channels and non-VT channels in VT patients and channels in controls were evaluated.

Results

Seventy-three (median 3) VTs were inducible in VT patients compared to two (median 0) in controls. The VT channels in VT patients (n?=?57, 3?±?1 per patient) were lengthier (mean?±?SEM 53?±?5 vs. 33?±?4 vs. 24?±?8 mm), had longer S-QRS (73?±?4 vs. 63?±?3 vs. 44?±?8 ms), longer conduction time (103?±?13 vs. 33?±?4 vs. 24?±?8 ms), and slower conduction velocity (CV) (0.85?±?0.21 vs. 1.39?±?0.20 vs. 1.31?±?0.41 m/s) than non-VT channels in VT patients (n?=?183, 8?±?6 per patient) (p?≤?0.01) and channels in controls (n?=?46, 9?±?8 per patient) (p?≤?0.01). Additionally, non-VT channels in VT patients had longer S-QRS (p?=?0.02); however, they were similar in length, conduction time, and CV compared to channels in controls.

Conclusions

Channels supporting VT are lengthier, with longer conduction times and slower CV compared to channels in patients without spontaneous VT. These observations may explain why some ICM patients have spontaneous VT and others do not.

     

Electrocardiographic characteristics for predicting idiopathic right ventricular outflow tract premature ventricular complex-induced cardiomyopathy

Purpose

In spite of several proposed predictors for premature ventricular complex (PVC)-induced cardiomyopathy (PVC-CMP), the specific ECG features of idiopathic right ventricular outflow tract (RVOT) PVC-CMP remain unknown.

Methods

A total of 130 patients (49 males, mean age 44 years) with symptomatic and drug-refractory idiopathic RVOT PVCs undergoing radiofrequency catheter ablation (RFCA) were enrolled. The patients were categorized into two groups, including those with and without RVOT PVC-CMP (left ventricular ejection fraction (LVEF) <?50%, n?=?25 and LVEF ≥?50%, n?=?105, respectively). The 12-lead PVC morphologies were assessed.

Results

Patients with RVOT PVC-CMP had a lower LVEF (42?±?5% vs. 60?±?7%, P?<?0.01) and higher PVC burden (24?±?14% vs. 15?±?11%, P?=?0.02) when compared to patients without RVOT PVC-CMP. The PVC features in those with PVC-CMP displayed a significantly wider QRS duration (143?±?14 ms vs. 132?±?17 ms, P?<?0.01) and higher peak deflection index (PDI; 0.60?±?0.07 vs. 0.55?±?0.08, P?<?0.01). A multivariate analysis demonstrated that the QRS duration (odds ratio (OR) 1.130, 95% confidence interval (CI) 1.020–1.253, P?=?0.02) and PDI (OR 1.240, 95% CI 1.004–1.532, P?=?0.04) were independently associated with RVOT PVC-CMP. Based on the receiver-operating characteristic analysis, a QRS duration >?139 ms and PDI >?0.57 could predict RVOT PVC-CMP (area under the curve (AUC) 0.710 and AUC 0.690, respectively). The elimination and suppression of PVCs by RFCA resulted in the recovery of the LVEF in RVOT PVC-CMP.

Conclusions

The ECG parameters, including a wider QRS duration and higher PDI, could predict the development of RVOT PVC-CMP, which could be effectively treated by RFCA.

     

Use of a closed loop irrigated catheter in epicardial ablation of ventricular tachycardia

Purpose

Catheter ablation of ventricular tachycardia (VT) often requires a combined epicardial and endocardial approach. An open irrigated catheter for epicardial ablation of ventricular tachycardia is commonly used. However, this can be associated with problems of fluid accumulation in the pericardial space necessitating repeated aspirations and interfering with catheter–tissue contact. A closed loop irrigated catheter can be a viable alternative to overcome these problems. We report our first three cases of epicardial VT ablation using a closed loop irrigated ablation catheter (Chilli II, Boston Scientific).

Methods

Catheter ablation of ventricular tachycardia was performed via epicardial and endocardial approaches using a closed loop irrigated ablation catheter (Chilli II, Boston Scientific) and using 3-D mapping with EnSite/NavX system. Patients were routinely followed up after the catheter ablation procedure in clinic for any recurrence of ventricular arrhythmia.

Results

We report our first three cases of epicardial VT ablation using a closed loop irrigated ablation catheter. Power delivery was adequate with mean power of 15.2?±?2.8, 31.1?±?3.8, and 25.0?±?3.3 W, respectively, in the three patients. No impedance rises were noted during the lesion formation. There was no recurrence of VT in any of the patients after 3 months of follow-up.

Conclusions

To our knowledge, we report the first case series of epicardial VT ablation using a closed loop irrigated catheter and the EnSite/NavX mapping system. The advantages of closed irrigation, especially in conjunction with impedance-based anatomical mapping, warrant further study of its efficacy in catheter ablation from the pericardial space.     

Maternal insulin sensitivity is associated with oral glucose-induced changes in fetal brain activity

Aims/hypothesis

Fetal programming plays an important role in the pathogenesis of type 2 diabetes. The aim of the present study was to investigate whether maternal metabolic changes during OGTT influence fetal brain activity.

Methods

Thirteen healthy pregnant women underwent an OGTT (75 g). Insulin sensitivity was determined by glucose and insulin measurements at 0, 60 and 120 min. At each time point, fetal auditory evoked fields were recorded with a fetal magnetoencephalographic device and response latencies were determined.

Results

Maternal insulin increased from a fasting level of 67?±?25 pmol/l (mean ± SD) to 918?±?492 pmol/l 60 min after glucose ingestion and glucose levels increased from 4.4?±?0.3 to 7.4?±?1.1 mmol/l. Over the same time period, fetal response latencies decreased from 297?±?99 to 235?±?84 ms (p?=?0.01) and then remained stable until 120 min (235?±?84 vs 251?±?91 ms, p?=?0.39). There was a negative correlation between maternal insulin sensitivity and fetal response latencies 60 min after glucose ingestion (r?=?0.68, p?=?0.02). After a median split of the group based on maternal insulin sensitivity, fetuses of insulin-resistant mothers showed a slower response to auditory stimuli (283?±?79 ms) than those of insulin-sensitive mothers (178?±?46 ms, p?=?0.03).

Conclusions/interpretation

Lower maternal insulin sensitivity is associated with slower fetal brain responses. These findings provide the first evidence of a direct effect of maternal metabolism on fetal brain activity and suggest that central insulin resistance may be programmed during fetal development.     

Repolarization in perfused myocardium predicts reperfusion ventricular tachyarrhythmias

Background

Aim of the study was to find out which myocardial repolarization parameters predict reperfusion ventricular tachycardia and fibrillation (VT/VF) and determine how these parameters express in ECG.

Right ventricular geometry and mechanics in patients with obstructive sleep apnea living at high altitude

Purpose

Repetitive obstruction of larynx during sleep can lead to daytime pulmonary hypertension and alterations in right ventricular morphology and function in a small fraction of obstructive sleep apnea syndrome (OSAS) patients. Environmental effects, particularly high altitude, can modify the effects of OSAS on pulmonary circulation, since altitude-related hypoxia is related with pulmonary vasoconstriction. This potential interaction, however, was not investigated in previous studies.

Methods

A total of 41 newly diagnosed OSAS patients were included in this study after pre-enrolment screening. Two-dimensional, three-dimensional, and Doppler echocardiographic data were collected after polysomnographic verification of OSAS. Three-dimensional echocardiograms were analyzed to calculate right ventricular volumes, volume indices, and ejection fraction.

Results

Systolic pulmonary artery pressure (38.35?±?8.60 vs. 30.94?±?6.47 mmHg; p?=?0.002), pulmonary acceleration time (118.36?±?16.36 vs. 103.13?±?18.42 ms; p?=?0.001), right ventricle (RV) end-diastolic volume index (48.15?±?11.48 vs. 41.48?±?6.45 ml; p?=?0.009), and RV end-systolic volume index (26.50?±?8.11 vs. 22.15?±?3.85; p?=?0.01) were significantly higher in OSAS patients, with similar RV ejection fraction (EF) between groups. No significant differences were noted in other two-dimensional, Doppler or speckle-tracking strain, measurements. Both RVEF and pulmonary acceleration time were predictors of disease severity.

Conclusions

A greater degree of RV structural remodeling and higher systolic pulmonary pressure were observed in OSAS patients living at high altitude compared to healthy highlanders. The reversibility of these alterations with treatment remains to be studied.

     

Characteristics of idiopathic ventricular tachycardia originating above the pulmonary valve

Panoptic studies of ventricular tachycardia (VT) originating above the pulmonary valve are scarce. The purpose of this study is to clarify the characteristic of idiopathic VT arising above pulmonary valve. We analyzed 15 consecutive patients with idiopathic VT that was successfully abolished by catheter ablation at the right ventricular outflow tract (RVOT-VT, n = 11) and above the pulmonary valve (PA-VT, n = 4). Incidence of syncope was higher in PA-VT than RVOT-VT (100 vs 27 %, P < 0.05) and polymorphic VT was also more prevalent in PA-VT (75 vs 0 %, P < 0.05). The coupling interval (315 ± 29 vs 449 ± 32 ms, mean ± SE) at the onset of VT and minimum cycle length (CL) (192 ± 13 vs 344 ± 37 ms) during VT were shorter in PA-VT (both P < 0.05). Among 12-lead ECG parameters, only R-wave amplitude in lead II was different between groups (2.05 ± 0.17 mV in PA-VT vs 1.44 ± 0.05 mV in RVOT-VT, P < 0.005). At the successful ablation site, the activation time from the onset of QRS complex did not differ between groups (?37 ± 3 vs ?31 ± 4, P = 0.405), whereas, the amplitude of intracardiac electrograms was significantly lower in PA-VT (0.83 ± 0.38 mV vs 2.39 ± 0.36 mV, P < 0.05). Although the number of patients in this study is limited, VT originating above the pulmonary valve demonstrated rapid excitation and often degenerated into polymorphic VT, suggesting its malignant electrophysiological characteristics.     

Impact of left atrial appendage ridge ablation on the complex fractionated electrograms in persistent atrial fibrillation

Background

The left atrial appendage (LAA) is a possible key contributor to the maintenance of persistent atrial fibrillation (PsAF). The effect of LAA ostial ablation on global left atrial higher-frequency sources remains unclear.

Methods

Complex fractionated electrograms (CFEs) and dominant frequency (DF) maps acquired with a NavX system in 58 PsAF patients were enrolled and examined before and after LAA posterior ridge ablation, which followed a stepwise linear ablation.

Results

High-density left atrial mapping identified continuous CFE sites in 50 % and high-DFs (≥8 Hz) in 53 % of patients at the LAA posterior ridge. In 44 patients in whom AF persisted despite pulmonary vein isolation (PVI) and linear ablation, LAA ablation significantly increased the mean CFE cycle length from 98?±?29 to 108?±?30 ms (P?P?90 mL/m²) (median 0 vs 4.8 %; P?P?Conclusion These findings suggested that an approach incorporating an LAA posterior ridge ablation was effective in modifying higher-frequency sources in the global LA in PsAF patients, but a lesser effect was documented in patients with electroanatomical remodeling of the LA.     

P wave duration and dispersion in Holter electrocardiography of patients with obstructive sleep apnea

Purpose

The underlying mechanisms of the association between obstructive sleep apnea (OSA) and atrial fibrillation (AF) remained unclear. We investigated P wave parameters as indicators of atrial conduction status among OSA patients.

Methods

We studied 42 untreated OSA patients, categorized into mild (6), moderate (18), and severe (18) OSA based on the apnea/hypopnea index (AHI) and 18 healthy controls. Twenty-four-hour Holter electrocardiography was applied to measure P wave parameters including P wave duration and P wave dispersion; difference between the maximum (P-max) and minimum (P-min) measured P wave duration.

Results

Mean P wave duration ranged from 110.2?±?9.3 ms in mild OSA patients to 121.1?±?15.4 ms in severe OSA patients and was 113.4?±?10.0 ms in controls with no significant difference among the groups, P?=?0.281. P wave dispersion and P-max were significantly longer in those with moderate OSA (68.0?±?9.3 and 154.2?±?9.3 ms) and those with severe OSA (71.6?±?13.7 and 157.2?±?13.3 ms) than controls (52.6?±?15.3 and 142.1?±?15.4 ms), P?r?=?0.407, P?=?0.012) and P wave dispersion (r?=?0.431, P?=?0.008). With linear regression analysis controlling for age, gender, and BMI, the AHI was independently associated with P wave dispersion (β?=?0.482, P?=?0.002).

Conclusions

Using Holter monitoring for measurement of P wave parameters, this study showed an association of OSA with prolonged P-max and P wave dispersion. These results indicate that patients with OSA have disturbances in atrial conduction associated with OSA severity. Repeating this study in a larger sample of patients is warranted.     

Correlations Between Small Airway Function,Ventilation Distribution,and Functional Exercise Capacity in COPD Patients

Background

Interest in using the nitrogen single-breath washout (N₂SBW) test to measure ventilation inhomogeneity and small airway function in COPD patients has grown in recent years. Our aim was to assess the correlation of the measures obtained by the N₂SBW test and other pulmonary function parameters with the six-minute walk distance (6MWD), the degree of dyspnea score, and health status in COPD patients.

Methods

In this cross-sectional study, 31 patients with COPD were subjected to the N₂SBW test, spirometry, whole-body plethysmography, carbon monoxide diffusing capacity measurement, the six-minute walk test, the modified Medical Research Council (mMRC) scale, and the COPD Assessment Test (CAT).

Results

We found a strong correlation between the 6MWD and the phase III slope of the nitrogen single-breath washout (Phase III slope_N2SBW) (r = ?0.796; p = 0.0001). We found moderate correlations between the 6MWD and the residual volume (RV) (r = ?0.651; p = 0.0001) and RV/total lung capacity (RV/TLC) (r = ?0.600; p = 0.0004). We also found moderate correlations between the CAT score and Phase III slope_N2SBW (r = 0.728; p = 0.0001), RV (r = 0.646; p = 0.0001) and RV/TLC (r = 0.603; p = 0.0003). There was a significant difference between the mMRC grades for the following variables: Phase III slope_N2SBW (p = 0.0001), RV (p = 0.0001), and smoking history (p = 0.008). Multivariate analysis showed that Phase III slope_N2SBW was the only independent predictor of the 6MWD (R ²  = 0.703; p = 0.0001), CAT score (R ²  = 0.586; p = 0.0001), and mMRC scale (relative risk = 1.14; p = 0.0001).

Conclusions

In patients with COPD, our findings suggest that the ventilation inhomogeneity impacts the functional exercise capacity, the degree of dyspnea, and health status.     

Right ventricular longitudinal deformation parameters and exercise capacity

Objective

Chronic thromboembolic pulmonary hypertension (CTEPH) is a progressive disease characterized by increased pulmonary vascular resistance resulting in pulmonary hypertension and right heart failure. The six-minute walk test (6MWT) distance is associated with the prognosis of CTEPH patients. Speckle tracking echocardiography (STE) is a reliable method for determining ventricular function. The aim of this study was to assess and compare the right ventricular (RV) function of CTEPH patients according to their 6MWT distances.

Methods

Forty-nine consecutive CTEPH patients (mean age, 50?±?16 years; 22 male) who were referred to our center for pulmonary thromboendarterectomy (PTE) were included in the study. All patients underwent the 6MWT and right heart catheterization (RHC). Standard echocardiography and STE were performed on all patients before PTE. Patients were divided into two groups based on their 6MWT distance being less or more than 300 m.

Results

Patients with a shorter 6MWT distance had a significantly larger RV, while they had a significantly lower RV fractional area change and higher myocardial performance index suggesting impaired RV function. Both RV basal–lateral strain and strain rate measures were significantly lower in patients with shorter 6MWT distances than those with longer 6MWT distances. Similarly, they had lower RV basal–septal, mid-lateral, and global strain measures. 6MWT distances were correlated with RV basal–lateral and mid-lateral strain measures (r?=?0.349, p?=?0.025 and r?=?0.415, p?=?0.008, respectively).

Conclusion

Our data suggest that RV myocardial deformation parameters are associated with 6MWT distances. Determination of RV dysfunction by STE may be helpful in identifying patients with a poor prognosis.     

Catheter ablation for atrial fibrillation results in greater improvement in cardiac function in patients with low versus normal left ventricular ejection fraction

Purpose

It is still unknown whether left ventricular ejection fraction (LVEF) might affect the magnitude of improvement after atrial fibrillation (AF) ablation on cardiac function in persistent or longstanding persistent AF (CAF) patients.

Method

We performed echocardiography in 35 patients with CAF before and after catheter ablation (CA). Patients were stratified by LVEF into two groups prior to CA—normal LVEF (≥50 % LVEF, N group, n?=?24) and a low LVEF group (<50 % LVEF, L group, n?=?11). Patients were followed at 1 month, 3 months, 6 months, 1 year, and 2 years after ablation.

Results

After 15.8?±?7.4 months follow-up, the L group showed greater improvement in LVEF and left atrial ejection fraction (LAEF; N group vs L group: LVEF difference (%), 5?±8 vs 20±?13, p?<?0.01; LAEF difference (%), 11?±?12 vs 21?±?10, p?<?0.05). LA maximal volume and E/e′ showed the same tendency after ablation, although the extent of improvement was not statistically significant. Both groups showed almost the same time course of improvement up to 2 years, although the L group showed earlier recovery in LVEF.

Conclusion

The greater improvement in several cardiac functions was seen in patients with greater LV dysfunction, after the CA for CAF.     

Conduction characteristics in atrial fibrillation

Background

Atrial fibrillation (AF) is one of the most common arrhythmias observed in clinical practice. The frequency of AF is increased in patients with impaired interatrial conduction. We aimed to investigate whether tissue Doppler echocardiography could be used for the evaluation of atrial conduction characteristics instead of an electrophysiological study, and to examine the predictive accuracy of tissue Doppler echocardiography for the inducibility of sustained AF.

Methods

We enrolled 86 consecutive patients who underwent an electrophysiological study. We performed electrocardiographic P wave dispersion, M-mode, two-dimensional, Doppler, and tissue Doppler echocardiography as well as an electrophysiological study (EPS) to evaluate the intra- and interatrial conduction times. We tried to induce AF, and the patients were categorized according to the inducibility of sustained (>?120 s) AF.

Results

We found a good correlation between intra-left atrial conduction time detected by tissue Doppler echocardiography (ILCT-echo) and by EPS (ILCT-eps; r?=?0.744, p?<?0.001), and a weak correlation between interatrial conduction times (IACT-echo and IACT-eps, r?=?0.396, p?<?0.001). In patients with inducible sustained AF, P wave dispersion (46?±?19 ms vs. 27?±?18, p?<?0.001), ILCT-echo (29?±?10 ms vs. 17?±?7 ms, p?<?0.001), and IACT-eps (47?±?11 ms vs. 36?±?13 ms, p?<?0.001) were found to be higher than those of the noninducible/nonsustained AF group. These three parameters were independent predictors of the inducibility of sustained AF.

Conclusion

We demonstrated that ILCT-echo could be used instead of ILCT-eps for the evaluation of left atrial conduction characteristics. We also showed that ILCT-eps could be a valuable parameter for predicting the development of long-lasting AF.     

Cardiac conduction disturbances and differential effects on atrial and ventricular electrophysiological properties in desmin deficient mice

Purpose

Desmin mutations in humans cause desmin-related cardiomyopathy, resulting in heart failure, atrial and ventricular arrhythmias, and sudden cardiac death. The intermediate filament desmin is strongly expressed in striated muscle cells and in Purkinje fibers of the ventricular conduction system. The aim of the present study was to characterize electrophysiological cardiac properties in a desmin-deficient mouse model.

Methods

The impact of desmin deficiency on cardiac electrophysiological characteristics was examined in the present study. In vivo electrophysiological studies were carried out in 29 adult desmin deficient (Des^?/?) and 19 wild-type (Des^+/+) mice. Additionally, epicardial activation mapping was performed in Langendorff-perfused hearts.

Results

Intracardiac electrograms showed no significant differences in AV, AH, and HV intervals. Functional testing revealed equal AV-nodal refractory periods, sinus-node recovery times, and Wenckebach points. However, compared to the wild-type situation, Des^?/? mice were found to have a significantly reduced atrial (23.6?±?10.3 ms vs. 31.8?±?12.5 ms; p?=?0.045), but prolonged ventricular refractory period (33.0?±?8.7 ms vs. 26.7?±?6.5 ms; p?=?0.009). The probability of induction of atrial fibrillation was significantly higher in Des^?/? mice (Des^?/?: 38% vs. Des^+/+: 27%; p?=?0.0255), while ventricular tachycardias significantly were reduced (Des^?/?: 7% vs. Des^+/+: 21%; p?<?0.0001). Epicardial activation mapping showed slowing of conduction in the ventricles of Des^?/? mice.

Conclusions

Des^?/? mice exhibit reduced atrial but prolonged ventricular refractory periods and ventricular conduction slowing, accompanied by enhanced inducibility of atrial fibrillation and diminished susceptibility to ventricular arrhythmias. Desmin deficiency does not result in electrophysiological changes present in human desminopathies, suggesting that functional alterations rather than loss of desmin cause the cardiac alterations in these patients.     

Reverse atrial electrical remodelling induced by continuous positive airway pressure in patients with severe obstructive sleep apnoea

Background

Obstructive sleep apnoea (OSA) is associated with cardiovascular morbidity and mortality, including atrial arrhythmias. Continuous positive airway pressure (CPAP) is the gold standard treatment for OSA; its impact on atrial electrical remodelling has not been fully investigated. Signal-averaged p-wave (SAPW) duration is an accepted marker for atrial electrical remodelling.

Objective

The objective of this study is to determine whether CPAP induces reverse atrial electrical remodelling in patients with severe OSA.

Methods

Consecutive patients attending the Sleep Disorder Clinic at Kingston General Hospital underwent full polysomnography. OSA-negative controls and severe OSA were defined as apnoea–hypopnea index (AHI)?<?5 events/hour and AHI?≥?30 events/hour, respectively. SAPW duration was determined at baseline and after 4–6 weeks of CPAP in severe OSA patients or without intervention controls.

Results

Nineteen severe OSA patients and 10 controls were included in the analysis. Mean AHI and minimum oxygen saturation were 41.4?±?10.1 events/hour and 80.5?±?6.5 % in severe OSA patients and 2.8?±?1.2 events/hour and 91.4?±?2.1 % in controls. At baseline, severe OSA patients had a greater SAPW duration than controls (131.9?±?10.4 vs 122.8?±?10.5 ms; p?=?0.02). After CPAP, there was a significant reduction of SAPW duration in severe OSA patients (131.9?±?10.4 to 126.2?±?8.8 ms; p?<?0.001), while SAPW duration did not change after 4–6 weeks in controls.

Conclusion

CPAP induced reverse atrial electrical remodelling in patients with severe OSA as represented by a significant reduction in SAPW duration.     

Development of mitral and tricuspid regurgitation in right ventricular apex versus right ventricular outflow tract pacing

Purpose

This study aimed at comparing the development of tricuspid and mitral regurgitation between the right ventricular outflow tract (RVOT) and right ventricular apex (RVA) pacing.

Methods

We prospectively enrolled 164 patients for permanent pacemaker implantation due to sick sinus syndrome or atrioventricular block and randomly divided them into two equal groups to receive either RVOT or RVA pacing. Patients with heart failure or valvular disease were excluded. The post-procedural echocardiographic evaluations were performed 1 year after the pre-procedural echocardiography, and the results were compared with respect to the development of mitral and tricuspid regurgitation and probable changes in the ejection fraction (EF).

Results

Age, gender, pacing mode, and baseline cardiac rhythm did not significantly differ between the RVOT and RVA pacing groups. The incidence of mitral regurgitation was significantly higher in the RVA group (p?=?0.03), but the incidence of tricuspid regurgitation was similar in both groups. There was a trend toward less tricuspid regurgitation in the RVOT group; however, it was not statistically significant. The mean EF was not significantly different between the study groups.

Conclusion

It seems that the incidence of mitral regurgitation in RVA pacing is significantly higher than that in RVOT pacing. The formation of tricuspid regurgitation needs to be discussed in the future.

Clinical trial registration number

IRCT201103146061N1     

Relationship between fragmented QRS complexes and left ventricular systolic and diastolic functions

Background

Fragmented QRS complexes (fQRS) have been associated with increased morbidity and mortality, sudden cardiac death, and recurrent cardiovascular events. The association between left ventricular systolic and diastolic functions and presence of fragmented QRS has not been comprehensively studied to date. We tested the hypothesis that the presence of fragmented QRS is associated with left ventricular systolic and diastolic dysfunction.

Methods

The study included 259 patients who were consecutively admitted to our outpatient clinic for cardiovascular risk factor management. Extensive echocardiographic parameters were obtained from all patients and these were compared with the presence and number of fQRS.

Results

Patients with fQRS were of older age (58?±?12 vs. 55?±?13 years, p?=?0.03) and had prolonged QRS time (105?±?12 vs. 93?±?10 ms, p?<?0.001) and a higher rate of Q waves on ECG (36% vs. 11%, p?<?0.001). In addition, they had worse systolic (lower LVEF%, 44?±?17 vs. 61?±?12, p?<?0.001) and diastolic functions (DT, 177?±?77 vs. 211?±?59 ms, p?<?0.001; IVRT, 81?±?27 vs. 92?±?22 ms, p?=?0.001; E_m, 9?±?4 vs. 10?±?4 cm/s, p?=?0.008; E/E_m ratio, 11?±?5 vs. 8?±?4, p?<?0.001) in comparison to patients with nonfragmented QRS. There was a significant negative correlation between the number of fQRS and left ventricle systolic functions (for LVEF%, r?=???0.595, p?<?0.001). After adjustment for age and gender, the number of fQRS remained significantly negatively associated with left ventricular systolic and diastolic functions.

Conclusion

We found that fQRS is related to left ventricular systolic dysfunction and diastolic dysfunction. fQRS, which may be the result of myocardial ischemia or scar on myocardial electrical parameters at the cellular level, may represent inadequate systolic and diastolic functions.     

Clinical implications of left ventricular assist device implantation in patients with an implantable cardioverter-defibrillator

Purpose

This study aims to study the clinical implications of the concomitant use of a left ventricular assist device (LVAD) and an implantable cardioverter-defibrillator (ICD).

Methods

In this retrospective study, all patients who underwent LVAD (Heart Mate II) implantation with concomitant ICD therapy at our institution between June 2007 and August 2012 were included. We sought to investigate (1) the electromagnetic interference between LVAD and ICD telemetry, (2) the effect of LVAD implantation on right ventricular (RV) lead parameters and (3) the ventricular tachyarrhythmias (VAs) that occur post-LVAD implantation.

Results

Of the 23 patients (53?±?9 years, 73 % male, LVEF 19?±?9 %) included, ICD telemetry was lost in four patients post-LVAD implantation (Saint-Jude-Medical Atlas V-193, V-240, V-243, and Sorin CRT-8750), prompting either use of a metal shield (n?=?1), a change in position of the programmer head (n?=?1) or ICD replacement (n?=?2). LVAD implantation was associated with a decrease in both RV signal amplitude (p?=?0.04) and RV impedance (p?<?0.01), and a trend towards an increased RV pacing threshold (p?=?0.08), without affecting clinical outcome. Eleven patients (47.8 %) experienced VAs after LVAD implantation, which on the whole were well tolerated. Their occurrence was strongly linked to a history of VAs before device implantation (p?<?0.01).

Conclusions

Electromagnetic interference between LVADs and ICD telemetry may necessitate ICD replacement. LVAD placement is associated with significant changes in RV lead parameters that have minimal clinical significance. VAs occur in approximately half of LVAD patients seen and their occurrence is strongly related to a history of VAs prior to LVAD implantation.