Sinus Beats Research Articles

Double rhythm mapping for coherent electrophysiological substrate characterization in atrial fibrillation patients

Abstract Funding Acknowledgements Type of funding sources: None. Background Atrial fibrillation (AF) progresses with a cascade of combined structural, functional, and systemic dysfunctions. Electro-anatomical maps are employed to investigate pro-arrhythmic areas, characterized by abnormal electrical properties. However, single rhythm maps provide only a partial reconstruction: rhythm and wavefront directionality might mask some of these areas. Purpose To demonstrate that the combined quantitative analysis of different rhythm maps (i.e., parallel sinus rhythm and paced maps) could allow consistent identification of structural and functional defects sustaining AF. Methods Thirty AF clinical procedures have been performed with mapping system support. In particular, a sinus rhythm activation map and a paced map have been created with a multipolar catheter exploiting the parallel mapping feature by setting an extra beat (pacing interval = ERP + 40 ms) every three sinus beats. Areas of abnormal conduction have been identified and a comparison of electrophysiological biomarkers (EGMs voltage and fractionation) among the two rhythms has been performed. Results This comparative analysis allowed us to identify both structural and functional electrophysiological phenomena. Specifically, we distinguished: (i) abnormal conduction zones confirmed in both maps, both characterized by signal fractionation and a lower voltage (0,56 ± 0,18 mV) with respect to healthy atrial tissue (2,40 ± 0,41 mV), and (ii) abnormal conduction zones visible in only one of the two maps. In the latter, we distinguished whether the absence of the phenomena was due to wavefront orthogonality to the diseased area (revealed in paced rhythm thanks to a change in wavefront direction) or due to the presence of a functional phenomenon induced by the pacing. In the first group signal fractionation has been detected in both rhythms and a lower voltage has been found (1,79 ± 1,1 mV) with respect to normal conduction zones (3,26 ± 0,98 mV), while in functional cases EGMs fractionation has been identified only in paced maps and no significant difference has been observed in terms of voltage. Conclusion Double rhythm mapping provides a more robust characterization of atrial abnormal conduction phenomena. In fact, it allowed the distinction of true structural dysfunctions from dynamic (functional) ones thanks to the different wavefront directionality and rhythm. Moreover, the structural defects have been confirmed by EGMs analysis, which revealed both low voltage amplitude and high fractionation, characteristics that have not been reported in functional cases.

C4 DOUBLE RHYTHM MAPPING FOR COHERENT ELECTROPHYSIOLOGICAL SUBSTRATE CHARACTERIZATION IN ATRIAL FIBRILLATION PATIENTS

Abstract Background Atrial fibrillation (AF) progresses with a cascade of combined structural, functional, and systemic dysfunctions. Electro–anatomical maps are employed to investigate pro–arrhythmic areas. However, single rhythm maps provide only a partial reconstruction: rhythm and wavefront directionality might mask some of these areas. Purpose. To demonstrate that the combined quantitative analysis of different rhythm maps (i.e., parallel sinus rhythm and paced maps) could allow consistent identification of structural and functional defects sustaining AF. Methods Thirty AF clinical procedures have been performed with mapping system support. In particular, a sinus rhythm activation map and a paced map have been created with a multipolar catheter by setting an extra beat every three sinus beats. Areas of abnormal conduction have been identified and a comparison of electrophysiological biomarkers (EGMs voltage and fractionation) among the two rhythms has been performed. Results This comparative analysis allowed us to identify both structural and functional electrophysiological phenomena. Specifically, we distinguished: (i) abnormal conduction zones confirmed in both maps, both characterized by signal fractionation and a lower voltage (0,56 ± 0,18 mV) with respect to healthy atrial tissue (2,40 ± 0,41 mV), and (ii) abnormal conduction zones visible in only one of the two maps. In the latter, we distinguished whether the absence of the phenomena was due to wavefront orthogonality to the diseased area (revealed thanks to a change in wavefront direction) or due to the presence of a functional phenomenon induced by the pacing. In the first group signal fractionation has been detected in both rhythms and a lower voltage has been found (1,79 ± 1,1 mV) with respect to normal conduction zones (3,26 ± 0,98 mV), while in functional cases EGMs fractionation has been identified only in paced maps and no significant difference has been observed in terms of voltage. Conclusion Double rhythm mapping provides a more robust characterization of atrial abnormal conduction phenomena which better represent AF electrical substrate. It allows the distinction of true structural dysfunctions from dynamic ones thanks to the different wavefront directionality and paced rhythm. Moreover, the structural defects have been confirmed by EGMs analysis, which revealed both low voltage amplitude and high fractionation, characteristics that have not been reported in functional cases.

C72 POSTERIOR WALL CHARACTERIZATION IN PATIENTS AFFECTED BY ATRIAL FIBRILLATION

Abstract Background Several clinical data in humans demonstrate that atrial fibrillation (AF) dominant frequencies and rotors are mostly localized on the posterior wall (PW), but the correlation among these phenomena and abnormal conduction properties during sinus (SR) and paced rhythm (PR) has never been analyzed. Aims. To provide a characterization of the left atrial PW in patients affected by persistent AF. In particular, the purpose is to describe the electrophysiological properties in terms of rotational and focal activities during AF, propagation uniformity during SR and functional sites definition during PR. Methods Six patients from two EP centers have been selected for this analysis. The clinical procedures have been performed with CARTO3 mapping system. All EGMs have been collected with Pentaray and Octaray catheters. For each patient, the module CARTOFINDER has been used during AF to identify areas with shorter and longer cycle length (site of conduction jump), rotational and focal activities; at least 15 areas have been collected in the PW. SR and PR map were performed after electrical cardioversion to exploit the functional phenomena. The paced map has been created by setting an extra beat from the coronary sinus every three sinus beats (pacing interval=local effective refractory period +40ms). Rotational and focal activities during AF have been identified and associated with signals collected during SR and PR. EGMs have been characterized in terms of voltage amplitude (mV), signal duration (ms) and fractionation. Results Abnormal areas of conduction recorded during AF were 33; at least one site of conduction jump was found in every patient, in most of the cases (77%, 10 out of 13) it was localized on the PW. 10 areas of focal activities have been found of which 7 (70%) were localized on the PW. Rotational activity has been found in 2 patients (in one on the PW). During SR and paced rhythm, at sites of interest, we found lower voltages (SR 1.9 ± 1,3mV, PR 1,7 ± 1,15mV), signal fragmentation and longer signal duration (SR 52,7 ± 8,85ms, PR 51,3 ± 11,04ms) compared to healthy tissue. Conclusion There is a strong correlation between sites of interest during AF and signal abnormalities recorded during SR and PR. This research work may pave the way to the study of abnormal conduction sites during SR which represent a relevant element for AF maintenance, providing a further step towards substrate characterization in patients affected by AF.

Prophylactic use of a lidocaine constant rate infusion versus saline in dogs undergoing balloon valvuloplasty for management of pulmonic stenosis: A randomized control trial

ObjectiveTo evaluate the effect of a prophylactic lidocaine constant rate infusion (CRI) on the incidence and malignancy of catheter-induced ventricular ectopic complexes (VECs) during balloon valvuloplasty for management of pulmonic stenosis in dogs. Study designSingle-centre, prospective, randomized study. AnimalsClient-owned dogs (n = 70) with pulmonic stenosis. MethodsDogs were randomly assigned to one of two anaesthetic protocols: administration of lidocaine 2 mg kg–1 bolus followed by a CRI (50 μg kg–1 minute–1; group LD) or a saline placebo (group SL) during balloon valvuloplasty. All dogs were premedicated with methadone (0.3 mg kg–1) intramuscularly and a digital three-lead Holter monitor was applied. Anaesthetic co-induction was performed with administration of alfaxalone (2 mg kg–1) and diazepam (0.4 mg kg–1), and anaesthesia was maintained with isoflurane vaporised in 100% oxygen. CRIs were started on positioning of the dog in theatre and discontinued as the last vascular catheter was removed from the heart. All dogs recovered well and were discharged 24 hours postoperatively. Blinded Holter analysis was performed by an external veterinary cardiologist using commercially available dedicated analysis software; p < 0.05. ResultsOf the 70 dogs enrolled in the study, 61 were included in the final analysis: 31 in group LD and 30 in group SL.There was no significant difference between sinus beats (p = 0.227) or VECs (p = 0.519) between groups. In group LD, 19/31 (61.3%) dogs had a maximum ventricular rate ≥250 units and 20/30 (66.7%) dogs in group SL (p = 0.791). Conclusion and clinical relevanceIn this study, the use of a prophylactic lidocaine bolus followed by CRI in dogs undergoing balloon valvuloplasty for management of pulmonic stenosis did not significantly decrease the incidence nor the malignancy of VECs during right heart catheterization compared with a saline CRI.

Aberrant Ventricular Conduction: Revisiting an Old Concept.

The well-defined concept of aberrant ventricular conduction was introduced over 100 years ago and, despite advances in cardiac physiology and electrophysiologic testing, it is still widely misunderstood. Aberrant ventricular conduction is due to physiologic refractoriness of the His-Purkinje system and in most cases does not reflect underlying conduction system disease. Electrophysiologically, aberrant ventricular conduction can manifest with premature atrial ectopics, the Ashman phenomenon with atrial tachyarrhythmias, concealed conduction, echo beats and with the sinus mechanism including rate dependent bundle branch block, bradycardia dependent bundle branch block and early sinus beats. It is important to recognise aberrant ventricular conduction in the context of a broad complex tachycardia, as the differentiation between supraventricular tachyarrhythmias with aberrant ventricular conduction and ventricular tachyarrhythmias carry different therapeutic and prognostic implications. This review will define the ECG footprints of aberrant ventricular conduction to allow accurate ECG interpretation.

PO-03-088 TWO-DIMENSIONAL SPECKLE TRACKING ECHOCARDIOGRAPHY SHOWS THAT LEFT BUNDLE BRANCH PACING MAINTAINS LEFT VENTRICULAR GLOBAL LONGITUDINAL STRAIN AND CONTRACTILITY COMPARED TO RIGHT VENTRICULAR APICAL PACING

Pacemaker-dependent patients with right ventricular (RV) apical pacing are at increased risk for reduced left ventricular function, ventricular dyssynchrony, and the development of pacing-induced heart failure. Physiological pacing of the conduction system through the left bundle branch (LBB) has been shown to have improved synchrony of the ventricles and a more physiological activation sequence. Direct comparison of left ventricular (LV) strain using LBB and RVAP in paired experiments in the same animals or patients has not been published. Evaluate the changes to the left ventricular mechanics (global longitudinal strain (GLS), global circumferential strain (GCS), global radial strain (GRS), and left ventricular ejection fraction (LVEF) through LBB pacing compared to RV pacing using two-dimensional speckle tracking echocardiography. Under anesthesia, six mixed breed hounds had pacing leads from two ICDs (CobaltTM XT DR, Medtronic, Inc) implanted at the RV apex (6947 Sprint Quattro SecureTM, Medtronic, Inc) and the LBB (3830 SelectSecureTM, Medtronic, Inc). Echocardiographic measurements were taken for sinus rhythm, LBB pacing, and RV pacing to evaluate the LV strain, and contractility. Two-dimensional speckle tracking was performed following the pacing procedure to determine GLS, and LVEF from the four-chamber apical views, GCS, and GRS from the short-axis views. In our study, LV GLS was maintained better during LBB pacing when compared to LV GLS during RV pacing. The magnitude of GLS was not significantly different between sinus and LBB pacing, but was significantly lower for RV pacing than both sinus and LBB pacing (Fig. A). GCS only showed a significant difference between sinus and RV pacing (Fig. B), while GRS did not show differences between any of the groups (Fig. C). Results for the LV ejection fraction followed a similar pattern as the GLS. There was not a significant difference in LVEF for sinus and LBB pacing, but LVEF was significantly lower for RV pacing compared to both sinus and LBB pacing (Fig. D). LBB pacing preserves GLS, and the LVEF better than RV apical pacing and is similar to sinus beats. This further supports LBB pacing as a preferred method of pacing for preserving contractility for patients with pacemakers.

Recognizing Patterns on a Resting 12-Lead Electrocardiogram

Scenario: During an annual physical examination, a healthy 55-year-old man who works as a long-haul truck driver had a routine 12-lead electrocardiogram (ECG) recorded. Overall, he had no complaints and was asymptomatic. His body mass index was within normal limits, and he was taking simvastatin for high cholesterol and lisinopril for high blood pressure (current blood pressure, 128/78 mm Hg).Sinus rhythm at 85 beats per minute with first-degree atrioventricular (AV) block and premature ventricular contractions (PVCs) in a trigeminy pattern.Trigeminy is a pattern of PVCs occurring in a series of 3 heart beats, either 2 normal sinus beats followed by a PVC (as in this example) or 1 normal sinus beat followed by 2 PVCs. Trigeminy is not common, is often transient, and can disturb the normal contraction and cardiac output of the heart because a premature impulse interrupts sinus rhythm. In this case, there are more sinus beats than PVCs, most likely supporting normal cardiac output. The PVCs are similar in morphology, or unifocal, suggesting the origin (focus) is at 1 ventricular site. The etiology of trigeminy is not definitive, but some causes include caffeine, medications (eg, antihistamines), alcohol, anxiety, and heart disease. Of note, the PR interval is slightly prolonged (210 milliseconds), meeting criteria for a first-degree AV block. This occurs when electrical conduction through the AV node is slowed but atrial to ventricular conduction is not interrupted. In this case, the continuous rhythm strip at the bottom of the 12-lead ECG is very helpful in capturing the onset and offset of the PVCs. Also, the low R-wave amplitude may be a sign for hypertensive patients requiring further workup with echocardiography.Although this patient is asymptomatic, options to monitor the patient for a long, continuous period include portable monitors like a Holter or event recorder to improve assessment of the prevalence of the PVCs and other dysrhythmias. Potential modifications that should be recommended to this patient to avoid possible triggers include reducing caffeine intake, managing anxiety, monitoring his blood pressure, and exercising (given the sedentary nature of his profession). In general, first-degree AV block is considered benign, is not traditionally treated, and in this case was not new. However, recent epidemiological research from the Framingham study indicates a relationship between first-degree AV block and a higher risk of hospitalization for heart failure, cardiovascular mortality, and all-cause mortality. Although currently asymptomatic, the patient should monitor for potential symptoms of worsening of cardiovascular health, for example, new-onset palpitations. If symptoms develop and evidence suggests more sustained arrhythmia, an echocardiogram may be warranted.

Intra-Individual Comparison of Sinus and Ectopic Beats Probing the Ventricular Gradient’s Activation Dependence

Wilson assumed that the ventricular gradient (VG) is independent of the ventricular activation order. This paradigm has often been refuted and was never convincingly corroborated. We sought to validate Wilson's concept by intra-individual comparison of the VG of sinus beats and ectopic beats, thus assessing the effects of both altered ventricular conduction (caused by the ectopic focus) and restitution (caused by ectopic prematurity). We studied standard diagnostic ECGs of 118 patients with accidental extrasystoles: normally conducted supraventricular ectopic beats (SN, N = 6) and aberrantly conducted supraventricular ectopic beats (SA, N = 20) or ventricular ectopic beats (V, N = 92). In each patient, we computed the VG vectors of the predominant beat, VGp→, of the ectopic beat, VGe→, and of the VG difference vector, ΔVGep→, and compared their sizes. VGe→ of the SA and V ectopic beats were significantly larger than VGp→ (53.7 ± 25.0 vs. 47.8 ± 24.6 mV∙ms, respectively; p < 0.001). ΔVGep→ were three times larger than the difference of VGe→ and VGp→ (19.94 ± 9.76 vs. 5.94 mV∙ms, respectively), demonstrating differences in the VGp→ and VGe→ spatial directions. The amount of ectopic prematurity was not correlated with ΔVGep→, although the larger VG difference vectors were observed for the more premature (<80%) extrasystoles. Electrical restitution properties and electrotonic interactions likely explain our findings. We conclude that the concept of a conduction-independent VG should be tested at equal heart rates and without including premature extrasystoles.

Individuals with a previous symptomatic COVID-19 infection have altered heart rate and blood pressure variability during acute exercise.

Introduction: As the number of COVID-19 cases begin to diminish it is important to turn our attention to any long-term issues that may be associated with a prior infection. Cardiovascular defects have been noted following prior SARS-CoV-2 infections. However, less is known about how a previous infection alters the cardiovascular response to exercise. Further, differences may exist during exercise between previously SARS-CoV-2 positive individuals who had symptoms (symptomatic) relative to those who did not have symptoms (asymptomatic). We hypothesized that previously symptomatic (S) COVID-19 recoveries have an altered cardiovascular response to acute exercise relative to both control (CON; never infected), and previously COVID-19 positive asymptomatic (AS) individuals. Methods: Twenty-seven subjects (CON = 9; AS = 9; S = 9) underwent 30min of submaximal treadmill exercise. During exercise, blood pressure was recorded on the brachial artery every 5min and 3-lead electrocardiography was measured continuously. Indirect indicators of autonomic nervous system health: heart rate variability and blood pressure variability were measured during each session. Baseline mean arterial pressure (MAP) was taken prior to exercise in seated, standing and supine positions. Results: Blood pressure was similar (p > 0.05) amongst all three groups. There were no differences between average heart rate (HR; CON = 104 ± 4 BPM vs AS = 118 ± 6 BPM vs. S = 112 ± 3 BPM), mean arterial pressure (MAP; CON = 108 ± 4mmHg vs. AS = 105 ± 13mmHg vs. S = 108 ± 7mmHg) or oxygen consumption (VO2) between groups during a bout of exercise. However, the standard deviation of the inter beat intervals of normal sinus beats, a measure of heart rate variability (HRV) (CON = 138 ± 2.8m vs. AS = 156 ± 6m vs. S = 77.7 ± 11m; p < 0.05) and blood pressure variability (BPV; CON = 5.18 ± 1.1 vs. AS = 12.1 ± 0.88mmHg vs. S = 10.2 ± 10.7mmHg; p < 0.05) were different in our S group. Further, when HRV was assessed in the frequency domain the very low frequency was different during exercise in the S group relative to the other groups. Discussion: Collectively, these data suggest that a previous symptomatic SARS-CoV-2 infection may alter heart rate and blood pressure regulation during exercise.

Syncope After Transcatheter Aortic Valve Implantation: Pace or Not?

Syncope After Transcatheter Aortic Valve Implantation: Pace or Not?

Ventricular Tachycardia Storm Management in Acute Cardiac Care: Prompt response to life-threatening conditions

Background: Ventricular Tachycardia (VT) storm or electrical storm (ES) is defined as cardiac electrical instability and refers to the occurrence of three or more ventricular tachyarrhythmias (VT and or ventricular fibrillation (VF)) in a 24-hour period, or VT recurring soon (within five minutes) after termination of another VT episode, or sustained or no sustained VT with total ectopic beats greater than sinus beats in a 24-hour period. The frequency of VT storms varies on population. When ICDs are implanted for primary prevention (4 percent), it is lower than when they are implanted for secondary prevention (20 percent). Case Summary: We presented patient with Ventricular Tachycardia (VT) storm. A 63-year old woman was admitted to emergency room with chief complaint frequent episodes of palpitation. She was found to have monomorphic VT with unstable hemodynamic. Then she got cardioversion 100 Joule, continued with lidocaine drip and VT reverted to sinus rhythm. Patient admitted to cardiovascular care unit, but she had VT refractory. She got complete revascularization for coronary artery before, but the episodic of VT still occurred with cardiogenic shock (CS) and pulmonary edema. She got cardioversion, amiodarone iv and inotropes, then observed this patient at CVCU. After the condition stable, this patient was discharged and planned for ICD insertion at the next admission. Discussion: We discuss the various available treatment options for VT storm and practical challenges faced in management of hemodynamically unstable VT storm. Initial management involves identifying and correcting the underlying ischemia, electrolyte imbalances, or other inciting factors.

Analysis of Heart Rate Variability in Obstructive Sleep Apnea Hypoventilation Syndrome

A total of 110 patients with obstructive sleep apnea hypoventilation syndrome were selected from January 2017 to December 2018, including 76 cases of men and 34 females, aged 40-50 y and according to the apnea hyponea index, patients were classified into 3 groups of moderate to moderate and 5 apnea hyponea index 20 was divided into group A (36 cases), the 40 of 20 to apnea hyponea index is divided into group B (45 cases) and apnea hyponea index the 40 of 20 to 40 is divided into group B (45 cases) and apnea hyponea index to 40 is divided into group C (29 cases). In the same period in the health check-up center to extract 40 cases without obstructive sleep apnea hypopnea syndrome, arrhythmia and other medical history of health check-up objects. 24 h Holter-monitoring and polysomography monitoring of 4 groups of people, observed and recorded heart rate variability indicators for each group, including all standard deviations for sinus cardiac arrest, standard deviation per 5 min sinus cardiac interstitial period, the average root mean square of successive differences of the total sinus intercardial period difference is divided by the number of individuals of the sinus cardiac interstitial period of 50 ms the average root mean square of successive differences of the total sinus intercardial period difference is divided by the number of individuals of the sinus cardiac inner struggle period of 50 ms divided by the percentage of the total sinus cardiac inner struggle period (proportion of NN50), low frequency and high frequency. Standard deviation of all sinus beats, standard deviation of the mean value of sinus, root mean square of successive differences, proportion of NN50, low frequency and high frequency were lower than those in the control group (p<0.05) in patients with obstructive sleep apnea hypopnea syndrome. The proportion of NN50 and high frequency in group C were lower than A and B (p<0.05) and the low frequency was higher than the proportion of NN50 and high frequency in group C were lower than A and B (p<0.05) and the low frequency was higher than group A, group B and control group (p<0.05). Holter-monitoring is a non-invasive test, the price is not high and it can be a regular test for testing the autonomic nervous function in patients with obstructive sleep apnea hypopnea syndrome.

A clue to the triples from an echo.

A clue to the triples from an echo.

자율신경검사의 해석과 임상적용

Autonomic nervous system (ANS) consists of sympathetic and parasympathetic components. ANS has a role in heart function and contraction and relaxation of smooth muscle in various internal organs. Several tests were introduced to assess ANS function. Heart rate variability (HRV) is the most common method to evaluate ANS function. HRV is defined as a physiologic variation between sinus beats, which is calculated into standard deviation of N-N interval. The indices derived from beat-to-beat variation are calculated based on time-domain analysis. Fourier transformation visualizes frequency-based graphs from the time-domain tachograms. Areas in the low frequency represent sympathetic predominant function, while high frequency areas show parasympathetic tone. Despite absence of the reference ranges of the HRV indices, studies have shown the ranges of the indices in their populations. Decrease in HRV may be a poor prognostic factor for heart disease, infection, and neuropsychiatric disorders. It is reported that HRV biofeedback improved various disorders related to ANS function. In addition, the results of HRV tests may guide functional approaches. In conclusion, the awareness on ANS function and HRV may help to provide patients with risk stratification and proper management.

RF02 | PMON308 Hyperglycemia Is the Main Determinant of Cardiac Autonomic Dysfunction in Youth With Obesity Across the Spectrum of Glycemic Regulation.

Abstract Heart Rate Variability (HRV) results from the autonomic nervous system activity, it is a non-invasive marker of cardiac autonomic function. Loss of parasympathetic function (PNS) and sympathetic (SNS) override, reflected in decreased HRV, is one of the earliest subclinical manifestations of cardiac autonomic dysfunction. Lower HRV is associated with increased risk of cardiac events in adults. We aimed to characterize HRV in normal weight and overweight children with and without dysglycemia and to investigate the determinants of HRV in these youth, including body composition, glycemia measures, beta-cell function and inflammatory markers. We evaluated 94 adolescents (50 males/44 females), age 15 ± 2.1 years; 21 normal weight with normal glucose tolerance (NW-NGT), 23 overweight with NGT (OW-NGT) and 50 overweight with impaired glucose regulation (OW-IGR) including prediabetes (n= 27) and type 2 diabetes (n= 23). They underwent assessment of anthropometrics, body composition (DXA scan), inflammatory markers (hs-CRP and TNF-α), fasting labs and 2-hour oral glucose tolerance test (OGTT) with determination of glucose and insulin concentration. EndoPat was used to measure HRV: frequency-domain indices [high-frequency (HF) reflecting PNS, low-frequency (LF) reflecting both PNS and SNS, and LF/HF (higher is worse) estimating the ratio between SNS and PNS] and time-domain indices [the inter-beat interval of normal sinus beats (NN) and the standard deviation of NN (SDNN) measuring overall HRV, the square root of the mean squared difference of successive NN (RMSSD) and the NN intervals differing by more than 50 milliseconds (NN50) measuring PNS activity]. LF/HF was higher in the OW-IGR group compared with NW and OW-NGT (p=0.005). After controlling for sex, race and Tanner stage, fasting glucose (FBG) negatively correlated with NN (r=-0.22,p=0.04), SDNN (r=-0.21,p=0.05), RMSSD (r=-0.3,p=0.004), NN50 (r=-0.27,p=0.01) and HF (r=-0.26,p=0.02). LF/HF was positively related to FBG (r=0.39,p&amp;lt;0.001), 2hr-glucose (r=0.31,p=0.004) and HbA1c (r=0.22,p=0.04), and negatively with the insulinogenic index (r=-0.27,p=0.02), but not fasting insulin or HOMA-IR; LF/HF also correlated with percent body fat (r=0.22,p=0.04), hs-CRP (r=0.33,p=0.002) and TNF-α (r=0.38,p=0.006). In a linear regression model with LnLF/HF as the dependent variable and percent body fat, hs-CRP, FBG and HOMA-IR as the independent variables, FBG (beta=0.39,p=0.003) and hs-CRP (beta=0.21,p=0.09) were the significant determinants of LnLF/HF independent of age, sex, race and Tanner stage as covariates (R2= 0.23,p=0.013). Youth with impaired glucose metabolism have evidence of early subclinical cardiac autonomic dysfunction with decreased HRV, loss of parasympathetic function and sympathetic overdrive as reflected by lower time-domain indices, lower HF and higher LF/HF, related to glycemia and systemic inflammation. Presentation: Saturday, June 11, 2022 1:00 p.m. - 2:00 p.m., Saturday, June 11, 2022 1:12 p.m. - 1:17 p.m., Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

The R-S difference index: A new electrocardiographic method for differentiating idiopathic premature ventricular contractions originating from the left and right ventricular outflow tracts presenting a left bundle branch block pattern.

Introduction: Differentiating idiopathic premature ventricular contractions (PVCs) originating from the right and left ventricular outflow tracts with a left bundle branch block (LBBB) morphology is relevant to catheter ablation planning and important for lowering the risk of complications. This study established a novel electrocardiographic (ECG) criterion to discriminate PVCs originating from the septum of the right ventricular outflow tract (s-RVOT) and those originating from the aortic sinus cusp of the left ventricular outflow tract (LVOT-ASC). Methods: A total of 259 patients with idiopathic PVCs originating from ventricular outflow tract with a LBBB pattern who underwent successful catheter ablation were retrospectively included. Among them, the PVCs originated from the s-RVOT in 183 patients and from the LVOT-ASC in 76 patients. The surface ECGs of the PVCs and sinus beats were analyzed using an electronic caliper. The R-S difference index in the precordial leads was calculated as V2R + V3R + V4R − V1S. Results: PVCs originating from both the s-RVOT and LVOT-ASC displayed an inferior axis (dominant R waves in leads II, III, and aVF). Compared with the s-RVOT group, the R-wave amplitudes on leads II, III, and aVF were significantly larger in the LVOT-ASC group (p < 0.001, p < 0.003, and p < 0.001, respectively). Compared to the LVOT-ASC group, the s-RVOT group showed smaller R-wave amplitudes on leads V1–V6 (p = 0.021, p < 0.001, p < 0.001, p < 0.001, p < 0.001, and p < 0.001, respectively) and larger S-wave amplitudes on leads V1–V3 (p < 0.001, p < 0.001, and p < 0.001, respectively). Lead V3 was the most common transitional lead in both groups. Analysis of the receiver operating characteristic curve showed that the R-wave amplitude on lead V3 had the largest area under the curve (AUC) of 0.856 followed by the R-wave amplitudes on leads V4 (0.834) and V2 (0.806). The AUC of the R-S difference index was 0.867. An R-S difference index greater than 20.9 predicted an LVOT-ASC origin with 73.7% sensitivity and 86.3% specificity. This index is superior to previous criteria in differentiating PVCs with LBBB morphology and inferior axis originating from s-RVOT vs. LVOT-ASC. Conclusions: The R-S difference index in precordial leads is a useful new ECG criterion for distinguishing LVOT-PVCs from RVOT-PVCs with LBBB morphology.

Premature Ventricular Contractions Are Presaged by a Mechanically Abnormal Sinus Beat.

Frequent premature ventricular contractions (PVCs) can lead to cardiomyopathy; it is unclear if there are abnormal myocardial mechanics operative in the PVC and non-PVC beats. The aim of this study was to investigate regional and global myocardial mechanics, including dyssynchrony, in patients with frequent PVCs. Fifty-six consecutive patients referred for PVC ablation were prospectively studied. During sinus rhythm (SR) and PVC beats, left ventricular (LV) global longitudinal strain (GLS), LV dyssynchrony (measured as the SD of time to peak GLS), and dyssynergy (measured as maximum regional strain minus minimum regional strain at aortic valve closure) were quantified using 2-dimensional strain echocardiography. GLS, dyssynchrony, and dyssynergy were compared in remote SR, pre-PVC SR, PVC, and post-PVC SR beats. In SR beats remote from the PVC, GLS was-17.3% ± 4%, dyssynchrony was 49 ± 14ms, and dyssynergy was22% ± 9%. Myocardial mechanics were significantly abnormal during PVCs compared with remote SR beats (GLS-7.7% ± 3% [P< 0.001], dyssynchrony 115 ± 37 milliseconds [P< 0.001], and dyssynergy 26% ± 10% [P<0.001]). There were significant mechanical abnormalities in the SR beat preceding the PVC, which demonstrated significantly lower LV strain (pre-PVC SR,-13% ± 4%; P< 0.001) and more dyssynchrony (pre-PVC SR, 63 ± 19 milliseconds; P< 0.001) compared with remote SR beats. Dyssynergy was significantly higher for pre-PVC SR and PVC beats compared with remote SR (pre-PVC SR, 25% ± 8% [P< 0.001]; PVC, 26% ± 10% [P< 0.001]). In patients with frequent PVCs, the SR beat preceding the PVC demonstrates significant mechanical abnormalities. This finding suggests that perturbations in cellular physiological processes such as excitation-contraction coupling may underlie the generation of frequent PVCs.

Spatial correction improves accuracy of catheter positioning during ablation of premature ventricular contractions: differences between ventricular outflow tracts and other localizations

BackgroundHybrid activation mapping is a novel tool to correct for spatial displacement of the mapping catheter due to asymmetrical contraction of myocardium during premature ventricular contractions (PVC). The aim of this study is to describe and improve our understanding of spatial displacement during PVC mapping as well as options for correction using hybrid activation mapping.Methods and resultsWe analyzed 5798 hybrid mapping points in 40 acquired hybrid maps of 22 consecutive patients (age 63 ± 16 years, 45% female) treated for premature ventricular contractions (PVCs). Median PVC-coupling interval was 552 ms (IQR 83 ms). Spatial displacement was determined by measuring the dislocation of the catheter tip during PVC compared to the preceding sinus beat. Mean spatial displacement was 3.8 ± 1.5 mm for all maps. The displacement was 1.3 ± 0.4 mm larger for PVCs with non-outflow-tract origin compared to PVCs originating from the ventricular outflow tracts (RVOT/LVOT; p = 0.045). Demographic parameters, PVC-coupling-interval and chamber of origin had no significant influence on the extent of spatial displacement.ConclusionEctopic activation of the ventricular myocardium during PVCs results in spatial displacement of mapping points that is significantly larger for PVCs with non-outflow-tract origin. The correction for spatial displacement may improve accuracy of radiofrequency current (RFC)-application in catheter ablation of PVCs.

What Is the Mechanism of This Cardiac Rhythm?

An 80-year-old man with syncope was admitted for evaluation. His clinical examination revealed nothing remarkable. He had no history of heart disease, his blood pressure and electrolyte levels were normal, and he was taking no medications known to cause bradyarrhythmia. Overnight telemetry revealed the electrocardiogram displayed below (Fig. 1).The rhythm strip suggests which diagnosis?D) Junctional escape and intermittent capture beatsThe telemetry strip displayed junctional rhythm, sinus capture after every second junctional rhythm, and right bundle branch block (RBBB) of the sinus-captured beat (Fig. 2). This rare phenomenon, wherein a sinus-captured beat occurs after 2 junctional escape beats, is termed escape-reentry-capture trigeminy.1In isorhythmic atrioventricular (AV) dissociation (Answer A), the atria and ventricles beat at the same rate but are dissociated from each other; here, however, the junctional beat with retrograde conduction to the atria rules out dissociation between competing rhythms. The lack of clear P waves preceding the QRS complexes and the absence of progressive PR prolongation makes Mobitz type I AV block (Answer B) unlikely. Premature ventricular contractions in trigeminy (Answer C) are unlikely because the wide complexes with RBBB morphology are preceded by a P wave, and the QRS pattern simulates a “typical” RBBB. The 2 junctional beats followed by P-wave capture makes premature atrial complexes in trigeminy (Answer E) unlikely.Escape-reentry-capture occurs in the presence of sinus nodal dysfunction (sick sinus syndrome) when the sinus impulse rate is slower than the junctional escape rate. The inverted P wave in Figure 2 (arrows) suggests that the first junctional beat was conducted retrograde to the atria, that the next junctional beat was not, and that the subsequent sinus beat was conducted with an RBBB. This aberrancy may be explained by the “long-short” sequence that prolongs the effective refractory period of the right bundle. Consequently, the sinus rate was apparently slow enough to be captured in a trigeminal pattern. Note also that the junctional rhythm did not affect the sinus rate. The patient was given a permanent pacemaker. This case illustrates the escape-reentry-capture phenomenon in a trigeminal pattern caused by sinus nodal dysfunction.Conflict of Interest Disclosure: NoneFunding/Support: None

Premature Complexes and Blocked P Wave.

Premature Complexes and Blocked P Wave.