Normal Heart Group Research Articles

Eligibility for subcutaneous implantable cardiac defibrillator utilising artificial intelligence and deep learning methods for prolonged screening: where is the cut-off?

Abstract Funding Acknowledgements Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Main author is receiving an unrestricted grant by Boston Scientific Background S-ICD eligibility is determined by a single surface ECG analysis in which the suitability of an individual’s ECG vector morphology is assessed. A major predictor of eligibility is the T:R ratio. Current screening tools proposes T: R of 1:3 as a cut-off for eligibility. Inappropriate shocks due to T-wave oversensing (TWO) remains an issue despite screening. EFFORTLESS and PRAETORIAN trials reported inappropriate shock rates of 11.4% and 9.7% respectively, most frequently caused by cardiac oversensing. Purpose The cut-off T: R of 1:3 currently used incorporates a safety margin to accommodate for ECG signal amplitudes fluctuations without affecting S-ICD sensing. Prolonged screening using our tool accurately measures the T: R fluctuations. However, utilising a T: R of 1:3 for prolonged screening can unnecessarily exclude appropriate S-ICD candidates. The purpose of our study is to provide groundwork for future trials to find the optimal ratio that identifies patients at risk of TWO and inappropriate shocks while not excluding true S-ICD candidates after prolonged screening. Methods Patients were fitted with 24-hour Holter monitors with leads placed to correspond to the vectors of an S-ICD. We used our tool to assess T: R over the recordings utilising Phase Space Reconstruction matrices - to convert the ECG signal into compressed pixel images. A Convolutional Neural Network (CNN) model was trained to accurately predict the T: R from these images resulting in a T: R variation plot for each vector. We then applied multiple T:R ratio cut-offs on the recordings to identify patients at risk of inappropriate shocks due to TWO at each proposed value. A vector with a T: R above the cut-off for 20 consecutive seconds was deemed to have failed screening, the time determined by the current detection, charge, and redetection time of the current S-ICD system. A patient has to have at least one suitable vector to pass the screening at the selected threshold. Results 37 patients (mean age 54.5 years,64.8% male) were included. 14 had Heart failure, 7 Hypertrophic cardiomyopathy, 7 normal hearts, 6 Adult congenital heart disease and 3 patients who received inappropriate S-ICD shocks due to TWO. Overall, 20 (54%) of patients passed prolonged screening using a 1:3 ratio. All of the patients passed screening with a T: R of 1:1. The only subgroup to wholly pass the screening for all the proposed ratios are the normal hearts group. Conclusion We propose adopting prolonged screening to select S-ICD eligible patients with low probability of TWO and inappropriate shocks. However, utilising T: R of 1:3 can unnecessarily exclude otherwise S-ICD eligible patients. The appropriate ratio likely lies between 1:3 - 1:1. Further studies are needed to identify the optimal screening thresholds, particularly in patients that have had inappropriate shocks due to TWO.

A rapid and Easy Objective Evaluation of the Three Vessel View to Enhance Diagnostic Confidence in Fetal Echocardiography

AbstractThe three vessel view (3VV) is an integral component of fetal cardiac screening. The evaluation of vessel size is subjective in this view. Not infrequently, however, there can be a doubt and a need arises for objective assessment. Our aim was to clarify which ratio (AO/PA, AO/SVC, PA/SVC) can most easily judge the 3VV. We measured the diameter of the aorta (AO), pulmonary artery (PA) and superior vena cava (SVC) in 85 fetuses that had been diagnosed with a normal heart (NH) by the spatiotemporal image correlation (STIC) method and calculated the AO/PA ratio, AO/SVC ratio and PA/SVC ratio. We then calculated a similar index using an offline videotape in 15 fetuses diagnosed with coarctation of the aorta (COA), and 15 fetuses diagnosed with Tetralogy of Fallot (TOF). TOF excluded pulmonary atresia and absent pulmonary valve. All of the AO/PA ratios, AO/SVC ratios and PA/SVC ratios recognized a significant difference in the CoA, TOF and the NH groups. When we calculated the ROC curve in each CoA group and TOF group about AO/PA ratio, AO/SVC ratio, PA/SVC ratio, AO/PA ratio showed the highest sensitivity and specificity in the CoA group and the TOF group. When the cut-off value of the CoA for the NH group is AO/PA ratio < 0.7, good results are obtained, sensitivity is 100% and specificity is 90.6%. When the cut-off value of the TOF from the NH group is AO/PA ratio > 1.2, good results are obtained, sensitivity is 100% and specificity is 98.8%. The method to measure AO/PA ratio during heart screening can judge the 3VV objectively. When it exceeds 0.7 < AO/PA ratio < 1.2, it is likely to be congenital heart disease.

Getting to zero: impact of electroanatomical mapping on fluoroscopy use in pediatric catheter ablation.

Over the past several years, alternative imaging techniques including electroanatomic mapping systems such as CARTO®3 (C3) have been developed to improve anatomic resolution and potentially limit radiation exposure in electrophysiology (EP) procedures. We retrospectively examined the effect of the introduction of C3 on patient radiation exposure during EP studies and ablation procedures at a children's hospital. All patients that underwent EP and ablation procedures between January 2012 and August 2015 were included; demographic information, fluoroscopy time (FT), total radiation dose (RAD), and dose-area product (DAP) were collected. Patients were stratified by time period (before vs. after C3 introduction) in three groups: (1) normal heart, (2) congenital heart disease (CHD), and (3) those requiring trans-septal (TS) access. The normal heart group was further separated by arrhythmia diagnosis (accessory pathway (AP), AV nodal reentry tachycardia (AVNRT), atrial, or ventricular arrhythmia). Mean values were compared using a single sample t test, as well as analysis of covariance to control for age, weight, and arrhythmia diagnosis. Mean FT decreased after introduction of C3 in patients in all three patient groups (p < 0.01). When separated by arrhythmia diagnosis, FT decreased in the AP and AVNRT groups (p < 0.0001). After controlling for age, weight, and arrhythmia diagnosis, there was a statistically significant decrease in FT in all three groups and in both RAD and DAP in the normal heart group. Zero fluoroscopy was achieved in 50/159 (31%) and ≤1min of FT in 71/159 (45%) of cases. We have shown a significant decrease in multiple measures of radiation after introduction of C3. Continued refinements are needed to further decrease radiation utilization and achieve the goal of zero fluoroscopy.

3D-Transesophageal Echocardiography in Paradoxical Low-Flow, Low-Gradient Aortic Stenosis

Background: In paradoxical low-flow, low gradient (PLFLG) aortic stenosis, 2D-transthoracic echocardiography (2D-TTE)may underestimate flow because it assumes a circular left ventricular outflow tract (LVOT) shape. Three-dimensional transesophagealechocardiography (3D-TEE) is a better method to measure LVOT area.Objectives: The aim of this study was to evaluate left ventricular stroke volume index (SVi) by 2D-TTE and 3D-TEE in patientswith normal heart (NH) and with severe aortic stenosis (SAS) and to determine how many patients are categorized asPLFLG by 2D-TTE and 3D-TEE.Methods: Thirty-five patients were evaluated by 2D-TEE and 3D-TEE: NH=17 patients and SAS=18 patients. Left ventricularoutflow tract area was estimated during early systole by 2D-TTE (ES2DLVOT Ar) and by 3D-TEE (ES3DLVOT Ar)planimetry, and as systolic average (Avg 3DLVOT Ar). Each LVOT area was multiplied by its corresponding flow integral toobtain SVi (ES2D-TTE SVi, ES3D-TEE SVi and Avg 3D-TEE SVi) in NH and SAS groups. Paradoxical LFLG was determinedin SAS following standard criterion.Results: NH: ES2DLVOT Ar vs. ES3DLVOT Ar p<0.05; SAS: ES2DLVOT Ar vs. ES3DLVOT Ar p<0.001 and vs. Avg 3DLVOTAr p<0.023; ES2D-TTE SVi vs. ES3D-TEE SVi p<0.002 and vs. Avg 3D-TEE SVi p<0.038. In the NH group, the lower limitof normal SVi for 2D-TTE, ES3D-TEE and Avg 3D-TEE was <34, <38.9 and <35.9 ml/m2, respectively. Three SAS patientswere categorized as PLFLG by 2D-TTE, but none by 3D-TEE.Conclusions: Patients with PLFLG by 2D-TTE could

Prevalence of Persistent Superior Vena Cava and Association With Congenital Heart Anomalies

A contralateral persistent superior vena cava (PSVC) can occur in a normal child or in association with congenital heart defects (CHDs). Its prevalence has been demonstrated in relatively small cohorts. We aim to assess the frequency of a PSVC in a large cohort of children with and without CHDs. To estimate its significance, we have searched for a PSVC in all children referred for echocardiography in our institution during a 16.5-year period. Agroup of 17,219 children comprised 8,140 children with a structural heart anomaly and 9,079 children with a structurally normal heart. Association between a PSVC and specific classes of CHD were looked for. A total of 288 children (1.7%) had a PSVC; 0.56% (51 of 9,079) in the normal heart group and 2.9% (237 of 8,140) in the congenital heart anomalies group. Odds ratio for having heart anomaly in the presence of PSVC was 5.2 (95% confidence interval 3.7 to 7.0). A PSVC was above all associated with atrioventricular septal defects, conotruncal malformations, and left-sided defects. The odds ratio of having PSVC in the aforementioned malformations compared with the normal heart group was 23.8, 13.6, and 11.0, respectively. In conclusion, although present in normal subjects, PSVC was more often associated with congenital heart and other anomalies, especially with atrioventricular septal defects, conotruncal malformations, and left-sided defects.

Effects of low-intensity atrial ganglionated plexi stimulation on ventricular electrophysiology and arrhythmogenesis

Atrial ganglionated plexi (GP) have been shown to modulate sinus rate, atrioventricular conduction and atrial electrophysiology. The aim of this study was to investigate the effect of low-intensity GP stimulation (GPS) on ventricular electrophysiological properties in normal heart and on ventricular arrhythmogenesis after acute myocardial ischemia (AMI) in canine. Thirty-nine dogs were assigned into the normal heart group (n=12) and the acute myocardial ischemia (AMI) group (n=27, 12 in control and 15 in low-intensity GPS). In the normal heart group, ventricular effective refractory period (ERP), dynamic restitution and electrical alternans were measured at baseline and after 6-hour low-intensity GPS. In the AMI group, the incidence of ventricular arrhythmias was determined during 1-hour recording after AMI was induced. In the normal heart, 6-hour low-intensity GPS significantly prolonged ventricular ERP and action potential duration (APD) at each site (all P<0.05) but did not change their spatial dispersions when compared with baseline. Low-intensity GPS also caused an upward shift of ventricular restitution curves in each site but did not change the slope of restitution curves. APD alternans after low-intensity GPS occurred at longer pacing cycle length at each site when compared with baseline (all P<0.05). In the AMI heart, the incidence of ventricular arrhythmias in low-intensity GPS group was significantly lower than that in control group (P<0.05). Low-intensity GPS induces no increase in the risk of ventricular arrhythmias in the normal heart as well as protects against ventricular arrhythmogenesis during AMI.

New Unipolar Electrogram Criteria to Identify Irreversibility of Nonischemic Left Ventricular Cardiomyopathy

This study sought to assess the value of left ventricular (LV) endocardial unipolar electroanatomical mapping (EAM) in identifying irreversibility of LV systolic dysfunction in patients with left ventricular nonischemic cardiomyopathy (LVCM). Identifying irreversibility of LVCM would be helpful but cannot be reliably accomplished by bipolar EAM or cardiac magnetic resonance identification of macroscopic scar. Detailed endocardial LV EAM was performed in 3 groups: 1) 24 patients with irreversible LVCM (I-LVCM) but with no or minimal macroscopic scar (<15% LV surface) evidenced on bipolar voltage EAM and/or cardiac magnetic resonance; 2) 14 patients with reversible ventricular premature depolarization-mediated LVCM (R-LVCM); and 3) 17 patients with structurally normal hearts. LV endocardial unipolar electrogram amplitude and area of unipolar amplitude abnormality were defined after excluding macroscopic scar. Unipolar amplitude differed in the 3 groups: median of 7.6 (interquartile range [IQR]: 5.5 to 9.7) mV in I-LVCM group, 13.2 (IQR: 10.4 to 16.2) mV in R-LVCM group, and 16.3 (IQR: 13.6 to 19.8) mV in structurally normal hearts group (p < 0.001). Areas of unipolar abnormality represented a large proportion of total LV surface in I-LVCM, 64.7% (IQR: 47.5% to 75.9%) compared with R-LVCM, 5.2% (IQR: 0.0% to 19.1%) and structurally normal hearts, 0.1% (IQR: 0.0% to 0.9%), groups (p < 0.001). A unipolar abnormality area cutoff of 32% of total LV surface was 96% sensitive and 100% specific in identifying irreversible cardiomyopathy among patients with LV dysfunction (I-LVCM and R-LVCM), p < 0.001. Detailed unipolar voltage mapping can identify irreversible myocardial dysfunction consistent with fibrosis, even in the absence of bipolar EAM or cardiac magnetic resonance abnormalities, and may serve as valuable prognostic tool in patients presenting with LVCM to facilitate clinical decision making.

Effects of ganglionated plexi ablation on ventricular electrophysiological properties in normal hearts and after acute myocardial ischemia

BackgroundGanglionated plexi (GP) ablation has been shown to play an important role in atrial fibrillation (AF) initiation and maintenance. Also, GP ablation increases chances for prevention of AF recurrence. This study investigated the effects of GP ablation on ventricular electrophysiological properties in normal dog hearts and after acute myocardial ischemia (AMI). MethodsFifty anesthetized dogs were assigned into normal heart group (n=16) and AMI heart group (n=34). Ventricular dynamic restitution, effective refractory period (ERP), electrical alternans and ventricular fibrillation threshold (VFT) were measured before and after GP ablation in the normal heart group. In the AMI heart group, the incidence of ventricular arrhythmias and VFT were determined. ResultsIn the normal heart group, GP ablation significantly prolonged ERP, facilitated electrical alternans but did not increase ERP dispersion, the slope of restitution curves and its spatial dispersion. Also, GP ablation did not cause significant change of VFT. In the AMI heart group, the incidence of ventricular arrhythmias after GP ablation was significantly higher than that in the control group or the GP plus stellate ganglion (SG) ablation group (P<0.05). Spontaneous VF occurred in 8/12, 1/10 and 2/12 dogs in the GP ablation group, the GP plus SG ablation group and the control group, respectively (P<0.05). VFT in the GP ablation group showed a decreased trend though a significant difference was not achieved compared with the control or the GP plus SG ablation group. ConclusionsGP ablation increases the risk of ventricular arrhythmias in the AMI heart compared to the normal heart.

Reduction of tricuspid annular doppler tissue velocities in pediatric heart transplant patients

Background: Orthotopic heart transplantation is a life-saving therapy for children with end-stage heart disease. However, 50% of these transplanted children die or require re-transplantation 12 years later. Progressive deterioration of cardiac function is a common feature of long-term survivors; however, quantitative evaluation of the state of the right ventricle has been lacking. Tissue Doppler imaging (TDI) has been used to measure alterations in right ventricular (RV) function in other illnesses. The purpose of this study was to quantitate abnormalities in tricuspid annular systolic and diastolic velocities as an indicator of RV dysfunction, and to evaluate if time since transplantation and the presence of tricuspid regurgitation are associated with quantitative changes in tricuspid annular velocities in pediatric heart transplant recipients. Methods: TDI was performed and velocities recorded during systole and early and late diastole at the tricuspid annulus, septum and mitral annulus in transplanted patients and in a control group with normal hearts. Pulsed wave Doppler mitral and tricuspid inflows were also measured and the severity of tricuspid regurgitation was estimated using color flow mapping. Patients with biopsy evidence of active cellular rejection or left ventricular ejection fraction of <60% were excluded from study. Results: Thirty-five patients were divided into a normal heart group ( n = 14) and a transplant group ( n = 21), aged from 1 to 23 years. Systolic and early diastolic velocities at the tricuspid annulus and septum in the transplant group were reduced significantly compared with the normal group ( p < 0.05): tricuspid annular systolic, 5.8 ± 1.4 vs 9.4 ± 1.7 cm/sec; early diastolic, −6.4 ± 2.6 vs −9.7 ± 2.6 cm/sec; septum systolic, 3.9 ± 1.5 vs 5.8 ± 1.4 cm/sec; and early diastolic, −6.3 ± 2.4 vs −9.1 ± 2.5 cm/sec. Patients were divided into early (<5 years) and late (>5 years) term groups since transplantation. Tissue velocities at the tricuspid annulus in the late term group had further reduction in systole, 4.9 ± 1.4 vs 6.4 ± 1.1 cm/sec, and early diastole, −5.3 ± 1.5 vs −7.1 ± 2.9 cm/sec ( p < 0.05). Patients with severe tricuspid regurgitation had systolic and early diastolic velocities at the tricuspid annulus that were further reduced. Left ventricular mitral inflow Doppler early/late diastolic ratios became significantly different from the normal group 5 years after transplantation ( p < 0.05). Conclusions: TDI demonstrated that tricuspid annular systolic and early diastolic velocities were abnormal in children after transplantation and became significantly more abnormal with prolonged time after transplantation. These alterations were not dependent on the presence of severe tricuspid regurgitation but appeared to be exacerbated by its presence. Evidence of diastolic left ventricular dysfunction was not detected before 5 years after transplantation in this unselected group. A prospective study may be required to define the evolution and progression of right and left ventricular dysfunction in children after heart transplantation.

745-4 Sudden “Arrhythmic” Death in Young People with Apparently Normal Heart

The aim of the present study was to assess whether and how often the ultimate diagnosis of structural heart disease underlying sudden cardiac arrest depends on histologic examination of the myocardium and specialized conduction system. Among 186 cases of consecutive sudden cardiovascular death in young people (≤ 35 yrs) studied from 1979 to 1994, in 59 (32%) gross examination failed to show any cardiac cause of sudden death such as obstructive coronary atherosclerosis, congenital coronary anomaly, cardiomyopathy, valve disease and aortic dissection. The grossly normal heart group consisted of 40 males and 19 females, aged 4–35 yrs (mean 23.7); 27 patients experienced warning symptoms and signs consisting of syncope in 12, ECG abnormalities in 16, and arrhythmias in 11. None had been diagnosed while alive. Detailed histologic study, including examination of ordinary ventricular myocardium as well as serial sections of specialized conduction system, disclosed: 1)focal myocarditis in 17 patients; 2) conduction system abnormalities leading to heart block in 6 patients (sick sinus syndrome in 1, lipomatous discontinuity between the atrial myocardium and the atrioventricular node in 2, sclerotic interruption of His and bundle branches in 2, and longitudinal dissociation of the His bundle in 1). and to ventricular pre-excitation in 15 (atrioventricular by-pass fibers in 9, nodoventricular Mahaim fibers in 4, atriofascicular tract in 1, AV nodal hypoplasia in 1); 3) focal fibrousfatty replacement of the right anterior wall and infundibulum in 5 patients. Sudden death remained unexplained in 16 cases. In conclusion, gross heart features were normal in nearly one third of the young sudden cardiovascular death victims; in 73% of them, however, there was histopathologic evidence of concealed “arrhythmogenic” substrates mostly consisting of conduction system pathology and focal myocarditis.