The comparative relationships between locations of the papillary muscles and electrophysiologic QRS axis in patients with atrioventricular septal defect and common as opposed to separate orifices in the valve guarding the common atrioventricular junction.

BACKGROUND: Knowledge regarding factors that influence deviation of the QRS axis is important when seeking to differentiate between physiological and pathological changes. We hypothesised that, in contrast to those patients with an atrioventricular septal defect and common atrioventricular junction permitting only atrial shunting, those associated with ventricular shunting would show no relationship between the positions of the papillary muscles and the degree of the leftward deviation of the QRS axis. METHODS: We compared the positions of endocardial origin of the papillary muscles, and the frontal plane QRS axis, in patients with atrioventricular septal defects and common atrioventricular junction permitting exclusively atrial as opposed to atrial and ventricular shunting. RESULTS: We analysed 18 patients with atrial and ventricular shunting and 23 patients with exclusively atrial shunting. The correlation coefficient between the ratio of distances of the papillary muscles from the mid-septum and the amount of leftward deviation in the frontal plane QRS axis was 0.1 (p=0.4) in those with ventricular shunting and 0.26 (p=0.01) in those with exclusively atrial shunting. CONCLUSIONS: In contrast to patients with the so-called primum form of atrioventricular septal defect, in whom the locations of the papillary muscles correlate with the degree of QRS axis, such relationships are lacking in patients with defects permitting both atrial and ventricular shunting. It may be, therefore, that the presence of ventricular shunting and/or their younger age causes pressure overload, which negates the leftward QRS forces caused by the abnormally positioned papillary muscles.

The ability of mitral papillary muscle positions to explain QRS complex characteristics in humans.

Anatomical location of the conduction system may influence the characteristics of the depolarization and thus characteristics of the QRS complex. It is known that in the heart, there are electro-anatomical relationships, such as relationships among the molecular, genetic and anatomic components of the conduction system and papillary muscles. This review aims to discuss how knowledge of the electro-anatomical developmental relationships helps in understanding the known variability to be observed in the human electrocardiograms.

Multi-Modal in Vitro Experiments Mimicking the Flow Through a Mitral Heart Valve Phantom.

PURPOSE: Fluid-structure interaction (FSI) models are more commonly applied in medical research as computational power is increasing. However, understanding the accuracy of FSI models is crucial, especially in the context of heart valve disease in patient-specific models. Therefore, this study aimed to create a multi-modal benchmarking data set for cardiac-inspired FSI models, based on clinically important parameters, such as the pressure, velocity, and valve opening, with an in vitro phantom setup. METHOD: An in vitro setup was developed with a 3D-printed phantom mimicking the left heart, including a deforming mitral valve. A range of pulsatile flows were created with a computer-controlled motor-and-pump setup. Catheter pressure measurements, magnetic resonance imaging (MRI), and echocardiography (Echo) imaging were used to measure pressure and velocity in the domain. Furthermore, the valve opening was quantified based on cine MRI and Echo images. RESULT: The experimental setup, with 0.5% cycle-to-cycle variation, was successfully built and six different flow cases were investigated. Higher velocity through the mitral valve was observed for increased cardiac output. The pressure difference across the valve also followed this trend. The flow in the phantom was qualitatively assessed by the velocity profile in the ventricle and by streamlines obtained from 4D phase-contrast MRI. CONCLUSION: A multi-modal set of data for validation of FSI models has been created, based on parameters relevant for diagnosis of heart valve disease. All data is publicly available for future development of computational heart valve models.

Validation of fluid-structure interaction simulations of the opening phase of phantom mitral heart valves under physiologically inspired conditions.

BACKGROUND AND OBJECTIVE: Atrioventricular valve disease is a common cause of heart failure, and successful surgical or interventional outcomes are crucial. Patient-specific fluid-structure interaction (FSI) modeling may provide valuable insights into valve dynamics and guidance of valve repair strategies. However, lack of validation has kept FSI modeling from clinical implementation. Therefore, this study aims to validate FSI simulations against in vitro benchmarking data, based on clinically relevant parameters for evaluating heart valve disease. METHODS: An FSI model that mimics the left heart was developed. The domain included a deformable mitral valve of different stiffnesses run with different inlet velocities. Five different cases were simulated and compared to in vitro data based on the pressure difference across the valve, the valve opening, and the velocity in the flow domain. RESULTS: The simulations underestimate the pressure difference across the valve by 6.8-14 % compared to catheter measurements. Evaluation of the valve opening showed an underprediction of 5.4-7.3 % when compared to cine MRI, 2D Echo, and 3D Echo data. Additionally, the simulated velocity through the valve showed a 7.9-8.4 % underprediction in relation to Doppler Echo measurements. Qualitative assessment of the velocity profile in the ventricle and the streamlines of the flow in the domain showed good agreement of the flow behavior. CONCLUSIONS: Parameters relevant to the diagnosis of heart valve disease estimated by FSI simulations showed good agreement when compared to in vitro benchmarking data, with differences small enough not to affect the grading of heart valve disease. The FSI model is thus deemed good enough for further development toward patient-specific cases.

Mitral valve repair using leaflet expansion and subpartial annuloplasty in children.

Objective: Mitral valve reconstruction in the pediatric population is a challenge due to the frequent combination of annular dilatation and leaflet restriction and the need for growth. We present a novel strategy using leaflet expansion and subpartial annuloplasty with polytetrafluoroethylene reinforcement. Methods: From January 2014 through May 2021, 11 children aged 5 months to 14 years (median, 24 months) underwent elective mitral valve repair due to severe mitral valve regurgitation. The mitral valve abnormalities included congenital malformations (n = 7), postoperative leakage following commissurotomy (n = 1), and functional mitral valve regurgitation due to dilated cardiomyopathy (n = 3). Surgery consisted of leaflet expansions with autologous, untreated pericardium and subpartial annuloplasty with polytetrafluoroethylene reinforcement. Results: All children survived their surgeries with uneventful postoperative courses, except for 1 patient who needed an early reoperation to resolve a functional stenosis due to a spinnaker phenomenon. At discharge, mean gradient was 3.5 ± 3.9 mm Hg, with trivial mitral regurgitation in 9 patients (82%). All patients were alive and asymptomatic during the median follow-up of 3 years (range, 1-7 years). Their echocardiographic data showed a mean transmitral gradient of 4.4 ± 1.7 mm Hg and remained unchanged. Residual mitral valve regurgitation was trivial or mild in 9 patients (82%) and moderate in 2 patients (18%). Conclusions: Leaflet expansion with autologous pericardium and subpartial annuloplasty with polytetrafluoroethylene reinforcement for mitral regurgitation in the pediatric population gives stable and satisfactory results both early and at intermediate follow-up, permitting growth of the mitral valve.

Relationships between cardiac magnetic resonance imaging abnormalities in the inter-ventricular septum and Selvester QRS scoring criteria for anterior-septal myocardial infarction in patients with right ventricular volume overload.

BACKGROUND: Patients with ostium secundum atrial septal defects (ASDs) were studied to determine the prevalence of Selvester anteroseptal myocardial infarction QRS points, and to test the hypothesis that there is a relationship between these criteria and thinning and/or scarring of the inter-ventricular septum (IVS). METHODS: Demographic, electrocardiographic (ECG), and cardiac magnetic resonance imaging (CMR) data were acquired on 46 patients with a secundum ASD closed percutaneously. Selvester QRS scoring on patient ECGs was performed for areas representing the anteroseptal region of the left ventricle (LV). The IVS to LV free wall thickness ratio was used to assess thinning of the IVS while late gadolinium enhancement (LGE) of the IVS was used for scarring; both using CMR. RESULTS: Twenty-four (52%) patients scored Selvester QRS points in the anteroseptal region with a mean score of 2.6±1.8. The mean IVS/LV free wall thickness ratio at the basal level and mid-ventricular level was 1.1±0.3 and 1.3±0.3, respectively. There was no association of Selvester QRS points with IVS/LV free wall ratio at the basal (p=0.59) or mid-ventricular (p=0.13) levels. The one patient with LGE in the IVS had 4 Selvester anteroseptal QRS points. CONCLUSION: The results of our study demonstrate that in our patient population there is a 52% prevalence of Selvester anteroseptal QRS points which are due to thinning and/or scarring of the IVS in only one patient.

Reoperations After Repair for Atrioventricular Septal Defects: >25 Years Experience at a Single Center.

Our aim was to evaluate the total burden of reoperations after previous repair for atrioventricular septal defects, including long-term survival and identify risk factors for reoperation. All patients with surgical correction for atrioventricular septal defect (AVSD) 1993- 2020 underwent a follow-up in October 2020. Clinical data were obtained by retrospective review and evaluated with Kaplan-Meier and competing risk analysis. Of 477 patients who underwent initial repair, 53 patients (11.1%) underwent a total of 82 reoperations. The perioperative mortality at reoperation was 3.8% (2/53). There were no late deaths (0/51) during follow-up. In patients requiring reoperation for left atrioventricular valve regurgitation, a re-repair was performed in 90% (26/29) at first attempt. Estimated overall survival was 96.2 ± 2.6% (95% CI 91.2-100) in the Any reoperation group and 96.7 ± 0.9% (95% CI 94.9-98.5) in the No reoperation group at 20 years (P = 0.80). The cumulative incidence function of Any reoperation (with death as competing risk) was 13.0% (95% CI 9.4-16.5) at 20 years. Independent risk factors for Any reoperation included severe mitral regurgitation after primary repair (HR 40.7; 95% CI 14.9-111; P < 0.001). The risk of perioperative mortality in AVSD patients undergoing reoperation was low in the present study. Long-term survival was very good and not significantly different when compared to patients who did not need reoperation. Re-repair for left atrioventricular valve regurgitation was possible in most cases and showed long-term durability. Our data suggest that reoperations after primary repair of AVSD have very good long-term outcomes when performed at a high-volume pediatric cardiac surgery center.

Computer-based rhythm diagnosis and its possible influence on nonexpert electrocardiogram readers.

BACKGROUND: Systems providing computer-based analysis of the resting electrocardiogram (ECG) seek to improve the quality of health care by providing accurate and timely automatic diagnosis of, for example, cardiac rhythm to clinicians. The accuracy of these diagnoses, however, remains questionable. OBJECTIVES: We tested the hypothesis that (a) 2 independent automated ECG systems have better accuracy in rhythm diagnosis than nonexpert clinicians and (b) both systems provide correct diagnostic suggestions in a large percentage of cases where the diagnosis of nonexpert clinicians is incorrect. METHODS: Five hundred ECGs were manually analyzed by 2 senior experts, 3 nonexpert clinicians, and automatically by 2 automated systems. The accuracy of the nonexpert rhythm statements was compared with the accuracy of each system statement. The proportion of rhythm statements when the clinician's diagnoses were incorrect and the systems instead provided correct diagnosis was assessed. RESULTS: A total of 420 sinus rhythms and 156 rhythm disturbances were recognized by expert reading. Significance of the difference in accuracy between nonexperts and systems was P = .45 for system A and P = .11 for system B. The percentage of correct automated diagnoses in cases when the clinician was incorrect was 28% ± 10% for system A and 25% ± 11% for system B (P = .09). CONCLUSION: The rhythm diagnoses of automated systems did not reach better average accuracy than those of nonexpert readings. The computer diagnosis of rhythm can be incorrect in cases where the clinicians fail in reaching the correct ECG diagnosis.

Impact of concomitant complex cardiac anatomy in nonsyndromic patients with complete atrioventricular septal defect.

OBJECTIVE: We studied a cohort of patients with nonsyndromic complete atrioventricular septal defect with and without concomitant complex cardiac anatomy and compared the outcomes after surgical repair. METHODS: Between 1993 and 2018, 62 nonsyndromic patients underwent complete atrioventricular septal defect repair. Sixteen patients (26%) had complex complete atrioventricular septal defect with variables representing concomitant cardiac anatomic complexity: tetralogy of Fallot, double outlet right ventricle, total anomalous pulmonary venous return, concomitant aortic arch reconstruction, multiple ventricular septal defects, staged repair of coarctation of the aorta, and a persisting left superior vena cava. The mean follow-up was 12.7 ± 7.9 years. Baseline variables were retrospectively evaluated and analyzed using univariable logistic regression. Survival was studied using Kaplan-Meier estimates, and group comparisons were performed using the log-rank test. A competing-risk analysis estimated the risk of reoperation with death as the competing event. A Gray's test was used to test equality of the cumulative incidence curves between groups. RESULTS: The perioperative mortality was 3.2% (2/62). Actuarial survival was 100% versus 66.7% ± 14.9% at 10 years in the noncomplex and complex groups, respectively (P < .01). There was no significant difference in the overall reoperation rate between the noncomplex group (7/46; 15%) and the complex group (4/16; 25%) (odds ratio, 1.86; 95% confidence interval, 0.46-7.45; P = .30). The competing-risk analysis demonstrated no significant difference in reoperation between the groups (P = .28). CONCLUSIONS: Our data show that nonsyndromic patients without complex cardiac anatomy have a good long-term survival and an acceptable risk of reoperation similar to contemporary outcomes for patients with complete atrioventricular septal defect with trisomy 21. However, the corresponding group of nonsyndromic patients with concomitant complex cardiac lesions are still a high-risk population, especially regarding mortality.

Importance of standardized assessment of late gadolinium enhancement for quantification of infarct size by cardiac magnetic resonance: implications for comparison with electrocardiogram.

BACKGROUND: Cardiac magnetic resonance (CMR) is currently considered the reference standard for in vivo assessment of myocardial infarction (MI). There is, however, no international consensus on how MI quantification from CMR should be performed. The aim of this study was to test how previously published manual quantification of MI using CMR images compares with MI quantification using a semiautomated, validated method and how this impacts the relationship with MI size estimated by 12-lead electrocardiogram (ECG). METHODS: Twenty-five patients, from a previously published cohort, were included in the study. All patients had presented with clinical signs of acute coronary syndrome 6 to 12 months before undergoing a CMR examination. The patients had a standard 12-lead ECG recorded at the time of the CMR examination. The previously reported manually quantified MI size was compared with MI size determined using a semiautomated method validated by computer phantom data, experimental in vivo and ex vivo data, and patient data. The MI sizes from the 2 CMR approaches were then compared with the ECG-estimated MI size. RESULTS: There was a strong correlation between MI size determined with the 2 CMR methods (r(2) = 0.94, P < .001). There was, however, a systematic overestimation of MI size of approximately 50% by the previously published manually quantified MI size compared with the semiautomated method. This affected the comparison with estimated MI size by ECG, which showed a significant underestimation of MI size compared with manual CMR measurements, but no bias compared with the semiautomated CMR method. CONCLUSIONS: Manual quantification of MI size by CMR can differ significantly from semiautomated, validated methods taking partial volume effects into account and can lead to erroneous conclusions when compared with ECG.

Modeling vectorcardiograms based on left ventricle papillary muscle position.

BACKGROUND: Vectorcardiographic QRS loops illustrate the electrical activation of the left ventricle (LV) in 3-dimensional space; however, the individual variability in these loops is not well understood. The left bundle-branch fan distributes the initial activation to the LV and has been shown to distribute its fascicles between the LV papillary muscles. Computer models of LV activation using papillary muscle as the initial electrical activation points accurately predict QRS duration and frontal plane axis. METHODS: Twelve healthy adults received standard 12-lead electrocardiograms and 1.5-T cardiac magnetic resonance imaging. A software developed by ECG-TECH Corp (Huntington Station, NY) generated 3-dimensional QRS vector loops for each subject. Short- and long-axis papillary muscle positions were measured for each subject using cardiac magnetic resonance images. A theoretical plane equidistant from the endocardial origins of each papillary muscle was constructed. Vectors perpendicular to the QRS vector loop and the theoretical plane termed the plane identifier were used for comparison. Spearman rank correlation was used to compare the azimuth and elevation of the plane identifiers of the QRS vector loop and the theoretical plane. RESULTS: No correlation was found between the azimuth or elevation of the theoretical plane and the QRS vector loops with Spearman rank correlation coefficients of ρ = 0.11 (P = .71) and ρ = 0.22 (P = .49), respectively. Subgroup analysis by QRS vector loop morphology (planar vs nonplanar, narrow vs wide) also demonstrated no correlation. CONCLUSIONS: Modeling the activation of the LV based on papillary muscle position alone may be overly simplistic. Better understanding of what other factors contribute to individual variation in LV activation will help develop a more useful theoretical model.

Long-term outcome after early repair of complete atrioventricular septal defect in young infants.

OBJECTIVE: The long-term outcome after repair of complete atrioventricular septal defect in young infants is still not fully understood. The objective of this study was to evaluate data after repair for complete atrioventricular septal defect over a 25-year period to assess survival and identify risk factors for left atrioventricular valve-related reoperations. METHODS: A total of 304 consecutive patients underwent surgical correction for complete atrioventricular septal defect between April 1993 and October 2018. The results for young infants (aged <3 months; n = 55; mean age 1.6 ± 0.6 months) were compared with older infants (aged >3 months; n = 249; mean age, 5.1 ± 5.2 months). Mean follow-up was 13.2 ± 7.8 years (median, 14.0 years; interquartile range, 7.0-20.0). The Kaplan-Meier method was used to assess overall survival and freedom from left atrioventricular valve-related reoperation. RESULTS: Overall, 30-day mortality was 1.0% (3/304) with no difference between young and older infants (P = 1.0). Overall survival in the total population at 20-year follow-up was 95.1% (±1.3%). Independent risk factors for poor survival were the presence of an additional ventricular septal defect (P = .042), previous coarctation of the aorta (P < .001), persistent left superior vena cava (P = .026), and genetic syndromes other than Trisomy 21 (P = .017). Freedom from left atrioventricular valve-related reoperation was 92.6% (±1.7%) at 20 years. There was no significant difference in left atrioventricular valve-related reoperation in young infants compared with older infants (P = .084). CONCLUSIONS: Our data demonstrated that excellent long-term survival could be achieved with early repair for complete atrioventricular septal defect, and the need for reoperations due to left atrioventricular valve regurgitation was low. Primary correction in patients aged less than 3 months is, when clinically necessary, well tolerated. Palliative procedures can be avoided in the majority of patients.

Aspects of left ventricular morphology outperform left ventricular mass for prediction of QRS duration.

BACKGROUND: The knowledge of the case-specific normal QRS duration in each individual is needed when determining the onset, severity and progression of the heart disease. However, large interindividual variability even of the normal QRS duration exists. The aims of the study were to develop a model for prediction of normal QRS complex duration and to test it on healthy individuals. METHODS: The study population of healthy adult volunteers was divided into a sample for development of a prediction model (n = 63) and a testing sample (n = 30). Magnetic resonance imaging data were used to assess anatomical characteristics of the left ventricle: the angle between papillary muscles (PM(A)), the length of the left ventricle (LV(L)) and left ventricular mass (LV(M)). Twelve-lead electrocardiogram (ECG) was used for measurement of the QRS duration. Multiple linear regression analysis was used to develop a prediction model to estimate the QRS duration. The accuracy of the prediction model was assessed by comparing predicted with measured QRS duration in the test set. RESULTS: The angle between PM(A) and the length of the LV(L) were statistically significant predictors of QRS duration. Correlation between QRS duration and PM(A) and LV(L) was r = 0.57, P = 0.0001 and r = 0.45, P = 0.0002, respectively. The final model for prediction of the QRS was: QRS(Predicted)= 97 + (0.35 x LV(L)) - (0.45 x PM(A)). The predicted and real QRS duration differed with median 1 ms. CONCLUSIONS: The model for prediction of QRS duration opens the ability to predict case-specific normal QRS duration. This knowledge can have clinical importance, when determining the normality on case-specific basis.

Electrophysiologic and anatomical relationships studied in primum atrioventricular septal defect.

Anatomy and pattern of electrical activation predict the function and contraction pattern of the heart. Patients with primum atrioventricular septal defect (primum AVSD) present with abnormality of both anatomical arrangements and electric activation and serve therefore as an interesting population for studying electro-anatomic relationships in the heart. Understanding the relationships between anatomic and electrophysiologic abnormality is appropriate not only for diagnosis, therapy, and prognosis in patients with primum AVSD but also for understanding the developmental relationship between the conduction system and heart structures, in general. This article presents a review of the anatomical and electrophysiologic characteristics of patients with primum AVSD and provides recent knowledge of electroanatomical relationships of the heart.

The utility of modified Butler-Leggett criteria for right ventricular hypertrophy in detection of clinically significant shunt ratio in ostium secundum-type atrial septal defect in adults.

BACKGROUND: This study was performed to test the hypothesis that there exists a correlation between the Butler-Leggett (BL) criterion for right ventricular hypertrophy on the electrocardiogram and the Qp/Qs shunt ratio in adults with ostium secundum atrial septal defects (ASDs). METHODS: Demographic, cardiac catheterization, ASD closure, and electrocardiographic data were acquired on 70 patients with secundum ASDs closed percutaneously. Simple linear regression and logistic regression models were created to test the hypothesis. RESULTS: The mean Qp/Qs ratio and BL criterion value were 1.61 +/- 0.46 and 0.11 +/- 0.41, respectively. The BL criterion values correlated with shunt ratios (r(2) = 0.11 and P = .004). A BL criterion value greater than 0 mV predicted a significant shunt ratio (Qp/Qs > or = 1.5) (odds ratio, 4.8; 95% confidence interval, 1.3, 18.1; P = or <.0001) with a sensitivity of 0.68 and specificity of 0.65. CONCLUSION: Our results indicate that there is limited utility of the BL criterion at detecting right ventricular volume overload, although a BL criterion value greater than 0 mV being used to identify patients with significant intracardiac shunts yielded a sensitivity of 0.68 and specificity of 0.65.

Simulation of the QRS complex using papillary muscle positions as the site of early activation in human subjects.

BACKGROUND: Simulation of the electrical activation of the heart and its comparison with real in vivo activation is a promising method in testing potential determinants of excitation. Simulation of the electrical activity of the human heart is now emerging as a step forward for understanding and predicting electrophysiologic patterns in humans. Initial points of excitation and the manner in which the activation spreads from these points are important variables determining QRS complex characteristics. It has been suggested that in humans, the initial excitation of the left ventricle is a primary determinant of QRS complex characteristics, and that excitation begins at the papillary muscles and septum, where the fascicles of the left bundle branch insert. The aim of this study is to test the hypothesis that QRS duration and direction of QRS axis in the frontal plane have excellent agreement between real QRS and simulated QRS using papillary muscle position to indicate the border of the origin of early ventricular activation. METHODS: Fourteen healthy adult volunteers were included in the study. Magnetic resonance imaging data were obtained to assess the papillary muscle positions. Twelve-lead electrocardiographic (ECG) recordings were used to obtain real ECG data for assessment of QRS duration and QRS axis in each subject. Simulation software developed by ECG-TECH Corp (Huntington, NY) was used to simulate the ECG of each subject to determine simulated QRS duration and QRS frontal plane axis. QRS duration and QRS axis data were compared between simulated and real ECG and agreement between these variables was calculated. RESULTS: Seventy-nine percent of subjects had a difference of the QRS duration between real and simulated ECG of less than 10 milliseconds. The calculated strength of agreement between simulated and real QRS duration was 71% and considered as "good" (kappa statistics). In 70% of subjects, the difference in the QRS axis was less than 10 degrees . The calculated strength of agreement between simulated and real QRS axis was 80% and considered as "excellent" (kappa statistics). CONCLUSIONS: The results of this study suggest that the sites of the initiation of electrical activity in the left ventricle, as assessed by the positions of papillary muscles, may be considered as primary determinants of the QRS duration and QRS axis in humans. This knowledge may help in predicting normal QRS characteristic on a patient-specific basis. In this study, simulation of the QRS complex was based on papillary muscles from human hearts.