Variations in the Evaluation and Management of Vascular Rings: A Survey of American Clinicians.

Vascular rings are arterial malformations that lead to the compression of the trachea and/or esophagus. While "tight" rings often produce symptoms and require surgery, "loose" rings rarely produce symptoms. Given advances in fetal echocardiography, this diagnosis is now more often made prenatally. This poses a new conundrum in the management of asymptomatic patients, leading to practice variation and creating a target for clinical system improvement. Hence, we conducted this survey aiming to demonstrate the practice variation existing in current evaluation and management of these patients. An anonymous web-based survey was distributed to several listservs for pediatric cardiologists and pediatric cardiothoracic surgeons. Survey questions targeted respondent practice characteristics, testing obtained, and indications for testing or surgical referral. In total 61 responses were received, predominantly from pediatric cardiologists (95%) in the United States (97%). About 60% of clinicians reported frequently diagnosing patients with vascular rings by fetal echocardiogram, with only about 20% diagnosing them frequently on evaluation of symptoms. Computed tomography angiography and echocardiogram were the most common imaging modalities employed. Most clinicians obtained cross-sectional imaging at the time of diagnosis and referred to surgery once patients had at least occasional symptoms. Respondents demonstrated a low degree of agreement (Krippendorf's alpha 0.48). Few statistically significant patterns were identified between respondents based on their practice characteristics. This study identified significant variation between clinicians regarding the evaluation and management of vascular rings. Further research or expert opinions may help to standardize practice, saving costs and improving the quality of care for affected patients.

Real-Time Artificial Intelligence-Based Guidance of Echocardiographic Imaging by Novices: Image Quality and Suitability for Diagnostic Interpretation and Quantitative Analysis.

BACKGROUND: We aimed to assess in a prospective multicenter study the quality of echocardiographic exams performed by inexperienced users guided by a new artificial intelligence software and evaluate their suitability for diagnostic interpretation of basic cardiac pathology and quantitative analysis of cardiac chamber and function. METHODS: The software (UltraSight, Ltd) was embedded into a handheld imaging device (Lumify; Philips). Six nurses and 3 medical residents, who underwent minimal training, scanned 240 patients (61±16 years; 63% with cardiac pathology) in 10 standard views. All patients were also scanned by expert sonographers using the same device without artificial intelligence guidance. Studies were reviewed by 5 certified echocardiographers blinded to the imager's identity, who evaluated the ability to assess left and right ventricular size and function, pericardial effusion, valve morphology, and left atrial and inferior vena cava sizes. Finally, apical 4-chamber images of adequate quality, acquired by novices and sonographers in 100 patients, were analyzed to measure left ventricular volumes, ejection fraction, and global longitudinal strain by an expert reader using conventional methodology. Measurements were compared between novices' and experts' images. RESULTS: Of the 240 studies acquired by novices, 99.2%, 99.6%, 92.9%, and 100% had sufficient quality to assess left ventricular size and function, right ventricular size, and pericardial effusion, respectively. Valve morphology, right ventricular function, and left atrial and inferior vena cava size were visualized in 67% to 98% exams. Images obtained by novices and sonographers yielded concordant diagnostic interpretation in 83% to 96% studies. Quantitative analysis was feasible in 83% images acquired by novices and resulted in high correlations (r≥0.74) and small biases, compared with those obtained by sonographers. CONCLUSIONS: After minimal training with the real-time guidance software, novice users can acquire images of diagnostic quality approaching that of expert sonographers in most patients. This technology may increase adoption and improve accuracy of point-of-care cardiac ultrasound.

An unusual case of a solitary cardiac myofibroma causing severe right ventricular outflow tract obstruction in an infant.

Cardiac tumours are relatively uncommon, particularly in children. Myofibroma is an extremely rare variety of cardiac tumour, which nearly always arises in the context of infantile myofibromatosis. Herein, we present a case of a solitary cardiac myofibroma causing right ventricular outflow tract obstruction in a 2-month-old male infant.

Left Ventricular Mass Quantification by Two-Dimensional Echocardiography in a Pediatric Population: Correlation with Cardiac Magnetic Resonance Imaging.

Quantification of left ventricular (LV) mass by echocardiography has not been validated against the gold standard of cardiac magnetic resonance imaging (CMR) in the pediatric population. The purpose of this study was to compare LV mass by two-dimensional and conventional M-mode echocardiography versus CMR in children. Consecutive CMR studies were paired with echocardiograms and retrospectively analyzed in children age ≤ 16 years (3 days old to 16 years old). Studies performed > 3 months between modalities and single ventricle anatomy were excluded. Unindexed LV mass was calculated using M-mode, area-length (AL), and truncated ellipsoid (TE) methods via echocardiography, and compared to cine stack CMR images. There were 46 patients included in the study (both MRI and echocardiography). Good correlations were observed for LV mass measured by CMR and all echocardiographic methods: M-mode (R = 0.965), AL (R = 0.975), and TE (R = 0.975). There was a significant overestimation using TE echocardiography, by a mean of 10.5 g (95% confidence interval 5.7-15.2 g, p < 0.05). There was no significant over- or underestimation of LV mass observed by M-mode or AL echocardiographic measurements, with tight limits of agreement when compared to CMR (95% confidence interval - 5.2 to 4.4 g and - 1.5 to 6.7 g, respectively). Interobserver agreement was good for each of the echocardiographic measurements, but inferior with M-mode (ICC, 0.89) compared to two-dimensional methods (ICC, 0.97). Echocardiographic estimates of LV mass have good correlation with CMR in children. Performance comparison showed AL echocardiographic method provides the most accurate measurement of LV mass with the best reproducibility compared to other methods.

A prospective case series evaluating use of an in-line air detection and purging system to reduce air burden during major surgery.

BACKGROUND: Intravascular air embolism (AE) is a preventable but potentially catastrophic complication caused by intravenous tubing, trauma, and diagnostic and surgical procedures. The potentially fatal risks of arterial AE are well-known, and emerging evidence demonstrates impact of venous AEs on inflammatory response and coagulation factors. A novel FDA-approved in-line air detection and purging system was used to detect and remove air caused by administering a rapid fluid bolus during surgery. METHODS: A prospective, randomized, case series was conducted. Subjects were observed using standard monitors, including transesophageal echocardiography (TEE) in the operating room. After general anesthesia was induced, an introducer and pulmonary artery catheter was inserted in the right internal jugular to administer fluids and monitor cardiac pressures. Six patients undergoing cardiac surgery were studied. Each patient received four randomized fluid boluses: two with the in-line air purging device, two without. For each bolus, a bulb infuser was squeezed three times (10-15 mL) over 5 s. The TEE was positioned in the mid-esophageal right atrium (RA) to quantify peak air clearance, and images were video recorded throughout each bolus. Air was quantified using optical densitometry (OD) from images demonstrating maximal air in the RA. RESULTS: All subjects demonstrated significantly lower air burden when the air reduction device was used (p = 0.004), and the average time to clear 90% of air was also lower, 3.7 ± 1.2 s vs. 5.3 ± 1.3 s (p < 0.001). CONCLUSION: An air purging system reduced air burden from bolus administration and could consequently reduce the risk of harmful or fatal AEs during surgery.

A central role of plasmin in cardiac injury initiated by fetal exposure to maternal anti-Ro autoantibodies.

OBJECTIVE: Cardiac neonatal lupus (cardiac-NL), initiated by surface binding of anti-Ro60 autoantibodies to apoptotic cardiocytes during development, activates the urokinase plasminogen activator/urokinase plasminogen activator receptor (uPA/uPAR) system. Subsequent accumulation of apoptotic cells and plasmin generation facilitates increased binding of anti-Ro60 by disrupting and cleaving circulating ß2-glycoprotein I (ß2GPI) thereby eliminating its protective effect. The association of soluble levels of components of the uPA/uPAR system with cardiac-NL was examined. METHODS: Levels of the uPA/uPAR system were assessed by ELISA in cord blood and immunohistological evaluation of autopsies. RESULTS: uPA, uPAR and plasminogen levels were each significantly higher in cord blood from cardiac-NL (n = 35) compared with non-cardiac-NL (n = 26) anti-Ro-exposed neonates: 3.3 ± 0.1 vs 1.9 ± 0.05 ng/ml (P < 0.0001), 6.6 ± 0.3 vs 2.1 ± 0.2 ng/ml (P < 0.0001) and 435 ± 34 vs 220 ± 19 ng/ml (P < 0.0001), respectively. In three twin pairs discordant for cardiac-NL, the twin with cardiac-NL had higher levels of uPA, uPAR and plasminogen than the unaffected twin (3.1 ± 0.1 vs 1.9 ± 0.05 ng/ml; P = 0.0086, 6.2 ± 1.4 vs 2.2 ± 0.7 ng/ml; P = 0.147 and 412 ± 61 vs 260 ± 27 ng/ml; P = 0.152, respectively). Immunohistological evaluation of three hearts from fetuses dying with cardiac-NL revealed macrophages and giant cells expressing uPA and plasminogen in the septal region. CONCLUSION: Increased soluble uPA, uPAR and plasminogen in cord blood and expression in affected tissue of fetuses with cardiac-NL supports the hypothesis that fetal cardiac injury is in part mediated by plasmin generation initiated by anti-Ro binding to the apoptotic cardiocyte.

Accuracy and reproducibility of strain by speckle tracking in pediatric subjects with normal heart and single ventricular physiology: a two-dimensional speckle-tracking echocardiography and magnetic resonance imaging correlative study.

BACKGROUND: Myocardial strain is a sensitive measure of ventricular systolic function. Two-dimensional speckle-tracking echocardiography (2DSE) is an angle-independent method for strain measurement but has not been validated in pediatric subjects. The aim of this study was to evaluate the accuracy and reproducibility of 2DSE-measured strain against reference tagged magnetic resonance imaging-measured strain in pediatric subjects with normal hearts and those with single ventricles (SVs) of left ventricular morphology after the Fontan procedure. METHODS: Peak systolic circumferential strain and longitudinal strain (LS) in segments (n = 16) of left ventricles in age-matched and body surface area-matched 20 healthy and 12 pediatric subjects with tricuspid atresia after the Fontan procedure were measured by 2DSE and tagged magnetic resonance imaging. Average (global) and regional segmental strains measured by the two methods were compared using Spearman's and Bland-Altman analyses. RESULTS: Global strains measured by 2DSE and tagged magnetic resonance imaging demonstrated close agreements, which were better for LS than circumferential strain and in normal left ventricles than in SVs (95% limits of agreement, +0.0% to +3.12%, -2.48% to +1.08%, -4.6% to +1.8%, and -3.6% to +1.8%, respectively). There was variability in agreement between regional strains, with wider limits in apical than in basal regions in normal left ventricles and heterogeneity in SVs. Strain values were significantly (P < .05) higher in normal left ventricles than in SVs except for basal LS, which were similar in both cohorts. The regional strains in normal left ventricles demonstrated an apicobasal magnitude gradient, whereas SVs showed heterogeneity. Reproducibility was the most robust for images obtained with frame rates between 60 and 90 frames/sec, global LS in both cohorts, and basal strains in normal left ventricles. CONCLUSIONS: Strains measured by 2DSE agree with strain measured by magnetic resonance imaging globally but vary regionally, particularly in SVs. Global strain may be a more robust tool for cardiac functional evaluation than regional strain in SV physiology. The reliability of 2DSE-measured strain is affected by the frame rate, the nature of strain, and ventricular geometry.

Intrinsic myoarchitectural differences between the left and right ventricles of fetal human hearts: an ultrasonic backscatter feasibility study.

OBJECTIVE: Embryologically, cardiac chambers differ in their morphologic and contractile properties from the beginning. We hypothesized that a noninvasive ultrasonic backscatter investigation might illustrate the fundamental differences in myocardial morphologic properties of the 2 ventricles during heart development. The goals of this investigation were to 1) explore the feasibility of measuring the magnitude of cyclic variation of ultrasonic backscatter from the left and right ventricular free walls of fetal hearts; 2) compare measurements of the magnitude of cyclic variation from the left and right sides of the heart; and 3) determine if the observed results are consistent with predictions relating the overall backscatter level and the magnitude of cyclic variation. METHODS: Cyclic variation data from the left and right ventricular free walls were generated from analyses of the backscatter from echocardiographic images of 16 structurally normal fetal hearts at mid-gestation. RESULTS: The magnitude of cyclic variation was found to be greater for the left ventricular free wall than for the right ventricular free wall (4.5 +/- 1.1 dB vs 2.3 +/- 0.9 dB, respectively; mean +/- standard deviation; P < .0001, paired t test). CONCLUSION: Measurements of the cyclic variation of backscatter can be obtained from both the left and right sides of fetal hearts demonstrating a significant difference between the measured magnitude of cyclic variation in the left and right ventricular myocardium. This observation is consistent with predictions relating the overall backscatter level and the magnitude of cyclic variation. The results of this study suggest cyclic variation measurements may offer a useful approach for characterizing intrinsic differences in myocardial properties of the 2 ventricles in assessing fetal heart development.

Measurements of ultrasonic attenuation properties of midgestational fetal pig hearts.

The objectives of this study were to measure the relative attenuation properties of the left and right ventricles in fetal pig hearts and to compare the spatial variation in attenuation measurements with those observed in previously published backscatter measurements. Approximately 1.0-mm-thick, short-axis slices of excised, formalin-fixed heart were examined from 15 midgestational fetal pigs using a 50-MHz single-element transducer. Measurements of the attenuation properties demonstrate regional differences in the left and right ventricular myocardium that appear consistent with the previously reported regional differences in apparent integrated backscatter measurements of the same fetal pig hearts. For regions of perpendicular insonification relative to the myofiber orientation, the right ventricular free wall showed larger values for the slope of the attenuation coefficient from 30-60 MHz (1.48 +/- 0.22 dB/(cm x MHz) (mean +/- SD) and attenuation coefficient at 45 MHz (46.3 +/- 7.3 dB/cm [mean +/- SD]) than the left ventricular free wall (1.18 +/- 0.24 dB/(cm x MHz) and 37.0 +/- 7.9 dB/cm (mean +/- SD) for slope of attenuation coefficient and attenuation coefficient at 45 MHz, respectively). This attenuation study supports the hypothesis that intrinsic differences in the myocardium of the left and right ventricles exist in fetal pig hearts at midgestation.

Maturational and growth-related changes in left ventricular longitudinal strain and strain rate measured by two-dimensional speckle tracking echocardiography in healthy pediatric population.

OBJECTIVE: We aimed to evaluate myocardial strain and strain rate (SR) by novel 2-dimensional speckle tracking echocardiography in a large pediatric cohort (1) to establish their normal values and (2) to discern the influence of maturation and cardiac growth on them. METHODS: Echocardiograms of 284 consecutive subjects of a healthy pediatric cohort aged between birth and 18 years were analyzed by vector velocity imaging software to measure longitudinal systolic strain (epsilon) and systolic and diastolic SR in left ventricular septal and lateral segments. Regression analysis was performed to determine the effect of aging and cardiac growth on epsilon and SR. RESULTS: Longitudinal epsilon (septal -18.30% +/- 6.67% and lateral -20.68% +/- 8.08%) did not change significantly with maturation and declining heart rate from birth to 18 years. Systolic and early diastolic SR declined until age 5 to 10 years. Longitudinal epsilon significantly (P < .05) correlated with left ventricular growth. CONCLUSION: This study establishes reference values for longitudinal epsilon and SR and reveals that epsilon is relatively independent of maturational changes, lending it as a tool for cardiac evaluation across differing ages in pediatric subjects.

Regional variation in the measured apparent ultrasonic backscatter of mid-gestational fetal pig hearts.

The goal of this study was to characterize and compare regional backscatter properties of fetal hearts through measurements of the apparent integrated backscatter. Sixteen excised, formalin-fixed fetal pig hearts, representing an estimated 53 to 63 days of gestation, were investigated. Spatially localized measurements of integrated backscatter from these specimens were acquired using a 50 MHz single-element transducer. The apparent integrated backscatter measurements demonstrate different patterns of backscatter from the myocardium of the right ventricle compared with that of the left ventricle. These backscatter measurements appear to be consistent with the anisotropy of the fiber orientation observed in histologic assessment of the same specimens. For each of the 16 hearts, the apparent integrated backscatter from the right ventricular myocardium was larger than that from the left ventricular myocardium, exhibiting mean apparent backscatter values of -35.9 +/- 2.0 dB and -40.1 +/- 1.9 dB (mean +/- standard deviation; n = 16; p < 0.001), respectively. This study suggests that the intrinsic ultrasonic properties of the left and right ventricular myocardium are distinct in fetal pig hearts at mid-gestation.

Fetal cardiac rhabdomyoma: a sheep or a wolf?

Rhabdomyoma is the most common primary cardiac tumor identified in utero and in infancy. Usually it has a benign course, which has prompted an expectant approach to its management. We report herein the cases of three patients who presented prenatally with cardiac rhabdomyomas. Only one of them had a benign course. The other two patients provided recognizable characteristics of rhabdomyomas with an unfavorable course and demonstrated that fetal rhabdomyomas can have a fatal outcome.

Effect of acute changes in load on left ventricular diastolic function during device closure of atrial septal defects.

Echocardiographic indexes of left ventricular (LV) diastolic function were assessed in 18 patients before and after device closure of secundum atrial septal defects. The tissue Doppler early diastolic peak annular velocity (Ea) and color M-mode velocity of propagation (Vp), indexes of relaxation, seemed to be load independent and were not affected by the change in LV filling hemodynamics, whereas the mitral inflow peak E-wave velocity and E/Ea ratio were more load dependent, with a resultant increase after the closure of large atrial shunts.

Comparison of right ventricle to pulmonary artery conduit and modified Blalock-Taussig shunt hemodynamics after the Norwood operation.

The Norwood procedure remains one of the highest-risk operations in congenital heart surgery. A significant contributor to this risk is thought to be the diastolic run-off into the modified Blalock-Taussig shunt (MBTS). In an effort to eliminate this risk, several groups have begun to utilize a right ventricle to pulmonary artery conduit (RVPAC), which decreases this diastolic "steal" of coronary blood flow. Whereas initial results with the RVPAC are encouraging, the postulated hemodynamic advantages are unproven. This case illustrates the positive hemodynamic changes by echocardiography after the replacement of a MBTS with a RVPAC in a patient after a Norwood procedure.

Initial animal studies of a wireless, batteryless, MEMS implant for cardiovascular applications.

This paper reports the results of the initial animal studies of a wireless, batteryless, implantable pressure sensor using microelectromechanical systems (MEMS) technology. The animal studies were acute and proved the functional feasibility of using MEMS technology for wireless bio sensing. The results are very encouraging and surpassed the majority of the application's requirements, including high sampling speed and high resolution. Based on the lessons learned, second generation wireless sensors are being developed that will provide total system solution.

Controlled ultrasound tissue erosion.

The ability of ultrasound to produce highly controlled tissue erosion was investigated. This study is motivated by the need to develop a noninvasive procedure to perforate the neonatal atrial septum as the first step in treatment of hypoplastic left heart syndrome. A total of 232 holes were generated in 40 pieces of excised porcine atrial wall by a 788 kHz single-element transducer. The effects of various parameters [e.g., pulse repetition frequency (PRF), pulse duration (PD), and gas content of liquid] on the erosion rate and energy efficiency were explored. An Isppa of 9000 W/cm2, PDs of 3, 6, 12, and 24 cycles; PRFs between 1.34 kHz and 66.7 kHz; and gas saturation of 40-55% and 79-85% were used. The results show that very short pulses delivered at certain PRFs could maximize the erosion rate and energy efficiency. We show that well-defined perforations can be precisely located in the atrial wall through the controlled ultrasound tissue erosion (CUTE) process. A preliminary in vivo experiment was conducted on a canine subject, and the atrial septum was perforated using CUTE.

Can we improve the assessment of discharge readiness?: A comparative study of observational and objective measures of depth of sedation in children.

BACKGROUND: Current recommended discharge criteria might not be rigorous enough to detect residual sedation. This study evaluated the use of the Bispectral Index (BIS monitor), the University of Michigan Sedation Scale (UMSS; i.e., 0-4 observational scale), and a Modified Maintenance of Wakefulness Test (MMWT; visual observation of the time the child is able to stay awake) in assessing return to baseline status. METHODS: Twenty-nine children sedated for echocardiographic examination were studied. Nurses administered sedatives and monitored and discharged children according to institutional guidelines. Children were monitored with the BIS(R) throughout the study. Trained observers assigned UMSS scores every 10-15 min until revised discharge criteria were met (i.e., UMSS score of 0 or 1, MMWT duration >/= 20 min). The MMWT value was recorded at each observation following the procedure. Subsequently, blinded observers recorded average BIS values for the 5 min before each UMSS observation. RESULTS: There were moderate correlations between the BIS, MMWT, and UMSS scores (r = 0.68-0.78; P < 0.01). Revised criteria correctly identified children who were awake and alert (BIS value >/= 90) in 88% of the cases. Only 55% of the children had returned to baseline BIS values when discharged by the nurse, compared with 92% when revised criteria were met (P < 0.05). It took longer to meet revised criteria compared with standard criteria (75.3 +/- 76.2 min vs. 16.4 +/- 13.1 min; P = 0.001). CONCLUSIONS: The incorporation of specific, objective discharge criteria (i.e., UMSS score of 0 or 1, MMWT duration >/= 20 min) may ensure a status closer to baseline (BIS value >/= 90) compared with nursing judgment using standard criteria. However, such assurance may delay the discharge of sedated children.

Comparison of simultaneous invasive and noninvasive measurements of pressure gradients in congenital aortic valve stenosis.

PURPOSE: Congenital aortic valve stenosis is a common problem in pediatric cardiology. The catheter peak to peak systolic gradient is the accepted standard used for prognosis and intervention, but noninvasive correlation in pediatric patients is frequently associated with underestimation or overestimation of this gradient. The purpose of this study was to compare different noninvasive measurements with simultaneous catheter gradients to identify which best predicts the catheter peak to peak gradient. METHODS: Twenty-five simultaneous Doppler and catheter measurements of aortic stenosis gradient were performed in 14 children (all 14 before valvuloplasty and 11 after valvuloplasty). Noninvasive estimates of pressure gradient were compared with catheter measurements with linear regression and Bland-Altman analysis. RESULTS: The Doppler peak instantaneous pressure gradient overestimated the catheter peak to peak gradient but correlated well with the catheter peak instantaneous gradient. The Doppler mean systolic gradient correlated well with the catheter peak to peak gradient at low gradients and underestimated higher catheter gradients but agreed well at all levels with the catheter mean gradient. The modification of a catheter-derived correlation equation produced good correlation with the catheter peak to peak gradient (slope, 1.14; intercept, -1.8; R, 0.92), as did the use of estimated pressure recovery (slope, 1.04; intercept, 5.0; R, 0.94), calculated from a defined fluid mechanic equation. CONCLUSION: The catheter peak to peak gradient can be accurately estimated noninvasively using estimated pressure recovery or correlation equations incorporating Doppler measurements.