Risk Factors for Cardiac Adverse Events in Infants and Children with Complex Heart Disease Scheduled for Bi-ventricular Repair: Prognostic Value of Pre-operative B-Type Natriuretic Peptide and High-Sensitivity Troponin T.

Few reports have described the prognostic value of measuring both B-type natriuretic peptides (BNP) and high-sensitivity troponin T (hs-TnT) in pediatric patients with complex congenital heart disease (CHD) undergoing surgery. We assessed demographic, hemodynamic, and laboratory data, including BNP and hs-TnT levels, for the prediction of cardiac adverse events in 85 patients. Cardiac adverse events were defined as death, cardiac arrest, worsening heart failure requiring inotropic agents and/or respiratory support, and unscheduled surgery/intervention either within or after 12 months of surgery. There were 17 cardiac adverse events. Of the demographic variables, low birth weight (< 2500 g: Odds ratio [OR], 5.97; 95% confidential interval [CI] 1.48-24.0; p = 0.001) and Ross/New York Heart Association [NYHA] class (≥ 2.0) (OR 12.7; 95% CI 3.08-52.7; p = 0.0004) were strongly association with cardiac adverse events. Among hemodynamic and laboratory variables, preoperative BNP (OR 14.04; 95% CI 2.15-91.7; p = 0.001) and hs-TnT levels (OR 16.66; 95% CI 2.27-122; p = 0.002) were found to be independent risk factors. Receiver operating characteristic analysis determined BNP and hs-TnT levels of 60.9 pg/mL and 0.025 ng/mL, respectively, to be markers of high risk. Kaplan-Meier analysis demonstrated significant differences in the freedom from cardiac adverse events between Group A (BNP or hs-TnT elevated, n = 26) and Group B (both biomarkers elevated, n = 19; log-rank, p < 0.001). In conclusion, low birth weight (< 2500 g) and Ross/NYHA class ≥ 2.0 are strongly associated with cardiac adverse events. Preoperative BNP and hs-TnT also provide prognostic information in patients with complex CHD scheduled for surgery. Using both markers in combination predicts cardiac adverse events better than using either separately.

Liver Cirrhosis and/or Hepatocellular Carcinoma Occurring Late After the Fontan Procedure　- A Nationwide Survey in Japan.

BACKGROUND: Fontan-associated liver disease (FALD) is an important late complication involving liver dysfunction, such as liver cirrhosis (LC) and hepatocellular carcinoma (HCC), in patients undergoing the Fontan procedure. However, the prevalence, clinical manifestation, and methods of diagnosis of FALD are still not well established.Methods and Results:This study comprised 2 nationwide surveys in Japan. First, the prevalence of LC and/or HCC in patients undergoing the Fontan procedure was determined. Second, clinical manifestations in patients with LC and/or HCC were analyzed, along with data from blood tests, echocardiography, and right heart catheterization. In the 1st survey, of the 2,700 patients who underwent the Fontan procedure, 31 were diagnosed with LC and/or HCC (1.15%), and 5 died due to liver diseases (mortality: 0.19%). In the 2nd survey, data were collected from 17 patients (12 with LC, 2 with HCC, and 3 with LC+HCC. Of these 17 patients, 5 died (mortality: 29.4%). The mean age at diagnosis of LC and HCC was 23 and 31 years, respectively. Computed tomography followed by ultrasound was most frequently used for diagnosis. Blood tests revealed low platelet counts, increased hemoglobin, aspartate aminotransferase, γ-guanosine triphosphate, and total bilirubin levels, and an elevated international normalized ratio of prothrombin time. CONCLUSIONS: LC and/or HCC in patients undergoing the Fontan procedure were not rare late complications and were associated with high mortality rates.

A Variable Stiffness Soft Gripper Based on Rotational Layer Jamming.

This article presents the design and fabrication of a variable stiffness soft gripper based on layer jamming. Traditional layer jamming units have some limitations, such as complicated multistep fabrication, difficulties in system integration, and diminishing in stiffen effect. In this article, a variable stiffness soft gripper is proposed based on the rotational jamming layers to reduce the slippery phenomenon between layers. To fabricate the proposed complex design, a two-step fabrication method is presented. First, multimaterial 3D printing is applied to directly print out the soft finger body with jamming layers. Second, mold casting is used to fabricate the outer vacuum chamber. The proposed gripper contains a main framework and three identical variable stiffness soft fingers. To demonstrate the effectiveness of the design, the soft gripper is mounted on a robotic arm to test its ability of grasping heavy objects while following complex grasping trajectory. The gripper can successfully grasp an object up to 360 g. Grasping robustness of the proposed gripper can be guaranteed when the robotic arm is moving at acceleration up to 7 m/s2. The results prove that the proposed design of the soft gripper can improve the grippers grasping robustness during high-speed movement.

Survey of reoperation indications in tetralogy of fallot in Japan.

BACKGROUND: Although the survival rate for repaired Tetralogy of Fallot (TOF) is dramatically improving, anatomical and functional residua and sequelae followed by arrhythmias and sudden death are still challenging issues to be resolved. Reoperation can reduce the incidence of arrhythmias and sudden death, but there is no consensus on the indications of reoperation for patients with TOF, especially in Japan. METHODS AND RESULTS: A cross-sectional questionnaire survey of reoperation indications in patients with TOF was performed through a Japanese multicenter study. The questionnaire, which focused on the number of repaired TOF patients aged >15 years old, reoperation indications and management, was sent to the institutions belonging to Japanese Society for Adult Congenital Heart Disease. In total, 41.5% (78/188) of the institutions replied. The total number of repaired TOF patients was 4,010, and sudden cardiac death was observed in 45.236/4,010 (5.9%) experienced reoperation. Pulmonary stenosis (32%) and pulmonary regurgitation (29%) were the most common reasons for reoperation. There were only 2 implantable cardioverter defibrillator or resynchronization therapy defibrillator implantations. The physiological/anatomical indications of reoperation differed among the hospitals. CONCLUSIONS: Approximately 1.1% of patients suffered sudden death and 6% of repaired TOF patients had reoperation. The indications of reoperation, however, varied among the institutions. Therefore, detailed information for each case of sudden death or reoperation should be collected and analyzed in order to establish guidelines for reoperation.

Complications of cardiac catheterization in adults and children with congenital heart disease in the current era.

The number of adults with congenital heart disease (CHD) requiring diagnostic and/or therapeutic cardiac catheterization has been increasing. However, there have been few studies on the complications of performing cardiac catheterization in adults with CHD. The aim of this study was to determine the incidence of complications during congenital cardiac catheterization in both adults and pediatric patients. A total of 2134 consecutive cardiac catheterizations performed between 2003 and 2008 were prospectively analyzed. Complications were graded from 1 to 5 based on severity and these, with ≥ grade 3 being defined as major. During the study period, 576 procedures (393 diagnostic, 90 interventional, and 93 electrophysiological) were performed in adult patients (≥ 18 years). Complex heart disease was present in 435 of 576 procedures (75.6 %). A total of 65 complications (11.3 %) with 13 major complications including 1 death (2.3 %) were encountered. The most common complications were arrhythmias. The majority of complications were successfully treated or temporary, and all but one of the patients were without residua. Of the 1558 pediatric procedures performed during the same period, we found a total of 229 complications (14.7 %), of which 89 (5.7 %) were major complications including 5 deaths. The safety of performing cardiac catheterization for adult CHD appears to be similar to that for pediatric patients. The complication rates in adults with CHD are low, but not negligible.

Very low birth weight infants with congenital heart disease: A multicenter cohort study in Japan.

BACKGROUND: The frequency, mortality, and morbidity of very low birth weight (VLBW) infants with congenital heart disease (CHD) in Asian countries are limited. In addition, little is known about the risk factors of death in these infants. METHODS: A retrospective, multicenter cohort study was conducted. VLBW infants with CHD born between 2006 and 2010, and followed to 5 years of age, were included in the analysis. Multiple logistic regression analysis was performed to identify the risk factors of death. RESULTS: Among 3247 VLBW infants, 126 various CHDs (3.9 %) were identified. The most common lesions were ventricular septal defect, tetralogy of Fallot (TOF), and coarctation of the aorta/interrupted aortic arch, in that order. The proportions of left-sided and right-sided outflow obstruction (TOF, pulmonary stenosis) were 15.1 % and 15.9 %, respectively. Trisomy 18 and trisomy 13 were present in 32 (25.4 %) of 126 VLBW infants with CHD. Nine patients were lost to follow-up. Overall, 45 patients (35.7 %) died up to 5 years of age. Serious CHD [odds ratio (OR), 19.2; 95 % confidential interval (CI), 3.94-93.11; p < 0.0001], sepsis (OR, 42.3; 95 % CI, 5.39-332.22; p < 0.0001), chromosomal /named anomalies (OR, 7.50; 95%CI, 2.09-26.94; p = 0.001), and no-invasive treatments (OR, 9.89; 95%CI, 2.28-42.91; p = 0.001) were associated with death. On excluding chromosomal anomalies, twelve of 71 patients (16.9 %) died, and only sepsis (OR, 35.5, 95%CI, 2.63-477.1; p = 0.0008) was an independent risk factor. CONCLUSIONS: Trisomy 18 and trisomy 13 of chromosomal anomalies are frequently associated with VLBW infants with CHD. The mortality of VLBW infants with CHD is high, even when chromosomal anomalies are excluded. Sepsis has a significant impact on death in VLBW infants with CHD.

Relationship between Photoelasticity of Polyurethane and Dielectric Anisotropy of Diisocyanate, and Application of High-Photoelasticity Polyurethane to Tactile Sensor for Robot Hands.

Eight types of polyurethane were synthesized using seven types of diisocyanate. It was found that the elasto-optical constant depends on the concentration of diisocyanate groups in a unit volume of a polymer and the magnitude of anisotropy of the dielectric constant of diisocyanate groups. It was also found that incident light scattered when bending stress was generated inside photoelastic polyurethanes. A high sensitive tactile sensor for robot hands was devised using one of the developed polyurethanes with high photoelasticity.

Percutaneous transluminal coronary angioplasty for postoperative left coronary artery stenosis following surgical reconstruction of congenital atresia of the left main coronary artery.

Congenital atresia of the left main coronary ostium is a rare coronary artery anomaly. A 3-year-old boy who was asymptomatic had a heart murmur because of mitral regurgitation. He underwent reconstruction of the left main coronary artery, but stenosis occurred in the early postoperative period. Although the patient underwent repair of the coronary artery stenosis, the distal portion of the left coronary artery re-stenosed. Percutaneous transluminal coronary angioplasty for the stenosis was performed successfully and there has not been any sign of re-stenosis for 30 months to date.

A Fully Multi-Material Three-Dimensional Printed Soft Gripper with Variable Stiffness for Robust Grasping.

Multi-material three-dimensional (3D) printing has provided the possibility of direct 3D printing of soft actuators with high complexity and functionality in a fast and easy fabrication process. In this article, we present the design of a multi-material 3D printed variable stiffness soft robotic gripper to ensure grasping robustness during high acceleration. The proposed gripper contains two identical soft fingers, with each finger including a pneumatic actuator and an integrated layer jamming unit. Prototypes of the soft finger, with material hardness transfer from the soft-bodied actuator to the hard pneumatic tubing and layer jamming unit, are fully fabricated by one-step 3D printing. A multi-material 3D printer, Objet350Connex, is used to directly print out the whole finger without the need for an additional casting process. The printed soft finger has a complex inner geometry, which integrates a small, light, and flexible layer jamming unit. The proposed finger can freely deform at low stiffness and maintain its grasping robustness at high stiffness during high acceleration. To demonstrate the effectiveness of the proposed design, the gripper is mounted on a robotic arm to evaluate its grasping robustness. With the aid of the integrated layer jamming unit, grasping robustness can be guaranteed when the robotic arm is moving at acceleration up to 8 m/s2. The results show that the proposed soft gripper is an effective design, which can guarantee grasping robustness during high acceleration.

Elevated vascular endothelial growth factor levels are associated with aortopulmonary collateral vessels in patients before and after the Fontan procedure.

BACKGROUND: Aortopulmonary collaterals (APCs) are frequently observed before and after the Fontan procedure. However, the mechanism of the development of APCs is unknown. We hypothesized that one or several antiangiogenic and/or angiogenic growth factors might play a role in the development of APCs. METHODS: Eighty-five patients were enrolled and divided into 3 groups (Fontan group: 30 patients after the Fontan procedure, cyanotic group: 29 patients with cyanotic heart disease, and control group: 26 patients with cyanotic heart disease after biventricular repair). We measured basic fibroblast growth factor, vascular endothelial growth factor (VEGF), hepatocyte growth factor, and endostatin at catheterization. Angiographic evaluation for the presence of APCs using a 4-point scale (grade 1: absent APCs, > or = grade 2: significantly present APCs) was performed, and the relation of the serum levels of these factors to the presence of APCs was assessed. RESULTS: The grade of APCs significantly increased in the Fontan group, but it decreased in the control group. The serum VEGF levels were higher in the Fontan group (280 +/- 174 pg/mL) and the cyanotic group (302 +/- 245 pg/mL) than in the control group (111 +/- 91 pg/mL) (P = .0004), and they were higher in patients with APCs (383 +/- 204 pg/mL) than in those without APCs (115 +/- 65 pg/mL) (P < .0001). There was no significant difference in the serum basic fibroblast growth factor, hepatocyte growth factor, and endostatin levels between the 3 groups. CONCLUSIONS: Aortopulmonary collaterals increase after the Fontan procedure. Serum VEGF levels are associated with the presence of APCs. Vascular endothelial growth factor may play a role in the development of APCs in patients with cyanotic heart disease and after the Fontan procedure.

Is the presence of end-diastolic forward flow specific for restrictive right ventricular physiology in repaired tetralogy of Fallot?

BACKGROUND: End-diastolic forward flow (EDFF) is recognized as restrictive right ventricular physiology (r-RVP), but conflicting results have been reported about effects on the clinical outcome in repaired tetralogy of Fallot (r-TOF). OBJECTIVES: We hypothesized that the EDFF by Doppler was not specific for diagnosing r-RVP. METHODS: Sixty-two consecutive patients aged 15.7±11.6years who underwent cardiac catheterization were studied. Patients were divided according to the presence of EDFF (group 1: EDFF+, group 2: EDFF-) and RV size (group A: small RV, group B: large RV [>150ml/m2]). RESULTS: Group 1 (n=23) had higher a right atrial pressure (RAP), pressure gradient between the RAP and pulmonary diastolic pressure (PDP), and atrial natriuretic peptide (ANP) levels than group 2. Four patients (17.4%) in group 1 and 89.7% of patients in group 2 had a normal RAP range (a wave<10mmHg). There were no differences in the RV volume, ejection fraction (EF), B-type natriuretic peptide levels, and severity of pulmonary regurgitation (PR) between groups 1 and 2. Group A had better RV and LVEF than group B, as well as a smaller LV size. The RAP in subgroup 1A was higher than that of the other 3 subgroups. Subgroup 1B had a similar RAP to group 2, and a lower PDP and a more severe PR than subgroup 1A. CONCLUSIONS: Patients with EDFF are associated with increased ANP levels. The presence of EDFF may not be specific for r-RVP, since it is observed in some TOF patients with low PDP (severe PR) and normal RAP.

Design and Validation of Exoskeleton Actuated by Soft Modules toward Neurorehabilitation-Vision-Based Control for Precise Reaching Motion of Upper Limb.

We demonstrated the design, production, and functional properties of the Exoskeleton Actuated by the Soft Modules (EAsoftM). Integrating the 3D printed exoskeleton with passive joints to compensate gravity and with active joints to rotate the shoulder and elbow joints resulted in ultra-light system that could assist planar reaching motion by using the vision-based control law. The EAsoftM can support the reaching motion with compliance realized by the soft materials and pneumatic actuation. In addition, the vision-based control law has been proposed for the precise control over the target reaching motion within the millimeter scale. Aiming at rehabilitation exercise for individuals, typically soft actuators have been developed for relatively small motions, such as grasping motion, and one of the challenges has been to extend their use for a wider range reaching motion. The proposed EAsoftM presented one possible solution for this challenge by transmitting the torque effectively along the anatomically aligned with a human body exoskeleton. The proposed integrated systems will be an ideal solution for neurorehabilitation where affordable, wearable, and portable systems are required to be customized for individuals with specific motor impairments.

A new dynamic three-dimensional digital color doppler method for quantification of pulmonary regurgitation: validation study in an animal model.

OBJECTIVES: The purpose of the present study was to validate a newly developed three-dimensional (3D) digital color Doppler method for quantifying pulmonary regurgitation (PR), using an animal model of chronic PR. BACKGROUND: Spectral Doppler methods cannot reliably be used to assess pulmonary regurgitation. METHODS: In eight sheep with surgically created PR, 27 different hemodynamic states were studied. Pulmonary and aortic electromagnetic (EM) probes and meters were used to provide reference right ventricular (RV) forward and pulmonary regurgitant stroke volumes. A multiplane transesophageal probe was placed directly on the RV and aimed at the RV outflow tract. Electrocardiogram-gated and rotational 3D scans were performed for acquiring dynamic 3D digital velocity data. After 3D digital Doppler data were transferred to a computer workstation, the RV forward and pulmonary regurgitant flow volumes were obtained by a program that computes the velocity vectors over a spherical surface perpendicular to the direction of scanning. RESULTS: Pulmonary regurgitant volumes and RV forward stroke volumes computed by the 3D method correlated well with those by the EM method (r = 0.95, mean difference = 0.51 +/- 1.89 ml/beat for the pulmonary regurgitant volume; and r = 0.91, mean difference = -0.22 +/- 3.44 ml/beat for the RV stroke volume). As a result of these measurements, the regurgitant fractions derived by the 3D method agreed well with the reference data (r = 0.94, mean difference = 2.06 +/- 6.11%). CONCLUSIONS: The 3D digital color Doppler technique is a promising method for determining pulmonary regurgitant volumes and regurgitant fractions. It should have an important application in clinical settings.

Left ventricular diastolic dysfunction in Ebstein's anomaly.

This study was performed to evaluate left ventricular (LV) diastolic function in patients with Ebstein's anomaly using Doppler echocardiography. We found that LV abnormal relaxation in this anomaly cannot be explained by right ventricular volume overload alone. Furthermore, LV diastolic dysfunction persists even after intracardiac repair.

Growth of stenotic lesions after balloon angioplasty for pulmonary artery stenosis after arterial switch operation.

Little is known about the growth potential of pulmonary stenotic lesions after balloon angioplasty (BA) in patients after the arterial switch operation. The aim of this study was to evaluate the growth potential of pulmonary stenotic lesions after BA and assess the midterm results of BA for pulmonary artery stenosis after the arterial switch operation. Thirty-seven patients who had undergone 52 procedures had repeat catheterization at a median of 43 years (range 1.2 to 9.3 ys) after BA. To adjust growth-related changes in the size of the pulmonary artery, the stenotic diameter was expressed as a percentage of normal (%N). An immediate increase of 63 +/- 45% in the stenotic diameter and a reduction of 51 +/- 33% in the pressure gradient occurred across the stenotic lesions after BA. The right ventricular-aortic systolic pressure ratio decreased from 0.67 +/- 0.24 to 0.51 +/- 0.12 after BA (p <0.0001). Compared with immediate data after BA, there was no significant change in the growth-adjusted diameter of the stenotic lesions (68 +/- 26 %N after BA vs 65 +/- 25 %N at follow-up, p = 0.08), and the pressure gradient (16 +/- 13 mm Hg after BA vs 20 +/- 21 mm Hg at follow-up, p = 0.10). The ventricular-aortic systolic pressure ratio also did not change (0.51 +/- 0.12 after BA vs 0.50 +/- 0.21 at follow-up, p = 0.57). Restenosis occurred in 3 of 26 vessels (12%) after successful BA in which the diameter increased >50% after BA. Our data suggest that pulmonary stenotic lesions after BA develop with age in growing children after the arterial switch operation, and the efficacy of the BA may be long lasting.

A validation study of aortic stroke volume using dynamic 4-dimensional color Doppler: an in vivo study.

OBJECTIVE: To explore the feasibility of directly quantifying transaortic stroke volume with a newly developed dynamic 3-dimensional (3D) color Doppler flow measurement technique, an in vivo experimental study was performed. BACKGROUND: Traditional methods for flow quantification require geometric assumptions about flow area and flow profiles. Accurate quantification of flow across the aortic valve is clinically important as a means of estimating cardiac output. METHODS: Eight open-chest sheep were scanned with apical epicardial placement of a 7 to 4 MHz multiplane transesophageal probe scanning parallel to aortic flow and running on an ATL HDI 5000 system. An electromagnetic flow meter implanted on the ascending aorta was used as reference. Thirty different hemodynamic conditions were studied after steady states were obtained in the animals by administration of blood, angiotensin, and sodium nitroprusside. Electrocardiogram-gated digital color 3D velocity data were acquired for each of the 30 steady states. The aortic stroke volumes were computed by temporal and spatial integration of flow areas and actual velocities across a projected surface perpendicular to the direction of flow, at a level just below the aortic valve. RESULTS: There was close correlation between the 3D color Doppler calculated aortic stroke volumes and the electromagnetic data (r = 0.91, y = 0.96x + 1.01, standard error of the estimate = 2.6 mL/beat). CONCLUSION: Our results showed that dynamic 3D color Doppler measurements obtained in an open-chest animals provide the basis for accurate, geometry-independent quantitative evaluation of the aortic flow. Therefore, 3D digital color Doppler flow computation could potentially represent an important method for noninvasively determining cardiac output in patients.

Quantification of instantaneous flow rate and dynamically changing effective orifice area using a geometry independent three-dimensional digital color Doppler method: An in vitro study mimicking mitral regurgitation.

OBJECTIVE: Our study was intended to test the accuracy of a 3-dimensional (3D) digital color Doppler flow convergence (FC) method for assessing the effective orifice area (EOA) in a new dynamic orifice model mimicking a variety of mitral regurgitation. BACKGROUND: FC surface area methods for detecting EOA have been reported to be useful for quantifying the severity of valvular regurgitation. With our new 3D digital direct FC method, all raw velocity data are available and variable Nyquist limits can be selected for computation of direct FC surface area for computing instantaneous flow rate and temporal change of EOA. METHODS: A 7.0-MHz multiplane transesophageal probe from an ultrasound system (ATL HDI 5000) was linked and controlled by a computer workstation to provide 3D images. Three differently shaped latex orifices (zigzag, arc, and straight slit, each with cutting-edge length of 1 cm) were used to mimic the dynamic orifice of mitral regurgitation. 3D FC surface computation was performed on parallel slices through the 3D data set at aliasing velocities (14-48 cm/s) selected to maximize the regularity and minimize lateral dropout of the visualized 3D FC at 5 points per cardiac cycle. Using continuous wave velocity for each, 3D-calculated EOA was compared with EOA determined by using continuous wave Doppler and the flow rate from a reference ultrasonic flow meter. Simultaneous digital video images were also recorded to define the actual orifice size for 9 stroke volumes (15-55 mL/beat with maximum flow rates 45-182 mL/s). RESULTS: Over the 9 pulsatile flow states and 3 orifices, 3D FC EOAs (0.05-0.63 cm(2)) from different phases of the cardiac cycle in each pump setting correlated well with reference EOA (r = 0.89-0.92, SEE = 0.027-0.055cm(2)) and they also correlated well with digital video images of the actual orifice peak (r = 0.97-0.98, SEE = 0.016-0.019 cm(2)), although they were consistently smaller, as expected by the contraction coefficient. CONCLUSION: The digital 3D FC method can accurately predict flow rate, and, thus, EOA (in conjunction with continuous wave Doppler), because it allows direct FC surface measurement despite temporal variability of FC shape.

Direct quantification of transmitral flow volume with dynamic 3-dimensional digital color Doppler: a validation study in an animal model.

Accurately quantifying transmitral flow volume is clinically important not only as a measure of cardiac output, but also as a value from which to subtract aortic flow, for determining the severity of mitral regurgitation. However, controversy exists over the accuracy of pulsed Doppler for mitral flow quantification because of the complexity of mitral flow geometry and dynamic changes in flow profile and flow area. To explore the feasibility of directly quantifying transmitral flow volume with a newly developed dynamic 3-dimensional digital color Doppler technique, this in vivo experimental study was conducted to validate the method. Eight open chest sheep were imaged with a multiplane transesophageal (TEE) probe placed on the heart for digital 3-dimensional gated acquisition of mitral inflow over a 180-degree acquisition. The digital velocity data were contour detected for flow area after computing the velocity vectors and flow profile perpendicular to a spherical 3-dimensional surface across the mitral annulus. Flow areas and actual velocities were then integrated in time and space and the resulting flow volumes were compared with those obtained by a reference electromagnetic flowmeter on the aorta for 26 steady hemodynamic states. The flow volumes correlated closely to the electromagnetic references (y = 0.87x + 2.49, r = 0.92, SEE = 1.9 Ml per beat). Our study shows that transmitral flow volume can be accurately determined in vivo by this dynamic 3-dimensional digital color Doppler flow quantification method.

Real-time 3-dimensional echocardiography for quantification of the difference in left ventricular versus right ventricular stroke volume in a chronic animal model study: Improved results using C-scans for quantifying aortic regurgitation.

OBJECTIVE: The purpose of our study was to test the applicability of calculating the difference between left ventricular (LV) and right ventricular (RV) stroke volume (SV) for assessing the severity of aortic (Ao) regurgitation (AR) using a real-time 3-dimensional (3D) echocardiographic (RT3DE) imaging system. METHODS: The Ao valve was incised in 5 juvenile sheep, 6 to 10 weeks before the study, to produce AR (mean regurgitant fraction = 0.50). Simultaneous hemodynamic and RT3DE images were obtained on open-chest animals with Ao and pulmonary flows derived by Ao and pulmonary electromagnetic flowmeters balanced against each other. Four stages (baseline, volume loading, sodium nitroprusside, and angiotensin infusion) were used to produce a total of 16 different hemodynamic states. Epicardial scanning was done with a 2.5-MHz probe to sequentially record first the RV and then the LV cavities. Cavity volumes from the 3D echocardiography data were determined from angled sector planes (B-scans) and parallel cutting planes (C-scans, which are planes perpendicular to the direction of the volume interrogation). AR volumes were determined from 3D images by computing and then subtracting RV SVs from LV SVs and then these were compared with electromagnetic flowmeter-derived SV and regurgitant volumes. RESULTS: There was close correlation between RV and LV SVs of the RT3DE and electromagnetic methods (C-scans: LV, r = 0.98, standard error of the estimate [SEE] = 2.62 mL, P =.0001; RV, r = 0.89, SEE = 2.67 mL, P <.0001; and B-scans: LV, r = 0.95, SEE = 3.55 mL, P =.0001; RV, r = 0.77, SEE = 2.78 mL, P =.0003). Because of the small size of the RV in this model, the correlation was closer for C-scans than B-scans for RV SV. AR volume estimation also showed that C-scan (r = 0.93, SEE = 4.23 mL, P <.0001) had closer correlation than B-scan (r = 0.89, SEE = 4.87 mL, P <.0001). However, B-scan-derived AR fraction showed closer correlation than did C-scan (r = 0.82 vs r = 0.85, respectively). CONCLUSION: In this animal model, RT3DE imaging had the ability to reliably quantify both LV (B- and C-scans) and RV SVs and to assess the severity of AR.