Patient-Specific Inverse Modeling of In Vivo Cardiovascular Mechanics with Medical Image-Derived Kinematics as Input Data: Concepts, Methods, and Applications.

Inverse modeling approaches in cardiovascular medicine are a collection of methodologies that can provide non-invasive patient-specific estimations of tissue properties, mechanical loads, and other mechanics-based risk factors using medical imaging as inputs. Its incorporation into clinical practice has the potential to improve diagnosis and treatment planning with low associated risks and costs. These methods have become available for medical applications mainly due to the continuing development of image-based kinematic techniques, the maturity of the associated theories describing cardiovascular function, and recent progress in computer science, modeling, and simulation engineering. Inverse method applications are multidisciplinary, requiring tailored solutions to the available clinical data, pathology of interest, and available computational resources. Herein, we review biomechanical modeling and simulation principles, methods of solving inverse problems, and techniques for image-based kinematic analysis. In the final section, the major advances in inverse modeling of human cardiovascular mechanics since its early development in the early 2000s are reviewed with emphasis on method-specific descriptions, results, and conclusions. We draw selected studies on healthy and diseased hearts, aortas, and pulmonary arteries achieved through the incorporation of tissue mechanics, hemodynamics, and fluid-structure interaction methods paired with patient-specific data acquired with medical imaging in inverse modeling approaches.

Diagnostic Utility of Three-Dimensional Rotational Angiography in Congenital Cardiac Catheterization.

We evaluated the diagnostic utility of the three modalities of three-dimensional rotational angiography (3DRA): rotational angiography (RA), multiplanar reformat (MPR) and three-dimensional angiographic reconstruction (3D-R) in pediatric cardiac catheterization. The 3DRA studies were classified by anatomy of interest based on our injection protocol: pulmonary arteries (PA), aorta, cavopulmonary connection (CPC), and others. Retrospective review of 3DRA images by two reviewers for each modality was conducted with grading as inferior, similar, or superior in comparison with the diagnostic quality of fixed-plane angiography (FPA). The percentages of grades for each modality were averaged. Weighted kappa statistic was used to evaluate inter-rater reliability. In total, 114 3DRA studies were performed on 87 patients between August 2010 and March 2012. Median age was 2.7 years (1 day-48.4 years) and median weight 12.1 kg (3.6-106.5 kg). For RA: 79.4 % of the studies were of diagnostic quality and 52.2 % were superior; 3D-R: 82 % were of diagnostic quality and 65.8 % were superior; and MPR: 83.5 % were of diagnostic quality and 63 % were superior. Overall 3DRA technologies (RA, 3D-R, MPR) were of diagnostic quality or better in 111/114 (97.4 %) studies and 103/114 (90.4 %) were judged superior. Most common reasons for inferior grading were limited opacification and metallic artifact. In pediatric cardiac catheterization, 3DRA imaging was of diagnostic quality and frequently provided additional clinically relevant data when compared to FPA.

Use of rotational angiography in assessing relationship of the airway to vasculature during cardiac catheterization.

OBJECTIVES: We are the first to describe the use of three-dimensional rotational angiography (3DRA) in creating multiplanar reconstruction (MPR) and volume rendering, in the catheterization suite, of airways at risk for compression by adjacent cardiac structures. BACKGROUND: 3DRA has emerged as a promising tool for improved visualization of cardiac and vascular structures in congenital heart disease. METHODS: This is a retrospective review of all available cases at our institution in which MPR from 3DRA was used to assess airways in relation to surrounding cardiovascular structures. RESULTS: Eight cases were reviewed from January 1, 2011 to November 30, 2013. Seven children had complex biventricular anatomy, including repaired truncus arteriosus, repaired absent pulmonary valve, repaired double outlet right ventricle, and vascular rings. One child had double inlet left ventricle and had undergone a hybrid procedure (stenting of the patent ductus arteriosus and banding of bilateral pulmonary arteries) before the Glenn procedure. Six of these cases involved distortion or stenosis of the pulmonary conduit or branch pulmonary arteries. In all cases, the trachea and the main bronchi were clearly visualized using MPR. Management was affected by the visualization of the airways during the catheterization procedure in seven of eight cases. Four cases had intraprocedural bronchoscopy that confirmed airway findings seen by MPR. In one case, computed tomography confirmed left bronchial compression seen by MPR. CONCLUSIONS: 3DRA can visualize airway anatomy and its relationship to the vasculature accurately. This has significant implications for preinterventional planning, intraprocedural management, as well as postprocedural recovery.

Multimodality 3-dimensional image integration for congenital cardiac catheterization.

Cardiac catheterization procedures for patients with congenital and structural heart disease are becoming more complex. New imaging strategies involving integration of 3-dimensional images from rotational angiography, magnetic resonance imaging (MRI), computerized tomography (CT), and transesophageal echocardiography (TEE) are employed to facilitate these procedures. We discuss the current use of these new 3D imaging technologies and their advantages and challenges when used to guide complex diagnostic and interventional catheterization procedures in patients with congenital heart disease.

Myocardial deformation in the fetal single ventricle.

BACKGROUND: In postnatal life, patients with single ventricle (SV) with morphologic right ventricles have a worse prognosis than those with morphologic left ventricles. The aim of this study was to test the hypotheses that (1) the SV in fetuses with SV has decreased longitudinal strain compared with fetuses with normal cardiac anatomy, and (2) fetuses with SV right ventricular (RV) morphology have decreased strain compared with those with SV left ventricular (LV) morphology. METHODS: Fetal echocardiograms with SV RV and SV LV morphology were retrospectively compiled. Postprocessing analysis of the dominant ventricle was done using syngo Velocity Vector Imaging version 2.0. Peak global longitudinal strain (GLS) and global longitudinal strain rate (GL SR) were generated. Both the right and left ventricles were analyzed in fetuses with normal cardiac anatomy for comparison. RESULTS: Fifty-four fetuses with SV (18 with LV morphology and 36 with RV morphology) were included in the study and compared with 54 controls matched for gestational age. Global longitudinal strain and GL SR were compared between fetuses with SV and normal fetuses and among SV subsets. When all four categories were compared (normal left ventricle, normal right ventricle, SV left ventricle, and SV right ventricle), there was no difference in GLS (P = .49) or in GL SR (P = .32) between any of the categories. CONCLUSIONS: Comparable GLS and GL SR values between fetal SV of LV or RV morphology, as well as normal fetal left and right ventricles, reflect in utero preservation of systolic function of the SV heart.

Cardiovascular disease in children and adolescents with diabetes: where are we, and where are we going?

The increasing prevalence of type 1 and type 2 diabetes mellitus combined with advancement in early detection of cardiovascular disease (CVD) has placed CVD as a significant concern for preventative pediatric medicine. The public health burden of type 2 diabetes is predicted to parallel increasing obesity in children with a projected increase of early CVD in adulthood. In this article, we review practice guidelines for cardiovascular health in children and adolescents with diabetes and data on which they are based. We then focus on imaging modalities that are promising tools to expand our understanding of the cardiovascular risk imposed on youths with diabetes.

First in vivo use of a capacitive micromachined ultrasound transducer array-based imaging and ablation catheter.

OBJECTIVES: The primary objective was to test in vivo for the first time the general operation of a new multifunctional intracardiac echocardiography (ICE) catheter constructed with a microlinear capacitive micromachined ultrasound transducer (ML-CMUT) imaging array. Secondarily, we examined the compatibility of this catheter with electroanatomic mapping (EAM) guidance and also as a radiofrequency ablation (RFA) catheter. Preliminary thermal strain imaging (TSI)-derived temperature data were obtained from within the endocardium simultaneously during RFA to show the feasibility of direct ablation guidance procedures. METHODS: The new 9F forward-looking ICE catheter was constructed with 3 complementary technologies: a CMUT imaging array with a custom electronic array buffer, catheter surface electrodes for EAM guidance, and a special ablation tip, that permits simultaneous TSI and RFA. In vivo imaging studies of 5 anesthetized porcine models with 5 CMUT catheters were performed. RESULTS: The ML-CMUT ICE catheter provided high-resolution real-time wideband 2-dimensional (2D) images at greater than 8 MHz and is capable of both RFA and EAM guidance. Although the 24-element array aperture dimension is only 1.5 mm, the imaging depth of penetration is greater than 30 mm. The specially designed ultrasound-compatible metalized plastic tip allowed simultaneous imaging during ablation and direct acquisition of TSI data for tissue ablation temperatures. Postprocessing analysis showed a first-order correlation between TSI and temperature, permitting early development temperature-time relationships at specific myocardial ablation sites. CONCLUSIONS: Multifunctional forward-looking ML-CMUT ICE catheters, with simultaneous intracardiac guidance, ultrasound imaging, and RFA, may offer a new means to improve interventional ablation procedures.

Multimodality Imaging in Congenital Heart Disease: an Update.

The increasing number of survivors of congenital heart disease (CHD) has been paralleled by advancement of imaging modalities used for the ongoing assessment of these patients. There has been a large body of literature describing new approaches to non-invasive assessment of CHD. We will review new applications of well established as well as novel techniques for the management and understanding of CHD.

Significance of mechanical alterations in single ventricle patients on twisting and circumferential strain as determined by analysis of strain from gradient cine magnetic resonance imaging sequences.

Preliminary speckle-tracking echocardiographic studies show that patients with single ventricles (SVs) have significantly decreased twisting and dyssynchrony of twisting. This could be related to abnormal cardiac looping, which leads to hearts that lack helical fiber patterns. The aim of this study was to analyze gradient cine magnetic resonance imaging (MRI) using Velocity Vector Imaging to assess cardiac mechanics. Subjects were 38 patients (aged 8 to 37 years) with SVs of left ventricular (n = 30) and indeterminate (n = 8) type who underwent cardiac MRI. Controls were 14 normal children and adults. Gradient cine MRI sequences close to the apex were subjected to a Velocity Vector Imaging analysis program adapted for MRI. In the control group, mean circumferential strain was -18.02 +/- 7.31%, mean dispersion of peak circumferential strain was 44.23 +/- 37.14 ms, and average rotation was -7.7 +/- 1.38 degrees . The rotation values were negative, or counterclockwise. In patients with SVs, mean circumferential strain was -8.87 +/- 7.30%, mean dispersion of peak circumferential strain was 181.55 +/- 76.07 ms, and average rotation was -2.6 +/- 1.24 degrees (p <0.001). Mean dispersion of the peak of rotation in the control group was 39.6 +/- 22.8 ms, compared to 166.5 +/- 72.4 ms in patients with SVs. In conclusion, this study showed a dramatic decrease in apical rotation and circumferential strain in the SV group compared to the control group. Strain and rotation mechanics at the apex in patients with SVs showed marked dyssynchrony.

Effect of antibiotic pretreatment on cerebrospinal fluid profiles of children with bacterial meningitis.

OBJECTIVE: The goal of this study was to evaluate the effect of antibiotic administration before lumbar puncture on cerebrospinal fluid profiles in children with bacterial meningitis. METHODS: We reviewed the medical records of all children (1 month to 18 years of age) with bacterial meningitis who presented to 20 pediatric emergency departments between 2001 and 2004. Bacterial meningitis was defined by positive cerebrospinal fluid culture results for a bacterial pathogen or cerebrospinal fluid pleocytosis with positive blood culture and/or cerebrospinal fluid latex agglutination results. Probable bacterial meningitis was defined as positive cerebrospinal fluid Gram stain results with negative results of bacterial cultures of blood and cerebrospinal fluid. Antibiotic pretreatment was defined as any antibiotic administered within 72 hours before the lumbar puncture. RESULTS: We identified 231 patients with bacterial meningitis and another 14 with probable bacterial meningitis. Of those 245 patients, 85 (35%) had received antibiotic pretreatment. After adjustment for patient age, duration and severity of illness at presentation, and bacterial pathogen, longer duration of antibiotic pretreatment was not significantly associated with cerebrospinal fluid white blood cell count, cerebrospinal fluid absolute neutrophil count. However, antibiotic pretreatment was significantly associated with higher cerebrospinal fluid glucose and lower cerebrospinal fluid protein levels. Although these effects became apparent earlier, patients with >or=12 hours of pretreatment, compared with patients who either were not pretreated or were pretreated for <12 hours, had significantly higher median cerebrospinal fluid glucose levels (48 mg/dL vs 29 mg/dL) and lower median cerebrospinal fluid protein levels (121 vs 178 mg/dL). CONCLUSIONS: In patients with bacterial meningitis, antibiotic pretreatment is associated with higher cerebrospinal fluid glucose levels and lower cerebrospinal fluid protein levels, although pretreatment does not modify cerebrospinal fluid white blood cell count or absolute neutrophil count results.

Clinical prediction rule for identifying children with cerebrospinal fluid pleocytosis at very low risk of bacterial meningitis.

CONTEXT: Children with cerebrospinal fluid (CSF) pleocytosis are routinely admitted to the hospital and treated with parenteral antibiotics, although few have bacterial meningitis. We previously developed a clinical prediction rule, the Bacterial Meningitis Score, that classifies patients at very low risk of bacterial meningitis if they lack all of the following criteria: positive CSF Gram stain, CSF absolute neutrophil count (ANC) of at least 1000 cells/microL, CSF protein of at least 80 mg/dL, peripheral blood ANC of at least 10,000 cells/microL, and a history of seizure before or at the time of presentation. OBJECTIVE: To validate the Bacterial Meningitis Score in the era of widespread pneumococcal conjugate vaccination. DESIGN, SETTING, AND PATIENTS: A multicenter, retrospective cohort study conducted in emergency departments of 20 US academic medical centers through the Pediatric Emergency Medicine Collaborative Research Committee of the American Academy of Pediatrics. All children aged 29 days to 19 years who presented at participating emergency departments between January 1, 2001, and June 30, 2004, with CSF pleocytosis (CSF white blood cells > or =10 cells/microL) and who had not received antibiotic treatment before lumbar puncture. MAIN OUTCOME MEASURE: The sensitivity and negative predictive value of the Bacterial Meningitis Score. RESULTS: Among 3295 patients with CSF pleocytosis, 121 (3.7%; 95% confidence interval [CI], 3.1%-4.4%) had bacterial meningitis and 3174 (96.3%; 95% CI, 95.5%-96.9%) had aseptic meningitis. Of the 1714 patients categorized as very low risk for bacterial meningitis by the Bacterial Meningitis Score, only 2 had bacterial meningitis (sensitivity, 98.3%; 95% CI, 94.2%-99.8%; negative predictive value, 99.9%; 95% CI, 99.6%-100%), and both were younger than 2 months old. A total of 2518 patients (80%) with aseptic meningitis were hospitalized. CONCLUSIONS: This large multicenter study validates the Bacterial Meningitis Score prediction rule in the era of conjugate pneumococcal vaccine as an accurate decision support tool. The risk of bacterial meningitis is very low (0.1%) in patients with none of the criteria. The Bacterial Meningitis Score may be helpful to guide clinical decision making for the management of children presenting to emergency departments with CSF pleocytosis.