Assessment of RV stiffness and relaxation

Right ventricle (RV) has frequently been described as the forgotten ventricle in the circulation. However, its importance in various cardiac diseases is now unquestioned. This recognition has led to improved risk stratification and development of algorithms for intervention, which incorporate measurements of RV function as key components of the assessment of many conditions. The diastolic function plays an important role in determining ventricular filling and stroke volume. Abnormal left ventricular (LV) diastolic function has been recognized in many cardiovascular diseases and is associated with worse outcomes, including total mortality and hospitalizations due to heart failure. In this review, we define what global RV diastolic function is, and how to measure it. This article indicates the validation of kinematic model parameters for assessing RV diastolic function

PA disorder and RV failure

Potassium channels play diverse roles in regulating the behavior of pulmonary artery smooth muscle cells. The discovery of KCNK３（TASK１）as a new predisposing gene for pulmonary arterial hypertension（PAH）led to an update in the Nice Classification regarding the genetic origin of PAH. Decreased current via KCNA５（Kv１．５）plays a key role in determining pulmonary arterial tone and vascular remodeling. The transformation of smooth muscle cells causes ion channel switching, such as the loss of BKca（Kca１．１）and the gain of IKca（Kca３．１）, in immature proliferative smooth muscle cells and also induces cell migration, proliferation, and apoptosis resistance. We propose OCT as a useful tool in diagnosing pulmonary artery hypertension and may provide helpful information for the pulmonary arterial remodeling process, severity, therapeutic strategy, and prognosis in congenital heart disease

コドモ ノ シンゾウ オ MDCT デ ミル

Multidetector-row CT（MDCT）scanners are a widely available, accurate, and noninvasivetechnique for the diagnosis of cardiovascular disorders. In the present review, we showed theclinical application for the diagnosis of congenital heart disease. Our study demonstrated thefeasibility of MDCT in assessing pulmonary artery size and morphology. Virtual endoscopy usingMDCT enables evaluation of the inner space of the vessels. Furthermore, MDCT was useful forthe evaluation of prosthetic graft calcificatio

The Action of Smooth Muscle Cell Potassium Channels in the Pathology of Pulmonary Arterial Hypertension

Many different types of potassium channels with various functions exist in pulmonary artery smooth muscle cells, contributing to many physiological actions and pathological conditions. The deep involvement of these channels in the onset and exacerbation of pulmonary arterial hypertension (PAH) also continues to be revealed. In 2013, KCNK3 (TASK1), which encodes a type of two-pore domain potassium channel, was shown to be a predisposing gene for PAH by genetic mutation, and it was added to the PAH classification at the Fifth World Symposium on Pulmonary Hypertension (Nice International Conference). Decreased expression and inhibited activity of voltage-gated potassium channels, particularly KCNA5 (Kv1.5), are also seen in PAH, regardless of the cause, and facilitation of pulmonary arterial contraction and vascular remodeling has been shown. The calcium-activated potassium channels seen in smooth muscle cells also change from BKca (Kca1.1) to IKca (Kca3.1) predominance in PAH due to transformation, and have effects including the facilitation of smooth muscle cell migration, enhancement of proliferation, and inhibition of apoptosis. Elucidation of these roles for potassium channels in pulmonary vasoconstriction and remodeling may help bring new therapeutic strategies into view

OCT for observation of vasa vasorum

Background Hypoxia and low pulmonary arterial (PA) blood flow stimulate the development of systemic-to-pulmonary collateral blood vessels, which can be an adverse factor when performing the Fontan operation. The aim of this study was to use optical coherence tomography (OCT) to elucidate the morphological changes in PA vasculature after creation of a bidirectional cavopulmonary connection (BCPC) in children. Methods This prospective study evaluated PA wall thickness and development of PA vasa vasorum (VV) in the distal PA of eight patients (BCPC group, 1.3 ± 0.3 years) and 20 age-matched children with normal pulmonary artery hemodynamics and morphology (Control group, 1.4 ± 0.3 years). VV development was defined by the VV area ratio, defined as the VV area divided by the adventitial area in cross-sectional images. Results There was no significant difference in PA wall thickness between the BCPC and control groups (0.12 ± 0.03 mm vs. 0.12 ± 0.02 mm, respectively). The VV area ratio was significantly greater in the BCPC group than in the Control group (14.5 ± 3.5% vs. 5.3 ± 1.6%, respectively; p<0.0001). Conclusion OCT is a promising new tool for evaluating PA pathology, including the development of VV in patients after BCPC

RV Stiffness and Relaxation in PAH

We hypothesized that the kinematic model-based parameters obtained from the transtricuspid E-wave would be useful for evaluating RV diastolic property in pediatric pulmonary arterial hypertension (PAH) patients. The model was parametrized by stiffness/elastic recoil k, relaxation/damping c, and load x. These parameters were determined as the solution of m⋅d2x/dt2 + c⋅dx/dt + kx = 0, which is based on the theory that the E-wave contour is determined by the interplay of stiffness/restoring force, damping/relaxation force, and load. The PAH group had a significantly higher k and c versus the control group (182.5 ± 72.4 g/s2 vs. 135.7 ± 49.5 g/s2, p = 0.0232 and 21.9 ± 6.5 g/s vs. 10.6 ± 5.2 g/s, p <0.0001, respectively). These results show that RV has a higher stiffness/elastic recoil and inferior cross-bridge relaxation in the PAH group. Present findings indicate the feasibility and utility of kinematic model parameters for assessing RV diastolic function

A novel index equivalent to the myocardial performance index for right ventricular functional assessment in children and adolescent patients

The aims of the present study were to develop and check the utility and feasibility of a novel right ventricular (RV) functional index (RV angular velocity; RVω, s−1) derived from the angular velocity in harmonic oscillator kinematics obtained from the RV pressure waveform. We hypothesized that RVω reflects the myocardial performance index (MPI), which represents global RV function. A total of 132 consecutive patients, ranging in age from 3 months to 34 years with various cardiac diseases were included in this prospective study. RVω was defined as the difference between the peak derivative of pressure (dP/dt_max − dP/dt_min) divided by the difference between the maximum and minimum pressure (Pmax – Pmin). RVω showed significant negative correlations with the pulsed-wave Dopplerderived myocardial performance index (PWD-MPI) and the tissue Doppler imaging-derived MPI (TDI-MPI) (r = −0.52 and −0.51, respectively; both p < 0.0001). RVω also showed significant positive correlations with RV fractional area change (RVFAC) and RV ejection fraction (RVEF) (r = 0.41 and 0.39, respectively; both p < 0.0001), as well as a significant negative correlation with tricuspid E/e′ (r = −0.19, p = 0.0283). The clinical feasibility and utility of RVω for assessing global RV performance, incorporating both systolic and diastolic function, were demonstrated

IVA for RV function analysis in TOF

Assessment of right ventricular (RV) function is quite important in patients with surgically corrected tetralogy of Fallot (TOF). However, quantitative assessment of RV function remains challenging, mainly because of the complex RV geometry. This prospective study investigated isovolumic acceleration (IVA), a parameter of myocardial systolic function not influenced by either preload or afterload, using tissue Doppler imaging. We evaluated IVA measured on pulmonary annulus (PA-IVA) and tricuspid annulus (TA-IVA), because we considered that PA-IVA and TA-IVA correspond with systolic function of the RV outflow tract (RVOT) and RV basal function, respectively. Thirty-nine patients with surgically repaired TOF (TOF group) and 40 age-matched healthy children (control group) were enrolled in this study. No significant difference was seen between TA-IVA (2.5 ± 0.8 m/s2) and PA-IVA (2.4 ± 0.8 m/s2) in the control group. In the TOF group, PA-IVA (1.0 ± 0.5 m/s2) was significantly lower than TA-IVA (1.3 ± 0.6 m/s2, p < 0.05). Both TA-IVA and PA-IVA were significantly lower in the TOF group than in the control group (p < 0.05 each). We concluded that PA-IVA offers a useful index to assess RVOT function in TOF patients

Noninvasive assessment of pulmonary arterial capacitance by pulmonary annular motion velocity in children with ventricular septal defect

Background: We hypothesized that longitudinal pulmonary arterial deformation during the cardiac cycle reflects pulmonary arterial capacitance. To examine this hypothesis, we assessed whether tissue Doppler-derived pulmonary annular motion could serve as a novel way to evaluate pulmonary arterial capacitance in pediatric patients with ventricular septal defect (VSD). Methods: In this prospective study, pulmonary annular velocity was measured in children (age, 6 months–5 years) with a preoperative VSD (VSD group, n = 35) and age-matched healthy children (Control group, n = 23). Pulmonary artery capacitance was calculated by two methods. Systolic pulmonary arterial capacitance (sPAC) was expressed as the stroke volume/pulmonary arterial pulse pressure. Diastolic pulmonary arterial capacitance (dPAC) was determined according to a two-element windkessel model of the pulmonary arterial diastolic pressure profile. Results: Pulmonary annular velocity waveforms comprised systolic bimodal (s1′ and s2′) and diastolic e’ and a’ waves in all participants. The peak velocities of s1′, s2′, and e’ were significantly lower in the VSD group than in the Control group. On multiple regression analysis, sPAC was an independent variable affecting the peak velocities of the s1′, s2′, and e’ waves (β = 0.41, 0.62, and 0.35, respectively). The dPAC affected the s1′ wave peak velocity (β = 0. 34). The time durations of the s1′ and e’ waves were independently determined by the sPAC (β = 0.49 and 0.27). Conclusion: Pulmonary annular motion velocity evaluated using tissue Doppler is a promising method of assessing pulmonary arterial capacitance in children with VSD