Cardiac cycle

About: Cardiac cycle is a research topic. Over the lifetime, 3290 publications have been published within this topic receiving 96159 citations.

Three-dimensional analysis of interventricular septal curvature from cardiac magnetic resonance images for the evaluation of patients with pulmonary hypertension

Abstract: Although abnormal septal motion is a well-known sign of increased pulmonary arterial pressures, it is not routinely used to quantify the severity of pulmonary hypertension (PH). This determination relies on invasive measurements or Doppler echocardiographic estimation of right ventricular (RV) pressures, which is not always feasible or accurate in patients with PH. We hypothesized that dynamic 3D analysis of septal curvature from cardiac magnetic resonance (CMR) images may reveal differences between patients with different degrees of PH. Forty-four patients (14 controls; 30 PH patients who underwent right heart catheterization) were studied using CMR and echocardiography. CMR imaging was performed using Philips 1.5T scanner with a phased-array cardiac coil, in a retrospectively gated steady-state free precession cine mode at 30 frames per cardiac cycle. Patients were divided into 3 subgroups according to pulmonary arterial pressure. CMR images were used to reconstruct dynamic 3D left ventricular endocardial surfaces, which were analyzed to calculate septal curvature throughout the cardiac cycle. 3D curvature analysis was feasible in 88% patients. Septal curvature showed different temporal patterns in different groups. Curvature values progressively decreased with increasing severity of PH, and correlated well with invasive pressures (r-values 0.78–0.79), pulmonary vascular resistance (r = 0.83) and Doppler-derived RV peak-systolic pressure (r = 0.75). 3D analysis of septal curvature from CMR images may become a useful component in the CMR examination in patients with known or suspected PH.

Variable open-end wave reflection in the pulmonary arteries of anesthetized sheep

Abstract: The aim of this study was to re-evaluate wave reflection in the healthy pulmonary arteries of sheep utilizing the time-domain-based method of wave intensity analysis. A thorough understanding of patterns of wave reflection during health and disease may provide future sensitive markers of early pulmonary vascular disease. Wave intensity was calculated from the simultaneous acquisition of proximal pulmonary arterial pressure and velocity in 12 anesthetized open-chest sheep. Normal pulmonary arterial wave speed was 2.1 ± 0.3 m s−1. The incident forward compression wave generated by right ventricular systole was reflected in an open-end manner as a backward expansion wave from a site 3 cm downstream, corresponding to the main pulmonary bifurcation, and in a closed-end manner as a backward compression wave from a site 21 cm downstream, corresponding to the pulmonary microcirculation. The proximal open-end reflection site was not present throughout the entire cardiac cycle. Wave reflection was minimal with only 1% of the incident forward compression wave energy reflected as a backward expansion wave and 2% as a backward compression wave. The normal pulmonary artery in open-chest sheep is characterized by variable proximal open-end reflection from the main pulmonary bifurcation and fixed closed-end reflection from the microcirculation, generating backward-travelling waves of minimal intensity.

Development of aortic and mitral valve continuity in the human embryonic heart.

Abstract: The anatomic relationship of the aortic and mitral valves is a useful landmark in assessing congenital heart malformations. The atrioventricular and semilunar valve regions originate in widely separated parts of the early embryonic heart tube, and the process by which the normal fibrous continuity between the aortic and mitral valves is acquired has not been clearly defined. The development of the aortic and mitral valve relationship was studied in normal human embryos in the Carnegie Embryological Collection, and specimens of Carnegie stages 13, 15, 17, 19, and 23, prepared as serial histologic sections cut in the sagittal plane, were selected for reconstruction. In stage 13, the atrioventricular valve area is separated from the semilunar valve area by the large bend between the atrioventricular and outflow-tract components of the single lumen heart tube created by the left interventricular sulcus. In stages 15 and 17, the aortic valve rotates into a position near the atrioventricular valves with development of four chambers and a double circulation. In stage 19, there is fusion of aortic and mitral endocardial cushion material along the endocardial surface of the interventricular flange, and this relationship is maintained in subsequent stages. Determination of three-dimensional Cartesian coordinates of the midpoints of valve positions shows that, while there is growth of intervalvular distances up to stage 17, the aortic to mitral distance is essentially unchanged thereafter. During the period studied, the left ventricle increases in length over threefold. The relative lack of growth in the saddle-shaped fold between the atrioventricular and outflow tract components of the heart, contrasting with the rapid growth of the outwardly convex components of most of the atrial and ventricular walls, may be attributed to the different mechanical properties of the two configurations. It is postulated that the pathogenesis of congenital heart malformations, which characteristically have failure of development of aortic and mitral valve continuity, may involve abnormalities of rotation of the aortic region or malpositioning of the fold in the heart tube.

Contraction status assessment

Abstract: An implantable medical device receives at least one sensor signal representing inter-movement between a basal region of a heart ventricle and a ventricle apex during at least a portion of a systolic phase of a cardiac cycle. A parameter processor calculates a contraction status parameter value based on the at least one sensor signal. This contraction status parameter value represents an elongation of the ventricle following onset of ventricular activation during a cardiac cycle. The contraction status parameter value is stored in a memory as a diagnostic parameter representing a current contraction status of a subject's heart.

Movement of the aortic annulus.

Abstract: Movement of the human aortic annulus is recorded and described in ten aortic root cine-angiograms in the lateral or left anterior oblique projections. Diametrically opposed points at valve cusp attachments were plotted through a complete cardiac cycle. The mechanism of annular movement is discussed.