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Cardiac cycle
About: Cardiac cycle is a research topic. Over the lifetime, 3290 publications have been published within this topic receiving 96159 citations.
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TL;DR: The angiographic method is nearly similar to the Dodge area-length technique, and is applicable for any phase of the cardiac cycle, and will facilitate comparative analysis of right and left ventricular performance in various forms of heart disease.
135 citations
TL;DR: Maps of the timing of contraction in normal subjects may serve as a reference in detecting mechanical asynchrony due to intraventricular conduction defects or ischemia in healthy persons.
Abstract: Mechanical asynchrony is an important parameter in predicting the response to cardiac resynchronization therapy, but detailed knowledge of cardiac contraction timing in healthy persons is scarce. I...
135 citations
TL;DR: This is the first study to report quantitative 3D assessment of theMitral and aortic valve dynamics from matrix array transesophageal images and describe the mitral-aortic coupling in a beating human heart.
Abstract: Background— Mitral and aortic valves are known to be coupled via fibrous tissue connecting the two annuli. Previous studies evaluating this coupling have been limited to experimental animals using invasive techniques. The new matrix array transesophageal transducer provides high-resolution real-time 3D images of both valves simultaneously. We sought to develop and test a technique for quantitative assessment of mitral and aortic valve dynamics and coupling.
Methods and Results— Matrix array transesophageal (Philips iE33) imaging was performed in 24 patients with normal valves who underwent clinically indicated transesophageal echocardiography. Custom software was used to detect and track the mitral and aortic annuli in 3D space throughout the cardiac cycle, allowing automated measurement of changes in mitral and aortic valve morphology. Mitral annulus surface area and aortic annulus projected area changed reciprocally over time. Mitral annulus surface area was 8.0±2.1 cm2 at end-diastole and decreased to 7.7±2.1 cm2 in systole, reaching its maximum (10.0±2.2 cm2) at mitral valve opening. Aortic annulus projected area was 4.1±1.2 cm2 at end-diastole, then increased during isovolumic contraction reaching its maximum (4.8±1.3 cm2) in the first third of systole and its minimum (3.6±1.0 cm2) during isovolumic relaxation. The angle between the mitral and aortic annuli was maximum (136±13°) at end-diastole and decreased to its minimum value (129±11°) during systole.
Conclusions— This is the first study to report quantitative 3D assessment of the mitral and aortic valve dynamics from matrix array transesophageal images and describe the mitral-aortic coupling in a beating human heart. This ability may have impact on patient evaluation for valvular surgical interventions and prosthesis design.
Received May 19, 2008; accepted November 6, 2008.
# CLINICAL PERSPECTIVE {#article-title-2}
135 citations
TL;DR: Histologically, the main stress-bearing component of the leaflet was made up of thick, dense, collagenous fibers oriented circumferentially, thereby suggesting that the high stress in the Leaflet is shared with the sinus and that continuity of the circumferential stress exists between the leaflets and the sinuses.
134 citations
TL;DR: A dynamic model is described which enables us to capture the same physiological phase or "state" of the anatomy during the cardiac cycle as the instantaneous heart rate varies during the spiral scan, and correlate image quality of different parts of the coronary anatomy with phases at which minimum velocities occur.
Abstract: In this investigation, we describe a quantitative technique to measure coronary motion, which can be correlated with cardiac image quality using multislice computed tomography (MSCT) scanners. MSCT scanners, with subsecond scanning, thin-slice imaging (sub-millimeter) and volume scanning capabilities have paved the way for new clinical applications like noninvasive cardiac imaging. ECG-gated spiral CT using MSCT scanners has made it possible to scan the entire heart in a single breath-hold. The continuous data acquisition makes it possible for multiple phases to be reconstructed from a cardiac cycle. We measure the position and three-dimensional velocities of well-known landmarks along the proximal, mid, and distal regions of the major coronary arteries [left main (LM), left anterior descending (LAD), right coronary artery (RCA), and left circumflex (LCX)] during the cardiac cycle. A dynamic model (called the "delay algorithm") is described which enables us to capture the same physiological phase or "state" of the anatomy during the cardiac cycle as the instantaneous heart rate varies during the spiral scan. The coronary arteries are reconstructed from data obtained during different physiological cardiac phases and we correlate image quality of different parts of the coronary anatomy with phases at which minimum velocities occur. The motion characteristics varied depending on the artery, with the highest motion being observed for RCA. The phases with the lowest mean velocities provided the best visualization. Though more than one phase of relative minimum velocity was observed for each artery, the most consistent image quality was observed during mid-diastole ("diastasis") of the cardiac cycle and was judged to be superior to other reconstructed phases in 92% of the cases. In the process, we also investigated correlation between cardiac arterial states and other measures of motion, such as the left ventricular volume during a cardiac cycle, which earlier has been demonstrated as an example of how anatomic-specific information can be used in a knowledge-based cardiac CT algorithm. Using these estimates in characterizing cardiac motion also provides realistic simulation models for higher heart rates and also in optimizing volume reconstructions for individual segments of the cardiac anatomy.
134 citations