Cardiac cycle

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

Measurement of cardiac cycle length and pressure metrics from pulmonary arterial pressure

Abstract: Various techniques for measuring cardiac cycle length and pressure metrics based on pulmonary artery pressures are described. One example method described includes identifying a point within a derivative signal of a cardiovascular pressure signal without reference to electrical activity of a heart, initiating a time window from the identified point in the derivative signal, identifying a point within the cardiovascular signal within the time window, and determining at least one of a systolic pressure or diastolic pressure based on the identified point.

Influence of the timing of atrial systole on mitral valve closure and on the first heart sound in man.

Abstract: Simultaneous recordings of electrocardiogram, phonocardiogram, indirect carotid pulse and pulsed ultrasound cardiogram of the anterior mitral leaflet were obtained in patients with heart block. In patients with compensated heart failure and heart block, the timing of mitral valve closure was a function of the timing of atrial systole for all beats with an effective diastolic P wave and a P-R interval greater than 0.2 second. Once closed, the mitral valve stayed closed through the remainder of diastole. In 1 patient with acute left heart failure, diastolic P waves did not result in mitral valve closure. The amplitude of the first heart sound was closely related to the timing of mitral valve closure. The mitral valve closure in diastole was silent, and the subsequent first sound was small. When the valve closed in early systole, the amplitude of the first sound was related to the rate and amplitude of the valve closure movement. The timing of mitral valve closure in relation to the left ventricular pressure pulse may be the important determinant of production of the first sound.

Accelerometer-Based method for extracting respiratory and cardiac gating information for dual gating during nuclear medicine imaging

Abstract: Both respiratory and cardiac motions reduce the quality and consistency of medical imaging specifically in nuclear medicine imaging. Motion artifacts can be eliminated by gating the image acquisition based on the respiratory phase and cardiac contractions throughout the medical imaging procedure. Electrocardiography (ECG), 3-axis accelerometer, and respiration belt data were processed and analyzed from ten healthy volunteers. Seismocardiography (SCG) is a noninvasive accelerometer-based method that measures accelerations caused by respiration and myocardial movements. This study was conducted to investigate the feasibility of the accelerometer-based method in dual gating technique. The SCG provides accelerometer-derived respiratory (ADR) data and accurate information about quiescent phases within the cardiac cycle. The correct information about the status of ventricles and atria helps us to create an improved estimate for quiescent phases within a cardiac cycle. The correlation of ADR signals with the reference respiration belt was investigated using Pearson correlation. High linear correlation was observed between accelerometer-based measurement and reference measurement methods (ECG and Respiration belt). Above all, due to the simplicity of the proposed method, the technique has high potential to be applied in dual gating in clinical cardiac positron emission tomography (PET) to obtain motion-free images in the future.

Relationship of phasic left atrial volume and emptying function to left ventricular filling pressure: a cardiovascular magnetic resonance study

Abstract: Background Left atrial volume (LAV) and emptying fraction (LAEF) are phasic during cardiac cycle. Their relationships to left ventricular end diastolic pressure (LVEDP) have not been fully defined.

Pulsatile blood velocity in human arteries displayed by magnetic resonance imaging.

Abstract: The authors describe a new method for magnetic resonance (MR) imaging of flowing protons which can illustrate relative blood velocity in the arteries supplying the brain. The magnetic gradient pulse sequence was synchronized to the cardiac cycle at 100-msec. increments to track pulsatile blood flow perpendicular to the image plane. The magnitude of the signal increased with the velocity of blood in major arteries flowing in the direction of the spatially offset refocusing plane. The blood velocity in the vertebral and internal carotid arteries varied as a function of the phase of the cardiac cycle, and the velocity profiles across the vascular lumina were compatible with laminar flow.