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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: Unwanted and unexpected changes in aortic annular function secondary to mitral valve repair with an annuloplasty ring due to altered MAC mechanisms are shown.
Abstract: Background The aortic valve and the mitral valve (MV) are coupled via fibrous tissue. Simultaneous dynamic analysis of the two valves' annuli has demonstrated that they have synchronous and reciprocal behavior. Accordingly, the aims of this study were to characterize mitral-aortic coupling (MAC) in three-dimensional space before and after MV repair and to identify the untoward effects of annuloplasty rings on MAC compared with normal valvular function. Methods Real-time three-dimensional transesophageal echocardiography was performed on 28 consecutive patients with degenerative MV disease and severe mitral regurgitation before and after MV repair and in 25 age-matched control subjects. Custom software was used to semiautomatically identify the mitral and aortic annuli throughout the cardiac cycle and to measure parameters describing valvular dynamics. Results Patients with mitral regurgitation before MV repair were characterized by altered morphology and function of the MV but preserved MAC because of the maintained ability of the mitral annulus to change size and position. MV repair together with annuloplasty ring implantation forced the mitral annulus to be smaller and less pulsatile, with decreased displacement ability compared with normal mitral annuli. Because of this alteration in MAC, the “unaffected” aortic annulus became less pulsatile and less mobile. Conclusions This study shows unwanted and unexpected changes in aortic annular function secondary to mitral valve repair with an annuloplasty ring due to altered MAC mechanisms. These changes may alter the dynamic mechanism of the aortic root that facilitates blood ejection, so MAC should be considered and evaluated from diagnosis to treatment in MV disease.

38 citations

Journal ArticleDOI
TL;DR: It is concluded that Emax by this aortic occlusion method is useful for assessment of left ventricular contractility of the in situ dog heart.
Abstract: The purpose of this study was to establish a new method of assessment of the slope (Emax) of the end-systolic pressure-volume line (ESPVL) of the in situ heart. In anesthetized open-chest dogs, an isovolumic contraction was produced by an aortic occlusion after steady-state ejecting contractions in the left ventricle. We plotted ventricular pressure measured with a catheter-tip manometer against time integral of aortic flow measured with an electromagnetic flowmeter of the last ejecting and the first isovolumic contraction, assuming the same end-diastolic volume. ESPVL was drawn from the peak isovolumic pressure-volume point tangential to the left upper corner of the +/- 3.0 (SE) mmHg/ml (n = 9 dogs) in control run and was increased by 59 +/- 19% under isoproterenol and decreased by 47 +/- 9% after propranolol. Emax was little changed by atrial pacing. We conclude that Emax by this aortic occlusion method is useful for assessment of left ventricular contractility of the in situ dog heart.

38 citations

Journal ArticleDOI
TL;DR: An evaluation and a comparison of left ventricular regional wall motion were performed in 32 patients with idiopathic dilated cardiomyopathy and 17 control subjects, using frame by frame video intensity analysis of digitized ventriculograms to evaluate the whole cardiac cycle in short overlapping intervals.
Abstract: An evaluation and a comparison of left ventricular regional wall motion were performed in 32 patients with idiopathic dilated cardiomyopathy, none of whom had coronary artery diameter stenosis exceeding 20% in any major artery, and 17 control subjects, using frame by frame video intensity analysis of digitized ventriculograms. This technique evaluates the whole cardiac cycle in short overlapping intervals and yields information for systolic and diastolic events, without assumptions regarding the position and orientation of the ventricle. Diastolic regional wall motion abnormalities were found in 31 of 32 patients and systolic abnormalities were present in 16 patients. Asynchronous regions most commonly detected during diastole were anteroapical and apical; they were found in 19 of 32 patients. Regional contraction abnormality was observed in the apical and the anteroapical regions in 6 of 16 patients. Dilatation-induced changes in left ventricular shape exaggerate the phenomenon of higher wall stress at the apex of the normal ventricle. Basal wall motion is thus relatively preserved in dilated cardiomyopathy.

38 citations

Journal ArticleDOI
TL;DR: Cardiac output by the indocyanine-green-dilution technique, systemic arterials, right atrial, pulmonary arterial, and ventricular end-diastolic pressures were measured without thoracotomy to evaluat...
Abstract: Cardiac output by the indocyanine-green-dilution technique, systemic arterial, right atrial, pulmonary arterial, and ventricular end-diastolic pressures were measured without thoracotomy to evaluat...

38 citations

Journal ArticleDOI
TL;DR: To measure cardiac blood flow patterns and ventricular wall velocities through the cardiac cycle in anesthetized Wistar Kyoto (WKY) rats, a high-performance liquid chromatography method is used.
Abstract: Purpose To measure cardiac blood flow patterns and ventricular wall velocities through the cardiac cycle in anesthetized Wistar Kyoto (WKY) rats. Materials and Methods A gradient-echo cine pulse sequence incorporating pulsed field gradients (PFGs) provided phase contrast (PC) motion encoding. We achieved a range of velocity sensitivity that was sufficient to measure simultaneously the large flow velocities within the cardiac chambers and aortic outflow tract (up to 70 cm s−1 during systole), and the comparatively small velocities of the cardiac wall (0–3 cm s−1). A scheme of sparsely sampling q-space combined with a probability-based method of velocity calculation permitted such measurements along three orthogonal axes, and yielded velocity vector maps in all four chambers of the heart and the aorta, in both longitudinal and transverse sections, for up to 12 time-points in the cardiac cycle. Results Left ventricular systole was associated with a symmetrical laminar flow pattern along the cardiac axis, with no appearance of turbulence. In contrast, blood showed a swirling motion within the right ventricle (RV) in the region of the pulmonary outflow tract. During left ventricular diastole a plume of blood entered the left ventricle (LV) from the left atrium. The ventricular flow patterns could also be correlated with measurements of left ventricular wall motion. The greatest velocities of the ventricular walls occurred in the transverse cardiac plane and were maximal during diastolic refilling. The cardiac wall motion in the longitudinal axis demonstrated a caudal-apical movement that may also contribute to diastolic refilling. Conclusion The successful measurements of blood and myocardial velocity during normal myocardial function may be extended to quantify pathological cardiac changes in animal models of human cardiac disease.

38 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202377
2022178
202169
202068
201979
201876