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Cardiovascular Disease
Published in John S. Axford, Chris A. O'Callaghan, Medicine for Finals and Beyond, 2023
There are different types of systolic murmur: Pansystolic murmur: This is a sustained murmur throughout systole up to and including the aortic component of the second heart sound. It is a feature of MR, tricuspid regurgitation and ventricular septal defect (VSD).Late systolic murmur: This is a crescendo murmur in the latter part of systole. It is often preceded by a click and indicates MVP with regurgitation.Ejection systolic murmur: This is a crescendo/decrescendo systolic murmur caused by stenosis of the aortic or pulmonary valves.Innocent (benign) systolic murmur: Particularly common in children, this characteristically occurs early in systole. There is no underlying structural heart defect and it is of no importance.
Venous flow is pulsatile
Published in Dinker B. Rai, Mechanical Function of the Atrial Diastole, 2022
During ventricular systole there is a surge of blood into the arterial system which increases the flow and volume of the blood in the arteries. During the diastole of the ventricle the arteries do not completely collapse owing to the compliance in the wall of the artery. This helps the circulation in two ways. First if the arteries were to completely collapse during diastole then there would have been cessation of the flow of blood to the arteries. This would have resulted in the doubling of the workload on the consecutive ventricular systole. Second, compliance of the artery keeps the blood in motion during diastole, permitting the consecutive ventricular systole to take over the flow of blood in the already dilated arteries and resulting in a decrease of the workload of the ventricle by half. This observation of ventricular systole with active contraction of the muscles pushing the blood into the arteries and refilling itself during diastole without any interference in the flow of blood in the arteries has resulted in the popular inferences that systole is the only active function in the cardiac cycle of the heart and diastole, which is the filling phase, is the resting phase of the heart.
A Review of Automatic Cardiac Segmentation using Deep Learning and Deformable Models
Published in Kayvan Najarian, Delaram Kahrobaei, Enrique Domínguez, Reza Soroushmehr, Artificial Intelligence in Healthcare and Medicine, 2022
Behnam Rahmatikaregar, Shahram Shirani, Zahra Keshavarz-Motamed
The cardiac cycle is defined as a sequence of alternating contractions and relaxations of the atria and ventricles in order to pump blood throughout the body. This cycle starts at the beginning of one heartbeat and ends at the start of the next. Each cardiac cycle has a diastolic phase (also called diastole) and a systolic phase (also called systole). Diastole occurs when the heart muscles relax, and the chambers are able to fill with blood. Systole occurs when the ventricles contract, pushing blood out of the right and left ventricles into the lungs and the rest of the body, respectively. Since manual delineation of ventricle contours in all cardiac phases is not possible, physicians focus only on end-diastole and end-systole phases for assessment of the cardiovascular system.
Physiological characterization of an arginine vasopressin rat model of preeclampsia
Published in Systems Biology in Reproductive Medicine, 2022
Sapna Ramdin, Thajasvarie Naicker, Virushka Pillay, Sanil D. Singh, Sooraj Baijnath, Blessing N Mkhwanazi, Nalini Govender
Based on the pilot study outcomes, an AVP dose of 150 ng/h was chosen since it produced the most significant changes in blood pressure and proteinuria compared to the lower doses tested. The ALZET mini osmotic pumps were subcutaneously implanted on GD 1 and remained implanted until sacrifice (GD 18) in all study groups. Saline and AVP (150 ng/h) were subcutaneously delivered throughout gestation, to the control and experimental groups respectively and pumps were removed at sacrifice (GD 18). Systolic and diastolic blood pressure was measured on GD 8, 14, and 18 using the MRBP tail-cuff BP monitor (IITC Life Sciences Inc., USA), by placing animals in a suitably sized restrainer. Normal blood pressure was defined as systolic ≤120 mmHg and diastolic ≤80 mmHg. Hypertension in rats was defined as systolic ≥140 mmHg and diastolic ≥90 mmHg (Brown et al. 2018). Animals were housed in metabolic cages (Techniplast, Italy) on GD 8, 14, and 18, for the measurement of water intake and urinary output; and collection of 24 h urine samples. Urinary protein content was measured using the M-TP Microprotein Kit (Beckman Coulter, CA, USA) and read using the SYNCHRON LX® System (Beckman Coulter, CA, USA). Animals were then euthanized on GD 18, via isoflurane overdose (Safeline Pharmaceuticals, South Africa). Blood samples were collected via cardiac puncture and centrifuged for 15 min at 3500 rpm at 4°C. The number and weight of placentae and pups were recorded. Biochemical and hematological analysis was carried out by a pathology laboratory using rodent reference ranges.
Complications associated with myocardial bridging in four children without underlying cardiac disease: a case series
Published in Paediatrics and International Child Health, 2021
Federica Brancato, Donato Rigante, Marco Piastra, Alessandro Gambacorta, Claudia Aurilia, Gabriella De Rosa
One of the most important triggers of symptomatic MB is intense physical activity which through tachycardia and increased contractility can facilitate myocardial ischaemia. During tachycardia, systole occupies a greater proportion of the cardiac cycle because of shortening of the diastolic filling period. Other pathophysiological factors that might reveal or exacerbate MB are age, left ventricular hypertrophy and coronary atherosclerosis, since all of these may worsen the supply-demand mismatch imposed by the bridge, reducing the coronary reserve [15]. Symptomatic patients may also present with clinical manifestations of myocardial ischaemia such as acute coronary syndrome, coronary spasm, exercise-induced dysrhythmias, myocardial stunning, transient ventricular dysfunction and syncope [15]. Only patients with symptomatic MB or those with objective signs of ischaemia require treatment. In most cases, beta-blockers, ivabradine and calcium channel blockers are effective in reducing symptoms [15]. In adults, myotomy, coronary artery by-pass surgery and stenting may be used to improve symptoms in patients with MB who are refractory to medical therapy [2,20,22,23]. MB is diagnosed by coronary or CT angiography, but it is sometimes established intra-operatively or at post-mortem examination. Another relevant diagnostic test is the stress ECG: the main objective of stress testing for myocardial ischaemia is to demonstrate the mismatch between myocardial oxygen demand and myocardial perfusion [22].
Right Ventricular-Pulmonary Arterial Coupling and Outcomes in Heart Failure and Valvular Heart Disease
Published in Structural Heart, 2021
Bahira Shahim, Rebecca T. Hahn
Pressure-volume loop analysis is a means of measuring load-independent contractility. The pressure-volume loop for the RV is ellipsoid or trapezoid shape (Figure 1) possibly as a result of the very compliant pulmonary tree making isovolumic contraction less distinct, as well as the prolonged ejection phase extending beyond the end of systole,21–23 consistent with the late contraction of the infundibulum previously described. The non-rectangular shape of a typical RV loop can make it difficult to identify the end-systolic pressure versus end-systolic volume point. Acquisition of multiple pressure-volume loops obtained while varying volume will determine the slope of the end-systolic pressure versus end-systolic volume points known as the end-systolic elastance (Ees) and is considered a load-independent measure of ventricular contractility.