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Diastole
Diastole ( ) is the relaxed phase of the cardiac cycle when the chambers of the heart are refilling with blood. The contrasting phase is systole when the heart chambers are contracting. Atrial diastole is the relaxing of the atria, and ventricular diastole the relaxing of the ventricles. The term originates from the Greek word (''diastolē''), meaning "dilation", from (''diá'', "apart") + (''stéllein'', "to send"). Role in cardiac cycle A typical heart rate is 75 beats per minute (bpm), which means that the cardiac cycle that produces one heartbeat, lasts for less than one second. The cycle requires 0.3 sec in ventricular systole (contraction)—pumping blood to all body systems from the two ventricles; and 0.5 sec in diastole (dilation), re-filling the four chambers of the heart, for a total of 0.8 sec to complete the cycle. Early ventricular diastole During early ventricular diastole, pressure in the two ventricles begins to drop from the peak reached during systole ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heart Diasystole
The heart is a muscular Organ (biology), organ found in humans and other animals. This organ pumps blood through the blood vessels. The heart and blood vessels together make the circulatory system. The pumped blood carries oxygen and nutrients to the tissue, while carrying metabolic waste such as carbon dioxide to the lungs. In humans, the heart is approximately the size of a closed fist and is located between the lungs, in the middle compartment of the thorax, chest, called the mediastinum. In humans, the heart is divided into four chambers: upper left and right Atrium (heart), atria and lower left and right Ventricle (heart), ventricles. Commonly, the right atrium and ventricle are referred together as the right heart and their left counterparts as the left heart. In a healthy heart, blood flows one way through the heart due to heart valves, which prevent cardiac regurgitation, backflow. The heart is enclosed in a protective sac, the pericardium, which also contains a sma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Millimetre Of Mercury
A millimetre of mercury is a manometric unit of pressure, formerly defined as the extra pressure generated by a column of mercury one millimetre high. Currently, it is defined as exactly , or approximately 1 torr = atmosphere = pascals.Council Directive 80/181/EEC of 20 December 1979 on the approximation of the laws of the Member States relating to units of measurement and on the repeal of Directive 71/354/EEC of the It is denoted mmHg or mm Hg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
End Diastolic Volume
In cardiovascular physiology, end-diastolic volume (EDV) is the volume of blood in the right or left ventricle at end of filling in diastole which is amount of blood present in ventricle at the end of diastole. Because greater EDVs cause greater distention of the ventricle, ''EDV'' is often used synonymously with '' preload'', which refers to the length of the sarcomeres in cardiac muscle prior to contraction (systole). An increase in EDV increases the preload on the heart and, through the Frank-Starling mechanism of the heart, increases the amount of blood ejected from the ventricle during systole (stroke volume). __TOC__ Sample values The right ventricular end-diastolic volume (RVEDV) ranges between 100 and 160 mL. The right ventricular end-diastolic volume index (RVEDVI) is calculated by RVEDV/ BSA and ranges between 60 and 100 mL/m2. See also * End-systolic volume * Stroke volume In cardiovascular physiology, stroke volume (SV) is the volume of blood pumped from the ventr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diastolic Function
In clinical cardiology the term "diastolic function" is most commonly referred as how the heart fills. Parallel to "diastolic function", the term " systolic function" is usually referenced in terms of the left ventricular ejection fraction (LVEF), which is the ratio of stroke volume and end-diastolic volume. Due to the epidemic of heart failure, particularly the cases determined as diastolic heart failure, it is increasingly urgent and crucial to understand the meaning of “diastolic function”. Unlike "systolic function", which can be simply evaluated by LVEF, there are no established dimensionless parameters for "diastolic function" assessment. Hence to further study "diastolic function" the complicated and speculative physiology must be taken into consideration. How the heart works during its filling period still has many misconceptions remaining. To better understand diastolic function, it is crucial to realize that the left ventricle is a mechanical suction pump at, and for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diastolic Heart Failure
Heart failure with preserved ejection fraction (HFpEF) is a form of heart failure in which the ejection fraction – the percentage of the volume of blood ejected from the left ventricle with each heartbeat divided by the volume of blood when the left ventricle is maximally filled – is normal, defined as greater than 50%; this may be measured by echocardiography or cardiac catheterization. Approximately half of people with heart failure have preserved ejection fraction, while the other half have a reduction in ejection fraction, called heart failure with reduced ejection fraction (HFrEF). Risk factors for HFpEF include hypertension, hyperlipidemia, diabetes, smoking, and obstructive sleep apnea. Those with HFpEF have a higher prevalence of obesity, type 2 diabetes, hypertension, atrial fibrillation and chronic kidney disease than those with heart failure with reduced ejection fraction. The prevalence of HFpEF is expected to increase as more people develop obesity and other medica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Natriuresis
Natriuresis is the process of sodium excretion in the urine through the action of the kidneys. It is promoted by Brain natriuretic peptide, ventricular and atrial natriuretic peptides as well as calcitonin, and inhibited by chemicals such as aldosterone. Natriuresis lowers the concentration of sodium in the blood and also tends to lower blood volume because osmosis, osmotic forces drag water out of the body's systemic circulation, blood circulation and into the urine along with the sodium. Many diuretic medications, drugs take advantage of this mechanism to treat medical conditions like hypernatremia and hypertension, which involve excess blood volume. Excess natriuresis can be caused by: *Medullary cystic disease *Bartter syndrome *Diuretic phase of acute tubular necrosis *Some diuretics *Primary renal diseases *Congenital adrenal hyperplasia *Syndrome of inappropriate antidiuretic hormone hypersecretion Endogenous natriuretic hormones include: * Atrial natriuretic peptide * Brain ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neurohormone
A neurohormone is any hormone produced and released by neuroendocrine cells (also called neurosecretory cells) into the blood. By definition of being hormones, they are secreted into the circulation for systemic effect, but they can also have a role of neurotransmitter or other roles such as autocrine (self) or paracrine (local) messenger. The hypothalamus releasing hormones are neurohypophysial hormones in specialized hypothalamic neurons which extend to the median eminence and posterior pituitary. The adrenal medulla produces adrenomedullary hormones in chromaffin cells, cells which are very similar in structure to post-synaptic sympathetic neurons, even though they are not neurons they are derivatives of the neural crest. Enterochromaffin and enterochromaffin-like cells, both being enteroendocrine cells, are also considered neuroendocrine cells due to their structural and functional similarity to chromaffin cells, although they are not derivatives of the neural crest. Oth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brain Natriuretic Peptide
Brain natriuretic peptide (BNP), also known as B-type natriuretic peptide, is a hormone secreted by cardiomyocytes in the heart ventricles in response to stretching caused by increased ventricular blood volume. BNP is one of the three natriuretic peptides, in addition to atrial natriuretic peptide ( ANP) and C-type natriuretic peptide ( CNP). BNP was first discovered in porcine brain tissue in 1988, which led to its initial naming as "brain natriuretic peptide", although subsequent research revealed that BNP is primarily produced and secreted by the ventricular myocardium (heart muscle) in response to increased ventricular blood volume and stretching. To reflect its true source, BNP is now often referred to as "B-type natriuretic peptide" while retaining the same acronym. The 32-amino acid polypeptide BNP-32 is secreted attached to a 76–amino acid N-terminal fragment in the prohormone called NT-proBNP (BNPT), which is biologically inactive. Once released, BNP binds to and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blood Pressure
Blood pressure (BP) is the pressure of Circulatory system, circulating blood against the walls of blood vessels. Most of this pressure results from the heart pumping blood through the circulatory system. When used without qualification, the term "blood pressure" refers to the pressure in a brachial artery, where it is most commonly measured. Blood pressure is usually expressed in terms of the systolic pressure (maximum pressure during one Cardiac cycle, heartbeat) over diastolic pressure (minimum pressure between two heartbeats) in the cardiac cycle. It is measured in Millimetre of mercury, millimetres of mercury (mmHg) above the surrounding atmospheric pressure, or in Pascal (unit), kilopascals (kPa). The difference between the systolic and diastolic pressures is known as pulse pressure, while the average pressure during a cardiac cycle is known as mean arterial pressure. Blood pressure is one of the vital signs—together with respiratory rate, heart rate, Oxygen saturation (me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heart (journal)
''Heart'' is a biweekly peer-reviewed medical journal covering all areas of cardiovascular medicine and surgery. It is the official journal of the British Cardiovascular Society. It was established in 1939 as the ''British Heart Journal'' and is published by the BMJ Group. The name was changed from ''British Heart Journal'' to ''Heart'' in 1996 with the start of volume 75. The editor-in-chief is Kazem Rahimi (University of Oxford). A sister journal, '' Open Heart'', was established in 2010 with the aim of covering cardiovascular research with less emphasis on novelty or priority. History In 2010, ''Heart'' established a sister journal, ''Heart Asia''. It was the official journal of the Asia Pacific Heart Association and aimed to focus on cardiovascular research in the Asia Pacific region. In 2019, the journal ceased publication. Abstracting and indexing The journal is abstracted and indexed by Index Medicus, Science Citation Index Expanded, EMBASE, and Scopus. According to th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heart Failure With Preserved Ejection Fraction
Heart failure with preserved ejection fraction (HFpEF) is a form of heart failure in which the ejection fraction – the percentage of the volume of blood ejected from the left ventricle with each heartbeat divided by the volume of blood when the left ventricle is maximally filled – is normal, defined as greater than 50%; this may be measured by echocardiography or cardiac catheterization. Approximately half of people with heart failure have preserved ejection fraction, while the other half have a reduction in ejection fraction, called heart failure with reduced ejection fraction (HFrEF). Risk factors for HFpEF include hypertension, hyperlipidemia, diabetes, smoking, and obstructive sleep apnea. Those with HFpEF have a higher prevalence of obesity, type 2 diabetes, hypertension, atrial fibrillation and chronic kidney disease than those with heart failure with reduced ejection fraction. The prevalence of HFpEF is expected to increase as more people develop obesity and other medic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cardiac Stress Test
A cardiac stress test is a cardiological examination that evaluates the cardiovascular system's response to external stress within a controlled clinical setting. This stress response can be induced through physical exercise (usually a treadmill) or intravenous pharmacological stimulation of heart rate. As the heart works progressively harder (stressed) it is monitored using an electrocardiogram (ECG) monitor. This measures the heart's electrical rhythms and broader electrophysiology. Pulse rate, blood pressure and symptoms such as chest discomfort or fatigue are simultaneously monitored by attending clinical staff. Clinical staff will question the patient throughout the procedure asking questions that relate to pain and perceived discomfort. Abnormalities in blood pressure, heart rate, ECG or worsening physical symptoms could be indicative of coronary artery disease. Stress testing does not accurately diagnose all cases of coronary artery disease, and can often indicate that it e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
