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Diastole Schmeltziana
Diastole ( ) is the relaxed phase of the cardiac cycle when the chambers of the heart are re-filling 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 systol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heart Diasystole
The heart is a muscular organ in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, 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 chest. In humans, other mammals, and birds, the heart is divided into four chambers: upper left and right atria and lower left and right ventricles. Commonly the right atrium and ventricle are referred together as the right heart and their left counterparts as the left heart. Fish, in contrast, have two chambers, an atrium and a ventricle, while most reptiles have three chambers. In a healthy heart blood flows one way through the heart due to heart valves, which prevent backflow. The heart is enclosed in a protective sac, the pericardium, which also contains a small amount of fluid. The wall of ... [...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, and currently defined as exactly pascals. It is denoted mmHg or mm Hg. Although not an SI unit, the millimetre of mercury is still routinely used in medicine, meteorology, aviation, and many other scientific fields. One millimetre of mercury is approximately 1 Torr, which is of standard atmospheric pressure ( ≈ ). Although the two units are not equal, the relative difference (less than ) is negligible for most practical uses. History For much of human history, the pressure of gases like air was ignored, denied, or taken for granted, but as early as the 6th century BC, Greek philosopher Anaximenes of Miletus claimed that all things are made of air that is simply changed by varying levels of pressure. He could observe water evaporating, changing to a gas, and felt that this applied even to solid matter. More c ... [...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 ammount of blood present in ventricle at the end of diastole systole. 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 ... [...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 a ... [...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. HFpEF is characterized by abnormal diastolic function: there is an increase in the stiffness of the left ventricle, which causes a decrease in left ventricular relaxation during diastole, with resultant increased pressure and/or impaired filling. There is an increased risk for atrial fi ... [...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 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 osmotic forces drag water out of the body's blood circulation and into the urine along with the sodium. Many diuretic 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 natriuretic peptide * C-type natriuretic peptide Natriuretic peptide ... [...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. Other neu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brain Natriuretic Peptide
Brain natriuretic peptide 32 (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. Along with NT-proBNP, BNP is one of two natriuretic peptides. The 32-amino acid polypeptide BNP 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 activates the atrial natriuretic factor receptor NPRA, and to a lesser extent NPRB, in a fashion similar to atrial natriuretic peptide (ANP) but with 10-fold lower affinity. The biological half-life of BNP, however, is twice as long as that of ANP, and that of NT-proBNP is even longer, making these peptides better targets than ANP for diagnostic blood testing. The physiologic actions of BNP are similar to those of ANP and include decrease in systemic vascular resistance and central venous pressure as wel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blood Pressure
Blood pressure (BP) is the pressure of 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 the large arteries. Blood pressure is usually expressed in terms of the systolic pressure (maximum pressure during one heartbeat) over diastolic pressure (minimum pressure between two heartbeats) in the cardiac cycle. It is measured in millimeters of mercury ( mmHg) above the surrounding atmospheric pressure. Blood pressure is one of the vital signs—together with respiratory rate, heart rate, oxygen saturation, and body temperature—that healthcare professionals use in evaluating a patient's health. Normal resting blood pressure, in an adult is approximately systolic over diastolic, denoted as "120/80 mmHg". Globally, the average blood pressure, age standardized, has remained about the same since 1 ... [...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 Catherine Otto (University of Washington). 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 ... [...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. HFpEF is characterized by abnormal diastolic function: there is an increase in the stiffness of the left ventricle, which causes a decrease in left ventricular relaxation during diastole, with resultant increased pressure and/or impaired filling. There is an increased risk for atrial fi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cardiac Stress Test
A cardiac stress test (also referred to as a cardiac diagnostic test, cardiopulmonary exercise test, or abbreviated CPX test) is a cardiological test that measures the heart's ability to respond to external stress in a controlled clinical environment. The stress response is induced by exercise or by intravenous pharmacological stimulation. Cardiac stress tests compare the coronary circulation while the patient is at rest with the same patient's circulation during maximum cardiac exertion, showing any abnormal blood flow to the myocardium (heart muscle tissue). The results can be interpreted as a reflection on the general physical condition of the test patient. This test can be used to diagnose coronary artery disease (also known as ischemic heart disease) and assess patient prognosis after a myocardial infarction (heart attack). Exercise-induced stressors are most commonly either exercise on a treadmill or pedalling a stationary exercise bicycle ergometer. The level of stress ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
