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Isovolumic Relaxation Time
Isovolumic relaxation time (IVRT) is an interval in the cardiac cycle, from the aortic component of the second heart sound, that is, closure of the aortic valve, to onset of filling by opening of the mitral valve."Inductance cardiography (thoracocardiography): A novel, noninvasive technique for monitoring left ventricular filling". ''Journal of Critical Care'', Volume 14, Issue 4, Pages 177–185 It can be used as an indicator of diastolic dysfunction. It can be measured by simultaneous Doppler echocardiography and M-mode sonography, or better still, by simultaneous phonocardiogram and transmitral Doppler.anaesthetist.com >Diastolic dysfunctionLara Hopley and Jo van Schalkwyk. Date of last update: 2009-06-05 Prolonged IVRT indicates poor myocardial relaxation. A normal IVRT is about 70 ± 12 ms, and approximately 10 ms longer in people over forty years. In abnormal relaxation, IVRT is usually in excess of 110 ms. With restrictive ventricular filling In semanti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wiggers Diagram
A Wiggers diagram, named after its developer, Carl Wiggers, is a unique diagram that has been used in teaching cardiac physiology for more than a century. In the Wiggers diagram, the X-axis is used to plot time subdivided into the cardiac phases, while the Y-axis typically contains the following on a single grid: * Blood pressure ** Aortic pressure ** Ventricular pressure ** Atrial pressure * Ventricular volume * Electrocardiogram * Arterial flow (optional) * Heart sounds (optional) The Wiggers diagram clearly illustrates the coordinated variation of these values as the heart beats, assisting one in understanding the entire cardiac cycle. Events Note that during isovolumetric/isovolumic contraction and relaxation, all the heart valves are closed; at no time are all the heart valves open. *S3 and S4 heart sounds are associated with pathologies and are not routinely heard. Additional images File:Heart systole.svg, Ventricular systole File:Heart diasystole.svg, Cardia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cardiac Cycle
The cardiac cycle is the performance of the heart, human heart from the beginning of one heartbeat to the beginning of the next. It consists of two periods: one during which the heart muscle relaxes and refills with blood, called diastole, following a period of robust contraction and pumping of blood, called systole. After emptying, the heart relaxes and expands to receive another influx of blood returning from the lungs and other systems of the body, before again contracting. Assuming a healthy heart and a typical rate of 70 to 75 beats per minute, each cardiac cycle, or heartbeat, takes about 0.8 second to complete the cycle. Duration of the cardiac cycle is inversely proportional to the heart rate. Description There are two atrium (heart), atrial and two ventricle (heart), ventricle chambers of the heart; they are paired as the heart#Left heart, left heart and the heart#Right heart, right heart—that is, the left atrium with the left ventricle, the right atrium with the r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heart Sound
Heart sounds are the noises generated by the beating heart and the resultant flow of blood through it. Specifically, the sounds reflect the turbulence created when the heart valves snap shut. In cardiac auscultation, an examiner may use a stethoscope to listen for these unique and distinct sounds that provide important auditory data regarding the condition of the heart. In healthy adults, there are two normal heart sounds, often described as a ''lub'' and a ''dub'' that occur in sequence with each heartbeat. These are the first heart sound (S1) and second heart sound (S2), produced by the closing of the atrioventricular valves and semilunar valves, respectively. In addition to these normal sounds, a variety of other sounds may be present including heart murmurs, adventitious sounds, and gallop rhythms S3 and S4. Heart murmurs are generated by turbulent flow of blood and a murmur to be heard as turbulent flow must require pressure difference of at least 30 mm of Hg betwee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aortic Valve
The aortic valve is a valve in the heart of humans and most other animals, located between the left ventricle and the aorta. It is one of the four valves of the heart and one of the two semilunar valves, the other being the pulmonary valve. The aortic valve normally has three cusps or leaflets, although in 1–2% of the population it is found to congenitally have two leaflets. The aortic valve is the last structure in the heart the blood travels through before stopping the flow through the systemic circulation. Structure The aortic valve normally has three cusps however there is some discrepancy in their naming. They may be called the left coronary, right coronary and non-coronary cusp. Some sources also advocate they be named as a left, right and posterior cusp. Anatomists have traditionally named them the left posterior (origin of left coronary), anterior (origin of the right coronary) and right posterior. The three cusps, when the valve is closed, contain a sinus called ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diastolic Dysfunction
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 medi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Doppler Echocardiography
Doppler echocardiography is a procedure that uses Doppler ultrasonography to examine the heart. An echocardiogram uses high frequency sound waves to create an image of the heart while the use of Doppler technology allows determination of the speed and direction of blood flow by utilizing the Doppler effect. An echocardiogram can, within certain limits, produce accurate assessment of the direction of blood flow and the velocity of blood and cardiac tissue at any arbitrary point using the Doppler effect. One of the limitations is that the ultrasound beam should be as parallel to the blood flow as possible. Velocity measurements allow assessment of cardiac valve areas and function, any abnormal communications between the left and right side of the heart, any leaking of blood through the valves (valvular regurgitation), calculation of the cardiac output and calculation of E/A ratio [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Medical Ultrasonography
Medical ultrasound includes Medical diagnosis, diagnostic techniques (mainly medical imaging, imaging) using ultrasound, as well as therapeutic ultrasound, therapeutic applications of ultrasound. In diagnosis, it is used to create an image of internal body structures such as tendons, muscles, joints, blood vessels, and internal organs, to measure some characteristics (e.g., distances and velocities) or to generate an informative audible sound. The usage of ultrasound to produce visual images for medicine is called medical ultrasonography or simply sonography, or echography. The practice of examining pregnant women using ultrasound is called obstetric ultrasonography, and was an early development of clinical ultrasonography. The machine used is called an ultrasound machine, a sonograph or an echograph. The visual image formed using this technique is called an ultrasonogram, a sonogram or an echogram. Ultrasound is composed of sound waves with frequency, frequencies greater than ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phonocardiogram
A phonocardiogram (or PCG) is a plot of high fidelity, high-fidelity recording of the heart sounds, sounds and heart murmur, murmurs made by the heart with the help of the machine called the phonocardiograph; thus, phonocardiography is the recording of all the sounds made by the heart during a cardiac cycle. Medical use Heart sounds result from vibrations created by the closure of the heart valves. There are at least two; the first (S1) is produced when the atrioventricular valves (tricuspid and mitral) close at the beginning of Systole (medicine), systole and the second (S2) when the aortic valve and pulmonary valve (semilunar valves) close at the end of systole. Phonocardiography allows the detection of subaudible sounds and murmurs and makes a permanent record of these events. In contrast, the stethoscope cannot always detect all such sounds or murmurs and provides no record of their occurrence. The ability to quantification (science), quantitate the sounds made by the heart p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Restrictive Ventricular Filling
In semantics, a grammatical modifier, modifier is said to be restrictive (or ''defining'') if it restricts the reference#Semantics, reference of its head (linguistics), head. For example, in "the red car is fancier than the blue one", ''red'' and ''blue'' are restrictive, because they restrict which cars ''car'' and ''one'' are referring to. ("The car is fancier than the one" would make little sense.) By contrast, in "John's beautiful mother", ''beautiful'' is non-restrictive; "John's mother" identifies her sufficiently, whereas "beautiful" only serves to add more information. Restrictive modifiers are also called ''defining'', ''identifying'', ''essential'', or ''necessary''; non-restrictive ones are also called ''non-defining'', ''non-identifying'', ''descriptive'', or ''unnecessary'' (though this last term can be misleading). In certain cases, generally when restrictiveness is marked syntax, syntactically through the lack of commas, restrictive modifiers are called ''integrated' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isovolumetric Contraction
In cardiac physiology, isometric contraction is an event occurring in early systole during which the ventricles contract with no corresponding volume change ( isometrically). This short-lasting portion of the cardiac cycle takes place while all heart valves are closed. The inverse operation is isovolumetric relaxation diastole with all valves optimally closed. Description In a healthy young adult, blood enters the atria and flows to the ventricles via the opened atrioventricular valves (tricuspid and mitral valves). Atrial contraction rapidly follows, actively pumping about 30% of the returning blood. As diastole ends, the ventricles begin depolarizing and, while ventricular pressure starts to rise owing to contraction, the atrioventricular valves close in order to prevent backflow to the atria. At this stage, which corresponds to the R peak or the QRS complex seen on an ECG, the semilunar valves (aortic and pulmonary valves) are also closed. The net result is that, while cont ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
