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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.
Baroreceptors are sensors located in the carotid sinus and in the aortic arch. They sense the blood pressure and relay the information to the brain, so that a proper blood pressure can be maintained.
Mitral stenosis is a valvular heart disease characterized by the narrowing of the opening of the mitral valve of the heart. It is almost always caused by rheumatic valvular heart disease. Normally, the mitral valve is about 5 cm2 during diastole. Any decrease in area below 2 cm2 causes mitral stenosis. Early diagnosis of mitral stenosis in pregnancy is very important as the heart cannot tolerate increased cardiac output demand as in the case of exercise and pregnancy. Atrial fibrillation is a common complication of resulting left atrial enlargement, which can lead to systemic thromboembolic complications like stroke.
The jugular venous pressure is the indirectly observed pressure over the venous system via visualization of the internal jugular vein. It can be useful in the differentiation of different forms of heart and lung disease. Classically three upward deflections and two downward deflections have been described.
Cardiac catheterization is the insertion of a catheter into a chamber or vessel of the heart. This is done both for diagnostic and interventional purposes.
The atrium is one of two upper chambers in the heart that receives blood from the circulatory system. The blood in the atria is pumped into the heart ventricles through the atrioventricular valves.
A pulmonary artery catheter (PAC), also known as a Swan-Ganz catheter or right heart catheter, is a balloon-tipped catheter that is inserted into a pulmonary artery in a procedure known as pulmonary artery catheterization or right heart catheterization. Pulmonary artery catheterization is a useful measure of the overall function of the heart particularly in those with complications from heart failure, heart attack, arrythmias or pulmonary embolism. It is also a good measure for those needing intravenous fluid therapy, for instance post heart surgery, shock, and severe burns. The procedure can also be used to measure pressures in the heart chambers.
In cardiac physiology, preload is the amount of sarcomere stretch experienced by cardiac muscle cells, called cardiomyocytes, at the end of ventricular filling during diastole. Preload is directly related to ventricular filling. As the relaxed ventricle fills during diastole, the walls are stretched and the length of sarcomeres increases. Sarcomere length can be approximated by the volume of the ventricle because each shape has a conserved surface-area-to-volume ratio. This is useful clinically because measuring the sarcomere length is destructive to heart tissue. It requires cutting out a piece of cardiac muscle to look at the sarcomeres under a microscope. It is currently not possible to directly measure preload in the beating heart of a living animal. Preload is estimated from end-diastolic ventricular pressure and is measured in millimeters of mercury (mmHg).
Pulsus paradoxus, also paradoxic pulse or paradoxical pulse, is an abnormally large decrease in stroke volume, systolic blood pressure and pulse wave amplitude during inspiration. The normal fall in pressure is less than 10 mmHg. When the drop is more than 10 mmHg, it is referred to as pulsus paradoxus. Pulsus paradoxus is not related to pulse rate or heart rate, and it is not a paradoxical rise in systolic pressure. The normal variation of blood pressure during breathing/respiration is a decline in blood pressure during inhalation and an increase during exhalation. Pulsus paradoxus is a sign that is indicative of several conditions, including cardiac tamponade, chronic sleep apnea, croup, and obstructive lung disease.
The Bainbridge reflex or Bainbridge effect, also called the atrial reflex, is an increase in heart rate due to an increase in central venous pressure. Increased blood volume is detected by stretch receptors located in both sides of atria at the venoatrial junctions.
Venous return is the rate of blood flow back to the heart. It normally limits cardiac output.
Right atrial pressure (RAP) is the blood pressure in the right atrium of the heart. RAP reflects the amount of blood returning to the heart and the ability of the heart to pump the blood into the arterial system. RAP is often nearly identical to central venous pressure (CVP), although the two terms are not identical, as a pressure differential can sometimes exist between the venae cavae and the right atrium. CVP and RAP can differ when venous tone is altered. This can be graphically depicted as changes in the slope of the venous return plotted against right atrial pressure.
A split S2 is a finding upon auscultation of the S2 heart sound.
Volume overload refers to the state of one of the chambers of the heart in which too large a volume of blood exists within it for it to function efficiently. Ventricular volume overload is approximately equivalent to an excessively high preload. It is a cause of cardiac failure.
Low pressure baroreceptors are baroreceptors that relay information derived from blood pressure within the autonomic nervous system. They are stimulated by stretching of the vessel wall. They are located in large systemic veins and in the walls of the atria of the heart, and pulmonary vasculature. Low pressure baroreceptors are also referred to as volume receptors and cardiopulmonary baroreceptors.
Cardiac physiology or heart function is the study of healthy, unimpaired function of the heart: involving blood flow; myocardium structure; the electrical conduction system of the heart; the cardiac cycle and cardiac output and how these interact and depend on one another.
A plot of a system's pressure versus volume has long been used to measure the work done by the system and its efficiency. This analysis can be applied to heat engines and pumps, including the heart. A considerable amount of information on cardiac performance can be determined from the pressure vs. volume plot. A number of methods have been determined for measuring PV-loop values experimentally.
The Senning procedure is an atrial switch heart operation performed to treat transposition of the great arteries. It is named after its inventor, the Swedish cardiac surgeon Åke Senning (1915–2000), also known for implanting the first permanent cardiac pacemaker in 1958.
quantium Medical Cardiac Output (qCO) uses impedance cardiography in a simple, continuous, and non-invasive way to estimate the cardiac output (CO) and other hemodynamic parameters such as the stroke volume (SV) and cardiac index (CI). The CO estimated by the qCO monitor is referred to as the "qCO". The impedance plethysmography allows determining changes in volume of the body tissues based on the measurement of the electric impedance at the body surface.
The main pathophysiology of heart failure is a reduction in the efficiency of the heart muscle, through damage or overloading. As such, it can be caused by a wide number of conditions, including myocardial infarction, hypertension and cardiac amyloidosis. Over time these increases in workload will produce changes to the heart itself:
References
- ↑ "Central Venous Catheter Physiology". Archived from the original on 2008-08-21. Retrieved 2009-02-27.
- ↑ Kumar A, Anel R, Bunnell E, Habet K, Zanotti S, Marshall S, et al. (2004). "Pulmonary artery occlusion pressure and central venous pressure fail to predict ventricular filling volume, cardiac performance, or the response to volume infusion in normal subjects" (PDF). Crit Care Med. 32 (3): 691–699. doi:10.1097/01.ccm.0000114996.68110.c9. PMID 15090949. S2CID 41905070.
- ↑ Marik P, Baram M, Vahid B (July 2008). "Does Central Venous Pressure Predict Fluid Responsiveness?" (PDF). Chest. 134 (1): 1351–1352. doi:10.1378/chest.08-1846. PMID 19059974. Archived from the original (PDF) on 2014-06-11. Retrieved 2012-12-09.
- ↑ Sala-Mercado JA, Moslehpour M, Hammond RL, Ichinose M, Chen X, Evan S, O'Leary DS, Mukkamala R (June 2014). "Stimulation of the Cardiopulmonary Baroreflex Enhances Ventricular Contractility in Awake Dogs: A Mathematical Analysis Study". American Journal of Physiology. Regulatory, Integrative and Comparative Physiology. 307 (4): R455–R464. doi:10.1152/ajpregu.00510.2013. PMC 4137157 . PMID 24944253.
- ↑ Table 30-1 in: Goers TA, Klingensmith ME, Chen LE, Glasgow SC (2008). The Washington Manual of Surgery. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins. ISBN 978-0-7817-7447-5.
