heart(redirected from Atria of the heart)
Also found in: Dictionary, Thesaurus, Legal, Encyclopedia.
Exercise stress testing is a valuable tool for detecting persons who have some degree of coronary heart disease. The test subject performs maximal exercise while being monitored by ECG. A positive stress test occurs when the subject cannot sustain the exercise for the duration of the test, cannot attain a normal maximal heart rate, or shows ECG changes indicative of ischemia. When stress testing is used for screening purposes, it is not diagnostic. However, persons with a positive stress test are 13 times more likely to develop significant coronary artery or heart disease and should work to reduce their risk factors. Stress testing is also used to evaluate the severity of known coronary disease and to guide the rehabilitation of a patient with coronary disease.
Phonocardiography is the recording of heart sounds and murmurs. It is more precise than auscultation with a stethoscope because it provides a permanent visual record that can be used to obtain precise timing information and can be used as baseline data for comparison with later findings.
Echocardiography is a type of diagnostic ultrasonography that provides information about the structure and function of the heart. It is a comfortable technique for the patient and is capable of establishing a diagnosis for several types of heart disease, especially those involving the valves. Types include M-mode, Doppler, and transesophageal echocardiography.
Several types of radioisotope examination are used to detect heart disease. A radioisotope imaging agent is injected into the patient, and a scintillation camera is then used to make an image of the distribution of radioactivity.
Thallium 201 has an affinity for heart tissue; when injected intravenously, it is carried to areas with adequate perfusion. Myocardial infarcts and areas of acute ischemia or scarring appear as “cold spots” (areas of no uptake of thallium) on the scintigram. When the isotope is injected during maximal exercise in an exercise stress test, the scan shows areas of inadequate perfusion and is a better indicator of coronary disease than a stress test alone.
Radiopharmaceuticals that label the blood pool can be used with a computerized scintillation camera to evaluate ventricular performance. Images of the first pass of the radioisotope through the heart can be used to determine the cardiac output and ejection fraction, the size of the ventricles, and regional wall motion.
The imaging agents used for bone scans, such as technetium 99m pyrophosphate or diphosphonate, also have an affinity for areas of acute ischemic tissue damage. “Hot spots” on the scintigram (areas of isotope uptake) show areas of acute infarction. The scan is usually negative by approximately 6 days after an infarction.
Cardiac catheterization is an invasive technique used when definitive data are required to decide whether heart disease should be treated medically, surgically, or through interventional cardiology techniques such as percutaneous transluminal angioplasty, stents, or valvuloplasty. A catheter is inserted into a vein or artery, usually the brachial artery or the femoral vein or artery, and guided into the heart. Tracings of the pressure pulses within the chambers during the heart cycle are obtained. Cardiac output, pulmonary artery pressures, the orifice area of valves, and the degree of left-to-right shunting can be determined.
Angiocardiography is the x-ray examination of the heart after injection of a radiopaque contrast medium through a catheter at various locations in the heart. The films show the size and motion of the heart chambers and can demonstrate aortic or mitral regurgitation. In coronary arteriography the contrast medium is injected through a catheter into the orifice of each coronary artery. The films show atherosclerotic obstructions of the arteries and are useful in planning coronary bypass surgery, percutaneous transluminal angioplasty, or stents.
All these contributions to the control and correction of cardiovascular diseases are important in the reduction of mortality rates and improvement in patients' quality of life. Nevertheless, it is also important for prevention that there be an improvement of the general public's awareness of the causes and risk factors of cardiac disorders. Major risk factors that can be avoided, modified, or corrected include cigarette smoking, elevated blood lipids, obesity, habitual dietary excesses, lack of exercise, hypertension, and excessive stress. Health professionals can promote reduction in the incidence of heart disease by educating the public about these risk factors and by encouraging active participation in preventive measures, particularly in those that involve changes in lifestyle.
heartSee Abiomed implantable heart, Athlete's heart, Baby Fae heart, Bleeding heart, Crisscross heart, Dextroposition heart, Depraved heart, Egg-shaped heart, Flabby heart, Flask-shaped heart, Holiday heart, Left heart, Mongolian heart, Old soldier's heart, Penn State heart, Right heart, Sabot heart, Second heart, Stone heart, Swinging heart, Water bottle heart.
HEARTCardiology A clinical trial–Healing & Early Afterload Reducing Therapy
Synonym(s): cor [TA] , coeur.
The upper right and left atria are thin-walled receiving chambers separated by the interatrial septum. The lower right and left ventricles are thick-walled pumping chambers separated by the interventricular septum; normally the right side has no communication with the left. The right side receives deoxygenated blood via the venae cavae from the body and pumps it to the lungs; the left side receives oxygenated blood from the lungs and pumps it via the aorta and arteries to the body. Contraction of the heart chambers is called systole; relaxation with accompanying filling with blood is called diastole. The sequence of events that occurs in a single heartbeat is called the cardiac cycle, with atrial systole followed by ventricular systole. For a heart rate of 70 beats per minute, each cycle lasts about 0.85 sec.
In the healthy state, all four cardiac valves prevent backflow of blood. The atrioventricular valves are at the openings between each atrium and ventricle; the tricuspid valve, between the right atrium and ventricle; and the bicuspid or mitral valve, between the left atrium and ventricle. The pulmonary semilunar valve is at the opening of the right ventricle into the pulmonary artery; the aortic semilunar valve is at the opening of the left ventricle into the aorta.
In adults, the cardiac output varies from 5 L/min at rest to as much as 20 L/min during vigorous exercise. At the rate of 72 times each minute, the adult human heart beats 104,000 times a day, 38,000,000 times a year. Every stroke forces approx. 5 cu in (82 ml) of blood out into the body, amounting to 500,000 cu in (8193 L) a day. In terms of work, this is the equivalent of raising 1 ton (907 kg) to a height of 41 ft (12.5 m) every 24 hr.
The myocardium receives its blood supply from the coronary arteries that arise from the ascending aorta. Blood from the myocardium drains into several cardiac veins.
The heart initiates its own beat, usually from 60 to 80 beats per minute, but the rate may be changed by impulses from the cardiac centers in the medulla oblongata. Accelerator impulses are carried by sympathetic nerves. Preganglionic neurons in the thoracic spinal cord synapse with postganglionic neurons in the cervical ganglia of the sympathetic trunk; their axons continue to the heart. Sympathetic impulses are transmitted to the sinoatrial (SA) node, atrioventricular (AV) node, bundle of His, and myocardium of the ventricles and increase heart rate and force of contraction. Inhibitory impulses are carried by the vagus nerves (parasympathetic). Preganglionic neurons (vagus) originating in the medulla synapse with postganglionic neurons in terminal ganglia in the wall of the heart. Parasympathetic impulses are transmitted to the SA and AV nodes and decrease the heart rate. Sensory nerves from the heart serve for the sensation of pain, which is caused by an insufficient supply of oxygen to the myocardium. The vagus and glossopharyngeal are the sensory nerves for reflex changes in heart rate. These nerves arise from pressoreceptors or chemoreceptors in the aortic arch and carotid sinus, respectively.
Listening to the heart with a stethoscope reveals the intensity, quality, and rhythm of the heart sounds and detects any adventitious sounds (e.g., murmurs or pericardial friction). The two separate sounds heard by the use of a stethoscope over the heart have been represented by the syllables “lubb, ” “dupp.” The first sound (systolic), which is prolonged and dull, results from the contraction of the ventricle, tension of the atrioventricular valves, and the impact of the heart against the chest wall and is synchronous with the apex beat and carotid pulse. The first sound is followed by a short pause, and then the second sound (diastolic) is heard, resulting from the closure of the aortic and pulmonary valves. This sound is short and high pitched. After the second sound there is a longer pause before the first is heard again. A very useful technique for listening to the variation in sounds between one area and another is to move the stethoscope in small steps from site to site.
The patient should be recumbent when the examination begins. After all possible signs have been elicited, the examination should be repeated with the patient sitting, standing, or leaning forward, and any variations from this change of position should be noted. Auscultation is performed first while the patient is breathing naturally, next while he holds the breath in both deep inspiration and expiration, and finally while the patient takes three or four forced inspirations. By listening over the entire thoracic cavity, the examiner should try to localize the points at which heart sounds, both normal and abnormal, are heard with the greatest intensity. The examination should proceed from below upward and from left to right.
The normal location of valves should be noted for auscultation. The aortic valve is in the third intercostal space, close to the left side of the sternum; the pulmonary valve is in front of the aorta, behind the junction of the third costal cartilage with the sternum, on the left side. The tricuspid valve is located behind the middle of the sternum about the level of the fourth costal cartilage. Finally, the mitral valve is behind the third intercostal space about 1 in (2.5 cm) to the left of the sternum.
Both heart sounds either are heard better or are actually accentuated in increased heart action from any cause, normal or abnormal (e.g., anemia, vigorous exercise, cardiac hypertrophy, thin chest walls, and lung consolidation as found in pneumonia). Accentuation of the aortic second sound results from hypertrophy of the left ventricle, increased arterial resistance (as in arteriosclerosis with hypertension), or aortic aneurysm. Accentuation of the pulmonary second sound results from pulmonary obstruction (as in emphysema, pneumonia, or hypertrophy of the right ventricle). Both heart sounds are poorly heard or are actually decreased in intensity in general obesity, general debility, degeneration or dilatation of the heart, pericardial or pleural effusion, and emphysema.
The reduplication of heart sounds is probably due to a lack of synchronous action in the valves of both sides of the heart. It results from many conditions but notably from increased resistance in the systemic or the pulmonary circulation (as in arteriosclerosis and emphysema). It is also frequently noted in mitral stenosis and pericarditis.
A murmur (an abnormal sound heard over the heart or blood vessels) may result from obstruction or regurgitation at the valves following endocarditis; dilatation of the ventricle or relaxation of its walls rendering the valves relatively insufficient; aneurysm; a change in the blood constituents (as in anemia); roughening of the pericardial surfaces (as in pericarditis); and irregular action of the heart. Murmurs produced within the heart are called endocardial; those outside, exocardial; those produced in aneurysms, bruits; those produced by anemia, hemic murmurs.
Hemic murmurs, which are soft and blowing and usually systolic, are heard best over the pulmonary valves. They are associated with symptoms of anemia.
An aneurysmal murmur (bruit) is usually loud and booming, systolic, and heard best over the aorta or base of the heart. It is often associated with an abnormal area of dullness and pulsation and with symptoms resulting from pressure on neighboring structures.
Pericardial friction sounds are superficial, rough, and creaking, to and fro in tempo, and not transmitted beyond the precordium. These sounds may be modified by the pressure of the stethoscope.
Murmur intensity and configuration: The intensity (loudness) of murmurs may be graded from I to VI as follows: (1) Grade I–faint, audible only with intense listening in a quiet environment; (2) Grade II–quiet but immediately audible; (3) Grade III–moderately loud; (4) Grade IV–quite loud; a thrill (like the purring of a cat) usually felt over the heart; (5) Grade V–loud enough to be heard with the stethoscope not completely in contact with the chest wall; and (6) Grade VI–loud enough to be heard with the stethoscope close to but not actually touching the chest.
The configuration of sound intensity of a murmur may begin low and rise in intensity (crescendo) or be relatively loud and then decrease in intensity (decrescendo) or some combination of those features or may exhibit the same intensity from beginning to end.
This process not only determines position, force, extent, and rhythm of the apex beat but also detects any fremitus or thrill. A thrill is a vibratory sensation like that when the hand is placed on the back of a purring cat. Thrills at the base of the heart may result from valvular lesions, atheroma of the aorta, aneurysm, and roughened pericardial surfaces (as in pericarditis). A presystolic thrill at the apex is almost pathognomonic of mitral stenosis. In children especially, a precordial bulge, substernal thrust, or apical heave suggests cardiac enlargement.
This procedure determines the shape and extent of cardiac dullness. The normal area of superficial or absolute percussion dullness (the part uncovered by the lung) is detected by light percussion and extends from the fourth left costosternal junction to the apex beat; from the apex beat to the juncture of the xiphoid cartilage with the sternum; and thence up the left border of the sternum. The normal area of deep percussion dullness (the heart projected on the chest wall) is detected by firm percussion and extends from the third left costosternal articulation to the apex beat; from the apex beat to the junction of the xiphoid cartilage with the sternum; and thence up the right border of sternum to the third rib. The lower level of cardiac dullness fuses with the liver dullness and can rarely be determined. The area of cardiac dullness is increased in hypertrophy and dilation of the heart and in pericardial effusion; it is diminished in emphysema, pneumothorax, and pneumocardium.
heartThe twin-sided, four-chambered controlled muscular pump that, by means of regular rhythmical tightening (contractions) of the chambers and the action of valves, maintains the twin circulations of blood to the lungs and to the rest of the body. The right side of the heart pumps blood through the lungs and back to the left side. The left side pumps the blood returning from the lungs through all parts of the body and back to the right side.
heartthe muscular pump of the BLOOD CIRCULATORY SYSTEM. In those invertebrates that possess a heart (e.g. ARTHROPODS, ANNELIDS, MOLLUSCS, ECHINODERMS) the heart is composed of several chambers and lies dorsal to the gut. In vertebrates the heart is made of special CARDIAC MUSCLE and lies in a ventral position surrounded by the PERICARDIUM. The five classes of vertebrates show an increasing complexity of structure, from the simple S-shaped heart with one ATRIUM and one VENTRICLE (2) found in fish, through the amphibians and most reptiles where the heart is divided into two atria but retains a single ventricle, and on to the birds and mammals where the heart shows complex separation into two sides with two atria and two ventricles. The main features of the human heart are:
- the right side pumps blood around the pulmonary (lung) circulation for oxygenation, the left side pumping blood around the systemic (body) circulation where it becomes deoxygenated.
- blood from the body enters the right atrium via the superior vena cava (upper body) and inferior vena cava (lower body). A coronary sinus also drains into the right atrium bringing blood from the heart itself. The right atrium squeezes blood through the atrioventricular (AV) opening into the muscular right ventricle. finally, blood is ejected into the single opening of the pulmonary artery which splits to go to the two lungs.
- blood enters the left atrium from four pulmonary veins and passes through the left AV opening into the left ventricle. This has a much thicker wall than the right ventricle, reflecting its requirement for greater power. Blood leaves the left ventricle by one great vessel, the AORTA, which supplies all parts of the body, including the heart.
- flow of blood through the heart is in one direction only, due to the presence of various valves. Back-flow from ventricles to atria is prevented by AV valves, the tricuspid valve on the right side with three flaps, and the BICUSPID (3) valve on the left side with two flaps, both valves held in place by cords of connective tissue, the ‘chordae tendinae’. Back-flow from arteries to the ventricles is prevented by semilunar valves.
- various nerve areas connected with contraction are located in the heart (see HEART, CARDIAC CYCLE): (i) the sinoatrial node (SAN) or ‘pacemaker’ located in the wall of the right atrium near the entry of the venae cavae; (ii) the atrioventricular node (AVN) at the junction of all four heart chambers; (iii) the atrioventricular bundle, or bundle of His, running down the interventricular septum from the AVN; and (iv) a network of Purkinje tissue and other fibres spreading out from the bundle of His across the walls of both ventricles. See Fig. 189 .
Other nerve areas are situated in or near the heart: (i) baroreceptors in the walls of the heart, in the aortic arch, the carotid sinus, venae cavae and pulmonary veins where they enter the atria. Such sensory receptors are stimulated by stretching of the structure in which they are found, resulting in a decrease in blood pressure. (ii) chemoreceptors sensitive to blood CO2 levels are found in the AORTIC BODY and CAROTID BODY.
Patient discussion about heart
Q. how does it feel to heart promblems answer to my question then talk to me
Other manifestations may include fainting (called syncope) either spontaneously or after exercise, edema (swelling) of the legs and various other non specific complaints.
The manifestations depend, of course, on the specific disease and the various characteristics of the patient (age, sex etc.)
You may read more here:
Q. What happens to my heart when I exercise? My senior told me that exercise is good for health and especially for heart. What happens to my heart when I exercise?
Q. Is garlic helpful in heart ailments? I have heard that garlic is very good for cardiac health and using in curries or cooked with foods will be helpful. I have also heard that it has anti-inflammatory substances and also helps in weight loss. Is garlic helpful in heart ailments?