Heart sounds 237412 225560604 2008-07-14T09:07:21Z 137.189.4.1 /* S1 */ [[Image:Gray1216.svg|thumb|400px|Front of [[thorax]], showing surface relations of [[bone|bones]], [[lungs]] (purple), [[pleura]] (blue), and [[heart]] (red outline). [[Heart valves]] are labeled with "B", "T", "A", and "P".<BR><BR>First heart sound: caused by atrioventricular valves - [[Bicuspid valve|Bicuspid/Mitral]] (B) and [[Tricuspid valve|Tricuspid]] (T). <BR><BR>Second heart sound caused by semilunar valves -- [[Aortic valve|Aortic]] (A) and [[Pulmonary valve|Pulmonary/Pulmonic]] (P).]] [[Image:Gray1218.png|thumb|250px|Diagram showing relations of opened heart to front of thoracic wall. Ant. Anterior segment of [[tricuspid valve]]. A O. [[Aorta]]. A.P. Anterior [[papillary muscle]]. In. [[Innominate artery]]. L.C.C. Left [[common carotid artery]]. L.S. Left [[subclavian artery]]. L.V. [[Left ventricle]]. P.A. [[Pulmonary artery]]. R.A. [[Right atrium]]. R.V. [[Right ventricle]]. V.S. [[Ventricular septum]].]] The '''heart sounds''' are the noises ([[sound]]) generated by the beating [[heart]] and the resultant flow of blood through it. This is also called a '''heartbeat'''. In cardiac [[auscultation]], an examiner uses a [[stethoscope]] to listen for these sounds, which provide important information about the condition of the heart. In healthy adults, there are two normal heart sounds often described as a ''lub'' and a ''dub'' (or ''dup''), that occur in sequence with each heart beat. These are the '''first heart sound''' (S<sub>1</sub>) and '''second heart sound''' (S<sub>2</sub>), produced by the turbulant flow against the closed [[Heart valves#Atrioventricular_valves|AV valves]] and [[Heart valve#Semilunar_valves|semilunar valves]] respectively. In addition to these normal sounds, a variety of other sounds may be present including ''[[heart murmurs]]'', ''[[Adventitia|adventitious sounds]]'', and [[gallop rhythm]]s [[third heart sound|S<sub>3</sub>]] and [[Fourth heart sound|S<sub>4</sub>]]. [[Heart murmur|Heart murmurs]] are also generated by turbulent flow of blood, which may occur inside or outside the heart, but the sound has different characteristics than normal heart sounds. Murmurs may be ''physiological'' (benign) or ''pathological'' (abnormal). Abnormal murmurs can be caused by [[stenosis]] restricting the opening of a heart valve, resulting in turbulence as blood flows through it. Valve ''insufficiency'' (or ''regurgitation'') allows backflow of blood when the incompetent valve closes with only partial effectiveness. Different murmurs are audible in different parts of the [[cardiac cycle]], depending on the cause of the murmur. ==Normal heart sounds== Normal heart sounds are asscociated with heart valves closing causing changes in blood flow. ===S<sub>1</sub>=== The first heart tone, or '''S<sub>1</sub>''', forms the "lub" of "lub-dub" and is composed of components M<sub>1</sub> and T<sub>1</sub>). It is caused by the sudden block of reverse blood flow due to closure of the atrioventricular [[heart valves |valves]], i.e. [[mitral valve |mitral]] and [[tricuspid valve |tricuspid]], at the beginning of ventricular contraction, or [[systole]]. When the pressure in the [[ventricle (heart)|ventricle]]s rises above the pressure in the [[Atrium (heart)|atria]], venous blood flow entering the ventricles is pushed back toward the atria, catching the valve leaflets, closing the inlet valves and preventing [[regurgitation (circulation)|regurgitation]] of blood from the ventricles back into the atria. The '''S<sub>1</sub>''' sound results from reverberation within the blood associated with the sudden block of flow reversal by the valves. <ref name="Bates">"The Cardiovascular System." Bates, B. A Guide to Physical Examination and History Taking. 9h Ed. 2005.</ref> ===S<sub>2</sub>=== The second heart tone, or '''S<sub>2</sub>''', forms the "dub" of "lub-dub" and is composed of components A<sub>2</sub> and P<sub>2</sub>. It is caused by the sudden block of reversing blood flow due to closure of the [[aortic valve]] and [[pulmonary valve]] at the end of ventricular [[systole]], i.e beginning of ventricular [[diastole]]. As the [[left ventricle]] empties, its pressure falls below the pressure in the [[aorta]], aortic blood flow quickly reverses back toward the left ventricle, catching the aortic valve leaflets and is stopped by aortic (outlet) valve closure. Similarly, as the pressure in the [[right ventricle]] falls below the pressure in the [[pulmonary artery]], the pulmonary (outlet) valve closes. The '''S<sub>2</sub>''' sound results from reverberation within the blood associated with the sudden block of flow reversal. ====S<sub>2</sub> splitting==== During inspiration, the increased negative [[intrathoracic]] pressure which allows lung expansion also induces both increased blood return from the body into the right ventricle and simultaneous reduced blood volume return from the lungs into the left ventricle. Because of the increased blood volume in the right ventricle, the pulmonary valve stays open longer during ventricular systole whereas the aortic valve closes slightly earlier due to slightly reduced left ventricular volume. Thus the P<sub>2</sub> component of S<sub>2</sub> is delayed relative to the A<sub>2</sub> component. This delay in P<sub>2</sub> versus A<sub>2</sub> is heard as a slight broadening or even "splitting" of the second heart sound, though usually only in the pulmonic area of the chest because the P<sub>2</sub> is soft and not heard in other areas. During expiration, the less negative (than during inspiration) intrathoracic pressure no longer increases blood return to the right ventricle versus the left ventricle, the right ventricle volume in no longer increased, the pulmonary valve closes earlier, P<sub>2</sub> occurs earlier and overlaps A<sub>2</sub>. It is physiological to hear a "splitting" of the second heart tone in younger people, during inspiration and in the "pulmonary area", i.e. the 2nd ICS (intercostal space) at the left edge of the sternum. During expiration, the interval between the two components normally shortens and the S2 sounds become merged. A [[bundle branch block]] will produce continuous splitting but the degree of splitting will still vary with respiration. If splitting does not vary with inspiration, it is termed a "fixed split S2" and is usually due to an [[atrial septal defect]] (ASD) or [[ventricular septal defect]] (VSD). The ASD or VSD creates a left to right shunt that increases the blood flow to the right side of the heart, thereby causing the pulmonic valve to close later than the aortic valve independent of inspiration/expiration. Reverse splitting indicates pathology. Aortic stenosis, hypertrophic cardiomyopathy, left bundle branch block and a ventricular pacemaker could all cause a reverse splitting of the second heart sound. ==Extra heart sounds== The rarer extra heart sounds form [[gallop rhythm]]s and are heard in both normal and abnormal situations. ===S<sub>3</sub>=== {{Main|Third heart sound}} Rarely, there may be a [[third heart sound]] also called a '''protodiastolic gallop''', '''ventricular gallop''', or informally the "[[Kentucky]]" gallop as an [[onomatopoeia|onomatopoeic]] reference to the rhythm and stress of S1, S2, and S3 together (S1=ken; S2=tuc; S3=ky). It occurs at the beginning of diastole after S2 and is lower in pitch than S1 or S2 as it is not of valvular origin. The third heart sound is benign in youth and some trained athletes, but if it re-emerges later in life it may signal cardiac problems like a failing left ventricle as in dilated [[congestive heart failure]] (CHF). ===S<sub>4</sub>=== {{Main|Fourth heart sound}} The rare [[fourth heart sound]] is sometimes audible in healthy children and again in trained athletes, but when audible in an adult is called a '''presystolic gallop''' or '''atrial gallop'''. This gallop is produced by the sound of blood being forced into a stiff/hypertrophic ventricle. It is a sign of a pathologic state, usually a failing left ventricle. The sound occurs just after atrial contraction ("atrial kick") at the end of diastole and immediately before S1, producing a rhythm sometimes referred to as the "[[Tennessee]]" gallop where S4 represents the "tenn-" syllable. The combined presence of S3 and S4 is a '''quadruple gallop'''. At rapid heart rates, S3 and S4 may merge to produce a '''summation gallop'''. ==Murmurs== '''[[Heart murmur]]s''' are produced as a result of turbulent flow of blood, turbulence sufficient to produce audible noise. They are usually heard as a whooshing sound. The term murmur only refers to a sound believed to originate within blood flow through or near the heart; rapid blood velocity is necessary to produce a murmur. Though not fully reliable, soft murmurs are less likely to reflect a serious, if any, health problem; loud murmurs essentially always reflect a problem. Yet most heart problems do not produce any murmur and most valve problems also do not produce an audible murmur. The following paragraphs overview the murmurs most commonly heard in adults who do not have major congenital heart abnormalities. * [[Regurgitation_(circulation)|Regurgitation]] through the mitral valve is by far the most commonly heard murmur, sometimes fairly loud to a practiced ear, even though the volume of regurgitant blood flow may be quite small. Yet, though obvious using [[echocardiography]] visualization, probably about 20% of cases of mitral regurgitation do not produce an audible murmur. * [[Stenosis]] of the aortic valve is typically the next most common heart murmur, a systolic ejection murmur. This is more common in older adults or in those individuals having a two, not a three leaflet aortic valve. * Regurgitation through the aortic valve, if marked, is sometimes audible to a practiced ear with a high quality, especially electronically amplified, stethoscope. Generally, this is a very rarely heard murmur, even though aortic valve regurgitation is not so rare. Aortic regurgitation, though obvious using [[echocardiography]] visualization, usually does not produce an audible murmur. * Stenosis of the mitral valve, if severe, also rarely produces an audible, low frequency soft rumbling murmur, best recognized by a practiced ear using a high quality, especially electronically amplified, stethoscope. * Either regurgitation through, or stenosis of, the tricuspid or pulmonary valves essentially never produces audible murmurs. * Other audible murmurs are associated with abnormal openings between the left ventricle and right heart or from the aortic or pulmonary arteries back into a lower pressure heart chamber. {| class="wikitable" |- ! '''Gradations of Murmurs'''{{ref|Abnormal_sounds}} |- | '''Grade''' | '''Description''' |- | Grade 1 | Very faint, heard only after listener has "tuned in"; may not be heard in all positions. |- | Grade 2 | Quiet, but heard immediately after placing the stethoscope on the chest. |- | Grade 3 | Moderately loud. |- | Grade 4 | Loud, with palpable thrill (ie, a tremor or vibration felt on palpation)<ref>{{cite web|url=http://www2.merriam-webster.com/cgi-bin/mwmednlm?book=Medical&va=thrill|title=Medline Plus Medical Dictionary, definition of "cardiac thrill"}}</ref> |- | Grade 5 | Very loud, with thrill. May be heard when stethoscope is partly off the chest. |- | Grade 6 | Very loud, with thrill. May be heard with stethoscope entirely off the chest. |} As noted, several different [[heart|cardiac]] conditions can cause heart murmurs. However, the murmurs produced often change in complex ways with the severity of the cardiac disease. An astute physician can sometimes diagnose cardiac conditions with some accuracy based largely on the murmur, related physical examination and experience with the relative frequency of different heart conditions. However, with the advent of better quality and wider availability of [[echocardiography]] and other techniques, heart status can be recognized and quantified much more accurately than formerly possible with only a stethoscope, examination and experience. ===Effects of inhalation/expiration=== [[Inhalation]] pressure causes an increase in the venous blood return to the right side of the heart. Therefore, ''right-sided murmurs generally increase in intensity with inspiration''. The increased volume of blood entering the right sided chambers of the heart restricts the amount of blood entering the left sided chambers of the heart. This causes left-sided murmurs to generally decrease in intensity during inspiration. With [[exhalation|expiration]], the opposite haemodynamic changes occur. This means that left-sided murmurs generally increase in intensity with expiration. Having the patient lie supine and raising their legs up to a 45 degree angle facilitates an increase in venous return to the right side of the heart producing effects similar to inhalation-increased blood flow. ===Interventions that change murmurs=== {{Main|Heart murmur#Interventions that change murmur sounds}} There are a number of interventions that can be performed that alter the intensity and characteristics of abnormal heart sounds. These interventions can differentiate the different heart sounds to more effectively obtain a diagnosis of the cardiac anomaly that causes the heart sound. ==Other abnormal sounds== '''Clicks''': With the advent of newer, non-invasive imaging techniques, the origin of other, so-called ''[[adventitial]] sounds'' or "clicks" has been appreciated. These are short, high-pitched sounds. * The atrioventricular valves of patients with [[mitral stenosis]] may open with an ''opening snap'' on the beginning of [[diastole]]. * Patients with [[mitral valve prolapse]] may have a [[systole|mid-systolic]] click along with a murmur. * [[Aortic valve stenosis|Aortic]] and [[pulmonary stenosis]] may cause an ejection click immediately after S<sub>1</sub>. '''Rubs''': Patients with [[pericarditis]], an [[inflammation]] of the sac surrounding the heart ([[pericardium]]), may have an audible [[pericardial friction rub]]. This is a characteristic scratching, creaking, high-pitched sound emanating from the rubbing of both layers of inflammated pericardium. It is the loudest in systole, but can often be heard at the beginning and at the end of diastole. It is very dependent on body position and breathing, and changes from hour to hour. ==Surface anatomy== The aortic area, pulmonic area, tricuspid area and mitral area are areas on the surface of the chest where the heart is auscultated. The opening and closing of the valves is usually much less loud than the sound of the blood rushing through the valve and "colliding" with the subsequent barrier. Because of this, auscultation to determine function of a valve is usually not performed at the position of the valve, but at a downstream position where the listener can best hear the blood colliding after the valve is closed. {| class="wikitable" | [[Pulmonary valve]] (to [[pulmonary trunk]]) || second [[intercostal space]] || left upper sternal border |- | [[Aortic valve]] (to [[aorta]]) || second intercostal space || right upper sternal border |- | [[Mitral valve]] (to [[left ventricle]]) || fifth intercostal space || lateral to left midclavicular line |- | [[Tricuspid valve]] (to [[right ventricle]]) || fourth intercostal space || lower left sternal border |} ==Recording heart sounds== Using [[stethoscope|electronic stethoscopes]], it is possible to record heart sounds via direct output to an external recording device, such as a [[notebook computer|laptop]] or [[MP3]] recorder. The same connection can be used to listen to the previously-recorded [[auscultation]] through the stethoscope headphones, allowing for more detailed study of [[heart murmur|murmur]]s and other heart sounds, for general research as well as evaluation of a particular patient's condition. ==See also== * [[Pulse]] * [[Physical examination]] * [[Precordial examination]] * [[Heart murmur]] * [[Benign paediatric heart murmur]] * Pulsatile [[Tinnitus|Tinnitus]] - hearing a heartbeat sound in one or both ears == Notes and references == {{reflist}} == External links == * [http://www.med.umich.edu/lrc/coursepages/M1/anatomy/html/surface/thorax/hsounds.html Diagram, with associated sounds] at [[University of Michigan]] * [http://www.blaufuss.org/tutonline.html# Flash tutorials] at blaufuss.org * [http://www.dundee.ac.uk/medther/Cardiology/hsmur.html Overview] at [[University of Dundee]] * [http://depts.washington.edu/physdx/heart/demo.html Overview] at [[University of Washington]] * [http://www.med.ucla.edu/wilkes/intro.html Recorded heart sounds at Auscultation Assistant] at [[UCLA]] {{Cardiovascular physiology}} [[Category:Cardiology]] [[cs:Puls (tep)]] [[de:Herztöne]] [[id:Denyut jantung]] [[it:Soffio cardiaco]] [[pl:Tony serca]] [[pt:Sons cardíacos]] [[fi:Sydänääni]] [[sv:iktus]] [[zh:心音]]