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StatPearls . Treasure Island also (FL): StatPearls Publishing; 2021 Jan-.


Physiology, Cardiovascular Murmurs

Seth L. Thomas; Joseph Heaton; Amgad N. Makaryus.

Author Information


Cardiac auscultation is a crucial physical exam tool for carriers. Comprehension of anatomy, physiology, and also underlying physics, through mastery of physical examination, have the right to uncover many potential pathologies and prevent major complications. In trained people, sensitivity and specificity for murmurs can reach 70% and also 98%, respectively<1>. Because beforehand detection of cardiac murmurs have the right to be important to reducing morbidity and mortality, healthcare service providers must grasp these murmurs and also their prevalent etiologies.


Murmurs of the cardiac mechanism develop because of alterations in blood flow or mechanical operation. Depfinishing on the cause, auscultation findings in pitch, volume, and rhythm may adjust. The advance of murmurs is extremely dependent on the etiology and also is not constantly linked with a pathologic process<2><3>; benign murmurs are widespread in youngsters and also in the time of pregnancy<4>.

Murmurs develop from a multitude of mechanisms. Typical instances include low blood viscosity from anemia, septal defects, faitempt of the ductus arteriosus to cshed in newborns, too much hydrostatic press on cardiac valves leading to valve faientice, hypertrophic obstructive cardiomyopathy, and valvular certain pathologies. Regardmuch less of underlying etiology, all involve the creation of disturbed blood flow, which produces a murmur<5>.

Related Testing


Murmurs are identifiable via auscultation utilizing a hand-operated or electronically magnified stethoscope<6><7><8>. Description of murmurs is made utilizing the adhering to criteria, defined below: area, high quality, and also timing<9>.


Aortic valve: second intercostal room at the ideal sternal border.
Pulmonary valve: second intercostal area at the left sternal border.
Tricuspid valve: fourth intercostal space at the left sternal border.
Mitral valve: fifth intercostal space at the left midclavicular line.
Radiation: Murmurs may radiate, enabling auscultation at remote locations

Quality: Intensity

Grade I: faint murmur, bacount audible
Grade II: soft murmur
Grade III: conveniently audible yet without a palpable thrill
Grade IV: easily audible murmur with a palpable thrill
Grade V: loud murmur, audible through stethoscope lightly emotional the chest
Grade VI: loudest murmur, audible through stethoscope not poignant the chest

Quality: Pitch

High or low frequency
Other descriptive terms: blowing, harsh, musical, rumbling, squeaky

Quality: Profile

Crescendo: a murmur which increases in intensity
Decrescendo: a murmur that decreases in intensity
Crescendo-decrescendo: a murmur that initially increases in intensity, peaks, and then decreases in intensity
Plateau: static intensity


Systolic: occurs at or after S1, finishing prior to or at S2
Diastolic: occurs at or after S2, finishing prior to or at S1
Can be described as early, mid, late
Other murmurs: systolic murmurs deserve to be holosystolic, throughout systole; consistent murmurs begin in systole and terminate after S2


Many murmurs will boost or decrease in volume when the patient perdevelops certain maneuvers. This dynamic top quality of murmurs is used as a clinical tool during the patient"s physical exam to aid in diagnosing a particular murmur<10><11><12>. Some examples of how maneuvers readjust the intensity of certain murmurs include:

Handgrip: Increases afterload. Hand gripping increases the stamina of aortic regurgitation, mitral regurgitation, and also ventricular septal defect murmurs. It decreases the intensity of murmurs due to hypertrophic obstructive cardiomyopathy and mitral valve prolapse.
Squatting: Increases preload. Squatting increases the intensity of aortic stenosis, mitral stenosis, aortic regurgitation, and mitral regurgitation. It decreases the stamina of murmurs as a result of hypertrophic obstructive cardiomyopathy and also mitral valve prolapse.
Valsalva: Decreases preload. Valsalva increases the toughness of murmurs due to hypertrophic obstructive cardiomyopathy and also mitral valve prolapse. It decreases the intensity of aortic stenosis, mitral stenosis, aortic regurgitation, mitral regurgitation, and also ventricular septal defects.
Standing abruptly: Decreases prepack and also has the same impacts as Valsalva. Sudden standing increases the intensity of murmurs in hypertrophic obstructive cardiomyopathy and also mitral valve prolapse. It decreases the strength of aortic stenosis, mitral stenosis, aortic regurgitation, mitral regurgitation, and ventricular septal defects.
Amyl nitrate: Decreases afterload. Amyl nitprice rises the intensity of aortic stenosis, hypertrophic obstructive cardiomyopathy, and mitral valve prolapse. It decreases the severity of aortic regurgitation, mitral regurgitation, and ventricular septal defects.


Symptomatic patients presenting via new murmurs are constantly investigated through imaging. An echocardiogram is preferred to evaluate cardiac framework and attribute bereason of its practicality, sensitivity, and also specificity for detecting valvular diseases. It likewise dynamically evaluates the heart, allowing for the diagnosis of disease otherwise unseen on nondynamic imaging. Echocardiography and a chest X-ray are recommended by a number of significant institutions such as the Amerihave the right to College of Cardiology, the Amerihave the right to Heart Association, and the European Society of Cardiology as the initially imaging studies to perdevelop to evaluate symptomatic murmurs.

Several types of echocardiography are accessible. The leastern invasive is trans-thoracic echocardiography. Trans-thoracic echocardiography permits for the precise diagnosis of valvular illness, embolism, endocarditis, and also aortic dissection. It is the most basic echocardiographic technique, but in some patients, imeras may be obstructed by the rib cage or excess tworry in obese patients. For these patients, one more even more invasive approach, trans-esophageal echocardiography, might be proper. Trans-esophageal echocardiography eliminates photo obstruction by visualizing the heart via a transducer presented into the esophagus.

Finally, cardiac catheterization have the right to be used for identifying pathologies. The catheter is offered to meacertain push and circulation in the heart, providing practical indevelopment to the provider. This is the the majority of invasive form of identification and thus is typically scheduled if various other modalities fail. 


Typical Murmurs and also the Cardiac Disease States

Murmurs have actually been carefully connected to a multitude of conditions throughout the centuries. There are several prevalent murmurs and cardiac illness claims from which each certain murmur creates.

Aortic stenosis

Aortic stenosis is brought about by narrowing the aortic valve and also is the many prevalent valvular pathology in the arisen people. Typically, the stenosis arises from senile calcification or a congenital anomaly, such as a bicuspid aortic valve. Less commonly, rheumatic heart condition can impact the aortic valve. The characteristic crescendo-decrescenexecute systolic murmur is auscultated at the right top sternal border and might radiate to the carotid arteries.

Aortic Regurgitation

Aortic regurgitation, likewise known as aortic insufficiency, is a decrescenperform blowing diastolic murmur heard finest at the left reduced sternal border, heard once blood flows retrograde into the left ventricle. This is the majority of commonly watched in aortic root dilation and also as sequelae of aortic stenosis.

Innocent or Flow Murmur

This type of murmur is normally mid-systolic, resulted in by boosted cardiac output. It is associated via no symptoms, generally watched in childhood and also pregnancy, and also resolves spontaneously. 

Pulmonary stenosis

Pulmonary stenosis is a systolic murmur best heard at the top left sternal border and also commonly connected with tetralogy of Fallot, carcinoid syndrome, congenital rubella syndrome, and Noonan syndrome.

Tricuspid stenosis

This diastolic murmur best heard at the reduced left sternal border. Usual causes incorporate infective endocarditis, viewed in intravenous drug individuals, and carcinoid syndrome. Prolonged tricuspid stenosis might lead to right atrial enlargement and also arrhythmias.

Tricuspid regurgitation

This type of murmur is systolic, auscultated at the lower left sternal border. It is likewise connected with intravenous drug individuals and also carcinoid syndrome.

Mitral stenosis

Mitral stenosis is a diastolic murmur, ideal heard at the left 5th midclavicular line. It is linked with infective endocarditis and also chronic rheumatic heart disease

Mitral regurgitation

Mitral regurgitation is a systolic murmur, ideal heard at the left 5th midclavicular line via possible radiation to the left axilla. It is commonly linked via infective endocarditis, rheumatic heart illness, congenital anomalies, and inferior wall myocardial infarctions.

Mitral valve prolapse

This murmur is auscultated as a very early systolic click, with a potential last systolic murmur. Prolapse is linked via chronic diseases of the valves and also congenital anomalies.

Pulmonic stenosis

Pulmonic stenosis is the major murmur auscultated in infants with Tetralogy of Fallot. It is explained as a crescendo-decrescencarry out systolic ejection murmur heard loudest at the upper left sternal border. Onset is commonly from congenital reasons but might be seen in chronic rheumatic heart condition.

Austin Flint murmur

This type of murmur is a mid-diastolic rumbling murmur heard ideal over the apex. It is speculated to happen due to an aortic regurgitant jet leading to the anterior mitral valve leaflet to close prematudepend. Austin Flint murmurs might be mistaken for mitral stenosis.

Atrial septal defect

This congenital defect is located in between the left and best atria, which allows blood to flow easily. Common auscultation reveals a loud and wide solved split S2 at the upper left sternal border. More substantial atrial septal defects are quieter, while little ones are louder and have actually a harsh top quality, as a result of much less turbulence via a larger, unrestricted conduit.

Ventricular septal defect

This murmur is holosystolic, best heard at the apex. Like atrial septum defects, smaller holes frequently current through louder and also harder murmurs.

Hypertrophic obstructive cardiomyopathy

Hypertrophic obstructive cardiomyopathy is an inherited myocardial illness in which the myocardium undergoes hypertrophic transforms. These transforms cause a systolic ejection murmur as a result of the mitral valve hitting the thickened septal wall throughout systole. The murmur is heard best in between the apex and the left sternal border. It becomes louder with any type of maneuver that decreases prepack or afterload, such as Valsalva or abrupt standing. This effect occurs because the reduced ventricular blood volume from lessened prefill or afterload allows for a closer approximation of the mitral valve to the hypertrophied septal wall, bring about even more unstable blood flow.

Patent ductus arteriosus

This distinctive machine-choose murmur is heard consistently at the left upper sternal border. Avoidance of NSAIDs is typical, as a result of possibly closing the life-sustaining conduit till assurance of correct cardiac feature is established.

Turners syndrome

This inherited condition regularly presents via a murmur in young woguys, the majority of commonly due to the existence of a bicuspid aortic valve or coarctation of the aorta. A bicuspid aortic valve will certainly existing as a systolic murmur best heard at the appropriate second intercostal room. Coarctation of the aorta will present in both systole and diastole and also is heard over the thoracic spine. The consistent harsh systolic component of the aorta"s coarctation is due to rough blood flowing with the aorta"s tiny diameter area. Its diastolic component is as a result of aortic regurgitation. Other reasons of murmurs in these patients incorporate hypoplastic left heart or aortic dissection.

Tetralogy of Fallot

The murmur in Tetralogy of Fallot will current in an infant and is normally due to pulmonic valve stenosis. Another possible source of murmur in these patients is from the ventricular septal defect. However before, this is less most likely bereason the ventricular septal defect is often huge in Tetralogy of Fallot patients. Pulmonic valve stenosis is identified as an early systolic click via a harsh systolic crescendo-decrescenexecute ejection murmur, best heard at the left top sternal border. Unfavor aortic stenosis, this murmur will certainly not radiate to the carotids.

Carcinoid syndrome

Carcinoid syndrome reasons thickening of the tricuspid and pulmonary valves, which leads to either stenosis or regurgitation murmurs from the valves. This thickening arises from high amounts of serotonin released from the carcinoid tumor after the tumor has metastasized to the liver.

Chronic rheumatic heart disease

Chronic rheumatic heart disease is a sequela of untreated streptococcal pharyngitis and acute rheumatic fever before. Autoimmune propelled damage occurs as a result of molecular mimicry between streptococcal M protein and the cardiac tissue.

Infective endocarditis

Infective endocarditis is linked with bacterial vegetative growths, a lot of commonly viewed on the tricuspid valve. This can result in tricuspid stenosis and tricuspid regurgitation.

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Prosthetic Valve Leaks

Murmurs may construct from a leak in any of the prostheses available for the four cardiac valves.