Healiocom (2017) Heart Murmurs Topic Review Retreved From

Introduction

Cardiac auscultation is an essential physical exam tool for providers. Comprehension of beefcake, physiology, and underlying physics, with mastery of physical examination, can uncover many potential pathologies and foreclose serious complications. In trained individuals, sensitivity and specificity for murmurs tin reach 70% and 98%, respectively[1]. Since early detection of cardiac murmurs can be essential to reducing morbidity and bloodshed, healthcare providers should main these murmurs and their common etiologies.

Development

Murmurs of the cardiac system develop due to alterations in blood flow or mechanical performance. Depending on the cause, auscultation findings in pitch, volume, and rhythm may alter. The development of murmurs is highly dependent on the etiology and is not e'er associated with a pathologic process[ii][three]; benign murmurs are common in children and during pregnancy[4].

Murmurs develop from a multitude of mechanisms. Typical cases include low blood viscosity from anemia, septal defects, failure of the ductus arteriosus to close in newborns, excessive hydrostatic pressure on cardiac valves causing valve failure, hypertrophic obstructive cardiomyopathy, and valvular specific pathologies. Regardless of underlying etiology, all involve the creation of disturbed claret flow, which produces a murmur[5].

Related Testing

Auscultation

Murmurs are identifiable through auscultation using a manual or electronically enhanced stethoscope[6][7][8]. Clarification of murmurs is made using the following criteria, explained below: location, quality, and timing[9].

Location

• Aortic valve: 2nd intercostal space at the correct sternal border.

• Pulmonary valve: second intercostal infinite at the left sternal border.

• Tricuspid valve: quaternary intercostal infinite at the left sternal edge.

• Mitral valve: fifth intercostal space at the left midclavicular line.

• Radiation: Murmurs may radiate, allowing auscultation at remote locations

Quality: Intensity

• Grade I: faint murmur, barely audible

• Grade Two: soft murmur

• Class III: easily audible but without a palpable thrill

• Grade IV: easily audible murmur with a palpable thrill

• Grade V: loud murmur, audible with stethoscope lightly touching the chest

• Grade Half dozen: loudest murmur, audible with stethoscope not touching the chest

Quality: Pitch

• High or low frequency

• Other descriptive terms: bravado, 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

Timing

• Systolic: occurs at or afterward S1, finishing before or at S2

• Diastolic: occurs at or after S2, finishing earlier or at S1

• Can be described equally early, mid, late

• Other murmurs: systolic murmurs can exist holosystolic, throughout systole; continuous murmurs brainstorm in systole and cease afterward S2

Maneuvers

Near murmurs will increment or decrease in volume when the patient performs certain maneuvers. This dynamic quality of murmurs is used as a clinical tool during the patient's physical exam to aid in diagnosing a specific murmur[10][xi][12]. Some examples of how maneuvers change the intensity of particular murmurs include:

• Handgrip: Increases afterload. Paw gripping increases the forcefulness of aortic regurgitation, mitral regurgitation, and 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 strength of murmurs due to hypertrophic obstructive cardiomyopathy and mitral valve prolapse.

• Valsalva: Decreases preload. Valsalva increases the strength of murmurs due to hypertrophic obstructive cardiomyopathy and mitral valve prolapse. It decreases the intensity of aortic stenosis, mitral stenosis, aortic regurgitation, mitral regurgitation, and ventricular septal defects.

• Standing abruptly: Decreases preload and has the same effects as Valsalva. Sudden standing increases the intensity of murmurs in hypertrophic obstructive cardiomyopathy and mitral valve prolapse. It decreases the force of aortic stenosis, mitral stenosis, aortic regurgitation, mitral regurgitation, and ventricular septal defects.

• Amyl nitrate: Decreases afterload. Amyl nitrate increases 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.

Imaging

Symptomatic patients presenting with new murmurs are ever investigated with imaging. An echocardiogram is preferred to evaluate cardiac structure and function because of its practicality, sensitivity, and specificity for detecting valvular diseases. It besides dynamically evaluates the centre, allowing for the diagnosis of disease otherwise unseen on nondynamic imaging. Echocardiography and a chest X-ray are recommended by several major organizations such as the American College of Cardiology, the American Heart Clan, and the European Society of Cardiology as the first imaging studies to perform to evaluate symptomatic murmurs.

Several types of echocardiography are available. The least invasive is trans-thoracic echocardiography. Trans-thoracic echocardiography allows for the accurate diagnosis of valvular diseases, embolism, endocarditis, and aortic dissection. Information technology is the simplest echocardiographic method, just in some patients, images may be obstructed by the rib muzzle or backlog tissue in obese patients. For these patients, another more than invasive technique, trans-esophageal echocardiography, may be advisable. Trans-esophageal echocardiography eliminates epitome obstruction by visualizing the heart via a transducer introduced into the esophagus.

Finally, cardiac catheterization can be utilized for identifying pathologies. The catheter is used to measure out force per unit area and flow in the heart, providing valuable information to the provider. This is the nearly invasive grade of identification and thus is typically reserved if other modalities fail.

Pathophysiology

Common Murmurs and the Cardiac Affliction States

Murmurs have been closely linked to a multitude of diseases throughout the centuries. There are several common murmurs and cardiac illness states from which each specific murmur develops.

Aortic stenosis

Aortic stenosis is caused by narrowing the aortic valve and is the most common valvular pathology in the developed world. Typically, the stenosis arises from senile calcification or a congenital anomaly, such every bit a bicuspid aortic valve. Less ordinarily, rheumatic eye disease can touch on the aortic valve. The characteristic crescendo-decrescendo systolic murmur is auscultated at the right upper sternal border and may radiate to the carotid arteries.

Aortic Regurgitation

Aortic regurgitation, too known as aortic insufficiency, is a decrescendo blowing diastolic murmur heard best at the left lower sternal edge, heard when blood flows retrograde into the left ventricle. This is nigh commonly seen in aortic root dilation and equally sequelae of aortic stenosis.

Innocent or Menstruum Murmur

This type of murmur is usually mid-systolic, acquired by increased cardiac output. Information technology is associated with no symptoms, typically seen in babyhood and pregnancy, and resolves spontaneously.

Pulmonary stenosis

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

Tricuspid stenosis

This diastolic murmur best heard at the lower left sternal border. Typical causes include infective endocarditis, seen in intravenous drug users, and carcinoid syndrome. Prolonged tricuspid stenosis may lead to right atrial enlargement and arrhythmias.

Tricuspid regurgitation

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

Mitral stenosis

Mitral stenosis is a diastolic murmur, best heard at the left fifth midclavicular line. It is associated with infective endocarditis and chronic rheumatic middle disease

Mitral regurgitation

Mitral regurgitation is a systolic murmur, all-time heard at the left 5th midclavicular line with possible radiation to the left axilla. It is commonly associated with infective endocarditis, rheumatic heart disease, congenital anomalies, and inferior wall myocardial infarctions.

Mitral valve prolapse

This murmur is auscultated as an early systolic click, with a potential last systolic murmur. Prolapse is associated with chronic diseases of the valves and congenital anomalies.

Pulmonic stenosis

Pulmonic stenosis is the main murmur auscultated in infants with Tetralogy of Fallot. It is described as a crescendo-decrescendo systolic ejection murmur heard loudest at the upper left sternal border. Onset is typically from built causes but may be seen in chronic rheumatic heart disease.

Austin Flint murmur

This type of murmur is a mid-diastolic rumbling murmur heard best over the apex. It is speculated to occur due to an aortic regurgitant jet causing the anterior mitral valve leaflet to shut prematurely. Austin Flintstone murmurs may be mistaken for mitral stenosis.

Atrial septal defect

This congenital defect is located between the left and correct atria, which allows claret to flow freely. Typical auscultation reveals a loud and wide fixed split S2 at the upper left sternal border. More than substantial atrial septal defects are quieter, while small-scale ones are louder and have a harsh quality, due to less turbulence through a larger, unrestricted conduit.

Ventricular septal defect

This murmur is holosystolic, best heard at the apex. Like atrial septum defects, smaller holes typically present with louder and harder murmurs.

Hypertrophic obstructive cardiomyopathy

Hypertrophic obstructive cardiomyopathy is an inherited myocardial disease in which the myocardium undergoes hypertrophic changes. These changes cause a systolic ejection murmur due to the mitral valve hitting the thickened septal wall during systole. The murmur is heard all-time between the apex and the left sternal border. It becomes louder with whatever maneuver that decreases preload or afterload, such as Valsalva or abrupt standing. This effect occurs because the lower ventricular blood book from reduced preload or afterload allows for a closer approximation of the mitral valve to the hypertrophied septal wall, causing more turbulent blood flow.

Patent ductus arteriosus

This singled-out auto-similar murmur is heard continuously at the left upper sternal border. Avoidance of NSAIDs is standard, due to potentially closing the life-sustaining conduit until balls of proper cardiac function is established.

Turners syndrome

This inherited disease often presents with a murmur in young women, most normally due to the presence of a bicuspid aortic valve or coarctation of the aorta. A bicuspid aortic valve volition present every bit a systolic murmur best heard at the right second intercostal space. Coarctation of the aorta volition present in both systole and diastole and is heard over the thoracic spine. The continuous harsh systolic component of the aorta's coarctation is due to turbulent blood flowing through the aorta's small-scale diameter section. Its diastolic component is due to aortic regurgitation. Other causes of murmurs in these patients include hypoplastic left heart or aortic autopsy.

Tetralogy of Fallot

The murmur in Tetralogy of Fallot volition present in an infant and is ordinarily due to pulmonic valve stenosis. Another possible source of murmur in these patients is from the ventricular septal defect. However, this is less likely considering the ventricular septal defect is often big in Tetralogy of Fallot patients. Pulmonic valve stenosis is characterized as an early systolic click with a harsh systolic crescendo-decrescendo ejection murmur, best heard at the left upper sternal border. Unlike aortic stenosis, this murmur will non radiate to the carotids.

Carcinoid syndrome

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

Chronic rheumatic heart illness

Chronic rheumatic heart affliction is a sequela of untreated streptococcal pharyngitis and acute rheumatic fever. Autoimmune driven devastation occurs as a result of molecular mimicry between streptococcal M protein and the cardiac tissue.

Infective endocarditis

Infective endocarditis is associated with bacterial vegetative growths, virtually ordinarily seen on the tricuspid valve. This can lead to tricuspid stenosis and tricuspid regurgitation.

Prosthetic Valve Leaks

Murmurs may develop from a leak in whatsoever of the prostheses available for the four cardiac valves.

Clinical Significance

When combined with an accurately identified murmur, a patient history can provide critical details that pb to diagnosis[xiii]. Intravenous drug use, a history of untreated streptococcal pharyngitis or scarlet fever, valve replacement history, and a family history of cardiovascular illness or genetic disease are of import historical items to exist aware of in a patient with a murmur[xiv].

In addition to patient history, obtaining a detailed cardiovascular physical examination is paramount in identifying a murmur and its associated illness[15]. Brainstorm by auscultating the four cardiac listening posts to determine the cardiac murmur's location and allow for its characterization[16]. Murmurs are described using the thoracic cage position where they are auscultated, pitch, volume, and in which stage of the cardiac bicycle they occur. Auscultating other locations such every bit the axilla and carotid arteries also help accurately diagnose the murmur. It should be performed on any patient with a suspicion of a murmur. More severe murmurs are associated with thrills, which are palpable vibrations. Murmurs are graded in intensity from 1 to 6 using the Levine grading scale.

Murmurs are disquisitional physical examination findings in many patients. Many diseases take associated murmurs[9]. Fortunately, each murmur often has enough distinguishing qualities that, when combined with patient history, allows the medico to create a curtailed list of possible diagnoses. Imaging such every bit an echocardiogram is essential for a definitive diagnosis of any underlying cardiac disease.

The skill of accurately describing a murmur is only equally important as gathering a patient's history. For example, the ability to accurately study whether a murmur is heard in systole or diastole in a healthy-appearing kid is essential. The difference will determine whether or not to refer the patient to a pediatric cardiologist for further evaluation.

Review Questions

Figure

Aortic Regurgitation. Contributed past Katherine Humphreys

Figure

Aortic Stenosis. Contributed past Katherine Humphreys

Figure

Mitral Regurgitation. Contributed by Katherine Humphreys

Figure

Pulmonary Regurgitation. Contributed past Katherine Humphreys

Effigy

Pulmonic Stenosis. Contributed past Katherine Humphreys

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Source: https://www.ncbi.nlm.nih.gov/books/NBK525958/

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