Murmurs

Murmurs are auscultatory sounds heard within the heart chambers or major arteries. They’re classified by their timing and duration in the cardiac cycle, auscultatory location, loudness, configuration, pitch, and quality. (See Classifying murmurs.)

Murmurs can reflect accelerated blood flow through normal or abnormal valves; forward blood flow through a narrowed or irregular valve or into a dilated vessel; blood backflow through an incompetent valve, septal defect, or patent ductus arteriosus; or decreased blood viscosity. Commonly the result of organic heart disease, murmurs occasionally may signal an emergency situation — for example, a loud holosystolic murmur after an acute myocardial infarction (MI) may signal papillary muscle rupture or ventricular septal defect. Murmurs may also result from surgical implantation of a prosthetic valve.

Some murmurs are innocent, or functional. An innocent systolic murmur is generally soft, medium-pitched, and loudest along the left sternal border at the second or third intercostal space. It’s exacerbated by physical activity, excitement, fever, pregnancy, anemia, or thyrotoxicosis. (See Detecting common congenital murmurs, page 418.)

Emergency Actions

Although not usually a sign of an emergency, murmurs — especially newly developed ones — may signal a serious complication in patients with bacterial endocarditis or a recent acute MI. When caring for a patient with known or suspected bacterial endocarditis, carefully auscultate for any new murmurs. Their development along with crackles, distended jugular veins, orthopnea, and dyspnea may signal heart failure.

Regular auscultation is also important in a patient who has experienced an acute MI. A loud decrescendo holosystolic murmur at the apex that radiates to the axilla and left sternal border or throughout the chest is significant, particularly in association with a widely split S₂ and an atrial gallop (S₄). This murmur, when accompanied by signs of acute pulmonary edema, usually indicates the development of acute mitral insufficiency due to rupture of the chordae tendineae — a medical emergency.

History

If you discover a murmur, try to determine its type through careful auscultation. (See Identifying common murmurs.) Use the bell of your stethoscope for low-pitched murmurs; the diaphragm for high-pitched murmurs.

Next, obtain a patient history. Ask if the murmur is a new discovery or if it has been known since birth or childhood. Find out if the patient has experienced any associated symptoms, particularly palpitations, dizziness, syncope, chest pain, dyspnea, and fatigue. Explore the patient’s medical history, noting especially any incidence of rheumatic fever, recent dental work, heart disease, or heart surgery, particularly prosthetic valve replacement.

Physical assessment

Perform a systematic physical assessment. Note especially the presence of cardiac arrhythmias, jugular vein distention, and such pulmonary signs and symptoms as dyspnea, orthopnea, and crackles. Is the patient’s liver tender or palpable? Does he have peripheral edema?

Medical causes

Aortic insufficiency

Acute aortic insufficiency typically produces a soft, short diastolic murmur over the left sternal border that’s best heard when the patient sits and leans forward and at the end of a forced held expiration. S₂ may be soft or absent. Sometimes, a soft, short midsystolic murmur may also be heard over the second right intercostal space. Associated findings include tachycardia, dyspnea, jugular vein distention, crackles, increased fatigue, and pale, cool extremities.

Chronic aortic insufficiency causes a high-pitched, blowing, decrescendo diastolic murmur that’s best heard over the second or third right intercostal space or the left sternal border with the patient sitting, leaning forward, and holding his breath after deep expiration. An Austin Flint murmur — a rumbling, mid-to-late diastolic murmur best heard at the apex — may also occur. Findings include palpitations, tachycardia, angina, increased fatigue, dyspnea, orthopnea, and crackles.

Aortic stenosis

With aortic stenosis, the murmur is systolic, beginning after S₁ and ending at or before aortic valve closure. It’s harsh and grating, medium-pitched, and crescendo-decrescendo. Loudest over the second right intercostal space when the patient is sitting and leaning forward, this murmur may also be heard at the apex, at the suprasternal notch (Erb’s point), and over the carotid arteries.

If the patient has advanced disease, S₂ may be heard as a single sound, with inaudible aortic closure. An early systolic ejection click at the apex is typical but is absent when the valve is severely calcified. Associated signs and symptoms may include dizziness, syncope, dyspnea on exertion, paroxysmal nocturnal dyspnea, fatigue, and angina.

Cardiomyopathy (hypertrophic)

Hypertrophic cardiomyopathy generates a harsh late systolic murmur, ending at S₂. Best heard over the left sternal border and at the apex, the murmur is commonly accompanied by an audible S₃or S₄. The murmur decreases with squatting and increases with sitting down. Major associated symptoms are dyspnea and chest pain; palpitations, dizziness, and syncope may also occur.

Mitral insufficiency

Acute mitral insufficiency is characterized by a medium-pitched blowing, early systolic or holosystolic decrescendo murmur at the apex, along with a widely split S₂ and commonly an S₄. This murmur doesn’t get louder on inspiration as with tricuspid insufficiency. Associated findings typically include tachycardia and signs of acute pulmonary edema.

Chronic mitral insufficiency produces a high-pitched, blowing, holosystolic plateau murmur that’s loudest at the apex and usually radiates to the axilla or back. Fatigue, dyspnea, and palpitations may also occur.

Mitral prolapse

Mitral prolapse generates a midsystolic to late-systolic click with a high-pitched late-systolic crescendo murmur, best heard at the apex. Occasionally, multiple clicks may be heard, with or without a systolic murmur. Associated findings include cardiac awareness, migraine headaches, dizziness, weakness, syncope, palpitations, chest pain, dyspnea, severe episodic fatigue, mood swings, and anxiety.

Mitral stenosis

With mitral stenosis, the murmur is soft, low-pitched, rumbling, crescendo-decrescendo, and diastolic, accompanied by a loud S₁ or an opening snap — a cardinal sign. It’s best heard at the apex with the patient in the left lateral position. Mild exercise will help make this murmur audible.

With severe stenosis, the murmur of mitral insufficiency may also be heard. Other findings include hemoptysis, exertional dyspnea and fatigue, and signs of acute pulmonary edema.

Papillary muscle rupture

Papillary muscle rupture, a life-threatening complication of an acute MI, produces a loud holosystolic murmur that can be auscultated at the apex. Related findings include severe dyspnea, chest pain, syncope, hemoptysis, tachycardia, and hypotension.

Rheumatic fever with pericarditis

A pericardial friction rub along with murmurs and gallops is heard best with the patient leaning forward on his hands and knees during forced expiration. The most common murmurs heard in patients with rheumatic fever are the systolic murmur of mitral insufficiency, a midsystolic murmur due to swelling of the leaflet of the mitral valve, and the diastolic murmur of aortic insufficiency. Other signs and symptoms include fever, joint and sternal pain, edema, and tachypnea.

Tricuspid insufficiency

Tricuspid insufficiency is a valvular abnormality that’s characterized by a soft, high-pitched, holosystolic blowing murmur that increases with inspiration (Carvallo’s sign) and decreases with exhalation and Valsalva’s maneuver. This murmur is best heard over the lower left sternal border and the xiphoid area. Following a lengthy period without symptoms, exertional dyspnea and orthopnea may develop, along with jugular vein distention, ascites, peripheral cyanosis and edema, muscle wasting, fatigue, weakness, and syncope.

Tricuspid stenosis

Tricuspid stenosis is a valvular disorder that produces a diastolic murmur similar to that of mitral stenosis, but louder with inspiration and decreased with exhalation and Valsalva’s maneuver. S₁ may also be louder. Associated signs and symptoms include fatigue, syncope, peripheral edema, jugular vein distention, ascites, hepatomegaly, and dyspnea.

Other causes

Treatments

Prosthetic valve replacement may cause variable murmurs, depending on the location, valve composition, and method of operation.

Special considerations

Prepare the patient for diagnostic tests, such as electrocardiography, echocardiography, and angiography. Administer an antibiotic and an anticoagulant as appropriate.

Pediatric pointers

Innocent murmurs, such as Still’s murmur, are commonly heard in young children and typically disappear in puberty. Pathognomonic heart murmurs in infants and young children usually result from congenital heart disease, such as atrial and ventricular septal defects. Other murmurs can be acquired, as with rheumatic heart disease.

Patient counseling

Instruct the patient to contact his physician before undergoing invasive procedures or dental work because prophylactic antibiotics may be necessary. Because any cardiac abnormality is frightening to the patient, provide emotional support.

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Book Source Details

• Book Title: Signs & Symptoms: A 2-in-1 Reference for Nurses
• Author(s): Springhouse
• Year of Publication: 2007
• Copyright Details: Signs & Symptoms: A 2-in-1 Reference for Nurses, Copyright © 2007 Lippincott Williams & Wilkins.

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Copyright Details: Signs & Symptoms: A 2-in-1 Reference for Nurses, Copyright © 2008 Williams & Wilkins.

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More About This Book: Title: Signs & Symptoms: A 2-in-1 Reference for Nurses Authors: Springhouse Publisher: Lippincott Williams & Wilkins Copyright: 2007 ISBN: 1-58255-318-1

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