Systolic Murmur

Systolic Murmur: Excerpt from Field Guide to Bedside Diagnosis

Differential Overview

❑ Systolic ejection murmur

❑ Mitral regurgitation

❑ Mitral valve prolapse

❑ Aortic stenosis

❑ Aortic valve sclerosis

❑ Hypertrophic obstructive cardiomyopathy

❑ Atrial septal defect

❑ Pulmonic stenosis

❑ Tricuspid regurgitation

❑ Ventricular septal defect

❑ Aortic coarctation

Diagnostic Approach

The intensity of the murmur is proportional to the degree of stenosis until flow decreases markedly. Intensity can be expressed semiquantitatively, from grade 1/6, heard only with concentration, to grade 4/6, a loud murmur associated with a palpable thrill, to grade 6/6 with a thrill and murmur heard with the stethoscope off the chest. The duration of the murmur is proportional to the pressure differential between the two chambers.

An early systolic murmur, decrescendo at the apex, occurs in acute, severe mitral regurgitation (MR) with papillary muscle rupture, endocarditis, ruptured chordae tendineae, or blunt chest trauma. A midsystolic murmur is typical of aortic stenosis (AS). It can also be found with hypertrophic obstructive cardiomyopathy (HOC) and with hyperdynamic states. A late systolic murmur is usually heard with mitral valve prolapse (MVP) in association with a midsystolic click. A holosystolic murmur can be produced by severe MR or tricuspid regurgitation (TR), or by a ventricular septal defect (VSD), when the pressure differential between chambers persists throughout systole. Holosystolic murmurs are almost never innocent.

Handgrip decreases AS and HOC murmurs but increases MR, aortic regurgitation (AR), VSD, and mitral stenosis (MS). Transient arterial occlusion by a blood pressure cuff 20 mm above systolic increases left-sided murmurs. Valsalva decreases most murmurs (decreased right and left ventricular filling), except HOC and MVP, which increase.

Clinical Findings

Systolic ejection murmur  This is appreciated as a soft, pure, early or midsystolic murmur, heard best at the base without radiation, and decreased by Valsalva or standing. S₂ varies normally with respiration. In young adults, these originate in the pulmonary outflow tract. Physiologic murmurs caused by hyperdynamic blood flow may be heard with anemia, fever, pregnancy, and thyrotoxicosis.

Mitral regurgitation  There is a holosystolic murmur, often musical in quality. It is heard best at the apex and radiates to the axilla, although it can radiate to the neck if the regurgitant jet is directed toward the interatrial septum. The intensity varies little with respiration. Atrial fibrillation is often present also. In acute mitral regurgitation due to a papillary muscle rupture or endocarditis, there is an early systolic murmur because the atrium is normal sized and less distensible. The murmur is harsh, low-pitched, and grade 3/6 or louder. With a flail posterior leaflet, the murmur will radiate to the base, and with a flail anterior leaflet, to the axilla and back. Hypotension and acute pulmonary edema may be present.

Mitral valve prolapse  A midsystolic click is heard, accompanied by a late or holosystolic murmur over the apex without radiation. Maneuvers that decrease left ventricular volume move the click earlier. Those that increase volume increase the intensity of the murmur. Findings may vary from exam to exam.

Aortic stenosis  Typically, a loud, harsh, and low-pitched crescendo-decrescendo murmur is heard maximally at the upper right sternal border, and radiates into the carotids. As the severity of obstruction increases, the murmur peaks later in the cycle. At that point, the murmur is usually loud, and a thrill may be felt, corresponding to a peak gradient of 50 to 60 mm Hg. As flow decreases, the murmur may decrease in intensity. Other signs of hemodynamically significant obstruction include absence of A ₂ (S₂ is often obscured by the murmur) and a carotid impulse that has a weak, rounded rise rather than a brisk upstroke.

Aortic valve sclerosis  The acoustic signature is similar to mild aortic stenosis but with a normal S₂ and carotid impulse.

Hypertrophic obstructive cardiomyopathy  This is characterized by a midsystolic ejection murmur that changes in intensity with changes in left ventricular stroke volume. Maneuvers that decrease the volume, such as Valsalva and standing, increase the relative obstruction and the intensity of the murmur. The murmur is maximal at the apex and lower left sternal border and does not radiate well into the carotids. There may be a double or triple apical impulse with a thrill. A fourth heart sound is common. The carotid impulse may be brisk and bisferens.

Atrial septal defect  Widely fixed splitting of S₂ is characteristic, as is a pulmonic midsystolic murmur.

Pulmonic stenosis  A loud and long murmur, widely split or absent P₂, and an ejection click heard during expiration are diagnostic signs. In Tetralogy of Fallot, the murmur varies widely in intensity in relation to fluctuations in the volume of the veno-arterial shunt.

Tricuspid regurgitation  A soft, high-pitched holosystolic murmur is appreciated, maximal at the lower left sternal border and subxiphoid region. Large tricuspid waves may be seen in the jugular venous pulsations. If pulmonary hypertension is the cause, a pulmonary ejection click will often be audible, with the murmur increasing with inspiration (Carvello sign). Severe tricuspid regurgitation is associated with a right ventricular S₃, jaundice, an enlarged pulsatile liver with positive abdominojugular reflux, pulsatile ear lobes, edema, ascites, a right ventricular heave at the right lower sternal border, and prominent v waves.

Ventricular septal defect  The murmur is high-pitched, holosystolic, usually grade 3/6 or louder, and maximal over the mid-left sternal border but heard widely over the precordium. A thrill and third heart sound are often present as is a delayed P₂. If pulmonary hypertension produces reversal of shunting (Eisenmenger physiology), the murmur becomes early peaking, associated with a loud P₂, a pulmonary ejection click, an early diastolic Graham Steel murmur, and a right-sided Austin Flint murmur.

Aortic coarctation  A late systolic murmur heard in the back medial to the left scapula is associated with a blood pressure decrement in the legs.

Pictures

Book Source Details

• Book Title: Field Guide to Bedside Diagnosis
• Author(s): David S. Smith
• Year of Publication: 2007
• Copyright Details: Field Guide to Bedside Diagnosis, Copyright © 2007 Lippincott Williams & Wilkins.

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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.

More About This Book: Title: Field Guide to Bedside Diagnosis Authors: David S. Smith Publisher: Lippincott Williams & Wilkins Copyright: 2007 ISBN: 0-78178-165-5

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