Download Innocent Murmur

HISTORY
18-year-old black man.
CHIEF COMPLAINT: Evaluation of murmur.
PRESENT ILLNESS:
The murmur was noted on routine pre-college
physical examination. The patient is an asymptomatic All-State halfback. He
vaguely recalls a murmur having been noted in the past. His history is
otherwise entirely negative.
Question:
Is a specific diagnosis suggested by this history?
22-1
Answer:
No. While the patient’s murmur may be significant, the negative
history suggests the murmur could be innocent.
PHYSICAL SIGNS
a. GENERAL APPEARANCE - Normal muscular 18-year-old black man.
b. VENOUS PULSE - The CVP is estimated to be 3 cm H2O.
UPPER RIGHT STERNAL EDGE
JUGULAR VENOUS PULSE
Question:
How do you interpret the venous pulse?
22-2
Answer:
The venous pulse is normal in mean pressure and wave form,
showing a dominant “a” wave preceding the first heart sound followed by the “x”
descent, “v” wave, and “y” descent.
c. ARTERIAL PULSE - (BP = 110/70 mm Hg)
S1
S2
UPPER RIGHT
STERNAL EDGE
CAROTID
ECG
Question:
How do you interpret the carotid arterial pulse?
22-3
Answer:
The arterial pulse is normal in upstroke, peak, and downstroke.
d. PRECORDIAL MOVEMENT
PHONO
UPPER RIGHT
STERNAL EDGE
S1
S2
APEXCARDIOGRAM
Question:
How do you interpret the patient’s precordial movement?
22-4
Answer:
There is a normal brief apical impulse at the 5th intercostal space
in the midclavicular line.
e. CARDIAC AUSCULTATION
ECG
1
2
1
1
2L
A2 P2
EXPIRATION
0.1
sec
A2 P2
INSPIRATION
Question:
What is your interpretation of the acoustic events at the upper
left sternal edge?
22-5
Answer:
There is normal inspiratory splitting of the second heart sound. In
addition, a short, early, systolic, crescendo-decrescendo murmur is present.
Since the murmur is in early systole when the majority of blood leaves the
ventricles, it is likely related to turbulence of flow alone, and less likely related
to a significant degree of obstruction of the outflow tract. It is likely generated
over the pulmonary valve and artery, as it is best heard at the upper left sternal
edge. Note also the absence of an ejection sound.
e. CARDIAC AUSCULTATION (continued)
LOWER LEFT
STERNAL EDGE
Question:
How do you interpret the acoustic events at the lower left
sternal edge?
22-6
Answer:
There is normal splitting of the first sound due to mitral and
tricuspid closure respectively.
e. CARDIAC AUSCULTATION (continued)
S1
S2
S1
S2
APEX
.16 SECONDS
ECG
Question:
How do you interpret the heart sound marked by the arrow?
22-7
Answer:
The arrow marks the third heart sound (S3). In a young adult
patient such as this one it may be heard normally, i.e., whether an S3 is
abnormal or not is judged by the context in which it occurs (by “the company it
keeps”).
f.
PULMONARY AUSCULTATION
Question:
How do you interpret the acoustic events in the pulmonary lung fields?
Proceed
22-8
Answer:
In all lung fields, there are normal vesicular breath sounds.
ELECTROCARDIOGRAM
I
II
III
aVR
aVL
aVF
V1
V2
V3
V4
V5
V6
Question:
How do you interpret this ECG?
22-9
Answer:
The ECG is normal. Note there is slight “J” point elevation (early
repolarization) in several leads, which is a common variant.
CHEST X RAYS
RA
= Right Atrium
AA
SVC = Superior Vena Cava
AA
= Aortic Arch
PA
= Pulmonary Artery
S
V
C
PA
LAA = Left Atrial Appendage
LV
= Left Ventricle
C
= Greatest Cardiac Dimension
T
= Greatest Thoracic Dimension
(C/T = Cardiothoracic Ratio)
LAA
RA
C
LV
T
Question:
What is your
interpretation of this PA chest
X ray?
POSTEROANTERIOR (PA)
22-10
Answer:
The PA chest X ray is normal. The structures forming the heart’s
borders in this and the following views are labeled. When hemodynamically
significant lesions are present, these structures may be selectively enlarged.
Note also the cardiothoracic ratio is normal (<50%).
CHEST X RAYS
(continued)
RV = Right Ventricle
LA = Left Atrium
RV
LA
LV = Left Ventricle
LV
Question:
What is your interpretation
of this left lateral chest X ray?
LEFT LATERAL
22-11
Answer:
The lateral chest X ray is normal. When the left atrium is enlarged,
it displaces the barium-filled esophagus posteriorly. When the right ventricle is
enlarged, it may obscure the substernal space.
Proceed
22-12
The history, physical examination, ECG and chest X rays are all normal. The
only question raised is the significance of the murmur, and it is typical of an
“innocent” murmur. In addition, the second heart sound is normal and there is
no ejection sound.
Because the bedside examination alone has defined the murmur as “innocent,”
no further evaluation is indicated.
Question: What is the hemodynamic explanation for this patient’s murmur?
22-13
Answer:
The murmur occurs in early systole due to turbulence in the
pulmonary artery associated with rapid flow during the early ejection period of
the right ventricle (2/3 of the stroke volume leaves the ventricle during the first
1/3 of systole). It is commonly heard in the young patient whose circulation is
dynamic. It may be less prominent when the patient is erect due to a decrease
in venous return. It is best heard over the pulmonary outflow tract which lies
just below the chest wall at the upper left sternal edge.
Question:
What organic cardiac lesions should have been considered in
this patient?
22-14
Answer:
An atrial septal defect causes a similar systolic murmur, but one
would expect wide fixed splitting of the second heart sound and a mid-diastolic
murmur at the lower left sternal edge. Mild valvular pulmonary stenosis also
may have a similar murmur but a pulmonary ejection sound usually is present
following the first sound.
Other diagnostic considerations include idiopathic dilatation of the pulmonary
artery and subvalvular aortic stenosis. The lack of any support for an organic
lesion on complete non-invasive bedside examination is the main reason to
conclude that this patient’s murmur is innocent, i.e., the murmur is judged by
“the company it keeps,” and in this case, it is all normal.
Question:
What other types of innocent systolic murmurs may be
heard in youth?
22-15
Answer:
a. The vibratory systolic (Still’s) murmur. This is most often heard in young
children between the lower left sternal edge and apex. It is early systolic
and has a buzzing quality. It is thought to be due to vibrations emanating
from normal structures in one or both ventricles. A tracing from a healthy
5-year-old is shown below.
LOWER LEFT
STERNAL EDGE
VIBRATORY
MURMUR
S1
S2
ECG
Proceed
22-16
Answer (continued):
b. The supraclavicular murmur. This murmur is also heard in children in early
systole, and is often bilateral. It likely originates in the brachiocephalic
arteries. Posterior movement of the shoulders may result in a decrease in
the murmur.
Question:
Are there other “innocent” murmurs that can be heard in the
adult?
Proceed
22-17
Answer:
In the past, the “aortic sclerotic” murmur was considered an
“innocent” murmur of the elderly. It is associated, however, with an increased
risk of atherosclerotic heart disease. It is best heard at the upper right sternal
edge and is early to midsystolic. It is likely caused by slight fibrosis of the
cusps and dilatation of the aortic root that occur with age. The murmur results
from turbulence of blood in the aortic root during maximum ejection from the left
ventricle. A typical phonocardiogram from a 65-year-old man is shown below.
“AORTIC SCLEROTIC”
MURMUR
UPPER RIGHT
STERNAL EDGE
S1
A2
CAROTID
ECG
Question:
Are there innocent murmurs that are not systolic?
22-18
Answer:
Yes. Two continuous innocent murmurs may be heard.
a. The venous hum - This murmur may be heard in most children in the
supraclavicular fossa, especially on the right. It is enhanced by head
maneuvers and obliterated by pressure on the internal jugular vein as
shown in the tracing below taken on a normal 10-year-old. It is due to the
dynamic venous circulation in youth. For the same reason, it may be heard
in anemic and thyrotoxic adults.
PRESSURE
b. The mammary souffle may be heard in the parasternal areas in lactating
females and is likely due to turbulence in arterial vessels supplying
the breasts.
Proceed
22-19
While no further evaluation is indicated, a diagrammatic illustration relating
intracardiac pressure and flow to the acoustic events found in this patient
follows, and explains the reason for the common systolic murmur occurring in
early systole with a crescendo-decrescendo configuration.
Proceed
22-20
LABORATORY
PRESSURE (mm Hg)
ECG
PAp
Pulmonary Artery Pressure (PAp)
a
v
Right Atrial Pressure (RAp)
Right Ventricular Pressure (RVp)
RAp
RVp
SYSTOLE
PHONOCARDIOGRAM
(UPPER LEFT STERNAL EDGE)
S1 A-V VALVE CLOSURE
S2 SEMILUNAR VALVE CLOSURE
S1
S2
Proceed
22-21
LABORATORY (continued)
PHONOCARDIOGRAM
(UPPER LEFT STERNAL EDGE)
SYSTOLE
VOLUME (cc.)
S1
S1 A-V VALVE CLOSURE
S2 SEMILUNAR VALVE CLOSURE
S2
RVv
RIGHT VENTRICULAR VOLUME (RVv)
A - First 1/3 systole
- 2/3 of blood ejected
A
B
B - Last 2/3 of systole
- 1/3 of blood ejected
Proceed for Summary
22-22
SUMMARY
The judgement that this patient’s murmur is innocent is based on an orderly
approach to bedside diagnosis. The murmur is innocent because of its
specific characteristics, but also because of the “company it keeps” on
bedside examination.
Proceed
22-23
To Review This Patient with a
Classic Innocent Murmur:
The HISTORY is negative.
PHYSICAL SIGNS:
a. The GENERAL APPEARANCE is that of a healthy, normal young man.
b. The JUGULAR VENOUS PULSE mean venous pressure is normal at
3 cm H2O. The wave form is normal with a dominant “a” wave due to atrial
contraction.
c. The CAROTID VESSEL is normal in upstroke, peak, and downstroke.
d. PRECORDIAL MOVEMENT reveals a normal brief apical impulse in the
fifth intercostal space at the midclavicular line, occurring at the time of the
first heart sound.
Proceed
22-24
e. CARDIAC AUSCULTATION reveals normal splitting of the first sound at
the lower left sternal edge of .03 seconds. There is normal inspiratory
splitting of the second heart sound at the upper left sternal edge of .06
seconds. An innocent (functional) murmur is heard at the upper left sternal
edge in early systole during maximal flow from the right ventricle, and is due
to turbulence in the pulmonary artery. A physiologic third sound is heard at
the apex. The murmur and third sound are judged as normal by the fact that
the remainder of the examination is negative.
f. PULMONARY AUSCULTATION reveals normal vesicular breath sounds
in all lung fields.
The ELECTROCARDIOGRAM shows early repolarization, a
normal variant.
The CHEST
X RAYS
are normal.
No LABORATORY work is necessary.
TREATMENT is reassurance.
22-25