The
Fourth Heart Sound-A Premature Requiem?
Additional Indexing Words:
Apex cardiogram
Phonocardiogram
of the heart, most are produced within the left
heart, and therefore, these are clinically the most
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FOR MANY years, clinicians have considered an
audible fourth heart sound as an abnormal
event indicative of cardiac disease, regardless of the
patient's age. Recently however, certain authors'
have suggested that fourth heart sounds can be
heard and recorded in the vast majority of normal
elderly individuals, aged 50 to 80 years. Of 196
ambulatory individuals in this age category, 143
(73%) had fourth heart sounds recorded by
phonocardiograms. They noted that the presence or
absence of a fourth heart sound was not related to
the presence or absence of cardiovascular disease.
Moreover, these authors found that of 88 patients in
whom phonocardiograms demonstrated fourth
heart sounds, 63 could be heard at the bedside. The
authors, therefore, concluded that the finding of an
audible fourth heart sound in the elderly age group
was a "normal" phenomenon equivalent to the
normal third heart sound of children and young
adults. They state further that the fourth heart
sound gallop may in fact be analogous to a third
heart sound gallop in the sense that it too may
represent the pathologic amplification of an otherwise normal event. To make matters even worse for
the clinician, they noted frequent observer disagreement, with the illusion that fourth heart
sounds were often present when in fact none were
found in graphic recordings. If these studies are
corroborated, then the presence of a fourth heart
sound in an elederly individual is a virtually
meaningless finding. Unfortunately, it is in this aged
population that the finding of a fourth heart sound
provides particularly useful information in the
diagnosis of such conditions as arteriosclerotic heart
disease and left ventricular hypertrophy.
Before we discard the fourth heart sound as a
useful clinical sign, we must first explore its
mechanism of production and certain older observations concerning its clinical correlates. Although
fourth heart sounds may originate from either side
important. It is of interest that Potain,2 who
described the presystolic (fourth) heart sound in
hypertension, also noticed an accompanying presystolic apical thrust over the precordium. Since then
numerous clinicians have recognized that the fourth
heart sound is closely associated with and synchronous with a brisk outward movement palpable over
the precordium at the time of a vigorous atrial
contraction3-6 (fig. 1). This brisk outward movement reflects left ventricular motion in response to a
vigorous left atrial contraction, and provides one of
the many bits of evidence which has led to the
universal conclusion that the major (audible)
vibrations of the fourth heart sound emanate from
within the ventricle itself. Normally, in the resting
individual this A wave does not exceed 15% of the
total apical excursion. It is my experience and that
of others4 that a fourth heart sound is unlikely to be
audible if the A wave of the apex tracing is not
accentuated. Moreover, the enlarged apical A wave
is often easier to palpate than is the fourth heart
sound to hear.4 Small apical A waves are seen
normally, and although they are usually accompanied by small recorded fourth heart sounds, these
waves are neither palpable nor are the associated
fourth heart sounds ordinarily audible (fig. 2).
Fourth heart sounds, therefore, may be recorded
phonocardiographically in many normal individuals, but they are usually small and not associated
with enlarged apical A waves. It is of considerable
interest that this presystolic pulsation only becomes
palpable when it falls into this abnormally large
range.4 Conversely, it is uncommon for an enlarged
A wave to be present but impalpable: examples of
this are provided when the P-R interval is quite
short or when the thoracic wall is abnormal or
obese. Physiologically, the presence of such an
enlarged presystolic wave indicates that the left
ventricle has a reduced distensibility and that the A
wave ("atrial kick") in the left ventricular pressure
tracing will also be enlarged with an elevated left
ventricular end-diastolic pressure. If the A wave
reaches 20% or more of the total vertical height of
the apexcardiogram, left ventricular end-diastolic
From the Department of Medicine, Indiana University at
Indianapolis, Indianapolis, Indiana.
Address for reprints: Morton E. Tavel, M.D., Indiana
University-Purdue at Indianapolis, University Quarter, 1100
West Michigan Street, Indianapolis, Indiana 46202.
4
Circulation, Volume XLIX, January 1974
EDITORIALS
5
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Figure 2
i
.Figure 1
Sound and pulse recording from a 62-year-old woman with
ischemic heart disease (previous myocardial infarction). At
the time of the fourth heart sound (4), the apexcardiogram
demonstrates a large, peaked presystolic A wave, which was
readily palpable. This wave measured 23% of the over-all
height of the complex.
pressure will invariably be more than 20 mm
Hg.4' 6, 8 In conclusion then, regardless of what one
hears, the presence of an enlarged apical A wave
indicates that a hemodynamic abnormality usually
associated with fourth sounds is present.
Inasmuch as an enlarged apical A wave bears the
same hemodynamic significance as an abnormal
fourth heart sound (atrial gallop), and may well be
a more reliably detected physical finding, it is
important to ascertain whether or not these waves
become more accentuated with the aging process.
Numerous studies of abnormal and normal apexcardiograms have indicated that the normal A wave
does not exceed 15% of the over-all height of the
recorded complex and that aging does not significantly alter this relationship."-"
What can we say about audibility of the fourth
heart sound? Rectra et al.' have shown that
Circulation, Volume XLIX, January 1974
Sound and pulse tracing from a 58-year-old man without
significant cardiovascular disease. In this case, the apical
A wave is within the normal range in height (14% of total
complex), and was not palpable. The corresponding fourth
sound, although recorded, was not audible.
auscultation alone is an inaccurate means to
ascertain the presence of a fourth heart sound. My
own experience also tends to agree with this
observation, and for a very good reason: the fourth
heart sound lies in a frequency range of about 20-30
Hz, an area in which human hearing is notoriously
insensitive. For this reason, it is likely that, unless
these sounds are quite loud, they are apt to be
missed completely. The apparently high incidence
with which fourth heart sounds are falsely thought
to be heard might be attributable to physiologic
splitting of the first heart sound or the first sound
followed by an ejection click. Notwithstanding
Spodick's statement12 to the contrary, we are able to
record splitting of the first sound in most normal
individuals. We have also noted that one must
frequently employ significant low frequency filtration in order to appreciate splitting on graphic
recordings. Thus one's recording equipment and
adjustments may have much to do with whether
splitting of sounds is demonstrated graphically,
even though it may be easily heard. Phonocardiographers are often faced with the difficult problem
EDITORIALS
6
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of telling the auscultator what he is hearing, when
he can record both a fourth heart sound and
splitting of the first sound. All these sound
phenomena may be recorded in most patients
regardless of presence or absence of disease; yet,
the clinician usually hears only two sound components instead of three. Based upon characteristics of
human audition however, it is quite likely that in
most cases, one hears first heart sound splitting or
an ejection click far more commonly than he hears a
fourth heart sound. Unfortunately, this impression
is extremely difficult to prove with our current
techniques. The simple fact that studieg have shown
that fourth heart sounds are often erroneously
thought to be present' suggests that we are
frequently mistaking this sound for splitting of the
first heart sound. Certain adjunctive auscultatory
features may provide additional aid to the clinician
in making the distinction between fourth heart
sounds and first sound abnormalities: splitting of
the first sound or the ejection sound imparts the
sensation of two high-pitched "clicking" sounds, is
widely radiated over the preQordium, is well heard
in the upright position, and is not suppressed by
heavy pressure on the stethoscope bell or with the
use of the diaphragm chest piece. On the other
hand, the fourth sound possesses a dull "thudding"
quality, is usually localized at the apex, best heard
in the recumbent (especially left lateral decubitus)
position, and often suppressed by pressure on the
bell or with the use of the diaphragm chest piece.
Although these criteria are useful in differentiation,
I regard them as being secondary.in importance in
comparison to determination of presence or absence
of the presystolic apical thrust.
In the light of the above comments, we can take
back to the bedside certain points of practical
value: 1) Despite the fact that small fourth sounds
accompanied by small apical A waves may be
recorded graphically in most normal individuals, it
is extremely difficult to recognize fourth heart
sounds by ear alone. By and large, one probably
hears only pathologically loud fourth sounds. 2) If
one hears two discrete sounds at the time of the first
heart sound, he must be extremely circumspect in
claiming the presence of a fourth heart sound. If he
fails to palpate a discrete presystolic apical outward
movement, he is usually not justified in claiming the
presence of a fourth heart sound. 3) Regardless of
what one hears, if he feels a presystolic apical
outward movement, he is justified in assuming that
a fourth heart sound is present, with all the
hemodynamic implications this entails.
I realize that with these criteria occasionally
fourth sounds will actually be present but not
diagnosed as such, since apical presystolic motions
may on occasion be quite difficult to feel. A simple
apexcardiogram may be used, however, to resolve
difficult cases. This approach will serve to reduce or
eliminate the temptation to overdiagnose the fourth
heart sound and to restore its rightful place as a
useful tool in clinical medicine. I believe it
continues to provide an important marker of an
abnormal hemodynamic state.
MORTON E. TAVEL
References
1. RECTRA EH, KHAN AH, PIGorr VM, SPODICK DH:
Audibility of the fourth heart sound. JAMA 221: 36,
1972
2. POTAIN C: Du rhythmne cardiaque appele bruit de
galop: Bull Mem Soc Med Hop Paris. Ser 2, 12:
137, 1875
3. MOUNSEY JPD: Inspection and palpation of the cardiac
impulse. Progr Cardiovasc Dis 10: 187, 1967
4. EPSTEIN EJ, COULSHED N, BROWN AK, DOUKAS NG:
The A wave of the apexcardiogram in aortic valve
disease and cardiomyopathy. Br Heart J 30: 591,
1968
5. FOWLER NO, ADOLPH RJ: Fourth sound gallop or split
first sound? Am J Cardiol 30: 441, 1972
6. BENCHIMOL A, DIMOND EG: The normal and
abnormal apexcardiogram. Am J Cardiol 12: 368,
1963
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ME,
CAMPBELL
RW,
FEIGENBAUM
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STEINMETZ EF: The apexcardiogram and its relationship to hemodynamic events within the left heart. Br
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8. Rios JC, MASSUMI RA: Correlation between the
apexcardiogram and left ventricular pressure. Am J
Cardiol 15: 647, 1965
9. EDMONDS RE: An assessment of the utility of the
resting apexcardiogram in the epidemiology of
cardiovascular disease. Am J Cardiol 17: 180,
1966
10. ARONOW WS, CASSIDY J, UYEYAMA RR: Resting and
post exercise apexcardiogram correlated with maximal treadmill stress tests in normal subjects.
Circulation 44: 397, 1971
11. BENCHMOL A, DIMOND EG: The apexcardiogram in
normal older subjects and in patients with arteriosclerotic heart disease. Effect of exercise on the "A"
wave. Am Heart j 65: 789, 1963
12. SPODIcK DH: Fourth sound gallop or split first sound?
Am J Cardiol 31: 530, 1973
Circulation, Volume XLIX, January 1974
The Fourth Heart Sound-A Premature Requiem?
MORTON E. TAVEL
Circulation. 1974;49:4-6
doi: 10.1161/01.CIR.49.1.4
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