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Communications to the Editor |

Audibility of Fourth Heart Sound FREE TO VIEW

David H. Spodick, MD, FCCP
Author and Funding Information

Director, Cardiovascular Fellowship Training Program Saint Vincent Hospital Worcester, MA



Chest. 1999;115(4):1218-1219. doi:10.1378/chest.115.4.1218-a
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Published online

To the Editor:

Robert Adolph’s1predictably well written and closely reasoned editorial mischaracterizes one of my group’s publications on the fourth heart sound.2 Nowhere does that or any of our reports on S4 equate recordability with audibility. We have used the phonocardiograph to indicate the presence and the potential audibility of fourth heart sounds in various groups of patients and normal individuals and were the first to employ mutually blinded auscultators.,2 In our study cited by Adolph, we investigated an epidemiologic cohort (Framingham Heart Study) of ambulatory normal and abnormal subjects, to whose medical status the auscultators were totally blinded until after completion of data collection.2

What each phonocardiographic system records depends critically on its technical characteristics, particularly the microphones and filters. However, the notion that any audible fourth heart sound equated with abnormality arose (1) from loud (and particularly palpable) fourth heart sounds, which virtually always indicate heart disease, and (2) the filter characteristics of the prevalent Hewlett Packard-type phonocardiographs in which sharp filter roll-offs pass only low-frequency heart sounds with high energies. We used not only Hewlett Packard3 (McMinnville, OR) equipment but also Schwartzer2 (Framingham, MA) and Siemens4 (Iselin, NJ) recording systems using filters with much gentler roll-offs and therefore increased sensitivity to low-frequency vibrations. (Perhaps they were too sensitive, but short of a head-to-head comparison, we cannot know this.) The logarithmic auditory response of the human ear is such that disproportionately higher energies (amplitudes) are required for low-frequency sounds to be perceived; it is not surprising that only the loud S4s and S3s occasion no disagreement.

But where is the S4 intensity threshold for pathogenicity? At some product of amplitude and frequency, potentially acoustic events can be recorded at all times when hemodynamic transients set up vibratory transients. Yet, phonocardiography provides the only standard for potential audibility. Moreover, to “objectify” the ability to auscultate (implying audibility), only mutually blinded auscultators will do, as in the study by Lok and colleagues.5Of course, interpretation of an S4 vs an S1 component depends on both experience and auscultatory teaching. Auscultators will generally anticipate events that have been emphasized in their teaching. For my students, emphasis on S4 sounds, especially in normal elderly individuals, has led—rightly or wrongly—to their frequent detection. S4 sounds associated with normal aging6 correlate nicely with increasing Doppler A wave velocity in normal aging.

An important consideration with regard to S4 is the complex of acoustic events surrounding and including the first heart sound.7I had the privilege of working in the acoustic (not phonocardiographic) laboratory of Massachusetts Institute of Technology with acousticians of the Bolt, Beranek and Newman group (who expertized the Nixon tapes). In preliminary studies, we determined that every vibration, ie, the fourth heart sound and each of the four potentially audible vibrations of the first heart sound, could be gated at some level of amplification and made audible to all observers by the computer. We also determined that not only energy and frequency were important but, because of the phenomena of backward and forward masking and temporal summation of adjacent sound components, the time between the various vibrations was critical. When the complete S4-S1 complex was resynthesized, only two acoustic events could be heard in proximity to and including the first heart sound, even when all components were equally amplified. (This work was not extended because I thereafter left Boston.) Unfortunately, in an era when classic diagnostic skills are declining, these problems may not be investigated further.8 However, in another work by us, the critical nature of the temporal relation of the fourth heart sound to the first heart sound and its components was demonstrated again, using blinded auscultators and phonocardiography.4

The poor observer agreement in the well-designed study by Lok and colleagues5 was not unanticipated. The senior author, Dr. Ranganathan, has an international reputation for diagnostic acumen; it is possible that if all his observers were at an equal level, better agreement might have resulted.8(However, at a national meeting of experienced auscultators from all over the country, there was astonishing lack of agreement when they were exposed sequentially to 20 tapes and separately to a single subject with a known murmur.9)

My main disagreement with Lok and colleagues5 is in the term gold standard. Presumably, gold means ultimate or absolute. Unlike the alchemists, scientists do not recognize immutable standards.,10 Furthermore, linguistically, it is a slipshod extension from financial terminology where it has a precise meaning. In this respect, platinum is more valuable than gold—indeed, the metric system is standardized on a platinum rod maintained in Paris. The term gold standard was introduced by coronary arteriographers in the 1960s, before which we had “standards” just as any other profession. Gold standard, like track record, is linguistic excess baggage and is scientifically equally repugnant; it should be discouraged.

Correspondence to: David H. Spodick, Cardiology Division, Saint Vincent Hospital, 25 Winthrop Street, Worcester, MA 01604-4593

Adolph, RJ (1998) In defense of the stethoscope [editorial].Chest114,1235-1236. [CrossRef]
 
Rectra, EH, Khan, AH, Pigott, VM, et al Audibility of the fourth heart sound: a prospective, blind auscultatory and polygraphic investigation.JAMA1972;221,36-41. [CrossRef]
 
Spodick, DH, Lance, VQ Noninvasive stress testing: methodology for elimination of the phonocardiogram.Circulation1976;53,673-676. [CrossRef]
 
Swistak, M, Mushlin, H, Spodick, DH Comparative prevalence of the fourth heart sound in hypertensive and matched normal persons.Am J Cardiol1974;33,614-616. [CrossRef]
 
Lok, CE, Morgan, CD, Ranganathan, N The accuracy and interobserver agreement in detecting the gallop sounds by cardiac auscultation.Chest1998;114,1283-1288. [CrossRef]
 
Spodick, DH, Quarry-Pigott, VM The fourth heart sound as a normal finding in older persons.N Engl J Med1973;288,140-141. [CrossRef]
 
Spodick, DH Perception of binary acoustic events associated with the first heart sound [editorial].Am Heart J1977;93,137-140. [CrossRef]
 
Zoneraich, S, Spodick, DH Bedside science reduces laboratory art: appropriate use of physical findings to reduce reliance on sophisticated and expensive methods.Circulation1995;91,2089-2092. [CrossRef]
 
Spodick, DH On experts and expertise: the effect of variability in observer performance.Am J Cardiol1975;36,592-596. [CrossRef]
 
Spodick, DH Cardiolocution: the cardiologist’s assault on English.Am J Cardiol1981;48,973-974. [CrossRef]
 

Figures

Tables

References

Adolph, RJ (1998) In defense of the stethoscope [editorial].Chest114,1235-1236. [CrossRef]
 
Rectra, EH, Khan, AH, Pigott, VM, et al Audibility of the fourth heart sound: a prospective, blind auscultatory and polygraphic investigation.JAMA1972;221,36-41. [CrossRef]
 
Spodick, DH, Lance, VQ Noninvasive stress testing: methodology for elimination of the phonocardiogram.Circulation1976;53,673-676. [CrossRef]
 
Swistak, M, Mushlin, H, Spodick, DH Comparative prevalence of the fourth heart sound in hypertensive and matched normal persons.Am J Cardiol1974;33,614-616. [CrossRef]
 
Lok, CE, Morgan, CD, Ranganathan, N The accuracy and interobserver agreement in detecting the gallop sounds by cardiac auscultation.Chest1998;114,1283-1288. [CrossRef]
 
Spodick, DH, Quarry-Pigott, VM The fourth heart sound as a normal finding in older persons.N Engl J Med1973;288,140-141. [CrossRef]
 
Spodick, DH Perception of binary acoustic events associated with the first heart sound [editorial].Am Heart J1977;93,137-140. [CrossRef]
 
Zoneraich, S, Spodick, DH Bedside science reduces laboratory art: appropriate use of physical findings to reduce reliance on sophisticated and expensive methods.Circulation1995;91,2089-2092. [CrossRef]
 
Spodick, DH On experts and expertise: the effect of variability in observer performance.Am J Cardiol1975;36,592-596. [CrossRef]
 
Spodick, DH Cardiolocution: the cardiologist’s assault on English.Am J Cardiol1981;48,973-974. [CrossRef]
 
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