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Comparative prevalence of the fourth heart sound in hypertensive and matched normal persons
Comparative Prevalence of the Fourth Heart Sound in Hypertensive and Matched Normal Persons
MlCHAEL SWISTAK, BS HARRY MUSHLIN, MD DAVID H. SPODICK, MD, FACC Boston, Massachusetts
From the Cardiology Division, Medical Service, Lemuel Shattuck Hospital and the Department of Medicine, Tufts University School of Medicine, Boston, Mass. This study was supported by a grant from the John Hancock Mutual Life Insurance Company, Boston, Mass. Manuscript accepted October 24. 1973. Address for reprints: David H. Spodick, MD, Lemuel Shattuck Hospital, 170 Morton St., Boston, Mass. 02130.
614
May 1974
The Amerkan
Occurrence of the fourth heart sound (S4) as a physiologic phenomenon would limit its usefulness as a discriminator of disease. Reports of a high prevalence rate of S 4, as determined by auscultation and by phonocardiography in normal older persons, have provoked support and rebuttal. A blind, randomized phonocardiographic study of 50 normal and 50 age- and sex-matched hypertensive persons (mean age 53.9 f 6.6 years) drawn from an outpatient screening clinic showed a high and virtually equal prevalence of Ss (35 instances in each group) or possible S4 (3 and 5 cases, respectively). It appears that in middleaged persons, as in older persons, there is a high and equal prevalence rate of S4. Ouantitative studies appear to be indicated to determine when this sound can be considered a presystolic gallop.
Auscultatory or graphic evidence of a distinct “atrial,” or fourth, heart sound (SJ has been uniformly considered a sign of ventricular abnormality.1-4 Recently, this view was challenged in epidemiologic studies utilizing controlled protocols. These demonstrated in both normal and abnormal older subjects a 70 to 75 percent prevalence rate of S4, as determined by blind auscultation plus phonocardiography5s6 and also, in larger groups, by blindly interpreted phonocardiograms7,s This unexpectedly high and unexpectedly equal prevalence rate is indirectly supported by the laboratory studies of other investigatorsg and by certain clinical experience.lO Moreover, the occurrence of S4 as a normal phenomenon in older persons appears to explain the finding in aortic stenosis that the presence of an S4 correlates reliably with the severity of the lesion up to age 40 but thereafter is lost as a discriminator.” The elaborately blinded protocols of the epidemiologic S4 investigations5m8 should have eliminated bias in the results. These studies demonstrated that the auscultators were not deceived by the relative amplitude of S4 (S&r ratio), by phonocardiographically split high frequency components of the first heart sound (Sr) or by a large low frequency component of SI. 59s Any subaudible presystolic pulsations should have been eliminated or sharply attenuated by the frequency range utilized (35 to 70 Hz). Moreover, the microphone in these studies was positioned between the apex and the left sternal border to avoid the low frequency vibrations corresponding to chest wall displacement during the apical A wave.12 Nevertheless, although no other blind investigations have been reported, the common finding of S4 as a physiologic event has been both challenged4J3 and supportedlo by expert observers in carefully reasoned, authoritative analyses of experience with this phenomenon and its auscultatory and graphic documentation. Because of the controversy and the evident importance of the issue of the “atrial” sound as a sign of cardiac abnormality, we investigated the phonocardiographic prevalence of S4 in a different, somewhat younger, patient population using different technical equipment (al-
Journalof CARDIOLOGY
Volume 33
PREVALENCE OF FOURTH HEART SOUND-SWISTAK
ET AL.
FIGURE 1. Fourth heart sounds (S4) in normal subjects (upper ano ieft pSnel8). Lower rtght panel shows a vibration scored as “maybe”
S4 (?S4). In each panel, from top to bottom: electrocardiographic lead II, phonocardiogram (70 Hz) and summits of the right carotid displacement pulse.
FIGURE 2. Fourth heart sounds (S4) in hypertensive subjects (upper and left lower panels). Lower right panel shows vibration scored as “maybe” (?S4). In each panel, from top to bottom: electrocardiographic lead II. phonocardiogram (70 Hz) and summits of the right carotid displacement pulse.
though in the same filter range) and a different protocol for assigning patients but equally stringent blinding of observers. The previous investigations covered from 122 to 250 consecutively studied 50 to 80 year old normal persons and patients with a variety of cardiovascular disorders.s-s This investigation involves 41 to 65 year old normal persons matched by
sex and age with ambulatory hypertensive subjects. The ambulatory status of both groups implies better cardiovascular function than in hospitalized groups (and thus a reduced prevalence of abnormal heart sounds). Hypertensive subjects were studied because this group is expected to have a high prevalence rate of sq. 10,14,15 May 1974
The Am&can
Journal of CARDfGLGGY
Volume 33
615
PREVALENCE OF FOURTH HEART SOUND-SWISTAK
TABLE
ET AL.
I
Prevalence of Sq in 50 Middle-Aged 50 Matched Hypertensive Subjects
Subjects Normal Male Female Total Hypertensive Male Female Total
f
Normal
Mean Age (yr) Standard Deviation
Persons and
~ Present
S4 ?
Absent
6.68 6.48
...
16 19 35
2 1 3
7 5 12
53.5 zk 6.83 54.3 zt 6.50 ...
19 16 35
1 4 5
5 5 10
53.4 f 54.2 f
Material and Methods We investigated 100 subjects aged 41 to 65 years drawn from 530 consecutively recorded individuals on a predetermined basis: After exclusion of patients with evidence of myocardial or valvular disease, 50 patients with sinus rhythm whose brachial arterial pressure was 150/90 mm Hg or greater were matched by sex and by age with an equal number of normotensive subjects who had no evidence of cardiovascular abnormality by history, physical examination, 12 lead electrocardiogram or chest roentgenogram. Phonocardiograms were registered on a Siemens (ElemaScMnander) Cardirex recorder in the filter ranges 35 and 70 Hz, using an EMT 25B microphone that was positioned well away from the apex (between the apex and the left sternal border but somewhat closer to the latter). No clinical data were revealed until all phonocardiograms were studied in random order and all results tabulated. Sd was defined as distinct low frequency vibrations consistently following every P wave and preceding the QRS complex of the electrocardiogram (Fig. 1 and 2). Thus, phonocardiograms were scored “S4-yes,” “no” or “maybe” without knowledge of the patient’s status. (Because of thicker base lines the “maybe” category was included for less distinct vibrations). The diagnostic data were independently scored “yes” or “no” for hypertension without knowledge of the phonocardiographic data. The results were then matched. Results Table I summarizes the results. When the blinding code was broken, 35 (70 percent) of the 50 hyperten-
sive patients and the identical proportion of the 50 normal subjects had scores of “&-yes.” Phonocardiograms in five hypertensive and three normal subjects were judged as “&-maybe” (Fig. 1 and 2). Insignificant sex differences are apparent in the table. The mean age for all subjects was 53.9 f 6.62 years. Discussion The presence of S4 in at least 70 percent of this normal group and the matched hypertensive patients confirms previous data showing comparable and equal prevalence of Sq in a somewhat older (50 to 80 years) population of normal subjects and patients with mixed (mainly coronary) cardiovascular abnormalities.5-8 Registration of S4 by phonocardiogram does not prove its audibility. Yet the exact significance of the audible Sq in older persons has also been questioned5,6*g,10 although there is general agreement that a very loud “atrial” sound correlates well with ventricular overloading. 4~10 (The exact loudness of this sound would be a subject for quantitative studies: If the mere presence of Sb can be normal in older persons, when does it become a presystolic gallop?). In this investigation, care was taken to ensure elimination or attenuation of low frequency precordial movements associated with the presystolic left ventricular A wave by placing the microphone well away from the apex, keeping the patient supine (thus avoiding the left lateral decubitus) and utilizing a low frequency filter cutoff of 35 Hz. We did not record an (1) the criteria used to apex cardiogram l6 because identify the timing of Sq have proved sufficient5T8J0 (that is, no other event is being registered), and (2) the A wave of the apex cardiogram merely indicates a presystolic precordial movement approximately synchronous with a left ventricular Sq. The results of our study suggest that (1) Sq is as common in middle age as it is in old age, and therefore its presence is not in itself a sign of cardiovascular abnormality; and (2) phonocardiographic and further auscultatory studies of Sq may be desirable to elucidate any quantitative characteristics that distinguish the Sq gallop from the normal Sq.
References 1. Weitzman D: The mechanism and significance of auricular sound. Br Heart J 17:70-78, 1955 2. Lewis DH, DeHz GW, Wallace JD, et al: Intracardiac phonocardiography in man. Circulation 16:764-775, 1957 3. Grayrel J: Gallop rhythm of heart: I. Atrial gallop, ventricular gallop and systolic sound. Am J Med 28:578-592. 1960 4. Fowler NO, Adolph RJ: Fourth sound gallop or split first sound? Am J Cardiol30:441-444, 1972 5. Spodlck DH, Rectra E, Khan A, et al: Audibility of the fourth heart sound (abstr). Circulation 44: Suppl ll:ll-33. 1971 6. Rectra EH, Khan AH, Plgoti VM, et al: Audibility of the fourth heart sound: a prospective, blind auscultatory and polygraphic investigation. JAMA 221:36-41, 1972 7. Spedick DH, Quarry-Plgotl VM: The fourth heart sound: normal finding in older persons. N Engl J Med 288:140-141, 1973 0. Spedick DH, Quarry-Pigott VM: Prevalence of the fourth heart sound by phonocardiography in the absence of cardiac disease. Am Heart J 87:11-14, 1974
616
May 1974
The American Journal of CARDIOLOGY
Volume 33
9. Benchimol A, Desser KB: The fourth heart sound in patients with proven normal hearts (abstr). Circulation 44: suppl ll:ll-140, 1971 10. Bethell HJN, Nixon PGF: Understanding the atrial sound. Br Heart J 35229-235, 1973 11. Caulfield WH, deLeon AC Jr, Perloff JK, et al: The clinical significance of the fourth heart sound in aortic stenosis. Am J Cardiol28:179-182, 1971 12. Spodlck DH, Quarry-Pigott VM: Letter. N Engl J Med 288:688689, 1973 13. Adolph RJ, Fowler NO: Letter. N Engl J Med 288:68&3, 1973 14. Klncald-Smith P, Barlow J: The atrial sound in hypertension and ischemic heart disease. Br Heart J 2 1:479-49 1, 1959 15. Sakamoto T, Kalto G, Ueno H: Electrocardiographic and phonocardiographic studies in hypertension. Jap Heart J 1:213-225, 1960 16. Plgoll VM, Spodlck DH: The effect of high frequency filter cutoffs on the apexcardiogram. Chest 59:240-241, 1971
MlCHAEL SWISTAK, BS HARRY MUSHLIN, MD DAVID H. SPODICK, MD, FACC Boston, Massachusetts
From the Cardiology Division, Medical Service, Lemuel Shattuck Hospital and the Department of Medicine, Tufts University School of Medicine, Boston, Mass. This study was supported by a grant from the John Hancock Mutual Life Insurance Company, Boston, Mass. Manuscript accepted October 24. 1973. Address for reprints: David H. Spodick, MD, Lemuel Shattuck Hospital, 170 Morton St., Boston, Mass. 02130.
614
May 1974
The Amerkan
Occurrence of the fourth heart sound (S4) as a physiologic phenomenon would limit its usefulness as a discriminator of disease. Reports of a high prevalence rate of S 4, as determined by auscultation and by phonocardiography in normal older persons, have provoked support and rebuttal. A blind, randomized phonocardiographic study of 50 normal and 50 age- and sex-matched hypertensive persons (mean age 53.9 f 6.6 years) drawn from an outpatient screening clinic showed a high and virtually equal prevalence of Ss (35 instances in each group) or possible S4 (3 and 5 cases, respectively). It appears that in middleaged persons, as in older persons, there is a high and equal prevalence rate of S4. Ouantitative studies appear to be indicated to determine when this sound can be considered a presystolic gallop.
Auscultatory or graphic evidence of a distinct “atrial,” or fourth, heart sound (SJ has been uniformly considered a sign of ventricular abnormality.1-4 Recently, this view was challenged in epidemiologic studies utilizing controlled protocols. These demonstrated in both normal and abnormal older subjects a 70 to 75 percent prevalence rate of S4, as determined by blind auscultation plus phonocardiography5s6 and also, in larger groups, by blindly interpreted phonocardiograms7,s This unexpectedly high and unexpectedly equal prevalence rate is indirectly supported by the laboratory studies of other investigatorsg and by certain clinical experience.lO Moreover, the occurrence of S4 as a normal phenomenon in older persons appears to explain the finding in aortic stenosis that the presence of an S4 correlates reliably with the severity of the lesion up to age 40 but thereafter is lost as a discriminator.” The elaborately blinded protocols of the epidemiologic S4 investigations5m8 should have eliminated bias in the results. These studies demonstrated that the auscultators were not deceived by the relative amplitude of S4 (S&r ratio), by phonocardiographically split high frequency components of the first heart sound (Sr) or by a large low frequency component of SI. 59s Any subaudible presystolic pulsations should have been eliminated or sharply attenuated by the frequency range utilized (35 to 70 Hz). Moreover, the microphone in these studies was positioned between the apex and the left sternal border to avoid the low frequency vibrations corresponding to chest wall displacement during the apical A wave.12 Nevertheless, although no other blind investigations have been reported, the common finding of S4 as a physiologic event has been both challenged4J3 and supportedlo by expert observers in carefully reasoned, authoritative analyses of experience with this phenomenon and its auscultatory and graphic documentation. Because of the controversy and the evident importance of the issue of the “atrial” sound as a sign of cardiac abnormality, we investigated the phonocardiographic prevalence of S4 in a different, somewhat younger, patient population using different technical equipment (al-
Journalof CARDIOLOGY
Volume 33
PREVALENCE OF FOURTH HEART SOUND-SWISTAK
ET AL.
FIGURE 1. Fourth heart sounds (S4) in normal subjects (upper ano ieft pSnel8). Lower rtght panel shows a vibration scored as “maybe”
S4 (?S4). In each panel, from top to bottom: electrocardiographic lead II, phonocardiogram (70 Hz) and summits of the right carotid displacement pulse.
FIGURE 2. Fourth heart sounds (S4) in hypertensive subjects (upper and left lower panels). Lower right panel shows vibration scored as “maybe” (?S4). In each panel, from top to bottom: electrocardiographic lead II. phonocardiogram (70 Hz) and summits of the right carotid displacement pulse.
though in the same filter range) and a different protocol for assigning patients but equally stringent blinding of observers. The previous investigations covered from 122 to 250 consecutively studied 50 to 80 year old normal persons and patients with a variety of cardiovascular disorders.s-s This investigation involves 41 to 65 year old normal persons matched by
sex and age with ambulatory hypertensive subjects. The ambulatory status of both groups implies better cardiovascular function than in hospitalized groups (and thus a reduced prevalence of abnormal heart sounds). Hypertensive subjects were studied because this group is expected to have a high prevalence rate of sq. 10,14,15 May 1974
The Am&can
Journal of CARDfGLGGY
Volume 33
615
PREVALENCE OF FOURTH HEART SOUND-SWISTAK
TABLE
ET AL.
I
Prevalence of Sq in 50 Middle-Aged 50 Matched Hypertensive Subjects
Subjects Normal Male Female Total Hypertensive Male Female Total
f
Normal
Mean Age (yr) Standard Deviation
Persons and
~ Present
S4 ?
Absent
6.68 6.48
...
16 19 35
2 1 3
7 5 12
53.5 zk 6.83 54.3 zt 6.50 ...
19 16 35
1 4 5
5 5 10
53.4 f 54.2 f
Material and Methods We investigated 100 subjects aged 41 to 65 years drawn from 530 consecutively recorded individuals on a predetermined basis: After exclusion of patients with evidence of myocardial or valvular disease, 50 patients with sinus rhythm whose brachial arterial pressure was 150/90 mm Hg or greater were matched by sex and by age with an equal number of normotensive subjects who had no evidence of cardiovascular abnormality by history, physical examination, 12 lead electrocardiogram or chest roentgenogram. Phonocardiograms were registered on a Siemens (ElemaScMnander) Cardirex recorder in the filter ranges 35 and 70 Hz, using an EMT 25B microphone that was positioned well away from the apex (between the apex and the left sternal border but somewhat closer to the latter). No clinical data were revealed until all phonocardiograms were studied in random order and all results tabulated. Sd was defined as distinct low frequency vibrations consistently following every P wave and preceding the QRS complex of the electrocardiogram (Fig. 1 and 2). Thus, phonocardiograms were scored “S4-yes,” “no” or “maybe” without knowledge of the patient’s status. (Because of thicker base lines the “maybe” category was included for less distinct vibrations). The diagnostic data were independently scored “yes” or “no” for hypertension without knowledge of the phonocardiographic data. The results were then matched. Results Table I summarizes the results. When the blinding code was broken, 35 (70 percent) of the 50 hyperten-
sive patients and the identical proportion of the 50 normal subjects had scores of “&-yes.” Phonocardiograms in five hypertensive and three normal subjects were judged as “&-maybe” (Fig. 1 and 2). Insignificant sex differences are apparent in the table. The mean age for all subjects was 53.9 f 6.62 years. Discussion The presence of S4 in at least 70 percent of this normal group and the matched hypertensive patients confirms previous data showing comparable and equal prevalence of Sq in a somewhat older (50 to 80 years) population of normal subjects and patients with mixed (mainly coronary) cardiovascular abnormalities.5-8 Registration of S4 by phonocardiogram does not prove its audibility. Yet the exact significance of the audible Sq in older persons has also been questioned5,6*g,10 although there is general agreement that a very loud “atrial” sound correlates well with ventricular overloading. 4~10 (The exact loudness of this sound would be a subject for quantitative studies: If the mere presence of Sb can be normal in older persons, when does it become a presystolic gallop?). In this investigation, care was taken to ensure elimination or attenuation of low frequency precordial movements associated with the presystolic left ventricular A wave by placing the microphone well away from the apex, keeping the patient supine (thus avoiding the left lateral decubitus) and utilizing a low frequency filter cutoff of 35 Hz. We did not record an (1) the criteria used to apex cardiogram l6 because identify the timing of Sq have proved sufficient5T8J0 (that is, no other event is being registered), and (2) the A wave of the apex cardiogram merely indicates a presystolic precordial movement approximately synchronous with a left ventricular Sq. The results of our study suggest that (1) Sq is as common in middle age as it is in old age, and therefore its presence is not in itself a sign of cardiovascular abnormality; and (2) phonocardiographic and further auscultatory studies of Sq may be desirable to elucidate any quantitative characteristics that distinguish the Sq gallop from the normal Sq.
References 1. Weitzman D: The mechanism and significance of auricular sound. Br Heart J 17:70-78, 1955 2. Lewis DH, DeHz GW, Wallace JD, et al: Intracardiac phonocardiography in man. Circulation 16:764-775, 1957 3. Grayrel J: Gallop rhythm of heart: I. Atrial gallop, ventricular gallop and systolic sound. Am J Med 28:578-592. 1960 4. Fowler NO, Adolph RJ: Fourth sound gallop or split first sound? Am J Cardiol30:441-444, 1972 5. Spodlck DH, Rectra E, Khan A, et al: Audibility of the fourth heart sound (abstr). Circulation 44: Suppl ll:ll-33. 1971 6. Rectra EH, Khan AH, Plgoti VM, et al: Audibility of the fourth heart sound: a prospective, blind auscultatory and polygraphic investigation. JAMA 221:36-41, 1972 7. Spedick DH, Quarry-Plgotl VM: The fourth heart sound: normal finding in older persons. N Engl J Med 288:140-141, 1973 0. Spedick DH, Quarry-Pigott VM: Prevalence of the fourth heart sound by phonocardiography in the absence of cardiac disease. Am Heart J 87:11-14, 1974
616
May 1974
The American Journal of CARDIOLOGY
Volume 33
9. Benchimol A, Desser KB: The fourth heart sound in patients with proven normal hearts (abstr). Circulation 44: suppl ll:ll-140, 1971 10. Bethell HJN, Nixon PGF: Understanding the atrial sound. Br Heart J 35229-235, 1973 11. Caulfield WH, deLeon AC Jr, Perloff JK, et al: The clinical significance of the fourth heart sound in aortic stenosis. Am J Cardiol28:179-182, 1971 12. Spodlck DH, Quarry-Pigott VM: Letter. N Engl J Med 288:688689, 1973 13. Adolph RJ, Fowler NO: Letter. N Engl J Med 288:68&3, 1973 14. Klncald-Smith P, Barlow J: The atrial sound in hypertension and ischemic heart disease. Br Heart J 2 1:479-49 1, 1959 15. Sakamoto T, Kalto G, Ueno H: Electrocardiographic and phonocardiographic studies in hypertension. Jap Heart J 1:213-225, 1960 16. Plgoll VM, Spodlck DH: The effect of high frequency filter cutoffs on the apexcardiogram. Chest 59:240-241, 1971