Forth sound gallop or split first sound?

Prevalence of the third and fourth heart sound in asymptomatic adults

The prevalence of abnormal diastolic heart sounds in asymptomatic adults has been the subject of great debate. The authors determined the prevalence of an electronically detected S3 and S4 in 1329 asymptomatic adults between the ages of 18 and 94. The authors also investigated the relationship between abnormal diastolic heart sounds, age, and electrocardiography. The overall prevalence of S3 was 10.0% (95% confidence interval [CI], 8.1%-12.2%), S4 was 15.6% (95% CI, 13.2%-18.2%), and both S3 and S4 were 3.5% (95% CI, 2.4%-5.0%). Using multinomial logistic regression, increasing age was found to decrease the odds of an S3 being heard (odds ratio, 0.96; 95% CI, 0.95-0.96) and increase the odds of an S4 being heard (odds ratio, 1.04; 95% CI, 1.03-1.05). We conclude that the prevalence of an S3 is increased earlier in life, that an S4 is less common than previous studies suggest, and that its detection, even in the elderly, should not be ignored.

Relationship of auscultatory fourth heart sound to the quantitated left atrial filling fraction

The fourth heart sound (S4) has been associated with vigorous atrial contraction. However, the presence of S4 has not been previously correlated with quantitated left atrial filling fraction. In this study, the presence of an auscultatory S4 was compared with the Doppler echocardiographically quantitated left atrial filling fraction in 41 consecutive patients in whom S4 was judged to be present or absent according to the consensus of cardiologists. Left atrial filling fraction in patients with S4 was 49% and was significantly greater than 33% found in patients without S4 (p less than 0.005). Using atrial filling fraction of 35% as a dividing line, S4 had a sensitivity of 84% and a specificity of 75% for determining left atrial filling fraction greater than or equal to 35%. Furthermore, of 25 patients with S4, 21 (84%) had atrial filling fraction greater than or equal to or less than 35%, and of 16 patients without S4, 12 (75%) had atrial filling fraction less than 35%. Thus, the presence or the absence of S4 is quantitatively related to the left atrial filling fraction and appears to predict atrial filling fraction greater than or equal to or less than 35% reasonably well.

Relation of intensity of cardiac sounds to age

The absolute intensity of the first (S1), third (S3), and fourth (S4) heart sounds (in mm Hg) and the relative intensity of S4 compared with S1 were measured in 146 normal persons, aged 8 to 91 years, using an infinite time-constant, calibrated pressure mechanocardiograph applied to the chest wall with a loading pressure of 400 mm Hg. The absolute intensity of S1 (r = 0.28) and S3 (r = 0.43) decreases with age, but the absolute intensity of S4 does not increase with age (r = 0.06). Therefore, the relative intensity of S4 compared with S1 increases with age (r = 0.31). This finding may explain the increased frequency of S4 in qualitative phonocardiograms in older persons.

Relation of P-S4 interval to left ventricular end-diastolic pressure

Reports have suggested that the interval between P wave onset and the fourth heart sound (P-S4 interval) reflects changes in left ventricular myocardial stiffness. We made simultaneous measurements of the P-S4 or atrial electrogram to S4 (A-S4) interval and left ventricular pressure in 19 patients with coronary artery disease who were studied before and after atrial pacing. Thirteen patients developed angina accompanied by significant rises in their end-diastolic pressure and a consistent decrease in P-S4 or A-S4 interval; whereas the six patients who had atrial pacing without the development of angina had no change in end-diastolic pressure, P-S4, or A-S4 interval. The resting data showed in inverse correlation between left ventricular end-diastolic pressure and the P-S4 interval. In addition, the P-S4 interval let us discriminate between patients with normal and abnormal end-diastolic pressure (greater than 15 mmHg).

The fourth heart sound in patients without demonstrable heart disease

One hundred patients, 17 to 67 years of age, had normal hearts diagnosed on the basis of complete right and left heart catheterization and coronary cineangiography. Phonocardiograms were obtained from each patient, providing an average of 17 recordings per subject for analysis; 75/100 (75%) subjects had a recordable fourth sound; 60/75 (80%) of the latter group had an audible fourth heart sound. It is concluded that recordable and audible fourth heart sounds are common findings in subjects without catheterization evidence of cardiovascular disease.

Auscultatory perception of the fourth heart sound: effects of interval form fourth to first sound (S4-S1) and aging

A clinically heterogeneous group of 48 subjects (aged 19 to 76 years) were searched for a fourth heart sound (S4) by three independent "blind" auscultators. Phonocardiograms recorded immediately after auscultation were measured by another "blind" observer. An S4 was identified in 32 subjects (67 per cent) in phonocardiograms with nominal filter peaks of both 70 and 35 hertz. Results in these subjects revealed two groups by auscultatory performance: those with an "easily heard" and those with an "easily missed" S4. Subjects with an "easily missed" S4 were significantly younger than those with an "easily heard" S4 (31.2 +/- 2.8 years versus 50.0 +/- 4.0 years, P less than 0.001). P-R and P-S4 intervals and relative amplitude of S4 (ratio of fourth to first heart sound [S1] amplitude) were not significantly different in the two groups. Splitting of the first heart sound (S1) was observed more frequently in the phonocardiogram of patients with an "easily missed" S4, but this trend did not reach statistical significance. The interval between S4 and the low frequency component of S1 was significantly short in those with an "easily heard" S4 (49.4 +/- 4.1 msec versus 70.0 +/- 5.0 msec, P less than 0.005). The mean S4-S1 (low frequency component) interval for the group with an "easily heard" S4 approximated 1 cycle length for S4 vibrations, a finding consistent with temporal acoustic summation. An alternate hypothesis is modification of S1.

When does a fourth sound become an atrial gallop?

A study of the fourth sound was conducted on 100 normal subjects (ages 1-88 years) and 42 clinical cases with either aortic stenosis, systemic hypertension or coronary heart disease. This study was based on the graphic recognition of a presystolic sound when the tracing was taken with the use of one or more of 5 different high pass filters. Attention was paid to the existence of the fourth sound, its magnitude, and its vibrational frequency. In general it was accepted that a magnitude of 1/2 of the first heart sound or a frequency of 30 Hz denoted a pathologic fourth sound. However, exceptions were found among normal subjects, so that only the combination of the two criteria could be considered highly significant for a pathologic phenomenon (gallop). Patients with aortic stenosis presented an increase in magnitude of the fourth sound but incidence and vibrational frequency were similar to those of controls. Patients with hypertension had a greater incidence of fourth sounds, especially in middle age (100%); middle age patients usually had a greater magnitude while older patients had more often an increase in vibrational frequency. Patients with coronary heart disease (evidence of old infarcts) had an increase in the incidence, magnitude, and vibrational frequency in comparison with controls. These data and the cause of the fourth sound are discussed. The fourth sound has been repeatedly studied in the past, both as an auscultatory finding and a graphic phenomenon. Attempts were made for separating the normal fourth sound from that denoting a pathological phenomenon but, so far, no clear cut criteria for the differentiation have been obtained. We thought, therefore, that a new study was indicated.

The apical A wave versus the fourth heart sound in assessing the severity of aortic stenosis

The height of the "a" wave of the apexcardiogram was evaluated as a marker for critical aortic stenosis in patients over 40. Critical aoritc stenosis was defined as an aortic valve area less than .75 cm-2 with no more than mild aortic insufficiency. Phonocardiograms and apexcardiograms were performed on 72 patients with catheterization proven aortic stenosis and on 14 normal controls, all over age 40. The height of the "a" wave of the apexcardiogram was measured as a percentage of the e to o excursion (a/e-o). Fourth heart sound gallops ( S4G) were recorded in 71% (11 of 14) of normal controls, 86% (6 of 7) of patients with less than critical aortic stenosis, and 85% ( 55 of 65) of patients with critical aortic stenosis. The a/e-o was less than 16% in all normals or patients with less than critical aortic stenosis. The a/e-o exceeded 16% in 45% (29 of 65) with critical aortic stenosis. Audibility of the S4G bore no relationship to recordability, apical "a" wave geight, or the severity of the aortic stenosis. In conclusion, therefore, we believe that when one is confronted with findings suggestive of aortic stenosis, the finding of a palpable apical "a" wave (or an "a" wave height of greater than 16% of the total complex on the apexcardiogram) is an important positive feature, suggesting severe aortic stenosis. Its absence, however, does not exclude severe valvar obstruction. Probably because of auscultatory inaccuracy in this condition, the apparent presence or absence of an S4G has not been of much aid in this evaluation. This sound, however, might be more useful in a carefully performed prospective study.