In people over the age of 40, the galloping heart sound can be an indication of heart complications. In this case, the sound results from leaky heart valves. As the closing of the valves produce S1 and S2, S3 follows shortly after as blood regurgitates backward in the wrong direction. This in itself may not be that harmful, but can be an indication of a more severe underlying complication.
Before you get all spiteful toward a heart that can gallop, fear not! S3 may also be the result of the elastic recoil of the heart muscle after it contracts with each beat. In younger people, especially athletes or pregnant women, this is a common and natural phenomenon , that tends to disappear by middle age not that you would notice!
Thanks for writing this — your style is engaging and clear!
Hi Jessica, interesting read. Hi yixiaos1 sorry, not sure what your first name is! Thanks for your questions!
The function of the third sound, and what it is actually produced by, depends on the context of the person. There is no concrete physiological explanation, as there is for S1 and S2. It is generally agreed on that in young age it is an indication of a healthy, high-functioning heart such as in fit athletes , while in older people it may be an indication of heart failure and a weakening of the valves. Essentially, it is approached on a case by case basis, depending on age, general health status, and what other symptoms the patient may be presenting with.
An interesting aspect of physiology that is certainly not black and white. I hope this helps!
A great article, Jessica! I had no idea we could have an extra dub! I liked your tone throughout and you structured your writing well. Sorry if I said anything wrong.. But I am not sure what you mean for these subtitles across the blog and somehow they made me feel more confused about the points you made with in the later paragraphs. Also, for content, what does the third dub actually do? I only get that the third dub exist during the young age, and might disappear later??
When the ventricles begin to contract, so do the papillary muscles in each ventricle. The papillary muscles are attached to the cusps or leaflets of the tricuspid and mitral valves via chordae tendineae heart strings. When the papillary muscles contract, the chordae tendineae become tense and thereby prevent the backflow of blood into the lower pressure environment of the atria.
The chordae tendineae act a bit like the strings on a parachute, and allow the leaflets of the valve to balloon up into the atria slightly, but not so much as to evert the cusp edges and allow back flow of blood. It is the pressure created from ventricular contraction that closes the valve, not the papillary muscles themselves. The contraction of the ventricle begins just prior to AV valves closing and prior to the semilunar valves opening. The sudden tensing of the chordae tendineae and the squeezing of the ventricles against closed semilunar valves, sends blood rushing back toward the atria, and the parachute-like valves catch the rush of blood in their leaflets causing the valve to snap shut.
The S1 sound results from reverberation within the blood associated with the sudden block of flow reversal by the valves. The delay of T1 even more than normally causes the split S1 which is heard in a right bundle branch blockage. The second heart sound, or S 2 , forms the "dub" of "lub-dub" and is composed of components A 2 aortic valve closure and P 2 pulmonary valve closure. Normally A 2 precedes P 2 especially during inspiration where a split of S 2 can be heard. It is caused by the closure of the semilunar valves the aortic valve and pulmonary valve at the end of ventricular systole and the beginning of ventricular diastole.
As the left ventricle empties, its pressure falls below the pressure in the aorta. Aortic blood flow quickly reverses back toward the left ventricle, catching the pocket-like cusps of the aortic valve, and is stopped by aortic valve closure. Similarly, as the pressure in the right ventricle falls below the pressure in the pulmonary artery , the pulmonary valve closes.
The S 2 sound results from reverberation within the blood associated with the sudden block of flow reversal.
Splitting of S2 , also known as physiological split, normally occurs during inhalation because the decrease in intrathoracic pressure increases the time needed for pulmonary pressure to exceed that of the right ventricular pressure. A widely split S2 can be associated with several different cardiovascular conditions, including left bundle branch block , pulmonary stenosis , and atrial septal defect. The rarer extra heart sounds form gallop rhythms and are heard in both normal and abnormal situations. It occurs at the beginning of diastole after S2 and is lower in pitch than S1 or S2 as it is not of valvular origin.
The third heart sound is benign in youth, some trained athletes, and sometimes in pregnancy but if it re-emerges later in life it may signal cardiac problems, such as a failing left ventricle as in dilated congestive heart failure CHF. S3 is thought to be caused by the oscillation of blood back and forth between the walls of the ventricles initiated by blood rushing in from the atria. The reason the third heart sound does not occur until the middle third of diastole is probably that during the early part of diastole, the ventricles are not filled sufficiently to create enough tension for reverberation.
It may also be a result of tensing of the chordae tendineae during rapid filling and expansion of the ventricle.
In other words, an S3 heart sound indicates increased volume of blood within the ventricle. An S3 heart sound is best heard with the bell-side of the stethoscope used for lower frequency sounds. A left-sided S3 is best heard in the left lateral decubitus position and at the apex of the heart, which is normally located in the 5th left intercostal space at the midclavicular line.
A right-sided S3 is best heard at the lower-left sternal border. The way to distinguish between a left and right-sided S3 is to observe whether it increases in intensity with inhalation or exhalation. A right-sided S3 will increase on inhalation, while a left-sided S3 will increase on exhalation.
S3 can be a normal finding in young patients but is generally pathologic over the age of The most common cause of pathologic S3 is congestive heart failure. S4 when audible in an adult is called a presystolic gallop or atrial gallop. This gallop is produced by the sound of blood being forced into a stiff or hypertrophic ventricle.
It is a sign of a pathologic state, usually a failing or hypertrophic left ventricle, as in systemic hypertension, severe valvular aortic stenosis , and hypertrophic cardiomyopathy.
The sound occurs just after atrial contraction at the end of diastole and immediately before S1, producing a rhythm sometimes referred to as the "Tennessee" gallop where S4 represents the "Ten-" syllable. The combined presence of S3 and S4 is a quadruple gallop, also known as the "Hello-Goodbye" gallop. At rapid heart rates, S3 and S4 may merge to produce a summation gallop, sometimes referred to as S7.
Atrial contraction must be present for production of an S4. It is absent in atrial fibrillation and in other rhythms in which atrial contraction does not precede ventricular contraction. Heart murmurs are produced as a result of turbulent flow of blood strong enough to produce audible noise. They are usually heard as a whooshing sound. The term murmur only refers to a sound believed to originate within blood flow through or near the heart; rapid blood velocity is necessary to produce a murmur.
Most heart problems do not produce any murmur and most valve problems also do not produce an audible murmur. Though several different cardiac conditions can cause heart murmurs, the murmurs can change markedly with the severity of the cardiac disease. An astute physician can sometimes diagnose cardiac conditions with some accuracy based largely on the murmur, related physical examination , and experience with the relative frequency of different heart conditions.
However, with the advent of better quality and wider availability of echocardiography and other techniques, heart status can be recognized and quantified much more accurately than formerly possible with only a stethoscope, examination, and experience.
Another advantage to the use of the echocardiogram is that the devices can be hand held. Inhalation decreases intrathoracic pressure which allows more venous blood to return to the right heart pulling blood into the right side of the heart via a vacuum-like effect. Therefore, right-sided heart murmurs generally increase in intensity with inhalation. The decreased more negative intrathoracic pressure has an opposite effect on the left side of the heart, making it harder for the blood to exit into circulation. Therefore, left-sided murmurs generally decrease in intensity during inhalation.
Increasing venous blood return to the right side of the heart by raising a patient's legs to a degree while lying supine produces similar effect which occurs during inhalation.
Inhalation can also produce a non-pathological split S2 which will be heard upon auscultation. With exhalation , the opposite haemodynamic changes occur: There are a number of interventions that can be performed that alter the intensity and characteristics of abnormal heart sounds. These interventions can differentiate the different heart sounds to more effectively obtain a diagnosis of the cardiac anomaly that causes the heart sound.
Clicks — Heart clicks are short, high-pitched sounds that can be appreciated with modern non-invasive imaging techniques. Rubs — The pericardial friction rub can be heard in pericarditis , an inflammation of the pericardium , the sac surrounding the heart. This is a characteristic scratching, creaking, high-pitched sound emanating from the rubbing of both layers of inflamed pericardium.
It is the loudest in systole, but can often be heard at the beginning and at the end of diastole.
Therefore, the pattern that one hears is one of: "lub-dub" pause, "lub-dub" pause, and so on. Sometimes, especially in young normal individuals, a third heart. Heart sounds are the noises generated by the beating heart and the resultant flow of blood The first heart sound, or S1, forms the "lub" of "lub-dub" and is composed of components M1 (mitral valve closure) and T1 (tricuspid valve closure).