To begin this page, think about what valves close to create each of the two normal heart sounds, "lub" and "dup" (S1 and S2).
QUESTION: What valves close right at the beginning of systole as the pressure begins to increase the ventricles? Answer
QUESTION: What valves close right at the beginning of diastole as the pressure begins to fall in the ventricles? Answer
QUESTION: OK, now put it all together and indicate how the two normal hearts sounds relate to the times of systole and diastole. Answer
In addition to the normal two heart sounds, sometimes a third heart sound or a fourth heart sound (S3 and S4) occur.
The third heart sound occurs near the beginning of diastole during the rapid, passive phase of ventricular filling. In certain individuals, a sound occurs at this time as the ventricles spring open just after the end of their contraction.
Sometimes a third heart sound occurs normally. In this case, the individual is most likely a child or possibly an adult less than 40. Sound is produced as blood rushes rapidly into supple ventricles, suddenly stretching the chordae tendineae and other parts of the ventricles.
A third heart sound occurs pathologically when the atrial pressure is unusually high, which typically occurs when the extracellular fluid volume, and thus the blood volume, is much higher than normal. For reasons we will discuss later, such a "volume overload" is characteristic of congestive heart failure.
A fourth heart sound occurs near the end of diastole at the time atrial contraction. A sound occuring at this time is pathological and is the result of stiff ventricles. (Again, more on stiff ventricles later when we discuss topics such as aortic stenosis, hypertension and diastolic heart failure.)
[OPTIONAL: If you like, click on the following link and you can listen to third and fourth heart sounds. Near the top of the page you will see three buttons for normal, S3 and S4. Sounds: Third and Fourth ]
Sometimes, if the two ventricles are not contracting exactly in synchrony, the aortic and pulmonary valves do not close at exactly the same time, producing a split second heart sound. Instead of the normal "lub-dup" sound, a "lub-dadup" sound occurs.
This usually occurs normally to a very small extent on inspiration. But to hear it you need to listen very carefully in a quiet place. It is subtle.
A more pronounced and obvious split sound occurs when the ventricles are not contracting synchronously for a pathological reason, such as a bundle branch block.
[OPTIONAL: If you like, click on the following link and you can listen to a spit heart sound. Near the top of the page you will see a button for normal and one for a split S2. Sounds: Split S2 ]
Heart murmurs occur due to turbulent blood flow. As we will discuss in class, this occurs abnormally as blood moves too rapidly through a narrow space. This occurs with stenosis of a valve, in which the leaflets do not open fully, creating a narrowed opening. A murmur can also occur with insufficiency (regurgitation), in which blood flows backward through a valve that does not close entirely.
REQUIRED: While the actual heart sounds themselves are optional, you should know whether a murmur is systolic or diastolic for either stenosis or insufficiency for any of the four valves. In other words, does the heart sound "lub-shhh-dup" or "lub-dup-shhh" in each case.
With patients in their 70s and 80s, aortic stenosis is typically "senile", presumably from wear and tear on the valve leaflets. Damage to the endothelium and connective tissue leads to pronounced calcification, which narrows the orifice of the valve .
Since the left ventricle must generate more pressure to pump blood through the narrowed valve, the left ventricle hypertrophies to a greater wall thickness.
The high pressures in the left ventricle also tends to elevate pressures in the pulmonary circulation, leading to pulmonary edema and congestive heart failure (to be discussed later on).
At the same time, the poor flow forward through the aortic valve can lead to symptoms such as angina and syncope.
QUESTION:Will this murmur occur during systole or diastole? Answer
[OPTIONAL: If you like, click on the following link and you can listen to a murmur due to aortic stenosis. Near the top of the page you will see a button for AS late. Sounds: Aortic Stenosis]
Younger patients with aortic stenosis often congenitally have an aortic valve with only two cusps (leaflets) . Flow through these valves is abnormal, leading to damage to the endothelium and connective tissue. Over the years, the resulting fibrosis and calcification narrows the valve orifice, with the end result similar to the senile from.
Rheumatic heart disease is a complication that can develop following an acute streptococcal infection, especially if the infection leads to pharyngitis ("strep throat"). About 3% of these patients develop rheumatic fever about two to three weeks after the infection.
Various tissues are involved, but carditis has the most consequences. Bacteria do not colonize the heart. Possibly the inflammation is due to antibodies against the streptococcus bacteria cross-reacting with molecules in the heart.
Fifty years ago, rheumatic heart disease was a common cause of valve problems. But its incidence has considerably decreased in the United States and the rest of the developed world. Occasional outbreaks occur. But in the developing world, it is still a serious problem, with children and young adults mainly affected.
The mitral valve is most commonly involved, although other valves may be affected too. It may takes years for symptoms to appear. The inflammed leaflets thicken, fuse at the edges and calcify.
The resulting mitral stenosis causes pressure in the left atrium to increase. Subsequently, the volume of blood in the pulmonary circulation increases, leading to pulmonary edema. Thus, one symptom is shortness of breath, which is called dyspnea. These symptoms can then progress to actual congestive heart failure.
[OPTIONAL: If you like, click on the following link and you can listen to a murmur due to mitral stenosis. Near the top of the page you will see a button for MS. Sounds: Mitral Stenosis]
Infective endocarditis occurs when bacteria infect a valve in the heart. The cause might be nosocomial; that is, due to medical treatment in the hospital. Catheters and replacement of heart valves are two possible situations that might lead to infective endocarditis. Or, for example, an intravenous drug user may inject a skin bacterium, Staphlococcus aureus, along with the drug.
Left untreated, infective endocarditis is fatal.
At the inflammed valve leaflets, vegetations grow from accumulating platelets and fibrin. Bacteria readily colonize these growing, amorphous vegetations.
Damage to the valve leaflets might lead, for example, to aortic or mitral insufficiency (regurgitation). One symptom may be intolerance to exercise, because it is difficult to increase the cardiac output. Also, with mitral insufficiency, pulmonary pressures are elevated, possibly creating pulmonary edema.
QUESTION:Will the murmur in mitral insufficency (regurgitation) occur during systole or diastole? Answer
[OPTIONAL: If you like, click on the following link and you can listen to a murmur due to mitral insufficiency (regurgitation). Near the top of the page you will see a button for MR. Sounds: Mitral Insufficiency]