Heart sounds and disorders

Heart sounds and disorders

Examination of a healthy heart can be done by analysing the heart sound whether the primary heart sound generated by a persons heart is ok. Also examination of other heart sounds like S3 , S4 and Heart murmur condition are also practiced during analysis of heart sound and disorders.

The heart is a muscular organ in humans and other animals, which pumps blood through the blood vessels of the circulatory system. Blood provides the body with oxygen and nutrients, and also assists in the removal of metabolic wastes. The heart is located in the middle compartment of the mediastinum in the chest

Heart sounds are the noises generated by the beating heart and the resultant flow of blood through it. Specifically, the sounds reflect the turbulence created when the heart valves snap shut.

First & Second Heart Sound (Primary Heart Sound)

In healthy adults, there are two normal heart sounds often described as a lub and a dub (or dup), that occur in sequence with each heartbeat. These are the first heart sound (S1) and second heart sound (S2), produced by the closing of the AV valves and semilunar valves, respectively. In addition to these normal sounds, a variety of other sounds may be present including heart murmurs, adventitious sounds, and gallop rhythms S3 and S4.

Third & Fourth Heart sound

In addition to the normal two heart sounds, sometimes a third heart sound or a fourth heart sound (S3 –lub-dub-ta and S4- ta-lub-dub) 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 occurring at this time is pathological and is the result of stiff ventricles.

Heart Murmurs

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.

Senile Aortic Stenosis

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.

Bicuspid Aortic Valve

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

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 inflamed 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.

Infective Endocarditis

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, vegetation grow from accumulating platelets and fibrin. Bacteria readily colonize these growing, amorphous vegetation’s.

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.

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