While RHD remains asymptomatic for years in many cases, depending upon the severity of the valvular changes, it may eventually present with tiredness, feeling short of breath after exertion, and chest pain.
All these symptoms occur because the heart must work too hard to keep adequate blood flowing to the different parts of the body, like a mechanical pump with one or more valves that are leaking or too tight. Sooner or later a breakdown may occur, and the patient goes into heart failure.
Image Credit: uzhursky / Shutterstock.com
Rheumatic heart disease (RHD) is a long-term outcome of a condition called acute rheumatic fever (ARF). which typically occurs in childhood. As a result of ARF, the affected person develops inflammation of the heart valves with resulting damage and malfunction. ARF typically precedes the RHD by decades.
Normal and abnormal heart sounds
When a stethoscope is used to listen to the heart, different sounds are normally heard as the heart contracts and relaxes. These heart sounds are due to the closure of various valves in a smooth rhythm as different parts of the heart contract and relax to receive and eject blood. There are two primary heart sounds called S1 and S2.
S1 can be heard during the closure of the two valves separating the two atria from the two ventricles at the beginning of ventricular contraction. S2 arises due to the closure of the semilunar valves in the great vessels, the aorta, and pulmonary trunk, leading out of the two ventricles, at the end of systole or contraction. Additional sounds called S3 and S4 are occasionally heard in normal situations, but may also signal disease states.
Heart murmurs are abnormal sounds due to turbulent blood flow through damaged and scarred vessels or valves. Different conditions produce murmurs of different kinds and timing.
RHD valve disease
The left-sided valves are most commonly affected by RHD, with the mitral valve almost always being damaged, whereas the aortic valve is involved in 20-30% of cases and the tricuspid valve sustains damage in 15-40% of patients. However, RHD is classically a mixed valve disease, and the same valve shows different pathologic changes.
Mitral regurgitation
Mitral regurgitation is the most frequent lesion seen in RHD. The mitral valve separates the left-sided heart chambers, namely, the left atrium and the left ventricle. RHD usually causes mitral regurgitation, which is the abnormal backflow of blood through the valve during a ventricular contraction that occurs because it cannot close properly. The valve is thickened, and its movement is restricted.
In other situations, the mitral valve becomes hypermobile. At first, this condition is silent, but as it progresses, the left atrium and ventricle dilate. Left ventricular contraction is felt to become more forceful. A murmur extending throughout the period between S1 and S2 is heard. Finally, patients may present with signs of heart failure as the left side of the heart stops functioning properly.
Mitral stenosis
Most cases of mitral stenosis are due to RHD, which refers to the abnormal tightening of the mitral valve. Mitral stenosis is characterized by thick immobile leaflets with shortened attachments that cannot move enough to open the atrioventricular opening.
As a result, less blood flows through the valves during diastole, which the heart’s relaxation period, thus reducing the amount of blood available for pumping with each heartbeat. Tiredness sets in easily, and the person becomes breathless with just a little work.
Eventually, the increased amount of blood left in the left atria makes its pressure rise, which, in turn, increases the pressure within the pulmonary veins which discharge their blood into it. Finally, the blood vessels within the lungs become stiff because they are always stretched tight with blood, which causes the lungs to fill with fluid.
Symptoms such as cough, breathlessness, wheezing, and waking up at night with acute shortness of breath, all begin to appear. There may be blood in the sputum and the right side of the heart may also fail because it is harder to pump blood to the lungs. These are symptoms of very late disease and thus require intensive management.
Complications of mitral stenosis include the formation of a clot in the left atrium, because of the slow movement of blood out of this chamber. This can break off and travel in the circulation to block blood vessels elsewhere, producing stroke, pulmonary embolism, and other serious events. Another problem is atrial fibrillation or the lack of a regular atrial beat, as a result of atrial dilation, which interferes with the proper function of the heart pacemaker in the left atrial wall.
Aortic regurgitation
The aortic valve is usually affected in RHD along with the mitral valve. More specifically, the aortic valve becomes less mobile because it is thickened and nodular.
The leaflets of the aortic valve thus fail to meet in the middle, allowing blood to flow back from the aorta into the ventricle once the contraction is losing its force. As a result, less blood is available to the general circulation, which causes the left ventricle to dilate to accommodate the extra blood. Eventually, the heart fails to cope, and symptoms such as increased fatigue and breathlessness with exertion develop.
Aortic stenosis
Aortic stenosis is much less common in RHD and is almost always found in association with mitral valve disease.
Aortic stenosis develops slowly; therefore, most patients are unaware of it till much later. As this condition progresses, the aorta does not allow enough blood to flow into it, leading to excessive strain on the left ventricle and left heart failure, lack of blood supply to the head, and the coronary arteries. This results in symptoms such as fainting, chest pain on exertion, and breathlessness with work.
References
Further Reading