Diseases Of The Heart Valves
DISEASES OF THE HEART VALVES
Mitral Prolapse
Although widely recognized only within the last ten years, the syndrome of mitral prolapse is now felt to be one of the commonest of the heart valve abnormalities, affecting over ten percent of females and a lesser but not negligible number of males as well. In perhaps half of these patients, there are absolutely no symptoms.
The basic abnormality consists of a congenital or acquired enlargement and alteration in the shape of one of the three leaflets comprising the mitral valve of the heart. This valve separates the left atrium (upper chamber) from the left ventricle (lower chamber). As the ventricle contracts to send the blood into the aorta, the leaflets normally shut, thereby preventing backflow into the atrium;
it is this shutting that is largely responsible for the first of the two heart sounds. If one of the leaflets does not quite “fit,” the closing is somewhat imperfect. Some blood from the ventricle can then leak back into the atrium with each contraction. In addition, the ill-fitting leaflet may flop back into the atrium like a parachute in a breeze, and create a characteristic clicking sound through the stethoscope.
As a rule these events are of little significance, and cause no symptoms. In some cases, however, the disturbance in the normal pattern cause palpitations (heightened awareness of heartbeats by the patient), extra or irregular beats, and occasionally various unusual chest pains, dizziness, and even fainting. In the very rarest of cases, the rhythm disturbance can be severe and even result in sudden death; it is worth emphasizing that the later is extremely unusual and most cases are mild and easily treated.
One other important aspect of the syndrome is that the blood currents are altered within the heart. This can result in conditions where germs that normally enter the blood stream and are rapidly cleared by the body’s defenses can find small areas to lodge within the heart- -areas where the abnormal currents create “eddies” of blood which do not clear the bacteria away in a normal fashion. Such conditions can result in serious heart infections after bacterial contamination of the blood. Such contamination occurs regularly in all people after such things as dental cleanings, gynecologic or urologic surgery, childbirth, and other procedures. It is thus recommended that people with mitral prolapse take a few doses of antibiotics prior to and immediately after such maneuvers; this is felt to reduce the likelihood of heart infection.
Diagnosis
An astute physician can make the diagnosis simply by listening to the heart in many cases–the classical “click- murmur” sounds are unique. In other cases, the findings are either very subtle intermittent, or atypical. Sometimes listening while the patient arises from a crouching position, or squeezes the hands tightly enhances or brings out the sounds. Many patients have a typical appearance–thin chest wall, long arms, or sunken breastbone, all of which may heighten suspicion of the diagnosis. When there is doubt, an echocardiogram (see “Tests and Procedures” section of HealthNet) can often make the diagnosis.
The cause of mitral prolapse is unknown. Some cases are related to other syndromes such as Marfan’s Disease, but most probably represent some inherited abnormality of tissue structure, or some hypersensitivity of heart tissue to nervous system chemicals. There is a frequent familial tendency, but isolated cases are common.
Treatment and Prognosis
Treatment is often not necessary, once counseling and reassurance are offered. The symptoms are usually more worrisome than truly serious, and most patients accept this easily. The important exception is to take antibiotics prophylactically, as discussed above.
If any of the symptoms is so severe as to be disabling, or in the rare case where the physician detects a worrisome rhythm disturbance, medications of the “beta blocker” category are very effective and well- tolerated. Examples include metoprolol, nadolol, atenolol, and others.
It appears that survival and quality of life are rarely impaired by this disease. Although case reports of sudden death at a higher than usual frequency have been noted, most authorities consider this to be rare. The vast majority of patients can expect little or no change in their lifestyle or longevity, except for the inconvenience of antibiotics as described above.
Rheumatic Heart Disease
Rheumatic heart disease is generally understood to mean those diseases effecting the heart valves which arise after a known or suspected case of rheumatic fever, or those of unknown cause but which are very typical of rheumatic type disease, and those presumably of that cause.
Rheumatic fever will not be discussed here in detail, but generally is a syndrome of fever, joint inflammation, and neurologic complications. Its commonest cause is a preceding infection with certain strains of strep bacteria, such as in strep throat. Although the acute syndrome may subside in weeks, it seems to initiate a series of immune reactions in the body which attack the heart valves along with the germs–a sort of “innocent bystander” phenomenon. The result is rheumatic valvular disease. Treatment of strep infections in the early stage can prevent the vast majority of such cases, and it is for this reason that culturing of sore throats is so important. Fortunately the incidence of rheumatic fever seems to be declining for unknown reasons.
Types of Valve Disease
MITRAL STENOSIS
This is the most common single valve disorder to follow rheumatic fever, and about 65% of cases occur in females. The valves become thickened and stiff, and ultimately calcium deposits form on the valve leaflets. Since the function of the mitral valve is to direct and control blood flow from the left atrium to the left ventricle, eventually, this flow becomes markedly restricted.
Ten or more years may elapse between the original case of rheumatic fever and the development of symptoms from mitral stenosis, although a physician may suspect the disease much earlier from its characteristic, if sometimes subtle, murmur. Thus, young adults are the typical patients.
Symptoms
Over a period of 4 to 8 years, the patient notes shortness of breath as the heart is unable to drain the lungs adequately through the narrowed mitral opening. First noted only after exercise, this later becomes evident even at rest. As pressure builds in the lungs, blood vessels burst, and coughing of blood may occur. Finally all the symptoms of congestive heart failure (see discussion elsewhere in HealthNet) may ensue.
During the process, the left atrium enlarges markedly, visible on x-ray, and noted on exam. Rhythm disturbances, notably atrial fibrillation, occur. Finally, shock may ensue, leading to death if untreated.
Diagnosis
A combination of history, typical or worrisome murmur, signs of heart enlargement and irregular rhythm are usually the first clues, and echocardiography confirms the diagnosis. Cardiac catheterization is often done prior to treatment to better quantify the situation.
Treatment
In the early stages, avoidance of heavy exertion, and the use of salt restriction are important; the latter avoids fluid accumulations which may further strain the struggling heart. Diuretics such as hydrochlorothiazide, furosemide, and others are added as needed. Heart rhythm stabilizing drugs are useful in some cases, including quinidine, propranolol, and others. In some cases, blood clots form on the rough and thickened valve, and break off, lodging in the arteries of the body; anticoagulants such as warfarin are useful in these cases.
Surgical treatment of the diseased valve is indicated when the symptoms become dangerous or severely impair the daily life of the patient. This may involve simple stretching of the narrowed orifice, or total replacement of the valve with an artificial device. In major centers, such surgery has a mortality of under 2%. Current thinking suggests that the survival long-term is better if replacement is done before the occurrence of severe symptoms. This is a highly specialized area where the surgeon, cardiologist, and patient must consider many variables. Over two thirds of patients operated upon are alive 10 years later, and the mean age is in the 50’s at the time of surgery. Thus there is a reasonably good expectation for such patients who previously had almost no chance for survival.
MITRAL REGURGITATION
As opposed to mitral stenosis, regurgitation is more common in males, and is often noted more rapidly after the rheumatic fever episode. In this disorder, the valve opening is unable to be closed fully by the leaflets of the valve, and when the ventricle (lower chamber) contracts, the blood flows right back into the atrium from where it came, instead of into the aorta, where it belongs. This is a partial phenomenon, and symptoms are related to its severity. The ventricle must work overtime to compensate, and often hypertrophies or enlarges to impressive proportions in the process.
Symptoms
Fatigue is often the earliest symptom, but later shortness of breath occur. Fluid accumulation, sometimes noted as ankle swelling or edema may occur. Arrhythmias such as atrial fibrillation (see elsewhere in HealthNet) are sometimes noted. Finally, heart failure, shock and death may occur. It is noteable that many cases progress very slowly and never require intensive treatment. Survivals which are normal or near normal are commonplace.
Diagnosis
First suspected by its murmur on exam, mitral regurgitation is evaluated much like mitral stenosis, as described above.
Treatment
No treatment is necessary in many cases. The careful addition of appropriate drugs such as digoxin may be useful to control rhythm irregularities. Although restraint is indicated, in some cases the extent of symptoms warrants surgical valve replacement as discussed above. This is best done when symptoms are severe, but not so severe that the heart muscle is permanently damaged, as assessed by the cardiologist.
AORTIC STENOSIS
Only about one half of cases of aortic stenosis are related to rheumatic heart disease, the remainder being due largely to a congenital abnormality. In this syndrome, the opening through which the blood passes from the left ventricle to the aorta (and thereby to the rest of the body) becomes markedly narrowed. The ventricle squeezes increasingly harder, but eventually can no longer meet the challenge.
Symptoms
For many years the heart may compensate for the abnormality by contracting more rapidly and vigorously. After such a latent period, symptoms may progress very rapidly, at which time surgical treatment may sometimes be too late. The primary symptoms are: a) angina, due to inadequate blood flow through the coronary arteries arising from the first part of the aorta (see elsewhere in HealthNet), b) fainting, due to either blood pressure drop after exertion or position change or to rhythm irregularities, and c) heart failure, as described elsewhere, with shortness of breath, shock, and ultimate death.
Diagnosis
Exam findings are combined with the history, echocardiogram, electrocardiogram, x-ray, and finally cardiac catheterization in some cases to confirm the diagnosis, similar to mitral disease as noted above.
Treatment
Although medications such as diuretics or digoxin may be useful to control some of the symptoms, this disease is best treated with surgery. The difficulty is to determine when to operate.
Since many years may elapse before symptoms develop, immediate surgery for some cases may be unwarranted. On the other hand, waiting too long may increase the surgical risk, since the heart is less able to withstand the stress of the surgery. Given all the survival statistics, catheterization data, and development progression of symptoms, most authorities advise relatively early surgery in children and young adults, and a bit more patience in adults when possible. Five year survivals after surgery range from 60 to 95%, depending on the severity at the time of surgery. Without surgery survival is poor once symptoms develop.
AORTIC REGURGITATION
Aortic regurgitation occurs when the valve is damaged in such a way that the opening cannot be closed completely by the valve leaflets, thus allowing blood to wash back into the left ventricle from where it came instead of the aorta where it should be going. To the extent that this is occurring, symptoms may be mild or severe. Rheumatic fever causes most cases, but other diseases may be causative as well (syphilis, ankylosing spondylitis).
Symptoms
Often ten or more years elapse after the acute rheumatic fever episode, after which a period of compensation and relatively stable symptoms occurs. Then, shortness of breath, and later angina occur similar to aortic stenosis, except for a more progressive and less precipitous course. These are discussed elsewhere in HealthNet, under heart failure and angina. A period of ten or more years is common between onset of symptoms and death, even if untreated.
Treatment
The same medications used for the other forms of valve disease discussed above may also be used for patients with aortic regurgitation, including digoxin, diuretics, rhythm stabilizing drugs and nitroglycerine for angina. These can often defer the need for surgery.
Once symptoms of heart failure ensue, surgical valve replacement is considered. Without this treatment, average survival is a matter of a few years;
with surgery prolonged survival is common. As with other valvular disease, it is important not to wait too long for the operation, since irreversible damage to the heart musxle can dramatically increase the dangers of surgery.
General Comments
All damaged heart valves are susceptible to infection with germs that enter the blood stream; this occurs in all people normally, but is generally not dangerous. In cases of valve disease, it is possible for the heart to become infected in a serious or even life-threatening way. A detailed discussion may be found under “Endocarditis” in this section. For this discussion, it is important to recognize that special precautions are necessary to prevent this, in the form of prophylactic antibiotics prior to dental and other surgicial procedures, which routinely shower the blood with germs.
Endocarditis
Endocarditis refers to an infection of the inner layers of the heart itself, usually predominantly around the heart valves.
Normally, the smooth surface of the valves allows blood flow to proceed swiftly, with little chance for any germs which happen to be in the blood to lodge there. If this smooth surface is disrupted by disease or an artificial valve, the germs can occasionally lodge in the rough areas, multiply, and cause infection.
Every individual experiences the entry of germs into the blood daily, during activities such as vigorous tooth brushing, minor injuries, etc. Certain other circumstances such as dental cleanings, surgery in a non-sterile area such as the colon, urinary ract, or genital areas also regularly admit bacteria into the blood. In normal individuals, the body’s immune system quickly dispatches these germs from the system. As noted above, valvular disease presents special problems.
Other people at high risk for endocarditis include intravenous drug abusers, mitral prolapse patients in some cases, and patients with congenital heart disease. Immunosuppressed patients on chemotherapy, transplant drugs, or with immune diseases may get endocarditis with germs not usually associated with the infection. Yet, in up to a third of patients, no underlying previous heart disease is found.
Symptoms
In most cases where a preceding procedure is noted (which is the exception rather than the rule), symptoms begin after a few weeks. Fever, fatigue, weakness are common. Over time, the body starts to react to the presence of chronic infection with many antibodies, some of which can incidentally damage important organs such as the kidneys. The infection may throw off clumps of bacteria which lodge in the brain, spinal cord, skin, lungs, or elsewhere, causing remote infections.
On occasion the infection can be fulminant, with sudden onset of shaking chills, high fever, rapid destruction of the involved valve, and shock and death.
Diagnosis
The diagnosis can be elusive due to the nonspecific nature of the early symptoms. Clues include knowledge of previous heart disease, and subtle physical findings in the skin, back of the eye, and heart (particularly a new or changing heart murmur). A fever which lasts more than a week or two without any other explanation is suspicious.
Once suspected, cultures of at least two or three blood samples usually are positive for the responsible germ. Confirmatory tests may include echocardiography, further blood tests, and rarely, catheterization.
Treatment
Antibiotics are the mainstay of treatment; due to the nature of the infection, very high doses of potent agents must be given intravenously for many weeks. The exact choice is highly dependent on the characteristics of the bacteria involved, and even more so when the germ is more “esoteric,” such as fungi, tuberculosis, and others. Very sophisticated laboratory evaluation and consultation with an infectious disease consultant are commonplace.
In many cases, the patient may be discharged with an intravenous tubing apparatus inconspicuously in place in the collarbone area, avoiding prolonged hospitalization.
Prognosis is of course dependent on the previous health of the patient. Other factors are the particular germ involved, age, and promptness of treatment. Survival may range from 50% to 95%. There may be residual damage to the valve, even after cure. The severest cases may require surgery to remove the infected valve, though this is a last-ditch measure in most cases.
Prevention
If a patient is known to have one of the many heart valve conditions predisposing to the occurrence of endocarditis, they should receive antibiotics shortly before and for a brief period after procedures which could cause bacteria to enter the blood. The conditions include any of the rheumatic heart diseases, congenital valve diseases, mitral prolapse, artificial valves, and numerous others. The procedures include dental cleaning, oral or periodontal surgery, child birth, urinary or gynecologic procedures, colon procedures including barium x-rays and procto exams, and ear, nose, or throat procedures, among others.
Although the exact regimens recommended change frequently and vary for many procedures, a typical dental prophylaxis may include penicillin — 2 grams orally one hour before and 1 gram 6 hours after the procedure. Patients should obviously consult their doctor each time. Though these recommendations are still of unproven benefit and are certainly not totally successful, the potential benefits are almost unanimously felt to outweigh there small risk.