What Is Heart Valve Disease?
There are four valves in the heart that keep blood from flowing back, maintaining the one-way flow out of the heart. The closure of each valve is by flaps (“cusps” or “leaflets”) which shut only to the point of closure, preventing them from swinging back open past the closure point.
Left Side of the Heart (Oxygenated Blood)
- Mitral Valve: A two-leaf valve (“bicuspid” or “semi-lunar”) situated between the left atrium and left ventricle (“atrioventricular”), keeps blood in the left ventricle from flowing back into its respective atrium with ventricular contraction.
- Aortic Valve: A three-leaf valve (“tricuspid”) situated between the left ventricle and the aortic flow, keeps blood in the aortic arch from flowing back into the left ventricle after its contraction.
Right Side of the Heart (Deoxygenated Blood)
- Tricuspid Valve: A three-leaf (“tricuspid”) valve situated between the right atrium and right ventricle (“atrioventricular”), keeps blood in the right ventricle from flowing back into its respective atrium with ventricular contraction.
- Pulmonic Valve: A three-leaf valve (“tricuspid”) situated between the right ventricle and the pulmonary artery to the lungs, keeps blood in the pulmonary artery from flowing back into the right ventricle after its contraction.
Thus, the left atrioventricular (mitral) valve and the aortic valve keep blood flowing one-way through the left side of the heart and onward to the aorta; the right atrioventricular (tricuspid) valve and the pulmonary valve keep blood flowing one-way through the right side of the heart and onward to the pulmonary trunk (artery).
- Stenosis: when a valve is scarred or calcified such that it is stiff, hampering the mobility of its leaflets from closing properly or from allowing a smooth flow across them.
- Insufficiency: when damage or weakness to the structural integrity of the leaflets is such that it cannot close completely, allowing backflow of blood, called “regurgitation.”
Whether the flow is compromised by stenosis or reversed in part from insufficiency, the efficiency of the heart as a pump is decreased, the severity of valvular disease varying consistently with the severity of the compromise.
- Mitral Stenosis: Primarily in the young, rheumatic fever the leading cause. Obstruction to flow is from calcification, a scarring phenomenon.
- Mitral Regurgitation: Common in the elderly, it is caused by leaflet weakness, ischemia or infarction, or left ventricular enlargement.
- Aortic Stenosis: In the elderly, primarily, due to calcification or degeneration of the aortic valve. Most commonly, it is caused by the calcifications that result in obstructed blood flow with or without accompanying regurgitation.
- Aortic Regurgitation: Age-associated risk-based, it is due to dilation of the ascending aorta from hypertension, calcification-related stenosis, or–acutely–due to aortic dissection or endocarditis.
- Tricuspid Stenosis: Uncommon (due mainly to rheumatic fever) that causes obstruction to flow from the right atrium with ramifications back through the venous side of the body, leading to liver enlargement and edema.
- Tricuspid Regurgitation: Fairly common valvular dysfunction, caused by abnormality of the leaflets themselves or rupture of the chordae tendineae, which are the “heart strings” that keep the valve from swinging back open in a retrograde fashion. It is also caused by right ventricular enlargement due to aging and atrial fibrillation.
- Pulmonary Stenosis: Usually a congenital condition, it occurs when two of the leaflets are locked/fused together or too thick, leading to obstruction of blood flow into the pulmonary artery.
- Pulmonic Regurgitation: Leaky pulmonary valve disease caused by pulmonary hypertension, infection, or congenital heart disease.
It is noteworthy that infective endocarditis from Staphylococcus or Streptococcal infections, or others, puts the heart valves at risk, tricuspid most commonly, followed by the mitral and aortic valves, with involvement of multiple valves being common.
Signs and Symptoms
The clinically evident results of valvular disease all are due to the deviation from the normal functioning of the heart, either by distorting heart chambers behind obstruction or regurgitation, or diminution of blood flow onward when obstructed.
- Heart murmur
- Atrial or ventricular enlargement
- Chest pain
- Dyspnea (shortness of breath)
How Is Heart Valve Disease Diagnosed?
The heart’s efficiency as a pump depends on all of its parts functioning properly. The valves are an indispensable part of that physiology. All of the ways of evaluating the heart can play to advantage in diagnosing valvular heart disease, with echocardiography being the most informative in determining functional compromise in the atria, ventricles, or both.
All heart valve diagnostics begin with an in-depth history and a thorough physical exam when symptoms of chest pain, palpitations, dyspnea, or fainting result in a patient being evaluated for valvular heart disease.
A family history can reveal congenital proclivities toward structural heart defects. A drug history can highlight valve risk from anorectic drugs used in weight management, ergot derivatives for migraines, and illicit drugs such as MDMA (ecstasy). A childhood history of rheumatic fever can be a crucial clue to chronic valve disease (mitral, aortic, and tricuspid). Social history that includes tobacco products and alcohol is also essential. Obvious pertinent history includes a pre-established diagnosis of heart disease or valve repair/replacement.
Although edema, wheezing, or fatigue are easy to identify, the quintessential test that moves the diagnostics into the specific pursuit of valvular dysfunction is the auscultation of the heart. There are two easily heard heart sounds that are consistent with normal valvular function. There are also some subtle additional sounds that can be evoked with respiration and are normal. Valvular disease, however, makes the heart much noisier than it should be, when the turbulence of blood flow is created by the dysfunctional flow dynamics of valvular disease. These extra sounds are called heart murmurs, which are heard as whooshing, blowing sounds.
The positive findings don’t stop there, as other sounds that are pertinent include clicks from mitral valve prolapse, the 3rd heart sound seen in heart failure, or a 4th heart sound from aortic stenosis or mitral regurgitation.
The simple 2-dimensional chest X-ray which shows the cardiac silhouette in contrast against the aerated lung fields can demonstrate gross enlargement of the heart and pulmonary edema, for example, as a result of obstructed flow at the tricuspid valve.
The electrocardiogram (ECG) is a graphic recording of the wave of electrical impulses along the contraction vector over time, and it can demonstrate arrhythmias commonly seen in valvular disease.
- Cardiac echogram: Echocardiography is the procedure of choice in evaluating valvular heart disease and it defines the standard of care for it. It uses ultrasound to study the atrial and ventricular wall motion which is impacted by the flow abnormalities caused by valvular heart disease. The timing of cardiac sequenced events can categorize arrhythmias and the timing or delay of valvular function which can provoke them. Doppler velocimetry can determine any flow dysfunction. There are two types of echocardiography used:
- Transthoracic echogram (TTE): which is via a doppler transducer placed on the patient’s chest.
- Transesophageal echogram (TEE): which involves a transducer placed in the esophagus (gastrointestinal endoscopy). It eliminates a lot of the “clutter” of structures between the skin and the heart and so provides superior delineation of pathology. It is invasive, as compared to TTE and it requires sedation; due to its invasive nature, it also carries small risk of esophageal perforation or bleeding.
This can be used to assess exercise capacity and the need for valvular intervention (surgical repair or replacement).
How Is Heart Valve Disease Managed?
Short of actual replacement of the heart valves, there are other remedies that are indicated, depending on the site and extent of the valvular disease and whether or not it is life-compromising or life-threatening. Because the results are not as consistent or successful as with surgical repair (commissurotomy) or replacement with prosthetic valves, they are usually reserved for patients deemed unsuitable surgical candidates.
For the specific valve disease, the following are appropriate.
- Aortic valve replacement for severe disease and decreased left ventricular fraction, via either bio prosthesis or mechanical valve
- Percutaneous balloon valvotomy, reserved for those who are poor surgical risks
- Transcatheter aortic valve implantation, also for poor surgical candidates
- Aortic valve replacement is the treatment of choice
- Aortic valve repair in some endocarditis patients
- Mitral valve repair, if possible, is the treatment of choice.
- Surgical repair (commissurotomy) is the preferred surgical treatment of choice.
- Depending on the morphology of the mitral valve, percutaneous balloon valvuloplasty may be a better choice for a patient.
- Medical management with diuretics when mild
- For severe disease, repair is preferable to replacement
- Replacement is via bioprosthesis, which is preferable to mechanical valves
Other conditions associated with valvular disease, such as heart failure, hypertension, or arrhythmias, call for treatment themselves (medical or surgical) in the therapeutic search for the best outcome.
Other surgical treatments for comorbidities can be considered at the time of definitive valvular treatment. Treatment for coronary artery disease or atherosclerosis, while often indicated, add additional invasive approaches that can increase the risk of in-hospital mortality. Consequently, all combined surgical procedures must pass muster with a very careful risk-vs-benefit appraisal.
Prevention of Heart Valve Disease
Age-related or congenital heart valve disease may not lend themselves to prevention but, otherwise, prevention hinges on preventing the conditions which cause intrinsic defect in valvular leaflet structural integrity or flow dynamic abnormalities in their function.
Endocarditis is a common cause of valvular disease and treatment of it is preventative:
- In the very young, rheumatic fever can have long-term consequences on the mitral and aortic valves, called rheumatic heart disease. Its progression is prevented by early identification and antibiotic treatment when it is suspected.
- Intravenous drug abusers who cease this particular type of drug abuse protect themselves from the endocarditis that typically involves the heart valves, caused by seeding the bloodstream with infectious agents or the inadvertent injection of talc with drug preparation.
- Better dental hygiene can guard against the endocarditis from increased risk due to the intravascular seeding of bacteria seen in dental abscesses.
- Renal dialysis patients should have scrupulous interval evaluations of their implanted shunts or their iatrogenic fistulas that render dialysis access, and when inflammation indicates possible infection, blood cultures and appropriate antibiotic treatment based on them should be started immediately; shunt removal/replacement may be necessary.
Rheumatic arthritis, an immunological disease, can result in valve compromise. The conventional treatment of this and other medical illnesses can impact favorably upon the valvular dysfunction that sometimes arises from them:
- Systemic lupus erythematosus
- Aortic dissection
- Connective tissue disorders
This requires control of diabetes, blood pressure, lipid abnormalities, sedentary lifestyle, and even genetic studies when indicated.
Prevention of conditions that arise from valvular disease is also important. Such complications are often life-threatening and include the following:
- Cardiac arrhythmia
- Heart failure
- Pulmonary hypertension
- Atrial enlargement
- Ventricular enlargement
Prevention of complications from the treatment of valvular disease is another necessary component in the larger picture of prevention:
- Thrombosis on mechanical replacement valves is prevented (or treated) with anticoagulation therapy
- Recurrent endocarditis can be prevented by prophylactic antibiotics, continuously, in those at risk, along with periodic imaging via ultrasound or CT
- Mechanical failure of mechanical replacement valves, can be assessed using transesophageal echocardiography
In pregnancy, any patient with valvular heart disease is at increased risk of cardiac decompensation due to the pregnancy-related hemodynamic changes to heart rate, stroke volume, and cardiac output. Prior to a planned pregnancy, or immediately after diagnosis of an unplanned pregnancy, women with valvular disease should have echocardiography, exercise testing, as well as discontinuation of some of the medications they are on for their cardiac condition which may prove harmful to the gestating baby. Thrombosis due to the thrombogenic influence of estrogen in pregnancy is a serious threat to mechanical valves. In general, other risks are based on the presence of left heart obstruction, arrhythmias, pulmonary or atrioventricular regurgitation, and/or symptomatic heart failure. Referral to a maternal-fetal specialist is essential for a combined approach to such patients.