A heart murmur is a whooshing or swishing noise heard through a stethoscope, created by turbulent blood flow across the heart’s valves. While many murmurs are harmless, others signal a problem, such as a valve allowing blood to flow backward. Tricuspid Regurgitation (TR) is one such condition involving the tricuspid valve, and its characteristic sound is defined by the heart’s pumping rhythm.
Understanding the Heartbeat Cycle
The heart operates in a repeating sequence known as the cardiac cycle, which is divided into two main phases: systole and diastole. Systole is the contraction phase, where the ventricles squeeze to eject blood out to the rest of the body and the lungs. During this period, the semilunar valves (aortic and pulmonary) open to allow blood ejection.
Diastole, the relaxation and filling phase, is when the ventricles relax and the heart chambers fill with blood. The atrioventricular (AV) valves, including the mitral and tricuspid valves, are open during diastole to allow blood to flow from the atria into the ventricles. A healthy heart produces two distinct sounds, often called “lub-dub,” which represent the closing of the heart valves.
The “lub,” or S1 sound, marks the beginning of systole and is caused by the closing of the AV valves. The “dub,” or S2 sound, marks the end of systole and the beginning of diastole, created by the closing of the semilunar valves. Murmurs are classified based on when they occur relative to these two sounds; a systolic murmur happens between S1 and S2. The tricuspid valve must close tightly at the start of systole to prevent blood from flowing backward.
The Tricuspid Regurgitation Sound Explained
Tricuspid Regurgitation is a systolic murmur, meaning the abnormal sound is heard during the heart’s contraction phase. This timing results directly from the tricuspid valve’s failure to close completely when the right ventricle contracts. When the right ventricle contracts during systole, the pressure inside the ventricle rises sharply.
If the tricuspid valve is incompetent, this high-pressure contraction forces blood backward, or “regurgitates,” through the leaky valve and into the right atrium. This turbulent backward flow creates the characteristic murmur. The sound is typically described as a holosystolic or pansystolic murmur because it can be heard continuously throughout the entire duration of systole, from S1 to S2. A characteristic feature is that the murmur often becomes louder when a person takes a deep breath in, a phenomenon called Carvallo’s sign.
What Leads to Tricuspid Regurgitation
Tricuspid regurgitation is categorized into primary and secondary types based on its cause. Primary TR, which is less common, results from a problem with the valve leaflets or the supporting structures themselves. This can be caused by conditions such as infective endocarditis, which damages the valve tissue, or congenital defects like Ebstein’s anomaly.
Secondary, or functional, TR is significantly more prevalent, accounting for the vast majority of moderate to severe cases. In this type, the valve leaflets are structurally normal, but the valve fails to close because the right side of the heart has enlarged. When the right ventricle or the right atrium dilates, the ring of tissue supporting the valve, known as the tricuspid annulus, stretches and widens. This annular dilation pulls the valve leaflets apart, preventing them from meeting properly to form a seal during systole.
The most frequent underlying causes for this right heart enlargement include left-sided heart failure and pulmonary hypertension. Left-sided failure leads to a backup of pressure into the lung circulation, which increases the pressure the right ventricle must pump against. This sustained high pressure causes the right ventricle to remodel and dilate, resulting in secondary TR.
Evaluation and Management
Once a systolic murmur suggesting tricuspid regurgitation is detected, the next step in diagnosis is a comprehensive imaging study. The preferred non-invasive tool is the echocardiogram, which uses ultrasound waves to produce real-time images of the heart. This imaging allows physicians to visually confirm the backward flow of blood through the tricuspid valve and determine the severity of the regurgitation, which is graded as mild, moderate, or severe. The echocardiogram also assesses the size and function of the right ventricle and right atrium, helping to distinguish between primary and secondary TR.
Management of tricuspid regurgitation generally focuses on treating the underlying cause, especially in cases of secondary TR. This approach often involves medical therapy to manage associated conditions like heart failure or pulmonary hypertension. Medications such as diuretics are commonly used to relieve the fluid retention and congestion that result from the right-sided heart strain.
Surgical intervention, such as valve repair or replacement, is usually reserved for patients with severe symptoms or for those who are already undergoing surgery for other heart valve issues. Newer, less invasive transcatheter procedures are also being developed and increasingly used for patients who are considered high-risk for traditional open-heart surgery.