A leaky heart valve, known medically as valve regurgitation, happens when one or more of your heart’s four valves doesn’t close tightly enough, allowing blood to flow backward. The causes range from inherited structural differences and age-related wear to infections, high blood pressure, and damage from a heart attack. Any of the four valves can develop a leak, but the mitral and aortic valves on the left side of the heart are affected most often, and the underlying cause depends heavily on which valve is involved.
How a Valve Starts to Leak
Your heart valves are thin flaps of tissue that open and shut with every heartbeat, keeping blood moving in one direction. For a valve to seal properly, the flaps (called leaflets) need to meet evenly, the ring of tissue they attach to needs to hold its shape, and the tiny cords anchoring them must stay intact. A problem with any one of these components can create a gap that lets blood slip backward.
Doctors divide causes into two broad categories. Primary regurgitation means something is wrong with the valve itself: the leaflets are floppy, scarred, torn, or infected. Secondary (or functional) regurgitation means the valve tissue is normal, but the heart chamber around it has stretched or weakened so much that the leaflets can no longer meet in the middle. This distinction matters because it changes how the condition is treated.
Mitral Valve Prolapse
Mitral valve prolapse is the single most common cause of a leaky mitral valve in developed countries. In this condition, one or both leaflets bulge backward into the upper chamber when the heart contracts. In many people the prolapse is mild and causes no significant leak. But if the leaflets become excessively stretchy or if the tiny cords (chordae tendineae) that tether them snap, the leak can become severe quickly. Cord rupture can turn a stable, mild leak into an emergency within hours.
Rheumatic Heart Disease
Rheumatic fever, triggered by untreated strep throat, used to be the leading cause of valve leaks worldwide. It still is in many lower-income countries. The illness sets off an immune reaction that scars and stiffens valve leaflets over time, preventing them from closing fully. The mitral valve is the most common target, though the aortic valve is frequently affected too. Rheumatic heart disease tends to peak in prevalence among adults in their mid-to-late twenties, then gradually declines with age, reflecting the timing of childhood infections and subsequent scarring.
Heart Attacks and Heart Muscle Disease
A heart attack can damage the small muscles inside the heart (papillary muscles) that help pull the mitral valve shut. If one of these muscles weakens or tears, the valve can leak immediately and severely. Even without direct muscle damage, a heart attack can leave behind scar tissue that causes the left ventricle to enlarge over weeks or months. As the chamber stretches, it pulls the valve’s anchoring points apart, creating a gap between the leaflets. This is the classic path to secondary mitral regurgitation.
Other forms of heart muscle disease (cardiomyopathy) that aren’t caused by blocked arteries produce the same effect. Any condition that weakens and dilates the left ventricle can distort an otherwise healthy valve into one that leaks.
Infections of the Heart Valve
Infective endocarditis occurs when bacteria or fungi settle on a heart valve and form clumps called vegetations, made of the infecting organisms, clotting proteins, and platelets. These growths produce enzymes that destroy surrounding tissue, eating into the leaflets and sometimes severing the cords that hold them in place. The result can be a sudden, severe leak. People with pre-existing valve abnormalities, artificial valves, or a history of intravenous drug use face the highest risk.
Connective Tissue Disorders
Conditions like Marfan syndrome weaken the connective tissue that gives valves and blood vessels their structure. In Marfan syndrome, the tissue loses its normal elasticity, making valve leaflets floppy and prone to prolapse. It also causes the aorta to widen, which can stretch the aortic valve ring and prevent the leaflets from sealing. The result is often both mitral valve prolapse and aortic valve regurgitation in the same person. Ehlers-Danlos syndrome and other inherited connective tissue conditions can produce similar effects.
High Blood Pressure and Aortic Problems
Chronic high blood pressure forces the left ventricle to work harder, and over time the chamber and the aorta can both enlarge. When the aorta widens at its root (where it meets the heart), it stretches the aortic valve open and the leaflets no longer overlap enough to seal. Aortic dissection, a tear in the wall of the aorta, can also distort the valve suddenly and cause a severe leak. A bicuspid aortic valve, a common congenital variation where the valve has two leaflets instead of three, makes the valve more vulnerable to both of these processes.
Right-Sided Valve Leaks
The tricuspid valve, on the right side of the heart, most often leaks for secondary reasons. High blood pressure in the lung arteries (pulmonary hypertension) forces the right ventricle to work harder. Over time the ventricle dilates and changes from its normal crescent shape to a more spherical one. Research from the Cleveland Clinic found that it’s this change in right ventricular shape and function, not damage to the tricuspid valve itself, that drives the leak. Patients with worse right ventricular function and a more spherical chamber developed the most significant regurgitation.
The pulmonary valve, the fourth and least commonly affected valve, can leak due to pulmonary hypertension as well, or from congenital heart defects. Pulmonary valve regurgitation is relatively rare in adults who weren’t born with a heart defect.
Age-Related Wear
Degenerative changes are the most common reason older adults develop valve leaks. Calcium deposits build up on valve leaflets over decades, thickening and stiffening them. This process, sometimes called calcific valve disease, tends to affect the aortic valve most. While calcification more commonly causes narrowing (stenosis), it can also prevent complete closure. Among people 70 and older, roughly 2 in 100 have calcific aortic valve disease and about 2 in 100 have degenerative mitral valve disease, making these among the most prevalent heart conditions in older age groups. Both conditions become more common with each decade of life.
Symptoms of a Leaky Valve
Mild leaks often produce no symptoms at all and are discovered incidentally during a routine exam or imaging study. As regurgitation worsens, common symptoms include shortness of breath during physical activity, fatigue, heart palpitations, and swelling in the legs and feet. Some people notice chest pressure or a persistent cough. A doctor may hear a heart murmur through a stethoscope, which is often the first clinical clue.
Because symptoms develop gradually, many people unconsciously reduce their activity level and don’t realize how much the leak is affecting them until it’s quite advanced.
When Repair or Replacement Is Needed
Not every leaky valve needs surgery. Trace or mild regurgitation is extremely common and often requires nothing more than periodic monitoring. Current guidelines from the American Heart Association and American College of Cardiology recommend intervention primarily for severe leaks, and the triggers depend on whether you have symptoms and how your heart is responding.
For a severe mitral valve leak, surgery is recommended if you develop symptoms like breathlessness or exercise intolerance, or if imaging shows your heart’s pumping strength is starting to decline, even without symptoms. When the valve anatomy is favorable, repair (rather than replacement) is preferred because outcomes are better and you avoid the lifelong need for blood thinners. For patients who are too high-risk for open surgery, a catheter-based procedure can clip the valve leaflets together to reduce the leak.
For a severe aortic valve leak, valve replacement is recommended once symptoms appear or once the heart begins to enlarge or weaken, whichever comes first. Tricuspid valve surgery is most commonly performed alongside left-sided valve surgery when both valves are affected, though isolated tricuspid repair is an option for people with severe symptoms that don’t respond to medication.
The overall goal is the same across all four valves: intervene before the heart sustains permanent damage from the extra workload of pumping blood that keeps flowing backward.