Right-sided heart failure can be either systolic or diastolic. It is not limited to one type. The right ventricle can fail because it pumps too weakly (systolic dysfunction) or because it becomes stiff and cannot fill properly (diastolic dysfunction). In many cases, both problems occur at the same time, especially when the underlying cause has been present for a while.
This distinction matters because the same systolic-versus-diastolic framework used for left-sided heart failure applies to the right side, even though right-sided heart failure gets far less attention in most patient-facing resources.
What Systolic and Diastolic Mean for the Right Ventricle
In systolic right heart failure, the right ventricle loses its ability to contract forcefully enough to push blood into the lungs. A normal right ventricular ejection fraction (the percentage of blood pumped out with each beat) averages about 52%, with 40% considered the lower limit of normal. When it drops below that threshold, the right ventricle is in systolic failure. This can happen after a heart attack that damages the right side, in advanced stages of pulmonary hypertension where the muscle wears out, or when an infection inflames the heart muscle directly.
In diastolic right heart failure, the right ventricle contracts adequately but cannot relax and fill with blood the way it should. Research published in Circulation found that more than half of heart failure patients showed abnormal right ventricular relaxation patterns, including slower filling speeds and a longer time for the ventricle to relax between beats. Conditions like constrictive pericarditis (where the sac around the heart becomes rigid) and tricuspid stenosis (a narrowed valve on the right side) can physically prevent the ventricle from filling, producing a similar picture.
Why People Associate It With One Type
The confusion often comes from how heart failure is taught. Most textbooks focus heavily on left-sided heart failure and split it neatly into “systolic” (weak pump, low ejection fraction) and “diastolic” (stiff pump, preserved ejection fraction). Right-sided heart failure gets mentioned almost as an afterthought, typically as a consequence of left-sided disease. That framing makes it seem like the right side doesn’t have its own systolic-diastolic distinction, but it does.
The other source of confusion is that when left-sided heart failure progresses, the backup of pressure into the lungs forces the right ventricle to work harder. Over time this can cause the right ventricle to enlarge, stiffen, and eventually weaken. So right-sided heart failure that starts as a response to high lung pressures (diastolic stress) can eventually become systolic failure as the muscle gives out. In practice, the two types blur together.
What Causes Right-Sided Heart Failure
The most common cause is left-sided heart failure. When the left ventricle struggles, blood backs up into the lungs, raising the pressure that the right ventricle has to pump against. This is the pathway responsible for the majority of right heart failure cases.
Beyond that, the causes sort into a few categories:
- Acute pressure overload: A large pulmonary embolism (blood clot in the lungs), severe pneumonia, or acute respiratory distress syndrome can suddenly spike lung pressures, overwhelming the right ventricle.
- Chronic pressure overload: Pulmonary arterial hypertension, certain congenital heart defects, and chronic lung disease gradually force the right ventricle to thicken and stiffen over months or years.
- Volume overload: Leaky right-sided heart valves or holes between heart chambers (like an atrial septal defect) flood the right ventricle with more blood than it can handle efficiently.
- Muscle damage: A right ventricular heart attack or inflammation of the heart muscle directly weakens the wall, causing systolic failure without necessarily involving the lungs at all.
- Impaired filling: Constrictive pericarditis and tricuspid stenosis physically restrict how much blood can enter the right ventricle, a purely diastolic problem.
Each of these mechanisms can produce systolic failure, diastolic failure, or a combination. The cause determines which type dominates.
How Right-Sided Heart Failure Feels
Because the right ventricle is responsible for collecting blood from the body and sending it to the lungs, failure on this side causes blood to back up into the veins. The hallmark symptoms reflect that congestion:
- Swelling in the ankles, feet, legs, and sometimes the abdomen
- Visible swelling of the neck veins
- Nausea, loss of appetite, and abdominal pain (from a congested, swollen liver)
- Unexplained weight gain from fluid retention
- Needing to urinate frequently, especially at night
These symptoms overlap regardless of whether the underlying dysfunction is systolic or diastolic. What changes is the severity and speed of onset. An acute cause like a massive pulmonary embolism can produce dramatic swelling and dangerously low blood pressure within hours. Chronic causes like pulmonary hypertension tend to produce gradually worsening leg swelling and fatigue over weeks to months.
How the Type of Dysfunction Shapes Treatment
Treatment depends heavily on what caused the right ventricle to fail and whether the problem is primarily one of weak pumping, poor filling, or excessive pressure from the lungs.
When the right ventricle faces too much pressure from the lungs, the priority is reducing that pressure. This can mean treating the underlying lung disease, dissolving or removing blood clots, or using medications that relax the blood vessels in the lungs. Correcting low oxygen levels, acid-base imbalances, and high carbon dioxide levels all help because each of these conditions causes lung blood vessels to constrict, making the right ventricle’s job harder.
When the right ventricle is overstretched from fluid overload, diuretics (water pills) or fluid removal techniques reduce the volume of blood the heart has to handle. Reducing that stretch actually helps the muscle contract more effectively, because an overly dilated ventricle loses mechanical efficiency. This is one of the few situations where removing fluid can improve both the congestion symptoms and the heart’s pumping ability at the same time.
When the primary problem is weak contraction (systolic failure) with normal lung pressures, as in a right ventricular heart attack, the approach flips. The right ventricle may actually need more fluid volume to maintain enough forward flow, at least temporarily. Medications that strengthen heart contractions can also help bridge the gap while the muscle recovers.
Maintaining a normal heart rhythm matters in right heart failure more than people expect. The right ventricle is thinner-walled and more dependent on well-timed atrial contractions to fill properly. If an irregular rhythm like atrial fibrillation develops, it can significantly worsen symptoms regardless of whether the underlying problem is systolic or diastolic.
The Bottom Line on Classification
Right-sided heart failure is not inherently systolic or diastolic. It spans both categories. The right ventricle can lose pumping strength, lose its ability to relax and fill, or both. What determines the type is the underlying cause: muscle damage tends to produce systolic failure, while pressure overload and restrictive conditions tend to start as diastolic failure before potentially progressing to include systolic dysfunction. In clinical practice, more than half of patients with heart failure already show measurable right ventricular diastolic abnormalities, making the diastolic component extremely common even when systolic function still looks preserved.