Right heart strain (RHS) is a medical finding indicating that the right side of the heart is working against abnormally high resistance or pressure. The right ventricle is a thin-walled, crescent-shaped chamber that pumps deoxygenated blood into the lungs through the pulmonary circulation. When pressure within the pulmonary arteries becomes too high, the right ventricle struggles to push blood forward. This excessive workload stresses the right ventricular muscle, resulting in strain. Right heart strain signals a significant underlying problem affecting the lungs or the heart’s circulatory system.
Understanding Right Heart Strain
Right heart strain is a physiological response by the right ventricle to an increased workload, driven by elevated pressures in the pulmonary arteries. This increased resistance against which the ventricle must pump is known as increased afterload. The right ventricle is structurally less robust than the left ventricle and is less able to tolerate a sudden rise in afterload.
The strain manifests in two primary anatomical ways: dilation and hypertrophy. Dilation occurs when the ventricle stretches and enlarges to accommodate the increased volume or pressure. Hypertrophy is the thickening of the muscular wall as the heart attempts to generate more force to overcome the resistance. In acute, severe cases, the sudden pressure overload causes rapid dilation and dysfunction, often without time for compensatory hypertrophy.
When the right ventricle dilates, the central wall separating it from the left ventricle, the interventricular septum, can bow inward toward the left side. This mechanical effect impairs the filling and function of the left ventricle, leading to reduced overall cardiac output. The failure to pump efficiently results in blood backing up into the venous system, causing the physical manifestations of strain.
Underlying Conditions Causing Overload
Conditions causing right heart strain are categorized by whether the onset of pressure overload is sudden (acute) or develops over time (chronic). The most common acute cause is a massive pulmonary embolism (PE), where blood clots migrate to the lung arteries and physically block blood flow. This sudden obstruction instantly increases the resistance (afterload) against which the right ventricle must pump, often leading to rapid failure.
Chronic causes involve long-term diseases that slowly raise pressure in the pulmonary circulation. Pulmonary hypertension is characterized by abnormally high blood pressure in the arteries of the lungs, forcing the right ventricle to work constantly. Chronic lung diseases, such as severe Chronic Obstructive Pulmonary Disease (COPD) and interstitial lung disease, lead to low oxygen levels and destruction of the lung’s vascular bed, subsequently increasing pulmonary pressure.
Left-sided heart failure is also a major chronic cause, as the failing left ventricle causes blood to back up into the lungs. This congestion increases pressure within the pulmonary veins and capillaries, transmitting that elevated pressure to the right ventricle. Over time, the sustained high pressure leads to progressive remodeling and strain of the right heart muscle.
Recognizing the Physical Symptoms
When the right ventricle can no longer efficiently pump blood to the lungs, pressure builds up, and blood backs up into the systemic veins. This systemic venous congestion causes the most recognizable physical symptoms of right heart strain. A common symptom is peripheral edema, presenting as noticeable swelling, particularly in the lower extremities like the ankles, feet, and legs.
Patients often experience shortness of breath (dyspnea), which worsens with physical activity as the strained right ventricle is unable to meet the body’s increased oxygen demands. Fatigue and exercise intolerance are frequent complaints due to the heart’s reduced ability to maintain adequate blood flow and oxygen delivery.
Another specific sign is jugular venous distension (JVD), the visible bulging of the jugular veins in the neck, reflecting the elevated pressure within the central venous system. The backup of blood can also cause congestion in the abdominal organs, leading to abdominal discomfort, pain in the upper right quadrant due to liver swelling, and a feeling of fullness.
Diagnostic Procedures for Confirmation
Confirmation of right heart strain requires imaging and physiological testing to visualize the heart’s structure and assess its function.
The transthoracic echocardiogram (Echo) is the primary non-invasive tool, providing detailed images of the right ventricle’s size and performance. Findings include an enlarged right ventricle compared to the left, abnormal motion of the interventricular septum, or decreased overall contractility.
The electrocardiogram (ECG or EKG) provides electrical evidence of strain, particularly T-wave inversions in leads viewing the right ventricle, reflecting muscle stress or lack of oxygen supply. In acute cases like pulmonary embolism, the ECG may show a new right bundle branch block or the specific S1Q3T3 pattern.
Computed Tomography Pulmonary Angiography (CTPA) is a specialized CT scan used to definitively diagnose acute causes like pulmonary embolism by visualizing blockages. CTPA also allows clinicians to assess the degree of right ventricular enlargement, helping determine strain severity. Blood tests, including cardiac biomarkers like B-type Natriuretic Peptide (BNP) and troponin, are utilized, as elevated levels reflect myocardial wall stress and injury.