What Causes Right Ventricular Hypertrophy
Right ventricular hypertrophy develops primarily from increased afterload due to pulmonary hypertension (from any cause), left-sided heart failure, pulmonary vascular disease, congenital heart lesions, valvular pathologies, and primary cardiomyopathies affecting the right ventricle 1.
Primary Mechanisms of RV Hypertrophy
The right ventricle hypertrophies as an adaptive response to pressure overload. The key causative pathways include:
Pressure Overload Conditions
- Pulmonary arterial hypertension - This is the most common driver of RV hypertrophy, where increased pulmonary vascular resistance forces the RV to generate higher systolic pressures 1, 2
- Pulmonary embolism - Acute increases in RV afterload from large PE can trigger hypertrophic responses 1
- Pulmonic stenosis - Direct obstruction to RV outflow 1
- Chronic obstructive pulmonary disease - Leading to cor pulmonale 1
Left Heart Disease
- Heart failure with reduced ejection fraction (HFrEF) - RV hypertrophy occurs secondary to postcapillary pulmonary hypertension from elevated left-sided filling pressures 1
- Left ventricular dysfunction - Transmits backward pressure into the pulmonary circulation 1
Volume Overload
Systemic Hypertension
- Biventricular hypertrophy - RV hypertrophy occurs in 17-80% of hypertensive patients (average 28.6%), often paralleling left ventricular hypertrophy through mechanisms including elevated LV filling pressures transmitted to pulmonary circulation, ventricular interdependence, and systemic circulation of growth factors like angiotensin II and aldosterone 3, 4
Primary Myocardial Disease
- Hypertrophic cardiomyopathy - RV hypertrophy occurs in approximately 25-33% of HCM patients, associated with worse biventricular mechanics and increased heart failure hospitalizations 5, 6
- Myocarditis - Direct inflammatory injury 1
- RV myocardial infarction - Ischemic injury 1
Adaptive vs. Maladaptive Hypertrophy
A critical distinction exists between compensated (adaptive) and decompensated (maladaptive) RV hypertrophy 7, 8:
Adaptive Hypertrophy
- Concentric hypertrophy with preserved RV systolic function
- Maintained RV-pulmonary artery coupling
- Better functional capacity and survival
- Typically occurs with pure pressure overload
Maladaptive Hypertrophy
- RV dilation, fibrosis, and failure
- Impaired angiogenesis, adrenergic signaling, and metabolism
- Metabolic shift to aerobic glycolysis (similar to cancer cells)
- Capillary rarefaction leading to RV ischemia
- Occurs when pressure overload is combined with myocardial injury or ischemia 2, 8
Pathophysiologic Progression
The hypertrophied RV initially develops isovolumic contraction and relaxation phases with increased systolic pressure and end-diastolic volume. As decompensation occurs, pulmonary vascular resistance and right atrial pressure rise concomitantly. Declining pulmonary artery pressure in the setting of high pulmonary vascular resistance is an ominous finding indicating advanced RV failure 1.
Clinical Pitfalls
- RV dilation eventually compresses the LV cavity through ventricular interdependence, impairing LV filling and equalizing biventricular diastolic pressures—this mechanism, rather than reduced RV forward output, is the primary cause of reduced cardiac output in chronic RV failure 1
- RV fibrosis initially protects against pressure overload-induced dilation but eventually becomes excessive and impairs cardiac function 9
- The prevalence of RV dysfunction is higher in nonischemic dilated cardiomyopathy compared to ischemic cardiomyopathy, possibly due to genetic predisposition 1