Chronic elevation of pulmonary vascular resistance increases the workload imposed on the right ventricle. The ventricle responds with structural remodeling, including hypertrophy, which raises its measured weight relative to the left ventricle and septum. Consequently, a higher Fulton Index reflects a stronger anatomical response to sustained pressure overload and can indicate more advanced right-sided cardiac remodeling.
The denominator combines the weights of the left ventricle and interventricular septum, creating a reference against which right ventricular weight is evaluated. This expresses right ventricular enlargement as a ratio rather than as an isolated weight. Interpretation therefore focuses on the relative prominence of right ventricular remodeling, helping relate cardiac structural change to disease severity.
The Fulton Index is an anatomical indicator, whereas pulmonary vascular resistance describes the pressure-related burden within the pulmonary circulation. The ratio does not directly measure vascular resistance; instead, it records the right ventricle’s structural response to that burden. This distinction makes the index useful for assessing remodeling, but it should be interpreted as an indirect measure of pressure-overload effects.
After the heart is dissected, the right ventricle is separated and weighed, while the left ventricle and interventricular septum are weighed together. The right ventricular weight is then divided by the combined left ventricular and septal weight. This calculation produces the ratio used to evaluate the extent of right ventricular hypertrophy in the specimen.
The measurement is useful when investigators need to assess right ventricular remodeling in patients, autopsy specimens, or experimental models. It supports evaluation of pathological cardiac changes associated with chronic pressure overload and can also be used to examine disease severity. In treatment studies, changes in the ratio help assess whether an intervention alters structural remodeling.
A higher ratio indicates greater right ventricular remodeling and provides a measurable anatomical outcome for comparison. Researchers can use it to characterize pathological changes, compare the severity of pressure-overload effects, or evaluate treatment responses across specimens and experimental groups. The index therefore connects cardiac structure with the progression or modification of disease-related changes.