Final answer:
The next step after a negative bubble study for a patient with isolated RV enlargement and elevated RVSP is further evaluation for pulmonary hypertension causes, which includes pulmonary function tests, high-resolution chest CT, and possibly a right heart catheterization.
Step-by-step explanation:
When a young person presents with isolated RV (right ventricular) enlargement and elevated RVSP (right ventricular systolic pressure), with a negative bubble study, this indicates that there is no intracardiac shunt. The next step typically involves determining the cause of the pulmonary hypertension and right heart strain. Clinically, it is important to assess the patient for other signs or symptoms of pulmonary hypertension such as shortness of breath, fatigue, chest pain, or syncope. Part of this evaluation should also include a thorough risk factor assessment for pulmonary arterial hypertension (PAH).
Diagnostic steps often include additional non-invasive studies such as pulmonary function tests, high-resolution chest CT to evaluate lung parenchyma, evaluation for sleep-disordered breathing, and V/Q scan to rule out chronic thromboembolic pulmonary hypertension (CTEPH). If non-invasive studies do not reveal the cause, a right heart catheterization may be necessary to measure pulmonary artery pressures directly and to assess the pulmonary vascular resistance and cardiac output, which can further guide the diagnosis and treatment.