Induced right-to-left cardiac shunt during pulmonary perfusion imaging

Area of Science:

• Nuclear medicine
• Cardiopulmonary diagnostics
• Radiopharmacology

Background:

• Ventilation-perfusion (V/Q) lung scans utilize Tc-99m MAA particles for pulmonary imaging.
• Right-to-left shunts can lead to systemic activity on V/Q scans.
• Hypoxemia and increased venous return can exacerbate right-to-left shunting.

Observation:

• The study involved maneuvers to intentionally increase right-to-left shunting.
• These maneuvers were employed during a V/Q scan.
• Systemic activity was observed, consistent with shunting.

Findings:

• The maneuvers successfully demonstrated and quantified right-to-left shunting.
• The findings indicated the presence of fixed pulmonary hypertension.
• The patient's exertional dyspnea was attributed to pulmonary hypertension, not left ventricular dysfunction.

Implications:

• This diagnostic approach can differentiate causes of dyspnea.
• It aids in identifying fixed pulmonary hypertension.
• Management strategies can be tailored based on these findings, potentially deferring interventions like coronary bypass surgery.