washout phenomenon
Rapid clearance of contrast agent from vessel segments, often indicating competitive flow or vascular steal.
Full Definition
The washout phenomenon describes the abnormally rapid clearance or disappearance of contrast agent from specific vessel segments during angiographic imaging. This finding typically indicates the presence of competitive flow from collateral vessels, arterial steal phenomena, or high-flow arteriovenous connections. In coronary intervention, washout may be observed in scenarios where bypass grafts compete with native vessel flow, or in the presence of significant collateral circulation. Recognition of this phenomenon is important for assessing vessel viability, determining the functional significance of stenoses, and understanding hemodynamic relationships between different vascular territories.
Usage
Usage note: Use as single compound noun; distinguish from slow-flow or no-flow phenomena which have different implications.
In Context
- "Angiography demonstrated washout phenomenon in the RCA due to robust collateral flow." — Angiographic interpretation
- "The washout phenomenon suggested competitive flow from the patent bypass graft." — Post-surgical assessment