The popularity recently achieved by balloon angioplasty of coronary arteries is limited by the risk of reocclusion of the stenotic segment addressed. Sudden reocclusion leads frequently to an acute coronary syndrome (acute myocardial infarction, hypotension, arrhythmias) that requires emergency surgery and also leads to permanent myocardial damage of various degrees. Preliminary data has recently become available to suggest that prolonged balloon inflations could be an important tool in attaining optimal early and late results of angioplasty. These considerations have resulted in renewed interest in peripheral coronary perfusion during balloon coronary angioplasty. The most critical limiting factor to the distal perfusion of blood is the inner lumen of the balloon catheters, which are relatively small. We present laboratory data regarding the pressure/flow ratios of different balloon catheters.