Title: Perfusion imaging by PET to assess stenosis significance
Abstract: Quantification of coronary flow and coronary flow reserve is an attractive concept to assess stenosis significance, because the ultimate severity of a coronary stenosis depends on the reduced ability to increase myocardial blood flow by reserve vasodilation at the arteriolar level [1]. By arteriolar autoregulation coronary flow reserve follows the myocardial demand, in other words, coronary circulation remains at a constant level with either decreased coronary pressure or increased stenosis severity to meet the actual metabolic demand (Figure 1). Nevertheless, the quantitative magnitude of vasodilator flow reserve is inversely related to the increasing severity of a stenosis. The complexity of this concept of coronary flow reserve is outlined in Figure 2. The autoregulatory capacity allows resting coronary blood flow to stay constant over a wide range of diameter stenoses but decreases gradually with a stenotic diameter reduction of 85% to 90%, and is reduced under resting conditions with diameter stenoses >90%. This relationship is the basic concept of coronary flow reserve measurements for defining stenosis severity (Figure 2). In normal arteries coronary flow can be increased 3 to 5 times by vasodilation of the periphereal coronary bed, thus absolute coronary flow reserve, defined as maximal flow in the stenosed artery devided by resting blood flow in the same region, ranges from 3 to 5 in humans. With increasing stenosis severity coronary flow reserve decreases almost linearly and in severely stenosed arteries with exhausted coronary reserve, maximal vasodilation does not even result in any flow increase; hence, absolute coronary flow reserve has the minimal value of one.
Publication Year: 1996
Publication Date: 1996-01-01
Language: en
Type: book-chapter
Indexed In: ['crossref']
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