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Coronary Wave Intensity in Humans: Effect of Changes in Microvascular Resistance by Vasodilation and Stent Placement, and Changes in Heart Rate
Author(s) -
Kolyva Christina,
Verhoeff BartJan,
Piek Jan J.,
Spaan Jos A. E.,
Siebes Maria
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.a1396
Wave intensity (WI) analysis separates upstream from downstream traveling wavefronts. It is uniquely suited to study the coronary microcirculation, where a backward compression wave (BCW) is generated by cardiac contraction during early systole. We applied WI analysis for the first time in human coronary arteries and hypothesized that the magnitude of BCW depends on coronary microvascular resistance (MR) and cardiac contractility. ECG, aortic pressure (Pa), and distal coronary pressure (Pd) and flow velocity (v) were recorded at rest and maximal hyperemia in 26 patients before and after stent placement, and in 9 patients at sinus rhythm and during atrial pacing at 120 bpm. Rate pressure product (RPP = sysPa x HR) was used to estimate contractility. WI was computed as (dPd/dt) x (dv/dt) and MR = Pd/v. The area under the BCW was compared to MR and RPP by paired t‐tests. BCW increased proportionately to a fall in MR (p<0.001) with vasodilation at constant RPP. Stenting restored hyperemic Pd (from 63±3 to 87±3 mmHg, p<0.001) and further reduced minimal MR by 32% (p<0.002), while BCW increased by 126% (p<0.001). A 76% rise in RPP (p<0.001) caused a 279% rise in BCW at rest (p<0.001) and a 20% decline in baseline MR (p<0.01), while during hyperemia BCW rose by 19% although minimal MR increased by 24% (p<0.05). We conclude that the magnitude of BCW is inversely related to coronary MR at constant RPP, verifying the pressure‐dependence of minimal MR in humans. BCW also strongly depends on RPP via cardiac contractile force. (Support: NHF grant 2000.090)