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Am J Physiol Heart Circ Physiol 295: H2054-H2060, 2008. First published September 12, 2008; doi:10.1152/ajpheart.91400.2007
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Increased diastolic time fraction as beneficial adjunct of {alpha}1-adrenergic receptor blockade after percutaneous coronary intervention

Christina Kolyva,1 Bart-Jan Verhoeff,2 Jos A. E. Spaan,1 Jan J. Piek,2 and Maria Siebes1,2

Departments of 1Biomedical Engineering & Physics and 2Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands

Submitted 4 December 2007 ; accepted in final form 11 September 2008

The effect of {alpha}1-receptor blockade with urapidil on coronary blood flow and left ventricular function has been attributed to relief of diffuse coronary vasoconstriction following percutaneous coronary intervention (PCI). We hypothesized that an increase in diastolic time fraction (DTF) contributes to the beneficial action of urapidil. In eleven patients with a 63% (SD 13) diameter stenosis, ECG, aortic pressure (Pa) and distal intracoronary pressure (Pd), and blood flow velocity were recorded at baseline and throughout adenosine-induced hyperemia. Measurements were obtained before and after PCI and after subsequent {alpha}1-receptor blockade with urapidil (10 mg ic). DTF was determined from the ECG and the Pa waveform. Functional parameters such as coronary flow velocity reserve, fractional flow reserve, and an index of hyperemic microvascular resistance (HMR) were assessed. Urapidil administration after PCI induced an upward shift in the DTF-heart rate relationship, resulting in a 3.1% (SD 2.7) increase in hyperemic DTF at a constant heart rate (P < 0.005) due to a shorter duration of systole. Hyperemic Pa and Pd decreased, respectively, by 6.1% (SD 6.6; P < 0.05) and 5.7% (SD 5.8; P < 0.01) after {alpha}1-blockade. Although epicardially measured functional parameters were on average not altered by {alpha}1-blockade due to concurrent changes in pressure and heart rate, HMR decreased by urapidil in those patients where coronary pressure remained constant. In conclusion, {alpha}1-receptor blockade after PCI produced a modest but significant prolongation of DTF at a given heart rate, thereby providing an adjunctive beneficial mechanism for improving subendocardial perfusion, which critically depends on DTF.

coronary circulation; angioplasty; microcirculation; diastole; {alpha}-adrenergic receptors


Address for reprint requests and other correspondence: M. Siebes, Dept. of Biomedical Engineering & Physics, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands (e-mail: m.siebes{at}amc.uva.nl)






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