Time to maximal vasodilator effect of intracoronary nitroglycerin administration in coronary angiography

Author(s): Sanitpong Fongjunsom

Background: Nitroglycerin (NTG) is frequently used to evaluate coronary vessel size from coronary angiography (CAG). However, the timing of the maximal vasodilatory effect of NTG while performing CAG is not well established. This study aims to determine the timing of the maximal vasodilatory effect of intracoronary NTG (IC NTG) administration.

Methods: This prospective study enrolled 40 consecutive patients scheduled for CAG and/or Percutaneous Coronary Intervention (PCI) in Surin hospital. Cineangiography was done and recorded as a baseline. Thereafter, 200 mcg of NTG was injected via the catheter. Interval cineangiography at 30, 60, 90, 120, and 150 seconds was performed. Hemodynamics was recorded throughout the procedure. Coronary artery size was measured by the Quantitative Coronary Analysis (QCA) method. Calibration was made by using a catheter as a reference. Measurement was done in optimal view for each part of the vessel and the frame to be measured was selected from the same phase of cardiac cycle in each patient.

Results: Coronary artery diameter was significantly increased with IC NTG. The mean time for a maximal change was 101.25 ± 31.95 seconds. The maximal increase in vessel size was 0.36 mm. (95% CI 0.29, 0.43 p<0.001). Mean aortic pressure significantly decreased after IC NTG. Mean time for maximal change of Mean Aortic Pressure (MAP) was 63.75 ± 41.99 seconds. The maximal decreased of MAP was -14.08 mmHg (95% CI-17.22, -10.93).

Conclusion: In PCI naïve coronary artery, A 200 mcg IC NTG reaching maximal vasodilatory effect around 2 minutes. MAP was significantly reduced but without clinical significance.