Jie Zhang PhD, Presenter: Research grant, Siemens AG

Joel Garland Fletcher MD, Abstract Co-Author: Research grant, Siemens AG Instructor, E-Z-EM, Inc License agreement, General Electric Company

Philip Alexander Araoz MD, Abstract Co-Author: Nothing to Disclose

Eric E. Williamson MD, Abstract Co-Author: Consultant, General Electric Company

Andrew Primak PhD, Abstract Co-Author: Research grant, Siemens AG

Cynthia H. McCollough PhD, Abstract Co-Author: Research grant, Siemens AG Research grant, General Electric Company

W. Scott Harmsen MS, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

To determine the heart rate and heart rate variation during cardiac CT examinations, and to determine the influence of contrast media injection, age and gender on heart rate and heart rate variation.

We analyzed ECG data from 101 patients (60 male, 41 female; mean age: 59.1 ± 14.3 years) undergoing contrast-enhanced CT coronary angiography (CTA) alone or non-contrast coronary artery calcium scanning (CAC) followed by CTA in the same examination (57 of 101). All exams were done on a Siemens Sensation 64 scanner. Eleven patients with atrial fibrillation were excluded from the analysis. The patients with heart rate >70 bpm were pre-treated with oral beta-blockers and all patients received sub-lingual nitroglycerin, per our routine clinical protocol. The patients were divided into two age groups according to the median age (63.5 years). Mean heart rate and heart rate variation (the percent of heart beats outside the mean rate ± a 5 bpm region) were computed and compared for each of three time intervals: baseline (free breathing), pre-scan hyperventilation, and scan acquisition (breath-hold).

Mean heart rate during CTA (59.2± 8.7 bpm) and CAC (58.2± 8.5 bpm) during scanning (breath-holding) was significantly lower than at baseline (free-breathing) (62.8± 8.9 bpm), P0.05. For 52 patients undergoing both CTA and CAC, the injection of contrast media (CTA vs. CAC) had no significant effect on either heart rate (59.0 bpm vs. 58.2 bpm) or heart rate variation (4.0% vs. 3.0 % outside of interval mean ± 5 bpm), P>0.05. No difference was found between gender and age groups, P>0.05.

Breath-holding during cardiac CT scan acquisition significantly lowers the mean heart rate by approx.. 4 bpm, but doesn’t change heart rate variation compared to normal breathing.

For cardiac CT acquisitions of 10-15 seconds, the injection of contrast media, age and gender have negligible impact on heart rate and its variation.

Zhang, J, Fletcher, J, Araoz, P, Williamson, E, Primak, A, McCollough, C, Harmsen, W, et al, , Analysis of Heart Rate and Heart Rate Variation during Cardiac CT Examinations.  Radiological Society of North America 2006 Scientific Assembly and Annual Meeting, November 26 - December 1, 2006 ,Chicago IL. http://archive.rsna.org/2006/4438471.html