Patient Preparation
- Before scheduling the patient ask for his/her weight. MPI can be performed safely and accurately in obese patients, the only limit is the capacity of the spect table. Check the manual or engineer advise for maximal load.
- Fasting for 3-4 h previous to stress test it is recommended, to conduct the procedure at baseline condition. It also be useful to limit gastrointestinal activity adjacente to the heart. This direction is necessary before the resting spect acquisition as well.
- Withdraw cardiovascular medications only if indicated by attending physician. In particular betablockers in case of exercise procedure. Allow 5 plasma half lives to pass on each of the pharmaceutical.
- When employing dipyridamole or adenosine (preferred if LBBB or use of betablockers is present) withdraw any food containing xanthines (tea, coffee, chocolate, beverages) for 12 h - 24 h. They block adenosine receptors and thus limit the pharmaceutical actions. If it is suspected the need to switch exercise test to a pharmacologic one this preparation is recommended as well.
- Adjust protocol for CAD diagnosis (stress-rest) or viability assessment (rest).
- To increase tracer myocardial uptake especially when looking for viability, the use of 5-10 mg isosorbide mononitrate sublingually is suggested 10 min before injecting the radiotracer for the resting phase. Alternatively 5 mg sublingual nitroglycerin can be employed. It must be used cautiously in patients on erectile dysfunction medication, those with severe anemia and in cases with aortic stenosis or other preload-dependant cardiac pathologies. Likewise, if the resting viability phase follows stress with dypiridamole. In all these cases, keep patient supine for 30 min after the final acquisition, check blood pressure and allow the patient to shift to the standing position gradually, in order to prevent fainting.
References:
1 Mut F. Diagnostico de la Enfermedad Coronaria and Gonzalez P et al. Viabilidad Miocardica, in Medicina Nuclear Aplicaciones Clínicas. Ignasi Carrio y Patricio González . Editorial Masson, Barcelona España, 2003, p 39-56 and 105-119, respectively.
2 DeCicco AE et al. Feasibility of SPECT myocardial perfusion imaging in the super-obese using a multi-head semiconductor camera with attenuation correction. J Nucl Cardiol. 2015 Apr;22(2):344-50.
3 Dorbala S, Crugnale S, Yang D, Di Carli MF. Effect of body mass index on left ventricular cavity size and ejection fraction. Am J Cardiol. 2006 Mar 1;97(5):725-9.
Home Index Myocardial Perfusion Spect Mibi Myocardial Perfusion Spect Study Protocol