ABC | Volume 114, Nº2, February 2020

Update Update of the Brazilian Guideline on Nuclear Cardiology – 2020 Arq Bras Cardiol. 2020; 114(2):325-429 Table 11 – Adverse effects or “paraeffects” related to intravenous administration of dipyridamole for performance of myocardial perfusion scintigraphy 24,46 Adverse effects or paraeffects % Chest pain 20 Headache 12 Dizziness 12 Alterations in ST 8 Ventricular extrasystoles 5 Nausea 5 Arterial hypotension 5 Facial flushing 3 Atrioventricular blockage 2 Fatal or non-fatal myocardial infarction Extremely rare Any minor event 50 Table 12 – Adverse effects or “paraeffects” related to intravenous adenosine administration via infusion pump for performance of myocardial perfusion scintigraphy 24,46 Adverse effects or paraeffects % Facial flushing 35 to 40 Chest pain 25 to 30 Shortness of breath 20 Dizziness 7 Nausea 5 Symptoms of hypotension 5 Atrioventricular blockage 8 Alterations in ST 5 – 7 Atrial fibrillation Case reports Convulsions Case reports Hemorrhagic/ischemic stroke Case reports Any minor event 80 Table 13 – Contraindications to use of adenosine and dipyridamole 24,46 Absolute • Bronchospastic disease during activity, recent hyperreactivity (< 3 months), status asthmaticus • Second- or third-degree atrioventricular blockage, in the absence of a pacemaker • Arterial hypotension (systolic blood pressure less than 90 mmHg) • Recent transient ischemic attack or cerebrovascular accident (< 2 months) • Recent use (less than 24 hours) of dipyridamole in patients who are to receive adenosine Relative • History of reactive pulmonary disease, with no recent crises (> 3 months) • Sinus node disease • Severe sinus bradycardia • Severe bilateral carotid disease respectively. The most commonly used is dobutamine , which acts on beta-1 ( β -1) adrenergic receptors, with chronotropic and inotropic stimulation, depending on the infused dose, in addition to direct effects on beta-2 ( β -2) receptors, with peripheral vasodilation response. This results in an increase in cardiac output, HR, and SBP, leading to an increase in MVO 2 and, consequently, in coronary vasodilation. Protocol: The protocol begins with venous administration of the solution (250 mg of dobutamine diluted in 250 ml of saline solution - 1 mg per 1 ml) via infusion pump at a dose of 10 ug.kg -1 . min -1 for 3 minutes (first step), followed by 20 μg.kg -1 .min -1 for 3 minutes (second step), adding 10 μg.kg -1 .min -1 every 3 minutes (third and fourth steps) until the maximum dose of 40 μg.kg -1 .min -1 has been reached (Figure 6). 73,74 In patients who have not reached submaximal HR and who do not have evidence of ischemia, it is possible to associate intravenous atropine (0.25 to 2 mg) and perform isometric stress with hand grip maneuvers (e.g., compressing a tennis ball). A Brazilian study has demonstrated that early use of atropine (following the first phase of dobutamine infusion) is safe and that it reduces infusion time and complaints during stress, without affecting diagnostic precision. 75 Furthermore, the presence of perfusion defects induced by pharmacological vasodilatation and motility abnormalities triggered by stress aggregate incremental prognostic value to the test, which has recently been validated with the use of ultrarapid cameras (CZT technology). 76 Contraindications to dobutamine use may be found in Table 14. Patients on betablockers should stop taking these medications for 48 to 72 hours before the test. Special attention should be given to patients with bronchospasm undergoing MPS with dobutamine, whose plasma half-life is around 2 to 3 minutes, considering that its antagonist is metoprolol at an intravenous dose of 5 mg and that it is contraindicated in the presence of pulmonary obstructive disease. The most frequent adverse events or paraeffects associated with administration of dobutamine solution are listed in Table 15. To reverse them, in addition to metoprolol, other intravenous short-acting betablockers, such as esmolol (0.5 mg.kg ), which is available, should be injected after the first minute of radiotracer injection. Combined stress: The association of dynamic stress with low workloads (e.g., until the second stage of the Bruce protocol or until feeling light fatigue , equivalent to the number 13 on the subjective Borg stress scale) and vasodilators has been shown to reduce subdiaphragmatic (hepatic) activity and improve the ratio of radiation activity emitted between the target organ and the viscera (background), with consequent improvements in image quality. 77 It has similarly shown a decrease in the occurrence of adverse effects resulting from the infusion of dipyridamole or adenosine, as well as the incidence of atrioventricular blockage. This protocol is ideal for patients who are able to 342