Viable myocardium scintigraphy with intravenous nitroglycerine by computed tomography with Tc-99m (MIBI).
BACKGROUND
The selection of patients with chronic coronary disease for recanalization is based on the detection of the affected myocardium that is potentially viable.


OBJECTIVE
To evaluate the potentially viable ischemic myocardium through single photon emission computed tomography (SPECT) with MIBI after a maximum tolerated dose of I.V. nitroglycerin.


METHODS
We prospectively investigated by SPECT with Tc-99m (MIBI), from April 2004 to November 2005, 40 patients (mean age: 62 +/- 8.9 yrs, 30 men) with coronary obstruction demonstrated angiographically; the myocardium scintigraphy was carried out at rest and after intravenous (I.V.) nitroglycerin, which was started at a dose of 1 microg/kg/min and increased every minute until the systolic blood pressure decreased by 20 mmHg. The decrease in the perfusion of the segments was classified as moderate or severe and compared after the nitroglycerin. The angiographic, hemodynamic and myocardial perfusion variables were analyzed.


RESULTS
We analyzed 680 myocardial segments at rest: 538 with a homogenous distribution and 142 with hypoperfusion (54 with moderate and 88 with severe decrease). After the nitroglycerin, there was an increase in the perfusion in 19 (47.5%) of 40 patients and 55 of 142 segments became viable: 33 (61.1%) with moderate and 22 (25%) with severe decrease; both presented a significant increase in the radiotracer distribution (p < 0.001, Chi-square).


CONCLUSIONS
One of the components with Tc-99m is Tc-99m 2-methoxy-isobutyl-isonitrile (MIBI), which, when used with an optimized dose of I.V. nitroglycerin, can increase the radiotracer uptake in areas with moderate and severe hypoperfusion. The results of the present study suggest the increase in the Tc-99m (MIBI) sensitivity by nitroglycerin for the detection of viable myocardium.
Universidade São Francisco, Bragança Paulista, SP, Brasil. joseramos@cardiol.br
José
J
Ramos Filho
Marcos Welber
MW
Nascimento
Rafael Mariano Gislon da
RM
Silva
Thiago Negrini de
TN
Camargo
Roberto Simões de
RS
Almeida
Eloá Jacinto
EJ
Lima
D000328:Adult; D000368:Aged; D001794:Blood Pressure / Q000502:physiology; D016009:Chi-Square Distribution; D003326:Coronary Circulation / Q000502:physiology; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007275:Injections, Intravenous; D008297:Male; D020714:Maximum Tolerated Dose; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005996:Nitroglycerin / Q000008:administration & dosage; D011446:Prospective Studies; D019275:Radiopharmaceuticals; D012146:Rest; D017256:Technetium Tc 99m Sestamibi; D013997:Time Factors; D015899:Tomography, Emission-Computed, Single-Photon; D014665:Vasodilator Agents / Q000008:administration & dosage
D019275:Radiopharmaceuticals; D014665:Vasodilator Agents; D017256:Technetium Tc 99m Sestamibi; D005996:Nitroglycerin