Evaluación de la sincronización ventricular por análisis de fase de Fourier en una ventriculografía radioisotópica / Evaluation of ventricular synchronization by Fourier phase analysis in a radionuclide ventriculography

Introducción: La ventriculografía radioisotópica (VRI) permite la evaluación de la contractilidad global y segmentaria, así como la detección de trastornos de conducción. Objetivo: Se realizó el análisis de fase del tercer armónico de Fourier en una VRI con el propósito de evaluar los parámetros temporales de la sincronización ventricular en el corazón normal e introducir esta técnica en nuestro centro. Material y Métodos: Se incluyeron 30 individuos normales (19 hombres y 11 mujeres). A todos se les realizó una VRI en equilibrio en proyección oblicua anterior izquierda de 35 grados con 10 grados de angulación caudal. En el histograma del tercer armónico de Fourier de la curva actividad-tiempo se midieron: el tiempo de inicio (T0); el tiempo medio (Tm); el tiempo total (Tt); el tiempo final (Tf) y el tiempo de propagación (Tp) para cada ventrículo; así como el tiempo total de propagación (TTP); el tiempo de conducción interventricular (TVD-VI) y el tiempo de conducción septum-pared lateral (TS-PL).Resultados: El ventrículo derecho comienza a contraerse 5 ms antes que el izquierdo (T0VD = 66 ñ 38 ms; T0VI = 71 ñ 30 ms), con un tiempo de contracción total ligeramente mayor (TtVD = 67 ñ 28 ms vs TtVI = 64 ñ 38 ms). El tiempo total de propagación (TTP) fue de 69 ñ 37 ms y el tiempo interventricular (TVD-VI) fue 2 ñ 25 ms. La contracción progresó de septum a pared lateral, con un tiempo septum-pared lateral (TS-PL) de 4 ñ 22 ms. Conclusión: A través del análisis de fase en una ventriculografía radioisotópica puede cuantificarse la contracción simultánea de ambos ventrículos, lo que proporciona un instrumento que pudiera resultar de utilidad para la evaluación de la resincronización ventricular en la estimulación multisitio (AU)

Enhanced detection of reversible myocardial hypoperfusion by technetium 99m-tetrofosmin imaging and first-pass radionuclide angiography after nitroglycerin administration.

BACKGROUND: Reversal of ischemia after myocardial infarction by revascularization is worthwhile only if viability exists in a sufficiently large portion of the left ventricle. METHODS AND RESULTS: To determine myocardial hypoperfusion reversibility and its influence on segmental and global function, we studied 50 patients after myocardial infarction. Three technetium 99m-tetrofosmin scintigraphies were performed: 1 at rest, 1 after 0.6 mg sublingual nitroglycerin (NTG), and 1 after injection at peak stress. First-pass multigated radionuclide angiography was obtained at rest and after NTG. Each patient also underwent a stress redistribution-reinjection thallium-201 scintigraphy. During stress 99mTc-tetrofosmin, 104 segments had normal uptake, 51 showed moderately reduced uptake, and 186 had severely reduced uptake. Of these 186 segments, 33 (18%) improved at rest, and 41 (22%) improved only after NTG. Fifty-nine (79%) of these segments with improved uptake were also found to have reversible defects on 201TI imaging. In the 26 patients with ventricular dysfunction, a 73% agreement was found between the functional and 99mTc-tetrofosmin uptake post-NTG improvement, whereas a 69% agreement was found with thallium reinjection. No significant differences were seen between 99mTc-tetrofosmin and 201T1 imaging. CONCLUSION: Nitroglycerin administration during 99mTc-tetrofosmin scintigraphy improves the detection of myocardium with reversible hypoperfusion in patients with a previous myocardial infarction.

Radionuclide ventriculography in dynamic cardiomyoplasty.

Dynamic cardiomyoplasty improves ventricular function by increasing pump function and by limiting cardiac dilatation. The aim of this study was to assess long-term myocardial performance by radionuclide ventriculography on dilated cardiomyopathy patients subjected to cardiomyoplasty. Thirteen survivors were included. Radionuclide ventriculography was performed one week before surgery and one year later. Five patients were also studied two years following surgery. The left ventricular ejection fraction (LVEF), end-diastolic volume (EDV) and ventricular amplitude ratio (VAR) to assess mitral regurgitation were measured. Every case after one year showed a non-significant increase in LVEF. However, the decrease in EDV and in VAR was significant (p < 0.01). No significant difference in these values was found after two years. We conclude that the effects of cardiomyoplasty--reduction of cardiac dilatation, wall stress and mitral regurgitation--are more evident during the first year after surgery. Thereafter, a certain stabilization is observed.