RESUMEN
BACKGROUND/AIM: In patients with acute central retinal vein occlusion (CRVO), dynamic angiography may reveal the presence of pulsatile flow (termed here pulsatile venular outflow, PVO) within first order veins (that is, the large veins). The main goal of this study was to investigate the mechanism underlying PVO. METHODS: 10 patients with CRVO and PVO were included. Quantitative and qualitative analysis of venous flow on dynamic angiograms allowed the correlation, temporally, of second and first order vein flow on the one hand, and venous flow and systolic cycle on the other. RESULTS: Analysis of the time-velocity curve showed that (1) the onset of arterial systole preceded the onset of PVO by less than 0.08 seconds (n = 5); (2) PVO onset was simultaneous to the time of onset of minimal flow (Vmin) in first order veins (n = 10); (3) the time of onset of maximal flow (Vmax) in first order veins occurred 0.20-0.44 seconds after the onset of PVO (n = 6). CONCLUSIONS: During CRVO with severe reduction in blood flow, the presence of PVO is the result of the existence of a distinct haemodynamic regimen in first and second order veins. These data support the hypothesis that second order veins flow is synchronous with the arterial flow, while the delayed peak flow in first order veins may reflect the consequences of the delayed IOP curve and/or of intermittent venous compression.
Asunto(s)
Flujo Pulsátil , Oclusión de la Vena Retiniana/diagnóstico , Enfermedad Aguda , Adulto , Anciano , Angiografía/métodos , Velocidad del Flujo Sanguíneo , Colorantes , Femenino , Humanos , Procesamiento de Imagen Asistido por Computador/métodos , Verde de Indocianina , Masculino , Persona de Mediana Edad , Oftalmoscopía , Pronóstico , Estudios Prospectivos , Flujo Sanguíneo Regional , Oclusión de la Vena Retiniana/fisiopatología , Arterias Temporales/diagnóstico por imagen , Ultrasonografía DopplerRESUMEN
The aim of the study was to analyze ECG (QRS) voltage responses to body fluid shift due to gravity chances. Acute changes in gravity were created by two ways: 1) changes in gravity value during parabolic flights (within 27 subjects 45 ECG have been analyzed); 2) changes in gravity direction due to rotation of the body during postural tests (within 11 subjects 14 ECG have been analyzed). Results and conclusions. Gravity change leads to body fluid shift and changes of intrathoracic organs and tissues electroconduction. It influences on ECG voltage. During parabolic flights in up-right position: R amplitude in Z axis increases in hypergravity (+0.19 mV) and decreases in microgravity (-0.24 mV). During postural tests, R amplitude in Z axis increases in orthostatic position (+0.09 mV) and decreases in antiorthostatic position (-0.025 mV). Changes in QRS voltage during parabolic flights are more important than during postural tests. This could be due to more effective blood redistribution during parabolic flights.
Asunto(s)
Electrocardiografía , Transferencias de Fluidos Corporales/fisiología , Vuelo Espacial , Simulación de Ingravidez , Ingravidez , Adulto , Femenino , Humanos , Hipergravedad , Presión Negativa de la Región Corporal Inferior , Masculino , Persona de Mediana Edad , Postura/fisiología , Rotación , Posición Supina/fisiología , Tórax/irrigación sanguínea , Tórax/fisiologíaRESUMEN
The effects of a beta-blocker, celiprolol, on sleep and arterial blood pressure (BP) were evaluated during a single-blind study in seven hypertensive patients with sleep apnea. Diurnal ambulatory BP measurements with an automatic cuff-inflation device and polysomnography with simultaneous Finapres BP recording were performed separately on consecutive days at the end of two 21-day treatment periods involving placebo followed by celiprolol (200 mg/day). Age was 59 +/- 2.5 yr (m +/- sem) and body mass index 33.2 +/- 2.3 kg. m-2. Diurnal ambulatory BP was significantly lower with celiprolol than with placebo (systolic 139 +/- 4 vs 152 +/- 5 mmHg, diastolic 86 +/- 2 vs 96 +/- 2 mmHg). The apnea-hypopnea index was similar under celiprolol and placebo (48 +/- 7.4 vs 53 +/- 7.8, respectively), as were the total sleep time and percent of duration of the different sleep stages. Individual average BP values were significantly lower during REM sleep under celiprolol but remained similar under celiprolol and placebo in the other sleep stages. Variability of nocturnal BP (assessed by the SD of distribution of BP variations) was not affected by celiprolol. In conclusion, celiprolol which decreased daytime BP, did not affect sleep pattern or respiratory disturbances, or nocturnal BP variability related to apnea.