RESUMEN
Visual assessment of intravascular ultrasound (IVUS) video images cannot reliably identify thrombus. We examined if texture analysis of radiofrequency (r.f.) data or videodensitometric data (VD) could distinguish thrombi of different ages and cell compositions. Whole human blood (red clot = RC), platelet-rich plasma (white clot = WC) and plasma (n = 6/group) were imaged at 4 and 24 h with 30 MHz IVUS transducers. At 4 h, VD- and r.f.-based analyses revealed significant differences between RC and WC with variance (VD red 26.4 +/- 2.5, white 33.9 +/- 7.8; r.f. red 1.4 +/- 0.5, white 4.9 +/- 1.3), kurtosis (VD red 0.29 +/- 0.9, white 0.23 +/- 0.3) and skewness (VD red 0.23 +/- 0.13, white 0.35 +/- 0.52; r.f. red 0.06 +/- 0.01, white -0.06 +/- 0.05). Also mean grey-level from both data sets was higher in RC (VD 134.8 +/- 18.0; r.f. -13.3 +/- 1.2) than in WC (VD 105.3 +/- 17.4, r.f. 16.5 +/- 2.2) (p < 0.01). With increasing time, variance increased in WC (5.5 +/- 1.5 at 24 h) and decreased in RC (0.9 +/- 0.3.3 at 24 h). The more heterogeneous structure of WC may be distinguished from that of RC using texture analysis of either VD or r.f.-signals.
Asunto(s)
Procesamiento de Imagen Asistido por Computador , Procesamiento de Señales Asistido por Computador , Hexafluoruro de Azufre , Trombosis/diagnóstico por imagen , Ultrasonografía Intervencional/métodos , Coagulación Sanguínea , Trombosis Coronaria/diagnóstico por imagen , Densitometría/métodos , Humanos , Factores de TiempoRESUMEN
Raw 30-MHz intravascular ultrasound data have been captured from postmortem coronary arteries (n = 4) to develop radio frequency analysis techniques for the characterisation of atherosclerotic plaque. Digitised data acquired from positions (n = 8) within diseased sections of artery were compared with the corresponding histology and radiology. Scan-converted images were used to locate regions of interest (ROI = 33) within areas of tissue composition: loose fibrotic tissue (LFT), dense fibrotic tissue (DFT) and calcium (CA). A range of parameters was extracted from the normalised power spectrum of each ROI within the bandwidth 17-42 MHz. Significant discrimination between LFT/DFT and between LFT/CA was provided by maximum power and spectral slope (dBMHz-1). However, the greatest discriminative power was given by the y-axis (0 Hz) intercept of the spectral slope: LFT/DFT (p = 0.001); LFT/CA (p = 0.0001); and DFT/CA (p = 0.089).
Asunto(s)
Enfermedad de la Arteria Coronaria/diagnóstico por imagen , Vasos Coronarios/diagnóstico por imagen , Ultrasonografía Intervencional , Enfermedad de la Arteria Coronaria/patología , Vasos Coronarios/patología , Humanos , Procesamiento de Imagen Asistido por Computador , Técnicas In Vitro , Procesamiento de Señales Asistido por ComputadorRESUMEN
Doppler myocardial imaging (DMI) is a new ultrasound imaging modality in which colour Doppler algorithms are adapted to visualise the myocardium. It allows measurement of regional intramyocardial velocities and quantification of intramural left ventricular function. However promising the technique is, to date the accuracy of endocardial boundary detection by DMI has not been validated. As Doppler velocity estimation is based on measurement of phase shift rather than signal strength, the technique is relatively independent of chest wall attenuation. In the current study, a series of in vitro and in vivo studies was performed to compare standard B-mode grey-scale imaging (GSI) and DMI techniques in endocardial boundary detection. In vitro, the minimum and maximum volumes of a single-chamber tissue-mimicking phantom were calculated using both imaging techniques. In vivo, left ventricular end-diastolic (ED) volume and end-systolic (ES) volume indices were measured from GSI and DMI images in a group of 40 volunteers. All images were obtained in the freeze-frame mode with the Doppler display turned on and off so that simultaneous DMI and GSI information was obtained. In vitro, the limits of agreement between the minimum volume of the phantom and the minimum volume measured by GSI and DMI was 4% and 3%, respectively. For maximum volumes, limits of agreement were 3% for GSI and 2% for DMI. In vivo, the limits of agreement between the two imaging techniques in volume measurements were 6 mL (9%) for ED and 4 mL (11%) for ES. The comparison of the endocardial boundary detection by GSI vs. DMI showed DMI to be significantly superior: ED (72 +/- 16% vs. 85 +/- 8%, respectively; p < 0.05) and ES (71 +/- 13% vs. 88 +/- 7%, respectively; p < 0.05). The results of the study show that: (1) in vitro, based on two-dimensional algorithms, DMI provides as accurate volume measurements as GSI; and (2) in vivo, there is a very good agreement of left ventricular volume measurements between GSI and DMI. However, the endocardial boundary is more reliably displayed and visually easier to detect using DMI than GSI.
Asunto(s)
Ecocardiografía Doppler , Ecocardiografía , Endocardio/diagnóstico por imagen , Adulto , Femenino , Humanos , MasculinoRESUMEN
Nonuniform rotation of mechanical intravascular ultrasound transducers may give rise to a geometric distortion of the ultrasound image known as the rotation angle artefact. This investigation studied the influence of different degrees and combinations of catheter shaft angulation on image morphology and the quantitative impact of the artefact using a circular perspex phantom and 3.5 F, 30 MHz Boston Scientific "Sonicath" catheters connected to a Hewlett Packard Sonos intravascular scanner. Major and minor diameters, cross-sectional area and circumference of the phantom lumen were measured and a "distortion index" calculated. Visually apparent geometric distortion was graded from 1 (absent) to 4 (severe). As expected, eccentric transducer location was associated much more frequently with identifiable distortion (70%) than was a concentric location (6%). Greater distortion occurred with increasing degrees of catheter shaft angulation, and was more pronounced in images from older catheters. The lumen area measurements in images in which no artefact was identified were accurate to within +/- 10% in 97% of cases, compared to only 81% of cases when an artefact was noted. The quantitative accuracy of an image in which geometric distortion is identified is thus not reliable. The direction of the quantitative error cannot be confidently predicted in any given case, although the mean lumen area tends to increase as the grade of distortion increases.
Asunto(s)
Cateterismo , Ultrasonografía Intervencional/métodos , Artefactos , Modelos Biológicos , Fantasmas de Imagen , RotaciónRESUMEN
Intravascular ultrasound is widely used to guide coronary stent implantation. The key quantitative criterion for successful implantation is the demonstration of adequate expansion of the stented lumen relative to that of the adjacent reference vessel segments. In this study we aimed to establish the reproducibility of intravascular ultrasound measurements of the reference segments in lesions undergoing coronary stenting. Measurements of the reference segment lumen dimensions warn made in a blinded fashion by two experienced observers, and reproducibility was assessed by calculating the mean difference and standard deviation of the paired measurements. The unselected intraobserver random variability of the mean reference lumen area measured 0.6 mm2. The interobserver random variability was 0.94 mm2. The intraobserver and interobserver variability of minimum lumen area within the stent was smaller, measuring 0.30 mm2 and 0.52 mm2, respectively. There was 91% intraobserver agreement, and 75% interobserver agreement, in identifying adequate stent expansion as defined by a stent-to-mean reference lumen area ratio of > 0.8. The potentially significant level of variability inherent in selecting and measuring the reference segments, and its impact on clinical decision-making, should be remembered when this method of assessing the acute quantitative outcome of stent implantation is applied.
Asunto(s)
Angioplastia Coronaria con Balón/instrumentación , Enfermedad Coronaria/terapia , Vasos Coronarios/diagnóstico por imagen , Monitoreo Intraoperatorio/instrumentación , Ultrasonografía Intervencional , Angioplastia Coronaria con Balón/métodos , Vasos Coronarios/anatomía & histología , Estudios de Evaluación como Asunto , Humanos , Monitoreo Intraoperatorio/métodos , Variaciones Dependientes del Observador , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , StentsRESUMEN
Pathological cardiovascular manifestations are reported in four male patients, who had taken massive amounts of anabolic steroids while undergoing many years of strength training. One patient was referred because of ventricular fibrillation during exercise, one because of clinically manifest heart failure, and one because of arterial thrombus in his lower left leg. The fourth patient was persuaded to attend for a check-up because of a long history of massive use of anabolic steroids. All four patients had cardiac hypertrophy. Two of the patients had symptoms and signs of heart failure, and one of these two had a massive thrombosis in both right and left ventricles of his heart. After cessation of the use of anabolic steroids in the other patient with heart failure, left ventricular wall thickness reduced quickly from 12 to 10.5 mm, and fractional shortening increased from 14% to 27%. Endomyocardial biopsy revealed increased fibrosis in the myocardium in two of the three cases. HDL-cholesterol was 0.58 mmol.l-1 and 0.35 mmol.l-1 in the two patients still using multiple anabolic steroids at the time of investigation. The cardiovascular findings described in the present paper should warn all physicians and athletes about the possible serious acute and long-term side effects of the massive use of anabolic steroids.
Asunto(s)
Anabolizantes/efectos adversos , Enfermedades Cardiovasculares/inducido químicamente , Levantamiento de Peso , Adulto , Anabolizantes/administración & dosificación , Biopsia , Enfermedades Cardiovasculares/diagnóstico , Relación Dosis-Respuesta a Droga , Electrocardiografía/efectos de los fármacos , Endocardio/patología , Fibrosis Endomiocárdica/inducido químicamente , Fibrosis Endomiocárdica/diagnóstico , Fibrosis Endomiocárdica/patología , Prueba de Esfuerzo/efectos de los fármacos , Insuficiencia Cardíaca/inducido químicamente , Insuficiencia Cardíaca/diagnóstico , Insuficiencia Cardíaca/patología , Ventrículos Cardíacos/patología , Humanos , Hipertrofia Ventricular Izquierda/inducido químicamente , Hipertrofia Ventricular Izquierda/diagnóstico , Hipertrofia Ventricular Izquierda/patología , Masculino , Miocardio/patología , Taquicardia Ventricular/inducido químicamente , Taquicardia Ventricular/diagnóstico , Taquicardia Ventricular/patología , Trombosis/inducido químicamente , Trombosis/diagnóstico , Trombosis/patologíaRESUMEN
The ability of digitalis compounds to counteract calcium antagonist overdose was studied in anesthetized dogs (n = 6, 13.5 +/- 0.7 kg) and isolated trabeculae from human hearts (n = 7). Digitalis caused by increasing intracellular cytosolic Ca2+ concentration through Na+/Ca(2+)-exchange across the cell membrane, was postulated to overcome the detrimental effects of excessive slow calcium-channel blockade. In anesthetized dogs, an infusion of verapamil (40 mg/30 min, i.v.) decreased mean arterial pressure from 88 +/- 6 to 66 +/- 6 mm Hg (P < 0.05), reduced systemic vascular resistance (SVR) from 3838 +/- 916 to 2200 +/- 669 dyne.s/cm5 (P < 0.05), and induced total atrio-ventricular (A-V) block in three animals. Stroke volume (SV) remained unchanged. Administration (i.v.) of NaCl (0.9%, 200 ml) and calcium gluconate (100 mg)--to increase the availability of Na+ and Ca(2+)--together with atropine (0.2 mg)--to block the parasympathetic effects of digoxin on A-V conduction--increased left ventricular contractility (15%) but had no significant effects on blood pressure, SV, or A-V block. Digoxin (0.125 mg) returned sinus rhythm in all dogs and, by increasing SVR (P < 0.05) and left ventricular contractility (P < 0.05), returned arterial pressures to baseline. Because of increased afterload, SV decreased slightly (15%) despite increased cardiac contractility. In experiments with isolated trabeculae from diseased human hearts, TA 3090 (Clentiazem) depressed contractile force and ouabain, another glycoside, restored contractile force within 30 min.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Atropina/uso terapéutico , Digoxina/uso terapéutico , Miocardio/metabolismo , Verapamilo/envenenamiento , Animales , Calcio/metabolismo , Bloqueadores de los Canales de Calcio/envenenamiento , Gluconato de Calcio/uso terapéutico , Depresión Química , Diltiazem/análogos & derivados , Diltiazem/envenenamiento , Perros , Sobredosis de Droga , Electrocardiografía , Femenino , Hemodinámica/efectos de los fármacos , Humanos , MasculinoRESUMEN
The effects of amlodipine, a novel, long-lasting calcium channel blocking agent, on ischemia-induced myocardial conduction delay was studied in anesthetized pigs paced at a constant heart rate. Acute coronary occlusion (3 minutes) significantly lengthened time to onset, time to peak and duration of bipolar electrograms recorded from both subendocardial and subepicardial left ventricular sites. After intravenous injection of amlodipine (0.3 mg/kg, n = 6), subsequent periods of ischemia greatly reduced (p less than 0.01) all indexes of subepicardial conduction delay. In the subendocardium, amlodipine decreased only time to onset (-25 +/- 4%, p less than 0.01) within the ischemic zone. Significant delays in all indexes were present during repeated ischemic periods in the placebo-treated control group (n = 5). Amlodipine also increased regional myocardial blood flow within the nonischemic myocardium by 25 +/- 10% and decreased mean aortic pressure by 7 +/- 2% without altering flow in the ischemic region. Left atrial pressure remained unchanged. Indexes of ischemia-induced conduction delay were more rapidly restored after reperfusion in amlodipine-pretreated than in control animals. In conclusion, amlodipine produced a beneficial blood flow-independent effect on ischemia-induced injury potentials. The effect may help to reduce the likelihood of development of lethal ventricular arrhythmias in the early stage of myocardial ischemia in the clinical setting.
Asunto(s)
Enfermedad Coronaria/tratamiento farmacológico , Sistema de Conducción Cardíaco/efectos de los fármacos , Corazón/efectos de los fármacos , Amlodipino , Animales , Presión Sanguínea/efectos de los fármacos , Bloqueadores de los Canales de Calcio , Enfermedad Coronaria/fisiopatología , Electrofisiología , Corazón/fisiopatología , Sistema de Conducción Cardíaco/fisiopatología , Ventrículos Cardíacos , Nifedipino/farmacología , Reperfusión , Porcinos , Factores de TiempoRESUMEN
The haemodynamic effects of endurance training with or without anabolic steroid treatment (nandrolone decanoate, 5.0 mg kg-1 week-1) were studied before and after a six-week sedentary period in anaesthetized, open-chest rats during isoproterenol and CaCl2 loads. In comparison to the control group (CG I, n = 13) endurance training (TG I, n = 10) increased the resting stroke index significantly, end-diastolic pressure and during CaCl2 infusion the end-diastolic and end-systolic volumes. Peripheral resistance decreased in TG I during both inotropic loads but increased in CG I (P less than 0.01 between the groups). After combined endurance training and anabolic steroid treatment (TSG I, n = 16) the haemodynamic state was similar to that in CG I except peripheral resistance which was even higher than in CG I. The heart weight to body weight ratio was significantly greater both in TG I and TSG I than in CG I. After a six-week deconditioning period the haemodynamic values were essentially similar in endurance trained (TG II, n = 10) and in control rats (CG II, n = 12). After the sedentary period, in the simultaneously trained and anabolic steroid-treated group (TSG II, n = 13) stroke index and end-diastolic volume decreased more during isoproterenol load when compared with TG II or CG II (P less than 0.05 between the groups). Peripheral resistance was higher in the TSG II than in the two other groups. In conclusion, the enhanced pumping performance of the heart by increased left ventricular diastolic filling after endurance training is attenuated by simultaneous anabolic steroid treatment which further increases the peripheral resistance. Detraining reversed the main training effects in six weeks and simultaneous anabolic steroid treatment led to a decreased left ventricular filling and to elevated peripheral resistance after the sedentary period.
Asunto(s)
Anabolizantes/administración & dosificación , Hemodinámica/efectos de los fármacos , Resistencia Física/efectos de los fármacos , Animales , Peso Corporal/efectos de los fármacos , Corazón/anatomía & histología , Isoproterenol/administración & dosificación , Masculino , Tamaño de los Órganos/efectos de los fármacos , Esfuerzo Físico , Ratas , Ratas Endogámicas , Factores de TiempoRESUMEN
The haemodynamic effects of endurance training and physical deconditioning were studied in anaesthetized rats using aortic and left ventricular pressure recordings and volume measurements by thermodilution method during isoproterenol and CaCl2 loads. The resting stroke volume was significantly larger in the training group (TG I, n = 10) than in the control group (CG I, n = 13). During the CaCl2 infusion stroke index, end-diastolic and end-systolic volumes increased in the TG I, but decreased in the CG I. Both isoproterenol and CaCl2 decreased systemic vascular resistance in the TG I, but increased it in the CG I. After a six-week deconditioning following training period (TG II, n = 10) stroke index, end-diastolic and end-systolic volumes decreased during CaCl2 and isoproterenol infusions similarly to the control deconditioning group (CG II, n = 12). These responses differed significantly from those observed in the TG I. Peripheral resistance increased in both the CG II and the TG II. Cardiac hypertrophy observed during training was partly reversed after the deconditioning period. In conclusion, endurance training improves the pumping performance of the rat heart by enhancing the diastolic filling of the left ventricle and decreasing peripheral resistance during inotropic load. Left ventricular contractility is not affected. A six-week deconditioning period after endurance training returns the haemodynamic changes to sedentary levels.