RATIONALE AND OBJECTIVES. The degree to which pulmonary angiography may contribute to serious complications in patients with pulmonary hypertension has not been clarified and remains a matter of debate. Accordingly, this study was designed (1) to detect the potential release of vasoactive peptides and (2) to investigate the hemodynamic response after administration of a nonionic contrast medium in patients with pulmonary hypertension undergoing pulmonary angiography. Allergy-mediating substances also were measured to monitor for possible anaphylactoid reactions. METHODS. Pulmonary digital subtraction angiography was performed in 20 patients with pulmonary hypertension (mean pulmonary arterial pressure more than 20 mm Hg). Iopromide was administered as a total of 100 mL via a 7F catheter inserted from the right femoral vein. The injected volume and duration of injection (15 to 20 mL/sec) were kept constant. Hemodynamic parameters were continuously monitored, including electrocardiogram, heart rate, phasic and mean pulmonary arterial and peripheral arterial pressures. Blood samples were obtained before and after administration of contrast media to assay for the concentration of the following vasoactive peptides using radioimmunoassay techniques: renin, angiotensin-I-converting enzyme, angiotensin II, aldosterone, atrial natriuretic peptide, antidiuretic hormone, cyclic-guanosine monophosphate, and myoglobin, as well as allergy-mediating substances such as tryptase, eosinophil protein X, and eosinophil cationic protein. RESULTS. Administration of iopromide caused significant increases in atrial natriuretic peptide (from 61.3 ± 11.8 to 94.0 ± 16.7) and antidiuretic hormone (from 6.6 ± 1.9 to 12.3 ± 3.1), whereas renin significantly decreased (from 3.0 ± 0.6 to 1.3 + 0.5). After administration of contrast media, there were no significant changes in the other measured vasoactive peptides, allergy-mediating substances, and monitored cardiovascular parameters. CONCLUSION. Administration of iopromide for pulmonary angiography in patients with pulmonary hypertension resulted in no appreciable hemodynamic alterations associated with the observed changes in atrial natriuretic peptide, antidiuretic hormone, and renin. No allergy-mediated reactions were observed in these patients.
The effect of a new intravascular magnetic resonance (MR) contrast medium (gadolinium diethylenetriaminepentaacetic acid [DTPA] polylysine) was evaluated in acute, subacute, and chronic myocardial infarctions in rats. Signal intensity (SI) was measured before and after intravenous administration of Gd-DTPA polylysine. Before administration of contrast material, chronic infarctions had lower SI than normal myocardium. With Gd-DTPA polylysine, three zones were identified in acute and subacute stages of myocardial infarction, but in the chronic stage, images demonstrated two zones. In acute and subacute infarctions, Gd-DTPA polylysine produced greater enhancement (over 60 minutes) in the peri-infarction zone than in the normal or infarcted myocardium. In chronic infarctions, Gd-DTPA polylysine had no discernible effect on the SI of the central infarction zone. Overall, it caused no significant hemodynamic effects. MR imaging with Gd-DTPA polylysine produced differential tissue enhancement in myocardial infarctions, which varied according to the age of the infarction.
RATIONALE AND OBJECTIVES. This study compared the areas demarcated by a T1-enhancing agent, Gd-DTPA-BMA, and a magnetic susceptibility agent, Dy-DTPA-BMA, with 201thallium autoradiography (indicator of perfusion) and postmortem histochemical staining with triphenyltetrazolium chloride (TTC)(indicator of infarction). METHODS. Thirteen rats were subjected to coronary artery occlusion for 3 to 4 hours before acquisition of four sets of electrocardiogram-gated spin-echo magnetic resonance (MR) images: T1-weighted images before and after 0.2 mmol/kg Gd-DTPA-BMA; and T2-weighted images before and after 0.3 mmol/kg Dy-DTPA-BMA. After MR imaging, intravenous 201thallium delineated the area of decreased myocardial perfusion. At autopsy, TTC staining delineated the area of myocardial infarction. RESULTS. A myocardial region in the distribution of the occluded artery was delineated as a hyperintense area ("hotspot") by Dy-DTPA-BMA and as a hypointense area ("coldspot") by Gd-DTPA-BMA. The hyperintense area demarcated by Dy-DTPA-BMA (51 ± 3% of the area of the midequitorial slice of the left ventricle) showed a closer relationship to the area of decreased myocardial perfusion (jeopardized area) (46 ± 3%), determined by 201thallium autoradiography, than the area of myocardial infarction (36 ± 4%), determined by histochemical staining. However, the hypointense area demarcated by Gd-DTPA-BMA (29 ± 2%) did not relate as closely to the area of decreased myocardial perfusion (slope = 0.54) or the area of myocardial infarction (r = 0.46). CONCLUSIONS. The abnormal myocardial area delineated by the magnetic susceptibility agent showed a closer relationship to the area of deficient myocardial perfusion (jeopardy area) after coronary occlusion than that defined by T1-enhancing contrast media.
RATIONALE AND OBJECTIVES. Gadolinium-ethoxybenzyl-DTPA (Gd-EOB–DTPA) is a recently introduced experimental magnetic resonance (MR) contrast agent for hepatic imaging. Although liver enhancement has been investigated in a number of animal models, tolerance evaluations of Gd-EOB–DTPA injection have been limited. METHODS. The authors investigated acute hepatotoxicity in an isolated perfused rat liver model, cardiovascular effects in the anesthetized rat, and potential immunogenicity of Gd-EOB–DTPA using detection of specific antibodies. RESULTS. Using perfused rat liver model, no significant deviation could be observed for functional parameters, liver enzymes, or potassium release, comparing Gd-EOB-DTPA to a control, but there was a significant choleresis (+250% bile flow). Hemodynamic effects of Gd-EOB–DTPA were observed after femoral bolus injection, but only with relatively high dosages (0.3—0.5 mmol/kg, 10-fold the likely clinical dose in humans). Experimental conditions, idealized for antibody induction, failed to cause an IgG immune response to Gd-EOB–DTPA in the intact rat. CONCLUSIONS. The results further support preliminary conclusions that Gd–EOB–DTPA is a well-tolerated MR contrast agent.
Abstract The purpose of this study was to compare a new MR macromolecular contrast medium (MMCM), gadolinium‐diethylenetriamine pentaacetic acid (Gd‐DTPA)‐24‐cascade‐polymer, to a well‐studied prototype MMCM, for the potential of distinguishing tissues of varying endothelial permeability. Three tissue models of varying capillary permeability were studied in a total of 46 rats: normal myocardium (normal capillaries), subcutaneously implanted adenocarcinoma (mild capillary leak), and reperfused infarcted myocardium (high capillary leak). T1‐weighted MRI was performed before and dynamically after injection of either albumin‐(Gd‐DTPA) 30 or the cascade polymer (each .02 mmol gadolinium [Gd] per kg). Data analysis based on a two‐compartment kinetic model yielded estimates of fractional blood volume (BV) (percentage) and fractional leak rate (FLR) (1 per hour). Permeability to the cascade polymer as reflected in FLR was considerable in normal myocardium (8.24 per hour), of similar value in tumors (8.55 per hour), but significantly greater in infarcted myocardium (39.17 per hour, P < .01) versus normal myocardium. The larger albumin‐(Gd‐DTPA) 30 demonstrated minimal extravasation in normal myocardium (FLR .33 per hour); FLR in tumors was 100% higher (.66 per hour, P < .002) and FLR in reperfused capillaries was significantly greater (7.94 per hour, P < .001). Based on capillary permeability measurements, the cascade polymer may have limited utility for detection of mildly increased microvascular permeabilities. For severe tissue injury, the cascade polymer can resolve abnormal microvascular integrity.
