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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hemodynamic changes due to intracoronary injections of nonionic contrast medium Omnipaque-350 (OM), ionic dimer Hexabrix (HB), and ionic contrast medium Renografin-76 (R76) were compared at baseline and during reperfusion after a 30-minute left anterior descending coronary artery (LAD) occlusion. In 11 open chest, anesthetized, and atrially paced dogs, 4 ml of either OM, HB, R76, or 0.9% NaCl were injected into the carotid-LAD bypass system. Coronary blood flow (CBF) and coronary vascular resistance (CVR) were measured before, during and after the intracoronary injection. The maximal hyperemic change (in percentage) from the preinjection value of CBF and CVR were calculated. The results at baseline and during reperfusion for CBF were: 104 +/- 14% vs. 85 +/- 10% for OM (NS); 76 +/- 11% vs. 39 +/- 9% for R76 (p less than 0.05); 57 +/- 8% vs. 33 +/- 5% for HB (P less than 0.05); and 30 +/- 7% vs. 9 +/- 4% for 0.9% NaCl (p less than 0.05). Consequently, the hyperemic changes of CVR at baseline and during reperfusion were: -49 +/- 3 vs. -42 +/- 4% for OM (NS); -44 +/- 3% vs. -24 +/- 6% for R76 (p less than 0.01); -36 +/- 3% vs. -24 +/- 4% for HB (p less than 0.05); and -18 +/- 4% vs. -7 +/- 3% for 0.9% NaCl (p less than 0.05). Thus, ischemia and reperfusion significantly dampened the coronary hemodynamic and vascular response to R76, HB, and 0.9% NaCl but not to OM. The preserved coronary vascular reserve with high flow in this canine post-ischemic reperfusion model may explain the advantage of nonionic over ionic contrast media used in emergency coronary angiography following thrombolysis.
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PMID:Effects of intracoronary administration of contrast media on coronary hemodynamics in a canine post ischemic reperfusion model. 207 Apr 5

The influence on contractile force (CF) and the propensity for ventricular fibrillation (VF) from infusing the non-ionic contrast medium iohexol during normal (75 cm H2O) and reduced perfusion pressure (35 cm H2O) were investigated in the isolated rabbit heart. Both during normal and reduced perfusion pressure iohexol (150 mg I/ml) with oxygen saturation caused a smaller reduction of CF than iohexol without oxygen. During reduced pressure iohexol with sodium addition (28 mM NaCl) caused less depression of CF than iohexol without sodium. The combination of sodium addition and oxygen saturation had the least influence on CF. Iohexol (350 mg I/ml) without sodium had a similar fibrillatory propensity during both normal and reduced pressure. Enriching iohexol with 28 mM NaCl decreased the risk of VF. The decrease was similar during both normal and reduced pressure. The risk of VF from oxygen saturation of iohexol (350 mg I/ml, without sodium) was similar during both normal and reduced pressure. It is concluded that a small addition of sodium and/or oxygen saturation of a non-ionic monomeric contrast medium have beneficial effects on the heart both during normal perfusion pressure and during ischemia.
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PMID:Sodium addition and/or oxygen saturation of iohexol during normal and reduced perfusion pressure. Effects on contractile force and risk of ventricular fibrillation in the isolated rabbit heart. 226 4

In this study the attention was focused on the possible application of the new low-osmolar water-soluble contrast media in already existing routines for radiologic diagnostic work-up and management of the abdominal emergencies of simple intestinal obstruction and ischemia: Iohexol was a good, or better, alternative to sodium diatrizoate regarding taste acceptance and patient reactions: Seventy-five per cent of patients characterized the taste of iohexol as good or neutral, while 52% gave sodium diatrizoate similar scores. The scores were also consistently in favor of iohexol as compared with sodium diatrizoate for the other chosen criteria; nausea, vomiting and diarrhea, but a larger number of patients may be needed for conclusive evaluation. Water-soluble media may have therapeutic effects on intestinal obstruction when preceded by conventional gastric suction using a short gastric tube: Twenty-three of 25 patients with subtotal small bowel obstruction due to peritoneal adhesions improved following the ingestion of either iohexol or sodium diatrizoate. Hyperosmolar contrast media might stimulate peristalsis and dilute the bowel contents, hence, easing the passage through a subtotally obstructed bowel. In rats, a direct relationship was found between contrast medium osmolality and the degree of intestinal distension, fluid influx to the bowel lumen and the speed of contrast medium progression. The water-soluble, low-osmolar contrast media seem promising as diagnostic aids in examination of the gastrointestinal tract: The low-osmolar contrast media gave better intestinal details on films than both barium sulphate and sodium diatrizoate in rats with intestinal obstruction or ischemia when high volumes of radiopaques were employed. Also in patients iohexol retained its radiographic density in the small bowel better than sodium diatrizoate. The diagnostic efficacy of the water-soluble radiographic media varied directly with their osmolality and the resulting fluid influx to bowel lumen. Hyperosmolality stimulated contrast medium progression and bowel distension, and reduced the radiographic density of the contrast media and the alignment to the bowel wall. Water-soluble contrast media may aid the diagnosis of bowel ischemia and the evaluation of the degree of ischemic injury: No bladder opacification, following absorption of water-soluble contrast media from the simply obstructed bowel, was observed in the majority of the animals and was only faintly present in 8%. Distinct radiographic opacification of the urinary bladder in rats with intestinal ischemia was demonstrated as early as 1-2 hours after the administration of contrast medium.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Water-soluble contrast media in obstructed in ischemic small intestine. A clinical and experimental study. 264 49

Clinical studies have shown pulmonary and right ventricular hypertension to be important factors increasing the risk to patients during pulmonary angiography. This experiment was undertaken to define the hemodynamic changes induced by the administration of contrast material into the pulmonary arteries of dogs with embolic pulmonary hypertension, and to compare the effects of ionic and nonionic agents. Ten closed-chest dogs under light halothan anesthesia were subjected to pulmonary embolization with sephadex microspheres until severe pulmonary hypertension occurred and the cardiac output decreased to 50%-60% of the pre-embolization baseline. Intra-pulmonary injections of contrast material were performed in eight animals while hemodynamic indices were measured. Sodium methylglucamine diatrizoate induced severe, transient, hypotension associated with a large decrease in systemic vascular resistance and little change in the cardiac output. Hypotension is especially undesirable in the presence of pulmonary hypertension because it worsens the preexisting coronary ischemia and compromised right ventricular function. No elevation in mean pulmonary artery pressure was seen, and pulmonary vascular resistance decreased. Iohexol induced milder effects, perhaps because it exerts a less severe systemic vasodilatory effect and is not a negative inotrope. These findings suggest iohexol may be safer in the high risk patient, however, these data may not be directly applied to unanesthetized humans.
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PMID:The hemodynamic effects of the administration of ionic and nonionic contrast materials into the pulmonary arteries of a canine model of acute pulmonary hypertension. 337 76

This study evaluates the use of iohexol as a radiographic diagnostic contrast agent in normal animals and those with experimental bowel ischemia and obstruction. Eighteen rats and 12 rabbits were gavaged with iohexol in a dose of 7.5 mL/kg using concentrations of 140 mg I/mL (isotonic with blood) or 300 mg I/mL. In addition, four rabbits had intraperitoneal iohexol injection and three were given gastrografin gavage. Experimental groups included normal bowel controls, bowel injury induced by ischemia and alcohol contact, bowel obstruction by ligature, and intraperitoneal injection. Serial abdominal radiographs and plasma concentrations of iohexol were obtained. Iohexol remained stable throughout the gastrointestinal tract, retained its intensity, and was well visualized up to four days after administration. Bowel images were fair at concentrations of 140 mg I/mL and excellent at 300 mg I/mL. Gastrografin caused bowel distention and poor visualization related to dilution. It also precipitated in the stomach. Iohexol was rapidly absorbed from the peritoneal cavity and excreted by the kidneys, without causing peritonitis. Rat plasma iohexol levels were three times controls in obstructed bowel and 80 times controls if there was mucosal injury without perforation. Rabbit peak plasma levels were 30 times greater following intraperitoneal injection than with gastric gavage. These observations suggest that iohexol may be useful as a gastrointestinal contrast agent. Measuring plasma iohexol levels may be helpful in the evaluation of suspected bowel ischemia or perforation in the clinical setting.
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PMID:Use of iohexol in the radiographic diagnosis of ischemic bowel. 372 5

This study aimed to assess the potential of 64-slice MDCT in characterizing revascularized infarcted myocardium at the cellular and microvascular levels. Pigs (n = 7) underwent 2 h left anterior descending coronary artery occlusion/reperfusion. In acute (2-4 h) and subacute (1 week) infarction, first-pass perfusion (FPP) (1 ml/kg of 300 mg/ml Omnipaque) was performed using a cine (rotation time 60 s/bpm) non-ECG gated sequence (mAS/kV = 100/120). Delayed contrast enhanced images (DE) (mAS/kV = 650/120) were acquired every 2 min for 10 min to determine the kinetics of Omnipaque and to define infarcted myocardium and microvascular impairment (representing microvascular obstruction and/or no- or low-reflow phenomenon). Maximum upslope, maximum attenuation and time to the peak were measured from FPP plots. 2,3,5-Triphenyltetrazolium-chloride (TTC) was used to define true infarction in the excised hearts. Hyperenhanced myocardium on DE was measured and compared with TTC. The contrast media caused minor beam hardening and X-ray scatter on FPP. The above-mentioned perfusion parameters significantly differed between remote and acute infarction. Infarcted myocardium showed two patterns of enhancement on DE, hyperenhanced rim representing the perfused infarction and hypoenhanced core representing a microvascular impaired region, with significantly different attenuation. The extent of infarction on DE-MDCT decreased over the course of 1 week and did not differ from TTC. Post-processed FPP semi-quantitative images showed a decline in myocardial blood volume and flow in acute revascularized infarction. In conclusion, modern MDCT has the potential to identify residual ischemia on FPP and microvascular impairment and infarction on DE images.
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PMID:Identification of residual ischemia, infarction, and microvascular impairment in revascularized myocardial infarction using 64-slice MDCT. 1897 14

We aim to demonstrate the application of free-breathing prospectively gated carbon nanotube (CNT) micro-CT by evaluating a myocardial infarction model with a delayed contrast enhancement technique. Evaluation of murine cardiac models using micro-CT imaging has historically been limited by extreme imaging requirements. Newly-developed CNT-based x-ray sources offer precise temporal resolution, allowing elimination of physiological motion through prospective gating. Using free-breathing, cardiac-gated CNT micro-CT, a myocardial infarction model can be studied non-invasively and with high resolution. Myocardial infarction was induced in eight male C57BL/6 mice aged 8-12 weeks. The ischemia reperfusion model was achieved by surgically occluding the LAD artery for 30 minutes followed by 24 hours of reperfusion. Tail vein catheters were placed for contrast administration. Iohexol 300 mgI/mL was administered followed by images obtained in diastole. Iodinated lipid blood pool contrast agent was then administered, followed with images at systole and diastole. Respiratory and cardiac signals were monitored externally and used to gate the scans of free-breathing subjects. Seven control animals were scanned using the same imaging protocol. After imaging, the heart was harvested, cut into 1mm slices and stained with TTC. Post-processing analysis was performed using ITK-Snap and MATLAB. All animals demonstrated obvious delayed contrast enhancement in the left ventricular wall following the Iohexol injection. The blood pool contrast agent revealed significant changes in cardiac function quantified by 3-D volume ejection fractions. All subjects demonstrated areas of myocardial infarct in the LAD distribution on both TTC staining and micro-CT imaging. The CNT micro-CT system aids straightforward, free-breathing, prospectively-gated 3-D murine cardiac imaging. Delayed contrast enhancement allows identification of infarcted myocardium after a myocardial ischemic event. We demonstrate the ability to consistently identify areas of myocardial infarct in mice and provide functional cardiac information using a delayed contrast enhancement technique.
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PMID:Delayed contrast enhancement imaging of a murine model for ischemia reperfusion with carbon nanotube micro-CT. 2563 38