Repeated intracoronary injections of contrast media. Additive hemodynamic and electrophysiologic effects in a dog model.

RATIONALE AND OBJECTIVES: Coronary arteriography in patients implies several selective injections into the coronary arteries. The authors investigate whether repeated injections cause additive cardiac hemodynamic and electrophysiologic effects in dogs. METHODS: Five repeated injections of 5 mL iohexol (Omnipaque 350 mgI/mL, Nycomed Imaging AS, Oslo, Norway), ioxaglate (Hexabrix 320 mgI/mL, Laboratory Guerbet, Cedex, France), and sodium meglumine-diatrizoate (Renografin-76 370 mgI/mL, Squibb Diagnostics, Princeton, NJ) were given into the left coronary artery in 7 anesthetized dogs and were compared with the effects after a 5 mL single injection of the same medium. Left ventricular (LV) pressures, LV dP/dtmax (inotropy) and epicardial monophasic action potential were recorded, from which monophasic action potential duration (MAPD) was measured. RESULTS: Repeated injections of ioxaglate and sodium meglumine-diatrizoate did not potentiate initial decrease in LV pressures and inotropy, but the secondary increase in LV inotropy increased more after repeated injections than after a single injection. Repeated injections of iohexol increased LV inotropy more than a single injection. All contrast media prolonged MAPD more after repeated injections than after single injections. MAPD was prolonged 30 sec after the last injection. CONCLUSION: Repeated injections of contrast media cause greater cardiac hemodynamic and electrophysiologic effects than a single injection during selective coronary arteriography.

Contrast media-induced ventricular fibrillation: an experimental study of the effects of dimeric contrast media during wedged catheter injection in dogs.

RATIONALE AND OBJECTIVES: We investigated the cardiac effects of an ionic dimer, ioxaglate and two nonionic dimers, iotrolan, and iodixanol. METHODS: During a simulated wedged catheter situation, 22 ml of each contrast medium was injected into the left anterior descending branch of the left coronary artery in seven open-chested, anesthetized dogs. RESULTS: Of 13 injections with each contrast medium, ioxaglate induced ventricular fibrillation in 11 after 34 +/- 5 sec, iotrolan in 6 after 42 +/- 4 sec, and iodixanol in 3 after 61 +/- 1 sec. Ioxaglate markedly lengthened monophasic action potential duration in contrast medium-perfused myocardium. Iotrolan, and iodixanol induced biphasic changes, first lengthening and then shortening action potential duration. The electrophysiological changes occurred later when using iodixanol. CONCLUSIONS: The risk of ventricular fibrillation during long-lasting contrast media exposure to the myocardium, as in a wedged catheter situation, appears to be much lower with iodixanol compared with ioxaglate and also lower than when using iotrolan.

Coronary arteriography with an oxygenated contrast medium: cardiac effects in dogs with and without acute ischemic heart failure.

RATIONALE AND OBJECTIVES: We investigated the possible cardiac effects of oxygen addition to contrast media (CM) during coronary arteriography in dogs that did and did not have ischemic heart failure. METHODS: Acute ischemic heart failure was induced by injecting small plastic microspheres into the left coronary artery of 18 dogs. Hemodynamic and electrophysiologic measurements were performed during a single injection before and during heart failure and during a single injection and five rapidly repeated CM injections during heart failure. Iohexol supplemented with electrolytes (iohexol + electrolytes = IPE), oxygenated IPE (IPE+O), Ringer acetate, and oxygenated Ringer acetate were injected into the left coronary artery. RESULTS: Single injections of IPE and IPE+O induced small hemodynamic and electrophysiologic effects. However, repeated injections of IPE and IPE+O increased left ventricular inotropy (maximum value of the first derivative of the left ventricular pressure) by 36% and 39%, reduced heart rate by 7% (for both), and lengthened QTc time (corrected QT interval) by 39 and 38 msec, respectively. A comparison of IPE and IPE+O revealed no statistically significant differences. CONCLUSION: Although electrolyte addition to nonionic CM may reduce the risk of cardiac complications during coronary arteriography, oxygenation does not seem to significantly further reduce this risk.

Additive hemodynamic and electrophysiologic effects of repeated intracoronary contrast media injections in dogs with heart failure.

RATIONALE AND OBJECTIVES: We investigated the cardiac effects of single and repeated contrast media injections in dogs with heart failure and compared the effects of iohexol with iohexol supplemented with electrolytes (30 mmol/l NaCl, 0.15 mmol/l CaCl2, 0.9 mmol/l KCl, and 0.1 mmol/l MgCl2; iohexol + electrolytes [IPE]). Although it has a higher osmolality than iohexol, IPE appears to be safer when injected through a wedged catheter. METHODS: Acute ischemic heart failure was induced by injections of small plastic microspheres into the left coronary artery of 16 anesthetized dogs. Iohexol, IPE, and Ringer acetate were injected into the left coronary artery either as a 5-ml single injection or repeatedly five times, once every 10th second. RESULTS: Single injections of iohexol and IPE induced small hemodynamic and electrophysiologic effects. However, repeated injections of iohexol and IPE increased the maximum rate of isovolumetric contraction by 46% and 36%, reduced heart rate by 8% and 7%, and lengthened QTc (the Q-T interval corrected for heart rate) time by 44 and 39 msec, respectively. No statistically significant differences were found in a comparison of IPE and iohexol. CONCLUSION: During heart failure, repeated injections of iohexol and IPE induced similar additive hemodynamic and electrophysiologic effects without inducing arrhythmias or serious hemodynamic changes.

Contrast-medium-induced ventricular fibrillation: arrhythmogenic mechanisms and the role of antiarrhythmic drugs in dogs.

RATIONALE AND OBJECTIVES: Small electrolyte additions to a nonionic contrast medium reduce the risk of ventricular fibrillation (VF) during wedged catheter injection of a contrast medium. The current study was designed to further investigate contrast-medium-induced VF by studying the effect of pretreatment with different antiarrhythmic drugs. METHODS: During a simulated wedged catheter situation, iohexol was injected into the anterior descending branch of the left coronary artery in five open-chest, anesthetized dogs pretreated with lidocaine, propranolol, amiodarone, almokalant, or verapamil. RESULTS: Wedging the catheter for 60 sec did not induce VF. However, all 15 wedged catheter injections with iohexol induced VF within 28 sec (19 +/- 1 [mean +/- standard error of the mean]) despite pretreatment with antiarrhythmic drugs. Prior to VF, conduction was slowed and monophasic action potential duration lengthened in the contrast-medium-perfused myocardium, although no significant changes occurred in the control area. CONCLUSION: The combination of catheter wedging and long-lasting contrast medium injection has a high risk of causing VF. Although adding a small amount of electrolytes to nonionic contrast media can reduce the risk of VF, antiarrhythmic drug therapy may not have a protective effect.

Changes in radiological routines following the introduction of computed tomography. A retrospective study from two Norwegian hospitals.

Diagnostic imaging routines have changed rapidly during the last two decades. The real revolution started with the introduction of computed tomography into routine clinical work in the middle of the 1970s. Simultaneously, a tremendous sophistication of ultrasonography took place, and shortly later, magnetic resonance imaging started its "career." The present report explores how the introduction of computed tomography changed imaging routines in two major Norwegian hospitals during the last 10 to 15 years.

Ultrasonography in medical imaging. Influence on diagnostic routines.

It has been assumed that the introduction of ultrasonography in diagnostic imaging has led to dramatic changes in imaging routines by replacing other modalities like angiography, intravenous urography, and computerized tomography in several diagnostic procedures. The present retrospective study from five Norwegian hospitals during the period from 1978 to 1991 confirm this assumption, showing how ultrasonographic examinations have influenced diagnostic routines.

Imaging routines for the esophagus, small bowel, abdomen, and liver in six Norwegian hospitals from 1975 to 1993.

The roles of liver scintigraphy in addition to other imaging modalities of the esophagus and the small bowel and the use of abdominal flat films were studied in six Norwegian hospitals between 1975 and 1993. Parallel to the introduction of ultrasonography, the use of liver scintigraphy disappeared almost completely. Barium studies of the esophagus, to some degree, have been replaced by endoscopy, whereas use of barium studies of the small bowel remained unchanged or increased. The number of flat-film studies of the abdomen performed remained unchanged.

Changes in diagnostic imaging routines of the stomach and the large bowel during the period between 1975 and 1992.

In a retrospective study on diagnostic imaging of the stomach and large bowel, we evaluated the examination routines in six Norwegian hospitals for the period between 1975 and 1992. For both organ systems, a shift in routines from radiological examination toward endoscopy was observed. For the stomach there was a significant correlation between an increase in the use of endoscopy and a decrease in the use of X-ray examinations. Additionally, the total number of stomach examinations had declined. For the large bowel, the total number of endoscopic and radiological examinations had increased for all hospitals studied. While not as prominent as for the stomach, an obvious shift from X-ray examinations toward endoscopy was observed. These results should be considered when planning new imaging departments and hospitals in Norway.

[Spread of an imported multiresistant Staphylococcus aureus to other hospitals via secondary colonized patients]. / Spredning af en importeret multiresistent Staphylococcus aureus til andre sygehuse via sekundaert koloniserede patienter.

UNLABELLED: A secondary spread of an imported methicillin-resistant Staphylococcus aureus strain (MRSA) to two other patients occurred within a Danish surgical ward in spite of isolation of a multitraumatized index-patient immediately after arrival from a hospital in the Mediterranean area. The two other colonized patients were later transferred to other hospitals in Denmark where it became apparent that they had developed serious infections with the MRSA strain. IN CONCLUSION: to prevent spread of imported MRSA within Danish hospitals, strict adherence to isolation procedures and a high level of general hygiene is essential not only when patients are transferred from hospitals situated in endemic areas of MRSA abroad, but also when admitted from Danish hospital wards where known cases of colonisation or infection with MRSA exist.

Electrolyte addition to nonionic contrast media. Cardiac effects during experimental coronary arteriography.

Although the incidence of serious adverse effects is low during clinical coronary arteriography, life-threatening cardiovascular complications occasionally occur. Ventricular fibrillation (VF) is most often seen during contrast media (CM) injection through a wedged catheter. A simulated wedged catheter model in dogs has therefore been developed. Further, patients with heart failure are at greater risk for CM-related side effects during coronary arteriography. Thus, an acute ischemic heart failure model has been used. The present thesis was designed to investigate the cardiac electrophysiologic and hemodynamic effects of CM during selective coronary arteriography in normal and failing hearts, and in particular the role of electrolyte addition to nonionic CM. The risk of spontaneously induced VF and the arrhythmogenic mechanisms were studied when using iso-osmolal and low-osmolal CM having different contents of electrolytes, and after pretreatment with antiarrhythmic drugs. Further, effects of adding electrolytes to nonionic CM during single and fast repeated injections in normal and failing hearts were studied. Also possible effects of oxygenating CM were studied. CM injection in a wedged catheter situation had a high risk for VF. Probably, VF was due to induced regional electrophysiologic changes in ventricular activation and repolarization. Pretreatment with antiarrhythmic drugs did not prevent VF. However, addition of low concentrations of electrolytes to nonionic CM reduced the risk for VF in a wedged catheter situation. The results indicate that side-effects of CM during coronary arteriography are related mainly to the passive washout of cardiac electrolytes. Electrolyte shifts during coronary arteriography may change the myocardial Na/Ca balance and cellular calcium control. The nonionic, iso-osmolal CM iodixanol, with a balanced content of sodium and calcium and the low-osmolal, nonionic CM iohexol, also with a balanced content of electrolytes, had about the same low risk for inducing VF and presented a much lower risk for inducing VF than did iohexol and ioxaglate in a wedged catheter situation. Single injection of iohexol with a balanced eletrolyte addition induced only minimal electro-physiologic changes and was well tolerated hemodynamically. Repeated intracoronary CM injections during ischemic heart failure were associated with similar additive electrophysiologic and hemodynamic changes as when using iohexol without electrolyte supplement. Oxygenated and nonoxygenated CM presented the same risk for inducing VF. Only minor electrophysiologic and hemodynamic differences could be detected during wedged catheter injection. In conclusion, addition of key electrolytes to nonionic CM can reduce the risk of cardiac complications during coronary arteriography. Oxygenation of CM does not seem to significantly further reduce the risk.

Hemispheric differences for visual matrix processing: stimulus size and spatial frequency effects.

Hemispheric processing differences were assessed by presenting square matrices that varied in size and the number of filled-in cells. Subjects judged whether the matrix contained an even or odd number of filled cells. Experiment 1 employed relatively small matrix sizes (2 x 2, 3 x 3, and 4 x 4), and Experiment 2 employed relatively large matrix sizes (4 x 4, 6 x 6, and 8 x 8). Response time was shorter and error rates lower for left visual field/right hemisphere (LVF/RH) presentations compared to right visual field/left hemisphere (RVF/LH) presentations, with the larger matrices demonstrating the strongest visual field/hemispheric effects. Increases in the number of filled cells contributed to increases for the LVF/RH response time advantage only for the larger arrays. Analysis of the data from both studies collapsed across the number of filled cells produced highly consistent LVF/RH advantages for both response time and error rate, with stronger LVF/RH advantages found for the larger matrix sizes of both studies. The findings suggest that visual stimulus spatial frequency is a key determinant of hemispheric processing advantages, but that this factor is constrained by stimulus size variation. Theoretical implications with respect to the hemispheric processing double filtering by frequency model are discussed.

[Restenosis after coronary angioplasty]. / Restenose etter koronar angioplastikk.

Angiography of 169 patients who had been treated successfully with PTCA showed restenosis in 61. Of these, 38 were successfully treated with a new PTCA, and six developed a new restenosis. Restenosis usually appears during the first four months after PTCA in vessels with a diameter less than three millimeters. The authors emphasize the importance of careful clinical follow-up.

Renal angiography may be used primarily in the diagnosis of renovascular hypertension.

Three hundred and twenty consecutive patients with hypertension were referred to examination with intravenous urography. Only 2 of the 320 urograms performed showed abnormalities possibly related to hypertension. Renal angiography was performed in 39 (12%) of the patients. Seventeen (7%) subjects had renal artery stenosis, of whom 8 (2.5%) were referred to surgery. Four became normotensive and the other 4 had a more treatable hypertension. Urography is an expensive and insensitive method for evaluation of patients with hypertension and should be abandoned. Proper treatment of renovascular hypertension demands the performance of renal angiography. We therefore suggest a program for primary use of renal angiography in the examination of patients with suspected renovascular hypertension.

Restenosis after percutaneous transluminal coronary angioplasty.

Restenosis after percutaneous transluminal coronary angioplasty was demonstrated in 61 (29%) of 210 successfully treated patients. Mostly it occurred within 4 months after treatment and in arteries less than 3 mm in diameter. Careful clinical follow-up is therefore particularly important early after angioplasty of smaller arteries. Redilation can be performed without increased risk of restenosis.

Intravenous urography and voiding cystoureterography in northern Norway: a retrospective study.

Intravenous urography (IU) was performed in 489 patients aged 0-9 years during 1980-1983. A total of 35 (7.2%), 19 (13.1%) boys and 16 (4.7%) girls had pathological changes at IU. Of these, 11 boys and 5 girls had findings with therapeutic consequences. We have analysed the results of IU and voiding cystoureterography (VC) in 62 patients and show that a normal IU does not exclude vesicoureteral reflux into the renal pelvis. By performing only VC hydronephrosis, pyelonephritic scarring and anomalies may be missed.

Cardiac effects of coronary arteriography with electrolyte addition to iohexol. A study in dogs with and without heart failure.

Electrolyte addition to nonionic contrast media has been suggested to further reduce the incidence of ventricular fibrillation during coronary arteriography. The present study was designed to investigate the effects of adding 30 mM NaCl, 0.9 mM KCl, 0.15 mM CaCl2 and 0.1 mM MgCl2 to iohexol on cardiac electrophysiology and hemodynamics (iohexol+electrolytes = IPE). Contrast media were injected into the left main coronary artery in 9 open-chest, anesthetized dogs before and after induction of acute ischemic heart failure. IPE increased left ventricular inotropy (LV dP/dtmax) with no initial decrease, even during heart failure. During heart failure IPE induced the same hemodynamic effects as iohexol without electrolyte addition. IPE slightly lengthened epicardial monophasic action potential duration before heart failure. We conclude that IPE appears to be well tolerated hemodynamically. The electrophysiologic differences between IPE and iohexol are small when the injection time is not longer than 5 s.

Cardiac effects of adding electrolytes and oxygen to iohexol in a dog model of contrast media-induced ventricular fibrillation.

We investigated whether addition of a balanced electrolyte supplement and oxygen to the nonionic contrast medium iohexol reduces the risk of ventricular fibrillation (VF), and studied regional electrophysiology prior to the VF event. Twenty ml of each test solution were infused at a rate of 0.5 ml/s into the left anterior descending coronary artery (LAD) in 8 anesthetized dogs. LAD was externally occluded during infusion, to simulate a wedged catheter situation. ECG, hemodynamics, regional epicardial monophasic action potential duration (MAPD) and ventricular activation times (VAT) were calculated. All infusions with iohexol caused VF within 27 s. Five of 12 infusions with iohexol + 30 mmol NaCl, 3 of 11 infusions with iohexol+electrolytes (IPE) NaCl, KCl, CaCl2 and MgCl2) and 4 of 11 infusions with IPE with oxygen addition (IPE+O2) caused VF after 45 s. Iohexol did not change MAPD prior to the VF event. Iohexol + 30 mmol NaCl and the IPE solutions lengthened MAPD initially, but at the time of the VF event MAPD were normalized or shortened. We conclude that electrolyte supplement to iohexol may prevent VF, probably by lengthening MAPD.

[Diagnostic imaging of the gastrointestinal and biliary tracts. Pattern of examinations during the period 1975-90]. / Bildediagnostikk av gastrointestinalkanalen og galleveiene. Undersøkelsesmønsteret 1975-90.

The procedures used for imaging of the gastrointestinal tract, the gall bladder and the bile ducts were registered in six Norwegian hospitals during the period 1975-90. Data obtained from all hospitals showed a significant decrease in radiological examinations of the stomach and the large bowel, and a dramatic decrease of such examinations in the case of the gall bladder and bile ducts. The changes are mainly due to the increasing use of newer methods such as ultrasonography, gastroscopy and colonoscopy. The shift in the pattern of examinations, as shown in the present study, may well have many implications for patients and for the health service as a whole.