Neurological outcomes following intraprocedural rerupture during coil embolization of ruptured intracranial aneurysms

OBJECT

Intraprocedural rerupture (IPR) of intracranial aneurysms during coil embolization is associated with significant periprocedural disability and death. However, whether this morbidity and mortality are secondary to an increased risk of vasospasm and hydrocephalus is unknown. The authors undertook this study to determine the in-hospital and long-term neurological outcomes for patients with aneurysmal subarachnoid hemorrhage (SAH) treated with coil embolization who suffer aneurysm rerupture during treatment.

METHODS

The records of 156 patients admitted with SAH from previously untreated, ruptured, intracranial aneurysms and treated with endovascular coiling between January 2007 and January 2014 were retrospectively reviewed. Twelve patients (7.7%) experienced IPR during coil embolization.

RESULTS

Compared with the cohort of patients with uncomplicated coil embolization procedures, patients with aneurysm rerupture were more likely to require external ventricular drain (EVD) placement (91.7% vs 58.3%, p = 0.02) and postprocedural EVD placement (36.4% vs 7.1%, p = 0.01), to undergo permanent ventriculoperitoneal shunt placement (50.0% vs 18.8%, p = 0.02), to develop symptomatic vasospasm (50.0% vs 18.1%, p = 0.02), and to have longer lengths of hospital stay (median 21.5 days vs 15.0 days, p = 0.04). Admission Hunt and Hess, modified Fisher, and Barrow Neurological Institute grades did not differ between the 2 cohorts, nor did long-term functional neurological outcomes as assessed by the modified Rankin Scale.

CONCLUSIONS

Intraprocedural rerupture during coil embolization for ruptured intracranial aneurysms is associated with an increased risk of symptomatic vasospasm and need for temporary and permanent cerebrospinal fluid diversion for hydrocephalus.

The contrast media iohexol causes vasoconstriction of the proximal left anterior descending coronary artery: implications for appropriate stent sizing

The effect of the contrast agent iohexol on reference vessel size in patients with proximal left anterior descending disease is unknown. Quantitative coronary angiography and intravascular ultrasound were performed in 15 patients with atherosclerotic disease of the proximal left anterior descending. Mean proximal reference vessel diameter was 2.95 +/- 0.59 mm with quantitative coronary angiography and 4.65 +/- 0.66 mm with intravascular ultrasound (P < .05). Intracoronary injection of iohexol resulted in a significant decrease in intravascular ultrasound-measured proximal reference vessel diameter from 4.65 +/- 0.66 mm to 4.47 +/- 0.68 mm (P = .002). Vasoconstrictive response to iohexol in the proximal reference vessel ranged from -0.04 mm to 0.5 mm with a mean of 0.18 +/- 0.16 mm. This study shows that iohexol can cause significant vasoconstriction of the proximal reference vessel in patients with severe disease involving the proximal left anterior descending.

Effects of iodinated contrast media on common carotid and brachial artery blood flow and wall shear stress

The aim of our study was to evaluate the effect of the intravenous contrast media iomeprol on wall shear stress, blood flow and vascular parameters in the common carotid and brachial artery. Thirty outpatients undergoing thoracic or abdominal spiral CT scans were studied. The internal diameter and flow velocity of the common carotid and brachial artery were evaluated by ultrasound, and blood viscosity was measured before and after low osmolality iomeprol (Iomeron 350) injection. The wall shear stress, blood flow and pulsatility index were calculated. To test the differences between groups, the Wilcoxon rank test and Mann Whitney U test were applied. Blood viscosity decreased slightly, but significantly after contrast media (4.6+/-0.7 vs. 4.5+/-0.7 mPa.s, P = 0.02). Contrarily, blood flow and wall shear stress did not change in the common carotid artery, but significantly decreased in the brachial artery (0.9+/-0.4 vs. 0.6+/-0.3 ml/s, P < 0.0001, and 41.5+/-13.9 vs. 35.3+/-11.0 dynes/cm2, P < 0.002, respectively), whereas the pulsatility index significantly increased in the brachial artery (5.0+/-3.3 vs. 7.5+/-5.3, P < 0.001). Iomeprol injection causes blood flow and wall shear stress reduction of the brachial artery; the rise in the pulsatility index suggests an increase in peripheral vascular resistance. Further investigation is needed to evaluate whether these modifications can be clinically relevant.

Nonionic contrast media iohexol and iomeprol decrease renal arterial tone: comparative studies on human and porcine isolated vascular segments

RATIONALE AND OBJECTIVES

The vasoconstriction of the renal arteries is frequently considered as a crucial factor for radiocontrast-induced nephropathy. A direct effect of iodinated radiographic contrast medium (RCM) on vascular smooth muscle is supposed to be one component of the vascular response. We studied the effect of the nonionic RCM iomeprol and iohexol on the tonus of isolated human and porcine renal arteries in vitro.

METHODS

In an organ bath renal arterial rings, uncontracted or precontracted by 10 micromol/L phenylephrine were incubated with increasing concentrations (15-103 mg iodine/mL) of iohexol, iomeprol, and mannitol solution isoosmolar to the contrast media. In a part of the preparations the endothelium was destroyed. Human vessels were obtained from tumor nephrectomy specimens of 10 patients.

RESULTS

In human experiments iomeprol and iohexol (P < 0.05) relaxed renal arterial rings whereas mannitol produced concentration-dependent contractions. The relaxation by both contrast media was slightly attenuated upon increasing their concentration. The differences between mannitol solutions and RCM were statistically significant (P < 0.001) at concentrations of 57 mg iodine/mL and higher. Precontracted rings were significantly stronger relaxed by the RCM compared with mannitol (P < 0.001). The contrast medium induced relaxation did not depend on the presence of an intact endothelium (P > 0.05). Experiments with renal arterial segments prepared from swine showed similar results, with stronger relaxations than the human preparations.

CONCLUSION

Iomeprol and iohexol relaxed isolated renal arterial segments. These observations are in contradiction with the hypothesis that contrast media induce nephropathy by a direct vasoconstrictive effect on vascular smooth muscle. They do not exclude, however, a reduction of renal blood flow by other factors like liberation of hormones.

Iodinated radiographic contrast media inhibit the capacitative calcium entry into smooth muscle cells of the swine renal artery

RATIONALE AND OBJECTIVES

To investigate whether nonionic, iodinated, radiographic contrast media (RCM) could modulate calcium release from or calcium entry into smooth muscle cells of the swine renal artery.

METHODS

Intracellular calcium concentrations of isolated myocytes loaded with the calcium-sensitive dye fluo-3 were analyzed using a fluorescence imaging system. Calcium signals were compared with isometric contractions of vascular segments in an organ bath. The effects of the triiodinated monomer iomeprol were compared with those of a mannitol solution.

RESULTS

Stimulation of alpha-receptors by phenylephrine caused a biphasic calcium signal. Transient liberation of calcium from intracellular stores triggered the sustained entry of extracellular calcium (capacitative entry). Iomeprol and mannitol slightly inhibited the initial transient spike to the same extent. The calcium influx was reversibly inhibited by RCM by about 50%. Up to a concentration of 40 mmol/L, the inhibition induced by iomeprol was significantly higher than that induced by mannitol (P < 0.05-0.01). In isolated arterial segments, relaxation of the contraction phase depending on the calcium influx was significantly higher with the RCM than with mannitol (P < 0.01).

CONCLUSIONS

Vasodilatation by CM is associated with a reduction in the capacitative entry of calcium. The mechanism of this effect is not clear, but it can be ruled out that it is mainly due to the high osmolarity of these compounds.

Effect of dopamine on excretory urographic image quality and the prevention of contrast-induced nephropathy in dogs

The effect of low dose dopamine on the excretory urographic image quality and contrast media-induced nephropathy in normal dogs (experiment 1) and the dogs with decreased renal function (experiment 2) were assessed. In experiment 2, decreased renal function was induced by gentamicin overdose. In each experiment, animals were divided into 3 groups. In group 1, only contrast medium (iohexol) was administered. In group 2, contrast medium plus intravenous fluid (0.9% saline) were administered. And in group 3, contrast medium plus intravenous fluid and low dose dopamine were administered. Investigated parameters included intrarenal resistive index (RI), serum BUN and creatinine concentrations, contrast medium elimination time and radiographic image quality. In experiment 1, RI of group I increased at 80 min after contrast medium administration (p<0.05), but RI of group 3 decreased at 48 and 72 hr (p<0.05). Serum BUN concentration of group 1 was higher than that of group 2 and 3 (p<0.05); in radiographic examination, contrast medium elimination time decreased in group 2 and 3, but image quality of group 2 was inferior to that of group 3. In experiment 2, image quality of group 3 only provided adequate visualization of renal structures. The formula of contrast medium plus low dose dopamine was found to provide good nephrogram and pyelogram image quality without supplemental contrast medium, and to protect renal tubules from prolonged exposure to concentrated contrast medium.

Systemic and regional haemodynamic effects of aortofemoral angiography

The aim was to investigate the regional and systemic haemodynamic consequences of bolus injection of fluids with different physical properties in the course of routine aortography. Iopamidol was compared with an equiosmolar solution of mannitol and with a 0.9 N saline solution. Continuous blood flow and Pulsatility Index (PI), as an index of regional vascular resistance, were measured by Doppler technique. Finger arterial pressure and heart rate were monitored at the time and for 3 min following each intraaortic bolus injections. The patients who underwent routine aortography were grouped according to the site of the flow measurements: common femoral artery, common carotid artery and brachial artery. Flow changes induced by the bolus infusion were evident for all the fluids but only at the femoral artery level. After an immediate (3 +/- 2 s) and brief (2 +/- 2 s) but marked reduction of flow and in-phase increase of PI following the bolus, further haemodynamic changes were observed only in the femoral artery, with a peak at 35 +/- 10 s and returning to baseline values after 70 +/- 15 s, in terms of both increased mean blood velocity and decreased PI. Saline and mannitol induced overall blood velocity alterations of 54% and 80%, respectively, and PI reductions of 44% and 57% compared with those induced by iopamidol. In the other vascular areas there was only a 17 +/- 2% increase of the physiological early diastolic backflow at the brachial artery level. Blood pressure decreased and heart rate increased in phase with the flow changes of the femoral artery.

IN CONCLUSION

(1) a dramatic rheodynamic perturbation at the site of injection induces a vasodilating stimulus; (2) the haemodynamic response following injection results in marked vasodilation of only the tributary vascular bed; (3) flow steal may occur from other beds towards the lower limb vascular beds owing to vascular impedance imbalance; (4) a reduction of systemic arterial pressure is induced in phase with the regional vascular events and a reflex increase of the heart rate; and (5) the physical properties of the injected fluids influence the intensity of the perturbation, although the decisive triggering factor is the counterflowing bolus per se.

The impact of coronary artery disease on the coronary vasomotor response to nonionic contrast media

BACKGROUND

Coronary artery disease (CAD) alters the vasomotor response to a variety of pharmacological agents. We tested the hypothesis that CAD also has an impact on the coronary vasomotor response to radiologic contrast media.

METHODS AND RESULTS

We performed quantitative coronary angiography in 42 patients without angiographic evidence of CAD and 38 patients with CAD in the left coronary artery. Angiographically smooth coronary segments (n=235) were analyzed for changes on luminal diameters and coronary venous oxygen saturation in response to 3 media: the nonionic dimer iodixanol, the nonionic monomer iopromide, and the ionic agent ioxaglate. In subjects without CAD, we assessed the effects of intracoronary administration of the nitric oxide synthase inhibitor N(G)-monomethyl-L-arginine and of the cyclooxygenase inhibitor indomethacin on such changes. Iodixanol induced coronary vasodilation in subjects without CAD (8.8+/-8.6%, P<0.001). Patients with CAD exhibited no significant diameter changes in segments >/=20 mm apart from a stenosis (4.7+/-9.4%, P=NS) and significant constriction in segments <20 mm from a stenosis (-3.8+/-4.6%, P<0. 05). Similar results were obtained with iopromide, but no changes were found with ioxaglate. All contrast media induced transient (<35 seconds) increases in coronary venous oxygen saturation in all subjects. Indomethacin, but not N(G)-monomethyl-L-arginine, blunted the vasodilating effect of iodixanol and iopromide (by 80% and 76%, respectively; P<0.001).

CONCLUSIONS

Nonionic contrast media induce a vasodilatory response in normal vessels not by a mechanism involving increased flow or endothelial nitric oxide synthesis, but rather by depending on preserved vascular cyclooxygenase activity. CAD changes normal epicardial vasodilatory response into vasoconstriction.

Local effect of three nonionic contrast media on the arterial blood flow velocity during iliofemoral arteriography

RATIONALE AND OBJECTIVES

To investigate the influence of nonionic contrast media on the arterial blood flow velocity (BFV) during iliofemoral arteriography.

MATERIALS AND METHODS

Iliofemoral arteriography with three contrast media--iopromide, iopamidol, and iodixanol--was carried out in 55 patients in a prospective manner. Hemodynamic changes were investigated using the change in the maximal systolic BFV in the dorsal artery of the foot and were recorded by simultaneous Doppler sonography.

RESULTS

Comparable reductions in BFV were demonstrated for iopromide and iopamidol, but the iso-osmolar iodixanol produced no change in the maximal systolic BFV. The reduction in BFV by iopromide and iopamidol is attributed to a vasoconstrictive effect on the resistance vessels and is explained by a direct depolarization of the vascular smooth muscles with predamaged endothelium; the effect lasts for less than 1 minute. The time from the greatest change in BFV until the baseline value was achieved (recovery time) depended on the degree of vascular damage present. This can be explained by the inadequate compensation in circulatory regulation of patients with peripheral arterial occlusive disease. Iodixanol's lack of influence on BFV may result because its osmolality and chemotoxicity differ from those of iopromide and iopamidol.

CONCLUSIONS

The peripheral hypoxemia observed in patients with arteriosclerotic vascular changes can be expected to increase through the vasoconstrictive effect of iopromide and iopamidol, whereas no such blood flow deficit is to be expected with the use of iodixanol. Nevertheless, the reduction in blood flow is of short duration and thus will probably not contribute significantly to this hypoxemia.

The differential effect of contrast agents on endothelial cell and smooth muscle cell growth in vitro

PURPOSE

This study was designed to evaluate the effects of ionic and nonionic contrast agents on endothelial cell (EC) and smooth muscle cell (SMC) proliferation, and to determine the role of osmolality as the etiology of these effects.

METHODS

Cultured bovine aorta EC and SMC were exposed to ionic (iothalamate meglumine) or nonionic (ioversol or iopamidol) contrast, or varying osmolar solutions of mannitol, for periods of 1, 3, 5, 10, or 20 minutes. Cells were then incubated in growth media at 37 degrees C and proliferation and structure were assessed 1, 3, 5, and 7 days later.

RESULTS

Both EC and SMC showed decreased proliferation after brief exposure to both ionic and nonionic contrast. Proliferation was markedly decreased at 24 hours after exposure, and began to recover by day 3 after exposure. EC showed a significant decrease up to 7 days after exposure to ionic contrast (p < 0.03), whereas SMC showed a significant decrease up to 7 days after exposure to nonionic contrast (p < 0.001). The decrease in proliferation was directly dependent on the length of exposure to the contrast and the concentration of the contrast. EC proliferation decreased in proportion to increasing osmolality of the test solution (p < 0.05). SMC proliferation did not show a decrease proportional to osmolality. No change was observed in cell viability as assessed by LDH activity studies. After contrast exposure, bare areas with no cells present were noted in the previously confluent EC and SMC culture wells. Cell structure was altered immediately after exposure to contrast, with normal structure recovered by 24 hours after exposure.

CONCLUSION

This study demonstrates that brief exposure to contrast agents injures EC and SMC, altering their structure and decreasing proliferation for up to 7 days in vitro. This response is both dose and time dependent. EC are more severely affected by ionic contrast, and SMC are more severely affected by nonionic contrast. EC injury appears to be mediated by the osmolar effect of the contrast, but the effects of contrast on SMC seem to be due to a different mechanism.