Mechanisms of blood pressure change after bolus injections of X-ray contrast media

Hemodynamic effects of intravenous bolus injection of iopromide 370 twice in abdominal contrast-enhanced CT and coronary CTA dual-site sequential examinations

Little information is available about how intravenous bolus injection of iopromide 370 twice in a short time will affect hemodynamics and whether the changes reach clinically relevant levels. In the present study, 31 healthy adult volunteers received abdominal contrast-enhanced CT and coronary CTA sequential examinations. The same dose and rate of normal saline was injected 30 min in advance as self-control. Hemodynamic data were noninvasively collected at selected time points from 1 min prior to injection to 30 min post-injection. The results showed that after iopromide 370 injection, except for stroke volume, all other indicators changed immediately during the first injection, changed most significantly during the second injection (P < 0.05), and returned to baseline within 10 min. Heart rate and cardiac output exhibited the most pronounced changes, with an increasing rate of 33.5% and 33.8%, respectively. For indicators with a change range of > 15% during the second injection, except for mean arterial pressure and total peripheral resistance, the proportions of subjects for the other indicators between the two groups were statistically different (P < 0.05). In conclusion, intravenous bolus injection of iopromide 370 twice in dual-site sequential examinations induced dose-cumulative and time-dependent hemodynamic effects, which all fluctuated within the normal ranges.

Augmentation of Electrocardiographic QRS R-Amplitude Precedes Radiocontrast-Induced Hypotension during Mobile Computed Tomography Scanning

Although intravenous administration of contrast media may trigger a variety of adverse reactions, sedated patients undergoing computed tomography (CT) scanning usually are not able to report their symptoms, which may delay detection of adverse reactions. Furthermore, changes in vital signs cannot be typically measured during mobile CT scanning, which worsens the situation. We aimed to characterize contrast-related hemodynamic changes that occur during mobile CT scanning and predict sudden hypotension based on subtle but robust changes in the electrocardiogram (ECG). We analyzed the digitized hemodynamic data of 20 consecutive patients who underwent clipping of a cerebral artery aneurysm and contrast-enhanced CT scanning following the surgical procedure. Hemodynamic variables, including ECG findings, invasive blood pressure (BP), pulse oximetry results, capnography findings, cardiac output, and systemic vascular resistance, were monitored simultaneously. We measured morphological changes in ECG-derived parameters, including the R-R interval, ST height, and QRS R-amplitude, on a beat-to-beat basis, and evaluated the correlation between those parameters and hemodynamic changes. After the radiocontrast injection, systolic BP decreased by a median 53 mmHg from baseline and spontaneously recovered after 63 ± 19 s. An increase in QRS R-amplitude (median 0.43 mV) occurred 25 ± 10 s before hypotension developed. The receiver operating characteristic curve showed that a 16% increase in QRS R-amplitude can predict a decrease in systolic BP of >25% (area under the curve 0.852). Increased cardiac output (median delta 2.7 L/min from baseline) and decreased systemic vascular resistance (median delta 857 dyn·s/cm⁵ from baseline) were also observed during hypotension. During mobile CT scanning, profound but transient hypotension can be observed, associated with decreased vascular resistance. Augmentation of QRS R-amplitude from an ECG represents a sensitive surrogate for onset of a hypotensive episode after contrast injection, thereby serving as a simple and continuous noninvasive hemodynamic monitoring tool.

X-ray contrast media mechanisms in the release of mast cell contents: understanding these leads to a treatment for allergies

A long history of searching for the etiology of X-ray contrast material (CM) reactions has led to the understanding that the CM do not produce anti-CM antigens. Since CM reactions are anaphylactoid in nature, however, a source for mast cell activation was sought. This resulted in the finding that concentrated CM could suppress mast cell activation by attachment to the Fc portion of IgE and IgG. This is presumed to be a steric hindrance effect. In a study of the effects of CM on BP and a study of the effects of CM in sensitized rats, it was concluded that less concentrated CM activated mast cells and that this mechanism was best explained by bridging of adjacent IgE molecules via attachment to their Fc segments. The mast cell release of heparin activating the contact system, as well as the release of histamine, is believed to be responsible for CM reactions and allergic diatheses.

Rebleeding of ruptured cerebral aneurysms during three-dimensional computed tomographic angiography: report of two cases and literature review

Although three-dimensional computed tomographic angiography (3D-CTA) is less complicated and time-consuming than conventional cerebral angiography (CCA) and represents a reliable alternative for evaluating cerebral aneurysms, some patients experience aneurysmal rerupture during 3D-CTA. Two women, 79 and 71 years old, who presented with severe subarachnoid hemorrhage (SAH) underwent 3D-CTA within 3 h after SAH onset. Their images clearly indicated extravasation from their aneurysms. Neither patient recovered from deep coma, and both died within 2 days. We reviewed the literature with special reference to the condition of SAH patients at admission and the interval between SAH onset and 3D-CTA, and discuss serious complications of 3D-CTA study. Although aneurysmal rerupture may reflect the natural course, rerupture during 3D-CTA, especially in SAH patients who are in poor clinical condition during the acute stage, should be recognized as a potentially fatal complication. Their blood pressure must be strictly controlled and factors such as their clinical condition and the interval from the ictus must be considered.