Effects of radiographic contrast media on pulmonary vascular resistance of normoxic and chronically hypoxic pulmonary hypertensive rats

Effects of iodinated contrast media on blood and endothelium

The aim of the study was to assess the effects of iodinated contrast media on blood components and endothelium based on experimental and clinical studies and to produce clinically relevant guidelines for reducing thrombotic and hematologic complications following the intravascular use of contrast media. A report was drafted after review of the literature and discussions among the members of the Contrast Media Safety Committee of the European Society of Urogenital Radiology. The final report was produced following discussion at the 12th European Symposium on Urogenital Radiology in Ljubljana, Slovenia (2005). Experimental data indicate that all iodinated contrast media produce an anticoagulant effect and that this effect is greater with ionic contrast media. Several of the in vitro and experimental in vivo studies on haematological effects of contrast media have not been confirmed by clinical studies. Low- or iso-osmolar contrast media should be used for diagnostic and interventional angiographic procedures, including phlebography. Meticulous angiographic technique is the most important factor for reducing the thrombotic complications associated with angiographic procedures. Drugs and interventional devices that decrease the risk of thromboembolic complications during interventional procedures minimize the importance of the effects of contrast media.

Effects of iohexol on ventilatory functions in patients undergoing diagnostic coronary angiography

BACKGROUND AND OBJECTIVES

Adverse respiratory reactions have been reported with intravascular radiographic contrast media. The aim of the present study is to assess the effects of iohexol on pulmonary functions in patients undergoing diagnostic coronary angiography (CA).

MATERIALS AND METHODS

30 patients enrolled in the study. The respiratory functions of the patients were measured at three different stages during angiography (before, immediately after and 2 h later) and arterial blood gas analyses were performed at six stages during CA (before, immediately after the insertion of angiography catheter, 2 min after the injection of contrast agent, at the end of angiography, an hour and 2 h after angiography). A single, experienced angiographer performed the angiography procedures via radial artery route. Totally six multiple angled views of the left and right coronary arteries were recorded in all patients by hand injection. None of the patients were performed ventriculography.

RESULTS

Angiography caused significant reduction in forced expiratory volume in 1 sec [FEV1] (from 103 +/- 15 to 95 +/- 17, p < 0.01), forced vital capacity [FVC] (from 99 +/- 13 to 95 +/- 18, p < 0.05) and maximum mid-expiratory flow rate [MMF] (from 95 +/- 33 to 84 +/- 29, p < 0.01) whereas there were no significant changes in the mean FEV1/FVC ratios at different stages of angiography. Statistically significant decrease in PaO2 (from 91 +/- 10 to 85 +/- 13 mmHg, p < 0.01) and arterial O2 saturation (from 97 +/- 1% to 96 +/- 1%, p < 0.01) were also observed. Data in present study showed a clinically insignificant but statistically significant restrictive impairment in pulmonary functions.

CONCLUSIONS

Diagnostic CA using iohexol decreases ventilatory functions in a small but significant extent in patients without any overt pulmonary disease.

Safety and Hemodynamic Effects of Pulmonary Angiography in Patients with Pulmonary Hypertension: 10-Year Single-Center Experience

OBJECTIVE

We sought to examine the incidence of complications and change in pulmonary artery pressure in patients with pulmonary hypertension who were undergoing pulmonary angiography.

MATERIALS AND METHODS

A retrospective review was performed for all patients who underwent pulmonary angiography over a 10-year period at a single institution. Patients with moderate pulmonary hypertension (pulmonary artery pressure, 30-59 mm Hg) and severe pulmonary hypertension (pulmonary artery pressure, >/= 60 mm Hg) served as the study population. Demographic data, clinical indication, pre- and postcontrast pulmonary artery pressure measurements, type of pulmonary hypertension, contrast agent volume, complications, and American Society of Anesthesiologists (ASA) classification were recorded for all patients and compared.

RESULTS

Two hundred two of 612 patients who underwent pulmonary angiography had pulmonary hypertension. Moderate pulmonary hypertension was present in 155 patients (77%) and severe pulmonary hypertension, in 47 patients (23%). Three (2.0%) of four complications were fatal. The complication rate was higher in patients with severe pulmonary hypertension compared with patients with moderate pulmonary hypertension but not statistically significant (6.3% vs 0.6%, p = 0.63). Patients with complications had a higher mean ASA score than those without complications (4.0 vs 3.0, p = 0.03). Patients with lung transplants had the greatest increase in pulmonary artery pressure after pulmonary angiography compared with all other clinical indications (16.75 +/- 12.97 mm Hg vs 5.46 +/- 6.86 mm Hg, p = 0.003).

CONCLUSION

The complication rate of pulmonary angiography in patients with pulmonary hypertension is low. However, in severely ill patients with acute pulmonary hypertension, pulmonary angiography should be undertaken with extreme caution.

Review article: Effects of radiographic contrast media on the lung

The pulmonary adverse effects of intravascular use of water soluble radiographic contrast media (RCM) include bronchospasm, pulmonary oedema and increase in the pulmonary arterial blood pressure (Ppa). Symptomatic bronchospasm is rare but subclinical increase in airways resistance is common after intravascular injection of RCM. Experimental studies have demonstrated that the low osmolar ionic dimer ioxaglate can induce significant bronchospasm in comparison with other types of RCM. Histamine and endothelin, which are potent bronchoconstrictors and released in response to the administration of RCM, do not seem to mediate the bronchospastic effect of RCM. Pretreatment with corticosteroids or antihistamine does not appear to prevent RCM induced bronchospasm, but the administration of beta(2) adrenergic agonist can abolish this adverse effect. RCM induced pulmonary oedema can be secondary to endothelial injury causing an increase in the permeability of the microcirculation. It may also occur in patients with incipient cardiac failure, when large doses of RCM particularly of the high osmolar type are used. A rise in Ppa induced by RCM seems to be secondary to an increase in pulmonary vascular resistance through direct effects on the pulmonary circulation. Low osmolar non ionic monomers induce the least changes in the pulmonary circulation and should be the contrast media of choice for intravascular use in patients with pulmonary hypertension. The mechanisms responsible for the effects of RCM on airway resistance and pulmonary circulation remain unclear. Intrabronchial administration of high osmolar water soluble RCM is dangerous and can induce severe bronchial irritation and pulmonary oedema. Low osmolar RCM are well tolerated by the lungs following aspiration with minimal histological reaction.