Continuous recording of His bundle electogram during selective coronary cineangiography in man

Influence of low osmolality contrast media on electrophysiology and hemodynamics in coronary angiography: differences between an ionic (ioxaglate) and a nonionic (iohexol) agent

It has recently been suggested that the addition of sodium to low osmolality contrast media may reduce the incidence of ventricular fibrillation and conduction disturbances during coronary angiography. In a randomized, double blind study of 30 patients undergoing coronary angiography we therefore examined the electrophysiological and hemodynamic effects of the two low osmolality contrast media-ioxaglate (with sodium) and iohexol (without sodium). Standard ECG, aortic blood pressure, and His bundle electrocardiogram were recorded. The contrast media were well tolerated and no serious arrhythmias were observed. Both induced a transient decrement in systolic blood pressure and reduction in heart rate 10 s following contrast injection (all P less than 0.01). Ioxaglate prolonged the QT interval at 10 s (P less than 0.01) and also when analysed for the whole observation period (120 s) (P less than 0.05), whereas iohexol did not cause any significant changes in the QT-interval. The AH-interval was prolonged by ioxaglate at 10 s (P less than 0.01), but not altered by iohexol. Thus, other factors than osmolality and sodium content might contribute to QT prolongation, since only the contrast agents with sodium (ioxaglate) induced QT prolongation in this study.

Ventricular arrhythmias during coronary angiography in patients with angina pectoris or chest pain syndromes

Of 7,915 patients undergoing coronary angiography from 1978 to 1983, 39 (25 men and 14 women with a mean age of 57 years [range 37 to 79]) had sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) during the procedure. Nine patients had atypical chest pain and 30 had typical angina. Fifteen had had a previous myocardial infarction. One patient had a history of VT or VF. Electrocardiograms taken at rest revealed a prolonged QT interval in 14. A normal ejection fraction was found in 79%. Coronary angiography revealed that 10 patients had 3-vessel disease, 15 had 1- or 2-vessel disease and 14 had normal coronary arteries. The VT or VF was seen with injection of contrast medium into the right coronary artery in 24, the left coronary artery in 10 and vein bypass grafts in 5 patients. Of the episodes of VT or VF, 67% occurred after injection of contrast medium into a minimally diseased coronary artery. In patients in whom VT or VF occurred after injection into a minimally diseased coronary artery, the arrhythmia was preceded by bradycardia, usually with pronounced widening of the QRS and QT intervals. This response was significantly different from that in patients in whom VT or VF occurred after injection into a coronary artery with significant stenosis; in these patients, VT or VF was initiated by a single premature ventricular contraction on a T wave. VT or VF was successfully cardioverted in all instances, without further arrhythmias.

Changes in QTc interval induced with Renografin-76 and Hypaque-76 during coronary arteriography

Renografin-76 and Hypaque-76 are both recommended for coronary arteriography. Both have the same osmolality and iodine concentration, but differ in their calcium binding properties. After selective right or left coronary arteriography in patients, Renografin-76 caused significantly more prolongation of the QTc interval than did Hypaque-76. Less calcium binding in the Hypaque formulation is probably responsible for its lesser effect on the QTc interval. This study suggests, but does not prove, that Hypaque-76 is safer than Renografin-76 for coronary arteriography.

Symptomatic spontaneous paroxysmal AV nodal block due to localized hyperresponsiveness of the AV node to vagotonic reflexes

Two apparently healthy patients had recurrent syncope with documented paroxysmal AV block. In both patients the site of AV block was demonstrated to be in the AV node. Coronary angiography (in both patients) and sustained deep inspiration (one patient) reproducibly initiated episodes of paroxysmal AV nodal block (identical to spontaneous episodes). Atropine abolished further attempts of AV block induction. Vagal hyperresponsiveness was limited to the AV node, since the interventions provoking paroxysmal AV nodal block produced only appropriate sinus slowing. This syndrome reflects hyperresponsiveness of the AV node to vagotonic reflexes, and exists as a clinically significant entity producing recurrent syncope.

Sinus slowing produced by intracoronary arterial injections of hyperosmotic solutions in man

The effect of intracoronary arterial injections of normal saline, contrast agent, hyperosmotic glucose, and mannitol solutions on the sinus rate was studied in 18 patients. Sinus slowing was not produced by isosmotic saline (0.3 Osm. per kilogram of water) when injected into either coronary artery, whereas 76% Urografin (1.9 Osm. per kilogram of water), 20% glucose (1.3 Osm. per kilogram of water), and mannitol (1.2 Osm. per kilogram of water) decreased the sinus rate significantly (P less than 0.001). Among these solutions, Urografin with the highest osmolality produced the most marked sinus slowing, whereas no significant difference was detected between change in the sinus rate with hyperosmotic glucose and mannitol solutions (P greater than 0.5). Moreover, there was no significant difference between the degree of sinus slowing produced by intracoronary injections into the coronary artery of the side which the sinus node artery originated from and the slowing produced by contralateral injections with hyperosmotic solutions (P greater than 0.2). Therefore, it seems unlikely that this sinus slowing would be a result of a direct action on the sinus node including hypoxia and elevated perfusion pressure. Reflex-mediated parasympathetic stimulation may be operative.

Effects of coronary arteriography on atrioventricular conduction. Studies with His bundle electrography

The effect of coronary arteriography on atrioventricular (A-V) conduction was studied in 26 patients with the use of His bundle electrography. Slowing of atrioventricular conduction (prolonged A-H interval) was observed in all 26 pateints following either left or right coronary arteriography without a detectable change in the H-V interval. In four patients with left coronary preponderance in arterial distribution pattern, prolonged A-H inverval was produced only by injecting the contrast material into the left coronary artery. Conversely, in the remaining 22 patiens either with right preponderance or balanced distribution, prolongation of the A-H time was a result of opacification of the right coronary artery. The A-H interval at peak prolongation (133.9 +/- 18.7 [S.D.] msec.) was significantly higher than the control measurement (98.3 +/- 15.7 msec.) (P less than 0.0001). Prolongation of the A-H interval started around 4 seconds after the initiation of injection, reached its peak at an average of 7.7 seconds, and subsided within 20 seconds. When intracoronary injection of 6 ml. of normal saline was made in these 26 patients, no change was observed in the His bundle electrograms. On the other hand, hypertonic (20 per cent) glucose solution, when injected into coronary arteries, had an effect remearably similar to that of contrast material on A-V conduction. These findings suggest that prolonged A-H interval observed during coronary arteriography may be a result of osmotic effect of the contrast material, rather than hypoxia resulting from dilution of coronary blood flow.