Platelet aggregation in response to collagen and thrombin reliably detects the ingestion of low-dose aspirin.

The exposure of blood donors to aspirin is not reliably excluded by pharmacokinetic measurements due to the irreversible effects of aspirin which persist even after elimination of aspirin and its metabolites from plasma. Tests of platelet functions do overcome this deficit, but are usually limited by substantial inter-individual variability of parameters of platelet function. We have evaluated platelet aggregation ex vivo in 20 aspirin-treated (100 mg single oral dose/day) patients in comparison with a control group of 20 aspirin-free donors. The results demonstrate a significant reduction in the collagen(2.5 micrograms/ml)-induced platelet aggregation by aspirin treatment, whereas thrombin(50 mumol/l TRAP-6)-induced platelet aggregation was not affected at all. Assessment of collagen-induced platelet aggregation relative to platelet responses of the same subject elicited either by thrombin or by a combination of collagen and thrombin does substantially improve the reliability of functional assays of aspirin.

Risk factors of cardiac arrest in arrhythmogenic right ventricular dysplasia.

Arrhythmogenic right ventricular dysplasia is an important cause of ventricular arrhythmia with a potential risk of sudden cardiac death in a young population. In order to define risk factors of cardiac arrest, angiographic and electrophysiological data from 60 patients with angiographically documented arrhythmogenic right ventricular dysplasia (of whom 20 also had spontaneous non-sustained ventricular arrhythmias, 27 sustained ventricular tachycardia and 13 suffered cardiac arrest with documented ventricular fibrillation before resuscitation) were analysed. There were no statistically significant differences in right ventricular volume, global right ventricular ejection fraction (RVEF), right ventricular structure, mean age at the time of diagnosis and angiographic left ventricular contraction abnormalities in the subgroups of patients with different forms of spontaneous arrhythmias. Only in a subgroup of patients with cardiac arrest and inducible sustained ventricular tachycardia did right ventricular volume (P < 0.05), ejection fraction (P < 0.001) and the amount of structural changes (P < 0.01) reveal significant results. A subgroup of patients with structural alterations and a low level of right ventricular function is at a high risk of cardiac arrest, although strenuous exercise and sport remain most important risk factors.

Selective right ventricular angiography in apparently idiopathic ventricular fibrillation.

The definition of underlying heart disease in apparently idiopathic ventricular fibrillation seems to be important in regard to prognosis and choice of therapy. From October 1989, until August 1993, cardiac arrest due to the documented ventricular fibrillation occurred in eight consecutive patients with normal results on clinical examination, normal echocardiography, and normal or apparently nonspecific electrocardiogram (ECG) findings. Complete invasive investigations, including selective right ventricular angiography, were done; regional hypokinesia and segmental bulging of the right ventricle were found in seven patients (88%). Arrhythmogenic right ventricular dysplasia was suspected in these patients, although endomyocardial biopsy was not performed. After the finding of localized right precordial QRS prolongation of more than 110 ms in November 1993 in five patients, a retrospective, a more precise approach to QRS duration in standard ECG supported this diagnosis. Selective right ventricular angiography is of great help in identifying underlying heart disease in patients with apparently idiopathic ventricular fibrillation, and confirms ECG findings.

[Incidence and significance of morphologic and morphometric variants in selective right ventricular angiography in diagnosis of arrhythmogenic right ventricular disease]. / Häufigkeit und Bedeutung morphologischer und morphometrischer Varianten der selektiven rechtsventrikulären Angiographie in der Diagnostik der arrhythmogenen rechtsventrikulären Erkrankung.

BACKGROUND: In arrhythmogenic right ventricular disease it is difficult to find an imaging technique not only to suppose but to diagnose this disease. PATIENTS AND METHOD: In order to assess the value of selective right ventricular angiography in 104 patients with arrhythmogenic right ventricular disease (n = 53), WPW-syndrome (n = 2), sarcoidosis (n = 1), atrial septum defect (n = 8), dilative cardiomyopathy (n = 8), mitral valve disease (n = 17) and normal patterns (n = 15) right ventricular angiography was performed in biplane 30 degrees RAO/60 degrees LAO projection. Quantitative criteria such as RVEDVi, RVEF, regional wall motion in infundibular, inferior, apical and anterior segments and qualitative criteria such as deep horizontal fissures in trabecular hypertrophy, "pile d'assiettes" phenomenon and enddiastolic bulges with loss of trabecular structure were analysed. RESULTS: After extensice statistical analysis enddiastolic bulges with loss of trabecular structure and in less circumstance segmental contraction impairment of the right ventricle are the most valuable angiographic signs in order to diagnose ARVD. CONCLUSION: The best definition of arrhythmogenic right ventricular disease is obtained by extensive angiographic analysis with measurement of oxygen saturation and pressure curves in different positions, coronary angiography and biventricular angiography in order to distinguish between some in regard to right ventricular involvement similar cardiac entities.

Risk assessment in nonischemic ventricular arrhythmia by left and right ventriculography.

Ventricular fibrillation and sudden death are rare phenomena in nonischemic ventricular arrhythmia, particularly in arrhythmogenic right ventricular cardiomyopathy. In most instances electrophysiologic studies help to assess the risk of sudden death, but sometimes programmed ventricular stimulation is unsuccessful. Among 48 patients with ventricular fibrillation (n = 9) and sustained (n = 25) and nonsustained (n = 19) ventricular tachycardia, invasive and noninvasive diagnostic tests (coronary angiography, biventricular angiography, programmed ventricular stimulation, and echocardiography) were performed to obtain more information about the underlying heart disease. In 43 patients (90%) arrhythmogenic right ventricular cardiomyopathy was diagnosed with segmental hypokinesia (n = 31) and diffuse hypokinesia (n = 12) of the right ventricle. In patients with documented ventricular fibrillation, the right ventricular ejection fraction was lower (30.8% vs 47.8% and 45.9%, respectively) and multisegmental contraction impairment of the right ventricle was significantly more frequent (p less than 0.001). Additional left ventricular abnormalities and right ventricular dilatation were not significant parameters for identifying high-risk patients. In addition to programmed ventricular stimulation, quantitative analysis of the results of right and left ventricular angiography contributes to risk assessment in patients with nonischemic ventricular arrhythmia.

Reproducible uniform coronary vasomotor tone with nitrocompounds: prerequisite of quantitative coronary angiographic trials.

In quantitative analysis of repeated coronary angiograms, a variable vasomotor tone of the epicardial coronary arteries may influence the accuracy of the results. Therefore, we evaluated the extent and reproducibility of coronary artery dilation with nitrocompounds. In 32 patients with coronary artery disease, the vasodilatory response of angiographically normal coronary segments to different nitrocompounds was analyzed with the computer-assisted contour detection system CAAS. Twenty patients received 5 mg or 10 mg of isosorbide dinitrate sublingually. After 10 to 15 min, a maximal diameter increase was measured with an average of 16 +/- 11% (5 mg: P less than 0.01) and 28 +/- 13% (10 mg: P less than 0.001) from control. Another 12 patients received 0.025 mg per kg body weight of SIN-1, the active metabolite of molsidomine, as an intravenous infusion over 5 min. A comparable maximal dilation (29 +/- 5%; P less than 0.001) occurred after 10 to 15 min and could not be enhanced further with 0.8 mg nitroglycerin administered sublingually (28 +/- 7%; n.s.). One hour after square root of Sin-1, coronary dilation was still 24 +/- 8% (P less than 0.001 compared with control), and 0.8 mg of nitroglycerin sublingually reestablished the previous maximal dilation of 28 +/- 8%. We conclude that high doses of nitrocompounds induce a reproducible maximal coronary dilation that eliminates a substantial source of error in quantitative analysis of repeated coronary angiograms. At present, sublingual administrations of either 10 mg isosorbide dinitrate once or 0.8 mg nitroglycerin repeatedly seem to represent the easiest practicable modes to achieve maximal coronary vasodilation for an adequate period.

Elimination of variable vasomotor tone in studies with repeated quantitative coronary angiography.

In quantitative coronary angiographic studies, unintentional changes of coronary vasomotor tone may have a significant influence on the coronary artery diameters, thereby increasing the variability in the measurements. To obtain objective data on these measurement variabilities, two protocols were designed to assess the influences of ionic and nonionic radiographic contrast media on the mean diameters of angiographically normal coronary arteries. The vessel sizes were determined with the CAAS using automated edge detection techniques. In 21 patients (study no. I), coronary angiograms were taken in identical angiographic projections before (control), and immediately following several (at average 7) subsequent diagnostic dye injections administered over a period of about 7 min. The ionic contrast agent diatrizoate 76% induced a coronary dilation of 19 +/- 7% (mean +/- s.d., p less than 0.001; n = 10); the nonionic agent iopromide 370 increased the coronary artery diameters by only 6 +/- 4% (p less than 0.01; n = 11). In another 11 patients (study no. II) coronary angiograms were obtained using the nonionic contrast medium iopamidol 300 at 5, 8, 10 and 11 min after the control acquisition; this protocol was repeated in the same patients with diatrizoate 76%. With iopamidol, coronary diameter changes were not significant at any time; with diatrizoate, however, coronary dilation was measured at 10 min (2 +/- 2%; p less than 0.01) and at 11 min (10 +/- 3%; p less than 0.001). In a third study it was tested, whether standardization of coronary vasomotor tone (e.g. in coronary angiographic follow-up studies) is possible by the induction of a reproducible maximum coronary dilation with nitrocompounds. In 12 patients, the mean diameters of angiographically normal coronary segments were analyzed before and at various times after i.v. administration (over 4 min) of 0.025 mg SIN-1/kg bodyweight. Coronary dilation was maximal at 10 or 15 min after the onset of the SIN-1-infusion (29 +/- 5%; p less than 0.001). 0.8 mg nitroglycerin given s.l. at 15 min did not further dilate the coronary arteries (28 +/- 7%). One hour after SIN-1, coronary dilation still amounted to an average of 24 +/- 8% (p less than 0.001) and became 'maximal' again, when 0.8 mg nitroglycerin was again administered sublingually (28 +/- 8%; p less than 0.001). In conclusion, short-term variability of coronary vasomotor tone induced by ionic radiographic contrast media can be eliminated by the use of nonionic contrast agents and observation of injection intervals of at least 2 min. In quantitative coronary angiographic follow-up studies, as well as during acute interventions (e.g., PTCA), identical baseline vasomotor tone can be achieved by induction of the maximal coronary dilation using nitrocompounds.