Biomedical subjects

I Knop

Publications and source records attributed to I Knop.

6 recordsLinked to original sources

PubMed1990

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.

Angiography↗

PubMed1990

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.

Adult↗

PubMed1989

Coronary vasodilation with nitrocompounds--is there a maximum?

The maximal extent of the dilation of epicardial coronary arteries attainable with nitro-compounds was investigated in 12 patients with coronary artery disease. Before and 5, 10, 15, 19, 60 and 64 min after onset of a 4-min-intravenous infusion of 0.025 mg SIN-1/kg bodyweight coronary angiograms were performed in identical projection; simultaneously, the mean pulmonary wedge pressure (PWP) was measured. At 15 and 60 min, 0.8 mg nitroglycerin (NTG) were additionally administered as sublingual spray. Mean diameters of angiographically normal coronary segments were analyzed with the computer-assisted contour detection system CAAS; they increased by an average maximum of 29 +/- 5% prior to NTG (p less than 0.001). PWP decreased from 9.2 +/- 3.1 mmHg to an average minimum of 4.3 +/- 1.6 mmHg (p less than 0.01) prior to NTG. Neither of these SIN-1-effects was significantly augmented by additional NTG: at 19 min coronary dilation amounted to 28 +/- 7% (p less than 0.001), PWP to 3.9 +/- 1.0 mmHg (p less than 0.01). At 60 min coronary dilation still amounted to 24 +/- 8% (p less than 0.001), PWP to 6.2 +/- 2.5 mmHg (p less than 0.05). By the second administration of NTG the maximal effects attained before could be reproduced: coronary dilation 28 +/- 8% (p less than 0.001), PWP 4.6 +/- 2.2 mmHg (p less than 0.01). Thus, the dilation reserve of epicardial coronary arteries for nitrocompounds is approximately 30% on average. These results suggest the possibility of a reproducible maximal activation of the enzyme guanylate cyclase which seems to be the mediator of the nitro-compound-induced vasodilation.

Administration, Sublingual↗

PubMed1989

Correlation between isosorbide dinitrate plasma levels and coronary vasodilation after chewing capsules.

In 10 patients with coronary artery disease coronary angiograms were performed in identical projections before and 5, 10 and 15 min after sublingual administration of two chewing capsules with 5 mg of isosorbide dinitrate (ISDN) each. Simultaneously, blood samples were taken for gas-chromatographical determination of nitrate plasma levels. The average ISDN plasma levels amounted to 138 +/- 73 ng/ml, 102 +/- 76 ng/ml and 62 +/- 34 ng/ml in the fifth, tenth and fifteenth min, resp. In the fifteenth min significant isosorbide mononitrate plasma levels (greater than 70 ng/ml) were found only in three patients. Mean diameters of angiographically normal coronary segments were measured with the automatic edge detection system CAAS; they increased by an average of 20 +/- 10%, 26 +/- 11%, and 27 +/- 13% (p less than 0.001) in the fifth, tenth and fifteenth min, resp. Due to hysteresis of the coronary dilation in relation to ISDN plasma levels no significant correlation was found between these parameters. The minimal diameters of seven of 10 coronary stenoses analyzed in seven patients reacted with a maximal increase of 23%-98%. Thus, ISDN chewing capsules may be preferable for rapid and prolonged relief of anginal attacks as well as for potent dilation of epicardial coronary arteries as desired during angiography.

Administration, Sublingual↗

PubMed1989

Drug plasma levels and coronary vasodilation after isosorbide dinitrate chewing capsules.

Five, ten and fifteen min after sublingual administration of 10mg isosorbide dinitrate (ISDN) in chewing capsules, in 10 patients with coronary artery disease, ISDN plasma levels were correlated with the dilation of epicardial coronary arteries as well as with changes in aortic blood pressure and heart rate. Due to the rapid and extensive drug absorption, maximal ISDN plasma levels averaged 138 +/- 73 ng ml-1 and were already obtained after 5 min; they declined to 102 +/- 76 and 62 +/- 34 ng ml-1 in the 10th and 15th min respectively. In 7 patients isosorbide mononitrate plasma levels were still negligibly low (less than 30 ng ml-1). Mean diameters of 'normal' coronary segments increased by an average of 20 +/- 10%, 26 +/- 11% and 27 +/- 13% (P less than 0.001) at 5, 10 and 15 min respectively compared to control. The maximal drop in systolic aortic pressure (147 +/- 19 to 115 +/- 15 mmHg; P less than 0.01) as well as the maximal increase in heart rate (66 +/- 4 to 80 +/- 11 beats min-1; P less than 0.01) were observed in the 15th min; diastolic aortic pressure and double product remained constant. Due to the long persistence of coronary dilation and haemodynamic changes, none of these drug effects correlated significantly with the ISDN plasma levels. In addition, the minimal diameters of 10 coronary stenoses were measured in 7 patients; with ISDN 7 stenoses showed dilation ranging from 23% to 98%.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Sublingual↗

PubMed1988

[Urinary diversion following radical cystectomy: ileal conduit or ileal replacement bladder?].

Among those patients who have undergone radical cystoprostatectomy in the Department of Urology at the Municipal Hospital of Kassel (FRG) since 1985, 57 received a continent ileal bladder anastomosed to the membranous urethra. In a retrospective study intra- and postoperative complications, late complications and prognosis of the tumor disease of these patients were compared with those who had an ileum conduit from 1983 to 1988 (n = 44). The intra- and postoperative complications were nearly identical. During the further postoperative course, patients with a continent ileal bladder may present with strictures at the anastomosis of the ileal bladder and urethra, incomplete voiding with residual urine, secretion of water by the mucosa, and metabolic disturbances because of absorption of substances usually eliminated with the urine. The latter decreases with time as the glandular epithelium of the ileal mucosa changes into mucigenous cells with villous atrophy. The danger of local tumor recurrence and metastasis is the same in patients with an ileal bladder and an ileal conduit.

Follow-Up Studies↗