Protection from digoxin-induced coronary vasoconstriction in patients with coronary artery disease by calcium antagonists.

Intravenous digoxin induces constriction of normal and stenotic coronary arteries in patients with coronary artery disease, which may lead to ischemic complications. We found that pretreatment with oral nisoldipine and intracoronary nitroglycerin neutralizes this digoxin-induced effect.

How to standardize vasomotor tone in serial studies based on quantitation of coronary dimensions?

In patients with coronary artery disease including those after coronary bypass graft operation and heart transplantation intervention studies based on serial quantitative coronary angiography, in part combined with intravascular ultrasound, are of increasing relevance. Since vasomotor tone of epicardial coronary arteries is influenced by a variety of factors, angiographic follow-up studies require standardization of coronary tone by induction of maximal dilation. We reviewed the effects of the most potent coronary vasodilatory drug groups, calcium antagonists and nitrocompounds, on coronary diameters. Intravenous or intracoronary injections of verapamil, diltiazem, nifedipine, nicardipine, and nisoldipine can cause profound coronary dilation which has been shown to be maximal with verapamil and nisoldipine. Shortcomings of calcium antagonists include short or unknown duration of action after bolus administration, severe drop in blood pressure, and lack of commercial availability of solutions for injection of many substances. Isosorbide dinitrate induces profound coronary dilation; however, after sublingual administration marked blood pressure decrease can occur, and the duration of action and ideal dose of intracoronary isosorbide dinitrate has not been investigated yet. Injections of molsidomine and its active metabolite, SIN-1, cause longlasting, reproducible, maximal coronary dilation, although only after a waiting period of at least 10 minutes; unfortunately, SIN-1 is only commercially available in France. Nitroglycerin induces reproducible maximal coronary dilation and is easy to administer sublingually or as intracoronary bolus injection with rapid onset of action and no major side effects. The short duration of action may require repeated administrations. To date, repeated intracoronary bolus injections of 0.1 mg nitroglycerin every 10 minutes seem to be the optimal known regimen for standardization of coronary vasomotor tone in serial angiographic studies. Further investigations in this field with old and new vasodilatory drugs are recommendable.

Comparative in-vitro validation of eight first- and second-generation quantitative coronary angiography systems.

BACKGROUND: It is known that first-generation quantitative coronary angiography (QCA) systems overestimate small vessel sizes owing to the point-spread function of the respective X-ray imaging chain. With second-generation systems new algorithms were introduced to correct for this source of error. OBJECTIVE: To evaluate the efficiency of the modified contour detection algorithms. METHODS: Six second-generation QCA systems (CMS, QANSAD, AWOS, CAAS II, Cardio 500, and Angioimage) were validated and compared with first-generation systems (CAAS and ARTREK). By using an arterial phantom consisting of stenotic and nonstenotic glass tubes (of diameters 0.5-5.0 mm) the accuracy and precision of each analysis system, as well as their additional accuracy and precision values for phantom diameters < or = 1.0 mm were determined. RESULTS: All systems had high accuracy and precision values, but first-generation systems overestimated small vessel diameters. With second-generation systems a significantly improved accuracy in the submillimeter range (an accuracy within +/-0.028 mm) was obtained. This improvement was accompanied by a moderate reduction in precision in the submillimeter range. CONCLUSION: The new algorithms of the second-generation QCA systems allow accurate and reliable measurements of small coronary dimensions and, therefore, precise analysis of coronary stenoses of moderate-to-high grade seems feasible with the improved accuracy of the new systems.

Comparison of different quantitative coronary analysis systems: ARTREK, CAAS, and CMS.

It has been known that the first generation quantitative coronary analysis systems overestimate small vessel sizes. In the 2nd generation the contour detection algorithms, e.g., of the new Cardiovascular Measurement System (CMS), were modified to correct for the limited resolution of the X-ray imaging chain. This study validated and compared the CMS with the well-known Coronary Angiography Analysis System (CAAS) and the vessel tracking program ARTREK in a phantom study and a clinical study. In addition, the influence of different acquisition media (cinefilm vs. digitally acquired angiograms) on the accuracy of quantitative analysis was examined. The phantom study comprised 19 stenotic or non-stenotic glass tubes with a diameter range from 0.54 mm to 4.9 mm. In the clinical study the mean diameters of 322 coronary segments were analysed and the results of the systems were compared among each other. The results of the phantom study were presented in terms of the mean difference (accuracy) between true and measured values. In the phantom study the overall accuracy of the CMS was -6 microns (ARTREK: 85 microns; CAAS: 35 microns) with an overestimation of small vessels of only -11 microns (ARTREK: 97 microns: CAAS: 51 microns). The clinical study showed that the CMS corrected the usually occurring overestimation of small coronary arteries and that the influence on the accuracy of different acquisition media is minor. Due to the modified algorithms the new CMS is able to measure coronary diameters down to 0.5 mm accurately. Therefore, the CMS seems to provide more precise measurements in quantitative analysis of small coronary diameters than CAAS and ARTREK.

[Digoxin-induced constriction of epicardial coronary vessels in patients with coronary heart disease: reversibility by nitrates]. / Digoxin-induzierte Konstriktion epikardialer Koronargefässe bei Patienten mit koronarer Herzkrankheit: Reversibilität durch Nitrate.

Heart diseases requiring glycoside therapy are often associated with coronary artery disease. This study evaluated quantitatively the effect of an intravenous bolus injection of digoxin (0.8 mg) on diameters of epicardial coronary arteries in 11 patients with coronary artery disease. Coronary angiograms were taken up to 30 min following intravenous administration of glycosides. The maximum decrease in mean diameters of angiographically normal coronary segments was 10.0 +/- 3.5% (p < or = 0.001) compared to control. Maximum reduction in minimal diameters of stenotic segments was 22.1 +/- 13.1% (p < or = 0.001). This vasoconstriction could be reversed with nitroglycerin. Thus, intravenous administration of digoxin induces vasoconstriction of normal and stenotic coronary arteries, which could cause ischemic complications in the presence of high-grade stenoses. Since digoxin-induced vasoconstriction could be reversed with nitroglycerin, concomitant vasodilator therapy is recommended.

Quantitative angiographic follow-up studies on the development of coronary artery disease: which coronary segments should be analyzed? Experience from INTACT.

Angiographic follow-up studies on the evolution of coronary artery disease are of increasing relevance. It has still to be evaluated which coronary segments are predominantly involved in the process of atherosclerosis and, thus, should be preferably included in the analysis. Therefore, the correlation of progression and regression of coronary disease with the diameter and location (proximal, mid or distal) of coronary segments was investigated from the data of the INTACT-study, in which 25 different coronary segments were defined including anatomic variants of rather distal segments. In 348 patients with coronary artery disease, standardized coronary angiograms were repeated within 3 years and were quantitatively analyzed (CAAS). In 1063 coronary stenoses (% diameter stenosis > 20%) compared from both angiograms, progression and regression were not influenced by diameter nor location of arterial segments. In the follow-up angiograms, the number of new lesions (stenoses and occlusions) per coronary segment differed with regard to segment diameter (> 3 mm: 64/1125 (6%); 2-3 mm: 139/1967 (7%); < 2 mm: 44/1756 (2%); p < 0.001) and location of segments (proximal: 86/1285 (7%); mid: 84/1193 (7%); distal: 77/2370 (3%); p < 0.001). Out of 77 distal new lesions, only 25 (32%) were found in segments < 2 mm in diameter. Since the absolute number of new lesions was high in distal coronary segments, but low in segments with diameters < 2 mm, angiographic follow-up studies should analyze coronary segments at any location, but may neglect segments with diameters smaller than 2 mm.

Angioplasty of subacute and chronic total coronary occlusions: success, recurrence rate, and clinical follow-up.

Angioplasty of single total, subacute, or chronic coronary occlusions was performed in 90 patients. It was successful in 54 occlusions (60%), in 77% of those less than 6 weeks old, and in 44% of those of greater than 6 weeks' duration (p less than 0.005). All procedures were uneventful. Control angiography was performed in 53 (98%) patients with successful angioplasty after an average interval of 97 +/- 53 days. Stenosis had recurred in 16 patients (30%). During a follow-up period of 36 +/- 13 months, three patients died, five patients underwent coronary bypass operation, and 10 had reangioplasty. Despite an additional late angiographic recurrence of stenosis in seven patients, 36 patients revealed angiographic long-term success. In the 46 nonoperated patients, angina pectoris and exercise stress tests were substantially improved. Thus angioplasty of subacute and chronic total coronary occlusions is an uneventful procedure, the success rate depending on the duration of the occlusions. Despite a high angiographic recurrence rate, the angiographic and clinical long-term results are favorable.