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PubMed2002

Mechanism of inducible regional dysfunction during dipyridamole stress.

BACKGROUND: We hypothesized that increased myocardial oxygen demand resulting from hypotension and reflex tachycardia unmasking a reduced endocardial myocardial blood flow (MBF) reserve is the mechanism of dipyridamole-induced regional dysfunction in chronic coronary artery disease. METHODS AND RESULTS: Ameroid constrictors were placed around the proximal coronary arteries and their major branches in 15 dogs to create chronic coronary stenosis. Seven days later, radiolabeled microsphere-derived MBF and 2-dimensional echocardiography-derived percent wall thickening (%WT) were measured at rest and after 0.56 mg/kg dipyridamole. Dipyridamole caused an increase (mean, 21%) in the rate-pressure product secondary to reflex tachycardia resulting from mild systemic hypotension. %WT in myocardial segments with an endocardial MBF reserve (dipyridamole/resting MBF) of 1.5 to 2.5 (n=35) did not change after dipyridamole, whereas it decreased in segments with an endocardial MBF reserve of <1.5 (n=30) and increased in those with an endocardial MBF reserve of > or =2.5 (n=45) (P<0.05). Most (80%) segments with endocardial MBF reserve of <1.5 and 14% with an endocardial MBF reserve of 1.5 to 2.5 showed inducible dysfunction after dipyridamole, whereas none of the segments with an endocardial MBF reserve of > or =2.5 showed this finding. A sigmoid relation (y=-6.74/[1+exp (19.9. [x-1.84])]+1.35. x, r=0.93, P<0.0001) was noted between endocardial MBF reserve and Delta%WT. In contrast, neither the epicardial MBF reserve nor the endocardial/epicardial MBF ratio during hyperemia was associated with inducible regional dysfunction. CONCLUSIONS: Increased myocardial oxygen demand resulting from hypotension and reflex tachycardia unmasking a reduced endocardial MBF reserve is the primary mechanism of dipyridamole-induced regional dysfunction in chronic coronary artery disease.

Animals↗
PubMed1981

Salvage of ischemic myocardium by dipyridamole in the conscious dog.

We investigated the effect of i.v. dipyridamole, a potent small-vessel coronary vasodilator, on myocardial infarct size in conscious dogs. Dipyridamole, 7-9.7 microgram/kg; 15 dogs) or saline (15 dogs) was infused for 6 hours beginning 10 minutes after acute permanent occlusion of the mid-circumflex coronary artery. After sacrifice, 48 hours after occlusion, stereoscopic postmortem angiography was used to define the mass of the occluded coronary bed. Infarct size was determined by planimetry of weighed, unstained left ventricular slices. Dipyridamole produced a striking reduction in mean infarct mass compared with control (3.1 g vs 13.2 g, p less than 0.001), while mean occluded bed mass was similar (30.3 g vs 32.7 g, NS). As a percentage of the occluded bed, mean infarct size was reduced from 36.8% to 8.6% ( p less than 0.001). Mean arterial blood pressure declined approximately 10% after dipyridamole. Heart rate and left atrial pressure did not change significantly. Collateral blood flow, measured with 8- mu radioactive microspheres, increased in all regions during dipyridamole infusion. The infarct center and border regions had sustained increases over 6 hours of 23-80%, while nonischemic regions demonstrated a diminishing response over time, with a large (98-125%) increase 10 minutes after infusion and a smaller (22-25%) increase 6 hours later. Although antiplatelet or local metabolic effects cannot be excluded, the myocardial salvage produced by dipyridamole was most likely due to the increase in collateral blood flow.

Animals↗
PubMed1985

Intrinsic washout rates of thallium-201 in normal and ischemic myocardium after dipyridamole-induced vasodilation.

Infusion of dipyridamole has been suggested as an alternative to exercise stress for myocardial perfusion imaging for detection of ischemia, but the mechanism and significance of thallium-201 (201Tl) redistribution after administration of dipyridamole are uncertain. If disparate intrinsic cellular efflux rates of 201Tl from normal and relatively underperfused myocardium in response to dipyridamole-induced vasodilation were observed, this could explain delayed 201Tl redistribution. We investigated eht effect of an intravenous infusion of 0.15 mg/kg dipyridamole on the intrinsic myocardial washout rate of 201Tl as measured with a gamma-detector probe after intracoronary injection (50 muCi) of the radionuclide in open-chested anesthetized dogs. In six normal dogs the t 1/2 for intrinsic 201Tl washout from the myocardium was 89 +/- 11 min (SE) at control conditions and became more rapid at 59 +/- 10 min (p = .0001) after dipyridamole. This corresponded to a significant increase in microsphere-determined epicardial (0.95 +/- 0.11 to 2.23 +/- 0.46 ml/min/g; p = .01) and endocardial (0.86 +/- 0.10 to 1.53 +/- 0.27; p = .029) flows. In 12 dogs with a critical coronary stenosis, the 201Tl intrinsic washout rate slowed from 70 +/- 5 to 104 +/- 6 min (p = .0001) after production of the stenosis and slowed even further to 169 +/- 21 min (p = .003) after dipyridamole.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Electrophysiologic effects of dipyridamole on atrioventricular nodal conduction and supraventricular tachycardia. Role of endogenous adenosine.

Exogenous adenosine has been shown to have potent electrophysiologic effects and antiarrhythmic properties within the atrioventricular (AV) node. Endogenous adenosine, a nucleoside with an increased release signaled by ischemia and hypoxia, is not believed to exert significant effects during homeostatic conditions. Recent experimental evidence suggests, however, that under normoxic conditions, the amount of adenosine released may be sufficient to mediate some of its physiologic effects. This study was designed to test the hypothesis that in humans the electrophysiologic effects of endogenously released adenosine on AV nodal conduction can be demonstrated under normoxic conditions by inhibiting uptake and degradation of the nucleoside. In the first protocol, the effects of intravenous dipyridamole (0.56 mg/kg bolus i.v., 5 micrograms/kg/minute infusion), a nucleoside-transport blocker that elevates endogenous plasma levels of adenosine, on AV nodal conduction were evaluated in seven patients. At a constant atrial paced cycle length, dipyridamole increased the AH interval from 110 +/- 19 to 164 +/- 26 msec, p = 0.002 (+/- SEM). Aminophylline (5.6 mg/kg i.v.), a competitive antagonist of adenosine, completely reversed the effects of dipyridamole on AV nodal conduction. Similarly, dipyridamole increased the cycle length at which pacing-induced AV nodal Wenckebach occurred, from 348 +/- 31 (control) to 388 +/- 33 msec (dipyridamole) (p = 0.002). In a second protocol, the effects of intravenous dipyridamole were evaluated in another group of six patients who had supraventricular tachycardia (SVT) in which the AV node was part of the reentrant circuit.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗
PubMed1991

Transesophageal Doppler echocardiography evaluation of coronary blood flow velocity in baseline conditions and during dipyridamole-induced coronary vasodilation.

Transesophageal echocardiography allows the evaluation of proximal coronary artery anatomy and coronary blood flow velocity (CBFV). To assess the potential of transesophageal echocardiography in evaluating CBFV and its variations induced by coronary-active drugs, we studied 15 patients by high-quality pulsed wave Doppler recordings of CBFV. In these patients, transesophageal Doppler evaluation of CBFV was performed before, 2 minutes after cessation of dipyridamole infusion (0.56 mg/kg in 4 minutes), and 2 minutes after aminophylline infusion (240 mg injected 4 minutes after cessation of dipyridamole infusion). The following CBFV parameters were evaluated at each of the three steps of the study protocol: maximal and mean diastolic velocities and maximal and mean systolic velocities. Furthermore, the following indexes of coronary flow reserve were evaluated: the ratio between maximal diastolic velocity recorded after and before dipyridamole administration and the ratio between mean diastolic velocity recorded after and before dipyridamole administration. Nine of the 15 patients had a normal left anterior descending coronary artery (group A), whereas the remaining six had significant (less than or equal to 75%) stenosis (group B). In group A patients, all CBFV parameters increased significantly during dipyridamole infusion and returned to near baseline values after aminophylline infusion. In group B patients, on the other hand, none of the CBFV parameters increased after dipyridamole infusion. Dipyridamole/baseline maximal diastolic velocity and mean diastolic velocity ratios were, respectively, 3.22 +/- 0.96 and 3.04 +/- 0.88 in group A and 1.46 +/- 0.45 (p less than 0.01 versus group A) and 1.48 +/- 0.49 (p less than 0.01 versus group A) in group B patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Flow Velocity↗
PubMed1991

Dipyridamole echocardiography test. A new tool for detecting jeopardized myocardium after thrombolytic therapy.

BACKGROUND: We wished to assess whether dipyridamole echocardiography test (DET) can detect jeopardized myocardium after thrombolytic therapy. METHODS AND RESULTS: Seventy-six consecutive patients with a first acute myocardial infarction (AMI) were treated with 2 million IU urokinase i.v. within 4 hours of the onset of AMI and underwent high-dose (as much as 0.84 mg/kg over 10 minutes) DET 8-10 days after AMI. The results were correlated to the anatomy of the infarct-related vessel (IRV). In patients with positive DET, we evaluated the wall motion score index (WMSI; a semiquantitative integrated estimation of extent and severity of the stress-induced dyssynergy). WMSI was derived by summation of individual segment scores divided by the number of interpreted segments. In a 13-segment model, each segment was assigned a score ranging from 1 (normal) to 4 (dyskinetic). Fifty-three patients had positive results on DET. Of these, 42 had dipyridamole-induced new wall motion abnormalities (WMAs) confined to the infarct zone or adjacent segments. In these patients, mean WMSI increased from 1.46 +/- 0.26 (at resting conditions) to 1.73 +/- 0.35 (at peak dipyridamole) (p less than 0.01), whereas no significant change was detected in negative patients (1.6 +/- 0.34 versus 1.57 +/- 0.34, p = NS). Coronary angiography showed a patent IRV (TIMI grade 2 or 3) in 53 patients and no or minimal reperfusion (TIMI grade 0 or 1) in 23 patients. A patent IRV with critical residual stenosis was found in 35 of 42 patients with dipyridamole-induced WMAs in the infarct zone and in 18 of 34 patients without WMAs (p less than 0.05). Among the 23 patients with occluded IRVs, nine had collateral flow to the distal vessel; six of these had a positive DET. Thus, the sensitivity and specificity for identifying a critically stenotic but patent IRV or the presence of a collateral-dependent zone were 66% and 93%, respectively. In a subset of nine patients with a positive DET in the infarct zone or adjacent segments, DET and a control coronary angiography were repeated 1-3 months after an angiographically successful (residual stenosis, 50% or less) coronary angioplasty in the IRV. The repeat DET was negative in eight patients (all with patent IRV at control angiography) and again positive in one patient, who showed restenosis at angiography. The WMSI, at resting conditions was similar before and after angioplasty, whereas it differed significantly at peak dipyridamole (1.7 +/- 0.2 versus 1.4 +/- 0.2, p less than 0.01). CONCLUSIONS: DET can identify the anatomy of the IRV, and dipyridamole-induced WMAs within the infarct zone detect regions with jeopardized myocardium that may benefit from intervention.

Coronary Angiography↗
PubMed1994

Short-term cholesterol lowering decreases size and severity of perfusion abnormalities by positron emission tomography after dipyridamole in patients with coronary artery disease. A potential noninvasive marker of healing coronary endothelium.

BACKGROUND: Cholesterol lowering over 1- to 3-year trials is associated with modest regression or no progression of focal coronary artery stenoses compared with progression in controls, a decrease in cardiac events proportionately more than the modest improvement in percent stenosis, and in experimental animals improved endothelial-mediated coronary vasodilation. METHODS AND RESULTS: Accordingly, we hypothesized that there would be improvement in size and severity of perfusion abnormalities by rest-dipyridamole positron emission tomography (PET) imaging in a randomized intensive cholesterol-lowering trial with each patient studied after a baseline control period, a 90-day intensive cholesterol-lowering treatment, and a final control period off cholesterol-lowering regimens. Completely automated, objective measures of size and severity of perfusion abnormalities on rest-dipyridamole PET images were made by computer algorithm in 12 patients with coronary artery disease. There were statistically significant decreases (improvement) in size and severity of perfusion abnormalities by rest-dipyridamole PET on comparison of baseline control with perfusion abnormalities after intensive 90-day cholesterol lowering and significant increases (worsening) in size and severity after the final control period, respectively, as follows. (1) The percent of left ventricle outside 2.5 SD of normal values on the dipyridamole-to-rest ratio image of normalized counts was 22 +/- 20% after the initial control period, 13 +/- 14% after the treatment period, and 26 +/- 22% after the final control period with a significant decrease (improvement) occurring between the initial control and treatment periods (P = .02) and an increase (worsening) occurring between the treatment and final control periods (P = .009). (2) The percent of left ventricle with a ratio of < or = 0.66 in the dipyridamole-to-rest ratio image of normalized counts was 11 +/- 13% after the initial control period, 5.8 +/- 10% after the treatment period, and 14 +/- 19% after the final control period with a significant decrease (improvement) occurring between the initial control and treatment periods (P = .04) and an increase (worsening) occurring between the treatment and final control periods (P = .02). (3) The myocardial quadrant on the polar display with the lowest average activity expressed as a percent of maximal activity was 0.81 +/- 0.18 after the initial control period, 0.87 +/- 0.014 after the treatment period, and 0.77 +/- 0.23 after the final control period with significant improvement occurring between the initial control and treatment periods (P = .05) and worsening occurring between the treatment and final control periods (P = .05). CONCLUSIONS: These results suggest that relatively short-term, intensive cholesterol lowering over 90 days improves myocardial perfusion capacity before anatomic regression of stenoses occurs and that such improvement, or deterioration after withdrawal of lipid-lowering treatment, can be followed noninvasively by dipyridamole PET, reflecting the integrated flow capacity of the entire coronary arterial/arteriolar vascular system affected by diffuse atherosclerosis.

Adult↗
PubMed1986

Effect of hypercholesterolemia on vascular reactivity in the rabbit. II. Influence of treatment with dipyridamole on endothelium-dependent and endothelium-independent responses in isolated aortas of control and hypercholesterolemic rabbits.

The effects of cholesterol-feeding in the presence of dipyridamole (0.60 g daily) on contractile responses and on endothelium-dependent and endothelium-independent relaxations in isolated rabbit aortas are described. The investigations were performed simultaneously with those described in Part I (Circ Res 1986; 58:552-564), where the effects of cholesterol feeding on vascular reactivity in rabbit arteries (n = 8 in each group) selected at random from the same group of animals was studied. In the hypercholesterolemic rabbits treated with dipyridamole for 8 or 16 weeks, both the increases in plasma cholesterol and the formation of fatty streaks were significantly less pronounced than in the hypercholesterolemic rabbits not receiving the drug. Segments of the isolated arteries were mounted in organ chambers for isometric tension recording. The contractions caused by acetylcholine, prostaglandin F2 alpha, norepinephrine, clonidine, and serotonin and the endothelium-independent relaxations to nitroglycerin were not significantly altered by the hypercholesterolemia in rabbits treated with dipyridamole, even after 16 weeks of treatment. Thus, the decreased responses to norepinephrine, clonidine, and nitroglycerin and the augmented responses to serotonin noted in aortas of hypercholesterolemic rabbits in Part I were absent in the dipyridamole-treated hypercholesterolemic animals. The endothelium-dependent relaxations to ATP and acetylcholine were not affected after 8 weeks of hypercholesterolemia in presence of dipyridamole, while after 16 weeks the relaxations to ATP and acetylcholine were attenuated only in the more severely affected arteries. The effects of hypercholesterolemia + dipyridamole on endothelium-dependent relaxations were significantly less pronounced than those induced by hypercholesterolemia alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2005

Role of adenosine and nitric oxide on the mechanisms of action of dipyridamole.

BACKGROUND AND PURPOSE: The combination of dipyridamole and aspirin has been shown to be more effective than aspirin alone in the secondary prevention of stroke. Dipyridamole may act by inhibiting adenosine uptake, thus potentiating its actions. Dipyridamole also inhibits cGMP-specific phosphodiesterases (PDE) and, through this mechanism, could potentiate cGMP-mediated actions of nitric oxide. METHODS: To define the mechanism of action of dipyridamole, we studied the local vascular effects of adenosine, acetylcholine (NO-mediated dilation), and nitroprusside (cGMP-mediated dilation) in a double-blind study after treatment with dipyridamole/aspirin (200 mg dipyridamole/25 mg aspirin twice a day) or aspirin control for 7 days in 6 normal volunteers. Vasodilators were administered into the brachial artery in the nondominant arm in random order and forearm blood flow (FBF) was measured by venous occlusion plethysmography. RESULTS: Adenosine at a dosage of 125 mug/min increased FBF from 4.6+/-0.9 to 29.4+/-5.3 (539% increase) with dipyridamole/aspirin and from 3.9+/-0.8 to 12+/-2.5 mL/100 mL forearm/min (208% increase) with aspirin alone (P=0.007). In contrast, dipyridamole/aspirin did not alter the response to acetylcholine or to nitroprusside. The magnitude of adenosine-induced vasodilation correlated with plasma dipyridamole concentrations (r2=0.6); no correlation was observed with acetylcholine- or nitroprusside-induced vasodilation. Similar potentiation of adenosine, but not acetylcholine or nitroprusside, was observed in 7 additional subjects when adenosine, acetylcholine, and nitroprusside were given in random order before and 2 hours after a single dose of dipyridamole/aspirin. CONCLUSIONS: The effects of dipyridamole on resistance vessels are preferentially explained by potentiation of adenosine mechanisms rather than potentiation of nitric oxide or other cGMP-mediated actions.

Acetylcholine↗
PubMed1985

Effects of platelet-modifying drugs on arterial thromboembolism in baboons. Aspirin potentiates the antithrombotic actions of dipyridamole and sulfinpyrazone by mechanism(s) independent of platelet cyclooxygenase inhibition.

To resolve questions of drug actions, efficacy, and interactions for platelet-modifying agents used clinically, we have compared the relative capacities and mechanisms of aspirin, dipyridamole, sulfinpyrazone, and dazoxiben to prevent arterial thromboembolism in a baboon model. In 136 studies the agents were given twice daily by oral administration both singly and in combination. The antithrombotic efficacy of a given therapy was determined by its capacity to interrupt steady-state platelet utilization induced by thrombogenic arteriovenous cannulae. When given alone, dipyridamole and sulfinpyrazone reduced the rate at which platelets were utilized by thrombus formation in a dose-dependent manner with essentially complete interruption by dipyridamole at 10 mg/kg per d. In contrast, neither aspirin (2-100 mg/kg per d) nor dazoxiben (20-100 mg/kg per d) decreased cannula platelet consumption detectably despite the striking reduction in the capacity of platelets to produce thromboxane B2. However, aspirin, but not dazoxiben, potentiated the antithrombotic effects of dipyridamole and sulfinpyrazone in a dose-dependent fashion without changing the pharmacokinetics for any of the agents. Complete potentiation required aspirin at 20 mg/kg per d to be given with each dose of dipyridamole. Because dazoxiben's blockade of platelet thromboxane A2 production was not associated with antithrombotic potentiation, and because complete potentiation by aspirin required a dose that fully inhibited vascular production of prostaglandin I2 (PGI2), we conclude that aspirin's potentiating effect on dipyridamole is independent of PGI2 production or inhibition of thromboxane A2 formation. In addition, because frequent repeated and synchronous dosing of aspirin was necessary, aspirin's potentiating effects appear to be produced by mechanism(s) unrelated to its potent, irreversible inhibition of platelet cyclooxygenase.

Animals↗
PubMed1992

A comparison of tablets with oral suspension formulation of dipyridamole in thallium myocardial imaging.

Dipyridamole stress thallium imaging has been widely employed to diagnose and assess the extent of coronary heart disease in patients who cannot exercise. When oral dipyridamole administration was used, a wide range of results for sensitivity, specificity, hemodynamic response and side effect profile has been reported. The authors hypothesized that the formulation used for oral administration of dipyridamole plays a major factor in this variability, and that the pulverized form of dipyridamole will achieve faster and more consistent response than the standard tablet form. The authors studied 13 consecutive patients who underwent thallium scintigraphy. Eight patients received dipyridamole pulverized and dissolved in a glycol/aqueous base diluent (group A), and five patients received the standard form of dipyridamole (group B). In group A, mean peak systolic blood pressure decreased from 142 +/- 31 (mean +/- standard deviation) to 109 +/- 30 (P = .05), and mean diastolic blood pressure decreased from 76 +/- 14 to 51 +/- 5. The mean heart rate changed from 78 +/- 26 to 80 +/- 10. In group B, baseline systolic blood pressure was 165 +/- 12 and decreased to 156 +/- 7 at 45 minutes and to 155 +/- 14 at 90 minutes. Heart rate increased from baseline of 69 +/- 9 to 75 +/- 8 at 45 minutes and to 76 +/- 11 at 90 minutes. At 45 minutes, the systolic blood pressure of the 8 group A patients dropped by 33 +/- 19 mm Hg, whereas group B's changed by 9 +/- 6 mm Hg (P less than .005).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed2001

Head-to-head comparison of dipyridamole, dobutamine and pacing stress echocardiography for the detection of myocardial ischemia in an animal model of coronary artery stenosis.

To compare the sensitivity of dipyridamole, dobutamine and pacing stress echocardiography for the detection of myocardial ischemia we produced a physiologically significant stenosis in the left circumflex artery of 14 open-chest dogs (range: 50 to 89% reduction in luminal diameter). In each study, dobutamine (5 to 40 microg kg(-1) min(-1) in 3-min stages) and pacing (20 bpm increments, each 2 min, up to 260 bpm) were performed randomly, and then followed by dipyridamole (up to 0.84 mg/kg over 10 min). The positivity of stress echocardiography tests was quantitatively determined by a significant (P<0.05) reduction of or failure to increase absolute and percent systolic wall thickening in the stenotic artery supplied wall, as compared to the opposite wall (areas related to the left anterior descending artery). Systolic and diastolic frozen images were analyzed off-line by two blinded observers in the control and stress conditions. The results showed that 1) the sensitivity of dobutamine, dipyridamole and pacing stress tests was 57, 57 and 36%, respectively; 2) in animals with positive tests, the mean percent change of wall thickening in left ventricular ischemic segments was larger in the pacing (-19 +/- 11%) and dipyridamole (-18 +/- 16%) tests as compared to dobutamine (-9 +/- 6%) (P = 0.05), but a similar mean reduction of wall thickening was observed when this variable was normalized to a control left ventricular segment (area related to the left anterior descending artery) (pacing: -16 +/- 7%; dipyridamole: -25 +/- 16%; dobutamine: -26 +/- 10%; not significant), and 3) a significant correlation was observed between magnitude of coronary stenosis and left ventricular segmental dysfunction induced by ischemia in dogs submitted to positive stress tests. We conclude that the dobutamine and dipyridamole stress tests showed identical sensitivities for the detection of myocardial ischemia in this one-vessel disease animal model with a wide range of left circumflex artery stenosis. The pacing stress test was less sensitive, but the difference was not statistically significant. The magnitude of segmental left ventricular dysfunction induced by ischemia was similar in all stress tests evaluated.

Animals↗
PubMed1990

Effect of dipyridamole (Persantin) on blood flow and patency of aortocoronary vein bypass grafts.

The effect of dipyridamole was investigated in 360 patients undergoing coronary bypass surgery. They were randomly allocated to receive dipyridamole (100 mg orally q.i.d. for 2 days preoperatively, 5 mg/kg body weight/24 h i.v. peroperatively and 100 mg orally q.i.d. for 1 year postoperatively) or placebo. Withdrawn from the study were 48 patients on dipyridamole and 57 on placebo. Cardiovascular and/or cerebrovascular events or need for anticoagulant treatment were the reasons for withdrawal in 22 (13%) of the dipyridamole, and 34 (18%) of the placebo group. Logistic regression analysis of risk factors influencing graft patency showed significant relation to peroperatively measured coronary blood flow. A positive trend of treatment was observed (p = 0.08). Vein graft blood flow measured during bypass surgery (245 patients) was significantly greater in the dipyridamole group (p less than 0.01). The occlusion rate was lower in vessels with peroperative blood flow greater than 30 ml/min (vein-marginal p less than 0.01, vein-dexter p less than 0.05, vein-diagonal 0.05 less than p less than 0.1). Dipyridamole increases coronary blood flow and graft patency following coronary bypass surgery.

Aspirin↗
PubMedDate not supplied

Noninvasive prediction of restenosis after coronary angioplasty: a head to head comparison among exercise ECG, dipyridamole and exercise thallium scintigraphy.

Restenosis remains the main limitation of percutaneous transluminal coronary angioplasty (PTCA). Since it seems likely that restenosis not severe enough to induce ischemia may be better detected with pharmacological testing than with exercise, we investigated whether dipyridamole thallium scintigraphy is better than exercise-electrocardiogram and exercise-thallium in predicting restenosis after PTCA. Noninvasive tests and re-angiography were performed in 61 consecutive patients, 5-6 months after successful single vessel PTCA. Detection of vessel stenosis greater than or equal to 50% was used as angiographic criteria for restenosis. Exercise-induced angina, ST segment depression greater than or equal to 1 mm at exercise-electrocardiogram and reversible perfusion defects in the area supplied by the dilated vessel, during either dipyridamole and exercise-thallium, were considered noninvasive abnormal responses. The overall restenosis rate was 41% (25/61). Angina was the most specific (97%) of all criteria for restenosis, but also one of the least sensitive (40%), slightly better than exercise-ECG (24%). Exercise-thallium had lower sensitivity (72% vs 88%, p less than 0.05) and negative predictive value (82% vs 91%, p less than 0.05) than dipyridamole-thallium. In patients positive at both exercise-thallium and dipyridamole-thallium testing, mean stenosis at follow-up was more severe (73 +/- 23%) than in patients with positive dipyridamole-thallium and negative exercise-thallium (55 +/- 26%) results, but the difference did not reach statistically significant levels. For these reasons, dipyridamole-thallium seems to be an acceptable alternative to exercise thallium to follow patients after initially successful PTCA.

Aged↗
PubMed1999

[Therapy with nitro derivatives and the development of tolerance: a comparative study with stress ECG and dipyridamole ECG].

The ECG stress test represents the most commonly-used technique to evaluate the occurrence of nitroglycerin tolerance. It acts by increasing cardiac O2 demand with resulting insufficient blood flow through a stenotic coronary artery and development of cardiac ischemia. However, other tests are also potentially suitable, such as the ECG-dipyridamole test. The aim of the present study was to evaluate the acute response of ECG-dipyridamole and ECG-stress tests to nitroglycerin. In particular, the development of nitroglycerin tolerance during chronic therapy was evaluated with both tests in patients with stable angina. Eleven patients (8 men and 3 women) with CAD proven by a previous coronarography, a known history of stable angina within at least six months and a positive response to both the tests were studied. At the end of a seven-day wash-out period, all patients were positive to initial ECG-stress and ECG-dipyridamole tests; after 3 days a new evaluation was carried out (Effort 0 and Dip 0) and this confirmed the previous results. We performed a randomized trial in two phases: acute and chronic therapy. In the acute phase, all patients underwent ECG-stress and ECG-dipyridamole tests (Effort 1 and Dip 1) in a randomized fashion one day apart, four hours after administration of a 10 mg/24 h nitroglycerin patch. The chronic phase consisted of 25 days of continuous treatment with a nitroglycerin patch. The two tests (Effort 2 and Dip 2) were always repeated after four hours of the morning therapy. Nitroglycerin does not modify the hemodynamic response to dipirydamole in either acute or chronic treatment. Lastly, our data confirm the efficacy of nitroglycerin on stress and dipyridamole tests after acute administration. Nitroglycerin tolerance is confirmed by both tests although with different patterns. ECG stress test showed nitroglycerin tolerance because time to ischemia and max ST deteriorated during chronic therapy. Moreover, the ECG-dipyridamole test showed nitroglycerin tolerance because five patients with a negative acute test (Dip 1) became positive during chronic therapy (Dip 2).

Administration, Cutaneous↗
PubMed2000

[The echo-stress test with dipyridamole-atropine on the 3rd-5th day of an uncomplicated acute myocardial infarct for risk stratification and early discharge].

BACKGROUND: The aim of this study was to evaluate if dipyridamole-atropine stress echocardiography (DASE) performed between the third-fifth day in uncomplicated acute myocardial infarction allows for an effective risk stratification with an early discharge in some cases. METHODS: Between February 1997 and September 1998, 190 patients (138 males and 52 females, mean age 59 +/- 10.3 years), with acute myocardial infarction, were enrolled in the study. DASE was performed between the third-fifth day with a dipyridamole infusion of 0.84 mg/kg over 10 min followed by 1 mg of atropine from the twelfth to the fifteenth minute. DASE was considered positive in the presence of a new or worsening dyssynergy. Patients with heart failure, angina, major arrhythmias, and poor acoustic window were excluded. In the follow-up spontaneous events were defined as cardiac death, non-fatal myocardial reinfarction, unstable angina or heart failure (with hospitalization). RESULTS: DASE was performed in 92 patients (48.4%), all without complications: 29 patients (31.5%) had a negative DASE result, and 63 patients (68.5%) had a positive DASE. The average hospital stay of patients with a negative test was significantly lower in comparison with that of patients with a positive test (7.55 +/- 1.32 vs 9.29 +/- 1.61 days, p < 0.0001). Events occurred in 19 patients (20.6%), 2/29 patients with a negative DASE (6.9%), 17/63 patients with a positive DASE (27%), 6/43 patients with homozonal positivity after atropine or high-dose dipyridamole (14%), 11/20 patients with heterozonal positivity or homozonal positivity after low-dose dipyridamole (55%). On univariate analysis the variables significantly associated with spontaneous events were: age (chi 2 = 6.41, p = 0.019), left ventricular ejection fraction at rest (chi 2 = 8.89, p = 0.004), number of asynergic segments after stress (chi 2 = 6.87, p = 0.010), increase in the number of asynergic segments after stress (chi 2 = 4.01, p = 0.039), wall motion score index after stress (chi 2 = 9.60, p = 0.003), increase in wall motion score index after stress (chi 2 = 3.60, p = 0.049), DASE positivity (chi 2 = 4.89, p = 0.029), homozonal positivity after low-dose dipyridamole (chi 2 = 8.57, p = 0.013), heterozonal positivity (chi 2 = 13.10, p = 0.001). On Cox's multivariate analysis independent predictors of events were: age (relative risk 3.92, p = 0.0146), DASE positivity (relative risk 1.79, p = 0.0054). CONCLUSIONS: DASE between the third-fifth day in uncomplicated acute myocardial infarction is feasible, tolerable, safe, and effective for early risk stratification. A negative DASE detects a "very low-risk" patient group, and allows for an earlier hospital discharge, without an increased risk of events. The heterozonal positivity or the homozonal positivity after low-dose dipyridamole indicates the need for a coronarography, due to the high risk of events at follow-up.

Aged↗
PubMed1975

Dipyridamole and thrombocyte count in open-heart surgery.

The effect of dipyridamole (Persantine) on the thrombocyte count in connection with open-heart surgery and perfusion was studied in 12 patients. A control series of 38 patients undergoing open-heart surgery was available. The dose of dipyridamole, depending on the duration of the perfusion, was 40 to 80 mg. intravenously. We found that dipyridamole definitely had the effect of maintaining the thrombocyte count. At the end of perfusion, the mean thrombocyte count in the dipyridamole group was 129 +/- 20.6 x 10(9)/L. and in the control group 82 +/- 7.4 x 10(9)/L. The result was statistically almost significant (p less than 0.05). At the end of anesthesia the respective mean values were 164.9 +/- 29.7 and 110.8 +/- 8.1 x 10(9)/L. The difference was almost significant (p less than 0.05). The use of dipyridamole did not increase the postoperative hemorrhagic tendency. Our results support the earlier experimental findings that dipyridamole favors the maintenance of thrombocyte counts.

Adult↗
PubMed2002

Adverse reactions to dipyridamole in patients undergoing stress/rest cardiac perfusion testing.

OBJECTIVE: A reaction scale was used to assess noncardiac adverse reactions exhibited by nuclear medicine outpatients receiving intravenous dipyridamole for pharmacological stress testing. METHODS: The study included 933 patients referred to 2 cardiac outpatient centers for assessment. All patients evaluated in this study were unable to perform treadmill stress testing and underwent pharmacological intravenous dipyridamole stress testing. Dual-isotope (201)Tl rest/(99m)Tc-sestamibi stress imaging was performed. An analysis of adverse reactions exhibited by patients given dipyridamole was tabulated. RESULTS: Of the 933 patients, 520 (55.7%) demonstrated no adverse reaction to intravenous dipyridamole; 413 patients (44.3%) had adverse reactions of some type. Many of these patients had multiple types of reactions, and a total of 604 reactions were recorded. The most prevalent adverse reaction was headache (224 reactions; 37.1%), followed by chest pain (73 reactions; 12.1%), and nausea (67 reactions; 11.1%). A sex comparison revealed 271 of 454 male patients (59.7%) and 249 of 479 female patients (52%) demonstrated no adverse reaction to intravenous dipyridamole. An evaluation of the most prevalent adverse reaction (headache) demonstrated a significant difference between males (37.9%) and females (62.1%). CONCLUSION: An adverse reaction scale characterizing common noncardiac side effects of dipyridamole in nuclear medicine cardiac patients demonstrated the most prevalent adverse reaction was headache. Analysis by sex revealed that significantly more females than males complained of headaches.

Chest Pain↗