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Correlation of diagnostic accuracy of dipyridamole thallium-201 myocardial scintigraphy and clinical findings during stress.

The relationship between dipyridamole thallium-201 myocardial single-photon emission computed tomography and clinical findings during stress testing was investigated in 57 patients (mean age 72 years), including 11 patients with normal coronary arteries. Systolic blood pressure decreased from 138.2 +/- 19.7 to 119.8 +/- 20.1 mmHg (mean: -13.8 +/- 6.6%) after dipyridamole infusion (0.568 mg/kg/4 min). Scintigraphic sensitivity for the diagnosis of coronary artery disease was higher in 30 patients with a systolic blood pressure decrease above the average value than in 27 patients with a blood pressure reduction of less than 14% (88% vs. 60%, p < 0.005). Reversible perfusion defects among stenosed coronary arteries were more frequent in the former group (73% vs. 27%, p < 0.001) with no difference in other clinical findings. In conclusion, systolic blood pressure change during stress testing was significantly correlated with dipyridamole-induced perfusion defects and detectability of coronary stenosis.

Aged↗

Myocardial viability in cases with persistent perfusion defects on the dipyridamole thallium-201 scintigram. A comparative study with autopsy findings.

The aim of this study was to assess the incidence of myocardial infarction among persistent perfusion defects in dipyridamole-stress thallium scintigraphy by inspecting autopsied hearts and to evaluate whether the regional thallium activity of a scintigraphic defect can predict the presence of infarction. Autopsied hearts were compared with dipyridamole myocardial scintigrams undertaken during life in 27 patients (mean age 85 +/- 8 years). The time interval from stress testing until death was 428 +/- 351 days. Regional thallium uptake of delayed perfusion defect was calculated on the short axis images. The grade of regional myocardial fibrosis in autopsy specimens was also quantified to correlate with the corresponding regional thallium uptake. In 6 of 15 (40%) regions with persistent defects on the scintigram, myocardial infarction was not found at autopsy. Regional thallium-201 uptake of delayed defects < 50% diagnosed infarction with a sensitivity of 82% and a specificity of 80%. A linear correlation (r = -0.67) was observed between percent thallium-201 uptake and the degree of myocardial fibrosis. In conclusion, perfusion defects at 4-hour imaging in dipyridamole-stress testing may overestimate the presence of myocardial infarction and regional thallium-201 activity is helpful in distinguishing between defects with and without infarction.

Aged↗

Whole-heart dipyridamole stress first-pass myocardial perfusion MRI for the detection of coronary artery disease.

A whole-heart coverage MRI sequence, which employes a hybrid of fast gradient echo and echo planar acquisition imaging (FastCard EchoTrain), has recently been developed. Using this sequence, a first-pass myocardial perfusion MRI was shown to be a good noninvasive modality for detecting coronary artery disease (CAD) in a clinical setting. In addition, the clinical usefulness of delayed enhanced MRI has recently been reported. The objectives of this study were (1) to investigate the accuracy of dipyridamole stress first-pass myocardial perfusion MRI for diagnosing CAD (> 50% stenosis) and (2) to clarify whether additional delayed enhancement MRI has any clinical significance. We performed first-pass myocardial perfusion MRI in 102 consecutive patients (66 +/- 9 years old) suspected to have CAD or new lesions in patients with well-documented prior myocardial infarction (MI). Using a 1.5 T cardiac MR imager (GE CV/i), eight short axis MR images of the left ventricle were acquired by injecting gadolinium (0.1 mmol/kg) under dipyridamole infusion stress (0.56 mg/kg). Fifteen minutes later, aminophylline (250 mg) was injected and first-pass perfusion MRI was repeated in the resting state in order to evaluate both the presence of perfusion defect and delayed enhancement. The presence of perfusion defect and delayed enhancement was determined based on a visual qualitative analysis by the agreement of two separate readers who were blinded to any clinical information. Based on the stress and rest findings, no defect, reversible defect, or fixed defect with or without delayed enhancement was recorded in any patient. The MR findings revealed 76 CAD patients, including 24 MI patients with new lesions and 26 patients without CAD on coronary angiography. The presence of stress perfusion defect had a 93% sensitivity and an 85% specificity for diagnosing CAD. A fixed defect showed an 86% sensitivity and a 66% specificity for diagnosing a prior MI. Patients with a fixed defect with delayed enhancement had more significant stenosis in the infarct related artery than in those without any enhancement (11/26 vs 15/20, P < 0.05). Dipyridamole stress first-pass myocardial perfusion MRI using the FastCard EchoTrain was found to be a clinically useful and accurate modality for diagnosing CAD.

Aged↗

Dipyridamole electrocardiography test for the detection of severe coronary artery stenoses.

To investigate the relationship between dipyridamole-induced ST depression and the severity of coronary artery stenosis, the dipyridamole injection test (D) at 0.568 mg/kg/4 min, and the symptom limited treadmill exercise test (T) were performed separately in 16 normal volunteers and 167 patients who underwent coronary arteriography [91 patients without myocardial infarction (non-MI group) and 76 patients with previous myocardial infarction (MI group)]. Standard 12-lead electrocardiogram and body surface mapping of 87 leads were recorded in both tests. None of the normal volunteers had significant ST depression (greater than or equal to 0.10 mV) in D or T. Regarding the non-MI group, D had as high an incidence of ST depression as T (83% vs 93%) in patients with maximal coronary stenosis greater than or equal to 90%, while in those with maximum coronary stenosis less than 90%, D had a lower incidence of ST depression than T (16% vs 48%, p less than 0.01). For the MI group, the incidence of ST depression was compared to the maximal coronary artery stenosis supplying the non-infarcted area. In patients with maximal coronary artery stenosis greater than or equal to 90%, D had as high an incidence of ST depression as T (71% vs 64%). While, D had a lower incidence of ST depression than T (19% vs 35%, p less than 0.05) in those with maximum coronary artery stenosis less than 90%. For the diagnosis of coronary artery stenosis of greater than or equal to 90%, D had as high sensitivity (non-MI group, 82% vs 93%; MI group, 71% vs 64%) and higher specificity (non-MI group, 84% vs 52%, p less than 0.01; MI group, 81% vs 65%, p less than 0.05) compared with T. This study demonstrated that dipyridamole ECG is a sensitive and specific test to detect severe coronary artery stenosis.

Adult↗

Myocardial rest iodine-123-beta-methyl-iodophenyl-pentadecanoic acid scintigraphy compared with dipyridamole stress thallium-201 scintigraphy in unstable angina.

Twelve patients with stable angina and 12 patients with unstable angina underwent rest iodine-123-beta-methyl-iodophenyl-pentadecanoic acid (BMIPP), dipyridamole stress thallium scintigraphy and delayed thallium scintigraphy. In stable angina, sensitivity for detecting ischemic segments was higher in dipyridamole thallium (74%) than rest BMIPP (48%) images (p<0.05), but there was no significant difference between the 2 images in unstable angina. In unstable angina, the incidence of segments with higher defect scores on BMIPP images than on delayed thallium images and the opposite pattern was 27 and 5 (p<0.01). In stable angina, there was no difference. The mean defect score on BMIPP (6.3 +/- 5.6) was higher than that on delayed thallium scintigraphy (2.9 +/- 2.7) and it was almost the same as on the initial dipyridamole stress test (6.5 +/- 5.2). In conclusion, BMIPP scintigraphy is safer and may be as useful in detecting myocardial ischemia in patients with unstable angina as thallium scintigraphy.

Angina Pectoris↗

Platelet adhesion studies on dipyridamole coated polyurethane surfaces.

Surface modification of polyurethanes (PUs) by covalent attachment of dipyridamole (Persantin) is known to reduce adherence of blood platelets upon exposure to human platelet rich plasma (PRP). This effect was investigated in further detail. First platelet adhesion under static conditions was studied with four different biomaterial surfaces: untreated PU, PU immobilised with conjugate molecule 1, PU immobilised with conjugate molecule 2, and PU immobilised with conjugate molecule 3. In PU immobilised with 1 dipyridamole is directly linked to the surface, in PU immobilised with 2 there is a short hydrophilic spacer chain in between the surface and the dipyridamole, while conjugate molecule 3 is merely the spacer chain. Scanning electron microscopy (SEM) was used to characterise platelet adhesion from human PRP under static conditions, and fluorescence imaging microscopy was used to study platelet adhesion from whole blood under flow. SEM experiments encompassed both density measurements and analysis of the morphology of adherent platelets. In the static experiments the surface immobilised with 2 showed the lowest platelet adherence. No difference between the three modified surfaces emerged from the flow experiments. The surfaces were also incubated with washed blood platelets and labeled with Oregon-Green Annexin V. No capture of Oregon-Green Annexin V was seen, implying that the adhered platelets did not expose any phosphatidyl serine at their exterior surface.

Adult↗

Routine perioperative dipyridamole 201Tl imaging in diabetic patients undergoing vascular surgery.

OBJECTIVE: To assess the utility of dipyridamole thallium testing in symptomatic and asymptomatic patients with diabetes undergoing vascular surgery. RESEARCH DESIGN AND METHODS: Dipyridamole 201Tl myocardial scintigraphy was performed preoperatively in 93 consecutive patients with diabetes undergoing peripheral vascular procedures. The utility of clinical and thallium variables in predicting cardiovascular complications was assessed. RESULTS: Two groups of patients were identified: group A (36 patients) without clinical evidence of cardiac disease and group B (57 patients) with clinical evidence of cardiac disease. Dipyridamole thallium scans were abnormal in 21 of 36 (58%) of group A patients compared with 53 of 57 (93%) of group B patients (P < 0.0001). Compared with group B patients with perfusion defects, group A patients with perfusion abnormalities tended to have fewer defects per scan (2.7 +/- 1.5 vs. 3.6 +/- 1.9, P = 0.05). No perioperative cardiac complications occurred in group A patients while perioperative cardiac complications occurred in 9 of 57 (16%, 95% CI 7-28%) group B patients (P = 0.01). For the entire study population, the complication rate was 10%. CONCLUSIONS: Diabetic individuals without clinical markers for coronary artery disease appear to be at low risk for adverse postoperative cardiac events after vascular surgery. Preoperative myocardial perfusion imaging may add little to cardiovascular risk assessment in this subgroup of patients with diabetes.

Aged↗

Dipyridamole affects myocardial adenosine kinase activity.

Adenosine kinase (EN 2.7.1.20) from rat and dog heart was purified until it was devoid of adenosine deaminase activity. A stimulation of adenosine kinase activity by dipyridamole was observed when the enzyme was assayed under optimal conditions. At low substrate concentrations adenosine kinase was inhibited by the drug. It increased the Km for adenosine sevenfold. The effects of dipyridamole were Mg2+-dependent. The adenosine-sparing action of dipyridamole at low substrate concentrations is in keeping with the vasodilatory action of the drug.

Adenosine Kinase↗

[The safety and diagnostic accuracy of dipyridamole-loading myocardial tomography with thallium-201 in the elderly with coronary artery disease].

To test the diagnostic accuracy and safety of dipyridamole-loading myocardial imaging with thallium-201 (T1) in the elderly, we performed myocardial tomography in 42 patients with coronary artery disease (CAD). While monitoring of ECG and blood pressure, dipyridamole was infused at a rate of 0.57 mg/kg body weight over 4 minutes, and 4 minutes later T1 (3 mCi) was injected. Five minutes later (initial) and 3 hours after T1 injection (redistribution) myocardial images were obtained from 32 projections by a rotating gamma camera. After low-pass filtering, images were reconstructed into short-axis, horizontal long-axis and vertical long-axis tomograms. Myocardial T1 distribution both on initial and redistribution images and myocardial T1 washout rate's (WOR) of the entire left ventricle were expressed into two-dimensional polar maps by using short-axis cuts (bull's-eye maps). In addition to visual interpretation, abnormal WOR (less than 18%) was used as a criteria of dipyridamole induced myocardial ischemia. Patients were divided into 2 groups. Group I consisted of 24 patients more than 70 years of age and Group II consisted of 18 patients less than 65 years of age. The clinical and coronary angiographic characteristics of the two groups did not differ. The sensitivity of this method for the detection of CAD was identical (83%) between the 2 groups, and the detection of coronary artery stenosis was 73% in Group I and 74% in Group II (NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

[Usefulness of dipyridamole thallium scintigraphy in the diagnosis of coronary artery disease in elderly patients].

Patients suspected of having coronary artery disease (CAD) underwent dipyridamole thallium scintigraphy, exercise electrocardiography, and coronary angiography. Of the 500 patients studied, 163 were at least 65 years old, and 337 were less than 65 years old. Both CAD and multivessel CAD were more common in elderly than in younger patients (81% vs 69%, p < 0.01 for CAD; and 43% vs 26% p < 0.01 for multivessel CAD). In patients without myocardial infarction, the specificity of exercise electrocardiography was lower among elderly patients than among younger patients (52% vs 61%), but the sensitivity was higher (87% vs 75%). In contrast, both the sensitivity and the specificity of dipyridamole thallium scintigraphy were similar in the two age groups (86% vs 87% and 79% vs 74%). Among patients with myocardial infarction and a positive exercise test, reversible defects were equally common in the two age groups (60% vs 58%). The reversible defects were in areas remote from the area of infarction in half of the patients in both groups. Among patients with negative exercise-test results, reversible defects were more common in elderly patients than in younger patients (57% vs 38%). The reversible defects were in the infarcted area in 71% and 79% of these patients, respectively. These results indicate that dipyridamole thallium scintigraphy is a sensitive and specific method for detecting CAD, independent of age. It is particularly useful in identifying myocardial viability in the infarcted area.

Adult↗

[Assessment of exercise-induced silent myocardial ischemia by dipyridamole thallium imaging. (2). Its significance in Q wave myocardial infarction].

The clinical significance of silent myocardial ischemia (SMI) in the elderly was assessed in 91 patients with Q wave infarction who showed ischemic ST depression during treadmill stress testing, as well as reversible defect (RD) during dipyridamole thallium imaging. They were divided into two groups (47 patients with silent ST depression and 44 patients with painful ST depression) and compared for scintigraphic and coronary arteriographic features, and prognosis. There was no significant difference in age, gender and site of infarction between the two groups. The prevalence of single and double vessel coronary stenosis was higher in patients with SMI (66%) than in those with painful ischemia (p < 0.05). The results of treadmill stress testing showed a longer exercise duration (4.7 +/- 1.7 vs. 4.1 +/- 1.8 min) and higher maximal heart rate (138 +/- 15/vs. 126 +/- 20/min) in patients with SMI than in those with painful ischemia (p < 0.01). Dipyridamole thallium imaging revealed a larger infact (18.8 +/- 9.1 vs. 14.6 +/- 10.2 segments) in patients with SMI than in those with painful ischemia (p < 0.05). The prevalence of RD in the area of infarction was also higher in patients with SMI (74%) than in those with painful ischemia (45%) (p < 0.05). Although a higher proportion of the patients with painful ischemia (42%) underwent CABG or PTCA as their initial therapy, compared with those with SMI (25%) (ns), there was no difference in the cardiac event rate between the two groups who were initially treated medically. Dipyridamole thallium imaging is useful in the assessment of SMI in elderly patients with Q wave myocardial infarction. Those with SMI may have a larger infarct and a higher prevalence of ischemia localized within the infarction than those with painful ischemia.

Aged↗

Inhibition by dipyridamole of cerebral vasospasm induced in vitro by whole blood.

This study evaluates the effect of dipyridamole, an inhibitor of platelet aggregation, on cerebral artery contraction induced in vitro by the addition of whole blood. Whole fresh arterial blood added to isolated rabbit basilar artery bathed in a physiological buffer produces a sustained contraction in vessels observed for 60 minutes. Significant dose-dependent inhibition of contraction was observed when dipyridamole was added to the vessel bath. This effect was not influenced by preincubating cerebral vessels with aspirin, an inhibitor of prostaglandin synthesis. It is suggested that inhibition of whole blood-induced cerebral artery contraction by dipyridamole does not result from potentiation of cerebral vessel prostaglandin pathways, but possibly from a direct effect on platelets.

Animals↗

Effect of fluvastatin and dipyridamole on proteinuria and renal function in childhood IgA nephropathy with mild histological findings and moderate proteinuria.

AIM: In recent reports, some kinds of HMG-CoA reductase inhibitors were able to decrease proteinuria and to improve renal function. Here we aimed to clarify the effect of fluvastatin (an HMG-CoA reductase inhibitor) on proteinuria and renal function in children with mild IgA nephropathy. PATIENTS AND METHODS: We conducted a prospective controlled study of 30 children who had been recently diagnosed with normocholesterolemic IgA nephropathy following the detection of a minor lesion or of focal mesangial proliferation and moderate proteinuria. The 30 patients were randomly assigned to receive both of 20 mg of fluvastatin and 5 mg/kg of dipyridamole (group 1), or 5 mg/kg of dipyridamole only (group 2) for 1 year. RESULTS: By the end of the trial, urinary protein, hematuria, BUN and serum creatinine levels had significantly decreased in the patients of group 1 as compared to baseline. Serum total cholesterol, triglyceride and LDL cholesterol levels had significantly decreased, while serum total protein and albumin, and creatinine clearance had significantly increased in group 1 as compared to baseline and group 2. The urinary protein level had significantly decreased in the group 2 patients as compared to baseline, but only slightly. CONCLUSIONS: The results of this study suggest that fluvastatin and dipyridamole treatment yields an antiproteinuric effect and leads to the amelioration of renal function in moderately proteinuric patients with mild histological IgA nephropathy.

Adolescent↗

Failure of aspirin plus dipyridamole to prevent restenosis after carotid endarterectomy.

OBJECTIVE: To evaluate therapy with aspirin plus dipyridamole in reducing restenosis after carotid endarterectomy. PATIENTS: A total of 163 patients having 175 surgical carotid endarterectomies. INTERVENTION: Eighty-three patients (90 endarterectomies) were randomly assigned to receive oral aspirin, 325 mg, plus dipyridamole, 75 mg, beginning 12 hours preoperatively, followed by a second dose administered within 8 hours after the operation, and given three times daily thereafter for 1 year. Eighty patients (85 endarterectomies) received placebo medication that was identical in appearance to the study drugs. MEASUREMENTS: After the adequacy of the surgical procedure was confirmed by intraoperative angiography, restenosis at the endarterectomy sites was evaluated using serial duplex ultrasound studies before hospital discharge and at 3-month intervals postoperatively for 1 year. RESULTS: Based on the time for developing identifiable restenosis and on efficacy analysis, greater than 50% restenosis developed in 11 operated vessels (16%) in the treated group and in 10 arteries (14%) in the placebo group, yielding an observed risk increase of 14% (95% CI, -52% to 167%; P greater than 0.2). By intention-to-treat analysis, greater than 50% restenosis developed in 16 of 90 operated vessels in treated patients and in 10 of 85 arteries in patients receiving placebo (26% for the treated group and 12% for the placebo group; P = 0.18, Mantel-Haenszel statistic), representing an observed risk increase of 110% (CI, -5% to 365%). Similar differences were observed for greater than 20% restenosis and for the comparison of patients rather than operated vessels by either intention-to-treat or efficacy analyses. CONCLUSIONS: Because therapy not only failed to reduce carotid restenosis but may have actually increased its frequency, treatment with aspirin plus dipyridamole probably has no clinically important benefit on restenosis in patients having carotid endarterectomy.

Aged↗

Ineffectiveness of aspirin and dipyridamole in the treatment of thrombotic thrombocytopenic purpura.

Platelet-inhibiting drugs have been used widely in the treatment of thrombotic thrombocytopenia purpura. Nineteen consecutive patients received various treatments including platelet inhibitors, glucocorticoid drugs, whole blood or plasma exchange transfusions, and splenectomy. During treatment with aspirin and dipyridamole in 14 patients, five died, and only one had neither new neurologic signs nor worsening thrombocytopenia. Prostacyclin in one patient was not beneficial. Serious bleeding complications, including massive upper gastrointestinal hemorrhage, epistaxes, or subarachnoid hemorrhage confirmed at autopsy, occurred in five of the 19 patients and only during treatment with aspirin and dipyridamole. We conclude that there is no evidence for the effectiveness of aspirin and dipyridamole in the treatment of thrombotic thrombocytopenic purpura and that these drugs may increase the risk of serious bleeding complications.

Adolescent↗

Inhibition of human and animal platelet adhesiveness to glass bead columns by adenosine, dipyridamole, chlorpromazine and acetylsalicylic acid.

The differences among human, rabbit and guinea-pig platelet adhesiveness as for inhibitions by adenosine, dipyridamole, chlorpromazine and acetylsalicylic acid are described, and the influence of measurement conditions on platelet adhesiveness is also reported. Platelet adhesiveness of human and animal species decreased with an increase of heparin concentrations and an increase of flow rate of blood passing through a glass bead column. Human and rabbit platelet adhesiveness was inhibited in vitro by adenosine, dipyridamole and chlorpromazine, but not by acetylsalicylic acid. On the other hand, guinea-pig platelet adhesiveness was inhibited by the four drugs including acetylsalicylic acid. In in vivo study, adenosine, dipyridamole and chlorpromazine inhibited platelet adhesiveness in rabbits and guinea-pigs. Acetylsalicylic acid showed the inhibitory effect in guinea-pigs, but not in rabbits.

Adenosine↗

Regional distribution and timing of wall motion abnormalities during echo-dipyridamole stress test in patients with stable angina: the elusive link between coronary stenoses and myocardial ischemia.

BACKGROUND: Classic experimental studies have shown that in the presence of a flow-limiting coronary artery stenosis, myocardial ischemia during metabolic or pharmacological arteriolar vasodilation causes wall motion abnormalities, which precede electrocardiographic (ECG) changes in the myocardial regions supplied by the stenotic branch. The aim of this study was to establish whether in patients with chronic stable angina the regional distribution of wall motion changes and sequence of ischemic events are similar to that observed in experimental models, as currently believed. METHODS: The study population consisted of 20 men and 4 women (mean age 59 +/- 10 years) who were recruited on the basis of the following criteria: 1) a history of chronic stable angina without clinical and instrumental evidence of previous myocardial infarction; 2) reproducible positive exercise tests for ECG myocardial ischemia and anginal pain; 3) angiographically normal left ventricular function; 4) isolated stenosis of the left anterior descending coronary artery (LAD). Patients underwent continuous 12-lead ECG and echocardiographic monitoring during dipyridamole infusion. RESULTS: During dipyridamole infusion 3 patients (13%) did not develop echocardiographic changes, ECG changes or angina, 14 (58%) exhibited ECG changes, 18 (75%) lamented angina and 16 (67%) developed echocardiographic changes. In 5 of these 16 patients (31.5%) echocardiographic changes occurred in LAD-dependent territories only, in 5 they occurred in non-LAD-dependent territories only (31.5%) and in 6 (37%) they occurred in both LAD- and non-LAD-dependent territories. A total of 14 patients exhibited both echocardiographic and ECG changes and/or angina. In 6 of these 14 patients (43%) echocardiographic changes were the first ischemic events; in the remaining 8 patients (57%) ECG changes and/or angina were the first ischemic events. CONCLUSION: In the majority of patients during dipyridamole infusion regional wall motion changes occur in territories supplied by non-stenotic coronary artery branches; they are probably caused, therefore, by distal vessel dysfunction. Furthermore, the sequence of ischemic events is different in individual patients. These findings indicate that in stable angina the mechanisms of ischemia are multiple and that the link between coronary stenoses and myocardial ischemia is very elusive.

Adult↗

Evidence of walk-through phenomenon during echocardiographic dipyridamole stress test.

This case report deals with induced regional wall motion abnormalities that spontaneously disappeared during an echocardiographic stress test with dipyridamole. A patient underwent this test because of atypical chest discomfort and a positive result of exercise stress test. Transient septal, apical and anterior akinesia were observed after the first dose of dipyridamole, but they were short-lasting and did not return during the continuation of the test. Coronary angiography showed a critical stenosis of the left coronary artery. A mechanism similar to that responsible for the walk-through phenomenon might explain the observed findings. Thus stress echo with dipyridamole needs careful continuous monitoring, because transient wall motion abnormalities can otherwise be missed resulting in a false negative test.

Coronary Angiography↗