Dipyridamole-echocardiography test in effort angina pectoris

This study assesses the clinical feasibility and usefulness of dipyridamole infusion for the detection of coronary artery disease (CAD) by using 2-dimensional echocardiography (2-D echo) and 12-lead electrocardiographic monitoring. Dipyridamole infusion (0.14 mg/kg/min for 4 minutes) was performed in 66 consecutive patients with effort chest pain and in 9 control subjects. Among the 28 patients with positive dipyridamole-echocardiography test responses, 18 had diagnostic electrocardiographic changes (ST-segment depression on anterolateral leads), but these changes were unrelated to the site of asynergy. The dipyridamole-echocardiography test had an overall sensitivity of 56% and specificity of 100% for the presence of CAD. Exercise stress testing (EST) had an overall sensitivity of 62% and a specificity of 80%. Thus, the dipyridamole-echocardiography test, which is feasible in essentially all patients with good basal echocardiograms, has a lower overall sensitivity in detecting CAD than EST but a higher specificity, detects the site of apparent ischemia as identified by regional asynergy more precisely than EST, and can unmask electrocardiographically silent effort ischemia.     

Random exercise stress test in diagnosing effort angina

To improve the performance of exercise stress testing in the diagnosis of effort angina while minimizing risks of serious complications, we evaluated an impulse response of ST changes, which is a transient ST response resulting from a hypothetical, strenuous-impulselike exercise, without actually imposing the strenuous load. To obtain the impulse response, subjects walked intermittently according to a computer-generated random binary sequence on a treadmill for 20 minutes (with a constant speed of 1.7 mph and a slope of 10%). We used Fourier transform for beat-to-beat changes in ST level and the binary sequence of exercise. We then determined the transfer function by taking the ratio of Fourier transformed ST level to exercise over the frequency range of 0.5 through 5.0 cycles/min. Converting the transfer function to the time domain yielded the impulse response of ST change. The subjects consisted of 49 patients (60 +/- 9 years) with effort angina, 13 patients with atypical chest pain (56 +/- 9 years), and 30 healthy, male volunteers (23 +/- 7 years). In 82 subjects (89%), the ST impulse response showed an initial depression followed by a smooth, gradual restoration toward the preexercise ST level (type I response). The average duration of the initial depression was 8 +/- 3 seconds in the healthy volunteers, whereas it was significantly prolonged to 23 +/- 14 seconds in effort angina (p less than 0.05). The depression in patients with atypical chest pain was not significantly different from that in the healthy volunteers.(ABSTRACT TRUNCATED AT 250 WORDS)     

Sir James Paget (1814-1894)

Sir James Paget (Fig. 1) formed with William Fergusson (1808–1862)and Sir Benjamin Brodie (1783–1762) a triumvirate of surgical‘greats' in England in the nineteenth century [1]. Pagetwas born in Great Yarmouth, Norfolk, England, and until 20 yrof age had not ventured further than a few miles from his birthplace.His father, Samuel, was a prosperous businessman who unfortunatelywent bankrupt, so that James after his elementary school educationin Great     

Diagnostic value of the isoproterenol test in effort tachycardia

An isoproterenol test was performed in 69 patients during electrophysiological investigation to assess its diagnostic value in adrenergic supraventricular or ventricular tachycardia. Sixteen control subjects had no symptoms on exercise and routine exercise stress testing did not trigger any hyperexcitability. Sixteen patients had reproducible documented supraventricular tachycardia induced by exercise (13 paroxysmal junctional tachycardias, 3 focal atrial tachycardias). Eight patients had ventricular hyperexcitability related to effort. Twenty-nine patients had supraventricular and/or ventricular hyperexcitability only at rest. Electrophysiological investigations included paired atrial stimulation during sinus rhythm and paced rhythm followed by programmed ventricular stimulation using one and then two extrastimuli delivered during sinus rhythm and paced ventricular rhythm. These stimulation studies were carried out under basal conditions and then during low dose isoproterenol infusion (10 to 40 micrograms) which accelerated the heart rate to 130/mn. Electrophysiological and conduction parameters and the mode of induction of the tachycardia (defined as at least 5 successive echos with a configuration similar to the clinical tachycardia) were studied. We observed an acceleration of anterograde and retrograde conduction and a shortening of the effective atrial and ventricular refractory periods but these changes were found equally in the different groups of patients and were not related to the induction of tachycardias. The induction of paroxysmal junctional tachycardia by isoproterenol was a very sensitive (92%) and specific (100%) diagnostic method. Its diagnostic value was much greater than Holter monitoring (25%) and exercise stress testing (12.5%). Induction of ventricular tachycardia by isoproterenol was also very sensitive (75%) and specific (95%). The diagnostic value was higher than exercise stress testing (71%) and Holter monitoring (62%). Isoproterenol did not affect the induction of spontaneous tachyarrythmias unrelated to effort and even suppressed the triggering of some episodes. In conclusion, the induction by atrial or ventricular pacing or spontaneous supraventricular or ventricular tachycardia during isoproterenol infusion was very specific and correlated with the concept of tachycardia induced by exercise and therefore of adrenergic nature. The sensitivity of this test was excellent in patients with supraventricular tachycardia (95%) and very good in ventricular tachycardia (75%). On the other hand, the changes in the electrophysiological parameters were not specific for a group of patients.     

Evaluation of an over-the-counter glycated hemoglobin (A1C) test kit

Background

Glycated hemoglobin (A1C) monitoring is an integral component of diabetes management. This study was conducted to evaluate the performance of the A1CNow^® SELFCHECK device when used by lay users and health care professionals (HCPs) to measure A1C.

Methods

Subjects performed two A1CNow SELFCHECK finger-stick self-tests followed by a finger-stick test of the subject’s blood by a HCP. The primary endpoint assessed accuracy of the subject and HCP A1CNow SELFCHECK readings. Secondary endpoints included precision, comprehension of instructional material (written material ± DVD), and product satisfaction. For accuracy comparison, a venous blood sample was drawn from each subject and tested by laboratory (TOSOH) analysis. Subject comprehension of product instructional material was evaluated via first-time failure (FTF) rate as recorded by the HCP, and subject satisfaction was assessed through written survey.

Results

A total of 110 subjects with (n = 93) and without (n = 17) diabetes participated. Of 177 subject A1C values, 165 (93.2%) were within the acceptable range of ±13.5% of the laboratory reference value and considered accurate. Regression analysis showed good correlation of subject values to laboratory and HCP results (R² = 0.93 for both). The average within-subject coefficient of variation was 4.57% (n = 74). The FTF rates with and without instructional DVD were 11.3% (n = 56) and 39.6% (n = 54), respectively. Subjects with diabetes/prediabetes overwhelmingly indicated that they were “very” to “extremely” likely (93.5%) to discuss their home A1C results with their HCP.

Conclusions

Lay users found the A1CNow SELFCHECK easy to use, and both lay users and HCPs were able to measure A1C accurately.     

High dose dipyridamole echocardiography test in effort angina pectoris

The dipyridamole echocardiography test (intravenous dipyridamole with two-dimensional echocardiographic monitoring) was performed in 93 patients with effort chest pain and in 10 control subjects. The test was considered positive when regional asynergy appeared after dipyridamole administration. When negative at the low dose (0.56 mg/kg body weight in 4 minutes), the test was repeated on a different day with a higher dose (0.84 mg/kg in 10 minutes). All 93 patients underwent coronary arteriography; 72 of them had significant (greater than 70% luminal reduction) coronary artery disease. Thirty-eight of the 93 patients had a positive low dose dipyridamole echocardiography test; 15 other patients with a negative low dose test had a positive high dose test. All 53 patients with a positive test had significant coronary artery disease; 12 of them had a negative exercise stress test. In relation to the presence of coronary artery disease, the dipyridamole echocardiography test had an overall specificity higher than that of the exercise stress test (100 versus 71%) and a similar overall sensitivity (74 versus 69%). The dipyridamole echocardiography test is feasible in all patients with a good baseline echocardiogram. It detects the site of apparent ischemia more precisely than does an exercise stress test, and can unmask electrocardiographically silent ischemia. If performed in patients with a negative low dose dipyridamole echocardiography test, the high dose test adds sensitivity (probably by achieving maximal dilation in patients in whom the low dose is only partially effective), without any loss in specificity and with no apparent increase in risk.     

Role of dipyridamole-echocardiography test in electrocardiographically silent effort myocardial ischemia

A frequent clinical problem is documentation of the elusive entity of "electrocardiographically silent" effort myocardial ischemia. In this study, 83 patients with angina on effort and either negative or nondiagnostic exercise stress test results underwent a dipyridamole-echocardiography (echo) test, a feasible and useful tool for detection of coronary artery disease (CAD). The dipyridamole-echo test (2-dimensional echocardiographic monitoring combined with intravenous dipyridamole infusion at a maximal dosage of 0.84 mg/kg over 10 minutes) and coronary arteriography were performed in all patients. Positivity of dipyridamole-echo test was based on the detection of regional transient asynergy of contraction. At coronary arteriography, 50 of the 83 patients had significant (more than 70% diameter reduction) CAD: 27 had 1-vessel, 17 had 2-vessel and 6 had 3-vessel CAD. Interpretable echocardiograms were recorded in all the patients studied. The dipyridamole-echo test results were positive in 27 of the 50 patients (54%) with CAD. No patient without CAD had a positive test result. In conclusion, the dipyridamole-echo test frequently unmasks electrocardiographically silent effort myocardial ischemia by providing objective mechanical evidence of the ischemic event.     

Evaluation of Diagnos Malaria Stix test (antigen detection assay) for diagnosis of malaria

Malaria is one of the most common parasitic infection in India. The diagnosis largely depends on peripheral blood smear examination. Newer diagnostic methods like various antigen detection assays are now in use for prompt diagnosis and treatment. This study was done to determine the effectiveness of Diagnos Malaria Stix (antigen detection) assay in diagnosis of malaria. This involves detection of PfHRP-2 antigen and P.V. specific pLDH antigen. 162 patients with signs and symptoms of malaria included in the study. Leishman stained blood smear examination was done for all patients. Commercially available Diagnos Malaria Stix assay was used. Diagnos Malaria Stix showed sensitivity, specificity positive and negative predictive values of 100% each while Sensitivity, specificity, positive and negative predictive values of Leishman stained blood smear examination were 45.45%, 100%, 100% and 92% respectively.