Biomedical subjects

A Distante

Publications and source records attributed to A Distante.

At least 91 records · Page 5Linked to original sources

PubMed1988

Dipyridamole echocardiography in essential hypertensive patients with chest pain.

The exercise-electrocardiography test shows limited feasibility and diagnostic accuracy for the noninvasive detection of coronary artery disease in hypertensive patients. Recently, the dipyridamole-echocardiography test (two-dimensional echocardiographic monitoring with dipyridamole infusion, up to 0.84 mg/kg over 10 minutes) has been proposed as an exercise-independent method for the diagnosis of coronary artery disease. The diagnostic usefulness of the exercise-electrocardiography test and the dipyridamole-echocardiography test was evaluated in 63 consecutive inpatients with history of chest pain, essential hypertension, and no previous myocardial infarction. The criterion of positivity for the exercise-electrocardiography test was a horizontal or downsloping ST segment shift exceeding 0.1 mV and for the dipyridamole-echocardiography test, a transient dyssynergy of contraction. Fifteen patients could not perform a diagnostic exercise-electrocardiography test because of an inability to exercise adequately (two patients), severe hypertension in spite of full antihypertensive therapy (six patients), or excessive blood pressure rise at the first step of the exercise-electrocardiography test (seven patients). Five patients could not perform the dipyridamole-echocardiography test because of a poor acoustic window. The overall feasibility was 76% for the exercise-electrocardiography test and 92% for the dipyridamole-echocardiography test (p less than 0.05). All 43 patients who performed both tests underwent coronary angiography; 30 had significant coronary artery disease (greater than 70% lumen reduction of at least 1 major coronary vessel). Sensitivity was 67% for both the exercise-electrocardiography test and the dipyridamole-echocardiography test (p = NS); specificity was 46% for the exercise-electrocardiography test and 92% for the dipyridamole-echocardiography test (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗

PubMed1987

Usefulness of a high-dose dipyridamole-echocardiography test for diagnosis of syndrome X.

This study assesses whether the high-dose dipyridamole-echocardiography test (DET, 2-D echocardiographic and 12-lead electrocardiographic monitoring during dipyridamole infusion, up to 0.84 mg/kg over 10 minutes) can help to identify patients with syndrome X. DET was performed in 10 control subjects (group A) and in 19 patients with syndrome X (group B). Patients in group B had chest pain on effort, a positive exercise stress response (more than 0.1 mV of ST-segment depression), negative ergonovine test response and normal left ventricular function and coronary angiographic findings. During DET no subject in group A showed transient asynergy or ST-segment depression and none had chest pain; in group B, no patient had transient asynergy, 13 (68%) had chest pain and 16 (84%) had more than 0.1 mV of ST-segment depression. Percent fractional shortening was not significantly different in the 2 study groups, either basally (group A, 35 +/- 7; group B, 37 +/- 8) or at peak hyperkinesia during DET (group A, 48 +/- 8; group B, 54 +/- 10). Thus, dipyridamole-induced chest pain and ST-segment depression in patients with syndrome X are not associated with impaired regional or global left ventricular function. This entity of echocardiographically silent myocardial ischemia during DET may be a clue to noninvasive detection of syndrome X.

Adult↗

PubMed1987

Comparison of the high-dose dipyridamole-echocardiography test and exercise two-dimensional echocardiography for diagnosis of coronary artery disease.

Fifty-five patients with effort angina pectoris and technically satisfactory baseline echocardiograms performed a supine exercise-echocardiography test (EET) and a high-dose dipyridamole-echocardiography test (DET, up to 0.84 mg/kg of intravenous dipyridamole in 10 minutes). All underwent coronary arteriography, which showed that at least 1 major artery had more than 70% stenosis in 34 patients. For each patient, the same physician performed both tests, with the same echocardiographic equipment. Detection of new onset or worsening regional asynergy was the only criterion of positivity for both tests. DET yielded interpretable studies in all 55 patients (100%); EET yielded only 40 such studies (73%) (p less than 0.01). In the 40 patients in whom both tests were interpretable, DET showed, compared with EET, a similar sensitivity (72% vs 76%) and specificity (100% vs 87%) (difference not significant for both) for detecting angiographically assessed coronary artery disease. In the 16 patients in whom both DET and EET yielded positive responses for ischemia, the same myocardial region showed reversible asynergy. Thus, independent of all factors that can affect the performance of each test (operator, patient and instrumentation), DET was significantly more feasible than EET, with comparable sensitivity and specificity. Dipyridamole provokes asynergy in the same regions that show ischemia during exercise.

Adult↗

PubMed1987

Different degrees of ischemic threshold stratified by the dipyridamole-echocardiography test.

Dipyridamole-echocardiography (echo) testing, exercise stress testing and coronary arteriography were performed in 141 patients with effort chest pain. Patients were separated into 5 groups according to the dose of dipyridamole needed to induce ischemia (0.56 mg/kg over 4 minutes vs 0.84 mg/kg over 10 minutes) and to the time of onset of the asynergy with the small dose (within vs beyond 3 minutes after the end of dipyridamole administration): group 1--early positive response to a small dose (33 patients); group 2--late positive response to a small dose (29 patients); group 3--negative response to a small dose, positive response to a large dose (17 patients); group 4a--negative response to both large and small doses, with significant coronary artery disease (CAD) (32 patients); and group 4b--negative response to small and large doses, without CAD (30 patients). All patients in groups 1, 2 and 3 had significant CAD. The rate-pressure product on exercise stress testing was measured at 0.10 mV of ST-segment shift in patients with a positive response and at peak exercise in patients with a negative response. Rate-pressure product significantly separated group 1 and group 2 from each other (157 +/- 46 and 229 +/- 33 mm Hg X beats/min X 1/100, respectively, mean +/- standard deviation) and from group 3, group 4a and group 4b (284 +/- 40, 290 +/- 51, and 298 +/- 45 mm Hg X beats/min X 1/100); values in the 3 latter groups overlapped.2+ Thus, the dipyridamole-echo test can stratify groups of patients with different levels of ischemia threshold on effort.

Adult↗

PubMed1987

Does the combination with handgrip increase the sensitivity of dipyridamole-echocardiography test?

The aim of this study was to assess the possibility of increasing the sensitivity of dipyridamole-echocardiography testing (DET:2-D echo monitoring during dipyridamole infusion) by combining this procedure with handgrip testing. Dipyridamole-handgrip test (DHT) was therefore performed in 24 patients with rest/effort angina, negative DET, and negative handgrip-echo (without dipyridamole pretreatment). DHT consisted of 4.5 min of sustained 25% maximum grip strength, started 4 min after the end of dipyridamole infusion (0.56 mg/kg for 4 min). Interpretable studies were obtained in all patients. Of the 24 patients tested (10 without and 14 with significant coronary artery disease, CAD), only one CAD patient had a positive DHT, which indicates an increased sensitivity of 7% versus DET alone. In conclusion, DHT is feasible in all patients and--if compared to DET--has the same specificity. However, in spite of the theoretical premises, it provides only a modest step up in sensitivity.

Angina Pectoris↗

PubMed1987

Short-term reproducibility of dipyridamole-echocardiography test.

The aim of this study was to assess the short-term reproducibility of dipyridamole-echocardiography test (DET) consisting of two-dimensional echo monitoring during dipyridamole infusion (up to 0.84 mg/kg in 10 min). The diagnostic end-point of the test is the detection of new onset or worsening regional asynergy. A group of 87 patients with rest and/or effort angina performed two DETS on two consecutive days. All 60 patients with a positive DET had a positive repeat test, and the 27 negative DETs were also negative on the following day. The timing of the asynergy was also very similar between the two tests, both in patients with angina on effort (r = .93, p less than 0.01) and at rest (r = .92, p less than 0.01). In conclusion, DET has a very high short-term reproducibility regarding the presence and timing of asynergy.

Angina Pectoris↗

PubMed1987

Limitations of digital subtraction contrast echocardiography in enhancing left ventricular endocardial definition.

The purpose of this study was to evaluate whether the digital subtraction technique, applied to contrast echocardiography of the left ventricle (LV), might improve endocardial edge identification by two-dimensional echocardiography. Injections of the polysaccharide agent SHU-454 were made into the LV of five closed-chest dogs. Data were obtained at different levels of ejection fraction (EF) induced by pharmacologic or mechanical interventions and were documented by left ventriculography (VGRAM) in the right anterior oblique projection. Contrast echocardiography was recorded in the apical four-chamber view. The echocardiographic images were digitized off-line into a 256 X 256 pixel matrix with 256 gray levels/pixel. Two end-diastolic frames prior to contrast appearance were averaged to obtain a mask that was subtracted from end-diastolic contrast frames corresponding to the two beats of peak intensity. The same procedure was repeated for the systolic frames. LV edges from echocardiographic images prior to contrast appearance, from digitally subtracted echo-contrast images, and from VGRAM were traced on two occasions by two different observers. LV volumes were calculated by single-plane Simpson's rule and EF was derived by the classical equation. The intra- and interobserver reproducibility in the measurement of EF was excellent for VGRAM (r = 0.95 and 0.94, respectively), it was good for two-dimensional echocardiography (r = 0.87 and 0.73), and was fair for contrast-echo (r = 0.79 and 0.68).(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗

PubMed1987

In vitro identification of different degrees of mitral valve disease by online evaluation of radiofrequency ultrasound signal.

Sixty five mitral valves were studied in vitro with a 2.25 MHz transducer. Radiofrequency signals were analysed by a microprocessor system (implemented on an M-mode commercially available echocardiography) for online evaluation of ultrasonic backscatter (8 bits of amplitude resolution, 40 MHz sampling rate, 1 microsecond acquisition gate). The integrated value of the rectified signal amplitude was expressed as the integrated backscatter index (in db). The highest value recorded with ultrasonic scanning of each sample was taken as representative of that specimen. Calcification of mitral valves was assessed by radiography (24 mitral valves). Non-calcified mitral calves underwent pathological examination, and fibrotic valves (22 mitral valves) were differentiated from normal valves (19 mitral valves). A statistically significant (p less than 0.005) difference was recorded among the three groups for the index maximal value: calcific -7.4(3.1) db (mean(SD)), fibrotic -18.9(4.9) db, and normal -37.9(7.6) db. In conclusion, a microprocessor based system for online evaluation of radiofrequency ultrasonic signals, which may also be feasible for in vivo studies, provided a clear differentiation in vitro of calcific, fibrotic, and normal mitral valves.

Calcinosis↗

PubMed1987

Dipyridamole-echocardiography test as a clue for assessing the organic 'ceiling' of individual coronary reserve.

Twenty-four patients with a history of effort angina, a positive exercise stress test (EST) and coronary artery disease were enrolled in the study; 12 patients had a positive dipyridamole-echocardiography test (DET) and 12 had a negative DET. Each patient performed a total of 4 ESTs in the absence of therapy on two successive days; for each test the rate-pressure product (RPP), an established index of myocardial oxygen demand, was measured at the onset of ischaemia (ST depression greater than 0.15 mV) or at the peak of maximal exercise (if a repeated EST was negative). Taking into account the lowest of the 4 RPP values (X 1/100) in each patient, there was no significant difference between DET-negatives and DET-positives (185.2 +/- 49.3 vs 157.4 +/- 32.4). Conversely, when considering the highest of the 4 RPP values in each patient, there was a significant difference between DET-negatives and DET-positives (280.3 +/- 63.9 vs 183.3 +/- 37.0; p less than 0.01). Thus, DET may provide a clinically useful tool for assessing in the individual the organic 'ceiling' of coronary reserve, by eliminating the variability in coronary tone, which may affect EST reproducibility and the correct evaluation of the impairment of organic coronary reserve.

Adult↗

PubMed1987

Oral isosorbide 5-mononitrate can protect from myocardial ischemia induced by ergonovine test and by isometric effort. Preliminary results from an echocardiographic acute study in anginal patients.

Isosorbide 5-mononitrate (IS 5-MN) has favourable pharmacodynamic properties, such as the specific half-life (close to 5 h) and the bioavailability (100% after oral ingestion). The efficacy of IS 5-MN (20 mg t.i.d.) in the treatment of stable angina has been documented in previous studies. In the present acute study, two subsets of patients were evaluated: the first group consisted of 10 patients with coronary vasospasm in whom oral IS 5-MN was effective in preventing myocardial ischaemia due to an abrupt reduction in coronary blood flow; the second group regarded 8 patients with a mixed form of angina, where the responsible mechanism for ischaemia can be considered a combination of increased myocardial oxygen demand and reduction of coronary blood flow due to vasoconstriction of large vessels. In all these patients, IS 5-MN was able to protect against transient myocardial ischaemia induced by isometric test. In conclusion, from the data available in our studies, IS 5-MN appears to be a useful drug in anginal patients: the beneficial effect is likely based on its capability both to prevent the abnormal vasoconstriction of diseased coronary vessels and to reduce myocardial oxygen demand.

Administration, Oral↗

PubMed1986

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.

Adult↗

PubMed1986

Dipyridamole-echocardiography test in patients with exercise-induced ST-segment elevation.

Fourteen consecutive patients with exercise-induced ST-segment elevation in the absence of previous infarction and basal left ventricular asynergy at rest performed a dipyridamole test (infusion of dipyridamole, 0.14 mg/kg/min intravenously for 4 minutes) during 12-lead electrocardiographic (ECG) and 2-dimensional echocardiographic monitoring. In 7 of the 14 patients, dipyridamole infusion consistently induced ST-segment elevation in the leads that showed ST elevation on effort; reversible asynergy (occurring in the region corresponding to the ECG leads with diagnostic changes) could always be documented by echocardiography. In 2 patients dipyridamole induced reversible asynergy in presence of ST-segment depression. In these 9 patients angiography invariably revealed a severe organic stenosis in the coronary artery feeding the region that became transiently asynergic after dipyridamole. In the other 5 patients (all of whom had either spontaneous or ergonovine-induced ST-segment elevation), the dipyridamole test yielded no significant echocardiographic or ECG change; coronary angiography showed absent (2 patients) or significant (3 patients) coronary artery disease. In conclusion, dipyridamole may induce transmural ischemia in humans, as detected by the electrical hallmark of ST elevation; this ECG pattern, in contrast to ST depression, reliably predicts the presence and site of transient regional asynergy. When dipyridamole induces ST-segment elevation, severe basal stenosis is invariably present in the coronary artery supplying the transiently asynergic myocardial region.

Adult↗

PubMed1986

Dipyridamole-echocardiography test in angina at rest: noninvasive assessment of coronary stenosis underlying spasm.

In a previous study performed in patients with effort angina pectoris, we showed that the dipyridamole-echocardiography test (DET) is feasible and useful for the detection of coronary artery disease. The positivity of the test (consisting of two-dimensional echocardiography [2 DE] combined with dipyridamole infusion [0.14 mg/kg/min for 4 minutes]) is linked to the appearance of regional asynergy. In the present study, DET and exercise stress test (EST) were performed in 62 patients with angina at rest in the active phase. The overall sensitivity of DET and EST for the detection of coronary artery disease was 62% and 83%, respectively (p less than 0.05); the specificity of DET and EST was 100% and 64%, respectively (p less than 0.05). In 10 DET-positive patients, a spontaneous attack was also monitored by 2DE; the myocardial wall involved by ischemia was invariably the same both in patients with spontaneous and in those with dipyridamole-induced ischemia. Thus, in our population of patients with angina at rest (in whom an important functional component is also likely to be present during exercise), DET was significantly less sensitive but significantly more specific than EST in detecting coronary artery disease.

Adult↗

PubMed1986

Transient myocardial dysfunction during pharmacologic vasodilation as an index of reduced coronary reserve: a coronary hemodynamic and echocardiographic study.

Regional coronary flow reserve and regional myocardial contractility were evaluated in 29 patients after maximal pharmacologic coronary vasodilation (intravenous dipyridamole, 0.56 mg/kg body weight, administered over 4 minutes). Nineteen patients had a severe (80 to 99%) proximal and isolated stenosis of the left anterior descending coronary artery and 10 patients had normal coronary arteries; all had normal ventricular function under rest conditions. Myocardial contractility was assessed by means of continuous two-dimensional echocardiographic monitoring; coronary reserve was evaluated by coronary sinus thermodilution. After dipyridamole infusion, 9 of the 19 patients with left anterior descending artery stenosis had transient myocardial asynergy involving the septum or apex, or both (Group IA), whereas 10 patients showed no asynergy (Group IB). No impairment of contractility was observed in the 10 patients with normal coronary arteries (Group II). Coronary blood flow was measured under basal conditions and up to 10 minutes after the end of dipyridamole infusion. In patients in Group II, dipyridamole induced an increase in great cardiac vein flow of 167 +/- 68% (mean +/- SD). The 10 patients in Group IB showed a response comparable with that of the control group (Group II) (136 +/- 45% increase in great cardiac vein flow; NS versus Group II), whereas the 9 patients in Group IA had an increase of 46 +/- 30% (p less than 0.01 versus both Group IB and Group II). No significant difference was found in the angiographic severity of the stenosis expressed in terms of minimal cross-sectional area (Group IA = 0.30 +/- 0.13 mm2, Group IB = 0.34 +/- 0.18 mm2; p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1986

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.

Adult↗

PubMed1986

Early post-infarction angina: usefulness of dipyridamole-echocardiography test.

Thirty-nine patients with early post-infarction angina (all with significant, angiographically assessed coronary artery disease and a baseline asynergy on 2-D echo), performed a dipyridamole-echocardiography test (DET: 2-D echo monitoring with dipyridamole infusion, 0.14 mg kg-1 min-1 for 4 min). Twenty-nine patients had a positive DET (sensitivity = 74%). Two mechanical patterns of DET-positivity could be identified: a worsening of the asynergy in that same region showing a baseline asynergy (11 patients); a 'de novo' asynergy in a region remote from the one showing a baseline asynergy (18 patients); The prevalence of single-vessel disease was significantly higher in patients with type 1 positivity pattern (6 single-, three double- and two triple-vessel disease), while patients with type 2 positivity always showed a multivessel coronary involvement (8 double-, 10 triple-vessel disease). In 4 of the 10 patients with 3-vessel disease and type 2 asynergy, such asynergy developed in a territory different from the one supplied by the more stenotic non-infarct-related vessel. In conclusion, DET represents a safe and feasible tool effectively to localize ischaemia, relative to the infarcted region, and to evaluate the haemodynamic significance of coronary lesions in patients with post-infarction angina.

Adult↗

PubMed1986

The use of frequency histograms of ultrasonic backscatter amplitudes for detection of atherosclerosis in vitro.

This study was designed to determine whether a quantitative analysis of integrated backscatter amplitude distribution is potentially useful in characterizing the atherosclerotic lesion. One hundred measurements (10 X 10 array) were made in fresh aortic regions (2 cm X 2 cm) of nine normal and 19 atherosclerotic arterial walls. A 10 MHz transducer was used. The integrated backscatter distinguished normal from atherosclerotic specimens (-56.7 +/- 4.3 vs -42.5 +/- 8.9 dB, p less than .01). The shape of the integrated backscatter amplitude distribution was analyzed by calculation of skewness and kurtosis of each arterial region. Both skewness values (0.134 +/- 0.325 vs -0.193 +/- 0.491 in normal and atherosclerotic segments, respectively, p = NS) and kurtosis values (0.055 +/- 0.765 vs -0.610 +/- 0.379, p less than .01) discriminated between the two groups. When only the six atherosclerotic specimens with mostly fatty and fibrofatty sites were considered, skewness and kurtosis still distinguished normal from atherosclerotic regions (0.134 +/- 0.325 vs -0.404 +/- 0.232, p less than .05 and 0.055 +/- 0.765 vs -0.558 +/- 0.337, p less than .05, respectively), while integrated backscatter values did not (-56.7 +/- 4.5 vs -52.3 +/- 6.1 dB, p = NS). In conclusion, atherosclerosis may be detected in vitro by the quantitative analysis of integrated backscatter distribution. This variable could also be of help in the identification of less obvious forms of atherosclerotic disease that are not distinguishable on the basis of integrated backscatter amplitude.

Aorta↗

PubMed1986

The therapeutic role of isosorbide-5-mononitrate+ in stable and unstable angina pectoris.

Various studies on the pharmacodynamic and clinical properties of isosorbide-5-mononitrate (IS-5-MN) indicate that this drug is effective in the treatment of stable angina pectoris. Acute and chronic studies, in fact, show an improved performance and an amelioration of the clinical status in patients under treatment. On the other hand, acute studies on vasospastic and mixed angina, two common clinical manifestations of coronary artery disease, have demonstrated the capability of IS-5-MN in preventing episodes of transient myocardial ischemia. In analogy with other forms of nitrates, it is clear that IS-5-MN has a positive effect both on the coronary tree (preventing vasoconstriction) and on those hemodynamic parameters which influence the myocardial oxygen demand (reducing myocardial oxygen consumption). Further information is needed, however, to clarify the issue of tolerance development after chronic administration; so far it appears that tolerance may develop when patients are treated with doses of IS-5-MN greater than 20 mg t.i.d.. On the basis of the clinical studies carried out with IS-5-MN, and its favourable pharmacological profile, it is foreseeable that this drug will have an increasing role in the treatment of angina pectoris.

Angina Pectoris↗