PubMed Health⌕ Search

Biomedical subjects

A Distante

Publications and source records attributed to A Distante.

At least 37 records · Page 2Linked to original sources
PubMed1995

Transesophageal echocardiography in myocardial ischemia: a review.

This article reviews established as well as emerging fields in the application of transesophageal echocardiography (TEE) in the investigation of myocardial ischemia. TEE already has a well defined and established role in stress echocardiography in patients with poor transthoracic acoustic window, and in the detection of intraoperative myocardial ischemia in cardiac and noncardiac surgery. The evaluation of right ventricular ischemia and infarction and the assessment of coronary flow reserve (CFR) are relatively new fields in the application of TEE and the potential of this technique has not yet been fully evaluated. The evidence collected and reviewed in this article is still preliminary but it presupposes a significant role of TEE in the diagnosis and pathophysiological assessment of myocardial ischemia.

Echocardiography, Transesophageal↗
PubMed1994

Dipyridamole-dobutamine echocardiography: a novel test for the detection of milder forms of coronary artery disease.

OBJECTIVES: This study was designed to assess the clinical, hemodynamic and diagnostic effects of the addition of dobutamine to dipyridamole echocardiography. BACKGROUND: Pharmacologic stress echocardiography with either dipyridamole or dobutamine has gained acceptance because of its safety, feasibility, diagnostic accuracy and prognostic power. The main limitation of the two tests is a less than ideal sensitivity in some patient subsets, such as those with limited coronary artery disease. We hypothesized that two pharmacologic stresses might act synergistically in the induction of ischemia by combining the mechanisms of inappropriate coronary vasodilation (with dipyridamole) and an increase in myocardial oxygen consumption (with dobutamine). METHODS: One hundred fifty patients (mean [+/- SD] age 51 +/- 11 years) referred for stress echocardiography were initially studied by dipyridamole-dobutamine echocardiography. The test was stopped during the dipyridamole step in 95 patients for achievement of a predetermined end point (obvious dyssynergy induced by lower or higher dipyridamole dose), and dipyridamole-dobutamine tests were performed in 55 patients (negative dipyridamole echocardiographic test). In the same 150 patients the dobutamine echocardiographic test (up to 40 micrograms/kg body weight per min) was performed on a separate day. RESULTS: Significant coronary artery disease (> 50% diameter stenosis of at least one major coronary vessel by quantitative coronary arteriography) was present in 131 patients (one vessel in 115; two vessels in 10, three vessels in 6), with normal coronary arteriography in 19. The feasibility of the dipyridamole-dobutamine test was 96%. Self-limiting side effects occurred in 5% of patients. The peak rate-pressure product was lowest during the dipyridamole test (132 +/- 30) and was comparable during the dobutamine (186 +/- 59) and dipyridamole-dobutamine tests (179 +/- 45, p = NS vs. dobutamine; p < 0.01 vs. dipyridamole). Sensitivity was 71% for dipyridamole, 75% for dobutamine and 92% for dipyridamole-dobutamine echocardiography (dipyridamole vs. dipyridamole-dobutamine, p < 0.01; dobutamine vs. dipyridamole-dobutamine, p < 0.01; dipyridamole vs. dobutamine, p = NS), whereas specificity was 89% for dipyridamole, 79% for dobutamine and 89% for dipyridamole-dobutamine echocardiography (p = NS for all). CONCLUSIONS: Routine dobutamine addition to dipyridamole stress testing is clinically useful and well tolerated. It expands the spectrum of the disease detectable by pharmacologic stress echocardiography and allows documentation of milder forms of coronary artery disease that can be missed by conventional dipyridamole or dobutamine stress echocardiography.

Adult↗
PubMed1994

Analysis of right ventricular kinesis by means of transesophageal echocardiography: present problems and perspectives.

The evaluation of right ventricular (RV) kinesis by two-dimensional echocardiography represents a difficult task. Transthoracic echocardiography can visualize the RV in several projections, but the image quality and the variability of imaging views usually do not allow quantitative analysis. We investigated the potential of transesophageal echocardiography (TEE) for evaluating RV global function and regional kinesis, in 32 controls and in 16 patients with inferior myocardial infarction (MI) and asynergy involving the inferior wall of both ventricles. Good-quality images of at least one horizontal section of the RV were obtained in 73% of subjects by conventional, 90 degrees sector and in 100% of subjects by wide-angle, "panoramic" sector. Images of the RV in short-axis view at medium level were acquired and evaluated in 93% of cases, but at basal and apical levels only in 67% and 39%, respectively. The low percentage of successful detection and evaluation of the RV at apical level can be explained by prominent motion and trabeculation of the apex. Global systolic area changes (SAC) in controls attained similar values at apical and medium levels (60% and 59%, respectively), but were significantly lower (48%, P less than 0.05) at basal level. In patients with previous inferior MI and inferoposterior asynergy, global SAC were significantly (P less than 0.01) lower at medium and basal levels (32% and 27%, respectively) compared with controls. Regional kinesis of RV was assessed as segmental SAC in 12 different segments, by fixed and float system of center of cavity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Assessment of anatomic and physiological severity of single-vessel coronary artery lesions by dipyridamole echocardiography. Comparison with positron emission tomography and quantitative arteriography.

BACKGROUND: The aim of this study was to compare the results of dipyridamole-echocardiography test (DET: two-dimensional echo monitoring during dipyridamole infusion up to 0.84 mg/kg over a period of 10 minutes) with both anatomic and physiological parameters of coronary artery disease severity, assessed by computer-assisted quantitative coronary arteriography, and regional coronary flow reserve, measured by [13N]ammonia (13NH3) and dynamic positron emission tomography (PET), respectively. METHODS AND RESULTS: We studied 31 patients with a history of chest pain and neither previous myocardial infarction nor resting wall motion abnormalities. Eighteen patients had single-vessel disease (> 50% stenosis of one major coronary vessel), and 13 had normal coronary arteries. The criterion for DET positivity was the appearance of a new transient regional wall motion abnormality. In patients with a positive DET, two parameters were evaluated: the dipyridamole time (ie, the time from the beginning of drug infusion to the development of obvious dyssynergy) and 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 segments interpreted. Quantification of regional myocardial blood flow was obtained by PET measurements of 13NH3 arterial input function and left ventricular myocardial tissue concentration both at control and after dipyridamole (0.56 mg/kg over 4 minutes). Maximal regional blood flow after dipyridamole in the region supplied by the stenotic vessel was significantly lower in the 11 patients with coronary artery disease and positive DET than in the 7 patients with coronary artery disease and negative DET (1.08 +/- 0.33 versus 1.98 +/- 0.37 mL.min-1.g-1, P < .01). In patients with a positive DET, regional coronary flow reserve correlated well with dipyridamole time (r = .87, P < .01) but not with peak WMSI (r = .25, P = NS). Patients with dipyridamole-induced akinesia or dyskinesia (n = 6) had a greater reduction in regional coronary flow reserve than did those showing hypokinesia (n = 5): 1.38 +/- 0.51 versus 2.17 +/- 0.42, P < .05. Percent area reduction was more severe in patients with DET positivity than in those with DET negativity (93.7 +/- 8.7% versus 77 +/- 10.3%, P < .01), and it correlated with regional coronary flow reserve (r = .64, P < .01) and dipyridamole time (r = -.59, P < .01). CONCLUSIONS: In patients with single-vessel disease, DET shows an excellent specificity but a limited sensitivity; in these patients, DET positivity is associated with a physiologically important coronary stenosis. Severity of the anatomic stenosis and impairment in regional flow reserve are greater when the dipyridamole-induced dyssynergy appears earlier during the test. Therefore, a stratification of the anatomo-physiological severity of coronary artery disease can be obtained with DET, based mainly on the temporal allocation of the transient dyssynergy.

Adult↗
PubMed1994

Diagnostic and prognostic value of dipyridamole echocardiography in patients with suspected coronary artery disease. Comparison with exercise electrocardiography.

BACKGROUND: Before any new diagnostic test is accepted in clinical practice, such a test should be compared with established diagnostic tools in an appropriately large series of patients encompassing the complete spectrum of challenges to which the test is exposed. The aim of the present study was to assess the relative diagnostic and prognostic accuracies of high-dose dipyridamole echocardiography (two-dimensional echocardiographic monitoring during dipyridamole infusion up to 0.84 mg/kg over 10 hours) versus maximal symptom-limited bicycle exercise ECG test in patients with angina. METHODS AND RESULTS: We studied 429 consecutive in-hospital patients who met the following inclusion criteria: history of chest pain, off antianginal therapy for at least 2 days (1 week for beta-blockers), no previous myocardial infarction and/or obvious regional left ventricular dyssynergy of contraction (akinesis or dyskinesis) at baseline, and acceptable acoustic window under resting conditions. All patients underwent dipyridamole echocardiography and exercise ECG--on different days and in random order--within 1 week of coronary angiography (which was performed independent of test results) and were followed up for 37.8 +/- 14 months (range, 1 to 73 months). Criteria of positivity were for dipyridamole echocardiography, a transient regional dyssynergy absent in the baseline examination; for exercise ECG, an ST-segment shift of > or = 0.1 mV from baseline; and for coronary angiography, a luminal reduction of > or = 75% in at least one major coronary vessel (50% for left main). There were 183 patients without and 246 with coronary artery disease; 132 had one-, 70 had two-, and 44 had three- and/or left main vessel disease. The specificity was higher for dipyridamole echocardiography than for exercise ECG (90% versus 51%, P < .001). The overall sensitivity of dipyridamole echocardiography was similar to that of exercise ECG (75% versus 74%, P = NS), with no significant differences in the subset with one- (67% versus 69%, P = NS), two- (79% versus 77%, P = NS), or three- (93% versus 86%, P = NS) vessel disease. During the follow-up, there were 20 deaths, 13 nonfatal myocardial infarctions, and 126 revascularization procedures. In the univariate analysis, dipyridamole resulted in higher chi 2 values than did exercise stress testing. A Cox forward stepwise survival analysis identified the dipyridamole time as the most powerful prognostic predictor of death (chi 2 = 19.4, P < .0001) of all invasive and noninvasive parameters. The dipyridamole time also provided independent and additional prognostic information when it was adjusted for age, diabetes, resting ECG, and exercise stress test according to a modified, interactive stepwise procedure. This is true when death only, death and myocardial infarction, and death, myocardial infarction, and revascularization procedures were considered end points. CONCLUSIONS: In patients with no previous myocardial infarction and good resting left ventricular function, compared with exercise ECG, dipyridamole echocardiography has a similar sensitivity and a higher specificity for the noninvasive detection of angiographically assessed coronary artery disease. Dipyridamole echocardiography also provides information in addition to that provided by exercise ECG for predicting death, infarction, and all events when the presence as well as the timing, severity, and extension of dipyridamole-induced wall motion abnormalities are considered.

Coronary Angiography↗
PubMed1993

Value of rest thallium-201/technetium-99m sestamibi scans and dobutamine echocardiography for detecting myocardial viability.

The relation between radioisotopic and echocardiographic markers of myocardial viability and postrevascularization recovery of function is still to be defined. To this purpose, 14 patients (11 men, 3 women, aged 35 to 64 years, mean 54 +/- 7) with ventricular dysfunction were studied by a multiparametric approach. Each patient underwent, on separate days, rest thallium-201 and technetium-99m sestamibi scintigraphy, dobutamine echocardiography and coronary angiography. Coronary angiography was analyzed by a quantitative approach. Thallium uptake at rest was quantified from planar early (10-minute) and delayed (16-hour) thallium-201 images and expressed as a percentage of maximal activity in each projection using a 13-segment model. Sestamibi uptake was expressed in the same way. Dobutamine (up to 10 micrograms/kg/min) echocardiography was analyzed using a score index ranging from 1 (normokinesia) to 4 (dyskinesia) and a similar segmental model. Before revascularization 50 segments were grouped as normal (coronary stenosis < 50% and normal function, group 1); of the remaining 132 segments with > 50% coronary stenosis, 57 had normal wall motion (group 2) and 75 showed regional dyssynergies (group 3). Early and delayed thallium-201 regional percent activities did not differ in group 1 and in group 2 but were significantly less in group 3 segments. Sestamibi percent activity was more in group 1 and significantly reduced both in group 2 and 3 segments. Segments with improved wall motion after dobutamine had more early, delayed thallium-201 and sestamibi percent activities than unresponsive segments. Postrevascularization echocardiography was performed in all patients. Delayed thallium-201 scans and dobutamine echocardiography showed good sensitivity and specificity in detecting viable myocardium. (ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Angiography↗
PubMed1993

Flow quantitation by radio frequency analysis of contrast echocardiography.

Contrast echocardiography has the potential for measuring cardiac output and regional blood flow. However, accurate quantitation is limited both by the use of non-standard contrast agents and by the electronic signal distortion inherent to the echocardiographic instruments. Thus, the aim of this study is to quantify flow by combining a stable contrast agent and a modified echo equipment, able to sample the radio frequency (RF) signal from a region of interest (ROI) in the echo image. The contrast agent SHU-454 (0.8 ml) was bolus injected into an in vitro calf vein, at 23 flow rates (ranging from 376 to 3620 ml/min) but constant volume and pressure. The ROI was placed in the centre of the vein, the RF signal was processed in real time and transferred to a personal computer to generate time-intensity curves. In the absence of recirculation, contrast washout slope and mean transit time (MTT) of curves (1.11-8.52 seconds) yielded excellent correlations with flow: r = 0.93 and 0.95, respectively. To compare the accuracy of RF analysis with that of conventional image processing as to flow quantitation, conventional images were collected in the same flow model by two different scanners: a) the mechanical sector scanner used for RF analysis, and b) a conventional electronic sector scanner. These images were digitized off-line, mean videodensity inside an identical ROI was measured and time-intensity curves were built. MTT by RF was shorter than by videodensitometric analysis of the images generated by the same scanner (p < 0.001). In contrast, MTT by RF was longer than by the conventional scanner (p < 0.001). Significant differences in MTT were also found with changes in the gain setting controls of the conventional scanner. To study the stability of the contrast effect, 6 contrast injections (20 ml) were performed at a constant flow rate during recirculation: the spontaneous decay in RF signal intensity (t1/2 = 64 +/- 8 seconds) was too long to affect MTT significantly. In conclusion, the combination of a stable contrast agent and a modified echocardiographic instrument provides accurate quantitation of flow in an in vitro model; RF analysis is more accurate than conventional processing as to flow quantitation by contrast echocardiography.

Animals↗
PubMed1993

Flow quantitation by contrast echocardiography. Effects of intervening tissue and of the angle of incidence between flow and ultrasonic beam.

The combination of a standardized echographic contrast agent with the analysis of the ultrasonic radio frequency (RF) signal allowed in vitro flow quantitation in a circulation model. The purpose of this study was to investigate both the effects of biological tissues, intervening between probe and insonated structure, and the effects of the angle of incidence between flow and ultrasonic beam on RF flow quantitation. Thus, the contrast agent SHU 454 was intravenously injected (0.4 ml) as a bolus into a circulation model, at variable flow rates, while keeping the pressure and volume of the vessel constant. Injections were performed with saline interposed between probe and vessel and after the addition of the subcutaneous tissue of a pig; injections were also performed using the probe normal to the flow and with an angle of incidence of 45 degrees. Echographic data were recorded by a mechanical sector scanner, capable of sampling the RF signal from a region of interest positioned in the center of the vein. Contrast echo time-intensity curves were generated. As expected, both peak intensity and the area under the curves decreased with intervening tissue (-58 and -70% of baseline values, respectively, p < 0.001). Surprisingly, mean transit time also decreased with intervening tissue (from 1.12 +/- 0.25 seconds with saline, to 0.92 +/- 0.13 seconds with tissue, p < 0.001), thus producing a systematic overestimation of flow (21% on the average). To compensate for signal attenuation, contrast injections were repeated in the presence of tissue after increasing the electronic signal amplification (10 dB), and transit time did not significantly differ from control.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Intracoronary air-filled albumin microspheres for myocardial blood flow measurement.

OBJECTIVES: The aim of this study was to explore the possibility of quantifying coronary blood flow by myocardial contrast echocardiography with air-filled serum albumin microspheres (Albunex). BACKGROUND: Air-filled albumin microspheres have been proposed as an intravascular tracer for the study of myocardial perfusion by contrast echocardiography. METHODS: In six anesthetized open chest dogs, the left circumflex coronary artery was cannulated and perfused by a roller pump with blood from the femoral artery. Both air-filled albumin microspheres (0.4 ml, 2 x 10(8) spheres/ml) and technetium-99m-labeled albumin were injected as a bolus into the coronary cannula at baseline and after treatment with dipyridamole (0.56 mg/kg body weight intravenously for 4 min). Two-dimensional echographic images of the left ventricular short axis were digitized to generate myocardial time-intensity curves; myocardial radioactivity was measured by an external detector to generate radionuclide time-activity curves. RESULTS: After dipyridamole, left circumflex coronary artery blood flow (as measured by both the pump and an electromagnetic flow meter) significantly increased (from 1.06 +/- 0.28 to 3.61 +/- 1.43 ml/min per g of myocardium). Peak intensity and rise time of contrast echo curves were able to differentiate baseline myocardial perfusion from coronary hyperemia but did not show any significant correlation with coronary blood flow. A weak inverse correlation with coronary blood flow was provided by myocardial mean transit time of air-filled albumin microspheres (r = 0.33). Conversely, a close inverse correlation with coronary blood flow was obtained by myocardial mean transit time of technetium-99m-labeled albumin (r = 0.95). Myocardial transit time of air-filled albumin microspheres (1.95 +/- 0.60 s) was also markedly shorter than that of labeled albumin (5.35 +/- 3.43 s, p < 0.001) and the measurements were less reproducible. CONCLUSIONS: In this experimental study, coronary blood flow was not adequately quantified by myocardial contrast echocardiography with intracoronary injection of air-filled albumin microspheres.

Albumins↗
PubMed1993

SIMD parallelization of the WORDUP algorithm for detecting statistically significant patterns in DNA sequences.

The development of new techniques in sequencing nuclei acids has produced a great amount of sequence data and has led to the discovery of new relationships. In this paper, we study a method for parallelizing the algorithm WORDUP, which detects the presence of statistically significant patterns in DNA sequences. WORDUP implements an efficient method to identify the presence of statistically significant oligomers in a non-homologous group of sequences. It is based on a modified version of the Boyer-Moore algorithm, which is one of the fastest algorithms for string matching available in the literature. The aim of the parallel version of WORDUP presented here is to speed up the computational time and allow the analysis of a greater set of longer nucleotide sequences, which is usually impractical with sequential algorithms.

Algorithms↗
PubMed1993

Effects of coronary blood flow on myocardial grey level amplitude in two dimensional echocardiography: an experimental study.

OBJECTIVE: The aims were: (1) to evaluate whether differences in absolute and cyclic echocardiographic image amplitude exist in different layers (subendocardium and subepicardium) and regions (septal, anterior, lateral, inferior wall) of the canine left ventricle; (2) to assess the dependence of these variables upon local variations of coronary blood flow. METHODS: In six anaesthetised open chest dogs the circumflex coronary artery was cannulated and perfused by a roller pump with blood from their own femoral artery. Maximum coronary vasodilatation was obtained by continuous adenosine infusion. The absolute values and the transmural distribution of coronary blood flow were measured by radionuclide labelled microspheres. Echo images were obtained in short axis view by a commercially available electronic sector scanner with a 5.0 MHz transducer directly placed on the epicardial surface of the right ventricle, and digitised off-line into a matrix of 256 x 256 pixels with 25% grey level per pixel. The average grey level was calculated for each region of interest. RESULTS: In 32 different conditions, circumflex flow ranged from 0.80 to 12.89 ml.min-1.g-1 and the endocardial/epicardial ratio of flow from 0.53 to 1.73. In the circumflex region (subjected to flow changes) segmental amplitude varied from 76(SD 20) (end diastole) to 56(18) (end systole), p < 0.001. In all regions, a consistent cyclic variation was found, ranging from 9(14) to 28(16)%. For all levels of flow, subendocardial and subepicardial regions showed similar values of both absolute amplitude and cyclic variation. No significant relationship was found between transmural distribution of blood flow and either segmental amplitude (r = 0.26) or cyclic variation (r = 0.04). CONCLUSIONS: (1) a consistent cyclic grey level variation is present in all regions of the canine left ventricle, but subendocardial and subepicardial layers show similar values of both absolute amplitude and cyclic variation; (2) in the absence of severe underperfusion and echocardiographically detectable dyssynergy, absolute amplitude and cyclic variation are totally unrelated to changes in coronary blood flow.

Animals↗
PubMed1993

Left ventricular performance and ultrasonic myocardial quantitative reflectivity in endurance senior athletes: an echocardiographic study.

Young elite athletes often show left ventricular hypertrophy, but normal values of quantitatively evaluated myocardial wall reflectivity. The aim of this study is to assess the acoustic pattern of ventricular wall reflectivity, as well as of systolic and diastolic function, in older endurance runners with increased left ventricular mass. For this purpose, 12 elite, senior isotonic athletes in full training and 11 normal, age-matched controls with sedentary life styles were studied. The following parameters were measured with a commercially available 2D echo-Doppler machine: end-diastolic diameter, diastolic septum thickness, left ventricular mass index, ejection fraction (by Teicholtz rule); peak E, peak A, E/A ratio, acceleration and deceleration time of mitral inflow velocity and isovolumic relaxation time. On-line radio frequency analysis was also performed to obtain quantitative operator-independent measurements of the integrated backscatter signal of the ventricular septum and the posterior wall. The integrated values of the radiofrequency signals were normalized for the pericardial interface and expressed in percent (% 2D-IB). In spite of the greater left ventricular mass in athletes versus normal controls (319 +/- 81 vs 225 +/- 63 g.m-2, P < 0.0005), there were no significant intergroup differences as regards end-diastolic diameter (50.7 +/- 5.1 vs 48.1 +/- 5.2 mm, P = ns), ejection fraction (75.5 +/- 9.3 vs 71.8 +/- 9.1%, P = ns), and 2D-IB of septum (22.2 +/- 6.9 vs 22.4 +/- 7.0, P = ns) and posterior wall (12.5 +/- 5.6 vs 13.1 +/- 2.8, P = ns).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

Efficacy of isosorbide-5-mononitrate versus nifedipine in preventing spontaneous and ergonovine-induced myocardial ischaemia. A double-blind, placebo-controlled study.

This study was designed to assess the efficacy of oral nifedipine as compared to oral isosorbide-5-mononitrate in the prevention of spontaneous and induced vasospastic myocardial ischaemia. Twenty-one patients admitted to the Coronary Care Unit as a result of angina at rest underwent both Holter monitoring and an echo-ergonovine test during placebo and following either isosorbide-5-mononitrate or nifedipine according to a double-blind randomized trial. Both drugs caused a statistically significant reduction in spontaneous (87% and 95%, respectively) and induced ischaemic attacks (66% and 75%, respectively). No significant difference was found between the two drugs.

Administration, Oral↗
PubMed1993

Myocardial washout of sonicated iopamidol does not reflect the transmural distribution of coronary blood flow.

It has been shown in previous studies that myocardial contrast echocardiography provides quantitative information on coronary blood flow. However, the ability of contrast echo to assess the transmural (endo/epicardial) distribution of blood flow is still debated. To test this hypothesis, the left circumflex coronary arteries of six anaesthetized open-chested dogs were cannulated and perfused with blood from the femoral artery. At different rates of coronary blood flow, during adenosine-induced coronary vasodilation, sonicated iopamidol and radionuclide labelled microspheres were injected into the coronary cannula, immediately proximal to a mixing chamber. Two-D echo images were digitized and myocardial time-intensity curves were obtained for the endocardial, mid- and epicardial layers. A good correlation existed between contrast washout of the entire ventricular wall and coronary flow (r = 0.85). However, the washout rate from the endo-, mid- and epicardial layers showed weak correlations with corresponding regional blood flows measured by microspheres (r = 0.56, 0.71 and 0.58, respectively). No significant relationship was found between the endo/epicardial washout ratio and the corresponding flow ratio by microspheres. Thus, measurement of the transmural distribution of coronary blood flow by myocardial contrast echocardiography remains an elusive goal.

Animals↗
PubMed1993

Hyperventilation-echocardiography test for the diagnosis of myocardial ischaemia at rest.

The purpose of this study was to assess the feasibility, safety, specificity and sensitivity of the hyperventilation test performed under echocardiographic monitoring for the provocation of vasospastic ischaemia. Hyperventilation (approximately 30 cycles.min-1 for 5 min) was performed in 104 hospitalized patients, referred for pain typical of angina at rest, under 2-D echocardiographic and 12-lead electrocardiographic monitoring. All the tests were completed and no significant side effect was observed. In-hospital documentation of spontaneous myocardial ischaemia and/or ergonovine-induced ischaemia was achieved in 38 patients (group I). A positive hyperventilation-echocardiography test (occurrence of new transient asynergies or worsening of basal ones) was obtained in 32/38 patients. Among the group I patients, only 23 had diagnostic ST-T changes and only 16 experienced chest pain during the hyperventilation-echo test. Of the 66 patients without evidence of myocardial ischaemia at rest (negative ECG monitoring during hospitalization and/or negative ergonovine maleate-echo test)--Group II, none showed echocardiographic changes, seven presented ST-T changes and six complained of typical chest pain during the test. Thus, in relation to in-hospital documentation of myocardial ischaemia at rest, both spontaneous and/or ergonovine-induced episodes, the hyperventilation-echo test showed a specificity of 100%, a sensitivity of 84%, a positive predictive value of 100% and a negative predictive value of 92%. In conclusion, hyperventilation performed under echocardiographic monitoring is feasible and safe; it can be proposed as a screening test to unmask vasospastic myocardial ischaemia in patients with angina at rest, in whom documentation of spontaneous episodes is not available.

Adult↗
PubMed1993

Enhanced sensitivity for detection of coronary artery disease by addition of atropine to dipyridamole echocardiography.

Dipyridamole echocardiography test (DET) has gained acceptance due to its safety, feasibility, diagnostic accuracy and prognostic power. The main limitation of the test is a less than ideal sensitivity in some patient subsets, such as those with limited coronary artery disease. Atropine with dipyridamole might theoretically combine to become a synergistic ischaemic stress test, by increasing myocardial oxygen demand through chronotropic stress and by reducing flow supply through a shortening of the diastolic interval under maximal coronary vasodilation. The aim of this study was to assess the effects of the addition of atropine to DET. Three hundred and twenty-one patients (age = 58 +/- 9 years), referred for testing in the echo lab, were initially studied by DET. Of these, 151 were stopped during or within the 2 min following dipyridamole infusion because of achievement of a predetermined end-point: obvious echocardiographic positivity (n = 137), severe chest pain (n = 3), diagnostic ST segment changes (n = 7) or limited side effects (n = 4). In another three cases, atropine was not given due to a history of glaucoma or severe prostatic hypertrophy. In the remaining 167 patients with a negative DET test, atropine (0.25 mg intravenously, repeated every min up to a maximum of 1 mg, if necessary) was added, starting 3 min after the end of the dipyridamole infusion. The dipyridamole-atropine echo test (DETA) was positive in 32 and negative in 135 patients, and no major side effects occurred in any patient.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Quantitative ultrasonic analysis of myocardium in patients with thalassemia major and iron overload.

BACKGROUND: Patients with beta-thalassemia major present with severe anemia and need continuous transfusion therapy. The consequent iron overload leads to hemochromatosis. Initial cardiac dysfunction has been documented even in thalassemics without clinical manifestations of heart failure as well as by conventional echocardiographic-Doppler techniques. The purpose of this study was to assess the acoustic quantitative properties of myocardium in patients with iron overload. METHODS AND RESULTS: Thirty-eight patients with beta-thalassemia major, without clinical signs of cardiac failure, and 20 age- and sex-matched young controls were studied by echocardiography. An on-line analysis of the ultrasonic radiofrequency signal was performed to obtain quantitative operator-independent measurements of the integrated backscatter (IB) signal of the ventricular septum and the posterior wall. The integrated values of the radiofrequency signal were normalized for the pericardial interface and expressed in percent (IB%). Thalassemic patients had been receiving transfusion therapy for 16 +/- 5 years and had received 313 +/- 138 transfusion units; they all had received chelation treatment (desferroxiamine) for 9 +/- 2 years. Patients and controls showed comparable values of echocardiographically assessed percent fractional shortening (32 +/- 3% versus 36 +/- 4%, p = NS), whereas thalassemics showed higher values of left ventricular mass index (118 +/- 30 versus 98 +/- 15 g/m2, p < 0.05). The IB% values were higher in patients with thalassemia major than in controls for both septum (35 +/- 14% versus 21 +/- 6%, p < 0.001) and posterior wall (16 +/- 6% versus 11 +/- 3%, p < 0.001). In thalassemic patients, no significant correlation was found between the septum IB% value and hematological parameters, such as the total number of transfusions (r = 0.2, p = NS) or the mean ferritin value (r = 0.1, p = NS). No significant correlation was also found between the septum IB% value and the echocardiographically assessed left ventricular mass index (r = 0.2, p = NS). CONCLUSIONS: These data demonstrate that myocardial reflectivity is abnormally increased in patients with thalassemia major under transfusion treatment, probably due to myocardial iron deposits and/or secondary structural changes. These quantitatively assessed abnormalities in regional reflectivity can be detected when conventional echocardiographic parameters of systolic left ventricular function are undistinguishable from normal controls.

Adolescent↗