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Biomedical subjects

S Iliceto

Publications and source records attributed to S Iliceto.

At least 91 records · Page 5Linked to original sources
PubMed1991

Echo-Doppler evaluation of the effects of heart rate increments on left atrial pump function in normal human subjects.

It is commonly believed that the atrial contribution to left ventricular filling increases during heart rate increments. However, the relative contribution of the pump function (atrial systole) and of the passive role (diastasis and reservoir) of the atrium to end-diastolic left ventricular filling is not well known. In order to investigate this problem, we performed a two-dimensional echo-Doppler study during right atrial pacing. Transmitral flow velocity curves were obtained by means of pulsed Doppler. Pacing was performed (1) at the lowest heart rate at which it was possible to obtain a stable capture of the atria, (2) at the heart rate at which the early and late Doppler filling waves almost completely overlapped. In both stages pacing was interrupted for a few seconds to obtain some post-pacing beats. Doppler tracing recorded at rest, during pacing and in the immediate post-pacing beats were analysed to obtain well-known parameters of atrial contribution; atrial peak flow velocity, early to atrial peak flow velocity ratio, and time-velocity integral of the atrial wave. Furthermore, in order to distinguish end-diastolic passive flow from the active contribution of atrial systole to filling, we superimposed the envelope of the last Doppler curve obtained during atrial pacing over the envelope of the first post-pacing curve. In this way the area of the atrial wave of the paced beat was divided by the mid-diastolic part of the post-pacing one into two areas, the integrals of which correspond to the active and passive atrial contribution respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

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

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

Blood Flow Velocity↗
PubMed1991

[The vascular aging process: the potentials of intravascular echography].

Intravascular ultrasonography is a new diagnostic technique, based on the utilization of very small ultrasonic transducers, with high emission frequency (20-30 MHz) that can be introduced in cardiac cavities as well as in arterial vessels. Because of its technological characteristics this technique has a great potential for the evaluation of the morphological and functional alterations usually involving the arterial wall as a consequence of ageing. Intimal thickening, medial intimalization, reduced systolic-diastolic excursion of the vessel walls affected by ageing as well as by arterial diseases can be easily identified.

Aging↗
PubMed1990

Prediction of cardiac events after uncomplicated myocardial infarction by cross-sectional echocardiography during transesophageal atrial pacing.

Atrial pacing can safely be utilized shortly after myocardial infarction. To evaluate the prognostic value of wall motion abnormalities induced by such pacing 83 consecutive patients with recent uncomplicated myocardial infarction underwent transthoracic cross-sectional echocardiography during transesophageal atrial pacing and upright bicycle exercise stress test. Patients were followed-up for 14 +/- 5 months. During the atrial pacing and the echocardiography, patients were defined at high risk if abnormalities of wall motion were detected in left ventricular regions remote from the infarcted area. Then, during the exercise stress test, high risk patients were those with ST segment depression greater than or equal to 1 mm. On the other hand, patients were considered to be at low risk if they had no abnormalities of wall motion during atrial pacing in remote regions or, in the case of the stress test, if they did not develop ST depression greater than or equal to 1 mm. Of the 83 patients, 21 had major cardiac events during the period of follow-up. Cardiac events occurred in 15/23 (65%) and 5/60 (8%, P less than 0.001) patients assigned to the groups adjudged to be at high and low risk, respectively, on the basis of echocardiographic results. Exercise testing was less reliable in identifying patients at risk of future cardiac events. Major events occurred in only 6 of the 19 patients with a positive stress test (32%, P less than 0.05 vs positive stress echocardiography) and in 14 of the 64 patients with a negative exercise stress test (22%, P = NS vs positive exercise stress test, P less than 0.05 vs negative atrial pacing echocardiography).

Cardiac Pacing, Artificial↗
PubMed1990

The nature and evolution of ventricular arrhythmias in acute myocardial infarction.

The natural evolution of ventricular arrhythmias complicating a first episode of acute myocardial infarction has been studied in a group of 56 consecutive patients, who were admitted to the Coronary Care Unit within three hours of the onset of symptoms, and in whom drug administration (digitalis, antiarrhythmics, diuretics and heparin) was limited. Ventricular arrhythmias have been evaluated by means of Holter monitoring performed during the first 24 hours, the second 24 hours, the eighth day, the 18th day and two years after discharge when antiarrhythmic drugs has been discontinued for at least five half-lives. The overall incidence and prevalence of ventricular arrhythmias showed a steady and statistically significant reduction from the first to the eighth day, and a not statistically significant increase from the eighth to the 18th day. The latter increase was still present at the two-year follow-up. The one-by-one behaviour analysis of discharged patients delineated three different patterns: patients who presented a steady reduction in ventricular arrhythmias from the first to the 18th day (44%); patients who showed an almost constant incidence of ventricular arrhythmias during all phases of acute myocardial infarction (24%); and patients who presented both a decrease and an increase in their ventricular arrhythmias (31%). The follow-up at two years showed that the majority of patients, especially those discharged in a high Lown class, had the same arrhythmias as at their follow-up on the 18th day. Correlation of ventricular arrhythmias with the extent of the infarcted area demonstrated that only the peak and mean values of lactic dehydrogenase correlated with the severity of ventricular arrhythmias.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1990

Errors in measurements of stroke volume for invasive and echo-Doppler evaluations of valvular regurgitant fractions. Clinical evaluation and computer simulation.

The aim of this study was to compare cardiac catheterization (CATH) with 2D echo-Doppler (ED) in clinically evaluating the stroke volumes (SV) needed to calculate aortic and mitral regurgitant fractions (aortic and mitral SV for the ED method, thermodilution and angiographic SV for the CATH). As there is no 'gold standard' for this kind of measurement, only subjects without valvular regurgitation were considered. In these subjects, though the two SV measurements needed to calculate the regurgitant volume should have been identical, there was, in fact a difference due to the systematic and random errors of the methods. We calculated the mean value and the standard deviation of this difference in a series of patients without valvular regurgitation in order to obtain an estimate of both systematic and random errors. In 20 patients studied by ED a difference of 11.9 +/- 16.7 ml was found. In 36 patients studied by cardiac catheterization the difference was 19.6 +/- 20.1 ml. A significant systematic error was found for both ED and the invasive method; The transmitral SV tended to be larger than the aortic and the angiographic SV larger than that obtained by thermodilution. To try to determine the extent to which the random errors could be attributed to the reproducibility of the measurements, we carried out computer simulations. The SVs of 50 000 hypothetical patients were randomly generated and then attributed a random error calculated on the basis of the variability of the CATH (thermodilution 4%, angiography 10%) and the ED measurements (aortic annulus 6%, mitral annulus 18%, mitral time velocity integral 10%, aortic time velocity integral 8%).(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗
PubMed1990

Evaluation of the effects of gallopamil in patients with effort angina by transesophageal atrial pacing two-dimensional echocardiography.

Transesophageal atrial pacing (TAP) 2D echocardiography was performed after placebo (P) and gallopamil (G) (0.03 mg/kg iv) in 12 patients with stable, reproducible, effort angina. If compared to P study, during G the following changes were observed: 3 out of the 12 patients did not experience angina, time to ST-1mm increased from 5.3 +/- 1.3 to 6.6 +/- 1.6 min (p less than 0.05), wall motion score was improved both at 130 b/min (15.3 +/- 4.1 drug P, 17 +/- 4.8 drug G, p less than 0.01) and at 150 b/min (10.9 +/- 5.7 drug P, 12.8 +/- 6.3 drug G, p = 0.07). In conclusion, gallopamil has a beneficial effect on atrial pacing induced ischemia: it increases pacing time to ischemic threshold and reduces during ischemia the extent of dysfunctional myocardium.

Aged↗
PubMed1990

[Evaluation of coronary anatomy and coronary circulation by transesophageal echocardiography].

UNLABELLED: Nowadays the anatomy and coronary flow can be evaluated by means of various methods requiring cardiac catheterization. Transesophageal echocardiography is a new diagnostic method with great potential (excellent technical quality, stable positioning of the transducer, no lung interposition). Because of its potential we have used transesophageal echocardiography on a number of patients undergoing coronary angiography in order to investigate its reliability in estimating the anatomy and coronary flow. From the anatomical point of view 3 aspects were identified: absence of alterations affecting the vessel being explored (Criterion A); presence of non-stenotic calcific wall plaques (Criterion B); presence of stenotic calcific plaques (Criterion C). The percentage of visualization of the left main artery, the left anterior descending and the circumflex was 87%, 78% and 76% respectively. The criteria described showed varying reliability depending on the coronary portion being considered. Using the pulsed Doppler, during the transesophageal study, we obtained an adequate recording of the velocity profile of the left anterior descending in 28/37 patients. After dipyridamole infusion all velocity parameters (diastolic and systolic mean and maximum velocities) increased significantly in those patients with left anterior descending without stenosis, while remaining practically constant in those patients with significant stenosis of the left anterior descending artery. In particular the ratio between the maximum diastolic velocity recorded after dipyridamole and the velocity recorded immediately before infusion was significantly greater in those subjects with normal left anterior descending than in those with significant stenosis of the left anterior descending artery. CONCLUSIONS: transesophageal echocardiography offers new prospects in studying anatomic alterations and flow patterns of the proximal part of the left coronary artery.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗
PubMed1989

Echo Doppler evaluation of right ventricular dysplasia.

Two-dimensional echocardiography (2D echo) and Doppler were performed in a group of patients who had a high probability of having right ventricular (RV) dysplasia (left bundle branch block arrhythmias, no signs of cardiopulmonary diseases) and in a group of age-matched normals. 2D echo showed RV morphofunctional abnormalities (free wall and apical irregularities, wall motion abnormalities) in 25% of patients with suspected RV dysplasia but in none of the normals. Concordance with angiography was good (75% of cases with positive 2D echo study had a positive angiography, while only 33% of the patients with suspected RV dysplasia and negative 2D echo had a positive angiography). In patients with high probability of RV dysplasia (positive 2D echo and angiography) left ventricular filling was similar to that of normal subjects whereas RV filling was markedly rearranged, as demonstrated by the significant decrease in RV early-to-atrial peak flow velocities.

Adolescent↗
PubMed1988

Effects of acute intrathoracic pressure changes on left ventricular geometry and filling.

Acute changes in intrathoracic pressure (ITP) affect left ventricular (LV) function. It has been suggested that this functional impairment could be the result of an alteration in LV filling caused by a reduction in LV compliance induced by the rearrangement of biventricular geometry that occurs under these conditions. Therefore, to evaluate the effects of an acute increase or decrease in ITP on LV geometry and filling, we used two-dimensional and Doppler echocardiography to study 25 normal volunteers both during the Müller maneuver (acute decrease in ITP induced by a forced inspiration against a closed airway) and during continuous positive airway pressure breathing. During both maneuvers LV geometry was altered as demonstrated by the significant increase in the normalized curvature radius of the interventricular septum and the unchanged curvature radius of the LV free wall. LV filling was altered during both maneuvers as demonstrated by significant decreases in early peak flow velocity, early-to-late peak flow velocity ratio, and early deceleration rate. Thus, during maneuvers that acutely decrease or increase ITP, alterations in LV geometry occur. These acute distortions of LV geometry may be one of the mechanisms responsible for alterations in LV filling.

Adult↗
PubMed1988

Doppler echocardiographic evaluation of the effect of atrial pacing-induced ischemia on left ventricular filling in patients with coronary artery disease.

Very little is known about the effects of acute myocardial ischemia on left ventricular filling. Previous studies of these effects have been of limited value because they were performed with 1) imaging techniques that, like cineventriculography or radionuclide ventriculography, do not allow beat to beat monitoring of left ventricular filling throughout the entire ischemic attack; and 2) exercise, which, even if effective in inducing myocardial ischemia in patients with coronary artery disease, also considerably shortens cycle length, thus leading to additional nonischemic filling alterations. To overcome these limitations, left ventricular filling was studied by means of Doppler echocardiographic evaluation of transmitral flow velocities before and immediately after rapid atrial pacing in 17 patients. Eight patients had coronary artery disease but did not develop ischemia (ST depression greater than or equal to 1.5 mm) during atrial pacing (Group 1) whereas nine had coronary artery disease and developed ischemia during atrial pacing (Group 2). No differences were observed from rest to postpacing in any of the filling variables considered in Group 1 patients. In contrast, a significant rearrangement of left ventricular filling occurred during ischemia in Group 2 patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗