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Biomedical subjects

C Di Mario

Publications and source records attributed to C Di Mario.

At least 163 records · Page 9Linked to original sources
PubMed1993

Dobutamine stress--Doppler echocardiography before and after coronary angioplasty.

To determine if dobutamine-induced myocardial ischaemia causes abnormalities in Doppler parameters of left ventricular ejection and filling and to assess early effects of successful coronary angioplasty (PTCA) on these parameters, dobutamine stress echocardiography and Doppler studies were performed once in 11 normal volunteers and twice in 17 patients (within 1 day pre- and post-PTCA). Dobutamine induced wall motion abnormalities, ST changes and angina in 11, five and five patients, respectively, before and three, two and one patients, respectively, after PTCA. Doppler indices of both systolic and diastolic function were comparable at rest, before and after PTCA. Dobutamine induced similar increases in peak aortic velocity and average acceleration in healthy individuals (39% and 53%) and in patients with one-vessel disease both before (38% and 39%) and after PTCA (39% and 40%). In the three patients with multivessel disease, peak aortic velocity showed a blunted response (-0.3%) before PTCA but increased by 17% after PTCA, while acceleration decreased both before (12%) and after PTCA (14%). There were significant differences (P < 0.0001) between healthy individuals and pre-PTCA patients in the effect of dobutamine on peak early (E) filling velocity (+34% vs -19%), E-acceleration (+35% vs -26%), peak early to atrial filling velocity ratio (E/A) (-0.7% vs -37%) and diastolic time velocity integral (TVI) (+34% vs -22%). After PTCA, the response of Doppler diastolic indices improved during dobutamine, as shown by the increase in E and E-acceleration (+8%, +24%), respectively) and by the decline in the reduction of E/A and TVI (-17% and -10%, respectively). Thus, the response of Doppler diastolic parameters to dobutamine stress is a sensitive indicator of significant coronary disease and is superior to changes in ejection indices. Successful PTCA resulted in an improved diastolic filling response to dobutamine stress.

Adult↗
PubMed1993

[Instantaneous pressure-velocity relationship of the coronary flow, alternative to coronary reserve measurement: a feasibility study and reproducibility of the method].

Animal experimentation has shown that the instantaneous pressure-velocity of coronary blood flow in the hyperaemic phase has a linear relationship. The slope of this regression evaluates coronary reserve independently of haemodynamic variables and the X-intercept (zero flow pressure or Pf = 0) determines the intra-myocardial back pressure which could influence the regulation of coronary flow. The object of this study was to evaluate the instantaneous pressure-velocity relationship of coronary flow in clinical practice and to analyse the reproducibility of this parameter. Forty-nine patients were divided into two groups, depending on whether their coronary arteries were angiographically normal (n = 34) or atheromatous with stenosis > or = 35% of the reference diameter (n = 15). Recordings of coronary flow velocity were made with a Doppler transducer mounted on a 0.018 inch guide wire. The slope of the diastolic linear segment of the pressure-velocity relationship was determined at the peak of papaverine-induced vasodilation from 4 consecutive cycles by a regression analysis. The pressure value at 0 flow was obtained by extrapolation of the regression slope to the axis of aortic perfusion pressure. A good quality spectral recording allowing reliable analysis of the velocity profile was obtained in 88% of cases (44/49). The high values of the correlation coefficient observed with each measurement of the slope confirm the applicability of linear regression analysis to the pressure-velocity relationship. The slope of the pressure-velocity relationship was significantly lower in patients with coronary stenosis (1.7 +/- 0.7 cm/s/mmHg in normal vessels versus 0.7 +/- 0.3 cm/s/mmHg in stenotic arteries, p < 10(-4)), and, similarly, the pressure at zero flow was also reduced (36.9 +/- 16 mmHg versus 25.5 +/- 12 mmHg, p = 0.03). A statistically significant correlation was observed between the slope values and coronary flow reserve but no correlation was demonstrated between the slope and intraluminal surface area of angiographically normal coronary arteries or the slope and degree of stenosis of atheromatous vessels. The linear regression slope and the pressure at zero flow were lower when the pressure-velocity relationship was measured during long diastolic periods induced by the injection of adenosine. In addition, the curvilinear appearances of the pressure-velocity relationship observed during these long periods suggest that the linear regression model is not applicable throughout the whole range of pressures and velocities, especially for the lowest values.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1993

[Doppler microprobe allows evaluation of local coronary circulation].

The local coronary flow in 42 patients (mean age: 59 +/- 9 years) with ischemic heart disease was assessed by means of an 0.018" intracoronary Doppler guidewire. Study population was divided into two groups: group I--"normal vessels" (diameter stenosis < 30%) and group II--"stenosis vessels" (diameter stenosis > 60%). Measurements of: averaged peak velocity (APV), diastolic-systolic velocity ratio (DSVR) were performed in proximal segments of normal vessels and proximally to stenosis in group II. APV and DSVR were recorded at rest (bas) and during papaverine induced hyperemia. Coronary flow reserve (CFR) was calculated as ratio hyperemic and resting values of APV. Mean value of APV at rest was highest for left main stem, lowest for venous by-passes (SVBG) but did not differ among three coronary arteries (LAD, LCX, RCA). CFR value was significantly higher for group I then for group II (2.75-3.3 vs 1.8-2.0) but did not differ significantly among particular arteries in both groups. Mean value of DSVRbas in both examined groups was lowest for right coronary artery and for SVBG (ca. 1.0) and did not change significantly during hyperemia. This value was significantly higher (ca. 2.0) for left coronary arteries (LAD, LCX) then for RCA and SVBG and significantly decreased after administration of papaverine.

Aged↗
PubMed1993

[Doppler microprobe for evaluation of coronary circulation after successful coronary angioplasty].

The influence of angiographically successful coronary angioplasty (PTCA) in 27 patients (mean age 64 +/- 8 years) was assessed by means of 0.018" intracoronary Doppler guidewire. Averaged peak flow velocity (APV) and diastolic-systolic velocity ratio (DSVR) were recorded in resting conditions (bas) and during papaverine induced hyperemia before and after PTCA. Coronary flow reserve (CFR) was calculated as ratio of hyperemic and resting APV. The parameters mentioned above were estimated proximally and distally to coronary stenosis to be dilated. Mean value of APVbas for distal part of the vessels was significantly lower (about 46-57%) then for the two proximal segments. PTCA caused significant increase of APVbas as for proximal (about 21-69%) as for distal segments (about 62-77%). That procedure caused significant increase of CFR only for right coronary artery (RCA). Mean values of DSVRbas in proximal position for left descendens (LAD) and left circumflex (LCx) arteries before PTCA were significantly higher than DSVbas for distal position but did not differ for RCA. PTCA caused significant increase of DSVRbas in distal position only for LAD and LCx. Our results showed that angiographically successful PTCA causes significant increase of APVbas for right and left coronary arteries and normalization of DSVRbas in distal segments of LAD and LCx.

Adult↗
PubMed1992

In-vivo validation of on-line and off-line geometric coronary measurements using insertion of stenosis phantoms in porcine coronary arteries.

Geometric coronary artery measurements with the Phillips Digital Cardiac Imaging System (DCI) and the Cardiovascular Angiography Analysis System (CAAS) were validated using percutaneous insertion of radiolucent stenosis phantoms in swine coronary arteries. Angiographic visualization of the stenosis lumens (phi 0.5, 0.7, 1.0, 1.4, 1.9 mm) was simultaneously recorded on DCI and cinefilm. The acquisition systems were calibrated by either the diameter of the guiding catheter (catheter CAL) or the isocenter method (isocenter CAL). Minimal luminal diameters (MLD) obtained with CAAS and DCI on 20 corresponding cineframes were compared with the true phantom diameters (PD). The accuracy of MLD measurements with the CAAS using isocenter CAL was -0.07mm, the precision 0.21 mm (r = 0.91; y = 0.30 + 0.79x; SEE = 0.19), with catheter CAL the accuracy was 0.09 mm, the precision 0.23 mm (r = 0.89; y = 0.19 + 0.74x; SEE = 0.19). The accuracy of MLD measurements using the DCI with isocenter CAL was 0.08 mm, the precision 0.15 min (r = 0.96; y = 0.08 + 0.86x; SEE = 0.14), with catheter CAL the accuracy was 0.18 mm, the precision 0.21 mm (r = 0.92; y = 0.09 + 0.76x; SEE = 0.17). DCI underestimated PD with isocenter CAL (p less than 0.05) and with catheter CAL (p less than 0.001). MLD can be measured with high accuracy, both applying on-line digital as well as off-line cineangiographic analysis. The results of digital measurements demonstrate high reliability of the new digital software package.

Animals↗
PubMed1992

Edge detection versus densitometry in the quantitative assessment of stenosis phantoms: an in vivo comparison in porcine coronary arteries.

The aim of this study was the in vivo validation and comparison of the geometric and densitometric technique of a computer-assisted automatic quantitative angiographic system (CAAS system). In six Landrace Yorkshire pigs (45 to 55 kg), precision-drilled phantoms with a circular lumen of 0.5, 0.7, 1.0, 1.4, and 1.9 mm were percutaneously introduced into the left anterior descending or left circumflex coronary artery. Twenty-eight coronary angiograms obtained with the phantom in a wedged intracoronary position could be quantitatively analyzed. Minimal lumen diameter, minimal cross-sectional area, percent diameter stenosis, and cross-sectional area stenosis were automatically measured with both the geometric and densitometric technique and were compared with the known phantom dimensions. When minimal lumen diameter was measured using the geometric approach, a nonsignificant underestimation of the phantom size was observed, with a mean difference of -0.06 +/- 0.14 mm. The larger mean difference observed with videodensitometry (-0.11 +/- 0.20 mm) was the result of the failure of the technique to differentiate the low lumen videodensities of two phantoms of smaller size (0.5 and 0.7 mm) from a dense background. Percent cross-sectional area stenosis measured with the two techniques showed a good correlation with the corresponding phantom measurements (mean difference between percent cross-sectional area stenosis calculated from the quantitative angiographic measurements and the corresponding phantom dimensions was equal to 2 +/- 6% for both techniques, correlation coefficient = 0.93 with both techniques, SEE = 5% with the geometric technique and 6% with the densitometric approach).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Histological changes in the aortic valve after balloon dilatation: evidence for a delayed healing process.

OBJECTIVE: To investigate whether balloon dilatation of the aortic valve induces long-term macroscopic or histological changes or both to explain the restenosis process. DESIGN: Prospective study of 39 consecutive patients. Sixteen later (mean (SD) 12 (10) months) required operation. This non-randomised subgroup was compared with 10 patients who had aortic valve replacement without prior dilatation. SETTING: University cardiology and cardiac surgery centre and pathology department. PATIENTS: 16 patients who had aortic valve replacement because of failure of or restenosis after balloon dilatation of the aortic valve. Twelve resected valves were examined. INTERVENTIONS: Percutaneous balloon dilatation of the aortic valve (maximal balloon size: trefoil 3 x 12 mm balloon or bifoil 2 x 19 mm balloon) and surgical inspection before excision of the aortic valve leaflets during open-chest aortic valve replacement. Fixation, decalcification, and staining for histology. MAIN OUTCOME MEASURES: Presence of long-term pathological changes in the resected valve and their relation to restenosis after balloon dilatation. RESULTS: Macroscopically the previously dilated valves were indistinguishable from valves from the patients who had valve replacement only. Microscopically, the dilated aortic valves showed areas of young scar tissue that were not seen in a control group of surgically excised stenotic aortic valves. This persistent scarring reaction was seen around small tears or lacerations of the collagenous valve stroma, fractures in calcified areas, and splits in commissures. Young scar tissue without collagenisation was still present 24 months after dilatation. CONCLUSION: Organisation and collagenisation of scar tissue develops slowly after balloon dilatation of the aortic valve. This prolonged scarring reaction may explain the late development of restenosis in some patients.

Aged↗
PubMed1991

Validation of quantitative analysis of intravascular ultrasound images.

This study investigated the accuracy and reproducibility of a computer-aided method for quantification of intravascular ultrasound. The computer analysis system was developed on an IBM compatible PC/AT equipped with a framegrabber. The quantitative assessment of lumen area, lesion area and percent area obstruction was performed by tracing the boundaries of the free lumen and original lumen. Accuracy of the analysis system was tested in a phantom study. Echographic measurements of lumen and lesion area derived from 16 arterial specimens were compared with data obtained by histology. The differences in lesion area measurements between histology and ultrasound were minimal (mean +/- SD: -0.27 +/- 1.79 mm2, p greater than 0.05). Lumen area measurements from histology were significantly smaller than those with ultrasound due to mechanical deformation of histologic specimens (-5.38 +/- 5.09 mm2, p less than 0.05). For comparison with angiography, 18 ultrasound cross-sections were obtained in vivo from 8 healthy peripheral arteries. Luminal areas obtained by angiography were similar to those by ultrasound (-0.52 +/- 5.15 mm2, p greater than 0.05). Finally, intra- and interobserver variability of our quantitative method was evaluated in measurements of 100 in vivo ultrasound images. The results showed that variations in lumen area measurements were low (5%) whereas variations in lesion area and percent area obstruction were relatively high (13%, 10%, respectively). Results of this study indicate that our quantitative method provides accurate and reproducible measurements of lumen and lesion area. Thus, intravascular ultrasound can be used for clinical investigation, including assessment of vascular stenosis and evaluation of therapeutic intervention.

Angiography↗
PubMed1991

Acute effects of gallopamil on left ventricular systolic and diastolic function in patients with ischaemic heart disease.

In 13 patients with chronic stable angina, left ventricular pressures were measured by catheter-tip micromanometer, and left cineventriculography was performed at matched atrial paced rates before and 20 min after administration of intravenous gallopamil (3 mg). Mean plasma concentration of gallopamil at the second haemodynamic and angiographic assessment was 18.6 +/- 5.7 ng.ml-1. Left ventricular peak systolic pressure decreased from 134 +/- 12 to 125 +/- 13 mmHg (P less than 0.005) and mean aortic pressure from 94 +/- 11 to 91 +/- 9 mmHg (ns). Peak positive first derivative of left ventricular pressure (+dP/dt) and maximal velocity of the contractile element (Vcemax) significantly decreased (from 1828 +/- 334 to 1702 +/- 304 mmHg.s-1, P less than 0.002, and from 51 +/- 11 to 43 +/- 5 s-1, P less than 0.001, respectively). Left ventricular protodiastolic pressure decreased from -0.6 +/- 2.9 to -2.8 +/- 2.9 mmHg (P less than 0.005) and left ventricular end-diastolic pressure from 9.5 +/- 3.4 to 8.9 +/- 4.6 mmHg (ns). No changes occurred in peak negative dP/dt, while a significant reduction was observed in the exponential time constant of the first 40 ms of isovolumetric relaxation (t-constant decreased from 38 +/- 8 to 34 +/- 7 ms, P less than 0.01). No changes were observed in end-diastolic and end-systolic left ventricular volume indices and ejection fraction. Thus, intravenous gallopamil induced a moderate afterload reduction and a slight negative inotropic effect resulting in a net effect of unchanged left ventricular pump function. The observed improvement of early relaxation seems to be a potentially beneficial effect of gallopamil in patients with coronary artery disease.

Adult↗
PubMed1991

Peak aortic blood acceleration: a possible indicator of initial left ventricular impairment in patients with coronary artery disease.

In 25 patients undergoing diagnostic cardiac catheterization, a catheter-tip electromagnetic velocity transducer was used to evaluate maximum velocity and acceleration of blood in the ascending aorta. All patients underwent a complete haemodynamic evaluation, including high-fidelity recording of intraventricular pressures and calculation of the derived indices, left ventriculography and coronary angiography. Nineteen patients with critical coronary stenoses were divided according to the presence of signs of left ventricular dysfunction, while the control group consisted of six subjects with chest pain, but without cardiac abnormalities detectable by cardiac catheterization. Maximum aortic acceleration was significantly lower in coronary patients (378 +/- 130 vs 562 +/- 82 in the control group P less than 0.01) and also in the selected subgroup of coronary patients with normal haemodynamic and angiographic indices of left ventricular systolic function (310 +/- 102 vs 562 +/- 82, P less than 0.01). No relationship could be observed between maximal blood acceleration and left ventricular peak systolic pressure, +dP/dt, left ventricular end-systolic volume index and ejection fraction. Our results suggest that maximal blood acceleration from the left ventricle may detect an initial myocardial impairment in patients with definite coronary artery disease but with normal conventional indices of left ventricular function. The clinical interest of this index, however, is limited by overlapping values in patients with and without coronary artery disease and the inability of a further separation of ischaemic patients in accordance with the severity of left ventricular impairment and the extension of coronary artery involvement.

Adult↗
PubMed1990

Assessment of the "long sheath" technique for percutaneous aortic balloon valvuloplasty.

A 100 cm-long 16.5 F valvuloplasty catheter introducer was assessed as an adjunct for percutaneous transluminal aortic valvuloplasty (PTAV) via the femoral artery in 31 patients with severe aortic stenosis. Observed improvements in peak systolic gradient (81.6 +/- 29.9 mm Hg vs. 35.5 +/- 16.0 mm Hg, P less than 0.000001) and aortic valve area (0.6 +/- 0.4 cm2 vs. 1.0 +/- 0.6 cm2, P less than 0.00001) were similar to those achieved in a control group (C) of 17 patients in which no femoral sheath was used. However, a shorter procedure duration (211 +/- 81 min vs. 117 +/- 30 min, P less than 0.001) and a reduced rate of vascular complications at the femoral puncture site (41% vs. 6.5%) were observed in patients in whom the long sheath (LS) technique was used. The frequency of other PTAV-related complications was comparable (C = 35%, LS = 29%, P = n.s.). Other technical advantages of this device are: 1) prevention of looping and bending of the balloon catheter in tortuous vessels and easy positioning of the balloon across the aortic orifice provided by the LS trackability, 2) stabilisation of the balloon during inflation, 3) monitoring of supravalvular aortic pressure provided by the side-arm of the LS and reliable measurement of systolic gradient, and 4) the ability to perform aortograms without the need of another catheter in the ascending aorta. Thus, in our experience, the long sheath technique is a valuable adjunct for PTAV.

Aged↗
PubMed1990

Aortic valvuloplasty of calcific aortic stenosis with monofoil and trefoil balloon catheters: practical considerations. An evaluation of balloon design and valvular morphology relationship, derived from experimental and clinicopathological observations.

In order to evaluate the relation between balloon design (monofoil, trefoil) and valvular configuration, experimental aortic valvuloplasty was performed in four post-mortem hearts with calcific aortic stenosis of various morphology. The degree of obstruction of the aortic orifice was assessed by computed axial tomography during inflation of monofoil 15 and 19 mm and trefoil 3 x 12 mm balloon catheters. We also evaluated the hemodynamic repercussion of balloon inflation (fall in systolic aortic pressure) in four elderly patients with acquired aortic stenosis who underwent a percutaneous transluminal aortic balloon valvuloplasty, with stepwise increasing balloon sizes of 15 mm, 19 mm and 3 x 12 mm, as during our in vitro experiments, and who underwent aortic valve replacement later on. In these patients, we correlated the anatomy of the excised aortic valves with the retrospective analysis of aortic pressure curves recorded during previous valvuloplasty procedures. Our experimental and clinicopathological observations showed that the degree of obstruction of the aortic orifice in post-mortem specimens and the tolerance to balloon inflation in live patients are dependent of the valvular configuration. Although trefoil balloons have the theoretical advantage to avoid complete obstruction of the aortic orifice during inflation, we observed that in presence of a tricuspid configuration, they could be potentially more occlusive than monofoil balloons since each of the 3 individual components of the trefoil balloon occupied the intercommissural spaces while inflated. However, they offered more residual free space when inflated in aortic valves with a bicuspid configuration (i.e. congenitally bicuspid valves or tricuspid valves with one fused commissure). In our opinion, these observations are relevant, since degenerative disease of the aortic valve (i.e. tricuspid valve without commissural fusion) is now recognized as the most common etiology of aortic stenosis in the elderly.

Aged↗
PubMed1990

Onset of cardiovascular action after oral ibopamine. Early hemodynamic effects of single and repeated doses in patients with idiopathic dilated myocardiopathy.

The acute effects of ibopamine (active ingredient of Inopamil), an orally active dopaminergic agent, were invasively evaluated in 16 consecutive patients with idiopathic dilated cardiomyopathy (New York Heart Association Functional Class II and III) Single doses of 100 and 200 mg were administered to 7 and 9 patients, respectively, and two repeated doses of 100 mg were studied in 6 patients. In order to assess the onset of cardiovascular effect, control hemodynamic measurements were repeated 5, 10, 15, 20, 30, 60, 120, and 180 min after ibopamine 200 mg. Both the tested doses of ibopamine increased the mean pulmonary arterial pressure and the mean pulmonary wedge pressure, with a maximal effect 15 min after drug ingestion (+ 47.0 and + 65.4% in the 200 mg group, p less than 0.002). Pulmonary pressures returned to baseline or lower values beyond 60 min. Systemic arterial pressure showed a small transient increase (+ 7.9% in the 200 mg group at 15 min), but fell significantly below baseline after 120 min, a larger decrease occurring in the 100 mg group (p less than 0.05). Ibopamine had a slower but more prolonged effect on cardiac output (increase of up to 32.1% at 60 min) and systemic vascular resistances. Repeated doses (100 mg after an 8-h interval) elicited comparable cardiovascular effects. Oral ibopamine caused a significant increase in mean pulmonary arterial and capillary pressures as early as 5 min after drug ingestion, before cardiac output and peripheral vascular resistances were affected. A biphasic hemodynamic response was also observed after single and repeated low (100 mg) doses of ibopamine.

Aged↗