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M Marzilli

Publications and source records attributed to M Marzilli.

At least 37 records · Page 2Linked to original sources
PubMed1998

Impact of chronic patency of infarct-related coronary artery on prevalence of myocardial ischemia during the pharmacologic and exercise stress test.

BACKGROUND: Even late restoration of anterograde coronary flow may have beneficial effects on left ventricular function, electrophysiology, and survival in postinfarction patients. HYPOTHESIS: The patency or occlusion of an infarct-related coronary artery in the chronic phase may also be associated with myocardial ischemia provoked by pharmacologic and physiologic stress tests. METHODS: High-dose dipyridamole echocardiography test (DET) (up to 0.84 mg/kg over 10 min), exercise electrocardiography (EET), and coronary angiographic data in a group of 127 in-hospital patients who had survived an acute myocardial infarction were analyzed. Patients who had only angiographic evidence of infarct-related single artery disease (> or = 50% luminal diameter reduction) and no previous revascularization were enrolled in the study. DET and EET were performed (DET in all, EET in 118 patients) within 5 days before coronary angiography. Fifty-seven patients had total occluded infarct arteries (Group 1) with various degrees of collateral circulation (2.6 +/- 1.1 collateral score, by a 3 grading system), whereas the other 70 patients had patent infarct arteries (Group 2) with significant residual stenoses (82 +/- 13% diameter reduction). RESULTS: The prevalence of rest angina or effort angina and topography of the infarct-related coronary artery did not differ between the two groups (all p = NS). There were more patients with Q wave in Group 1 than in Group 2 (72 vs. 57%, p = 0.08) compared with non-Q wave infarction (Group 1 = 28 vs. Group 2 = 43%, p = 0.08). Ischemia in the infarct-related artery territory detected by DET (defined as new wall motion dyssynergy or marked worsening of resting hypokinesia) was 61% in Group 1 and 41% in Group 2 (p = 0.025). EET was positive in 26 of 54 (48%) Group 1 and in 21 of 64 (33%) Group 2 patients (p = 0.09). CONCLUSIONS: Patients with occluded infarct-related arteries have a higher prevalence of ischemia during DET and EET regardless of the presence of collateral flow. These results suggest that the presence of partial anterograde flow in the prolonged period could have a favorable influence on prevalence of residual ischemia in these patients.

Blood Flow Velocity↗
PubMed1997

Coronary vasoconstriction during myocardial ischemia induced by rises in metabolic demand in patients with coronary artery disease.

BACKGROUND: In patients with coronary artery disease, a maximal vasodilation of the coronary microcirculation is generally assumed to occur during myocardial ischemia induced by rises in metabolic demand. However, vasoconstriction has been documented during severe prolonged ischemia in animals. The aim of this study was to investigate coronary vasomotor tone during pacing-induced ischemia in humans. METHODS AND RESULTS: The study included 11 patients with exercise-induced ischemia and single-vessel disease of the left anterior descending artery and 7 control subjects with normal coronary arteries. Blood flow velocity was monitored with a Doppler catheter in the left anterior descending artery. Coronary resistance index was calculated as the ratio between mean arterial pressure and flow velocity. Measurements were obtained at baseline, after intracoronary adenosine (2 mg), and during maximal atrial pacing in the absence and presence of adenosine. After adenosine administration at rest, coronary resistance decreased more in control subjects than in patients (25 +/- 7% of baseline versus 61 +/- 19%; P < .01). Coronary resistance decreased in all control subjects (P < .01) both at maximal pacing (60 +/- 17% of baseline) and after administration of adenosine during tachycardia (31 +/- 13% of baseline). By contrast, all 10 ischemic patients displayed increased coronary resistance at maximal heart rate (221 +/- 131% of baseline; P < .01 versus baseline, P < .01 versus control subjects). At this stage, adenosine decreased coronary resistance to 44 +/- 20% of values observed before injection. Additionally, it reduced ST-segment depression in 5 of 8 patients. CONCLUSIONS: In patients with coronary artery disease, transient myocardial ischemia induced by increased metabolic demand is not associated with maximal vasodilation. Rather, an inappropriate severe microvascular vasoconstriction is present that can be abolished by intracoronary adenosine.

Adenosine↗
PubMed1997

Assessment of coronary reserve by transoesophageal Doppler echocardiography. Direct comparison between different modalities of dipyridamole and adenosine administration.

BACKGROUND: This study was undertaken to compare the coronary vasodilator response to different application modalities of intravenous vasodilators, in order to identify the optimal pharmacological protocol for the evaluation of coronary reserve by means of transoesophageal Doppler echocardiography. METHODS: Blood flow velocity in the left anterior descending artery, coronary vascular resistance and left main coronary artery cross-sectional area were assessed by transoesophageal echo-Doppler during an i.v. adenosine bolus (5 mg), a 5-min adenosine infusion (infusion rate 140 micrograms. kg-1 min-1), and low (0.56 mg.kg-1. 4 min-1), and high-dose (0.84 mg.kg-1.9 min-1) dipyridamole infusions in 10 healthy normals (Group 1) and in 20 patients (Group 2) with either coronary microvascular disease (11 patients) or coronary artery disease (nine patients). RESULTS: In both groups, the highest flow velocity and the lowest coronary vascular resistance were observed during the adenosine infusion. Flow velocity values and indices of coronary vasodilator capacity observed after the adenosine bolus and the high-dose dipyridamole infusion were very close to those obtained during the adenosine infusion, especially in Group 1. Coronary flow velocity was lower and coronary vascular resistance higher after low-dose dipyridamole, significantly in Group 2. The maximal flow response to the adenosine bolus was observed within a few seconds after the injection, and was very short. The peak response to the adenosine infusion was observed 57 +/- 27 s after its start. The coronary flow velocity response to dipyridamole was dose dependent and differed between Groups 1 and 2. CONCLUSION: In combination with transoesophageal Doppler echocardiography, a short-lasting adenosine infusion at a rate of 140 micrograms.kg-1.min-1 seems to be preferable to an adenosine bolus and dipyridamole infusion. The effect of the bolus is too short for an accurate measurement of coronary flow velocity, while the dipyridamole infusion, especially at a low dose, induces a submaximal vasodilator response.

Adenosine↗
PubMed1997

Impact of culprit lesion morphology on prevalence of provoked myocardial ischaemia in patients with old myocardial infarction. A dipyridamole stress echocardiography, exercise electrocardiography and angiographic study.

We have recently shown that in patients with single vessel disease and no myocardial infarction, a complex plaque morphology makes myocardium more vulnerable to ischaemia during dipyridamole echocardiography testing. Whether coronary lesion morphology in the infarct-related artery in a chronic phase may also modulate prevalence of ischaemia in the same territory remains unknown. In order to determine the possible relationship between culprit lesion morphology in the infarct-related artery and the prevalence of homotopic ischaemia during stress tests, data from high dose dipyridamole echocardiography tests (up to 0.84 mg.kg-1 over 10 min), exercise electrocardiography and coronary angiography from 73 in-hospital patients with a previous myocardial infarction and patent infarct-related single-vessel disease (> or = 50% diameter reduction) were analysed. An angiographic culprit lesion was considered complex (Ambrose classification) when irregular borders, ulcers, thrombus and/or intraluminal lucencies were present. According to angiographic lesion morphology, two groups were identified: Group I, with simple-type culprit lesions; Group II, with complex type culprit lesions. Number of patients (I = 36; II = 37), age (I = 57 +/- II vs II = 55 +/- 9 years), ejection fraction (I = 58.8 +/- II 3 vs II = 56.5 +/- 10.2%), number of Q or non-Q wave myocardial infarctions, prevalence of rest angina (I = 9; II = II) or effort angina (I = 10; II = 10), culprit lesion stenosis severity (I = 57.9 +/- 7.2% vs II = 57.7 +/- 6.2% by computer analysis) and degree of infarct artery anterograde flow (I = 2.64 +/- 0.48 vs II = 2.56 +/- 0.50 by Thrombolysis in Myocardial Infarction definition) did not differ between the two groups (P = ns for all intergroup differences). Dipyridamole echocardiography test-induced ischaemia (considered as new or worsening abnormal wall motion) in the infarct-related artery territory was 25% in Group I and 59% in Group II (P < 0.01). Among positive dipyridamole echocardiography tests, low dose (0.56 mg.kg-1 over the 4 min) positivity occurred in two out of nine Group I patients and in 16 out of 22 Group II patients (22 vs 73%, P < 0.05). Exercise electrocardiography was positive in seven out of 32 Group I patients, and in 16 out of 35 Group II patients (22 vs 46%, P < 0.05). The peak rate pressure product tended to be higher in Group I than in Group II patients (282 +/- 65 vs 257 +/- 65 mmHg x beats.min x 10(2), P = 0.07). Thus, in patients with previous myocardial infarction and a patent infarct-related artery, complex culprit lesion morphology is associated with a higher prevalence of ischaemia and a lower ischaemic threshold during both exercise and dipyridamole stress testing. The morphology of culprit stenosis is important in modulating different stress responses in the chronic phase of myocardial infarction.

Adult↗
PubMed1997

Organic coronary stenosis in Prinzmetal's variant angina.

Functional factors are known to precipitate ischemic episodes at rest in variant angina, but the role of fixed coronary lesions is still debated. The prevalence, extent, severity and prognostic implications of organic coronary stenoses in variant angina were evaluated in 162 patients with transient ST segment elevation documented during hospitalization. Seventy-eight patients had normal coronary arteries or single-vessel coronary lesions (group 1) and 84 patients had multivessel coronary stenoses (group 2). Both groups were followed up for 82 +/- 41 months. Angiographically normal coronary arteries were observed in only 11 patients (7%). In 59 patients with single-vessel coronary stenoses, the internal luminal diameter was reduced by 51 +/- 12%. There were 20 deaths (16 from cardiac causes) during the 5-year follow-up. Kaplan-Meier survival analysis revealed a significantly lower 5-year survival rate in group 2 (80.1%) compared to group 1 (94.6%, p = 0.006 by Mantel-Haenszel test). If only cardiac causes of death were considered, the 5-year survival rate was still lower in group 2 (84.0%) than in group 1 (97.1%, p = 0.004). Considering both revascularized patients and those treated medically for the entire duration of the follow-up, the survival rate was significantly lower in group 2 than in group 1. Finally, the extent of coronary lesions was an independent predictor of survival by Cox multivariate regression analysis. Organic coronary stenoses are frequent in patients with variant angina and are important for the long-term prognosis.

Adult↗
PubMed1996

Angiographically assessed coronary collateral circulation increases vulnerability to myocardial ischemia during vasodilator stress testing.

In patients with a major coronary vessel occluded, the presence of good coronary collateral circulation increases vulnerability to myocardial ischemia induced by pharmacologic coronary vasodilation. The presence of good collaterals results in a greater frequency, severity, and extent of dipyridamole-induced regional left ventricular dysfunction, consistent with the hypothesis of angiographically assessed collaterals facilitating "steal phenomena" during dipyridamole-induced coronary vasodilation.

Aged↗
PubMed1996

The atropine factor in pharmacologic stress echocardiography. Echo Persantine (EPIC) and Echo Dobutamine International Cooperative (EDIC) Study Groups.

OBJECTIVES: This study sought to compare, head to head, the two most popular pharmacologic stress echocardiographic tests--dipyridamole and dobutamine--with state of the art protocols in a large multicenter prospective study. BACKGROUND: In the continuing quest for ideal diagnostic accuracy, pharmacologic stress echocardiography has quickly moved over the years from low to high dose regimens and is currently performed with atropine coadministration. METHODS: Dobutamine (up to 40 microgram/kg body weight per min) plus atropine (up to 1 mg over 4 h) and dipyridamole (up to 0.84 mg/kg per min over 10 h) plus atropine (up to 1 mg over 4 h) stress echocardiography was performed on different days, in random order and within 1 week in 360 patients with chest pain syndrome. Thirteen different echocardiographic laboratories, all fulfilling quality control criteria for stress echocardiographic reading, contributed to the study. RESULTS: No major complications occurred during either test. The test was interrupted before achievement of predetermined end points for limiting side effects in 37 dobutamine-atropine and 7 dipyridamole-atropine stress echocardiographic studies (feasibility 90% vs. 98%, p < 0.01). Diagnostic accuracy was assessed in a subset of 110 patients with no obvious rest dyssynergy (akinesia or dyskinesia) who underwent coronary angiography independently of test results and within 1 week of testing. Significant coronary artery disease (> or = 50% diameter reduction in at least one major coronary vessel by quantitative coronary angiography) was found in 92 patients. Sensitivity for detection of coronary artery disease was 84% (77 of 92) for dobutamine-atropine and 82% (75 of 92) for dipyridamole-atropine stress echocardiography (p = NS), with a specificity of 89% (16 of 18) for dobutamine-atropine and 94% (17 of 18) for dipyridamole-atropine stress echocardiography (p = NS). A significant correlation was present between peak wall motion score index during dipyridamole-atropine and dobutamine-atropine stress echocardiography (r = 0.83, p < 0.0001). CONCLUSIONS: Dobutamine-atropine and dipyridamole-atropine stress echocardiography are safe and feasible, although submaximal studies are more frequent with dobutamine. The two stresses have comparable accuracy in the detection of angiographically assessed coronary artery disease, although dobutamine is marginally more sensitive and dipyridamole marginally more specific. Stratification of the ischemic response in the space domain is also comparable with the two stresses.

Angina Pectoris↗
PubMed1996

Quantitative assessment of coronary atherosclerotic plaque profile by morphometric analysis of angiographic images.

Coronary plaque morphology (simple or complex) has a recognized clinical, pathophysiologic, and prognostic importance, but its routine use is hampered by the subjective and qualitative nature of the assessment. The aim of this study was to assess the feasibility and accuracy of mathematical, objective, operator-independent assessment of plaque morphology, by means of algorithms based on vector and fractal analysis, previously developed for describing continuous curves. Twenty coronary angiograms were analyzed: 10 with "simple-type" stenosis (defined according to Ambrose type I pattern, Group I) and 10 with "complex-type" stenosis (Ambrose type II pattern, Group II). Five morphometric parameters effectively separated simple and complex-type stenosis: peaks/cm (Group I = 0.24 +/- 0.31 vs Group II = 2.46 +/- 1.83, P < .01); summed maximum error/cm (I = 0.94 +/- 1.19 vs II = 4.53 +/- 0.56, P < .01); integrated error/cm (I = 0.22 +/- 0.27 vs II = 2.25 +/- 1.68, P < .01); number of features/cm (I = 0.02 +/- 0.05 vs II = 1.19 +/- 0.65, P < .01); standard deviation curvature (I = 0.07 +/- 0.01 vs II = 0.22 +/- 0.21, P = 0.06). The scaled edge-length ratio-the only parameter based on fractal analysis-was not different between the two groups (I = 1.03 +/- 0.01 vs II = 1.13 +/- 0.10, P = ns). Hence, a quantitative description of plaque morphology is feasible and allows an effective discrimination of simple and complex plaque profiles with morphometric parameters based on vector analysis.

Coronary Angiography↗
PubMed1996

[Quantitative evaluation of the dynamics of the coronary wall in man: description of a new method based on tridimensional time-dependent reconstruction of intravascular ultrasonographic images].

BACKGROUND: Intravascular ultrasound imaging provides information on vascular lumen and arterial wall structure and it has potential application in arterial wall dynamic study. The aim of this study was to develop a computer assisted system for analysing digitised cross sectional ultrasound images of coronaries to easily display and quantify coronary dynamic and its relationship with arterial wall morphology. METHODS AND RESULTS: To extract the anatomical regions of interest from the digitised sonograms, automatic image segmentation and interactive procedures for manual correction were implemented. This step included the recognition of the lumen edge and an analysis of gray level intensity of the wall. Subsequently, a virtual 3D reconstruction of lumen and vessel wall was done in a Cartesian system where the XY plane was parallel to each cross-sectional sonogram, while the Z axis corresponded to the acquisition time. The baricentre of vascular lumen was used as a reference for alignment. We obtained a cylinder-like solid representing the behavior of the arterial cross-sectional sonogram in time, with the possibility to look either at the wall or at the lumen. In this virtual solid it was possible to measure the variation of lumen area and of 16 hemidiameters; in addition, the derivatives of these values, allowing an estimate of the velocity of events, can be obtained. CONCLUSIONS: The described computerised system for the analysis of intravascular ultrasound images could become a very useful tool for 3D representation and quantitative monitoring of coronary compliance and their relationship with segmental arterial wall morphology.

Coronary Vessels↗
PubMed1996

Adenosine-induced renal vasoconstriction in man.

OBJECTIVE: The aim of the study was to evaluate the effects of adenosine on renal blood flow in humans. METHODS: Eleven normotensive patients (mean age 53 +/- 11 years) with normal renal angiograms were enrolled in the study. Arterial blood pressure, one ECG lead and arterial renal blood flow velocity, by intravascular Doppler catheter, were monitored throughout the procedure. Incremental doses (10(-5), 10(-4), 10(-3), 2 x 10(-3), 5 x 10(-3), 10(-2), 10(-1), 1 mg) were selectively injected, at 5-min intervals, in a renal artery. RESULTS: Adenosine administration had no significant effects on blood pressure, heart rate and atrio-ventricular conduction. A progressive reduction in renal blood flow velocity (from 16.36 +/- 1.9 to 3.9 +/- 0.8 cm/s, P < 0.0001) was observed. Following adenosine the decrease of flow velocity was immediate and its duration was proportional to dosage (from 0.5 +/- 0.4 s at 10(-5) mg to 31 +/- 6.5 s at 1 mg). Renal angiography, repeated in four patients during flow velocity decrement, showed no changes in vessel diameter. CONCLUSIONS: Exogenous adenosine-induced a marked and transient reduction in renal blood flow in man. This effect suggests that adenosine or its metabolites may be directly implicated in rapid and powerful mechanisms of cardiac output redistribution. Thus endogenous adenosine could have a role in regulating renal blood flow in physiological and pathological situations like strenuous exercise, hemorrhage shock and cardiac failure.

Adenosine↗
PubMed1995

Complex coronary artery lesion morphology influences results of stress echocardiography.

BACKGROUND: The likelihood of a positive response with dipyridamole stress echocardiography (DSE) is directly related to the extent and severity of angiographically assessed coronary artery disease. Whether coronary lesion morphology--a known predictor of adverse cardiac events--may also modulate stress echo results remains unknown. The objective of our study was to assess the relation between stenosis lesion morphology and stress echocardiographic results. METHODS AND RESULTS: High-dose (up to 0.84 mg/kg over 10 minutes) DSE and coronary angiographic data of 68 in-hospital patients (39 with stable angina, 29 with angina at rest) with nonoccluding, single-vessel disease at angiography and no previous myocardial infarction were analyzed. DSE was performed in all patients within 3 days of coronary angiography. An angiographic lesion was considered complex when irregular borders and/or intraluminal lucencies suggestive of ulcer and/or thrombus were present. According to angiographic lesion morphology, two groups were identified: group 1, with simple coronary lesions, and group 2, with complex coronary lesions. The two groups were matched for number of patients (n = 34 in each group), age (group 1, 59 +/- 9 versus group 2, 59 +/- 10 years, P = NS), and coronary artery stenosis severity by quantitative coronary angiography (group 1, 60 +/- 7% versus group 2, 58 +/- 6% diameter reduction, P = NS). The sensitivity of DSE was lower in patients of group 1 when compared with group 2 (53% versus 85%, P < .001). Among positive DSE, the low-dose (0.56 mg/kg over 4 minutes) positivity was less frequent in group 1 than in group 2 patients (17% versus 62%, P < .01). Exercise ECG was completed in 66 patients, and it was positive (> .1 mV ST-segment shift from baseline) in 20 out of 33 group 1 and in 22 out of 33 group 2 patients (61% versus 67%, P = NS). The peak rate-pressure product tended to be higher in group 1 than in group 2 patients (257 +/- 52 versus 240 +/- 64 mm Hg x beats per minute x 10(2), P = NS). CONCLUSIONS: In patients with single-vessel disease without coronary occlusion or previous myocardial infarction, coronary lesion morphology of the complex type is associated with a higher DSE sensitivity and with a greater prevalence of low-dose, positive responses. Presence of irregular plaque contours, not only plaque geometry, is important in modulating stress responses in the presence of angiographically assessed coronary artery disease.

Aged↗
PubMed1995

From the experimental myocardial infarction to the clinical acute myocardial infarction: limitations of thrombolytic therapy.

Early administration of thrombolytic agents in acute myocardial infarction lowers mortality and preserves left ventricular function. Currently, only one third of infarct patients receive this treatment, the vast majority being excluded because of restrictive criteria and delayed hospital admission. When correctly administered, thrombolytic therapy achieves reperfusion in 50-85% of occluded vessels. Five to 15% of these initially recanalized vessels eventually reocclude. Possible mechanisms of failure of thrombolytic therapy to induce stable coronary reperfusion include thrombus formation during thrombolysis, platelet activation by thrombolysis, fibrin deposition during thrombolysis, and resistance to thrombolysis. Bleeding complications including intracranial haemorrhage remain a major complication. New therapeutic regimens, new thrombolytic agents and more effective anti-thrombotic drugs, together with intervention strategies that anticipate the time of treatment, promise a significant increase of the overall benefits obtainable with thrombolysis in acute myocardial infarction.

Blood Platelets↗
PubMed1995

Microvascular dysfunction in collateral-dependent myocardium.

OBJECTIVES: The aim of this study was to evaluate myocardial blood flow regulation in collateral-dependent myocardium of patients with coronary artery disease. BACKGROUND: Despite great clinical relevance, perfusion correlates of collateral circulation in humans have rarely been estimated by quantitative methods at rest and during stress. METHODS: Nineteen patients with angina and isolated occlusion of the left anterior descending (n = 14) or left circumflex (n = 5) coronary artery were evaluated. Using positron emission tomography and nitrogen-13 ammonia, we obtained flow measurements at baseline, during atrial pacing-induced tachycardia and after intravenous administration of dipyridamole (0.56 mg/kg body weight over 4 min). Flow values in collateral-dependent and remote areas were compared with values in 13 normal subjects. RESULTS: Flow at rest was similar in collateralized and remote myocardium (0.61 +/- 0.11 vs. 0.63 +/- 0.17 ml/min per g, mean +/- 1 SD), and both values were lower than normal (1.00 +/- 0.20 ml/min per g, p < 0.01). During pacing, blood flow increased to 0.83 +/- 0.25 and 1.11 +/- 0.39 ml/min per g in collateral-dependent and remote areas, respectively (p < 0.05 vs. baseline); both values were lower than normal (1.86 +/- 0.61 ml/min per g, p < 0.01). Dipyridamole induced a further increase in perfusion in remote areas (1.36 +/- 0.57 ml/min per g, p < 0.01 vs. pacing) but not in collateral-dependent regions (0.93 +/- 0.37 ml/min per g, p = NS vs. pacing); again, both values were lower (p < 0.01) than normal (3.46 +/- 0.78 ml/min per g). Dipyridamole flow in collateral-dependent myocardium was slightly lower in patients with poorly developed than in those with well developed collateral channels (0.75 +/- 0.29 vs. 1.06 +/- 0.38 ml/min per g, respectively, p = 0.06); however, the former showed higher flow inhomogeneity (collateral/control flow ratio 0.58 +/- 0.10 vs. 0.81 +/- 0.22, respectively, p < 0.02). A linear direct correlation was observed between flow reserve of collateral-dependent and remote regions (r = 0.83, p < 0.01). CONCLUSIONS: Despite rest hypoperfusion, collateral-dependent myocardium maintains a vasodilator reserve that is almost fully utilized during increases in oxygen consumption. A global microvascular disorder might hamper adaptation to chronic coronary occlusion.

Adult↗
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

Global alteration in perfusion response to increasing oxygen consumption in patients with single-vessel coronary artery disease.

BACKGROUND: Recent evidence suggests that, in coronary artery disease (CAD), myocardial blood flow (MBF) regulation is abnormal in regions supplied by apparently normal coronary arteries. However, the relation between this alteration and MBF response to increasing metabolic demand has not been fully elucidated. METHODS AND RESULTS: MBF was assessed at baseline, during atrial pacing tachycardia, and after dipyridamole (0.56 mg/kg IV over 4 minutes) in 9 normal subjects and in 24 patients with ischemia on effort, no myocardial infarction, and isolated left anterior descending (n = 19) or left circumflex (n = 5) coronary artery stenosis (> or = 50% diameter narrowing). Perfusion of both poststenotic (S) and normally supplied (N) areas was measured off therapy by positron emission tomography and [13N]ammonia. Normal subjects and CAD patients showed similar rate-pressure products at baseline, during pacing, and after dipyridamole. In CAD patients, MBF was lower in S than in N territories at rest (0.68 +/- 0.14 versus 0.74 +/- 0.18 mL.min-1.g-1, respectively, P < .05), during pacing (0.92 +/- 0.29 versus 1.16 +/- 0.40 mL.min-1.g-1, respectively, P < .01), and after dipyridamole (1.18 +/- 0.34 versus 1.77 +/- 0.71 mL.min-1.g-1, respectively, P < .01). However, normal subjects showed significantly higher values of MBF both at rest (0.92 +/- 0.13 mL.min-1.g-1, P < .05 versus both S and N areas), during pacing tachycardia (1.95 +/- 0.64 mL.min-1.g-1, P < .01 versus both S and N areas), and after dipyridamole (3.59 +/- 0.71 mL.min-1.g-1, P < .01 versus both S and N areas). The percent change in flow was strictly correlated with the corresponding change in rate-pressure product in normal subjects (r = .85, P < .01) but not in either S (r = .04, P = NS) or N regions (r = .08, P = NS) of CAD patients. CONCLUSIONS: Besides epicardial stenosis, further factors may affect flow response to increasing metabolic demand and coronary reserve in patients with CAD.

Adult↗
PubMed1994

[Rationale for coronary recanalization using transluminal atherectomy].

Although balloon angioplasty represented a significant advance in the treatment of coronary artery disease, this procedure is limited by acute occlusion and late restenosis. Among the new devices proposed to overcome the limitations of balloon catheters, Simpson's atherocath has the unique property of removing the atherosclerotic plaques from the coronary wall. Size and stiffness of the terminal portion limit the use of the atherocath to the proximal, non tortuous portion of coronary vessels more than 2.5 mm in size. Studies comparing atherectomy with balloon angioplasty have demonstrated a greater acute luminal gain with atherectomy but have failed to prove a clinical advantage from this better initial results. Atherectomy however is a rapidly evolving technology: better devices and more aggressive dilating strategies could significantly modify the conclusions of the earlier studies. In the meantime atherectomy is providing a unique opportunity to study vascular wall pathology.

Angioplasty, Balloon, Coronary↗
PubMed1992

Discordance between responses of contrast echo intensity to increased flow rate in human coronary circulation and in vitro.

According to the Stewart-Hamilton equation flow is inversely related to the area under the time-concentration curve produced by the transit of a detectable indicator. To verify the applicability of this principle for contrast echocardiography, we bolus injected a saccharide echo contrast agent (0.8 ml) into an in vitro circulatory model at variable flow rates. Two-dimensional echo images were digitized, and curves demonstrating the ratio of videointensity over time were derived. As expected, flow was inversely related to the area under the curves (r = 0.93). To apply this principle to human coronary circulation, we bolus injected sonicated iopamidol (4 ml) into the normal left coronary artery of six patients at baseline and after intravenous administration of dipyridamole (0.84 mg/kg in 10 minutes). Echo images were digitized, and myocardial time-intensity curves were derived. The area under the curve after dipyridamole administration (210 +/- 128 gray level.sec) did not appear significantly different from that at baseline (177 +/- 80 gray level.sec). Thus a mismatch exists between contrast echo data obtained in vitro and in human coronary circulation.

Aged↗