Search PubMed⌕ Search

Biomedical subjects

R Lorenzoni

Publications and source records attributed to R Lorenzoni.

At least 19 recordsLinked to original sources
PubMed2000

[The evaluation of the appropriateness of instrumental exams in cardiology. The case of echocardiography].

BACKGROUND: The aim of this study was to evaluate the appropriateness and utility rates of echocardiograms performed in 309 patients in an outpatient clinical setting. METHODS: Data were collected by means of a questionnaire filled in by the cardiologists who performed the examinations. Appropriateness was evaluated according to international guidelines and scored as class I: appropriate, class II: doubtful appropriateness, class III: inappropriate; the exam was deemed useful if it was able to influence the clinical decision-making; normalcy rate was also checked. The relationship between both the referring physicians and motivation of the exam and its appropriateness, and the relationship between appropriateness and both the normalcy rate and utility of the exam were assessed. RESULTS: An echocardiogram was requested by the cardiologist in 46% of patients; the more common reasons for the exam were arterial hypertension (26%), cardiac murmur (18%), palpitations (15%), and known coronary artery disease (10%). The echocardiogram was appropriate (class I) in 25% of patients, doubtfully appropriate (class II) in 39% of patients and inappropriate (class III) in 36% of patients. The appropriateness rate between the cardiologists was similar to that of other prescribing clinicians (p = NS). The highest class III rate was found in patients with hypertension, while the highest class I rate was found in patients with a cardiac murmur (p < 0.01). Normalcy rate was lower in class I than in class II and III exams (p < 0.001). The utility rate was higher in class I (76%) than in class II (13%) and III (< 1%) exams (p < 0.01). CONCLUSIONS: International guidelines can be used effectively and safely to identify (not to prescribe) the useless echocardiograms.

Chi-Square Distribution↗
PubMed1999

Effect of alpha1-adrenoceptor blockade on coronary vasodilator reserve in cardiac syndrome X.

We sought to test the response of the coronary microcirculation to alpha-adrenoceptor blockade in patients with syndrome X (angina, ischemia-like stress electrocardiogram, and a normal coronary arteriogram). The response of the microcirculation was assessed by quantification of coronary vasodilator reserve (the ratio of hyperemic to resting myocardial blood flow). We investigated 28 patients with syndrome X [18 women, age 54.4 (7.6) years]. Myocardial blood flow was measured at rest and after dipyridamole by using positron emission tomography with H(2)15O. The measurements were made before and after treatment for 10 days with doxazosin (1 mg o.d. for 3 days, followed by 2 mg o.d. for 7 days) or a matched placebo, similarly administered. Patients were randomized to alpha1-blockade or to placebo in double-blind fashion. No significant differences were demonstrable between syndrome X patients treated with doxazosin and those receiving placebo, with respect to resting myocardial blood flow, myocardial blood flow after dipyridamole, or coronary vasodilator reserve (the ratio of the latter two). In addition, no relations were demonstrable among myocardial blood flow, coronary vasodilator reserve, development of chest pain after dipyridamole, or development of ischemia-like ECG changes. Doxazosin had no effect on the perception of chest pain after dipyridamole. No differences were found between the effects of alpha1-blockade with doxazosin or those of placebo with respect to myocardial blood flow in syndrome X. The values obtained for myocardial blood flow and coronary vasodilator reserve for the patients were within the normal range. The data do not support the case for alpha1-mediated vasoconstriction having an etiologic role in the chest pain of syndrome X.

Adrenergic alpha-Antagonists↗
PubMed1999

A report system for PET assessment of myocardial viability.

Coronary bypass surgery can improve the prognosis of patients with heart failure due to coronary artery disease. However, these patients have a high operative risk and should be operated on only if they have a sizeable amount of viable tissue (i.e. asynergic myocardium) that can recover contractile function following coronary revascularization. In the clinical setting, regional wall motion is usually evaluated by two-dimensional echocardiography, whereas retained metabolic activity assessed by positron emission tomography (PET) and 18F-fluorodeoxyglucose is a well-established means for the evaluation of myocardial viability. Unfortunately, the two-dimensional echocardiography and PET reports are often different, and this renders the matching of information difficult and the estimation of the risk-benefit ratio of the operation unreliable. In this paper, we present a report system for the evaluation of myocardial viability with PET. We divided the left ventricle into 16 segments following the proposal of the American Society of Echocardiography for wall motion analysis by two-dimensional echocardiography. Following this partition, three portions of the left ventricle are identified along the long axis: basal, mid and apical. Each plane of the basal and mid portions is automatically divided into six segments with the super-imposition of a radial divider over the short-axis images. Similarly, each plane of the apical portion is automatically divided, but into four segments. This partition of the left ventricle permits a precise match between the information on wall motion obtained with two-dimensional echocardiography and that on viability obtained with PET.

Coronary Artery Bypass↗
PubMed1999

[An economic assessment of the use of abciximab as a coronary angioplasty preparation in the Italian health-care context].

UNLABELLED: Drugs blocking platelet glycoprotein IIb/IIIa receptors (anti-GP IIb/IIIa) have been used effectively to prevent thrombotic events after percutaneous transluminal coronary angioplasty (PTCA). However, the high cost of these drugs calls for an economic evaluation before they can be used systematically within the context of the Italian health-care system. METHODS: The systematic review of three studies (EPIC, EPILOG, CAPTURE) that evaluated the effectiveness of abciximab (the only anti-GP IIb/IIIa drug commercially available in Italy) demonstrated that this drug can prevent thrombotic events (death, myocardial infarction, repeated PTCA, bypass surgery) at six months after PTCA (RR 0.84; IC 95% 0.77-0.91; number needed to treat for the composite end-point 21). We performed an economic evaluation of the use of abciximab, taking into account the cost the drug (2,561,100 Italian lire [ITL]/patient) and the number of events prevented. We calculated the mean cost-effectiveness ratio (cost of each patient without events at six months after PTCA), the incremental cost-effectiveness ratio (cost of each event prevented at six months after PTCA) and the cost of each year of life saved at six months after PTCA. RESULTS: The mean cost-effectiveness ratio was 16.6 million ITL/patient (versus 15.4 million ITL/patient without the use of the drug); the incremental cost-effectiveness ratio was 34.3 million ITL/event prevented; the cost of each year of life saved was 32.3 million ITL. CONCLUSIONS: With abciximab preventing thrombotic events at six months after PTCA, the cost of each patient without events and the cost of each event prevented at six months are within the range of other pharmaceutical procedures in cardiology (e.g. thrombolysis in acute myocardial infarction with tissue plasminogen activator). Our analysis supports the case for the systematic use of abciximab in patients undergoing PTCA.

Abciximab↗
PubMed1998

Effects of ergotamine on myocardial blood flow in migraineurs without evidence of atherosclerotic coronary artery disease.

The effects of intravenous ergotamine (0.25 mg) on basal and hyperemic (dipyridamole) myocardial blood flow (MBF), measured with positron emission tomography and H2(15)O, were assessed in 15 migraineurs in a double-blind, randomized, placebo controlled, crossover study. Ergotamine produced a 27% reduction in hyperemic MBF (2.62 +/- 0.11 vs 3.72 +/- 1.05 ml x min(-1) x g(-1); p <0.05), a 31% reduction in the coronary vasodilator reserve (1.81 +/- 0.50 vs 2.71 +/- 1.15; p <0.01), and a 55% increase in minimal coronary resistance (42.2 +/- 15 vs 26.7 +/- 8 mm Hg x min x ml(-1) x g(-1); p <0.001), suggesting vasoconstriction of the coronary microcirculation.

Aged↗
PubMed1998

Coronary vasodilator reserve is impaired in patients with hypertrophic cardiomyopathy and left ventricular dysfunction.

BACKGROUND: We tested the hypothesis that a reduced delivery of blood to the myocardium is involved in the development of systolic dysfunction of patients with hypertrophic cardiomyopathy (HCM). METHODS AND RESULTS: Eighty-four patients with HCM (62 men, age 43 +/- 12 years) were studied. Left ventricular dimensions and function (fractional shortening) were evaluated by 2-dimensional echocardiography. Myocardial blood flow (MBF) was measured by N13 -ammonia or O15 -water and positron emission tomography at baseline and after dipyridamole; coronary vasodilator reserve (CVR) was calculated as dipyridamole/baseline MBF. Patients with HCM in advanced New York Heart Association (NYHA) classes had lower dipyridamole MBF (NYHA class I = 1.57 +/- 0.64 vs class II = 1.52 +/- 0.58 vs class III = 0.96 +/- 0.32 mL/min per gram; analysis of variance, P <.05) and CVR (NYHA class I = 1.93 +/- 0.64 vs class II = 1.69 +/- 0.54 vs class III = 1.40 +/- 0.43; analysis of variance, P <.05). A positive linear correlation between fractional shortening and dipyridamole MBF was demonstrated (R = 0.23, P <.05), and patients with abnormal fractional shortening had lower dipyridamole MBF (1.07 +/- 0.43 vs 1.58 +/- 0.62 mL/min per gram, P <.01). CONCLUSIONS: Systolic dysfunction in HCM may be caused by a more severe alteration of the coronary vasodilator capacity.

Adult↗
PubMed1998

Pitfalls in the economic evaluation of thrombolysis in myocardial infarction. The impact of national differences in the cost of thrombolytics and of differences in the efficacy across patient subgroups.

BACKGROUND: The economic evaluation of the results of the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Artery (GUSTO) trial found that recombinant tissue plasminogen activator is more cost-effective than streptokinase for the treatment of acute myocardial infarction. AIM: We evaluated the impact on a cost effectiveness analysis, of the differences in the cost of thrombolytics among countries and of differences in efficacy across patient subgroups. METHODS: We considered the crude costs of streptokinase and recombinant tissue plasminogen activator in Germany, Italy, the United Kingdom, and the United States of America, and the 30-day mortality found in the GUSTO trial. We calculated the incremental costs for each life saved when streptokinase is substituted by recombinant tissue plasminogen activator. We also calculated the incremental costs for each life saved for two protocols implying a selective use of streptokinase and recombinant tissue plasminogen activator (age-selective protocol: recombinant tissue plasminogen activator in patients < or = 75 years, streptokinase in older patients; site-selective protocol: recombinant tissue plasminogen activator in anterior acute myocardial infarction, streptokinase in non-anterior acute myocardial infarction). RESULTS: The incremental costs for each life saved when streptokinase is substituted by recombinant tissue plasminogen activator in all GUSTO patients vary greatly among countries: the incremental costs for each life saved are 31%, 45%, and 97% higher in Germany, Italy, and the United States of America compared to the United Kingdom. The use of a site-selective protocol implies a halved cost-effectiveness ratio compared to the use of recombinant tissue plasminogen activator in all cases of acute myocardial infarction. CONCLUSIONS: (1) The cost-efficacy of recombinant tissue plasminogen activator vs streptokinase in acute myocardial infarction varies greatly among countries due to differences in the cost of drugs. (2) A selective use of thrombolytics for some sites of infarction is more cost-effective than the exclusive use of recombinant tissue plasminogen activator.

Aged↗
PubMed1998

Predictive value of dobutamine echocardiography and positron emission tomography in identifying hibernating myocardium in patients with postischaemic heart failure.

OBJECTIVE: To compare the predictive value of dobutamine echocardiography (DE) and positron emission tomography (PET) in identifying reversible chronic left ventricular (LV) dysfunction (hibernating myocardium) in patients with coronary artery disease (CAD) and overt heart failure. PATIENTS: 30 patients (four women) with CAD and heart failure undergoing coronary artery bypass grafting (CABG). METHODS: Myocardial viability was assessed with DE (5 and 10 micrograms/kg/min) and PET with [18F] 2-fluoro-2-deoxy-D-glucose (FDG) under hyperinsulinaemic euglycaemic clamp. Regional (echo) and global LV function (MUGA) were assessed at baseline and six months after CABG. RESULTS: 192 of the 336 (57%) dysfunctional LV segments improved function following CABG (hibernating) and the LV ejection fraction (EF) increased from 23(7) to 32(9)% (p < 0.0001) (in 17 patients > 5%). DE and PET had similar positive predictive values (68% and 66%) in the identification of hibernating myocardium, but DE had a significantly lower negative predictive value than PET (54% v 96%; p < 0.0001). A significant linear correlation was found between the number of PET viable segments and the changes in EF following CABG (r = 0.65; p = 0.0001). Stepwise logistic regression identified the number of PET viable segments as an independent predictor of improvement in EF > 5%, whereas the number of DE viable segments, the baseline LVEF, and wall motion were not. CONCLUSIONS: DE has a higher false negative rate than PET in identifying recoverable LV dysfunction in patients with severe postischaemic heart failure. The amount of PET viable myocardium correlates with the functional outcome following CABG.

Cardiotonic Agents↗
PubMed1998

[An aggressive exercise test is suitable for myocardial scintigraphy].

Exercise myocardial scintigraphy is frequently used as a second step tool in the assessment of coronary artery disease. Little attention has been paid on the exercise protocol used as a stress during scintigraphy. However, the diagnostic accuracy of the test is better if higher heart rate is achieved. The aim of this study was to evaluate if an aggressive exercise protocol was safe and more effective than a standard protocol in achieving higher heart rate. Eighty-four patients (64 men and 20 women, mean age 56 +/- 10 years, range 34-78 years) underwent a standard exercise test (cycloergometry; SET: 25 W increments every 2 min starting from 25 W load) and an aggressive exercise test (AET: 50 W increments every 2 min starting from 50 W load); during AET a myocardial scintigraphy (Tc-99m sestamibi; SPECT) was performed. Heart rate and blood pressure were monitored during the tests and the rate-pressure product was calculated. No patients had major adverse events during either tests. During AET with respect to the SET, higher maximal heart rate (142 +/- 15 vs 134 +/- 16 b/min; p < 0.01) and rate-pressure product (27,293 +/- 4341 vs 25,773 +/- 6690 b/min x mmHg; p < 0.05) were obtained. During AET higher number of maximal (55/84 vs 34/84; p < 0.05) and positive tests (45/84 vs 29/84; p < 0.05) were detected with respect to the SET. Using myocardial scintigraphy as a reference test, the diagnostic accuracy of the SET and AET was 54 and 73% respectively. In conclusion, an aggressive protocol during exercise stress test can safely be used to obtain a greater number of maximal and positive exercise tests.

Adult↗
PubMed1997

Syncope and ventricular arrhythmias in hypertrophic cardiomyopathy are not related to the derangement of coronary microvascular function.

UNLABELLED: Non-sustained ventricular tachycardia on Holter and syncope have been considered risk factors for sudden death in hypertrophic cardiomyopathy. AIMS: In these patients the coronary vasodilator reserve is impaired despite normal coronaries, so we evaluated the correlation between the severity of coronary vasodilator reserve impairment and the occurrence of syncope and non-sustained ventricular tachycardia. METHODS AND RESULTS: Eighty-four patients with hypertrophic cardiomyopathy (62 males, age 43 +/- 12 years) had a two-dimensional echocardiographic study and a 48-h Holter. Myocardial blood flow was measured by positron emission tomography, at baseline and after dipyridamole, and the coronary vasodilator reserve was computed as dipyridamole myocardial blood flow/baseline myocardial blood flow. In 27 patients, subendocardial and subepicardial myocardial blood flow was measured in the septum and the subendocardial/subepicardial ratio was computed. Twenty of 84 patients had at least one syncopal episode, and 26 had at least one run of non-sustained ventricular tachycardia on Holter. Baseline and dipyridamole myocardial blood flow, coronary vasodilator reserve, and baseline and dipyridamole subendocardial/subepicardial myocardial blood flow ratio were similar in patients with and without syncope and with and without non-sustained ventricular tachycardia on Holter. However, patients with non-sustained ventricular tachycardia had larger left ventricular end-diastolic (47 +/- 6 vs 44 +/- 5 mm, P < 0.05) and end-systolic diameters (30 +/- 6 vs 27 +/- 4 mm, P < 0.05). CONCLUSIONS: (1) Coronary vasodilation is not more severely impaired in patients with hypertrophic cardiomyopathy and syncope or non-sustained ventricular tachycardia. (2) The left ventricle is more dilated in hypertrophic cardiomyopathy with non-sustained ventricular tachycardia.

Adult↗
PubMed1997

[Evaluation of the cost-effectiveness of thrombolytic therapy in acute myocardial infarct using tissue plasminogen activator or streptokinase:the Italian perspective].

UNLABELLED: The GUSTO trial demonstrated that tPA is more effective than streptokinase in the therapy for acute myocardial infarction (AMI). Although tPA is much more expensive than streptokinase some recent analyses have demonstrated that the use of this drug is also cost-effective. However, the cost of the two drugs is different in Italy and USA. Moreover, the difference of the efficacy of the two drugs varies greatly among subgroups of patients with AMI. The aim of this study was to assess the cost-effectiveness of the exclusive use of tPA and streptokinase in the general population and in subgroups of patients divided according to age and site of AMI, using the costs of the drugs in Italy (streptokinase 100,600 and tPA 1,524,300 Italian Liras (ItL)/treatment). METHODS: The results of the GUSTO trial (30 day-mortality) obtained in the general population and subgroups (< or = 75 years and > 75 years; anterior AMI and non-anterior AMI) were applied to patients enrolled in the GISSI-2 trial. The number of lives saved and the incremental costs for each life saved were calculated for the use of tPA in respect to the use of streptokinase. Results are referred to the treatment of 1000 patients. RESULTS: In the general population, in respect to the use of streptokinase, the use of tPA would save 10 lives at an incremental cost of 142.370 millions ItL/life saved. The use of tPA in patients aged < or = 75 years would save 11 patients at the incremental cost of 129.427 millions ItL/life saved, while the use of tPA in patients aged > 75 years would save 13 patients at the incremental cost of 109.515 millions ItL/life saved. In anterior AMI, tPA can save 19 patients at the additional cost of 74.932 millions ItL/life saved, while in non-anterior AMI it can save 6 patients at the additional cost of 237.238 millions ItL/life saved. A subgroup analysis demonstrated that 9 lives can be saved with the use of tPA in anterior AMI and streptokinase in non-anterior AMI at the cost of 49.038 millions ItL/life saved, in respect to the exclusive use of streptokinase. CONCLUSIONS: 1. The cost-effectiveness ratio of tPA in the general population with AMI is comparable to that of other expensive therapies (< 150 millions ItL/life saved). 2. However, a strategy implying a selective use of the two drugs is far more cost-effective (< 50 millions ItL/life saved).

Aged↗
PubMed1996

Activated pyrolytic carbon tip pacing leads: an alternative to steroid-eluting pacing leads?

Pyrolytic carbon technology is known for its excellent mechanical properties and electrical conductivity; it is particularly biocompatible and does not require high production costs. The Sorin S100/4 lead is a ventricular passive fixation lead with a hemispherical electrode surface area of 4 mm2; the stimulating tip is made of a graphite core coated by a thin activated pyrolytic carbon layer. We evaluated the acute and medium-term performance of the unipolar version of this lead in 65 patients. At implantation, pacing threshold (at 0.5 ms) was 0.26 +/- 0.08 V; pacing impedance (at 5 V and 0.5 ms) was 537 +/- 94 omega and R wave amplitude was 15.0 +/- 5.5 mV. No lead related complications (dislodgment, perforation, exit block, etc.) occurred in any patient; one patient presented with a wire fracture after 26 months, due to subclavian crush syndrome. Follow-up procedures were performed at 1 week, and 2-, 10-, 18-, and 30-months postimplant. Since the leads were connected to pacemakers from different manufacturers, either voltage or duration thresholds were measured. In approximately two thirds of the patients, with an output of 2.5 V, a mean duration threshold of 0.16 +/- 0.13 ms at 1 week, 0.12 +/- 0.08 ms at 2 months, 0.11 +/- 0.06 ms at 10 months, 0.09 +/- 0.06 ms at 18 months, and 0.07 +/- 0.03 ms at 30 months, was measured. In the remaining one-third of the patients, a comparable voltage threshold trend was measured. The mean pacing impedance showed a transient drop at 1 week, and then increased to a plateau of about 600 omega reached after 10 months. No sensing defect occurred in any patient. Our data show good acute and intermediate-term results of the S100/4 lead; the early rise in threshold was remarkably blunted. Activated pyrolytic carbon tip leads might therefore be considered as a possible, inexpensive alternative to steroid-eluting leads.

Aged↗
PubMed1996

Effect of alpha 1-adrenoceptor blockade on resting and hyperemic myocardial blood flow in normal humans.

In the present study we aimed to assess the effect of alpha 1-adrenoceptor blockade on resting and hyperemic myocardial blood flow in normal humans. Myocardial blood flow, at baseline and after dipyridamole, was measured with positron emission tomography and 15O-labeled water in 11 normal volunteers at control and during alpha 1-blockade with doxazosin. Baseline myocardial blood flow during alpha 1-blockade was not different from control, whereas coronary resistance was significantly lower (73.48 +/- 18.31 vs. 89.84 +/- 27.96 mmHg.min.ml-1.g-1; P < 0.05). After dipyridamole, myocardial blood flow during alpha 1-blockade was significantly higher (3.50 +/- 0.75 vs. 2.58 +/- 0.54 ml.min-1.g-1; P < 0.01) and coronary resistance lower (25.30 +/- 7.37 vs. 33.89 +/- 7.04 mmHg.min.ml-1.g-1; P < 0.01) compared with control. In conclusion, in normal humans, dipyridamole-induced increase in myocardial blood flow is limited by alpha 1-mediated coronary vasoconstriction.

Adrenergic alpha-Antagonists↗
PubMed1995

[Total atrioventricular block as the primary clinical manifestation of undiagnosed aortic dissection].

We describe the case of a 54-year-old male who was examined due to light chest pain experienced the previous day. The man was admitted to the cardiology division for the presence of a complete atrioventricular block. On admission the echocardiogram showed a large aortic regurgitation not present two years earlier. Suspecting an aortic dissection we performed a transesophageal echocardiography and a contrast computerized tomography: the two examinations were negative. The next days the patient had two episodes of acute pulmonary edema so he was transferred to the regional reference hospital where an hemodynamic unit and cardiac surgery division were available. There, he repeated a transesophageal echocardiography which was negative. The man had aortic valve replacement without angiography for his very critical condition. The surgeon identified a small aortic dissection, just above the aortic valve plane, which was responsible for valve leaflets prolapse and aortic regurgitation; the hematoma deepened towards the interatrial septum and atrioventricular junction justifying the atrioventricular block. In conclusion, a small aortic dissection can offer an atypical picture, and in this condition even very valuable diagnostic techniques may fail the diagnosis.

Aortic Dissection↗