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Biomedical subjects

C Marini

Publications and source records attributed to C Marini.

At least 91 records · Page 5Linked to original sources
PubMed1993

Transcranial Doppler evaluation of cerebral blood flow in patients with paroxysmal atrial fibrillation.

Cerebral blood flow was measured by transcranial Doppler sonography (TCD) in 15 patients during and after an attack of paroxysmal atrial fibrillation. During the attack the mean flow velocity (MFV) was reduced significantly in the middle cerebral artery (p < 0.05) and nonsignificantly in the other arteries. The pulsatility index (PI) was reduced in all the arteries but not significantly. During the fibrillation phase the MFV and PI tended to decrease as the heart rate increased. None of the patients showed clinical signs of cerebral ischemia during the attacks. The absence of such signs despite the reduced cerebral blood flow in atrial fibrillation is probably due to the activation of mechanisms of autoregulation.

Atrial Fibrillation↗
PubMed1993

Increased echodensity of transiently asynergic myocardium in humans: a novel echocardiographic sign of myocardial ischemia.

OBJECTIVES: This study was conducted to establish whether changes in myocardial texture can be observed in humans by transthoracic echocardiography during ischemic episodes of different severity and duration induced by various pathogenetic mechanisms. BACKGROUND: Increased echo-reflectivity of ischemic myocardium has been detected in experimental animals by epicardial echocardiography and by backscatter evaluation. METHODS: Transthoracic two-dimensional echocardiographic monitoring with a commercially available electronic sector scanner (2.25- or 3.5-MHz transducer) was performed during 35 episodes of transient myocardial ischemia induced by ergonovine in patients with vasospastic angina (n = 9), by dipyridamole in patients with angiographically assessed coronary artery disease (n = 11) and by balloon occlusion during coronary angioplasty (n = 15). Quantitative texture analysis of gray levels was performed off-line on digitized images during rest conditions, ischemia and the recovery phase in regions showing normal contraction at rest, obvious dyssynergy during ischemia and normal contraction in the recovery phase. In each condition, a control region with normal contraction throughout the study was also evaluated. RESULTS: Chest pain occurred in 23 of the 35 episodes; electrocardiographic (ECG) changes were present in 26 episodes, and consisted of ST segment elevation in 13, ST segment depression in 10 and pseudonormalization of a basally negative T wave in 3. The duration of ischemic episodes was 67 +/- 53 s by symptomatic criteria and 91 +/- 52 s by ECG criteria. The risk region showed an increased end-diastolic mean gray level amplitude in a.u. (arbitrary units) during ischemia (57 +/- 19) compared with rest (38 +/- 15) and recovery (38 +/- 18, p < 0.01). No significant changes were detected in the control region (rest 36 +/- 16 vs. ischemia 34 +/- 18 vs. recovery 31 +/- 13, p = NS). The percent increase in mean gray level was similar in the various types of stress employed (ergonovine, dipyridamole or angioplasty) and was not significantly correlated with either the duration of ST segment shift (r = 0.05, p = NS) or the severity of dyssynergy evaluated semiquantitatively by means of the wall motion score (r = 0.28, p = NS). In the 15 balloon occlusions performed in six patients during coronary angioplasty, the increased echoreflectivity of the risk zone was already evident during echocardiographic sampling performed after 10 +/- 4 s of occlusion (rest 35 +/- 9 vs. 53 +/- 10 a.u., p < 0.01) when no dyssynergy could be detected by quantitative wall motion analysis (percent area change by fixed center of mass reference system 31 +/- 10% at rest vs. 32 +/- 11% after 10 s of occlusion, p = NS). CONCLUSIONS: Transient short-lasting myocardial ischemia is associated with an abrupt increase in myocardial echodensity detectable by videodensitometric analysis applied to standard transthoracic echocardiographic images and is largely independent of the underlying pathogenetic mechanism (reduced blood supply or flow maldistribution with coronary stenosis). During controlled coronary occlusion, increased echodensity precedes the onset of regional dyssynergy.

Analysis of Variance↗
PubMed1993

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

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

Animals↗
PubMed1993

Focal cerebral ischemia in young adults: a collaborative case-control study. The National Research Council Study Group.

Because there is uncertainty about the role of atherogenic and nonatherogenic risk factors for cerebral ischemia in the young, we carried out a multicenter, hospital-based, case-control study. 333 patients (15-44 years) with focal cerebral ischemia (transient ischemic attack or stroke within 8 weeks of admission) were eligible. 25 patients were excluded, according to the protocol. 308 cases were matched by age and gender to one hospital and one population control. Independent risk was shown by logistic conditional regression for migraine with aura [odds ratio (OR) = 14.8], smoking (OR = 3.7), alcohol (OR = 2.8), serum triglycerides (OR = 1.6), arrhythmias (OR = 9.5), mitral stenosis (OR = 56), coronary heart disease (OR = 4.3) and carotid stenosis or occlusion (OR = 41). Serum HDL-cholesterol had a relative protective effect (OR = 0.8). These data confirm the role of atherosclerosis and cardiac diseases as well as migraine with aura and alcohol consumption in the pathophysiology of cerebral ischemia in the young. More thorough prevention programs may contribute to earlier detection and control of all of these risk factors, but further investigations in patients with as yet unidentified risk factors are warranted because the above-mentioned factors do not account for the total risk of ischemic stroke in the young.

Adolescent↗
PubMed1993

A prospective study of cerebral ischemia in the young. Analysis of pathogenic determinants. The National Research Council Study Group.

BACKGROUND AND PURPOSE: The etiology of stroke in the young is different from that in older patients and remains unknown in almost one third of the cases. To gain further insight into both pathogenic and etiologic determinants, we prospectively studied a large number of consecutive young adults with focal cerebral ischemia. METHODS: Three hundred thirty-three patients aged 15-44 years with transient ischemic attack or ischemic stroke within the 8 weeks before hospital admission were recruited and investigated by using a standardized protocol of clinical evaluation, blood tests, electrocardiography, echocardiography, chest roentgenography, and brain computed tomography. Presumed etiology was diagnosed by prospectively applied criteria. RESULTS: Women predominated (61%) among patients under 35 years of age, mainly due to the frequency of cerebral ischemia related to oral contraceptive use, while men outnumbered women (60%) among patients over that age because of a higher prevalence of atherothrombotic disease. Potential cerebral embolism of cardiac origin was the presumed cause of stroke in 23.7%, but conventional sources of emboli were found only in 7.5% of cases. There was a low prevalence of atrial fibrillation among young patients with cerebral ischemia. Mitral valve prolapse was found in 8.4%, as expected, predominantly (71.4%) among the younger patients. The prevalence of stroke over transient ischemic attack was proportional to the likelihood of cardiac embolism. Acute alcohol intoxication was considered a precipitating factor in only three patients. The percentages of cerebral ischemia attributed to arterial dissection (0.3%), oral contraceptive use in women (8.1%), migraine (1.2%), and other associated medical diseases (1.5%) were lower than reported in recent clinical series. CONCLUSIONS: Two different groups of pathogenic determinants predominate in younger women and in older men, supporting public health measures aimed at strict medical control of the recognized cerebrovascular risk factors.

Adolescent↗
PubMed1993

[Unilateral pulmonary edema caused by heart failure. Report of 2 clinical cases].

The authors present two case reports of cardiogenic unilateral pulmonary edema. The information provided by hemodynamic monitoring have not been essential for diagnosis which was bases on clinical, radiological and echocardiographic findings and confirmed by the clinical response to a specific treatment. The authors briefly review the mechanisms which may cause the atypical distribution of the cardiogenic pulmonary edema.

Aged↗
PubMed1992

Safety of intravenous high-dose dipyridamole echocardiography. The Echo-Persantine International Cooperative Study Group.

Clinical data on 10,451 high-dose (up to 0.84 mg/kg over 10 minutes) dipyridamole-echocardiography tests (DET) performed in 9,122 patients were prospectively collected from 33 echocardiographic laboratories, each contributing greater than 100 tests. All patients were studied for documented or suspected coronary artery disease (1,117 early [less than 18 days] after acute myocardial infarction and 293 had unstable angina). Significant side effects including major adverse reactions and minor but limiting side effects occurred in 113 patients (1.2%). Major adverse reactions occurred in 7 cases (0.07%). In 6 of these cases, adverse reactions were associated with echocardiographically assessed ischemia and included 1 prolonged cardiac asystole (complicated by acute myocardial infarction and coma, with death after 23 days), 1 short-lasting cardiac asystole, 2 myocardial infarctions, 1 pulmonary edema and 1 sustained ventricular tachycardia. In all 6 cases, the cardiologist-echocardiographer performing the study had a limited experience (less than 100 tests) with DET, and at off-line reading in 5 cases, the obvious echo-positivity preceded the onset of complications by 1 to 5 minutes. The only ischemia-independent major side effect was a short-lasting cardiac asystole that was reversed by aminophylline and atropine. Significant side effects associated with echocardiographically assessed ischemia occurred in 89 additional cases (21 with and 68 without concomitant echocardiographically assessed myocardial ischemia). The most frequent of these side effects was hypotension or bradycardia, or both, which occurred in 40 patients with negative and 6 with positive DET. In all cases, side effects promptly subsided after aminophylline. In 1,857 cases, the high dose was not given for echo-positivity before the eighth minute.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Atrial natriuretic factor in essential hypertension: echocardiographic and humoral correlates.

Aim of this study was to assess the relationship between plasma concentration of atrial natriuretic factor (ANF) and its two-dimensional echocardiographic (left ventricular mass, left atrium diameter) and humoral (plasma renin and aldosterone) variables in essential hypertension (EH). We evaluated 32 patients with uncomplicated mild to moderate EH and 10 controls. They were studied in the supine position after 7 days of constant dietary sodium intake and were off therapy since at least 3 weeks. ANF values overlapped between EH patients and controls (27.8 +/- 11.5 vs. 19.5 +/- 7.4 pg/ml, p = NS). In EH, no significant correlation was found between ANF values and left ventricular mass (r = 0.29), left atrial diameter (r = 0.04), mean arterial blood pressure (r = 0.26), plasma renin activity (r = 0.00), and aldosterone (r = 0.26). In EH, ANF values overlapped between the 15 patients with hypertrophy and the 17 patients with normal ventricular mass: 30.3 +/- 17 vs. 25.6 +/- 10.6 pg/ms (p = NS). We conclude that there is a substantial overlap in plasma ANF values between mild to moderate uncomplicated EH and controls, and left ventricular hypertrophy is not a major independent stimulus to ANF release in EH.

Adult↗
PubMed1992

Reproducibility of transcranial Dopplersonography: a validation study.

Transcranial Doppler-sonography (TCD) is a useful noninvasive technique for the measurement of intracranial arterial blood flow velocity. The present study evaluated the reproducibility of this method for repeated measurements of flow velocity in the anterior, middle and posterior cerebral, and basilar arteries. Thirty-six patients (23 males and 13 females) were studied. Three measurements were made by the same examiner on each patient with a time interval of 1 h between the first and the second examination, and about 24 h between the first and the third examination. The statistical evaluation for the reproducibility was performed by calculating the correlation coefficient (r). The results showed good reproducibility of TCD for all arteries both between the first and second and between the first and third measurements (r = 0.78-0.97; p less than 0.001), but when the middle cerebral artery mean velocity is low the posterior cerebral artery reproducibility is poorest (r = 0.42-0.54).

Blood Flow Velocity↗
PubMed1992

Reduction of the extent of ischemic skeletal muscle necrosis by perfusion with oxygenated perfluorocarbon.

Oxygenated perfluorocarbon emulsion has been shown to preserve feline cerebral function after ischemia. The postulated protective effects of perfluorocarbons include improvement of blood rheology and prevention of neutrophil adherence by nonchemical inhibition of surface receptors. In this study, we used a well-described gracilis muscle model to investigate whether oxygenated perfluorocarbon can minimize skeletal muscle necrosis by mitigating the degree of leuko-sequestration. In eight adult mongrel dogs, both gracilis muscles were weighed and then subjected to 6 hours of normothermic ischemia followed by 48 hours of normothermic reperfusion. However, one randomly selected side (experimental side) was infused with oxygen (O2) Fluosol-DA 20% (4.4 +/- 0.2 mL O2/100 mL) intra-arterially at 12 mL/min for 40 minutes immediately after ischemia. Muscle biopsy specimens were obtained before ischemia and after 1 hour and 48 hours of reperfusion to estimate myeloperoxidase (MPO) activity, a marker of neutrophil infiltration. After 48 hours, both gracilis muscles were harvested and weighed in all animals. Muscle necrosis was measured by serial transections, nitroblue tetrazolium staining, and computerized planimetry. The transmuscular oxygen tension (pO2) of the gracilis muscle on the experimental side increased from 2 to 4 mm Hg during ischemia to 315 +/- 50 mm Hg during O2 Fluosol-DA 20% infusion. The percentage of muscle necrosis on the control side was 48.08% +/- 8.46%, compared with 27.62% +/- 6.96% on the experimental side (p less than 0.001). MPO activity was significantly higher at 48 hours of reperfusion compared with pre-ischemic and 1-hour reperfusion values (5.46 +/- 1.52 U/mg tissue protein versus 0.06 +/- 0.01 U/mg tissue protein and 0.16 +/- 0.06 U/mg tissue protein, respectively, in the control group; 1.78 +/- 0.60 U/mg tissue protein versus 0.16 +/- 0.08 U/mg tissue protein and 0.27 +/- 0.10 U/mg tissue protein, respectively, in the experimental group, p less than 0.05). However, MPO activity at 48 hours of reperfusion in the experimental group was significantly lower than in the control group (p less than 0.05). There was no difference in the percentage of weight gain between the control and the experimental groups (38.31% +/- 9.36% and 28.34% +/- 7.35%, respectively, p greater than 0.05). These data show that perfluorocarbons minimize the extent of skeletal muscle necrosis in this canine model. Based on our data on MPO activity, we believe t hat the protective effect of perfluorocarbons is in part due to th e decreased leuko-sequestration in the muscle during the the periods of ischemia and reperfusion.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1992

Cerebral blood flow in migraine with aura: a transcranial Doppler sonography study.

Transcranial Doppler sonography examination was performed on 44 patients with migraine with aura and 88 controls. All patients were investigated in headache-free periods and 10 of them also during a migraine attack. During the headache-free period a not significant increase of mean flow velocity in patients compared to controls was obtained. The pulsatility index (PI) mean values were also higher in patients than in controls and the differences were significant in the MCA (p < 0.05). No difference between right and left side was observed. During the attack the mean flow velocity (MFV) decreased in all arteries but the decrease was significant only in MCA and ACA (p < 0.05). The mean PI increased in all arteries but not significantly. These variations were observed both on the headache and contralateral side. Nevertheless, the MFV decrease in all arteries was observed in four patients only. In four patients the MFV decrease was found in the anterior arteries and the MFV increase in the posterior arteries, while in two patients the MFV increase was observed both in the anterior and posterior arteries. The correlation between the variations of MFV values during the attacks and the time interval from the onset of attacks showed that the PCA and BA flow velocities were increased in patients examined between 0.5 and 3 hours, while an increase in MCA and ACA flow velocities were observed only in patients examined after 1.5 hours.

Adult↗
PubMed1992

Dipyridamole-echocardiography: clinical usefulness following interventions.

Dipyridamole-echocardiography test response can be expressed not only in a black or white (positive vs negative) code but also, in positive tests, by a gray scale integrating the severity and extent of the dyssynergy as well as the ischemia-free stress time. The recognition of the dyssynergy is important to establish the diagnosis; however, the evaluation of the degree of the induced ischemia, stratified according to spatiotemporal coordinates, is even more important because it accurately predicts the coronary anatomical and functional situation, as well as the prognosis of the individual patient. Furthermore, the "shades of gray" in a positive response have proved useful in assessing the beneficial effects of several interventions: coronary angioplasty; coronary artery bypass surgery; thrombolysis; and medical antianginal therapy. Due to its excellent reproducibility, dipyridamole-echocardiography can play a pivotal role for simple, safe, fast, accurate, and objective assessment of therapeutic interventions, either mechanical or pharmacological, based upon the presence, timing, severity, and extent of dipyridamole-induced dyssynergy.

Angina Pectoris↗
PubMed1992

Activation of sympathetic tone during dipyridamole test.

Cardiac imaging with dipyridamole infusion has been proposed as an exercise-independent tool for the diagnosis of coronary artery disease. Dipyridamole acts through the accumulation of adenosine, which reduces sympathetic tone in vasomotor nuclei of the brainstem and inhibits norepinephrine release in noradrenergic neurons but also activates arterial chemoreceptors. The aim of this study was to assess whether dipyridamole administration (up to 0.84 mg/kg over 10 minutes, a dosage commonly employed for diagnostic testing) may modulate sympathetic activity either directly or indirectly through blood pressure reduction or myocardial ischemia, which may be evoked by dipyridamole infusion and represent two recognized sympathetic stimuli. Twenty patients were studied with infusion combined with two-dimensional echocardiography and 12-lead ECG monitoring. Blood pressure was recorded each minute by a cuff sphygmomanometer. In all patients, we obtained venous blood samples for epinephrine (an index of adrenomedullary catecholamine release) and norepinephrine (an index of neuronal activity) both in resting conditions and at peak dipyridamole, ie, at the first minute after termination of dipyridamole infusion in negative cases or in the presence of obvious ischemia in positive cases (ie, as soon as a regional ventricular dyssynergy or an ST segment depression greater than 0.1 mV appeared). Epinephrine and norepinephrine determinations were made by a high performance liquid chromatography (HPLC) method. After dipyridamole, there was a significant rise in norepinephrine, while epinephrine did not change significantly. Dipyridamole-induced percentage variations of norepinephrine from baseline were not significantly correlated with mean blood pressure changes (r = .1, p = ns) and were of a similar extent in patients with (n = 10) and without (n = 10) dipyridamole-induced ischemia (+68 vs +73 percent, p = ns). Dipyridamole administration provokes an activation of sympathetic tone which can be detected even in the absence of myocardial ischemia and is not related to blood pressure changes. The increased catecholamine release appears to be of neuronal rather than adrenomedullary origin.

Adult↗
PubMed1992

The value and limitation of iloprost infusion in decreasing skeletal muscle necrosis.

Iloprost has been shown to minimize skeletal muscle necrosis when administered before the onset of ischemia in animal experiments, possibly by preventing neutrophil activation. Since patients with acute limb ischemia are seen after the process has begun, we investigated whether iloprost can be protective when given only during reperfusion. After anesthesia, 18 adult mongrel dogs underwent a standard isolated gracilis muscle preparation. In six control animals (group I) the gracilis muscle was subjected to 6 hours of ischemia followed by 48 hours of reperfusion. Group II animals (n = 6) received intravenous infusion of iloprost at a dose of 0.45 microgram/kg/hr beginning 1 hour before the onset of muscle ischemia and throughout the experiment (6 hours of ischemia and 1 hour of reperfusion). In addition to the continuous infusion, they received 0.45 microgram/kg intravenous boluses of iloprost 10 minutes before the induction of ischemia and 10 minutes before reperfusion. Group III animals (n = 6) had a similar ischemic interval, but were given a bolus of iloprost of 0.45 microgram/kg at end ischemia followed by continuous infusion of 0.45 microgram/kg/hr for 48 hours during reperfusion. Muscle biopsies were obtained at baseline and after 1 hour of reperfusion in all groups. Additional biopsies were obtained at 48 hours of reperfusion in groups I and III. Myeloperoxidase activity, a marker of neutrophil activation, was measured in all muscle biopsies. At the end of reperfusion, the gracilis muscle was harvested in all animals and weighed. Muscle necrosis was estimated by serial transection, nitroblue tetrazolium histochemical staining followed by computerized planimetry.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1992

[The risk of pulmonary embolism in neurosurgery].

Pulmonary embolism (PE) is a frequent necroscopic finding in neurosurgical patients and this contrasts with the difficult diagnosis of it when the patient is still alive. Such a lack of diagnosis has promoted numerous studies into deep-vein thrombosis (DVT) which is, in most cases, the cause of pulmonary embolism. However, a prophylaxis of DVT cannot be indiscriminately carried out in neurosurgical patients because it is not without potential risks. For this reason we considered it useful to investigate whether among the risk factors for DVT there were any particularly responsible for the development of PE in neurosurgical patients. Our case study was carried out retrospectively on 144 patients hospitalised in the Neurosurgical Institute of Pisa University suspected of PE. In 88 of the cases the suspicion had been confirmed by perfusion lung scanning; in 56, on the other hand, it had been excluded. These two groups of patients resulted homogeneous for sex, age, blood group, and for the presence of any risk factors of cardiovascular diseases. An important difference between the two groups was the pathology which had motivated their hospitalisation; in fact, 50% of the patients with PE were affected by neoplastic pathologies of the CNS, against 28% of the others. The anamenestic evidence of previous neoplastic pathology in different sites of the CNS was much more frequent in patients who had developed PE. As far as the other risk factors we examined are concerned, it resulted that only 12.5% of the patients with PE had presented clinical signs or symptoms of phlebitis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Stress echocardiography and the human factor: the importance of being expert.

The aim of this study was to evaluate how the diagnostic accuracy of a stress echocardiographic procedure, such as a dipyridamole echocardiography test, depends on the specific experience of the physician interpreting the test. Recordings of 50 consecutive dipyridamole echocardiographic tests were selected for the first part of the study. They were analyzed by 20 experienced echocardiographers with different backgrounds in stress echocardiography: 10 beginners (less than 20 stress studies interpreted with trained staff) and 10 experienced observers (greater than or equal to 100 stress studies performed). Diagnostic accuracy (true positive + true negative/total number of tests) versus the angiographic reference standard (greater than 70% coronary stenosis of at least one major coronary artery) was 62 +/- 6% for beginners and 85 +/- 3% for experienced observers (p less than 0.0001). In the second part of the study, 10 observers (5 beginners and 5 experienced observers) evaluated 2 different sets of 50 dipyridamole echocardiographic test studies before and after the training of the beginners. Before training, the accuracy of beginners was lower than that of experienced observers (61 +/- 7% versus 85 +/- 3%; p less than 0.001). After training, the accuracy gap was closed (83 +/- 3% versus 86 +/- 2%; p = NS). Therefore, interpretation of stress echocardiographic tests by an echocardiographer without specific training severely underestimates the diagnostic potential of this technique. One hundred stress echocardiographic studies are more than adequate to build the individual learning curve and reach the plateau of diagnostic accuracy that the test can yield.

Coronary Angiography↗