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Biomedical subjects

R Giubbini

Publications and source records attributed to R Giubbini.

At least 37 records · Page 2Linked to original sources
PubMed1994

Maldistribution of regional myocardial perfusion at rest in patients with coronary artery disease and no previous myocardial infarction, evidenced by 99mTc-Sestamibi scintigraphy.

Since myocardial 99mTc-Sestamibi uptake is closely related to coronary blood flow and the tracer does not redistribute, resting perfusion defects may be observed even in viable regions supplied by vessels with severe stenosis. The incidence and the clinical significance of 99mTc-Sestamibi uptake defects at rest were investigated in 60 men with suspected coronary artery disease and no previous myocardial infarction, in a multicenter study. Of 60 patients, 12 showed normal coronary arteries and 48 significant coronary artery disease (> 50% luminal narrowing). Based on the presence or absence of tracer uptake defects at resting planar scans, the patients were divided into Group 1 (27 patients) and Group 2 (33 patients), respectively. A greater incidence of coronary artery disease (100% versus 64%, p < 0.01) and of multivessel disease (70% versus 36%, p < 0.05) was observed in patients of Group 1. All patients underwent dipyridamole (up to 0.84 mg/kg in 10 min) 99mTc-Sestamibi scintigraphy, which more frequently induced transient 99mTc-Sestamibi uptake defects in Group 1 than in Group 2 (85% versus 42%, p < 0.001). A high incidence of resting 99mTc-Sestamibi uptake defects was observed in patients without previous myocardial infarction; this identified a subset of patients with a higher prevalence of coronary artery disease and multivessel involvement and with a greater impairment of the coronary reserve, as evidenced by a dipyridamole test.

Coronary Circulation↗
PubMed1993

Recovery of myocardial function. The ultimate target of coronary revascularization.

Recovery of myocardial contraction represents an important target of coronary revascularization and the preoperative recognition of viable akinetic (hibernating) myocardium is a crucial point of the preoperative investigation of patients with chronically depressed left ventricular function. In 14 patients dobutamine infusion during echocardiography was utilized to evoke the contractile reserve retained by viable akinetic segments. Redistribution of thallium(TI)-201 after the rest injection was also used to assess the viability of akinetic areas. The wall motion response to dobutamine infusion predicted immediate postoperative improvement in 85 of 93 segments (sensitivity 91.3%) and identified 25 of the 32 segments which did not exhibit early postoperative improvement (specificity 78.1%). Rest redistribution of TI-201 demonstrated high sensitivity (93.0%) but low specificity (43.7%) for predicting the early recovery of regional wall motion. When late recovery was also considered, the specificity of this method increased to 64.0%. Rest distribution of TI-201 identifies viability which is not necessarily associated with the early recovery of function postoperatively. When the echo-dobutamine test is positive, on the other hand, the recovery of function usually occurs immediately after revascularization and the operative risk is expected to be low even in the presence of severely compromised left ventricular function.

Adult↗
PubMed1993

[Stress and ischemic heart disease].

The role of mental stress in ischemic heart disease is two-fold: as a risk factor of coronary artery disease and as a trigger of acute ischemic attacks in patients with established coronary atherosclerosis. The role of stress as a risk factor is still controversial. Data regarding the relationship between occupational factors and development of coronary atherosclerosis have not been confirmed. A type personality, above all when anger and hostility traits are present, seems to be a predisposing factor for the development of coronary artery disease. These data however, were not confirmed in study groups including patients with a higher prevalence of other, more important, risk factors. Stress can have an important role as a trigger of acute ischemic attacks. This is indirectly shown by the circadian distribution of the main manifestations of ischemic heart disease (sudden death, myocardial infarct, ST segment depression). In fact, their incidence is significantly higher in the morning hours, after awakening, when mental stress is higher. In the laboratory setting, mental stress can induce myocardial ischemia in a variable percentage of patients (0 to 80%). Prevalence of mental stress-induced myocardial ischemia varies depending on the stressor used, the patients group and, above all, the diagnostic tool. Ischemic episodes induced by mental stress, in fact, are generally silent and less severe and extensive than those elicited by exercise stress testing. It is therefore often necessary to use methods, such as myocardial scintigraphy, with higher sensitivity for the detection of myocardial ischemia in comparison with ECG. Patients with mental stress-induced myocardial ischemia tend to present higher scores on measures of aggressivity, anger and hostility. These psychological features are related to a hightened cardiovascular reactivity with a brisk and greater increase in heart rate and blood pressure after exposure to stress. It would be therefore useful to identify patients with such a behaviour by psychological assessment and/or analysis of sympatho-vagal balance by analysis of heart rate variability. The mechanism by which mental stress can induce myocardial ischemia is represented by an increase in myocardial oxygen demand, through the increased heart rate and blood pressure, probably associated with an increase in coronary vascular resistance. This last phenomenon is likely caused by small coronary vessel constriction mediated by alpha-adrenergic activation and by a reduced EDRF release by the damaged endothelium.

Acute Disease↗
PubMed1992

Hibernating myocardium in patients with coronary artery disease: identification and clinical importance.

The term hibernating myocardium describes a particular outcome of myocardial ischemia in which myocytes show a chronically depressed contractile ability but remain viable. Revascularization of hibernating tissue causes a recovery of mechanical function that correlates with long-term survival. Therefore it is important clinically to distinguish hibernating from infarcted myocardium, since asynergies due to hibernation will improve on reperfusion, whilst those due to infarct will not. One suggested technique to identify hibernating myocardium is to stimulate the myocytes acutely, but briefly, by administration of inotropic agents while monitoring contractile function by echocardiography. We report our experience on the use of low dosages of dobutamine. Myocardial viability was validated by measuring the recovery in contraction of the akinetic areas after coronary artery bypass surgery by means of intraoperative epicardial echocardiography. The test has a sensitivity of 93% and a specificity of 78%. It is useful for identification of viable myocardium and also for quantification of intraoperative risk in individual patients. Limitations of this test are related to the presence of downregulation of beta receptors and to the impossibility of differentiating hibernating from stunned myocardium. Another useful technique of identifying hibernating myocardium is the use of radionuclear markers for viability. In our experience the two most important tests are (1) rest-redistribution imaging of thallium 201 (which has a high sensitivity of 93% but a low specificity of 44%) and (2) 99mTc-Sestamibi imaging, which provides information on both perfusion and function with a single injection. This latter technique allows differentiation between stunning and hibernating on the basis of coronary flow which is preserved in stunning and reduced in hibernation.

Cell Survival↗
PubMed1992

Assessment of myocardial perfusion with thallium-201 scintigraphy in exercise-induced left bundle branch block: diagnostic value and clinical significance.

Myocardial perfusion scintigraphy with thallium-201 was performed in 33 subjects (mean age 45 years, range 28-61) with exercise-induced, rate-dependent left bundle branch block (LBBB) in order to assess both the value of Thallium-201 myocardial imaging for the diagnosis of coronary artery disease (CAD) and the pathogenesis (ischaemic or not) of the conduction defect. Of the 33 patients evaluated, 16 had chest pain suggestive of CAD and 17 were asymptomatic. None had a history of prior myocardial infarction or clinical and echocardiographic signs of heart disease. LBBB appeared at a heart rate ranging from 70 to 160 b.min-1. Eighteen patients showed repolarization abnormalities (ST segment depression with deep inverted T waves) compatible with ischaemia, after QRS normalization. Thallium-201 myocardial uptake was normal in 12 subjects; in the remaining 21, reversible Thallium-201 defects were demonstrated in the septum (18 patients), septum and apex (2), and septum and infero-apical wall (1). No patient had irreversible defects and all had normal coronary angiography, with negative ergonovine tests for coronary artery spasm. The patients were followed up for a mean of 43 months (range 16-80). One patient died from sudden death, but no cardiac event occurred in the other patients. In conclusion, exercise Thallium-201 myocardial scintigraphy showed a high prevalence (64%) of reversible perfusion defects in a group of patients with exercise-induced LBBB without any evidence of CAD at angiography or coronary spasm at ergonovine test. Moreover, follow-up showed a relatively low rate of major cardiac events.

Adult↗
PubMed1992

Stunned and hibernating myocardium: possibility of intervention.

There are several potential outcomes of myocardial ischemia. When ischemia is severe and prolonged, irreversible damage occurs and there is no recovery of contractile function. When myocardial ischemia is less severe but still prolonged, myocytes may remain viable but exhibit depressed contractile function. Under these conditions, reperfusion restores complete contractile performance. This type of ischemia, leading to a reversible, chronic left ventricular dysfunction, has been termed hibernating myocardium. The difference between this condition and that described before, i.e., prolonged ischemia, which results in further damage on reperfusion, is, most likely, related to residual coronary flow. In the hibernating myocardium, which is always supplied by a narrow coronary artery, blood flow is not low enough to cause progression toward tissue necrosis, but it is low enough to cause pH changes that, in turn, are responsible for the downregulation of myocardial contractility. The level of underperfusion is sufficient to maintain aerobic metabolism of the quiescient myocardium as demonstrated by the absence of lactate and creatine phosphokinase release. There are no doubts that revascularization is essential for hibernated myocardium, and the clinical goal to achieve is the possibility of accurately distinguishing viable from infarcted tissue. A third possible outcome of myocardial ischemia is a postischemic ventricular dysfunction or myocardial stunning. This term describes a transient mechanical dysfunction that persists on reperfusion after a short period of ischemia, despite the absence of irreversible damage. There are numerous clinical conditions in which stunning might manifest.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Transient prolonged postischemic ventricular dilatation documented by 99mTc MIBI scan.

We describe two cases of prolonged postischemic ventricular dilatation during myocardial scintigraphy with 99mTc MIBI, the new perfusion tracer that has only negligible redistribution. Ventricular dilatation, caused by true chamber dilatation and/or subendocardial ischemia, was still present over two hours after the induced ischemic episode, suggesting a prolonged duration of such a commonly believed fleeting scintigraphic finding.

Cardiomegaly↗
PubMed1991

Effects of mental stress on myocardial perfusion in patients with ischemic heart disease.

The purpose of the present study was to determine whether and to what extent mental stress can reproduce the perfusion defects that are known to be induced by exercise. Twenty-four patients with recent myocardial infarction (New York Heart Association functional class I) and evidence of ischemic response were evaluated by means of SESTAMIBI scintigraphy performed once after exercise and then again within 2 days after mental arithmetic. Baseline, exercise, and mental stress planar scintigrams were divided into 15 segments, and each segment was reviewed and scored on a scale of 0 to 3 by experienced observers using circumferential profile analysis. Conflicting scores were resolved by consensus. Electrocardiographic abnormalities were found in 15 of 24 patients during exercise and in none during mental arithmetic. Chest pain was experienced by five patients during exercise and by none during mental stress. Twenty patients showed reversible perfusion defects during mental stress. Of the 360 pooled scintigram segments, 99 evidenced uptake defects during exercise, and 48 of these showed the same defects during mental stress. Twenty of the remaining 51 of 99 segments were adjacent to segments showing reversible hypoperfusion, suggesting milder hypoperfusion in these segments during mental arithmetic than during exercise. Furthermore, 10 segments showed reversible defects only during mental stress such that seven of these occurred in areas adjacent to those that had shown exercise-induced reversible perfusion defects, two occurred in areas that had shown fixed SESTAMIBI defects during exercise, and one occurred in a segment that had shown completely normal uptake during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Circulation↗
PubMed1991

Electrocardiographic markers of ischemia during mental stress testing in postinfarction patients. Role of body surface mapping.

In patients with coronary artery disease, radionuclide investigations have documented a high incidence of mental stress-induced myocardial ischemia in the absence of significant electrocardiographic changes and/or angina. To investigate the causes of the low electrocardiographic sensitivity, we recorded body surface maps during mental arithmetic in 22 normal volunteers and 37 postinfarction patients with residual exercise ischemia. Myocardial perfusion was studied with thallium-201 or technetium-99 (SESTAMIBI) planar scans. In 14 patients, body surface maps were also recorded during atrial pacing at the heart rate values achieved during mental stress. While taking the body surface maps, the area from J point to 80 msec after this point (ST-80) was analyzed by integral maps, difference maps, and departure maps (the difference between each patient's difference map and the mean difference map for normal subjects). The body surface mapping criteria for ischemia were a new negative area on the integral maps, a negative potential of more than 2 SD from mean normal values on the difference maps, and a negative departure index of more than 2. Scintigraphy showed asymptomatic myocardial hypoperfusion in 33 patients. Eight patients had significant ST segment depression. The ST-80 integral and difference maps identified 17 ischemic patients. Twenty-four patients presented abnormal departure maps. One patient presented ST depression and abnormal body surface maps without reversible tracer defect. In 14 of 14 patients, atrial pacing did not reproduce the body surface map abnormalities. The analyses of the other electrocardiographic variables showed that in patients with mental stress-induced perfusion defects, only changes of T apex-T offset (aT-eT) interval in Frank leads and changes of maximum negative potential value of aT-eT integral maps significantly differed from those of normal subjects. Our results confirm the low electrocardiographic sensitivity for detecting mental stress-induced myocardial hypoperfusion in postinfarction patients. ST analysis in the body surface map increases the information content of the electrocardiographic signal. T wave analysis appears to offer fewer diagnostic advantages.

Cardiac Pacing, Artificial↗
PubMed1989

Diagnosis of acute myocardial infarction by indium-111 antimyosin antibodies and correlation with the traditional techniques for the evaluation of extent and localization.

This clinical study evaluated the accuracy of planar myocardial scintigraphy with antimyosin monoclonal antibodies radiolabeled with indium-111 (AMA-Fab) in the detection and localization of acute myocardial infarction (AMI). Fifty-seven patients admitted for suspected AMI were studied; 17 patients underwent thrombolytic therapy with intravenous streptokinase and 11 had clinical signs of reperfusion; 9 had had a previous myocardial infarction. Fifty of 57 patients were discharged from the coronary care unit with a confirmed diagnosis of AMI. The AMA-Fab study results were positive for AMI in 49 patients (98%) and negative in 1 (2%). Among the 7 patients without AMI, 5 had unstable angina, 1 had Prinzmetal's variant angina and 1 had acute pancreatitis. AMA-Fab results were negative in 6 of 7 patients (85%) and positive in 1 (15%). Therefore, the sensitivity and specificity of AMA-Fab scintigraphy were 0.98 and 0.85, respectively. To assess accuracy in defining the extent and location of AMI, AMA-Fab results were compared with those of the electrocardiogram, echocardiogram, technetium-99m pyrophosphate myocardial scintigraphy and coronary angiography and left ventriculography. AMA-Fab scintigraphy showed a good concordance with the traditional techniques in the topographic definition of the infarcted regions. No uptake of AMA-Fab was seen in the regions of previous old infarcts. Ten healthy volunteers also underwent AMA-Fab scintigraphy. No evidence of myocardial tracer uptake was noted in them. No adverse reactions or side effects were noted after injection of AMA-Fab in any patient. It is concluded that planar myocardial scintigraphy with AMA-Fab is a reliable method for AMI detection and location.

Adult↗
PubMed1989

New tracers for the imaging of the medullary thyroid carcinoma.

I-MIBG and 99Tcm(V)-DMSA have been recently proposed as scintigraphic markers of the medullary thyroid carcinoma (MTC). Thirty two patients were examined with 131I- or 123I-MIBG and 26 of these were re-examined with 99Tcm(V)-DMSA (planar and SPECT). From our experience we can draw the following conclusions: (1) the scintigraphic attempt was useless in patients with normal levels of plasma calcitonin (CT): (2) in patients with high plasma CT levels, the sensitivity of the MIBG was better in familiar (3/3 true positive) than in sporadic disease (7/21 true positive; overall sensitivity = 42%); the 99Tcm(V)-DMSA was positive in 16/19 cases, (overall sensitivity = 84%) even in cases which had been false negative with MIBG (6 patients); (3) no false positive results were found; (4) the scan with 99Tcm(V)-DMSA is then suggested as the first imaging approach during the follow up in patients affected by MTC and still having high levels of plasma CT. The MIBG scan should be limited to the patients in whom the possible use of MIBG therapy has to be investigated.

3-Iodobenzylguanidine↗
PubMed1987

Diagnostic accuracy of rest-exercise first pass ventriculography with a fast single crystal gamma camera in detecting coronary artery disease. Study of a group of male subjects without previous myocardial infarction.

Rest and exercise radionuclide ventriculograms were performed in 61 non infarcted, male, patients who underwent cardiac catheterization for chest pain and in 16 normal control subjects. Studies were performed using the first pass method with a fast single crystal gamma camera, which allowed a count rate of 140 +/- 19 Kcounts/sec to be reached during left ventricular filling; the count integral on left ventricular area was 10.8 +/- 1.6 Kcounts and the maximum count/pixel 155 +/- 16. We analyzed sensitivity, specificity, positive and negative predictive value of global ejection fraction (EF) and of the regional wall motion in identifying ventricular function abnormalities due to obstructive coronary artery disease. The regional wall motion was evaluated with four functional images: regional ejection fraction (REF), amplitude (A) and phase (PH) from Fourier analysis and systolic transit times (TT). Sensitivity was near 90% for EF, REF, A and TT, while PH was less sensitive (80%); all functional images were more specific (nearly 90%) than EF (80%). Both sensitivity and specificity were lower for the exercise EKG (59% and 63%, respectively) in this patient group. Significant differences between single vessel and multiple vessel disease were also observed either for the EF increase/decrease (-1.34 +/- 7.4 and -7.82 +/- 9.96; P less than 0.05) or for the number of segments which developed wall motion abnormalities during exercise (1.22 +/- 0.73 and 2.15 +/- 1.04; P less than 0.02). In conclusion, with our method, a fast single crystal gamma camera is suitable for obtaining optimal first pass radionuclide ventriculograms with a count density sufficient either for global or regional left ventricular function evaluation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

[Incidence and clinical significance of involvement of the right ventricle in acute inferior myocardial infarction].

UNLABELLED: The purpose of our study was to evaluate, with noninvasive procedures, the incidence and the clinical picture of right ventricular involvement in patients with acute transmural inferior myocardial infarction. Our study group was constituted of 107 consecutive patients admitted to our Coronary Care Unit within 10 hours from the onset of symptoms; in every patient a standard 12-leads ECG and the precordial leads V3R and V4R were obtained at admission in CCU and then every 12 hours. 80 patients underwent B-mode echocardiographic evaluation within 36 hours and in 93 patients a myocardial scintigraphy was performed, between the 48th and 72nd hour from the onset of chest pain, 1-2 hours after injection of Tc-99m-pyrophosphate. RESULTS: 45 patients (42.1%) had ECG positive for right ventricular infarction, 49 patients (51.6%) had positive Tc-99m-pyrophosphate scintigraphy and 24 patients (30%) positive echocardiography. By using the positivity of ECG and another method at least, patients were separated into 2 groups: group A (associated inferior and right infarction) was constituted of 45 patients, and group B (isolated inferior infarction) was constituted of 62 patients. In group A we noted a higher incidence of hypotension (systolic blood pressure less than 100 mmHg) and oliguria (less than 30 ml/h)- p less than 0.01-, of 2nd and 3rd A-V blocks-p less than 0.001- and primary ventricular fibrillation -p less than 0.01. The incidence of parossistic atrial fibrillation, severe bradycardia or SA blocks and of mortality was not statistically different between the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

[Study of myocardial perfusion by means of scintigraphy with thallium-210 in left bundle branch block induced by exertion].

Myocardial perfusion scintigraphy with 201-TL was performed in a group of subjects affected by exercise-induced, rate-dependent left bundle branch block (LBBB). The aim of the study was: to define the significance of the exercise-induced conduction abnormality: "primitive" or "ischemic". 14 patients, aging 28-58 years (x = 42), 8 with chest pain (4 typical angina, 4 atypical angina) and 6 without any symptoms were studied. None had history of prior myocardial infarction or clinical and echocardiographic signs of heart disease. LBBB appeared at a heart rate ranging from 70 to 160 beats/min. 6 patients showed repolarization abnormalities (ST changes, deep and negative T wave) suggestive for ischemia, during successive QRS normalization. 201-TL-uptake was normal in 5 subjects; in the remaining 9 ones reversible TL defects were demonstrated in the septum (6), in the septum and apex (2), in the septum and inferior-apical wall (1). No patients had irreversible impaired perfusion. All the patients had normal coronary angiography, with negative ergonovine test for coronary artery spasm. In conclusion, in the majority of our subjects (64%) with exercise-induced LBBB, a reversible TL-uptake defect, usually located in the septum without diagnostic value of obstructive CAD, has been observed. Further studies will establish if the TL-defect is only an "apparent phenomenon" due to contraction abnormality secondary to LBBB, or, on the contrary, an expression of myocardial ischemia with normal coronary vessels as a consequence of the LBBB.

Adult↗