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G Sambuceti

Publications and source records attributed to G Sambuceti.

65 records · Page 4Linked to original sources
PubMed1988

Frequent occurrence of silent ischaemia in patients with isolated right coronary artery stenosis: a radioisotopic study.

Silent ischaemia has been widely investigated limiting the diagnostic approach to the left ventricle. To date, no systematic study on silent ischaemia in patients with demand-induced right ventricular dysfunction has been reported. The occurrence of painless ischaemic episodes was evaluated by atrial pacing and radionuclide angiography in 20 consecutive patients with single right coronary artery stenosis and without previous myocardial infarction. At the peak pacing rate all patients showed transient myocardial dysfunction (reduction of ejection fraction and/or development of wall-motion abnormalities) localized to the right, the left, or to both ventricles in 9, 1 and 10 patients, respectively. Eight patients experienced chest pain (group 1) and 12 were asymptomatic (group 2) at the maximal pacing rate. Basal left ventricular ejection fraction (55 +/- 4% vs. 55 +/- 5%), basal right ventricular ejection fraction (48 +/- 4% vs. 46 + 8%), peak pacing left (52 +/- 9% vs. 50 +/- 11%) and right (38 +/- 7% vs. 37 +/- 9%) ventricular ejection fractions, and maximal pacing pressure rate product (17,289 +/- 2880 vs. 19,244 +/- 3806) were not significantly different in the two groups. This study demonstrates a high prevalence of silent ischaemia in patients with single right coronary artery stenosis and pacing-induced dominant right ventricular dysfunction. Painful episodes do not appear to be related to the magnitude of changes in ejection fraction.

Coronary Disease↗
PubMed1988

[Right ventricular dysfunction in demand-induced ischemia in patients with isolated right coronary artery disease: a radioisotope study].

In ischemic heart disease, the left ventricle has been considered the main target of an imbalance between myocardial oxygen supply and demand. Accordingly, the approach to ischemia has been directed at the evaluation of the left ventricle. The aim of this study was to assess the relative involvement of the left and right ventricle in patients with isolated right coronary artery stenosis. We studied 20 patients with a clinical history of effort angina (15 male, 5 female, mean age 54.1 +/- 6.2) using radionuclide angiography and atrial pacing. Findings were compared with those of 6 normal subjects that were paced at the maximal heart rate of 150 beats/min. Atrial pacing was interrupted because of diagnostic ST segment depression in 8 patients, Wenckebach type atrioventricular block in 1, chest pain without electrocardiographic changes in 4 and the achievement of the maximal prefixed heart rate of 150 beats/minute in 7. With respect to control conditions, during atrial pacing right ventricular ejection fraction declined from 46.8 +/- 6.8% to 37.4 +/- 8.1% (p less than 0.001), while no significant change was observed in left ventricular ejection fraction values (55.2 +/- 4.5% and 51.1 +/- 10.2% respectively). During atrial pacing, left ventricular peak filling rate increased from 1.77 +/- 0.53 to 4.71 +/- 1.8 end-diastolic volumes/second (p less than 0.0001). Qualitative analysis of regional wall motion showed a right ventricular dysfunction in 19/20 patients; this was prevalent in 9 and involving also the left ventricle in 10; an isolated impairment of the left ventricle was observed in 1 patient.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Regional concordance and discordance between rest thallium 201 and sestamibi imaging for assessing tissue viability: comparison with postrevascularization functional recovery.

BACKGROUND: Whether the combined analysis of rest 201Tl and sestamibi uptake provides additional information regarding myocardial viability in patients with coronary artery disease is still to be investigated. METHODS AND RESULTS: To this aim we studied 22 patients with previous myocardial infarction and regional ventricular dysfunction by quantitative rest sestamibi and 201Tl scintigraphy. All patients underwent revascularization, and echocardiography was repeated 11 +/- 2 weeks later. Concordant results were obtained in 80 of 105 dyssynergic segments. Fifty-one segments showed normal and 29 abnormal activity. Follow-up echocardiography showed increased wall motion contractility in 76% of segments with maintained 201Tl and sestamibi uptake and in only 17% of segments characterized by subthreshold activities. Twenty-five segments, or 24%, showed sestamibi/201Tl mismatch. Eleven of 12 segments with normal sestamibi/abnormal 201Tl activity did not improve after revascularization, whereas 11 of 13 segments with abnormal sestamibi but normal 201Tl showed postoperative improvement of regional wall motion. CONCLUSIONS: In patients with previous myocardial infarction, sestamibi and 201Tl showed concordant results in most segments. However, in segments with mismatch a maintained sestamibi uptake was a poor indicator of tissue viability, whereas significant 201Tl uptake reflected tissue viability in most segments.

Adult↗
PubMedDate not supplied

Correlation between extent of myocardial dysfunction and markers of irreversible damage in failing hearts.

BACKGROUND: The structural correlates of 201Tl uptake in patients with advanced postischemic pump dysfunction are unclear. There are no good experimental models adequately reflecting the mixture of normal, dysfunctional but viable, and necrotic regions characteristic of chronic ischemic heart disease in human beings. METHODS AND RESULTS: Four heart transplant candidates with idiopathic dilated cardiomyopathy and seven with ischemic heart disease underwent rest-injection 4-hour redistribution 201Tl single-photon emission computed tomography before surgery. Delayed tracer uptake was categorized into severely reduced (<50%), mildly or moderately reduced (50% to 74%), and normal (> or =75%) and related to echocardiographic wall motion and histologic findings in the hearts excised at transplantation. In idiopathic dilated cardiomyopathy, despite severe wall motion impairment, minimal or mild myocardial damage and homogeneously high 201Tl uptake were found. In ischemic heart disease, wall motion did not discriminate extensive from mild structural damage. 201Tl activity was inversely related to myocardial fibrosis (r = -0.50, p = 0.0001). Severe defects in 201Tl uptake (<50%) predicted extensive (>30%) fibrosis with 83% sensitivity and 63% specificity. Segmental akinesis and apical location resulted in loss of sensitivity (74% and 58%, respectively). No histologic or wall motion abnormality accounted for poor specificity. In the individual patient, more than nine segments determined viable by imaging criteria predicted left ventricular fibrosis of less than 15% with 86% accuracy. CONCLUSIONS: This histopathologic-clinical correlative study supports current evidence of good sensitivity but limited specificity of 201Tl rest-redistribution tomographic imaging in the evaluation of viable myocardium. In the individual patient, more than nine viable segments reliably predicted a limited extension of fibrosis.

Adult↗
PubMedDate not supplied

Myocardial blood flow and perfusion reserve in infarcted patients with stress-induced normalization of previously negative T waves: a positron emission tomography study.

BACKGROUND: The clinical correlations between stress-induced normalization of previously negative T waves (NTW) and regional myocardial blood flow (MBF) regulation and tissue viability remain debatable. METHODS AND RESULTS: To confirm these correlations, 14 patients with previous anterior myocardial infarction (13 Q waves) and NTW on baseline electrocardiographic precordial leads and 10 healthy subjects were studied by means of positron emission tomography (PET). The MBF values were obtained in the anterior infarcted myocardial regions in either resting condition or during dipyridamole infusion, using N-13 ammonia as a flow tracer. Seven subjects had normalization of NTW (Group 1) and 7 had persistent NTW (Group 2) during dipyridamole infusion. The resting MBF values were similar for both Group 1 and Group 2 (0.43+/-0.13 versus 0.51+/-0.15 mL.min(-1).g(-1), respectively; P = not significant) and were significantly lower than in the anterior myocardial regions of healthy subjects (1.03+/-0.23 mL.min(-1).g(-1), P < .001). After administration of dipyridamole, the MBF was significantly higher in Group 1 than in Group 2 (0.88 +/- 0.37 versus 0.55 +/- 0.17 mL.min(-1).g(-1), respectively; P < .05) and markedly lower than in healthy subjects (3.78+/-0.64 mL.min(-1).g(-1), P < .001). Coronary reserves (dipyridamole/resting MBF) were 2.03+/-0.40 and 1.14+/-0.44 in Group 1 and Group 2, respectively (P < .002). CONCLUSION: Despite similar values of resting perfusion, infarcted dysfunctional areas with or without NTW during stress may present different regional MBF responses; normalization of NTW demonstrates higher coronary flow reserve than persistent NTW, suggesting a better preserved coronary microcirculatory function in the former, indicative of the presence of myocardial viability.

Adult↗
PubMedDate not supplied

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History, Modern 1601-↗
PubMedDate not supplied

99mTc-sestamibi: its clinical role as a viability agent.

The correlation between the presence of viable myocardium and 99mTc-sestamibi uptake is still to be defined. Preliminary studies indicate that: 1) reduced 99mTc-sestamibi uptake at rest is not necessarily evidence of scar tissue, and 2) its uptake is correlated to the severity of coronary stenosis. To define the relationship between rest thallium-201 and 99mTc-sestamibi uptake in dyssynergic segments, we studied 10 patients with ventricular dysfunction. 99mTc-sestamibi uptake was higher than thallium-201 uptake in normal segments but was similarly reduced in segments perfused by stenotic coronary arteries with or without wall motion abnormalities. Post-revascularization studies of regional wall motion showed that 99mTc-sestamibi had a positive and a negative predictive accuracy in identifying viable segments of 88 and 69%, respectively; these values were significantly lower than that provided by Thallium-201. 99mTc-sestamibi appears to be a primary perfusion agent with a high sensitivity to blood flow reduction at rest; it can be cautiously used as a viability agent in segments with wall motion abnormalities at rest.

Adult↗