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Biomedical subjects

A Conversano

Publications and source records attributed to A Conversano.

8 recordsLinked to original sources
PubMed1999

Catheter ablation of paroxysmal atrial fibrillation using a 3D mapping system.

BACKGROUND: We treated paroxysmal recurrent atrial fibrillation (AF) with radiofrequency (RF) catheter ablation by creating long linear lesions in the atria. To achieve line continuity, a 3D electroanatomic nonfluoroscopic mapping system was used. METHODS AND RESULTS: In 27 patients with recurrent AF, a catheter incorporating a passive magnetic field sensor was navigated in both atria to construct a 3D activation map. RF energy was delivered to create continuous linear lesions: 3 lines (intercaval, isthmic, and anteroseptal) in the right atrium and a long line encircling the pulmonary veins in the left atrium. After RF application, the atria were remapped to validate completeness of the block lines, demonstrated by late activation of the areas circumscribed by the lines. The mean procedure duration was 312+/-103 minutes (range, 187 to 495), with mean fluoroscopy time of 107+/-44 minutes (range, 32 to 185 minutes). No acute complications occurred, but 1 patient experienced early prolonged sinus pauses and received a pacemaker. During the first day, 17 patients (63%) had AF episodes, but at discharge, 25 patients were in sinus rhythm. After a follow-up of 6. 0 to 15.3 months (average, 10.5+/-3.0 months), 16 patients are asymptomatic, 3 have an almost complete disappearance of symptoms, 1 patient is improved, and 7 patients have their AF attacks unchanged. CONCLUSIONS: Paroxysmal recurrent drug-refractory AF can be treated by RF catheter ablation. Creation of long continuous linear lesions necessary to compartmentalize the atria is facilitated by a nonfluoroscopic electroanatomic mapping system.

Adult↗
PubMed1997

Myocardial viability assessed with fluorodeoxyglucose and PET in patients with Q wave myocardial infarction receiving thrombolysis: relationship to coronary anatomy and ventricular function.

In previously thrombolysed patients, we analysed residual myocardial viability using the PET-FDG technique and correlated its presence and extent to the angiographic appearance of the infarct-related vessel and left ventricular function. Thirty-six patients who had undergone intravenous thromboloysis for acute myocardial infarction 4.8 +/- 7.2 months previously were studied. Coronary angiography, left ventriculography, and assessment of myocardial perfusion and metabolism were all performed within 1 week. All patients exhibited perfusion defects consistent with the clinically identified myocardial infarction site. Residual viability, as assessed by the PET-FDG technique, was present in 53% of cases. The infarct-related coronary artery was patent in 19 (53%) patients (TIMI grade 3, 79%); of the remaining 17 with occluded infarct-related arteries, 11 had collaterals to the infarct area. Significant FDG uptake was observed in 63% of patients with a patent infarct-related artery and in 41% of those with an occluded infarct-related artery. The same study protocol was adopted in a control group of 30 patients with myocardial infarction who did not receive thrombolysis. The number of infarct-related patent vessels was significantly lower in these patients (30 vs 53%) (TIMI grade 3, 56%), but the overall percentage of PET viability was again 53%. Qualitative analysis of the regional perfusion pattern showed that the magnitude and severity of the perfusion defect was similar in the two groups, regardless of the presence or absence of FDG uptake. Global left ventricular function was also similar in the two groups. However, regional wall motion was significantly better in the thrombolysed patients with a patent infarct-related artery than in those who had not received thrombolysis and whose culprit vessel was also patent. In conclusion, the results of our study support the notion that early recanalization of the infarct-related artery is critical for preserving left ventricular function. Although the number of patent infarct-related coronary arteries is greater and left ventricular function is better in successfully thrombolysed patients, the regional metabolic pattern does not apparently correlate with the patency of the infarct-related artery. This suggests that, in "chronic' myocardial infarction, residual tissue viability as assessed by fluorodeoxyglucose uptake does not necessarily correlate with coronary recanalization.

Blood Glucose↗
PubMed1996

Delineation of myocardial stunning and hibernation by positron emission tomography in advanced coronary artery disease.

With positron emission tomography, the resting flow abnormalities underlying reversible left ventricular dysfunction in 17 patients with chronic coronary artery disease were delineated. The level of flow in reversible dysfuncTional segments (i.e., those demonstrating improvement after revascularization) was markedly variable, ranging from 0.32 to 1.25 ml/gm/min. In 20 of these segments, flow was preserved, whereas in 12 segments, flow was reduced, when compared with that in, age-matched controls. Preservation of flow was associated with preservation of myocardial oxygen consumption and no alterations in myocardial substrate use. In contrast, a reduction in flow resulted in a decrease myocardial oxygen consumption and an increase in myocardial glucose use. Thus resting reversible left ventricular dysfunction in patients with chronic coronary artery disease can reflect a diversity of resting flow abnormalities. Moreover, myocardial perfusion at rest is frequently within normal limits, suggesting that the reversible mechanical dysfunction in these patients is attributable to intermittent myocardial stunning and not hibernation.

Adult↗
PubMed1993

Time dependence of residual tissue viability after myocardial infarction assessed by [18F]fluorodeoxyglucose and positron emission tomography.

Areas of myocardial infarction may retain glycolytic activity and this finding is indicative of tissue viability and predictive of functional recovery after revascularization. In order to assess the relation between the time elapsed from the occurrence of acute myocardial infarction and persistence of myocardial metabolic activity in the infarcted tissue, we prospectively studied 65 patients with previous myocardial infarction diagnosed clinically and by electrocardiographic (Q wave) and enzymatic criteria. All patients underwent coronary angiography and contrast left ventriculography, evaluation of regional myocardial glucose metabolism (in the fasting state) by positron emission tomography (PET) with 2-[18F]fluoro-2-deoxy-D-glucose ([18F]FDG), and assessment of myocardial perfusion by single photon emission computed tomography (SPECT) with technetium-99m methoxyisobutyl isonitrile (99mTc-MIBI). Based on the regional metabolic and perfusion findings, patients were divided into 2 groups, depending on the absence (group 1, 26 patients) or presence (group 2, 39 patients) of [18F]FDG uptake in the underperfused regions. Areas of underperfusion at rest, consistent with the clinically identified myocardial infarction site, were observed in all patients. Severity of coronary artery disease, presence of collaterals, number of hypocontractile segments, and wall motion score did not differ significantly in the 2 groups. The time elapsed from the infarction was significantly greater (1,860 +/- 1,333 days) in group 1 than in group 2 (92 +/- 115 days; p < 0.0001). Exercise caused an increase in severity and/or extent of resting perfusion abnormalities in a greater proportion of patients of group 1 (53% vs 23%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Comparison of carbon-11-acetate with fluorine-18-fluorodeoxyglucose for delineating viable myocardium by positron emission tomography.

OBJECTIVES: This study was designed to determine in patients with advanced coronary disease whether prediction of recovery of mechanical function after coronary revascularization could be accomplished more effectively by positron emission tomography (PET) with carbon-11 (11C)-acetate than by PET with fluorine-18 (18F)-fluorodeoxyglucose. BACKGROUND: Results of previous studies have demonstrated that preservation of myocardial oxidative metabolism (measured by PET with 11C-acetate) is necessary for recovery of systolic function after coronary revascularization. METHODS: Myocardial oxidative metabolism was quantified before revascularization in 34 patients by the analysis of the rate of myocardial clearance of 11C-acetate. Metabolism of glucose was assessed by analysis of uptake of 18F-fluorodeoxyglucose. Receiver operating characteristic curves for predicting functional recovery were derived for the measurements of oxidative metabolism and glucose metabolism. In addition, criteria for prediction of recovery of function based on measurements of oxidative metabolism and glucose metabolism were developed and compared. RESULTS: Analysis of receiver operating characteristic curves indicated that estimates of oxidative metabolism were more robust in predicting functional recovery than were estimates of glucose metabolism (p < 0.02). Moreover, threshold criteria with 11C-acetate exhibited superior positive and negative predictive values (67% and 89%, respectively) than did the criteria with 18F-fluorodeoxyglucose (52% and 81%, respectively), p < 0.01. In segments with initially severe dysfunction, estimates of oxidative metabolism tended to be more robust than estimates of glucose metabolism in predicting functional recovery. Moreover, in such segments, the threshold criteria with 11C-acetate tended to exhibit superior positive and negative predictive values (85% and 87%, respectively) than did the criteria with 18F-fluorodeoxyglucose (72% and 82%, respectively), although statistical significance was not achieved. CONCLUSIONS: In patients with advanced coronary artery disease, the extent to which functional recovery can be anticipated after coronary revascularization can be delineated accurately by quantification of regional oxidative metabolism by PET with 11C-acetate.

Acetates↗
PubMed1992

Pretreatment with buflomedil enhances ventricular function by reducing the dysfunctional area after transient coronary artery occlusion.

OBJECTIVE: The aim was to evaluate whether buflomedil (a drug used to treat peripheral vascular disease and which has a number of pharmacological actions potentially beneficial to dysfunctional myocardium) would preserve myocardial function after transient coronary artery occlusion followed by reperfusion. METHODS: The physiological response to a 15 min balloon occlusion of the left anterior descending coronary artery followed by 1 h of reperfusion was monitored in 17 placebo treated dogs and compared with that of 15 dogs which received 10 mg.kg-1 of buflomedil. Buflomedil or its vehicle were given intravenously. Myocardial blood flow was assessed with radiolabelled microspheres and cardiac function was evaluated with quantitative contrast left ventriculography. RESULTS: Buflomedil did not affect baseline haemodynamic variables or contractile function. At the end of occlusion, there was no difference between dogs receiving vehicle compared with those receiving drug with respect to ejection fraction [33(SD 11)% v 34(11)%] or transmural blood flow [0.23(0.11) v 0.28(0.14) ml.g-1 x min-1]. However, at 30 min after reperfusion, ejection fraction was 89% of normal in the buflomedil group compared with 69% of normal in the placebo group (p < 0.03). This difference was sustained 60 min after reperfusion, and was due in part to slightly enhanced flow during reperfusion and a decrease in the dysfunctional area (16 compared with 28 chords lower than -2 SD from the mean, p < 0.04) in the hearts of dogs receiving buflomedil. Areas at risk were equivalent (15.9% and 15.8% of the left ventricle, respectively). CONCLUSIONS: The results suggest that buflomedil and agents with similar modes of action may be beneficial in preserving ventricular function after transient ischaemia followed by reperfusion.

Animals↗