Gated single-photon emission computed tomography. The present-day ''one-stop-shop'' for cardiac imaging.

UNLABELLED: Gated single-photon emission computed tomography (SPECT) is the current state-of-the-art approach to myocardial perfusion imaging. Initially, major emphasis was given to the improvement in diagnostic accuracy of myocardial perfusion imaging for the detection of coronary artery disease, because the evaluation of wall motion and thickening allows the recognition of attenuation artifacts and increases the observer's confidence. Different processing algorithms make possible to perform a reproducible and reliable assessment of left ventricular (LV) function, which has been extensively validated against various reference METHODS: Several articles report the additional value of functional data derived from gated SPECT to increase the accuracy of myocardial perfusion imaging in particular patient groups, such as women, to enhance the detection of multivessel coronary artery disease, and to permit the recognition of severe stenosis. An extensive literature indicates that gated SPECT allows a more accurate and reliable prognostic stratification of patients with known coronary artery disease. More recently, the peculiar contribution of gated SPECT in the assessment of myocardial viability has been demonstrated, with the possibility to evaluate in a single myocardial perfusion study the presence of preserved tracer uptake and the amount of contractile reserve through the acquisition of gated SPECT during inotropic stimulation with dobutamine. The most recent advance in the application of gated SPECT is the use of this technique for the reproducible assessment of LV functional changes, at follow-up or during inotropic stimulation, with perfusion data in the background. Various clinical settings, such as assessment of response to medical or resynchronization therapy in dilated or ischemic cardiomyopathy, prediction of outcome in chronic coronary artery disease with LV remodeling, evaluation of different treatment strategies in acute myocardial infarction, could take advantage from the unique combination of perfusion and functional data made possible by the use of gated SPECT. In conclusion, myocardial perfusion imaging with gated SPECT is a convincing reality in the field of cardiac imaging and has a still largely unexplored potential for a wider use in heart disease.

Classification of ischemic dysfunctional myocardium combining perfusion quantification and contractile reserve evaluation using nitrate-enhanced gated single photon emission computed tomography with dobutamine test.

AIM: In patients with ischemic cardiomyopathy, the differentiation of dysfunctional myocardium in scarred versus hibernating is oversimplified. We evaluated a more complex classification using an imaging technique currently employed for viability detection, having as reference the postrevascularization outcome of dysfunctional segments. METHODS: In 35 patients, we performed gated single-photon emission computed tomography (SPECT) (resting and nitrate-enhanced study, the latter with baseline and dobutamine acquisition) before revascularization. The outcome after revascularization was assessed by repeating resting gated SPECT. Dysfunctional segments without functional recovery in postrevascularization gated SPECT were defined scar (either nontransmural or transmural according to tracer activity); those with recovery were divided in stunned (unchanged uptake) or hibernating (improved postrevascularization activity). This reference classification was compared with the categorization based on prerevascularization gated SPECT. RESULTS: Contractile reserve in dobutamine gated SPECT differentiated scarred from viable segments with 78% accuracy. Tracer activity in nitrate imaging distinguished the degree of transmurality. Nitrate-induced activity increase was significantly higher (p<0.0001) in the hibernating segments (14.9+/-20.4%) than in transmural (4.8+/-13.4%) nontransmural scars (3.3+/-13%), or stunned segments (2.2+/-8%). The presence or absence of nitrate-induced activity increase predicted the postrevascularization perfusion changes in viable myocardium and differentiated hibernating from stunned segments. The prerevascularization classification showed a good agreement with the reference categorization (kappa=0.50). Conclusion. Combining contractile reserve evaluation and perfusion quantification within a single study with baseline-nitrate gated SPECT and dobutamine test it is possible to achieve a comprehensive classification of dysfunctional segments.

The role of telecardiology in supporting the decision-making process of general practitioners during the management of patients with suspected cardiac events.

We studied the role of telecardiology in reducing unnecessary hospital admissions of patients with suspected life-threatening cardiac events (CEs), evaluated by general practitioners (GPs). Over one month, 456 consecutive patients (mean age 65 years, SD 19) complaining of typical (10%) or atypical (42%) chest pain, palpitations (19%), dyspnoea (19%) or syncope (10%) were enrolled. Before teleconsultation, the GPs recorded their own opinion (based on clinical evaluation only) about the presence of a CE. Following transmission of the electrocardiogram (ECG), this opinion was compared with that of the cardiologist. In total there was agreement between the GP and cardiologist about the presence of a CE in 316 of the patients (69%) and disagreement in 140 patients (31%). This represents a specificity and sensitivity of the GPs' diagnosis of 76% and 47%, respectively. For 84 of 134 patients judged as having a CE by the GP, telecardiology avoided hospitalization; on the other hand, telecardiology identified a CE in 56 of 322 patients judged as not having a CE by the GP. Telecardiology is a useful tool with which to reduce unnecessary hospitalizations in patients with suspected life-threatening CEs.

Usefulness of distinct activity thresholds according to baseline regional asynergy for predicting functional recovery in patients with chronic coronary artery disease and left ventricular dysfunction: a study with nitrate-enhanced sestamibi gated SPECT.

BACKGROUND: The role of gated single photon emission computed tomography (SPECT) in improving viability detection with the use of perfusion imaging is uncertain. This study aimed to verify whether the classification of baseline regional dysfunction with gated SPECT helps to predict functional recovery with the use of quantitative perfusion imaging. METHODS AND RESULTS: Resting nitrate-enhanced sestamibi gated SPECT was performed in 31 patients with left ventricular dysfunction, who later underwent coronary revascularization. With the use of a 16-segment model, tracer activity was quantified, and wall motion and thickening were estimated with a 4-point scoring scheme. Reversible dysfunction was assessed with follow-up gated SPECT. According to receiver operating characteristic curve analysis, the best overall cutoff for predicting reversible dysfunction in asynergic segments was 50% of peak activity or greater, with 83% sensitivity, 54% specificity, and 64% accuracy. When the segments were divided according to wall motion in resting gated SPECT, the optimal activity cutoff was greater than 68% for hypokinetic and 50% or greater for adyskinetic segments. With the use of 2 thresholds, the overall sensitivity remained good (76%), whereas specificity increased to 73% (P <.0005) and accuracy to 74% (P <.02). CONCLUSIONS: Regional dysfunction assessment directly on perfusion images permits use of different activity thresholds with an improvement over a single cutoff for all asynergic segments. Therefore combining perfusion and functional data with nitrate-enhanced gated SPECT at rest appears to be a promising approach for viability detection.

Long-term efficacy and safety of propafenone and sotalol for the maintenance of sinus rhythm after conversion of recurrent symptomatic atrial fibrillation.

This study was performed to evaluate, using a randomized double-blind, placebo-controlled protocol, the long-term efficacy and safety of propafenone and sotalol in maintaining sinus rhythm after conversion of recurrent symptomatic atrial fibrillation (AF). The maintenance of sinus rhythm in patients with recurrent AF has several potential benefits, the most important being a reduced risk of thromboembolic events. Three hundred patients with recurrent AF (> or = 4 episodes in the last year) and AF at enrollment lasting < 48 hours were randomized to receive either propafenone (mean daily dose 13 +/- 1.5 mg/kg; 102 patients), sotalol (mean daily dose 3 +/- 0.4 mg/kg; 106 patients), or placebo (92 patients). After 1-year follow-up, Kaplan-Meier estimates of the proportion of patients remaining in sinus rhythm were comparable between propafenone (63%) and sotalol (73%) and superior to placebo (35%; p = 0.001 vs both drugs). Symptomatic recurrences occurred later with propafenone and sotalol than with placebo. Nine patients (9%) in the propafenone group, 11 (10%) in the sotalol group, and 3 (3%) in the placebo group discontinued therapy due to adverse effects. Malignant nonfatal arrhythmias due to proarrhythmic effects were documented with sotalol only, and occurred < 72 hours from the beginning of therapy in 4 patients (4%). During recurrences, the ventricular rate was significantly reduced in patients taking propafenone and sotalol (p = 0.001 for both drugs vs placebo). The likelihood of remaining in sinus rhythm during follow-up was higher in younger patients with smaller left atrial size and without concomitant heart disease. In patients with recurrent symptomatic AF, propafenone and sotalol are not significantly different from each other and are superior to placebo in maintaining sinus rhythm at 1 year. Recurrences occur later and tend to be less symptomatic with propafenone and sotalol compared with placebo.

Technetium-99m sestamibi imaging to predict left ventricular ejection fraction outcome after revascularisation in patients with chronic coronary artery disease and left ventricular dysfunction: comparison between baseline and nitrate-enhanced imaging.

Acceptance of technetium-99m sestamibi as a tracer of myocardial viability is growing, particularly when nitrate-enhanced imaging is used. However, few data are available on the ability of 99mTc-sestamibi to predict the evolution of global left ventricular ejection fraction (EF). The aim of this study was to examine the ability of resting and nitrate 99mTc-sestamibi single-photon emission tomography (SPET) to predict EF changes after revascularisation in patients who have chronic coronary artery disease with left ventricular dysfunction. Using baseline resting and nitrate 99mTc-sestamibi SPET, we studied 61 patients scheduled for revascularisation because of left ventricular dysfunction. EF was estimated using two-dimensional echocardiography before and after the intervention. A post-revascularisation improvement of > or =5 EF units was defined as significant. Using a 13-segment model, 99mTc-sestamibi activity was quantified and the nitrate-induced activity changes calculated. Three different criteria for detecting viability (defined as post-revascularisation reversible dysfunction) in asynergic segments were compared: (1) resting 99mTc-sestamibi activity > or =60%; (2) nitrate 99mTc-sestamibi activity > or =65%; and (3) nitrate-induced increase >+10% or nitrate-induced increase < or =+10% and nitrate activity > or =65%. EF increased significantly in 32 patients. The number of viable asynergic segments was significantly higher in these patients than in the remaining 29 subjects, and the difference was greater (P<0.0002) using definition (3) than using either baseline (P<0.002) or nitrate activity (P<0.0005). There was a significant relationship between EF changes and number of viable asynergic segments: Spearman R=0.38, P<0.005 using baseline; Spearman R=0.39, P<0.002 using nitrate activity; and Spearman R=0.55, P<0.000005 using definition (3). According to receiver operating characteristic (ROC) curve analysis, this last criterion achieved the best results (81% sensitivity, 69% specificity and 75% accuracy), with an area under the ROC curve of 0.838; this area was significantly larger than when using either baseline (0.744, P<0.02) or nitrate activity (0.747, P<0.005). 99mTc-sestamibi SPET appears able to predict the evolution of global left ventricular EF after revascularisation, thereby confirming the value of 99mTc-sestamibi as a tracer of myocardial viability. The combination of baseline resting and nitrate imaging seems to significantly improve the diagnostic accuracy of 99mTc-sestamibi SPET for this particular purpose.

Prediction of functional recovery in patients with chronic coronary artery disease and left ventricular dysfunction combining the evaluation of myocardial perfusion and of contractile reserve using nitrate-enhanced technetium-99m sestamibi gated single-photon emission computed tomography and dobutamine stress.

This study aimed to assess whether contractile reserve evaluation using dobutamine gated single-photon emission computed tomography (SPECT) improves the capability of quantitative perfusion analysis to predict functional recovery of viable hibernating myocardium. Resting and dobutamine nitrate-enhanced technetium-99m sestamibi (sestamibi) gated SPECT studies were performed in patients with coronary artery disease who had left ventricular dysfunction. Tracer activity was quantified, and wall motion and thickening visually scored. Reversible dysfunction was identified with gated SPECT repeated after coronary revascularization. Using the best activity threshold, perfusion quantification achieved 85% sensitivity and 55% specificity. Contractile reserve detection was significantly less sensitive (64%, p <0.0005), but more specific (88%, p <0.00001) than perfusion quantification. However, in the subgroup of hypokinetic segments, the sensitivity of contractile reserve assessment was just slightly lower than perfusion quantification (72% vs 91%, p = NS), whereas specificity was significantly higher (94% vs 23%, p <0.00001). Conversely, in the adyskinetic segments, perfusion quantification was significantly more sensitive than contractile reserve (82% vs 59%, p <0.005), but similarly specific (76% vs 85%, p = NS). Therefore, the identification of reversible dysfunction based on perfusion quantification in adyskinetic segments and on contractile reserve detection in hypokinetic segments was significantly more specific (83% vs 55%, p <0.00001) than standard quantitative perfusion SPECT, without major loss in sensitivity (78% vs 85%, p = NS). In conclusion, contractile reserve evaluation using dobutamine gated SPECT enhances the reliability of nitrate-enhanced sestamibi SPECT when used to predict reversible dysfunction in hypokinetic segments, whereas perfusion quantification remains superior in adyskinetic segments.

Nitrate-enhanced gated technetium 99m sestamibi SPECT for evaluating regional wall motion at baseline and during low-dose dobutamine infusion in patients with chronic coronary artery disease and left ventricular dysfunction: comparison with two-dimensional echocardiography.

BACKGROUND: The value of gated single photon emission computed tomography (SPECT) in the assessment of wall motion (WM) in patients with severe perfusion defects and in the evaluation of low-dose dobutamine (LDD)-induced changes is not yet established. In patients with chronic coronary artery disease who have left ventricular (LV) dysfunction, the results of nitrate-enhanced technetium 99m sestamibi (sestamibi) gated SPECT for the evaluation of resting and LDD WM were compared with those of baseline and LDD echocardiography (LDDE). METHODS AND RESULTS: Thirty-seven patients underwent echocardiography and nitrate-enhanced sestamibi gated SPECT within 1 week at rest and during LDD infusion. WM was scored from 1 (normal) to 4 (dyskinetic) by using a 16-segment model. Segments with sestamibi uptake less than 30% were considered unsuitable for WM analysis (36 of 592 segments). Echocardiography was technically unreliable in 10 of 592 segments. The precise agreement between echocardiography and gated SPECT for baseline regional WM was 68.4% (kappa = 0.54), without significant differences for the involved coronary artery territory. The agreement for +/- 1 WM scoring was 96.5% (kappa = 0.94). Contractile reserve during LDD was detected by means of echocardiography in 36% and by means of sestamibi gated SPECT in 33% of baseline asynergic segments. Agreement for detection of WM improvement in response to LDD was 74% (kappa = 0.41). The overall and +/-1 WM score agreement for LDD WM was 67.5% (kappa = 0.50) and 94.7% (kappa = 0.91), respectively. A significant correlation between echocardiography and gated SPECT was observed for both baseline (p = 0.78) and LDD (p = 0.74) WM score index. CONCLUSIONS: In patients with coronary artery disease who have LV dysfunction, nitrate-enhanced sestamibi gated SPECT allows a reliable WM evaluation, both at rest and during LDD infusion, in almost all segments and provides results in agreement with LDDE.

Comparison of baseline and low-dose dobutamine technetium-99m sestamibi scintigraphy with low-dose dobutamine echocardiography for predicting functional recovery after revascularization.

Injection of sestamibi during low-dose dobutamine (LDD) infusion might improve tracer ability to detect viable myocardium. This study investigated the potential value of LDD technetium-99m sestamibi (sestamibi) single-photon emission computed tomography (SPECT) in predicting functional recovery after revascularization by comparing its results with those of sestamibi SPECT at rest and of LDD echocardiography. Before revascularization, 23 patients with chronic coronary artery disease and regional left ventricular dysfunction underwent sestamibi SPECT at rest and, on a separate day, LDD echocardiography and sestamibi SPECT with tracer injection during LDD infusion. Echocardiography at rest was repeated after revascularization. Semiquantitative sestamibi uptake results (grading from 0 = normal to 4 = absent) and wall motion (grading from 1 = normal to 4 = dyskinesia) were evaluated with a 16-segment model. The ventricular wall was divided into 3 vascular territories. At follow-up, 20 of 32 asynergic vascular territories showed functional recovery, whereas 12 showed no changes. For prediction of functional recovery, LDD SPECT achieved better accuracy than SPECT at rest (87% vs 65%, p <0.05); positive and negative predictive values of LDD SPECT were 90% and 83%, respectively, which was not significantly different from the related LDD echocardiographic values (84% and 69%). Thus, LDD sestamibi SPECT appears to be a promising method for detecting myocardial viability, which provides better accuracy than sestamibi SPECT at rest, and achieves predictive values comparable to those of LDD echocardiography.

Radiation patterns of dual concentric conductor microstrip antennas for superficial hyperthermia.

The finite difference time domain (FDTD) method has been used to calculate electromagnetic radiation patterns from 915-MHz dual concentric conductor (DCC) microwave antennas that are constructed from thin and flexible printed circuit board (PCB) materials. Radiated field distributions are calculated in homogeneous lossy muscle tissue loads located under variable thickness coupling bolus layers. This effort extends the results of previous investigations to consider more realistic applicator configurations with smaller 2-cm-square apertures and different coupling bolus materials and thicknesses, as well as various spacings of multiple-element arrays. Results are given for practical applicator designs with microstrip feedlines etched on the backside of the PCB antenna array instead of previously tested bulky coaxial-cable feedline connections to each radiating aperture. The results demonstrate that for an optimum coupling bolus thickness of 2.5-5 mm, the thin, flexible, and lightweight DCC antennas produce effective heating to the periphery of each aperture to a depth of approximately 1 cm, and may be combined into arrays for uniform heating of large area superficial tissue regions with the 50% power deposition contour conforming closely to the outer perimeter of the array.

[Changes in myocardial Tc-99m-sestamibi uptake in asynergic territories during low-dose echo-dobutamine test]. / Modificazioni della captazione miocardica di Tc-99m-sestamibi in territori asinergici durante test eco-dobutamina a bassa dose.

BACKGROUND: Recent data suggest that contractile reserve in dysfunctional but viable myocardium during low-dose dobutamine infusion might be elicited not only by a direct inotropic stimulation but also by an increase in coronary blood flow. Aim of the study was to evaluate the effects of low-dose dobutamine on myocardial perfusion and function in asynergic but viable myocardium. METHODS: Nineteen patients with coronary artery disease and severe regional dysfunction were studied. Both regional ventricular function and myocardial perfusion were assessed at rest (PRE), during low-dose dobutamine (DOB) and, in twelve patients, after revascularization (POST). Regional ventricular function was evaluated with two-dimensional echocardiography using a score index ranging from 1 to 4. Myocardial perfusion was studied using Tc-99m-sestamibi Single Photon Emission Tomography (SPET); uptake defects were graded from 0 (normal) to 4 (absent uptake). For both evaluations the left ventricle was divided in 16 segments and two vascular territories were considered. RESULTS: Low-dose dobutamine elicited contractile reserve in 12 of 24 asynergic vascular territories (DOB+). Compared with PRE scintigraphy, DOB SPET showed perfusion improvement in 10/12 DOB+ and in 3/12 DOB- asynergic territories (p = 0.006). Mean uptake score decrease significantly in DOB+ (from PRE SPET 21.0 +/- 7.2 to DOB SPET 17.6 +/- 7.1; p = 0.0005) but not in DOB- (from SPET PRE 19.0 +/- 5.3 to SPET DOB 19.5 +/- 6.8, p = NS) abnormal territories. Fourteen asynergic territories underwent revascularization. Among them, 9 showed functional recovery after intervention (viable myocardium) and 5 showed no changes (fibrotic myocardium). A functional improvement under dobutamine was observed in 7 viable and in 1 fibrotic territories. Conversely, perfusion improved under dobutamine in 8 viable and in one fibrotic territory. After revascularization the perfusion defect score decreased significantly in viable territories (from PRE SPET 22.1 +/- 7.9 to POST SPET 13.3 +/- 6.6; p = 0.00001) but not in fibrotic regions (from PRE SPET 17.8 +/- 6.0 to POST SPET 15.6 +/- 4.9). CONCLUSIONS: In asynergic myocardium contractile reserve elicited by low-dose dobutamine is associated in most cases with an improvement in Tc-99m-sestamibi uptake. This suggests a possible link between increased blood flow and functional improvement during dobutamine in viable myocardium.

Direct angioplasty and stenting of the infarct-related artery in acute myocardial infarction.

This study provides the incidence of in-hospital and 1-month recurrent ischemia in 118 patients with acute myocardial infarction when an aggressive direct angioplasty strategy was performed, including stenting of the infarct artery. Coronary stenting in acute myocardial infarction is feasible, and acute and 1-month angiographic results after stenting seem superior to those after standard angioplasty alone.

Early coronary angioplasty as compared with delayed coronary angioplasty in patients with high-risk unstable angina pectoris.

BACKGROUND: Percutaneous transluminal coronary angioplasty (PTCA) results in a higher complication rate in patients with unstable angina pectoris than in patients with stable angina. The current management approach is directed towards achieving stabilization by medical treatment in order to reduce the rate of major complications, but the value of a conservative strategy has not been proved by clinical trials, nor has the duration of therapy been established. On the other hand, the definition of unstable angina encompasses a heterogeneous spectrum of patients with different prognoses. It is more appropriate to stratify patients according to different risk in order to evaluate the results of different therapeutic strategies. The purpose of this study was the evaluation of the results of early and delayed coronary angioplasty in patients with high-risk unstable angina. METHODS: We compared immediate and follow-up results of early and delayed coronary angioplasty in a series of 263 patients with high-risk unstable angina because of prolonged (more than 15 min) angina or early post-infarction angina at rest. Early PTCA (within 4 h of the last ischaemic episode) was performed in 110 patients with unstable angina refractory to maximized medical treatment, whereas 153 patients with stabilized angina underwent delayed PTCA (at more than 72 h and less than 1 week from the last ischaemic episode). RESULTS: No significant differences between the two groups were found in primary lesion success rates (92.7% compared with 94.1%), major in-hospital adverse events such as reocclusion (5.4% compared with 2.6%), emergency coronary artery surgery (1.8% compared with 3.2%), myocardial infarction (3.6% compared with 2.6%) and death (1.8% compared with 0.7%). The rates of major adverse events during 6 months follow-up were similar in the two groups: recurrent ischaemia (13.4% compared with 19.7%), repeat coronary angioplasty (11.5% compared with 14.9%), coronary artery surgery (1.9% compared with 4.7%), myocardial infarction (0), and death (0). CONCLUSIONS: The results of this study suggest that an aggressive coronary angioplasty strategy in patients with high-risk unstable angina may result in a favourable outcome both immediately and at 6 months' follow-up, The achievement of a stabilization period seems neither to improve the clinical success rates nor to reduce major cardiac event rates.

[Primary coronary angioplasty for acute myocardial infarction associated with severe left ventricular dysfunction. Results in 50 patients]. / Angioplastica primaria in soggetti con infarto miocardico acuto associato a grave disfunzione ventricolare sinistra. Risultati su 50 pazienti.

BACKGROUND: Considerable controversy exists about the therapeutic value of primary coronary angioplasty for acute myocardial infarction. The available data suggest that primary angioplasty may improve the outcome in patients with cardiogenic shock, while some clinical studies have found no benefit in routine angioplasty in patients with acute myocardial infarction that were considered at high risk because of severe left ventricular dysfunction associated with myocardial infarction. METHODS AND RESULTS: During a 16-month period, 50 patients with acute myocardial infarction and severe left ventricular dysfunction underwent primary coronary angioplasty. Patients were enrolled if angiographic left ventricular ejection fraction was > or = 40% and symptom duration <6 hours, or >6 hours if there was evidence of ongoing ischemia. Optimal angiographic success (<30% stenosis associated with TIMI grade 3 flow) was achieved in 45 patients (90%), and a suboptimal result (>30% and <50% stenosis associated with TIMI grade 3 flow, or <30% stenosis associated with TIMI grade 2 flow) was achieved in 3 patients (6%), while in 2 patients angioplasty failed to reopen the infarct related vessel or was associated with a refractory no-reflow phenomenon. In 5 patients an optimal angiographic result was achieved after coronary stenting. Emergency repeated coronary angioplasty was required in 1 patient with reocclusion of a stented vessel, and after unsuccessful repeated coronary angioplasty, the patient underwent bypass surgery on a semi-elective basis. In 6 patients with multivessel disease, after successful primary angioplasty of the infarct-related vessel, a more complete revasculariziation was achieved with a second coronary angioplasty or bypass surgery before discharge. The in-hospital mortality rate was 6%. The follow-up of 47 patients surviving initial hospitalization was 171 +/- 163 days. There were 2 deaths (4%), both due to congestive heart failure, and 1 nonfatal reinfarction. Two patients (4%), were readmitted to the hospital for recurrent ischemia and both underwent successful repeated coronary angioplasty for restenosis. CONCLUSIONS: The results of this study suggest that in patients with acute myocardial infarction associated with severe left ventricular dysfunction, primary coronary angioplasty may be considered a first choice treatment because of high reperfusion rate, relative low in-hospital mortality and few recurrent myocardial ischemic events.

FDTD electromagnetic and thermal analysis of interstitial hyperthermic applicators. Finite-difference time-domain.

In this paper, the electromagnetic and thermal behavior of interstitial applicators was analyzed by using the Finite-Difference Time-Domain method. Two configurations were considered: a simple insulated dipole antenna radiating in a layered tissue, and an air cooled applicator radiating in a tissue-equivalent phantom. The proposed approach allows a detailed modeling of the complete structure of the applicator. Furthermore, Specific Absorption Rate and temperature distributions can be determined considering real clinical or experimental conditions. The temperature distribution for the air cooled applicator has been compared with experimental results.

Bailout Palmaz-Schatz coronary stenting in 39 patients with occlusive dissection complicating conventional angioplasty.

The purpose of this study was to evaluate feasibility, safety, and efficacy of bailout Palmaz-Schatz stenting in a series of 39 patients with coronary dissection associated with acute or unequivocal threatened closure complicating conventional angioplasty. No anatomical characteristics other than reference vessel diameter < 3 mm were considered as contraindications for bailout coronary stenting. Stringent criteria were adopted in defining optimal results (< 10% residual stenosis, no angiographic evidence of residual dissection), suboptimal results (> 10% residual stenosis or angiographic evidence of residual dissection), deployment failure (failure to deploy the stent because of poor trackability or persistent occlusion despite stent deployment). A total of 49 stents and 7 half-stents were implanted in 36 patients (range 1-5; mean 1.45 +/- 0.84). Successful stenting without in-hospital death, urgent or semielective coronary surgery, stent thrombosis, or Q-wave myocardial infarction was achieved in 33/39 patients (85%). A suboptimal result was associated with an increased risk of in-hospital recurrence of ischemia and other related major adverse events (2/5 patients with suboptimal results vs. 1/31 patients with complete deployment success; P < 0.05). Multiple stents implantation did not carry a significant risk of major cardiac adverse events. The results of this study suggest that bailout Palmaz-Schatz stenting may be considered a stand-alone treatment of coronary dissection if an optimal acute angiographic result is achieved.

[Late thrombolysis in acute myocardial infarct. Demonstration of myocardial tissue salvage by the assessment of pre- and post-thrombolytic perfusion and left ventricular function]. / Trombolisi tardiva nell'infarto miocardico acuto. Dimostrazione del salvataggio di tessuto miocardico mediante valutazione pre- e post-trombolisi della perfusione e della funzione ventricolare sinistra.

BACKGROUND: Pre and post treatment perfusion scintigraphy with Tc-99m-sestamibi is an accurate method to evaluate the effectiveness of thrombolytic therapy in patients with acute myocardial infarction. In the present study this method was used to verify whether thrombolytic therapy performed late (6 to 24 hours) after symptoms onset was still able to produce significant salvage of jeopardized myocardial tissue. METHODS: Fifteen patients (mean age 60.9 +/- 9 years) admitted to CCU 8-23 hours (mean 13.2 +/- 4 hours) after symptoms onset of their first acute myocardial infarction were studied. Both myocardial perfusion and left ventricular function were assessed before and after thrombolysis. Myocardial perfusion was studied using Tc-99m-sestamibi Single Photon Emission Tomography (SPET) before (pre-lysis SPET), 4.4 +/- 0.9 days (post-lysis SPET A) and 32 +/- 6 days (post-lysis SPET B) after thrombolysis. Uptake defects were graded from 0 to 4 using a 20-segment scheme. Regional ventricular function was evaluated using two-dimensional echocardiography before (pre-lysis ECHO), simultaneously with post-lysis SPET A (post-lysis ECHO A) and 32 +/- 4 days after treatment (post-lysis ECHO B); asynergy was graded from 1 to 4. Global left ventricular function was estimated using gated blood pool imaging and measuring the ejection fraction (EF) 5.3 +/- 1 (GBP 1) and 32 +/- 4 days after treatment (GBP 2). Within 6-9 days of admission all patients underwent coronary angiography. RESULTS: In pre-lysis SPET all patients had uptaken defects (score range 17-52, mean 34.6 +/- 12). According to the comparison between pre-lysis SPET and post-lysis SPET A, patients were divided into two groups: 7 patients with perfusion recovery (Group I) and 8 patients with absent or minimal perfusion recovery (Group II). In Group I the mean uptaken score decreased significantly (from pre-lysis SPET 34.2 +/- 12 to post-lysis SPET A 21.7 +/- 7, p < 0.05); in Group II the uptaken score remained unchanged (from pre-lysis SPET 34.8 +/- 12 to post-lysis SPET A 33.6 +/- 12, ns). In post-lysis SPET B both groups showed a defect reduction compared to post-lysis SPET A; however, the defect score of SPET B in Group I was significantly lower than that in Group II (18.7 +/- 16 vs 30.1 +/- 10, p < 0.05). The asynergic score in pre-lysis ECHO was the same in the two groups (19.5 +/- 4); in post-lysis ECHO A no significant decrease was observed in the two groups. In post-lysis ECHO B a significant decrease was seen in Group I (14.8 +/- 5, p < 0.05 vs pre-lysis ECHO and vs post-lysis ECHO A), but not in Group II (19.8 +/- 5, ns); the asynergic score in post-lysis ECHO B was significantly lower in Group I than in Group II (p < 0.05). In GBP 1 the EF was 38% +/- 6 in Group I and 40% +/- 6 in Group II (ns). In GBP 2 a significant increase was registered in Group I (47% +/- 10, p < 0.05), whereas in Group II the EF remained unchanged (40% +/- 6, ns). Coronary angiography showed a patent infarct related vessel in all Group I patients and in 2 Group II patients (p < 0.05). CONCLUSIONS: These results show that in patients with acute myocardial infarction treated with thrombolysis late after symptoms onset it is still possible to obtain an effective reperfusion and the consequent salvage of jeopardized tissue, as demonstrated by the recovery of both regional and global left ventricular function.

Evaluation of coronary artery disease using technetium-99m-sestamibi first-pass and perfusion imaging with dipyridamole infusion.

UNLABELLED: The aims of this study were: (1) to test whether first-pass radionuclide angiocardiography (FPRNA) adds useful information to perfusion scintigraphy; and (2) to assess the relative accuracy of perfusion and functional imaging in combination with dipyridamole for the evaluation of CAD. METHODS: Thirty patients with angiographically proven CAD (17 with prior infarction) were studied on separate days at rest and with dipyridamole infusion (0.7 mg/kg over 4 min). Tomographic images were evaluated using an uptake score. Dipyridamole FPRNA was considered positive in case of stress-induced wall motion abnormality or ejection fraction decrease. RESULTS: The CAD detection rate of perfusion imaging was 100%, while that of FPRNA was 70% using wall motion criteria, 63% using ejection fraction response and 77% considering any abnormality. For CAD localization, perfusion imaging showed 76% sensitivity, 96% specificity and 82% accuracy. FPRNA results were 50%, 100% and 60%, respectively. Perfusion imaging was significantly superior to FPRNA also excluding from the analysis the infarct-related vessels. FPRNA did not identify multivessel CAD, which was correctly detected by perfusion imaging in most cases. Both techniques were more sensitive in case of > or = 90% stenosis, but the difference was more remarkable for FPRNA (sensitivity 65% versus 14%, p < 0.0005). CONCLUSIONS: Dipyridamole FPRNA did not add noteworthy clinical information to perfusion imaging regarding CAD detection and evaluation of disease extent. The main contribution of a positive FPRNA was its relation with coronary obstruction severity. These results confirm the superiority of perfusion over functional imaging in combination with coronary vasodilators.

A dipole-type intracavitary hyperthermic applicator with a metallic reflector: experiments and theoretical analysis.

A water-cooled electromagnetic (EM) dipole, for intracavitary hyperthermia, embodying a metallic reflector to give directional characteristics to the SAR and then to the heating pattern in the biological tissue, is considered. The influence of the reflector on the SAR deposition has been theoretically modelled with an EM analysis which uses the method of moments (MOM). A thermal model, based on the heat transfer equation, is used to predict temperature distribution, which exhibits a directivity related to the angular extension of the reflector. Experiments have been carried out in a polyacrylamide phantom. The temperature distribution detected with a liquid crystal sheet shows fairly good agreement with theoretical predictions.