Cardiac 123I-mIBG scintigraphy for prediction of catheter ablation outcome in patients with atrial fibrillation.

BACKGROUND: Previous studies show inconsistent results on the role of innervation imaging (with 123I-mIBG) in predicting late atrial fibrillation (AF) recurrence after catheter ablation (CA). These studies included patients with paroxysmal AF and studied prognostic value of post-CA I-123-mIBG parameters. Current study investigated the ability of pre CA 123-I-mIBG imaging to predict late AF recurrence in patients with persistent AF. METHODS: 123I-mIBG cardiac imaging was performed before CA in 82 patients with persistent AF. Patient was followed for 12 months. RESULTS: Multivariable analysis demonstrated that late heart-to-mediastinum ratio (H/Mlate) and washout rate (WR) were independent predictors of AF recurrence. ROC-curve analysis data showed that H/Mlate <1.6 (sensitivity 73.53%, specificity 81.3%, AUC 0.792, P < .001) and WR > 25.11 (sensitivity 70.6%, specificity 70.8.3%, AUC 0.712, P < .001) indicate high probability of AF relapses during 12 months after CA. CONCLUSION: Pre-CA parameters of global cardiac sympathetic activity estimated by 123I-mIBG scintigraphy are associated with late AF relapses in persistent AF patients with normal LVEF and absence of significant CAD.

[Visualisation and Radiofrequency Ablation of Sympathetic Innervation Loci in the Left Atrium in Patients with Paroxysmal Atrial Fibrillation].

INTRODUCTION: A novel cardiac gamma camera utilizes the radiopharmaceutical Iodine-123-Meta-iodobenzylguanidine (123I-MIBG) to visualize cardiac sympathetic innervation. Physiological accumulation of 123I-mIBG provides an anatomical quantitative determination of the structures of the autonomic nervous system (ANS) with discrete uptake areas (DUA) of sympathetic activity located in the left atrium (LA) corresponding to the main ganglionic plexi (GP) clusters that could not previously be visualized. AIM: to visualize the DUA of the heart in patients with paroxysmal atrial fibrillation (AF) and to assess the effect of radiofrequency ablation (RFA) on DUA in LA. MATERIALS AND METHODS: Computed tomography (CT) of the heart and radionuclide imaging with 123I-mIBG were performed in 15 patients with paroxysmal AF. The results of the study were combined with preliminary taken CT images to create a detailed anatomical map of the sympathetic activity of the heart. The processed images were combined with the 3D reconstruction of the LA, obtained with the navigation system (CARTO 3, CARTO RMT). In DUA, high-frequency stimulation (HFS) followed by RF ablation was performed using the current recommended parameters. RESULTS: Forty-eight DUA (median 3 [3; 3]) were identified. Average activity of DUA was 1315 [1171; 1462] cnt / sec / ml. Positive response to HFS in the DUA was obtained in 8 (53.3 %) patients. Prior to ablation, no response was received to HFS in areas of LA outside the DUA. After ablation, there was no response to HFS in the DUA sites. At repeated scans 3 DUA (median 0 [0; 0]; p<0.001 compared with preoperative data) were observed. Activity of DUA significantly decreased to 819 [684; 955] cnt / sec / ml (p<0.001 as compared with preoperative data). Thirteen of 13 of 15 patients (87 %) had no AF / AT / AFL recurrences for 6 month follow up. CONCLUSION: In patients with AF, the areas of sympathetic activity in LA can be visualized by physiological localized uptake of 123I-mIBG. Radiofrequency catheter ablation can target the identified sympathetic innervation structures in AF patients precisely and effectively.

Experimental Study of a Radiopharmaceutical Agent Based on Modified Fatty Acid Labeled with Technetium-99m.

Using rat model of coronary occlusion, we studied pharmacokinetics and the efficiency of a new radiopharmaceutical agent 99mTc-PDA-DTPA intended for diagnostics of changes in myocardial metabolism and its analogue 123I-PMPDA. 99mTc-PDA-DTPA was eliminated mostly by the kidneys and maximal concentration in the heart was attained within 60 min after intravenous injection; no accumulation in the area of myocardial infarction was observed. The studied substance was inferior to its analogue 123I-PMPDA by the quality of scintigraphic visualization of the heart.

[Interrelation of Electrophysiological and Perfusion Changes in Patients With Left Ventricular Aneurysm].

The study was aimed at identification of relations between perfusion and electrophysiological changes in left ventricular (LV) myocardium in patients with ischemic heart disease (IHD) with postinfarction LV aneurysm and ventricular tachycardia. The study enrolled 23 patients with the aforementioned disease. Preoperatively, apart from standard clinical examination of cardiosurgical patients, intracardiac electrophysiological study and perfusion single-photon emission computed tomography of myocardium with 99mTc-Technetril were performed. The patients were subjected to coronary artery bypass grafting and left ventricular reconstruction. Assessment of the outcomes showed that electrophysiological condition of left ventricle was dependent on myocardial perfusion. Electrophysologically normal myocardium with electric potential >1.5 mV, transient zone (0.5-1.5 mV) and zones with the potential <0.5 mV differed significantly by the percentage of perfusion: 61, 45, and 35%, respectively. Zones of delayed conduction and those of double potential were located mostly in transient zone of electrical potential conduction with the current amplitude of 0.5-1.5 mV and myocardial perfusion from 35 to 61%. Double potential zone was formed in the area of myocardium with better perfusion (perfusion defect of 55% with preserved metabolism) as opposed to the zone of delayed conduction, where perfusion defect was 40% with low level of metabolic activity. The obtained data has proven the presence of correlation between electrophysiology and perfusion of myocardium. This provides an opportunity to identify electrically unstable myocardial zones with the help of specific computer tomography of myocardium.

Radiomic Phenotype of Periatrial Adipose Tissue in the Prognosis of Late Postablation Recurrence of Idiopathic Atrial Fibrillation.

The aim of the study is to find new predictors of postablation atrial fibrillation (AF) recurrence in patients with lone AF using a texture analysis of the periatrial adipose tissue (PAAT) of the left atrium. Materials and Methods: Forty-three patients admitted for lone AF catheter ablation, who had undergone multispiral coronary angiography, were enrolled in the study. PAAT segmentation was performed using 3D Slicer application followed by extraction of 93 radiomic features. At the end of the follow-up period, patients were divided into 2 groups depending on the presence or absence of AF recurrence. Results: 12 months of follow-up after catheter ablation, postablation AF recurrence was reported in 19 out of 43 patients. Of 93 extracted radiomic features of PAAT, statistically significant differences were observed for 3 features of the Gray Level Size Zone matrix. At the same time, only one radiomic feature of PAAT, Size Zone Non Uniformity Normalized, was an independent predictor of postablative recurrence of AF after catheter ablation and 12 months of follow-up (McFadden's R2=0.451, OR - 0.506, 95% CI: 0.331‒0.776, p<0.001). Conclusion: The radiomic analysis of periatrial adipose tissue may be considered as a promising non-invasive method for predicting adverse outcomes of the catheter treatment, which opens the possibilities for planning and correction of patient management tactics after intervention.

[Comparative characteristics of revealing hibernated myocardium by means of perfusion and metabolic scintigraphy].

OBJECTIVE: comparative assessment of the informative value of the methods of perfusion and metabolic single-photon emission computed tomography (SPECT) in detecting the hibernated myocardium. MATERIALS AND METHODS: the study included a total of twenty six patients diagnosed with coronary artery disease (CAD). Of these, there were 24 men and 2 women, mean age 52.0±7.0 years. All the patients in order to detect the viable myocardium were subjected to perfusion scintigraphy of the myocardium with (99)mTc-technitrile («Diamed¼, Russia) at rest and in a combination with the nitroglycerine test, as well as metabolic scintigraphy of the myocardium with (123)I-labelled beta-methyl-ρ-iodophenyl pentadecanic acid (BMIPP). RESULTS: the studies showed that sensitivity of myocardial scintigraphy with (99)mTc-technitrile on the background of the nitroglycerine test amounted to 89%, with specificity of 85% and diagnostic accuracy of 86%. While calculating the diagnostic significance of SPECT with (123)I-BMIPP, in turned out that the method's sensitivity amounted to 94%, specificity to 87%, and diagnostic accuracy to 91%. CONCLUSION: perfusion scintigraphy of the myocardium on the background of the nitroglycerine test and scintigraphic assessment of metabolism of fatty acids are highly informative tests for revealing viable portions of the ischemic myocardium, with the diagnostic parameters of SPECT with (123)I-BMIPP being slightly superior to those of perfusion scintigraphy with (99)mTc-technitrile on the background of sublingual administration of nitroglycerine.

[Cardiovascular effects of D-ALA2, LEU5, ARG6-enkephalin (dalargin) are mediated by peripheral mu-opioid receptor activation].

It has been established that intravenous administration of dalargin at a dose of 0.1 mg/kg induced hypotensive, positive inotropic, and positive chronotropic response in patients with myocardial infarction, while not producing the "steal syndrome." The positive chronotropic effect of dalargin was mediated by peripheral mu-opioid receptors. Increase in the heart rate induced by dalargin had a reflex nature. Direct action of dalargin on the heart was accompanied by a decrease in the heart rate and a delay in the cardiac conductance in the atrioventricular junction region.

[Gamma-scintigraphy in assessment cardioresynchronizing therapy at chronic heart failure].

The purpose of the work was to study influence of cardioresynchronizing therapy (CRT) on systolic and diastolic myocardial function with the aid of radionuclide methods. 19 patients (9 women) at the age from 21 to 72 years (average age 55.4 +/- 8.3 years) with NYHA class III - IV cardiac insufficiency, dilated cardiomyopathy (n = 14) and ischemic cardiomyopathy (n = 5) were included in the study. Radionuclide angiopulmonography and balanced radionuclide ventriculography were performed by standard method before CRT, in 20 - 30 days and in 12 - 18 months. In 20 - 30 days after CRT significant increase in stroke volume and stroke index, ejection fraction and part of circular fibers contraction was detected, which confirmed improve in systolic heart function. In 12 - 18 months significant increase in maximal filling rate index, filling fraction of 1/3 and 2/3 of diastole was noted, which reflected improve of left ventricle diastolic function. Recovery of myocardial contraction synchronism leaded to rehabilitation of normal pulmonary microcirculation. Radionuclide examination methods as high-informative modes of combine assessment of heart contractile function and pulmonary circulation in CRT dynamics are described. CRT, improving systolic and diastolic myocardial functions, has positive influence on pulmonary hemodynamics in patients with chronic heart failure.

[Possibilities of overcoming difficulties in the differential diagnosis of nonmassive pulmonary thromboembolism in patients taken to the hospital by ambulance].

AIM: To optimize the differential diagnosis of nonmassive pulmonary thromboembolism (PTE) in patients emergently admitted to a multidisciplinary hospital. MATERIALS AND METHODS: The study enrolled 36 patients with nonmassive PTE and 28 with community-acquired pneumonias (ACP). All the patients underwent a comprehensive study, including primarily a clinical study in order to search for the early clinical manifestations of PTE. Ventilation-perfusion lung scintigraphy (VPLS) was performed in 11 patients with nonmassive PTE, 28 with ACP, and 10 healthy volunteers. RESULTS: The initial diagnosis of ACP was established in 26 of the 36 emergently hospitalized patients. Most early clinical manifestations of PTE and A CP were similar; their distinguishing features suggested that there might be nonmassive PTE. It is suggested that VPLS should be used for differential diagnosis in the above cases, by additionally assessing alveolar-capillary permeability. Twenty-eight patients with ACP were found to have a pronounced and significant acceleration of alveolar-capillary permeability in the affected lung at minutes 10 [23.5 +/- 1.9% (versus 8.02 +/- 3.89% in 11 patients with nonmassive PTE; p = 0.01)] and 30 of the study [33.4 +/- 1.9% (versus 13.64 +/- 4.0% in nonmassive PTE; p = 0.004)] while in nonmassive PTE, alveolar-capillary permeability corresponded to the values typical of healthy individuals, without exceeding 12 and 22% at minutes 10 and 30 of the study, respectively. CONCLUSION: VPLS makes it possible to verify or exclude the thromboembolic nature of pulmonary perfusion disorders. If it is difficult to make a diagnosis in the presence of the clinical symptoms characteristic of both nonmassive PTE and ACE, VPLS with an additional assessment of alveolar-capillary permeability, ACP substantially increases the accuracy of differential diagnosis of nonmassive PTE and ACE.

[Scintigaraphic assessment of viability of the ischemic myocardium while carrying out nitroglycerine-mediated and orthostatic tests].

The work deals with diagnostic possibilities of single photon emission computed tomography (SPECT) of the heart and ECG-synchronized planar scintigraphy (ECG-PS) with 99mTc-tetrophosmine used to determine viability of the ischaemic myocardium in patients presenting with postmyocardium infarction cardiosclerosis. A total of 20 patients diagnosed with Ischaemic heart disease (IHD), functional class III-IV angina of effort, postmyocardium infarction cardiosclerosis were examined. All the patients underwent SPECT of the heart with 99mTc-tetrophosmine, which was carried out at rest and on the background of sublingual administration of nitroglycerine, as well as planar ECG-synchronized scintigraphy of the myocardium according to the protocol: rest - nitroglycerine-mediated - orthostatic tests. Repeat examinations at rest were performed 4-6 weeks after the coronary artery bypass (CAB). The obtained findings showed that sensitivity of perfusion SPECT with 99mTc-tetrophosmine of the myocardium amounted to 85%, specificity to 76%, and diagnostic accuracy to 82%. Calculating the diagnostic parameters of perfusion while using ECG-PS with sublingual administration of nitroglycerine demonstrated that sensitivity of the method amounted to 71%, specificity to 91%, and diagnostic accuracy to 83%. Analyzing the orthostatic test yielded sensitivity equalling 72%, specificity - 84% and diagnostic accuracy - 81%. Sensitivity of assessing myocardial contractility by means of ECG-PS using nitroglycerine amounted to 83%, with specificity of 86% and diagnostic accuracy of 85%. At the same time, sensitivity of the orthostatic test amounted to 80%, specificity to 92%, and diagnostic accuracy to 88%. Hence, carrying out SPECT and ECG-synchronized planar scintigraphy of the heart with 99mTc-tetrophosmine on the background of sublingual administration of nitroglycerine and the orthostatic test makes it possible to simultaneously assess the reserve of myocardial contractility and perfusion, thus strongly suggesting a high informative value of the techniques involved in detecting myocardial viability in patients with postmyocardium infarction cardiosclerosis.

Chronotropic effect of D-Ala2,Leu5,Arg6-enkephalin (dalargin) is associated with activation of peripheral kappa-opioid receptors.

Intravenous infusion of D-Ala2,Leu5,Arg6-enkephalin (dalargin) caused bradycardia in narcotized rats. This effect was not observed during opioid receptor blockade with naloxone, naloxone methiodide, and norbinaltorphimine. Dalargin and (-)-U-50,488 added to Krebs-Henseleit perfusion solution for isolated rat heart decreased heart rate. Ganglionic blocker hexamethonium potentiated the negative chronotropic effect of dalargin. The negative chronotropic effect of dalargin is probably associated with activation of cardiac kappa-opioid receptors. It should be noted that dalargin caused tachycardia in some animals. This reaction was not observed after treatment with hexamethonium. The positive chronotropic effect of dalargin is probably related to modulation of the parasympathetic autonomic nervous system. Agonists and antagonists of delta-opioid receptors caused persistent bradycardia. We hypothesized that selective delta-opioid antagonists exhibit properties of partial delta-receptor agonists.