ABSTRACT
OBJECTIVE: Assessment of myocardial function can be performed at higher noise levels than necessary for coronary arterial evaluation. We evaluated image quality and radiation exposure of a dose-conserving function-only acquisition vs retrospectively electrocardiogram(ECG)-gated coronary CTA with automatic tube current modulation. METHODS: Of 26 patients who underwent clinically indicated coronary CTA for coronary and function evaluation, 13 (Group I) underwent prospectively ECG-triggered coronary CTA, followed by low-dose retrospectively ECG-gated scan for function (128-slice dual-source, 80 kVp; reference tube current, 100 mA; 8-mm-thick multiplanar reformatted reconstructions) performed either immediately (n = 6) or after 5- to 10-min delay for infarct assessment (n = 7). 13 corresponding controls (Group II) underwent retrospectively ECG-gated protocols (automatic tube potential selection with CARE kV/CARE Dose 4D; Siemens Healthcare, Forchheim, Germany) with aggressive dose modulation. Image quality assessment was performed on the six Group I subjects who underwent early post-contrast dedicated function scan and corresponding controls. Radiation exposure was based on dose-length product. RESULTS: Contrast-to-noise ratio (CNR) was preserved throughout the cardiac cycle in Group I and varied according to dose modulation in Group II. Visual image quality indices were similar during end systole but were better in Group II at end diastole. Although the total radiation exposure was equivalent in Group I and Group II (284 vs 280 mGy cm), the median radiation exposure associated with only the dedicated function scan was 138 mGy cm (interquartile range, 116-203 mGy cm). CONCLUSION: A low-dose retrospective ECG-gated protocol permits assessment of myocardial function at a median radiation exposure of 138 mGy cm and offers more consistent multiphase CNR vs traditional ECG-modulation protocols. This is useful for pure functional evaluation or as an adjunct to single-phase scan modes. ADVANCES IN KNOWLEDGE: Radiation exposure can be limited with a tailored myocardial function CT protocol while maintaining preserved images.
Subject(s)
Cardiac-Gated Imaging Techniques/methods , Coronary Angiography/methods , Heart Diseases/diagnostic imaging , Tomography, X-Ray Computed/methods , Contrast Media , Electrocardiography , Feasibility Studies , Female , Heart Diseases/physiopathology , Humans , Male , Middle Aged , Prospective Studies , Radiation Dosage , Retrospective StudiesABSTRACT
OBJECTIVE: Patients surviving large transmural myocardial infarction (MI) are at risk for congestive heart failure with attendant alteration of ventricular geometry and scar remodeling. Altered Gi-2 alpha and Gs alpha protein expression may be involved in cardiac remodeling associated with heart failure, however their expression in scar tissue remains unclear. METHODS: MI was produced in Sprague-Dawley rats by ligation of the left coronary artery. Gi-2 alpha and Gs alpha protein concentration, localization and mRNA abundance were noted in surviving left ventricle remote to the infarct, in border and in scar tissues from 8 week post-MI hearts with moderate heart failure. RESULTS: We observed a 4.5- and 5.0-fold increase in immunoreactive Gi-2 alpha protein concentration occurs in the border and scar regions vs. control values, respectively, in 8-week post-MI rat hearts. Similarly, immunoreactive Gs alpha protein concentration was increased 3.4- and 8.2-fold, respectively, in these tissues vs. controls. Double-fluorescence labeling and phenotyping studies revealed that both Gi-2 alpha and Gs alpha proteins were localized to myofibroblasts in the infarct scar and to viable myocytes bordering the scar. Northern analysis revealed that the Gi-2 alpha/GAPDH ratio was increased in both viable and scar regions (1.24- and 1.85-fold respectively) from experimental hearts when compared to sham-operated control values when compared to noninfarcted left ventricle, the value of this ratio in scar tissue was elevated approximately 1.5 fold. The Gs alpha/GAPDH ratio was significantly increased (1.28-fold) only in the scar region vs. control. CONCLUSION: Our results indicate a marked increase in the expression of Gi-2 alpha and Gs alpha from myofibroblasts of the infarct scar as well as remnant myocytes bordering the scar in 8-week post-MI rat hearts. We suggest that these changes may be associated with ongoing remodeling in the infarct scar in chronic post-MI phase of this experimental model.
Subject(s)
GTP-Binding Proteins/metabolism , Heart Failure/metabolism , Myocardial Infarction/metabolism , Myocardium/metabolism , Analysis of Variance , Animals , Blotting, Northern , Blotting, Western , Fibroblasts/metabolism , Fibroblasts/pathology , Fluorescent Antibody Technique , GTP-Binding Protein alpha Subunits, Gi-Go/analysis , GTP-Binding Protein alpha Subunits, Gi-Go/genetics , GTP-Binding Protein alpha Subunits, Gi-Go/metabolism , GTP-Binding Protein alpha Subunits, Gs/analysis , GTP-Binding Protein alpha Subunits, Gs/genetics , GTP-Binding Protein alpha Subunits, Gs/metabolism , GTP-Binding Proteins/analysis , GTP-Binding Proteins/genetics , Gene Expression , Heart Failure/pathology , Male , Myocardial Infarction/pathology , Myocardium/pathology , RNA, Messenger/analysis , Rats , Rats, Sprague-DawleyABSTRACT
Propaphenone hydrochloride in an antiarrhythmic which belongs to class 1C. In recent years it has been widely used in clinical medicine, mainly in the treatment of hyperkinetic arrhythmia. Given the enormous quantity of the medication taken, the description of the case seemed opportune as well as that of the clinical manifestations and electrocardiographic modifications linked to the parmakinetic and electrophysiological characteristics.
