99mTc-HFAPi imaging identifies early myocardial fibrosis in the hypertensive heart.

BACKGROUND: This study aimed to explore whether 99mTc-radiolabeled fibroblast activation protein inhibitor (99mTc-HFAPi) imaging can detect early myocardial fibrosis in the hypertensive heart. METHODS: In the experimental model, spontaneously hypertensive rats (SHRs) and age-matched Wistar Kyoto rats (WKYs) were randomly divided into three groups (8, 16, and 28 weeks). The animals underwent 99mTc-HFAPi imaging and echocardiography. Autoradiography and histological analyses were performed in the left ventricle. The mRNA and protein expression level of the fibroblast activation protein (FAP) and collagen I were measured using quantitative PCR and western blot. In the clinical investigation, a total of 106 patients with essential hypertension and 20 gender-matched healthy controls underwent 99mTc-HFAPi imaging and echocardiography. RESULTS: In-vivo and in-vitro autographic images demonstrated diffusely enhanced 99mTc-HFAPi uptake in the SHR heart starting at week 8, before irreversible collagen deposition. The mRNA and protein levels of FAP in SHRs began to increase from week 8, whereas changes in collagen I levels were not detected until week 28. In the clinical investigation, even in hypertensive patients with normal diastolic indicators, normal left ventricular geometry, and normal global longitudinal strain (GLS), the prevalence of increased 99mTc-HFAPi uptake reached 34, 41, and 20%, respectively, indicating that early fibrogenesis precedes structural and functional myocardial abnormalities. CONCLUSION: In hypertension, 99mTc-HFAPi imaging can detect early fibrotic process before myocardial functional and structural changes.

18F-fluorodeoxyglucose positron emission tomography/computed tomography imaging in atrial fibrillation: a pilot prospective study.

AIMS: This prospective study explored relevant factors and clinical significance of atrial 18F-fluorodeoxyglucose (FDG) uptake in patients with atrial fibrillation (AF). METHODS AND RESULTS: One hundred AF patients underwent baseline FDG imaging prior to radiofrequency catheter ablation (RFCA). Of those, 30 subjects underwent additional FDG imaging at 3 months post-RFCA. Voltage mapping of the left atrium was analysed as a voltage score. Patients who received RFCA were followed for 26 months (17-31 months) to assess recurrence. At baseline FDG imaging, 74% of patients with persistent AF (PsAF) and 24% of patients with paroxysmal AF showed increased atrial FDG uptake. The prevalence was higher in the right atrium (49%) than in the left atrium (15%, P < 0.001) or left atrial appendage (21%, P < 0.001). Multivariate analysis demonstrated that PsAF and elevated B-type natriuretic peptide (BNP) were related to enhanced right atrial (RA) activity, and increased epicardial adipose tissue (EAT) activity was predictive of left atrial (LA) activity. LA activity was inversely associated with voltage score, while increased FDG uptake in the right atrium was predictive of successful AF termination by RFCA. Atrial FDG activities decreased significantly post-RFCA, but none of the FDG parameters were predictive of AF recurrence. CONCLUSIONS: Enhanced RA activity was associated with elevated BNP level, whereas LA activity was related to the increased activity of EAT and inversely correlated with LA fibrosis. Increased RA activity was predictive of successful AF termination by RFCA in PsAF patients.

Recent developments in echocardiographic imaging.

PURPOSE OF REVIEW: This review provides an outline of recent applications related to the use of ultrasonography in various catheter-based procedures for the repair of many valvular abnormalities. RECENT FINDINGS: Percutaneous interventions are becoming a safe and effective therapeutic modality in the management of various valvular defects. The intrinsic ability of ultrasound to provide real-time accurate assessment of cardiac and valvular structural and functional abnormalities makes this modality distinctively useful in the execution of percutaneous valvular procedures and evaluation of their results.Clinical applications of myocardial deformation and cardiac mechanics have been investigated in an increasing number of clinical applications. Speckle tracking accurately measures myocardial deformation parameters and has been recently applied to the evaluation of mitral insufficiency mechanisms. SUMMARY: Recent developments in echocardiography are promoting this modality from its traditional role of diagnostic technique into one suitable for aiding in the execution of complex catheter-based procedures and for accurate monitoring of therapeutic response in many clinical settings.

Stress-induced QTc-interval shortening as an ancillary marker of ischemia in patients with complete left bundle branch block.

BACKGROUND: In patients with left bundle branch block (LBBB), ischemia-induced repolarization changes associated with QTc-interval shortening may be recorded during coronary angioplasty. We aimed to assess whether these repolarization changes may be predictive of severe coronary artery disease in patients with LBBB. METHODS: Fifty noninfarcted LBBB patients underwent dipyridamole stress test and coronary angiography for chest pain. To localize the site of ischemia, we considered four groups of conventional ECG leads (V1-V2-V3; V4-V5-V6; aVL-I; III-aVF-II), exploring the anteroseptal, lateral, high-lateral, and inferior left ventricular walls. ST-T changes and QTc intervals were estimated at rest and peak stress, lead by lead, in each group of leads and the fractional percentage difference between rest-stress QTc intervals ([DELTA]QTc) was calculated. A [DELTA]QTc greater than -10% was used to define significant QTc-interval shortening. Coronary stenosis of more than 70% and more than 90% were considered 'significant' and 'severe'. RESULTS: According to dipyridamole stress test response, two groups were identified: group I (35 patients) with dipyridamole-induced ischemia and group II (15 patients) without dipyridamole-induced ischemia. The wall motion score index at peak stress (compared with resting wall motion score index) was significantly higher in group I (1.98 +/- 0.13 vs. 1.28 +/- 0.08, P < 0.0001) than in group II (1.36 +/- 0.18 vs. 1.25 +/- 0.08, P = 0.296). The patients of group I showed a significant QTc-interval shortening ([DELTA]QTc = -16.9 +/- 3.9%), whereas this did not happen in patients of group II ([DELTA]QTc = +8.8 +/- 2.4%, P < 0.0001). The patients of group I also had a more severe stenosis in the vessel related to the stress-induced dyssynergic area (I = 90.5 +/- 9.5 vs. II = 34.3 +/- 31.1%; P < 0.0001). CONCLUSION: In patients with LBBB, stress-induced pseudonormalization pattern, associated with QTc-interval shortening, allows the identification of cardiac areas supplied by severely stenosed coronary arteries.

Assessing the pattern of ST-segment depression during subendocardial ischemia using a computer simulation of the ventricular electrogram.

UNLABELLED: The primary aim of the study was to write a simple educational personal computer (PC)-based program able to simulate normal and pathological electrogram (EG) to analyze the ST-segment and T-wave patterns during subendocardial ischemia. BACKGROUND: The EG waveforms are know to depend on the properties of transmembrane action potentials (APs) of atrial and ventricular myocytes, the spread of excitation, and the characteristics of the volume conductor. Transmembrane AP is an electromotive generator that plays a central role, and it is the principal responsible for the potential differences that are recorded as an EG. The EG can be considered as the algebric sum of 2 transmembrane APs, that is, the AP of the underlying endocardial region minus the AP of the underlying epicardial region. METHODS: Using an educational PC software (Microsoft Excel), a normal EG was simulated reproducing planimetrically, point-by-point, normal transmembrane APs recorded from the epicardial and endocardial regions in normal animals. The shape and the voltage of the APs were then modified to closely mimic human APs. To simulate typical subendocardial ischemia, we changed the subendocardial AP according to experimental and clinical observations. RESULTS: The reconstruction of EG by the algebric subtraction (endocardial minus epicardial) APs was possible. The EG, mirroring typical subendocardial ischemia, was simulated without changing the epicardial AP. The EG simulating typical subendocardial ischemia showed a horizontal pattern of ST segment depression. In our model modification of the subendocardial AP combined with "unnatural" changes of the phase 3 of the subendocardial AP produced a downsloping pattern of ST-segment depression. CONCLUSION: The derivated EG waveform obtained with our PC program properly describe the algebric sum of endocardial and epicardial APs. In our opinion, this method represents a useful tool for the study of the AP changes. The simulated ST-depression morphology during subendocardial ischemia appears to be essentially "horizontal" and not downsloping. On the basis of our simplified theoretical model, we propose that ischemia-induced downsloping ST depression should be considered a reciprocal EG change and a manifestation of transmural ischemia in the wall opposite the exploring electrode.

Clinical utility of intraprocedural transesophageal echocardiography during transvenous lead extraction.

BACKGROUND: Transvenous lead extraction carries a risk of significant complications. Although intraoperative transesophageal echocardiography (TEE) is widely used to monitor cardiac performance and structures, its utility during transvenous lead extraction has not been well described. OBJECTIVE: This study evaluates the utility of TEE during transvenous lead extraction. METHODS: The records of 108 consecutive patients who underwent transvenous lead extraction with TEE guidance were reviewed. RESULTS: Transvenous extraction of 202 leads was attempted; complete extraction was achieved for 174 leads (86%) and partial extraction for 13 leads with clinically acceptable outcomes in 187 leads (93%). Mean age of the patients was 63 +/- 21 (14-99) years and 37% were female. The average number of leads per patient was 1.9 (1-6). Mean implant duration was 71 +/- 57 (1-360) months. Indications for extraction were pocket infection (53 patients), bacteremia (33), atrial J-lead fracture or recall (13), lead malfunction (8), and venous thrombosis (1). TEE identified critical findings that prompted emergency surgical intervention or converted transvenous lead extraction to surgical explantation in 6 patients (two cases with cardiac laceration, 3 cases of cardiac tamponade, and one case with a large vegetation and a patent foramen ovale). TEE eliminated the need for the premature termination of the procedure in 11 patients by excluding significant structural cardiac damage. Overall, TEE provided clinically useful information during transvenous lead extraction in 17 cases (16%). CONCLUSIONS: TEE during transvenous lead extraction provides valuable real-time information that improves efficacy and safety.

Stress radionuclide myocardial perfusion imaging detects more residual ischemia than stress echocardiography following acute myocardial infarction.

OBJECTIVES: This investigation sought to compare the abilities of stress radionuclide myocardial perfusion imaging and stress echocardiography to detect residual ischemia in patients following acute myocardial infarction (MI). BACKGROUND: Stress radionuclide myocardial perfusion imaging and stress echocardiography are both commonly used to assess patients (patients.) in the immediate post MI period. However, the relative value of these techniques in identifying post MI ischemia remains unclear. METHODS: Eighteen patients. underwent both dipyridamole radionuclide perfusion imaging and dobutamine stress echocardiography on the same day or on consecutive days, 3-7 days following uncomplicated acute MI. Pts. who had an acute percutaneous intervention were excluded. Images were reviewed with clinical information available, but blinded to the opposing modality, for perfusion defects, wall motion abnormalities (WMA), and evidence of ischemia (reversible defect(s) on perfusion imaging, worsening WMA on stress echocardiography). Of the 18 patients, 11 subsequently underwent cardiac catheterization. RESULTS: Perfusion imaging identified defects in 16 (89%) patients, of whom 15 (83% of total) were found to be ischemic. Stress echocardiography identified a fixed wall motion abnormality in 17 (94%) and ischemia in 8 (44%, p < 0.05 compared with perfusion imaging ischemia). Among 11 patients who underwent catheterization, there was a trend towards perfusion imaging identifying more ischemia in the territory of an obstructed (> or = 70%) vessel--100% (11/11) vs. 64% (7/11) for stress echocardiography (p = 0.09). CONCLUSION: In the immediate post-infarction period, dipyridamole stress radionuclide myocardial perfusion imaging more often shows evidence of residual ischemia than dobutamine stress echocardiography.

Cross-sectional multiplane transesophageal echocardiographic measurements: comparison with standard transthoracic values obtained in the same setting.

BACKGROUND: Several algorithms developed for cost-effective use of transesophageal echocardiography (TEE) propose elimination of "screening" transthoracic echocardiographic (TTE) studies. Cross-sectional measurements obtained by TTE (left atrial diameter [LAD], left ventricular internal dimensions in diastole and systole [LVIDd, LVIDs], septal and posterior wall thickness in diastole [VSTd, PWTd], LV end-diastolic and end-systolic volumes [LVEDV and LVESV], and LV ejection fraction [LVEF]) have not been standardized for TEE. METHODS: Forty-six patients (age 27 to 85 years, 60 +/- 13 years, 25 [54%] women) underwent TEE and TTE studies. TTE was performed while the TEE probe was in place and the patient was still sedated. Standard TTE measurements were compared with corresponding TEE values obtained from mid-esophageal and transgastric views. RESULTS: Standard TTE measurements compared favorably with those obtained by TEE at the mid-esophageal three-chamber view for LAD (3.9 +/- 0.6 cm vs 4.0 +/- 0.7 cm, P = NS) and at the transgastric long-axis view for LVIDd (4.6 +/- 0.8 cm vs 4.7 +/- 0.8 cm, P = NS), LVIDs (3.1 +/- 0.9 cm vs 3.1 +/- 0.9 cm, P = NS), and VSTd (0.95 +/- 0.18 cm vs 0.98 +/- 0.19 cm, P = NS). Biplane TTE and TEE measurements of LVEDV (106 +/- 35 ml vs 112 +/- 38 ml, P = NS), LVESV (37 +/- 23 ml vs 37 +/- 25 ml, P = NS), and LVEF (67 +/- 14% vs 69 +/- 14%, P = NS) also correlated closely. The negative predictive values of TEE measurements for excluding abnormal LAD, LVIDd, VSTd, PWTd, and LVEF as defined by TTE were 83%, 94%, 95%, 97%, and 97%, respectively. CONCLUSION: Cross-sectional TEE measurements as obtained in this study are equivalent to standard TTE dimensions and provide reliable information that may facilitate interpretation of TEE studies in the absence of TTE information.