Alberto Righetti

Improvement in cardiac sympathetic nerve activity in responders to resynchronization therapy

AIMS To assess changes in cardiac adrenergic activity with cardiac resynchronization therapy (CRT), and to investigate whether these changes are related to improvement in left ventricular ejection fraction (LVEF). METHODS AND RESULTS Sixteen patients (13 males, age 66 +/- 7 years) were studied at baseline and after > or =6 months of CRT (mean follow-up 9.2 +/- 3.2 months). LVEF was assessed by nuclear angiography. Responders were defined as patients showing > or =5% absolute increase in LVEF + improvement in > or =1 NYHA class + absence of heart failure hospitalization. Cardiac sympathetic nerve activity was studied by (123)I-metaiodobenzyl-guanidine ((123)I-MIBG) scintigraphy. Responders (n = 8) showed lower (123)I-MIBG washout at follow-up when compared with non-responders (P = 0.002), indicating lower cardiac sympathetic nerve activity. The decrease in (123)I-MIBG washout at follow-up when compared with baseline was only seen in the responder group (P = 0.036). There was a moderate correlation between increase in LVEF and decrease in (123)I-MIBG washout (r = 0.52, P = 0.04). CONCLUSION CRT induces a reduction in cardiac sympathetic nerve activity in responders, that parallels an improvement in LVEF, whereas non-responders do not show any significant changes.

Inflow effect in first‐pass cardiac and renal MRI

To estimate the effect of the inflow effect on the arterial input function in vivo in cardiac and renal MR perfusion imaging using fast gradient echo (GRE) sequences and contrast media.

Measurement of Left Ventricular Ejection Fraction by Real Time 3D Echocardiography in Patients with Severe Systolic Dysfunction: Comparison with Radionuclide Angiography

Aim: Measurement of left ventricular ejection fraction (LVEF) using real time 3D echocardiography (3DE) has been performed in subjects with preserved or modestly reduced systolic function. Our aim was to evaluate this technique in the subset of patients with severe systolic dysfunction. Methods and results: Consecutive patients with LVEF less than 0.35 at two‐dimensional echocardiography were included. LVEF obtained by 3DE was compared to the value measured by radionuclide angiography (RNA). Real time full‐volume 3DE was performed, with offline semiautomated measurement of LVEF using dedicated software (Cardioview RT, Tomtec) by a single observer blinded to the results of RNA. A total of 50 patients were evaluated, of whom 38 (76%, 27 males, age 69 ± 13 years) had a 3DE of sufficient quality for analysis. LVEF for this group was 0.21 ± 0.07 using 3DE and 0.27 ± 0.08 using RNA. The agreement between the two techniques was rather poor (r = 0.49; P < 0.001; 95% limits of agreements of −0.20 to 0.09). Truncation of the apex was observed in 6 of 38 (16%) patients. Conclusion: In patients with severe systolic dysfunction, 3DE shows poor agreement for measurement of LVEF as compared to RNA. There may be underestimation of up to 20% in absolute terms by 3DE. Accordingly, the two methods are not interchangeable for the follow‐up of LV function. A limitation of 3DE may, at least in part, be related to the incomplete incorporation of the apical region into the pyramidal image sector in patients with dilated hearts. (Echocardiography 2010;27:58‐63)

Computer analysis of cardiac wall motion asynchrony

Digital image processing is emerging as an increasingly important modality in the evolution of different types of image acquisition and analysis in cardiology. It has become an integral element in the technologies that are being developped and explored. New mathematical concepts in the assessement of cardiac function have been applied to digital images of the heart. Among them, the measurement of temporal changes in regional wall motion of the heart using Fourier analysis led to a significant improvement in the detection of regional alterations in ventricular function. Several imaging modalities can benefit from this approach for the assessement of the temporal sequence of cardiac wall motion.

Radionuclide evaluation of right ventricular wall motion after surgery in tetralogy of Fallot

SummaryRegional wall motion patterns in tetralogy of Fallot and its postoperative modifications by electrical and hemodynamic factors were assessed by Fourier analysis of gated radionuclide angiograms in 24 studies performed in children after surgical correction of tetralogy of Fallot. The range of right ventricular (RV) phase angles (standard deviation of the peak [SDP] of RV) as well as the difference between RV and LV (ΔMPh) were used as indices of the synchronicity of wall motion and were correlated with RV apical electrical activation time determined by endocardial electrical mapping. Postoperative studies were divided into two groups according to apical activation: (a) those involving right bundle branch block (RBBB) (nine patients), and (b) those involving distal RBBB (15 patients). ΔMPh was longer in proximal than in distal RBBB. Best discrimination between the two groups was obtained with SDP of RV (proximal=24°±3°, and distal=17°±2°;p<0.0001). These results showed that the range of ventricular phases measured by the SD of the phase distribution of the right ventricle is a good index for distinguishing between proximal and distal RBBB after cardiac surgery.

Detection of cardiac wall motion asynchrony by computer analysis techniques

Digital image processing is emerging as an increasingly important modality in the evolution of different types of image acquisition and analysis in cardiology. It has become an integral element in the technologies that are being developped and explored. New mathematical concepts in the assessment of cardiac function have been applied to digital images of the heart. Among them, the measurement of temporal changes in regional wall motion of the heart using Fourier analysis led to a significant improvement in the detection of regional alterations of ventricular function. Several imaging modalities can benefit from this approach for the assessment of the temporal sequence of cardiac wall motion.

2133 Effect of the bolus size on the quantification of myocardial perfusion using MRI

Introduction A limitation of MRI for cardiac perfusion on routine clinical MR scanners is the trade-off between the temporal resolution and spatial coverage. Assuming that a higher contrast media dose and a slower injection rate allow lower sampling rate without a significant loss of precision in an one compartmental model, we performed a simulation study to compare two contrast injection strategies (wide and narrow bolus). The validity of the protocol was then demonstrated in patients with a history of myocardial infarction, using 201-Tl SPECT imaging as reference.