Quantitation of left ventricular asynchrony on radionuclide angiography phase images

Assessment of cardiac asynchrony by radionuclide phase analysis: correlation with ventricular function in patients with narrow or prolonged QRS interval

BACKGROUND

Conflicting data exist on the relation between the synchronism of cardiac contraction and ventricular function.

AIM AND METHODS

A resting radionuclide ventriculography (RNV) was performed in 380 consecutive patients to evaluate the relationship between the synchronism of cardiac contraction and ventricular function.

RESULTS

A significant, non-linear, relation was found between LVEF and intra-ventricular asynchrony or QRS, but not between inter-ventricular asynchrony and LVEF. A linear correlation was observed between QRS and intra-ventricular or inter-ventricular asynchrony. Intra-ventricular asynchrony was identified as the major, independent, determinant of LV function. With the increase in QRS duration, a decrease in LVEF (p<0.001), and a worsening of either intra-ventricular (p<0.001) or inter-ventricular synchronism (p<0.05), was documented. However, 48% of patients with QRS 120-150 ms had abnormal inter-ventricular and 42% abnormal intra-ventricular synchronism, while 27% of patients with QRS>150 ms had normal inter-ventricular and 25% normal intra-ventricular synchronism.

CONCLUSIONS

Intra-ventricular asynchrony was identified as the major determinant of ventricular dysfunction. A consistent proportion of patients had asynchrony despite preserved QRS duration or normal synchronism with a QRS>150 ms. Fourier phase analysis of RNV may detect asynchrony better than QRS. The role of RNV for detection of individual patients who may most benefit from resynchronization therapy requires additional investigations.

Heterogeneity of myocardial wall motion and thickening in the left ventricle evaluated with quantitative gated SPECT

BACKGROUND

Global and regional ventricular function may be evaluated by using gated myocardial perfusion single photon emission computed tomography (SPECT). This study investigated two parameters of regional contraction of the left ventricle, segmental wall motion (WM) and wall thickening (WT), to determine their similarity and disparity in each myocardial segment in patients with normal myocardial perfusion.

METHODS AND RESULTS

Thirty-five patients with normal myocardial perfusion and cardiac function (mean left ventricular ejection fraction, 62.6%+/-8.8%) were included in this study. A 1-day stress/rest protocol was used as a means of acquiring technetium 99m (Tc-99m) sestamibi gated SPECT protocol for each patient. A commercially available software package for quantitative gated SPECT (QGS) was used to generate cine loop three-dimensional surface display and SPECT images. The left ventricle was divided into 9 segments to score WM and WT (on a scale of 0 to 4, with 0 being normal and 4 being severely reduced) by 6 independent observers. The WM score was significantly higher than the WT score in the septum, whereas the WM score was lower than the WT score in the inferior segment. Similar WM and WT scores were observed in the remaining segments.

CONCLUSIONS

Heterogeneous myocardial WM and WT were observed by using QGS software. These findings suggest that different criteria are required in each segment to evaluate segmental WM and WT by means of gated myocardial perfusion SPECT.

Assessment of left ventricular regional function by radionuclide angiography: effects of number of sectors on repeatability

Twenty patients were studied by equilibrium radionuclide angiography (RNA) twice in the same day in order to assess the repeatability of quantitative measurements of left ventricular (LV) regional function by using a sector analysis method. RNA was performed in the best septal 45 degrees left anterior oblique projection, acquiring 150,000 counts/frame, at 20 msec/frame with 5% gate tolerance. LV regional analysis was performed using a computer algorithm written by the authors running on Digital PDP 11/34 machine. The algorithm after having identified the center of gravity of the LV, divided it into 4, 5 and 6 equiangular sectors. In the 5, and 6 sector analysis, the region including the mitral and aortic valves was excluded from subsequent analysis. In each sector Ejection Fraction (EF) and Peak Filling Rate (PFR) were computed. In addition, the Time to End Systole (TES) and Time to Peak Filling Rate were also assessed for each region. The coefficient of variation of the regional values of TES (CV-TES) and regional TPFR (CV-TPFR) were then computed and considered as indices of LV systolic (CV-TES) and diastolic (CV-TPFR) asynchrony. Repeatability was firstly assessed by linear regression analysis between the 2 RNA studies. Our data show a high correlation coefficient on regional values of EF and PFR (R: > 0.92). Moreover, the differences in a given parameter between the 2 studies were plotted against their mean value, and the coefficient of repeatability (CR) was calculated as twice the standard deviation of the differences. No significant differences were found between EF and PFR regional values in the 2 RNA studies (EF coefficient of repeatability: < 0.18; PFR coefficient of repeatability: < 0.8). A low value of coefficient of repeatability was found also for CV-TES (< 17) and for CV-TPFR (< 18). In conclusion LV regional analysis is a repeatable method of analysis, and the number of regions does not affect the repeatability.