Clinical cardiac structural anatomy reconstructed within the cardiac contour using multidetector-row computed tomography: Left ventricular outflow tract

The left ventricular outflow tract (LVOT) is a common site of idiopathic ventricular arrhythmia. Many electrocardiographic characteristics for predicting the origin of arrhythmia have been reported, and their prediction rates are clinically acceptable. Because these approaches are inductive, based on QRS-wave morphology during the arrhythmia and endocardial or epicardial pacing, three-dimensional anatomical accuracy in identifying the exact site of the catheter position is essential. However, fluoroscopic recognition and definition of the anatomy around the LVOT can vary among operators, and three-dimensional anatomical recognition within the cardiac contour is difficult because of the morphological complexity of the LVOT. Detailed knowledge about the three-dimensional fluoroscopic cardiac structural anatomy could help to reduce the need for contrast medium injection and radiation exposure, and to perform safe interventions. In this article, we present a series of structural images of the LVOT reconstructed in combination with the cardiac contour using multidetector-row computed tomography. We also discuss the clinical implications of these findings based on the accumulated insights of research pioneers.

A Comparison of Quantitative T2 Mapping on Cardiovascular Magnetic Resonance Imaging with Metaiodobenzylguanidine Scintigraphy and Left Ventricular Functional Recovery in Dilated Cardiomyopathy: A Retrospective Pilot Study

OBJECTIVE

Metaiodobenzylguanidine (MIBG) scintigraphy is used to assess heart failure (HF) severity and to predict cardiac functional recovery. Cardiovascular magnetic resonance (CMR) imaging has recently been used to diagnosis HF. We evaluated CMR T2 mapping and MIBG scintigraphy in dilated cardiomyopathy (DCM) patients.

METHODS

Consecutively, 22 DCM patients [aged 56.8 ± 13.4 years; 6 women and 16 men; left ventricular ejection fraction (LVEF), 31.9 ± 10.7%] who underwent T2 mapping and MIBG scintigraphy were retrospectively evaluated. Echocardiography results were recorded at baseline and the 6-month follow-up. Patients with an increased LVEF ≥15% between the 2 measures were considered to be responders. We measured each patient's T2 values and MIBG indices [the heart-to-mediastinum ratio (H/M) in the early phase, H/M in the delayed phase, and the washout rate (WOR)] at baseline. We compared these values between the 12 responders and 10 non-responders.

RESULTS

The mean T2 value for all patients was 64.5 ± 6.6 ms. The mean values of early H/M, delayed H/M, and WOR were 2.06 ± 0.25, 1.94 ± 0.35, and 43.5 ± 11.8%, respectively. The T2 values were found to correlate with MIBG indices (p<0.05 for all) and were lower in the responders than non-responders (61.4 vs. 68.1 ms, p=0.013). MIBG indices were not significantly different.

CONCLUSION

Our study shows that the T2 values correlated with the MIBG indices and were increased in non-responders. T2 mapping may be useful in assessing the cardiac function and functional recovery in DCM patients.

Relationship of decreased accumulation of (99m)Tc-tetrofosmin on myocardial single-photon emission computed tomography images between QRS duration in dilated cardiomyopathy patient with left bundle branch block

PURPOSE

This study aimed to clarify the relationship between severity of conduction delay in the left ventricle and myocardial uptake of (99m)Tc-tetrofosmin (TF) in dilated cardiomyopathy (DCM) patients with left bundle branch block (LBBB).

METHODS AND RESULTS

Thirty-two DCM patients with LBBB underwent electrocardiography and (99m)Tc-TF myocardial single-photon emission computed tomography (SPECT). SPECT images were acquired at 30 min (early images) and 3 h (late images) after injection. We calculated the total defect score (TDS) using a 20-segment model with a 5-point scoring system. The TDS in early and late images was defined as the summed early score (SES) and summed late score (SLS), respectively. On early images, 29 of 32 patients (91%) had decreased tracer uptake in the septum. All patients showed a decreased tracer uptake in the septum on late images. A significant correlation was observed between TDS (both SES and SLS) and QRS duration, with SLS showing an excellent correlation (SES: r = 0.554, P < 0.001; SLS: r = 0.779, P < 0.0001).

CONCLUSIONS

These findings suggest that in DCM patients with LBBB, hypoperfusion and myocardial damage in the septum might occur in accordance with an increase in the QRS duration.

Vascular remodeling in hypertensive transgenic mice

We physiologically and histopathologically analyzed vascular damage due to hypertension and vascular remodeling in hypertensive transgenic mice (Tsukuba hypertensive mice; THM). Pubertal (6-week-old) THM already had hypertension similar to blood pressure in adult THM due to an enhanced renin angiotensin system (RAS). They progressively developed remarkable vascular hypertrophy composed of dedifferentiation of vascular smooth muscle cells (VSMCs) and extracellular matrix accumulation in the thoracic aorta, and VSMC hyperplasia was predominant in the abdominal aorta. THM are therefore a useful animal model for studying vascular remodeling mediated by enhanced RAS.