Perfusion Of Septum Research Articles

P6180Septal negative work correlates inversely with septal scar in patients referred for cardiac resynchronization therapy

Abstract Background Myocardial scar is frequently present in patients with heart failure and left bundle branch block (LBBB), and associated with reduced response to cardiac resynchronization therapy (CRT). Furthermore, LBBB may be associated with markedly reduced strain, work, metabolism and perfusion in septum, even without septal ischemia. Therefore, it may be challenging to identify scar by functional imaging methods. Purpose To investigate the ability of advanced echocardiographic and nuclear imaging techniques to detect septal and left ventricular (LV) lateral wall scar in patients referred for CRT, compared to late gadolinium enhancement (LGE) cardiac magnetic resonance. Methods Scar was quantified as percentage LGE in five septal and five LV lateral wall segments of 131 patients (age 66±10, 66% male, QRS-width 164±17ms) referred for CRT, 92% with LBBB. Longitudinal strain was assessed by speckle tracking echocardiography in 130 patients (652 septal and 631 LV lateral wall segments). Myocardial work was calculated by LV pressure-strain analysis. Systolic shortening defined positive work, while systolic lengthening defined negative work. Glucose metabolism was assessed by 18F-fluorodeoxyglucose (FDG) Positron Emission Tomography (PET) in 52 patients (260 septal and 260 LV lateral wall segments). Perfusion was assessed in 46 patients (230 septal and 230 LV lateral wall segments) by either 13N-ammonia PET (n=32) or Single Photon Emission Computed Tomography (SPECT) (n=14). Metabolism and perfusion were reported as percentages of the segment with maximum tracer uptake. We evaluated parameter relationship to scar with Spearman correlation (rs) and regression analysis. Results LGE was present in 198 septal (30%) and 136 LV lateral wall (21%) segments. In a multivariate regression model with negative work, metabolism, perfusion and peak strain, only the first three parameters showed a significant association with LGE percent in septum (p<0.001, p=0.022 and p<0.001, respectively), while peak strain did not (p=0.270). Negative work in septum correlated inversely with percentage septal LGE-uptake (rs=-0.33): increasing amount of scar was associated with less negative work (Figure). In the LV lateral wall, however, negative work did not shown a significant association with percentage LGE in univariate regression analysis (p=0.109). In a multivariate regression model positive work, metabolism and perfusion correlated with percentage LGE (p=0.049, p=0.008 and p<0.001), while peak strain did not (p=0.607). Two representative patients Conclusions Septal negative work correlates inversely with septal scar in patients referred for CRT. This finding is probably linked to LBBB, and may be explained by increased stiffness of scar tissue. Myocardial work, but not peak strain, reflects scar in the LV lateral wall. Future studies should explore the assessment of scar in the complete LV and how this relates to CRT response.

Injection studies of arterial supply of the interventricular septum of the dog: Relationship of vascular changes to atrioventricular conduction

Four groups of dog hearts were studied by corrosion injection procedures in an attempt to correlate atrioventricular conduction with perfusion of the septum. Group 1 (controls) consisted of 30 normal hearts injected to demonstrate the normal arterial blood supply of the interventricular septum. Group 2 consisted of 30 hearts of dogs sacrificed 24 or 48 hours following ligation of the anterior septal artery. A prolonged P-R interval was present in each dog; injection studies showed complete absence of arterial filling of the central septal area. Group 3 consisted of 5 hearts; these dogs were sacrificed at the time the P–R interval began to revert to the value prior to ligation of the anterior septal artery or had been prolonged for more than 7 days. Injection studies demonstrated some degree of retrograde collateral filling of the anterior septal artery. Group 4 consisted of 15 hearts in which the P–R interval had returned to the value prior to ligation of the anterior septal artery (4 to 8 weeks). Injection studies showed complete retrograde collateral filling of the anterior scptal artery and its branches. From these studies it appears that there is a definite correlation between changes in atrioventricular conduction and perfusion of the interventricular septum of the dog.