Ventricular constraint using the acorn cardiac support device reduces myocardial akinetic area in an ovine model of acute infarction.

BACKGROUND: Left ventricular remodeling secondary to acute myocardial infarction (AMI) is characterized by ventricular dilatation and regional akinesis. In this study, we investigated the effect of passive constraint on akinetic area development. METHODS AND RESULTS: The effect of passive constraint on akinetic area was investigated in 10 sheep using tissue-tagging magnetic resonance imaging (MRI). A baseline MRI study was followed by the creation of an anterior infarct. After 1 week, the animals received a second MRI study. A cardiac support device (CSD) was then placed over the epicardium in 5 sheep whereas the remaining animals served as controls. A terminal study was performed at the 2-month postinfarct in both groups. The akinetic area at 1-week postinfarct was similar in both groups. At the terminal time-point, the akinetic area in the control group was similar to the 1-week time-point whereas in the CSD group, the area of akinesis decreased (P=0.001). A comparison of the 2 groups at the terminal time-point demonstrates a significantly diminished area of akinesis in the CSD group (P=0.004). The relative area of akinesis followed a similar pattern. End-systolic and end-diastolic wall thickness was significantly greater in the CSD group at terminal (P=0.001). In addition, the minimum wall thickness was greater in the CSD group compared with the controls (P=0.04). CONCLUSIONS: Passive constraint reduced akinetic area development secondary to AMI. The attenuation of regional wall stress may prevent the incorporation of the border zone into the infarct, decreasing infarct size and providing a promising new therapy for patients after an AMI.

Optically measured microvascular blood flow contrast of malignant breast tumors.

Microvascular blood flow contrast is an important hemodynamic and metabolic parameter with potential to enhance in vivo breast cancer detection and therapy monitoring. Here we report on non-invasive line-scan measurements of malignant breast tumors with a hand-held optical probe in the remission geometry. The probe employs diffuse correlation spectroscopy (DCS), a near-infrared optical method that quantifies deep tissue microvascular blood flow. Tumor-to-normal perfusion ratios are derived from thirty-two human subjects. Mean (95% confidence interval) tumor-to-normal ratio using surrounding normal tissue was 2.25 (1.92-2.63); tumor-to-normal ratio using normal tissues at the corresponding tumor location in the contralateral breast was 2.27 (1.94-2.66), and using normal tissue in the contralateral breast was 2.27 (1.90-2.70). Thus, the mean tumor-to-normal ratios were significantly different from unity irrespective of the normal tissue chosen, implying that tumors have significantly higher blood flow than normal tissues. Therefore, the study demonstrates existence of breast cancer contrast in blood flow measured by DCS. The new, optically accessible cancer contrast holds potential for cancer detection and therapy monitoring applications, and it is likely to be especially useful when combined with diffuse optical spectroscopy/tomography.