PubMed · 13274297
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J E RHOADS, W S VAUN, W M PARKINS, M BEN, H M VARS. 1955. Shock.. https://doi.org/10.1016/s0039-6109(16)34732-6
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BACKGROUND: Neovasculature within atherosclerotic plaques is believed to be associated with infiltration of inflammatory cells and plaque destabilization. The aim of the present investigation was to determine whether the amount of neovasculature present in advanced carotid plaques can be noninvasively measured by dynamic, contrast-enhanced MRI. METHODS AND RESULTS: A total of 20 consecutive patients scheduled for carotid endarterectomy were recruited to participate in an MRI study. Images were obtained at 15-second intervals, and a gadolinium contrast agent was injected coincident with the second of 10 images in the sequence. The resulting image intensity within the plaque was tracked over time, and a kinetic model was used to estimate the fractional blood volume. For validation, matched sections from subsequent endarterectomy were stained with ULEX and CD-31 antibody to highlight microvessels. Finally, all microvessels within the matched sections were identified, and their total area was computed as a fraction of the plaque area. Results were obtained from 16 participants, which showed fractional blood volumes ranging from 2% to 41%. These levels were significantly higher than the histological measurements of fractional vascular area. Nevertheless, the 2 measurements were highly correlated, with a correlation coefficient of 0.80 (P<0.001). CONCLUSIONS: Dynamic contrast-enhanced MRI provides an indication of the extent of neovasculature within carotid atherosclerotic plaque. MRI therefore provides a means for prospectively studying the link between neovasculature and plaque vulnerability.
Cardiovascular alterations during pregnancy are characterized by an increased vascular volume, cardiac output, and heart rate, with a marked fall in vascular resistance. Cardiac output is about 40-50% higher during the third trimester. Even higher values of cardiac output are observed during uterine contractions in labor. In general, arterial blood pressure remains unaffected or demonstrates some tendency toward lower diastolic pressure. The higher blood volume is associated with a slight increase in left ventricular dimensions. Left ventricular contraction force and its first derivative remain unchanged. Many symptoms and findings during pregnancy are caused by the described changes, such as dyspnea on exertion, presyncope due to pressure on the inferior vena cava resulting in a decreased venous return to the heart, prominent jugular venous pulsation, leg edema, and ejection murmurs over the aorta and pulmonary artery. Paroxysmal nocturnal dyspnea, anginal chest pain, syncopy, anasarca, and diastolic heart murmurs require further evaluation.