MR fluoroscopy in vascular and cardiac interventions (review)

Vascular and cardiac disease remains a leading cause of morbidity and mortality in developed and emerging countries. Vascular and cardiac interventions require extensive fluoroscopic guidance to navigate endovascular catheters. X-ray fluoroscopy is considered the current modality for real time imaging. It provides excellent spatial and temporal resolution, but is limited by exposure of patients and staff to ionizing radiation, poor soft tissue characterization and lack of quantitative physiologic information. MR fluoroscopy has been introduced with substantial progress during the last decade. Clinical and experimental studies performed under MR fluoroscopy have indicated the suitability of this modality for: delivery of ASD closure, aortic valves, and endovascular stents (aortic, carotid, iliac, renal arteries, inferior vena cava). It aids in performing ablation, creation of hepatic shunts and local delivery of therapies. Development of more MR compatible equipment and devices will widen the applications of MR-guided procedures. At post-intervention, MR imaging aids in assessing the efficacy of therapies, success of interventions. It also provides information on vascular flow and cardiac morphology, function, perfusion and viability. MR fluoroscopy has the potential to form the basis for minimally invasive image–guided surgeries that offer improved patient management and cost effectiveness

LACTIC ACID IN THE BLOOD OF RESTING MAN

The conception that, under resting conditions, blood lactic acid varies directly with pH is now current in the literature. According to this view, in states of alkalosis, lactic acid increases in the blood while during acidosis the opposite effect is produced. The origin of this con-ception is chiefly attributable to the work of Macleod (1), Anrep and Cannan (2), Long (3), and Eggleton and Evans (4). A further commonly accepted view concerning lactic acid in the blood of resting man is that this substance originates chiefly from muscle metabolism. The gradual accumulation of data in our hands from various sources during the past few years with respect to lactic acid has led to the formulation of the following inquiry: To what extent are the generally accepted mechanisms mentioned above concerning lactic acid operable in man? An investiga-tion of these questions is desirable because much of the existing informa-tion has accrued from experimental work on cats and dogs. The present data have been obtained in a study of normal man unless otherwise stated