A STUDY OF ENDOTHELIAL DYSFUNCTION IN PREDIABETICS AS EVIDENCED BY FLOW MEDIATED VASODILATION IN COLOR DOPPLER OF BRACHIAL ARTERY

Dr. T. Renuka and Dr. P. Rajendra ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History Received: 25 March 2020 Final Accepted: 30 April 2020 Published: May 2020 Endothelial dysfunction is an early event and it precedes atherosclerosis. Does endothelial functional assessment can provide valuable insight into "PRE-INTRUSIVE" phase of atherosclerosis . Flow mediated dilation is known to depend on ability of endothelium to release nitric oxide in response to shear stress and can be used to estimate reliably endothelial function."PRE-DIABETIC PATIENTS" have endothelial dysfunction due to HYPER GLYCAEMIA and INSULIN RESISTANCE. This study was under taken in pre diabetics to know the occurrence of endothelial dysfunction. Endothelial dysfunction was assessed Non Invasively by Doppler Ultrasound of brachial artery of pre diabetic patients who had impaired "Fasting Plasma Glucose". Flow mediated dilatation was calculated as percentage increase in brachial artery diameter in response to increase in brachial artery flow. The importance of unravelling mechanistic link between early insulin resistance and accelerated atherosclerosis is underscored by recent finding even in adolescents mild insulin resistance is associated with increased cardio vascular risk. Decreased nitric oxide bioavailability in endothelium is of particular relevance in pre-diabetics. This study was done with that hypothesis that insulin resistance is a substrate for accelerated atherosclerosis depicted by endothelial dysfunction. The findings in our study are that mild insulin resistance is associated with accelerated endothelial dysfunction.

Endothelial dysfunction is an early event and it precedes atherosclerosis. Does endothelial functional assessment can provide valuable insight into "PRE-INTRUSIVE" phase of atherosclerosis . Flow mediated dilation is known to depend on ability of endothelium to release nitric oxide in response to shear stress and can be used to estimate reliably endothelial function."PRE-DIABETIC PATIENTS" have endothelial dysfunction due to HYPER GLYCAEMIA and INSULIN RESISTANCE. This study was under taken in pre diabetics to know the occurrence of endothelial dysfunction. Endothelial dysfunction was assessed Non -Invasively by Doppler Ultrasound of brachial artery of pre diabetic patients who had impaired "Fasting Plasma Glucose". Flow mediated dilatation was calculated as percentage increase in brachial artery diameter in response to increase in brachial artery flow. The importance of unravelling mechanistic link between early insulin resistance and accelerated atherosclerosis is underscored by recent finding even in adolescents mild insulin resistance is associated with increased cardio vascular risk. Decreased nitric oxide bio-availability in endothelium is of particular relevance in pre-diabetics. This study was done with that hypothesis that insulin resistance is a substrate for accelerated atherosclerosis depicted by endothelial dysfunction. The findings in our study are that mild insulin resistance is associated with accelerated endothelial dysfunction. Modulation of vascular tone , regulation of vessel inflammation and inhibition of thrombosis is impaired in pre diabetes , creating a permissive environment for atherogenesis

Vasomotor function:
Increased production of reactive oxygen species , decreased (NO) nitric oxide bioavailability of endothelium -derived NO

Inflammation:
Insulin resistance increases inflammation , the "T" cells migrate to vascular intima. They secrete cytokines and chemokines recruiting monocytes and smooth muscle cells. Leading to fatty streaks.

Thrombosis:
Pre diabetic endothelial cells augment production of tissue factor , leading to thrombus formation.

Biomarkers of endothelial cell Dysfunction:
1. Elevated levels of plasma cellular adhesion molecules (E-selectin , I CAM 1 and V CAM 1) , it raises relative risk of CVD in pre diabetes and diabetes by 1.5 -7.5 fold.
"Assessment of flow mediated dilation in brachial artery by color Doppler Ultrasonography" The brachial artery flow mediated Doppler was performed in all subjects using 7.5MHz transducer. Test was done after overnight fasting. The B.P cuff was tied to the right arm in the supine position.
The Brachial artery was imaged in right cubital fossa and its diameter measured. (From intima media with electronic calipers) at end -systole. Systolic and diastolic velocity time integrals were measured. The arm was then occluded by raising pressure in BP cuff to atleast 50mm above the systolic pressure. The Systolic and Diastolic velocity time integrals were measured within 15 seconds of release of pressure in the cuff. The brachial artery diameter was measured again at 1 minute to assess the flow mediated dilation. The ultrasound of brachial artery was continuously recorded before , during and up to 2 minutes after release of occlusion.