The Study On Hemodynamics Of Periphery Arteries In Hyperthyroidism With Doppler Ultrasound

Hyperthyroidism is a common clinic endocrine disease, inception rate reach to 0.5%, the key feature of hyperthyroidism is the increased thyroid hormones, which can due to high excitability and hypermetabolism in recirculating system, digestive system, nervous system, and so on. Hyperthyroidism shows a hyperdynamic circulation with increased cardiac output, heart rate, pulse pressure and blood pressure and decreased vascular peripheral resistance, there are some special severe symptoms ,such as atrial fibrillation, exertional dyspnoea or other sings and symptoms about heart failure, even thyrotoxic storm in some serious patients. In domestic and overseas, many scholars endeavor to study the changes about heart in hyperthyroidism uninterruptedly, including morphology, changes and mechanisms. At present, there are many study methods to cardiovascular system by ultrasound, including 2- dimensional, Doppler, and other methods, such as integral backscatter, velocity vector imaging, opacification and 3d imaging. It is reported that hyperthyroidism cardiac disease is attributed to enlarged cardiac atrium and ventricle, increasing valve orifice velocity and contraflow. It is a common phenomenon of widen pulmonary artery and pulmonary hypertension. Before hyperthyroidism cardiac disease, left ventricular function has been damaged.For periphery artery in hyperthyroidism, the changes on arteria thyreoidea are widen diameter and velocity. Some scholars examinedcerebral arteries using transcranial doppler sonography, and found that doppler frequency is tall and sharp during systolic phase, velocity and PI are increased and it showes tachycardia. However, It is rarely reported that what effects happened on other periphery arteries in hyperthyroidism.With doppler ultrasound we examine hemodynamics indexes of common carotid artery, internal carotid artery, external carotid artery, renal artery and brachial artery in 52 hyperthyroidism patients and 40 adult normal. The objective is to observe what changes happen on periphery artery hemodynamics in hyperthyroidism, why, and what significance in clinic.For those arteries, we choose some hemodynamics indexes in common Doppler ultrasound method:end-diastole vessel diameter (D),systolic phase blood flow velocity (Vs) and end-diastole blood flow velocity (Vd),resistent index (RI),pulsatility index (PI),systolic phase acceleration (AC) and accelerating time (AT).The results are hyperkinetic circulatory state in hyperthyroid patients, who own higher indexes in Vs, PI, AC than that of healthy adults. The index of AT is signifcently increasing in hyperthyroid on all target arteries except brachial artery, which showes some effects happen on hemodynamics with the increasing TH. The vessels from hyperthyroid show an increased endothelium-dependent responsi- veness that may be secondary to the shear-stress induced by the hyperdynamic circulation, and that may contribute to the reduced vascular resistance characteristic of this disease. Vascular endothelialcell can synthesize and release much more prostacyclin and some factors like EDRF, which can diastole vascular. Hyperthyroidism has been found to be associated with a greater number of capillary vessels in the muscles, and the increased capillary density may be accompanied by an increase in the number of resistance arterial vessels, which could reduce vascular resistance. Also, the local release of vasodilators in peripheral tissues as a consequence of the elevated tissue metabolism associated with hyperthyroidism could cause dilatation of the resistance vessels. All the changes result in the decrease peripheral vascular resistance. Then the system of rennin-angiotensin-aldosterone is activated. At the same time, TH induce erythropoietin secreting, which due to increased cardiac output, heart rate, systole function. By the mechanisms, TH affect the regulation of body fluids, arterial blood velocity, and accelerationdecreased estrogen receptorsThe emphasis on this trial is to observe the changes of peripheral vascular resistance. Old findings showed that peripheral vascular resistance was decreased in hyperthyroidism. But, we found that the response to vasoconstrictors can be reduced, unchanged or enhanced in different blood vessels, which is increasing in brain or renal arteries, and decreasing in superficial parts issue. That is No consensus has been reached concerning the vasoconstrictor response in hyperthyroidism, which was not reported by others trials. We supported that the view of peripheral vascular resistance decreasing in hyperthyroidism is about the whole systemic circulation, and there aresome differences for concrete tissue or organs, such as the increased resistance in brain or renal arteries, which is probably associated with a local circulation that is much more important than humoral regulation. The local circulation plays a role in increasing arteries resistance in some critical organs as a self-protection. Some vaso-excitor materials induce to arteries resistance increasing and priming volume decreasing, for maintaining the common function. But, in skins, muscles and superficial tissue, arteries resistance is decreasing for containing lots of blood, which was supported by our trial results. Because there is big blood volume in peripheral vessels of skins, muscles and superficial tissue, peripheral vascular resistance is decreasing for the whole organism.We find a new conclusion, which was not reported in old trials, that the change of peripheral vascular resistance is increasing for some concrete tissue and organs. Observing and analyzing the phenomenon, we provided some new materials for further understanding the changes of hemodynamics in hyperthyroidism, which is very important in knowing the effects of high TH level on the changes of hemodynamics and on organs functions deeply, and there are some instructional meanings on diagnosing and treating hyperthyroidism and complication.