Atherosclerosis

Background

arly Stage squareAtherosclerosis, sometimes referred to as “hardening of the arteries,” is a chronic inflammatory process that results in plaque being deposited in the walls of arteries. These plaques are composed of mainly cholesterol, immune cells, smooth muscle, and eventually calcium. As atherosclerosis progresses and plaque progressively narrows the arteries, some patients may experience chest pain related to decreased blood flow to the heart. Although atherosclerosis can be asymptomatic for decades, these plaques are prone to rupture, causing blood clots in the arteries that are capable of blocking blood flow to vital organs, causing death of tissue within minutes. The clinical manifestations of atherosclerosis depend on which regions of the vascular system are affected. For instance, atherosclerosis of the arteries supplying the heart commonly causes myocardial infarction (heart attack), and atherosclerosis of the arteries supplying the brain leads to strokes.

Risk factors for developing atherosclerosis include elevated LDL cholesterol, high blood pressure, tobacco smoking, and diabetes mellitus, along with advanced age, male gender and heredity. It is currently the leading cause of mortality and morbidity in the developed world and is predicted to become the leading global killer by the year 2020.

Current Treatment

The treatment of atherosclerosis focuses on both the prevention and pharmaceutical management of modifiable risk factors, such as elevated cholesterol, hypertension and diabetes. Lifestyle modifications, such as increased physical activity, weight loss, dietary improvements, and smoking cessation are also of great importance in reducing the risk of adverse outcomes. Medications that are currently used in the treatment of atherosclerosis include, but are not limited to:

  • Lipid altering therapy: Lowers serum cholesterol to slow the progression of atherosclerotic plaque
  • Anti-hypertensive therapy: Improves blood pressure levels
  • Anti-platelet Agents: Prevents the formation of blood clots

In some patients with advanced, life-threatening atherosclerotic disease or in those who have had an acute episode, revascularization procedures are warranted. These procedures may include stents and by-pass surgery that restore normal blood flow to the affected tissue.

Interventional Revascularization: Angioplasty and Stents 
Angioplasty is the technique of mechanically widening the obstructed arteries. A deflated balloon on a guide-wire (a balloon catheter) is advanced into the occluded vessel and inflated. Once the vessel is expanded, the balloon is deflated and withdrawn so that blood flow can be restored. At this time, a stent may be inserted to ensure that the vessel remains open, as angioplasty alone has a higher incidence of re-occlusion of the vessel.

Conventional Surgery: Grafting and Bypass
Coronary artery bypass graft surgery (CABG) is a surgical procedure in which arteries or veins (grafts) from other locations in the patient’s body are attached to the coronary arteries to allow blood flow to bypass obstructed regions caused by atherosclerosis. It is one of the most common procedures performed in U.S. hospitals and has a similar rate of success as balloon angioplasty with stenting (see above) but may be more beneficial if multi-vessel coronary disease is present.

Focused Ultrasound Research

The use of focused ultrasound is being explored in preclinical research to liquefy blood clots, either independently or in combination with bubbles and anti-clotting agents. Researchers have shown that ultrasound energy can cause vibrations that either break apart the clot or make it more easily treated with thrombolytic therapy. Ideally, this would allow for the reperfusion of occluded blood vessels that developed due to plaque rupture in atherosclerosis. While these preliminary results are exciting and early work is occuring in peripheral arteries, more research is needed to establish the safety and efficacy of FUS for thrombolysis in humans.

Notable Papers

Almekkaway MK, Shehata IA, Ebbini ES. Anatomical-based model for simulation of HIFU-induced lesions in atherosclerotic plaques. Int J Hyperthermia. 2015 Jun;31(4):433-42. doi: 10.3109/02656736.2015.1018966.

Xu S, Zong Y, Feng Y, Liu R, Liu X, Hu Y, Han S, Wan M. Dependence of pulsed focused ultrasound induced thrombolysis on duty cycle and cavitation bubble size distribution. Ultrason Sonochem. 2014 Jul 9. pii: S1350-4177(14)00227-2. doi: 10.1016/j.ultsonch.2014.06.024.

Hölscher T, Ahadi G, Fisher D, Zadicario E, Voie A. MR-guided focused ultrasound for acute stroke: a rabbit model. Stroke. 2013 Jun;44(6 Supp 1):S58-60.

Lapchak PA, Kikuchi K, Butte P, Hölscher T. Development of transcranial sonothrombolysis as an alternative stroke therapy: incremental scientific advances toward overcoming substantial barriers. Expert Rev Med Devices. 2013 Mar;10(2):201-13.

Click here for additional references from PubMed. 

     

Share this page