title: Enhanced external counterpulsation treatment improves arterial wall properties and wave reflection characteristics in patients with refractory angina.
abstract: OBJECTIVE
  To determine if arterial properties and wave reflection characteristics are favorably altered after enhanced external counterpulsation (EECP) treatment in patients with refractory angina.
  
  
  BACKGROUND
  Early return of reflected waves from the lower body, resulting from increased arterial stiffness, augments central aortic pressure and increases left ventricular (LV) afterload and myocardial oxygen demand. EECP acutely enhances coronary perfusion (supply) and reduces LV afterload (demand). However, the mechanisms responsible for the sustained beneficial effects of EECP treatment are unclear.
  
  
  METHODS
  Radial artery pressure waveforms were recorded by applanation tonometry and central aortic pressure waveforms generated using a mathematical transfer function in 20 patients with stable refractory angina. Data were collected before and after 34 1-h EECP sessions. Augmentation index (AI(a)) and timing of the reflected pressure wave were calculated from the aortic waveform.
  
  
  RESULTS
  EECP treatment caused a decline in AI(a) and an increase in reflected wave travel time. These modifications in wave reflection characteristics caused a decrease in aortic systolic pressure and wasted LV pressure energy. The average number of angina episodes and Canadian Cardiovascular Society (CCS) class, both decreased in concordance with the physiologic changes due to EECP treatment.
  
  
  CONCLUSIONS
  EECP treatment reduces arterial stiffness and improves wave reflection characteristics in patients with refractory angina. These changes decrease LV afterload and myocardial oxygen demand and reduce the number of angina episodes, therefore enabling patients to participate in continuous exercise programs which in turn may provide long-term benefits and sustained improved quality of life.
authors.affiliation: Department of Medicine/Cardiology, University of Florida College of Medicine, Gainesville, Florida 32610, USA. nichoww@medicine.ufl.edu
authors.forename: Wilmer W
authors.initials: WW
authors.lastname: Nichols
authors.forename: Juan C
authors.initials: JC
authors.lastname: Estrada
authors.forename: Randy W
authors.initials: RW
authors.lastname: Braith
authors.forename: Karen
authors.initials: K
authors.lastname: Owens
authors.forename: C Richard
authors.initials: CR
authors.lastname: Conti
mesh_terms: D000368:Aged; D000787:Angina Pectoris / Q000503:physiopathology* / Q000628:therapy*; D001011:Aorta / Q000503:physiopathology*; D001794:Blood Pressure; D015908:Counterpulsation / Q000379:methods*; D004548:Elasticity; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D011674:Pulse; D017534:Radial Artery / Q000503:physiopathology*; D012720:Severity of Illness Index; D013599:Systole; D016277:Ventricular Function, Left
chemical_list: D010100:Oxygen