title: Initial experience with an implantable hemodynamic monitor.
abstract: BACKGROUND
  Measurement of intracardiac hemodynamic parameters has been limited to brief periods in the acute care setting. We developed and evaluated an implantable hemodynamic monitor that is capable of measuring chronic right ventricular oxygen saturation and pulmonary artery pressure.
  
  
  RESULTS
  The device consists of an electronic controller placed subcutaneously and two transvenous leads placed in the right ventricle (reflectance oximeter) and pulmonary artery (variable capacitance pressure sensor). Implantation was performed in 10 patients with severe left ventricular dysfunction. Average implant pulmonary artery pressures were systolic, 52 +/- 16 mm Hg; diastolic, 29 +/- 11 mm Hg; and mean, 40 +/- 12 mm Hg. The mean right ventricular oxygen saturation at implant was 51%. Provocative maneuvers, including postural changes, sublingual nitroglycerin, and bicycle exercise, demonstrated expected changes in measured oxygen saturation and pulmonary artery pressures over time. At follow-up of 0.5 to 15.5 months, there were no significant differences between pulmonary artery pressures or oxygen saturation values transmitted from the device and simultaneous measurement with balloon flotation catheters. Four of the pulmonary artery leads dislodged and three demonstrated sensor drift, whereas two of the oxygen saturation sensors failed. Four patients died and four received transplants. Pathological study did not demonstrate injury to the right ventricular outflow tract or pulmonic valve.
  
  
  CONCLUSIONS
  Chronic measurement of hemodynamic parameters in the outpatient setting with implantable sensor technology appears to be feasible. The devices are well tolerated without significant untoward effects, and the sensors generally function well over time, providing reliable information. Clinical usefulness remains to be established.
authors.affiliation: Department of Cardiology, University of Missouri-Kansas City School of Medicine, USA.
authors.forename: D M
authors.initials: DM
authors.lastname: Steinhaus
authors.forename: R
authors.initials: R
authors.lastname: Lemery
authors.forename: D R
authors.initials: DR
authors.lastname: Bresnahan
authors.forename: L
authors.initials: L
authors.lastname: Handlin
authors.forename: T
authors.initials: T
authors.lastname: Bennett
authors.forename: A
authors.initials: A
authors.lastname: Moore
authors.forename: D
authors.initials: D
authors.lastname: Cardinal
authors.forename: L
authors.initials: L
authors.lastname: Foley
authors.forename: R
authors.initials: R
authors.lastname: Levine
mesh_terms: D000328:Adult; D000368:Aged; D001794:Blood Pressure; D018660:Blood Pressure Monitoring, Ambulatory / Q000295:instrumentation; D005069:Evaluation Studies as Topic; D005080:Exercise Test; D005260:Female; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D018670:Monitoring, Ambulatory / Q000295:instrumentation*; D010100:Oxygen / Q000097:blood; D019736:Prostheses and Implants; D011651:Pulmonary Artery / Q000503:physiopathology; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology; D016278:Ventricular Function, Right
chemical_list: D010100:Oxygen