Continuous central haemodynamic measurements during the six-minute walk test and daily life in patients with chronic heart failure
1 Department of Cardiology, Karolinska Institutet, S-171 76, Stockholm, Sweden
2 University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
3 Mid-America Heart Institute, Kansas City, MO, USA
4 University of Cologne, Cologne, Germany
5 Medtronic, Inc., Minneapolis, MN, USA
* Corresponding author. Tel: +46 8 51771629, Fax: +46 8 311044, Email: frieder.braunschweig{at}karolinska.se
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Abstract |
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Aims: To compare haemodynamic responses during the 6-min walk test (6MWT) and daily living activities in heart failure (HF) patients.
Methods and results: Eighteen HF patients received an implantable haemodynamic monitor, which continuously measured heart rate (HR), estimated pulmonary artery diastolic pressure (ePAD), and several right ventricular (RV) pressure parameters. During the 6MWT, haemodynamics were assessed at rest and peak exercise. Ambulatory values were measured as the daily minimum, maximum, and median, averaged over the 14-day period surrounding each 6MWT. During the 6MWT, HR increased from 71 ± 17 to 101 ± 20 b.p.m. and ePAD from 20 ± 5 to 34 ± 8 mmHg. Daily minimum values were significantly lower and daily maximum values higher compared with rest and peak exercise. Patients with a walked distance above the median (402 m) had lower resting HR (64 ± 10 vs. 77 ± 20, P = 0.001) and ePAD (18 ± 4 vs. 21 ± 7, P = 0.022) compared to patients with walked distances below the median; values at peak exercise were similar. This pattern was also observed during the ambulatory periods.
Conclusion: Ranges of HR and RV pressures are significantly larger during daily living activities compared with 6MWT in HF patients. Haemodynamic characteristics of patients with greater exercise capacity include lower resting HR and RV pressures and are similar during the 6MWT and daily life.
Key Words: Exercise • 6-min walk test • Haemodynamic monitoring • Congestive heart failure • Haemodynamics
Received December 12, 2008; Revised February 9, 2009; Accepted February 13, 2009