CARDIAC OUTPUT (Q) MEASUREMENT AT REST AND DURING RESISTANCE AND AEROBIC EXERCISE IN PATIENTS WITH COMPENSATED HEART FAILURE (CHF).
N.J. Goldman*, J.J. Collis, C.Cheetham, L.G. Dembo, A.J. Maiorana, D.J. Green, J.G.O'Driscoll.
Cardiac Transplant Unit, Royal Perth Hospital, Human Movement and Medicine, The University of Western Australia.
Background: The haemodynamic response to "aerobic" and "resistance" exercise modalities has not been well described in patients with CHF. We compared cardiac output (Q) and haemodynamic data recorded during two typical exercise training modalities.
METHODS: following right heart catheterisation, baseline data were recorded after a 30 min supine rest period in 10 CHF patients, NYHA III-IV. VO2 was continuously measured using indirect calorimetry. Two methods were used to simultaneously measure Q; continuous thermodilution (TD; Baxter VigilanceTM) and the Fick principle. Patients then performed leg extension exercise at 40% of maximum voluntary contraction (resistance exercise). After recovery, patients performed a cycle ergometer test of 3 min stages, beginning at 20 Watts with 20 Watt increments, to volitional exhaustion.
RESULTS: At rest, average Fick and thermodilution Q data were similar (4.2±0.6 vs 4.1±0.3 L/min; P=0.9, t-test), but not significantly correlated (r=0.2). in response to cycle ergometer exercise, Q increased to 7.6±0.6 (Fick) and 5.8±0.7 (TD) (P,0.05, t-test) during the resistance exercise, Q increased to 5.5±0.4 (Fick) and 5.3±0.2 (TD). Heart rate (P<0.001), SBP (P<0.01) and Q (P<0.01) were significantly higher during aerobic, compared to resistance exercise.
CONCLUSIONS: Using the Fick and thermodilution methods, Q did not differ significantly at rest, although this data was not highly correlated. This lack of association between measurements using the two methods was exacerbated during exercise. When aerobic and resistance exercise modalities were compared, BP, HR and Q responses were greater during continuous "aerobic" exercise. These results suggest that resistance exercise can be safely performed by patients with CHF.
