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Haemodynamic changes during dobutamine stress echocardiography in patients with and without ischaemia
M B Mishra1, R A Cooke, G Jackson
1Department of Cardiology, Guy's and St Thomas' NHS Trust, London, UK.
Insights
Dobutamine stress echocardiography reveals that stroke volume, not heart rate, initially drives cardiac output increases. However, stroke volume changes alone do not reliably distinguish between ischemic and non-ischemic responses in patients with chest pain.
Area of Science:
- Cardiology
- Physiology
Background:
- Dobutamine stress echocardiography (DSE) is used to assess coronary artery disease.
- Understanding hemodynamic changes during DSE is crucial for accurate interpretation.
Purpose of the Study:
- To investigate the hemodynamic alterations, specifically changes in heart rate and stroke volume, during a standard DSE protocol.
- To determine the contribution of stroke volume and heart rate to cardiac output changes at different dobutamine infusion stages.
- To evaluate if stroke volume response can differentiate ischemic from non-ischemic conditions.
Main Methods:
- A standard DSE protocol with incremental dobutamine infusion (5-40 µg/kg/min) was administered to 69 patients.
- Hemodynamic parameters, including heart rate and stroke volume, were measured throughout the study.
- Stroke volume was calculated using Doppler echocardiography measurements.
Main Results:
- Heart rate significantly increased, with the most substantial rise occurring at higher dobutamine doses (>20 µg/kg/min).
- Mean stroke volume increased significantly from baseline, reaching its peak at higher doses (P < 0.0001).
- Most patients achieved maximal stroke volume by 20 µg/kg/min; however, blunted stroke volume rise in ischemic patients was not statistically significant (P = 0.09).
Conclusions:
- Early increases in cardiac output during DSE are primarily driven by stroke volume, followed by heart rate at higher doses.
- Individual stroke volume augmentation during DSE is insufficient to reliably differentiate between ischemic and non-ischemic responses.
Abstract:
We studied haemodynamic changes during dobutamine stress echocardiography in 69 patients (mean age 58 years, 6 female, 63 male) referred for investigation of chest pain. We used a standard protocol of 3 min stages using infusion rates of 5, 10, 20, 30 and 40 micrograms/kg/min. Heart rate rose from 74 (13) to 123 (21) beats per min with the major increment occurring during the high dose phase of the study (> 20 micrograms/kg/min). Stroke volume was calculated as the product of left ventricular outflow tract cross-sectional area and the velocity integral of the continuous wave aortic signal. Mean stroke volume increased from 67.5 (22) ml pre-test to 82 (22) ml at 20 micrograms/kg/min dose (P < 0.0001) and 85 (21) ml at 40 micrograms/kg/min (P < 0.00001). Only 15 patients (26%) reached their maximal stroke volume by 10 micrograms/kg/min, 38 patients (65%) reached maximal stroke volume by 20 micrograms/kg/min. Patients with ischaemic responses tended to have a blunted rise in stroke volume from 67 (22) ml to 85 (22) ml at maximum compared with a rise from 69 (23) to 92 (19) ml in those without ischaemic (P = 0.09). In conclusion, the early rise in cardiac output during dobutamine stress was mainly due to a rise in stroke volume and the later due to an increase in heart rate. Individual increases in stroke volume did not adequately differentiate between ischaemic and non-ischaemic results.