Application of non-invasive bioreactance to assess hemodynamic function in patients with hypertrophic cardiomyopathy
Nduka Charles Okwose1,2, Amy S Fuller1,3, Alaa I Alyahya1,3
1Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.
Insights
Patients with hypertrophic cardiomyopathy (HCM) show reduced exercise capacity due to impaired cardiac function, not peripheral issues. Non-invasive bioreactance technology helps evaluate this hemodynamic response during exercise stress tests.
Area of Science:
- Cardiology
- Exercise Physiology
Background:
- Non-invasive methods are increasingly used for cardiac function assessment.
- Hypertrophic cardiomyopathy (HCM) can lead to exercise intolerance.
Purpose of the Study:
- To evaluate the hemodynamic response to cardiopulmonary exercise stress testing in HCM patients using bioreactance technology.
- To compare exercise capacity and hemodynamic parameters between HCM patients and healthy controls.
Main Methods:
- Maximal graded cardiopulmonary exercise stress testing was performed on 29 HCM patients and 12 healthy controls.
- Simultaneous non-invasive hemodynamic monitoring using bioreactance and gas exchange measurements were employed.
- Key hemodynamic variables (cardiac output, stroke volume, cardiac power output) and metabolic data (oxygen consumption) were analyzed at rest and peak exercise.
Main Results:
- At rest, HCM patients had significantly lower cardiac output, stroke volume, and cardiac power output compared to controls.
- During peak exercise, HCM patients exhibited lower heart rate, cardiac output, cardiac power output, mean arterial blood pressure, and oxygen consumption.
- Peak arteriovenous oxygen difference and stroke volume were not significantly different between groups, suggesting central rather than peripheral limitations.
Conclusions:
- Functional capacity is significantly reduced in patients with HCM, primarily due to diminished central (cardiac) factors.
- Non-invasive hemodynamic assessment using bioreactance can enhance understanding of exercise intolerance mechanisms in HCM.
- This technology may offer valuable insights into the pathophysiology of HCM and exercise limitations.
Abstract:
Non-invasive technologies have become popular for the clinical evaluation of cardiac function. The present study evaluated hemodynamic response to cardiopulmonary exercise stress testing using bioreactance technology in patients with hypertrophic cardiomyopathy. The study included 29 patients with HCM (age 55 ± 15 years; 28% female) and 12 age (55 ± 14 years), and gender matched (25% female) healthy controls. All participants underwent maximal graded cardiopulmonary exercise stress testing with simultaneous non-invasive hemodynamic bioreactance and gas exchange. At rest, patients with HCM demonstrated significantly lower cardiac output (4.1 ± 1.3 vs. 6.1 ± 1.2 L/min; p < 0.001), stroke volume (61.5 ± 20.8 vs. 89.5 ± 19.8 mL/beat; p < 0.001), and cardiac power output (0.97 ± 0.3 vs. 1.4 ± 0.3watt; p < 0.001), compared to controls. At peak exercise, the following hemodynamic and metabolic variables were lower in HCM patients that is, heart rate (118 ± 29 vs. 156 ± 20 beats/min; p < 0.001), cardiac output (15.5 ± 5.8 vs. 20.5 ± 4.7 L/min; p = 0.017), cardiac power output (4.3 ± 1.6 vs. 5.9 ± 1.8 watts; p = 0.017), mean arterial blood pressure (126 ± 11 vs. 134 ± 10 mmHg; p = 0.039), and oxygen consumption (18.3 ± 6.0 vs. 30.5 ± 8.3 mL/kg/min; p < 0.001), respectively. Peak arteriovenous oxygen difference and stroke volume were not significantly different between HCM patients and healthy controls (11.2 ± 6.4 vs. 11.9 ± 3.1 mL/100 mL, p = 0.37 and 131 ± 50.6 vs. 132 ± 41.9 mL/beat, p = 0.76). There was a moderate positive relationship between peak oxygen consumption and peak heart rate (r = 0.67, p < 0.001), and arteriovenous oxygen difference (r = 0.59, p = 0.001). Functional capacity is significantly reduced in patients with HCM primarily due to diminished central (cardiac) rather than peripheral factors. Application of non-invasive hemodynamic assessment may improve understanding of the pathophysiology and explain mechanisms of exercise intolerance in hypertrophic cardiomyopathy.
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