Key result
In an ex vivo porcine model of severe aortic regurgitation, increasing heart rate from 40 to 120 bpm significantly reduced the regurgitation fraction from 88% to 42% (p<0.001).
Why the study?
Although increasing heart rate is recommended to reduce regurgitation fraction in high-grade aortic regurgitation, chronic heart rate reduction in HFREF improves aortic compliance and could potentially decrease regurgitation fraction.
Does varying heart rate, stroke volume, and aortic compliance affect regurgitation fraction in an ex vivo model of severe aortic regurgitation?
Does varying heart rate, stroke volume, and aortic compliance affect regurgitation fraction in an ex vivo model of severe aortic regurgitation?
Absolute Event Rate: 42% vs 88%
p-value: p=<0.001
Increasing heart rate and stroke volume reduces regurgitation fraction in severe aortic regurgitation independent of aortic compliance, supporting recommendations to avoid heart rate-lowering drugs in these patients.
Introduction Drug therapy to reduce the regurgitation fraction (RF) of high-grade aortic regurgitation (AR) by increasing heart rate (HR) is generally recommended. However, chronic HR reduction in HFREF patients can significantly improve aortic compliance and thereby potentially decrease RF. To clarify these contrasts, we examined the influence of HR, aortic compliance and stroke volume (SV) on RF in an ex vivo porcine model of severe AR. Methods Experiments were performed on porcine ascending aorta with aortic valves (n=12). Compliance was varied by inserting a Dacron graft close to the aortic valve. Both tube systems were connected to a left heart simulator varying HR and SV. AR was accomplished by punching a 0.3 cm 2 hole in one aortic cusp. Flow, RF, SV and aortic pressure were measured, aortic compliance with transoesophageal ultrasound probes. Results Compliance of the aorta was significantly reduced after Dacron graft insertion (0.55%±0.21%/mm Hg vs 0.01%±0.007%/mm Hg, p<0.001, respectively). With increasing HR, RF was significantly reduced in each steady state of the native aorta (HR 40 bpm: 88%±7% vs HR 120 bpm: 42%±10%; p<0.001), but Dacron tube did not affect RF (HR 40 bpm: 87%±8%; p=0.79; HR 120 bpm: 42%±3%; p=0.86). Increasing SV also reduced RF independent of the stiff Dacron graft. Conclusion Aortic compliance did not affect AR in the ex vivo porcine model of AR. RF was significantly reduced with increasing HR and SV. These results affirm that HR lowering and negative inotropic drugs should be avoided to treat severe AR.
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Reil et al. (2023) studied Severe aortic regurgitation (n=12). Increasing heart rate vs. Lower heart rate (40 bpm) was evaluated on Regurgitation fraction (RF) (p=<0.001). In an ex vivo porcine model of severe aortic regurgitation, increasing heart rate from 40 to 120 bpm significantly reduced the regurgitation fraction from 88% to 42% (p<0.001).
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