Dynamic handgrip exercise elicited similar middle cerebral artery blood velocity kinetic responses in patients with Fontan circulation and healthy controls (time constant 20 vs 24 s, P=0.466).
Observational (n=16)
Does dynamic handgrip exercise elicit impaired middle cerebral artery blood velocity kinetic responses in patients with Fontan circulation compared to healthy controls?
The kinetic cerebrovascular responses to small muscle mass dynamic exercise remain intact in patients with Fontan circulation, despite lower handgrip strength.
Absolute Event Rate: 20% vs 24%
p-value: p=0.466
Patients with Fontan circulation (FTN) display cerebrovascular dysfunction. In addition, FTN is associated with impaired peripheral vascular responses to exercise, which contributes to their exercise intolerance. Given these characteristics, we tested the hypothesis that the middle cerebral artery blood velocity (MCAVmean) kinetic response to small muscle mass exercise using dynamic handgrip will be impaired in patients with FTN. Patients with FTN (2F/4M, 18 ± 3 years of age) and similarly-aged healthy controls (3F/7M, 16 ± 3 years of age, P=0.247) were instrumented to measure contralateral MCAVmean during handgrip exercise. Participants completed three maximal voluntary contractions (MVC). Following the determination of MVC, participants completed three bouts of five minutes of dynamic handgrip exercise at 40% MVC with a 1:1 duty cycle, with a three-minute recovery between bouts. The MCAVmean responses to dynamic handgrip were averaged for each participant. A mono-exponential model with time delay was used to evaluate the averaged MCAVmean responses to dynamic handgrip. Analyses were made using unpaired t-test, with significance set at P< 0.05. Patients with FTN had lower handgrip strength than controls (9 ± 4 kg vs 17 ± 7 kg, P=0.018). The MCAVmean in patients with FTN and controls had similar resting (59 ± 16 cm/s vs 71 ± 11 cm/s, P=0.104) and increases in amplitudes (4 ± 2 cm/s vs 2 ± 1 cm/s, P=0.307) during dynamic handgrip exercise. Further, during dynamic handgrip exercise, patients with FTN and controls exhibited similar time delays (33 ± 16 s vs 47 ± 25 s, P=0.247) and time constants (t, 20 ± 3 s vs 24 ± 12 s, P=0.466). These findings suggest that the kinetic cerebrovascular responses to small muscle mass dynamic exercise remain intact in patients with FTN. Funding: Saskatchewan Centre for Patient-Oriented Research, Saskatchewan Health Research Foundation, Heart and Stroke Foundation of Canada, Scottish Rite Charitable Foundation of Cananda, Canadian Institute of Health Research This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.
Jurrissen et al. (Fri,) conducted a observational in Fontan circulation (n=16). Dynamic handgrip exercise vs. Healthy controls was evaluated on Middle cerebral artery blood velocity (MCAVmean) time constant (t) (p=0.466). Dynamic handgrip exercise elicited similar middle cerebral artery blood velocity kinetic responses in patients with Fontan circulation and healthy controls (time constant 20 vs 24 s, P=0.466).