Heart Rate Responses During Exercise by Dominant Ventricle in Pediatric and Young Adult Patients With a Fontan Circulation

BackgroundPatients with univentricular physiology palliated with the Fontan operation have multiple late cardiovascular and extracardiac complications, including autonomic dysfunction. Despite the observation, little is known about autonomic function driving exercise-related heart rate responses in Fontan patients and whether dominant ventricle subtype or underlying cardiac anatomy affects heart rate responses during exercise.MethodsWe performed a retrospective chart review of all single ventricle patients palliated with a Fontan operation who underwent a maximal effort cardiopulmonary exercise test at Cincinnati Children’s Hospital Medical Center from 2013 to 2018.ResultsOne hundred and three Fontan patients aged 16.7 ± 5.5 years were included in this study. Although both the systemic right (n = 38) and systemic left (n = 65) ventricle groups demonstrated chronotropic incompetence, there were no differences between the groups in maximal heart rate (167.5 ± 17.4 vs 169.6 ± 20.9 bpm, P = 0.59), heart rate reserve (87.3 ± 22.6 vs 96.8 ± 25.7, P = 0.06) nor chronotropic index (70 ± 13% vs 74 ± 20%, P = 0.19). In addition, there were no differences between the groups in heart rate recovery at 1, 3, 5, and 10 minutes. Interestingly, patients with hypoplastic left heart syndrome (n = 34) had lower heart rate reserve (84.76 ± 22.8 vs 96.38 ± 26.75, P = 0.04) and chronotropic index (70.5 ± 12.5% vs 76.3 ± 13.2%, P = 0.04) compared with patients with tricuspid atresia (n = 42).ConclusionsFontan patients commonly have chronotropic incompetence, diminished heart rate reserve but with preserved heart rate recovery. Although there is overall no difference in chronotropy in Fontan patients based on dominant systemic ventricle, there is a difference between patients with hypoplastic left heart syndrome and those with tricuspid atresia.     

Clinical Outcomes in Adolescents and Adults After the Fontan Procedure

Background

Long-term outcomes of Fontan patients who survive to age ≥16 years have not been well characterized. The Australian and New Zealand Fontan Registry (ANZFR) provides a unique opportunity to understand survival and complication rates in Fontan patients who transition to adult congenital heart disease centers.

Acute Responses to Intermittent and Continuous Exercise in Heart Failure Patients

Background

The purpose of this study was to compare cardiopulmonary responses, exercise adherence, tolerance, and safety of optimized high-intensity interval exercise (HIIE) compared with moderate-intensity continuous exercise (MICE) in patients with heart failure and reduced ejection fraction (HFREF).

Methods

Twenty patients with HFREF (aged 61 ± 9.9 years) were randomly assigned to HIIE corresponding to 2 × 8 minutes of 30-second intervals at 100% of peak power output and 30-second passive recovery intervals and to a 22-minute MICE corresponding to 60% of peak power output. Gas exchange, electrocardiogram, and blood pressure were measured continuously. Cardiac troponin T (cTnT), C-reactive protein (CRP), and brain natriuretic peptide (BNP) were measured before, 20 minutes after, and 24 hours after HIIE and MICE.

Results

Cardiopulmonary responses did not differ between MICE and HIIE. Higher exercise adherence and efficiency were observed on HIIE with a similar perceived exertion and time spent above 90% of peak oxygen consumption compared with MICE. Neither HIIE nor MICE caused any significant arrhythmias or increased CRP, BNP, or cTnT.

Conclusions

Compared with MICE, HIIE demonstrated a higher exercise adherence and was well tolerated in patients with HFREF, while still providing a high-level physiological stimulus and leaving indices of inflammation (CRP), myocardial dysfunction (BNP), and myocardial necrosis (cTnT) unaffected.     

Hormonal Responses to Exercise Stress Test in Patients with Fibromyalgia Syndrome

Twenty patients with fibromyalgia syndrome (FMS) and 20 matched healthy controls were subjected to an exercise stress test above their anaerobic threshold. Serum samples for the measurement of growth hormone (GH), insulin-like growth factor-1 (IGF-1), prolactin (PRL), adrenocorticotrophic hormone (ACTH) and cortisol were taken prior to and after the test at 30-min intervals. Compared to the controls, the patients with FMS displayed significantly lower basal GH levels and slightly, though significantly, higher prolactin levels. Following the exercise test there was a significant increase in the mean GH level in the patient group (P = 0.0474) and a significant decrease in the control group (P = 0.0286) 1 hour after the exercise. A slight decrease in ACTH levels in the control group was observed (P= 0.0002), but there was no significant change in FMS patients. Cortisol levels were significantly lower in both groups after the exercise (P= 0.0001). These results suggest the possibility of a perturbation in hormonal response to exercise in patients with FMS. Received: 25 August 2000 / Accepted: 30 May 2001     

The Unique Clinical Phenotype and Exercise Adaptation of Fontan Patients With Normal Exercise Capacity

BackgroundExercise limitation is almost universal among Fontan patients. Identifying unique clinical features in the small fraction of Fontan patients with normal exercise capacity (high-capacity Fontan [HCF]) provides potential to inform clinical strategies for those with low exercise capacity (usual Fontan).MethodsWe performed a retrospective chart review of all patients with single-ventricle physiology palliated with a Fontan operation who underwent incremental cardiopulmonary exercise testing at Cincinnati Children’s Hospital Medical Center from 2013 to 2018. Comparison was between patients with peak oxygen uptake < vs ≥ 80% predicted.ResultsA total of 22 of 112 patients were classified as HCF (68% were female; aged 18 ± 7 years). During incremental exercise, peak oxygen uptake (86.1% ± 6.1% vs 62% ± 12.2% predicted; P < 0.001) was greater in HCF vs usual Fontan despite similar chronotropic impairment, resulting in a greater oxygen pulse in HCF. Pulmonary function, breathing reserve, and ventilatory equivalent for CO₂ output slope were not different between groups. Those in the HCF group were more likely to self-report exercise ≥ 4 days/week for at least 30 minutes (77% vs 10%, P < 0.001), have normal systolic function (95% vs 74%, P = 0.003), have fewer postoperative complications (8% vs 36%, P = 0.04), and have shorter post-Fontan length of stay (8 ± 2.8 vs 12.4 ± 0.9 days, P = 0.04).ConclusionsApproximately 1 in 5 Fontan patients who undergo cardiopulmonary exercise testing have normal exercise capacity despite chronotropic impairment. This implies a better preserved stroke volume, perhaps due to greater muscle pump-mediated preload. Additionally, a complicated perioperative Fontan course is associated with eventual impaired functional capacity.     

Noninvasive Assessment of Liver Fibrosis in Adult Patients Following the Fontan Procedure

Objective. Recent data indicate that patients after the Fontan procedure are at risk for significant liver dysfunction; however, the prevalence and extent of liver disease in the Fontan population remains unknown. Furthermore, limited data exist in regard to screening for liver disease in adult Fontan patients. We sought to determine the prevalence of liver disease in adult patients following the Fontan procedure using computed tomography (CT) and serum biomarkers of liver fibrosis. Design. Adult Fontan patients underwent screening for liver disease as part of their annual evaluation. Screening consisted of laboratory evaluation and dual‐phase liver CT scan. Laboratory evaluation included analysis of liver function, viral hepatitis serologies, and FibroSURE panel (LabCorp), a test that analyzes the results of serum biomarkers to provide a quantitative surrogate marker for liver fibrosis. Results. Sixteen patients, mean age 30.3 (range 20–41) years, were enrolled in the study. Mean length of follow‐up from time of Fontan palliation was 20.5 (range 11–33) years. No patients had serologic evidence of viral hepatitis or synthetic liver dysfunction. Twelve patients (75%) had abnormal FibroSURE scores, seven (44%) had elevated FibroSURE scores predictive of Metavir fibrosis stage F2 or greater on liver biopsy, and one (6%) had a FibroSURE score predictive of cirrhosis on biopsy. All 16 patients had abnormal radiologic liver findings identified on CT, including heterogeneous enhancement in 11 (69%), varices in six (38%), and liver nodules in five patients (31%). Length of time since Fontan surgery correlated significantly with an elevated FibroSURE score (P = .05) and having more CT scan abnormalities (P = .04). Conclusions. Liver fibrosis detected by serum biomarkers and dual phase CT scan is common in adult patients following the Fontan procedure. Further studies are needed to determine the long‐term clinical significance of these findings.     

Abnormal Response to Exercise in Middle-aged NIDDM Patients with and without Autonomic Neuropathy

The cardiovascular response to exercise in middle-aged non-insulin-dependent diabetes mellitus (NIDDM) patients and the potential role of clinical characteristics and autonomic function were evaluated. One hundred and eight NIDDM patients, aged 40–65 years, were compared with a control group of 112 subjects, matched by age, sex, physical fitness, and presence of hypertension. All subjects performed a maximal exercise test. The diabetic patients completed cardiovascular autonomic neuropathy (CAN) tests: deep breathing, postural hypotension and lying to standing. There were no significant differences in total work capacity, heart rate, and blood pressure, either at rest or at peak exercise between the two groups. Diabetic patients showed significantly lower values of systolic and diastolic blood pressure during exercise, significantly slower recovery of heart rate (at 5th minute the average values were 102.7 ± 14.1 beats min⁻¹ vs 91.9 ± 11.1, p < 0.001); and significantly higher proportion of blunted increase of heart rate (9.2 % vs 0.9 %, p < 0.001) and systolic blood pressure (9.2 % vs 0.7 %, p < 0.001) during exercise. No correlation between the exercise results and the main clinical characteristic (presence of hypertension, BMI, duration of diabetes, treatment, microalbuminuria, total score of CAN) was observed. These findings suggest that the cardiovascular response to exercise could be impaired also in the absence of signs of CAN. This impairment was higher in patients showing a dysfunction of orthosympathetic activity.     

Blood Pressure Responses to Exercise as Predictors of Blood Pressure Level After 5 Years

There is considerable disagreement in the literature on the clinical usefulness of exercise testing as a tool for prediction of future hypertension. Much of the discrepancy between various reports is attributable to the difficulties of blood pressure (BP) measurement during exercise. Therefore, we investigated whether accurate intraarterial. BP measurement will increase the predictive power of exercise testing. The BP responses to dynamic and isometric exercise were evaluated in 97 healthy, unmedicated men, of whom 34 were normotensive (NT), 29 borderline (BHT), and 34 mildly hypertensive (HT) using three criteria: 1) achieved BP during the test, 2) the change of the BP from baseline to exercise, and 3) the group was divided into high responders (HIGH, n = 19, systolic BP ≥220 and diastolic BP ≥105 mm Hg) and normal responders (n = 60). Five years later the BP was reassessed by casual measurements and noninvasive ambulatory 24-h monitoring (NAMB) in 79 (81%; 27 NT, 24 BHT, and 28 HT) subjects.The achieved isometric BP correlated well with the follow-up BP (casual systolic BP r = 0.43, diastolic BP r = 0.45, and NAMB systolic BP r = 0.44, diastolic BP r = 0.58, P < .001). However, achieved dynamic BP showed a poorer relationship to future BP (r range, 0.09 to 31, P = NS to P < .01). Because the intraarterial preexercise sitting BP also correlated well with follow-up BP (r range, 0.33 to 0.48, P < .01 to P < .001), and the r values were close to those of achieved isometric BP we used multiple regressions (including all resting and exercise BP values as independent variables) to evaluate the contributions of the baseline and exercise values for prediction of the follow-up BP. The baseline value explained 12% to 23% (from casual diastolic BP to NAMB diastolic BP, systolic BP values) of future BP variance, whereas achieved isometric BP ranged an additional 1% to 11% (from casual systolic BP to NAMB diastolic BP) of variance. In general, BP change from baseline with stressors did not correlate with follow-up measurements. In the high responder group the achieved dynamic BP did not correlate significantly with the follow-up BP, whereas the achieved isometric diastolic BP did correlate (casual diastolic BP r = 0.56, P < .05, NAMB systolic BP and diastolic BP r = 0.52, P < .05). Both groups had similar future BP levels.In conclusion, even with very accurate BP readings the reactivity to dynamic exercise is a weak predictor of future BP, and does not improve the prediction compared to resting BP values. Intraarterial BP response to isometric exercise marginally improves the prediction of future BP levels.