Category Archives: Publications

Real-Time Analysis of the Heart Rate Variability During Incremental Exercise for the Detection of the Ventilatory Threshold.

Shiraishi Y; Katsumata Y; Sadahiro T; Azuma K; Akita K; Isobe S; Yashima F; Miyamoto K; Nishiyama T; Tamura Y; Kimura T; Nishiyama N; Aizawa Y; Fukuda K; Takatsuki S

Journal Of The American Heart Association [J Am Heart Assoc], ISSN: 2047-9980, 2018 Jan 07; Vol. 7

Background: It has never been possible to immediately evaluate heart rate variability (HRV) during exercise. We aimed to visualize the real-time changes in the power spectrum of HRV during exercise and to investigate its relationship to the ventilatory threshold (VT).
Methods and Results: Thirty healthy subjects (29.1±5.7 years of age) and 35 consecutive patients (59.0±13.2 years of age) with myocardial infarctions underwent cardiopulmonary exercise tests with an RAMP protocol ergometer. The HRV was continuously assessed with power spectral analyses using the maximum entropy method and projected on a screen without delay. During exercise, a significant decrease in the high frequency (HF) was followed by a drastic shift in the power spectrum of the HRV with a periodic augmentation in the low frequency/HF (L/H) and steady low HF. When the HRV threshold (HRVT) was defined as conversion from a predominant high frequency (HF) to a predominant low frequency/HF (L/H), the VO2 at the HRVT (HRVT-VO2) was substantially correlated with the VO2 at the lactate threshold and VT) in the healthy subjects (r=0.853 and 0.921, respectively). The mean difference between each threshold (0.65 mL/kg per minute for lactate threshold and HRVT, 0.53 mL/kg per minute for VT and HRVT) was nonsignificant (P>0.05). Furthermore, the HRVT-VO2 was also correlated with the VT-VO2 in these myocardial infarction patients (r=0.867), and the mean difference was -0.72 mL/kg per minute and was nonsignificant (P>0.05).
Conclusions: A HRV analysis with our method enabled real-time visualization of the changes in the power spectrum during exercise. This can provide additional information for detecting the VT.

Atrial Fibrillation in Heart Failure With Preserved Ejection Fraction: Association With Exercise Capacity, Left Ventricular Filling Pressures, Natriuretic Peptides, and Left Atrial Volume.

Lam CS, Rienstra M, Tay WT, Liu LC, Hummel YM, van der Meer P,
de Boer RA, Van Gelder IC, van Veldhuisen DJ, Voors AA, Hoendermis
ES.

JACC Heart Fail. 2017 Feb;5(2):92-98. doi: 10.1016/j.jchf.2016.10.005. Epub 2016
Dec 21.

OBJECTIVES: This study sought to study the association of atrial fibrillation
(AF) with exercise capacity, left ventricular filling pressure, natriuretic
peptides, and left atrial size in heart failure with preserved ejection fraction
(HFpEF).
BACKGROUND: The diagnosis of HFpEF in patients with AF remains a challenge
because both contribute to impaired exercise capacity, and increased natriuretic
peptides and left atrial volume.
METHODS: We studied 94 patients with symptomatic heart failure and left
ventricular ejection fractions ≥45% using treadmill cardiopulmonary exercise
testing and right- and/or left-sided cardiac catheterization with simultaneous
echocardiography.
RESULTS: During catheterization, 62 patients were in sinus rhythm, and 32
patients had AF. There were no significant differences in age, sex, body size,
comorbidities, or medications between groups; however, patients with AF had lower
peak oxygen consumption (VO2) compared with those with sinus rhythm (10.8 ± 3.1
ml/min/kg vs. 13.5 ± 3.8 ml/min/kg; p = 0.002). Median (25th to 75th percentile)
N-terminal pro-B-type natriuretic peptide (NT-proBNP) was higher in AF versus
sinus rhythm (1,689; 851 to 2,637 pg/ml vs. 490; 272 to 1,019 pg/ml; p < 0.0001).
Left atrial volume index (LAVI) was higher in AF than sinus rhythm (57.8 ± 17.0
ml/m2 vs. 42.5 ± 15.1 ml/m2; p = 0.001). Invasive hemodynamics showed higher mean
pulmonary capillary wedge pressure (PCWP) (19.9 ± 3.7 vs. 15.2 ± 6.8) in AF
versus sinus rhythm (all p < 0.001), with a trend toward higher left ventricular
end-diastolic pressure (17.7 ± 3.0 mm Hg vs. 15.7 ± 6.9 mm Hg; p = 0.06). After
adjusting for clinical covariates and mean PCWP, AF remained associated with
reduced peak VO2 increased log NT-proBNP, and enlarged LAVI (all p ≤0.005).
CONCLUSIONS: AF is independently associated with greater exertional intolerance,
natriuretic peptide elevation, and left atrial remodeling in HFpEF. These data
support the application of different thresholds of NT-proBNP and LAVI for the
diagnosis of HFpEF in the presence of AF versus the absence of AF.

Oxygen uptake on-kinetics during six-minute walk test predicts short-term outcomes after off-pump coronary artery bypass surgery.

Rocco IS, Viceconte M, Pauletti HO, Matos-Garcia BC,
Marcondi NO, Bublitz C, Bolzan DW, Moreira RSL, Reis MS,
Hossne NA Jr, Gomes WJ, Arena R, Guizilini S.

Disabil Rehabil. 2017 Dec 26:1-7. doi: 10.1080/09638288.2017.1401673. [Epub ahead
of print]

PURPOSE: We aimed to investigate the ability of oxygen uptake kinetics to predict
short-term outcomes after off-pump coronary artery bypass grafting.
METHODS: Fifty-two patients aged 60.9 ± 7.8 years waiting for off-pump coronary
artery bypass surgery were evaluated. The 6-min walk test distance was performed
pre-operatively, while simultaneously using a portable cardiopulmonary testing
device. The transition of oxygen uptake kinetics from rest to exercise was
recorded to calculate oxygen uptake kinetics fitting a monoexponential regression
model. Oxygen uptake at steady state, constant time, and mean response time
corrected by work rate were analysed. Short-term clinical outcomes were evaluated
during the early post-operative of off-pump coronary artery bypass surgery.
RESULTS: Multivariate analysis showed body mass index, surgery time, and mean
response time corrected by work rate as independent predictors for short-term
outcomes. The optimal mean response time corrected by work rate cut-off to
estimate short-term clinical outcomes was 1.51 × 10-3 min2/ml. Patients with
slower mean response time corrected by work rate demonstrated higher rates of
hypertension, diabetes, EuroSCOREII, left ventricular dysfunction, and impaired
6-min walk test parameters. The per cent-predicted distance threshold of 66% in
the pre-operative was associated with delayed oxygen uptake kinetics.
CONCLUSIONS: Pre-operative oxygen uptake kinetics during 6-min walk test predicts
short-term clinical outcomes after off-pump coronary artery bypass surgery. From
a clinically applicable perspective, a threshold of 66% of pre-operative
predicted 6-min walk test distance indicated slower kinetics, which leads to
longer intensive care unit and post-surgery hospital length of stay. Implications
for rehabilitation Coronary artery bypass grafting is a treatment aimed to
improve expectancy of life and prevent disability due to the disease progression;
The use of pre-operative submaximal functional capacity test enabled the
identification of patients with high risk of complications, where patients with
delayed oxygen uptake kinetics exhibited worse short-term outcomes; Our findings
suggest the importance of the rehabilitation in the pre-operative in order to
“pre-habilitate” the patients to the surgical procedure; Faster oxygen uptake
on-kinetics could be achieved by improving the oxidative capacity of muscles and
cardiovascular conditioning through rehabilitation, adding better results
following cardiac surgery.

Subclinical Hypothyroidism Is Associated With Adverse Prognosis in Heart Failure Patients.

Sato Y; Yoshihisa A; Department of Cardiovascular Medicine, Fukushima Medical University, Fukushima, Japan. Electronic address: yoshihis@fmu.ac.jp.
Kimishima Y; Kiko T; Watanabe S; Fukushima; Kanno Y;
et al.

The Canadian Journal Of Cardiology [Can J Cardiol] 2018 Jan; Vol. 34 (1), pp. 80-87. Date of Electronic Publication: 2017 Nov 08.

Background: It is widely recognized that overt hyper- as well as hypothyroidism are potential causes of heart failure (HF). Additionally it has been recently reported that subclinical hypothyroidism (sub-hypo) is associated with atherosclerosis, development of HF, and cardiovascular death. We aimed to clarify the effect of sub-hypo on prognosis of HF, and underlying hemodynamics and exercise capacity.
Methods: We measured the serum levels of thyroid stimulating hormone (TSH) and free thyroxine (FT4) in 1100 consecutive HF patients. We divided these patients into 5 groups on the basis of plasma levels of TSH and FT4, and focused on euthyroidism (0.4 ≤ TSH ≤ 4 μIU/mL and 0.7 ≤ FT4 ≤ 1.9 ng/dL; n = 911; 82.8%) and sub-hypo groups (TSH > 4 μIU/mL and 0.7 ≤ FT4 ≤ 1.9 ng/dL; n = 132; 12.0%). We compared parameters of echocardiography, cardiopulmonary exercise testing, and cardiac catheterization, and followed up for cardiac event rate and all-cause mortality between the 2 groups.
Results: Although left ventricular ejection fraction did not differ between the 2 groups, the sub-hypo group had lower peak breath-by-breath oxygen consumption and higher mean pulmonary arterial pressure than the euthyroidism group (peak breath-by-breath oxygen consumption, 14.0 vs 15.9 mL/min/kg; P = 0.012; mean pulmonary arterial pressure, 26.8 vs 23.5 mm Hg, P = 0.020). In Kaplan-Meier analysis (mean 1098 days), the cardiac event rate and all-cause mortality were significantly higher in the sub-hypo group than those in the euthyroidism group (log rank, P < 0.01, respectively). In Cox proportional hazard analysis, sub-hypo was a predictor of cardiac event rate and all-cause mortality in HF patients (P < 0.05, respectively).
Conclusions: Sub-hypo might be associated with adverse prognosis, accompanied by impaired exercise capacity and higher pulmonary arterial pressure, in HF patients.

Fit for surgery? Perspectives on preoperative exercise testing and training.

Richardson K; Levett DZH;  Jack S; Grocott MPW

British Journal Of Anaesthesia [Br J Anaesth] 2017 Dec 01; Vol. 119 (suppl_1), pp. i34-i43.

There is a consistent relationship between physical activity, physical fitness, and health across almost all clinical contexts, including the perioperative setting. Physiological measurements obtained during physical exercise may be used to infer the risk of adverse outcome after major surgery. In particular, data obtained from perioperative cardiopulmonary exercise testing have an expanding role in perioperative care. Such information may be used to inform a variety of changes in clinical practice, including interventions that may reduce the risk of perioperative adverse events. Specifically, for patients undergoing major cancer surgery there is a complex interplay between different cancer treatments, including neoadjuvant therapies (chemo- and chemo- plus radiotherapy), surgery, and physical fitness, and the modulation of these relationships by perioperative exercise interventions. Preoperative cardiopulmonary exercise testing provides an objective evaluation of physical fitness and has been used to provide an individualized risk profile in order to guide collaborative decision-making, inform the consent process, characterize and optimize co-morbidities, and to triage patients to perioperative care. Furthermore, studies evaluating exercise interventions aimed at increasing preoperative exercise capacity have established that training improves physical fitness. However, to date, this literature is largely composed of feasibility and pilot studies with small sample sizes, which are in general underpowered to assess clinical outcomes. Adequately powered prospective multicentre studies are needed to characterize the most effective means of improving patient fitness before surgery and to evaluate the impact of such improvements on surgical and disease-specific (e.g. cancer) outcomes.

The Maximal Oxygen Uptake Verification Phase: a Light at the End of the Tunnel?

Schaun GZ

Sports Med Open. 2017 Dec 8;3(1):44. doi: 10.1186/s40798-017-0112-1.

Commonly performed during an incremental test to exhaustion, maximal oxygen
uptake (V̇O2max) assessment has become a recurring practice in clinical and
experimental settings. To validate the test, several criteria were proposed. In
this context, the plateau in oxygen uptake (V̇O2) is inconsistent in its
frequency, reducing its usefulness as a robust method to determine “true”
V̇O2max. Moreover, secondary criteria previously suggested, such as expiratory
exchange ratios or percentages of maximal heart rate, are highly dependent on
protocol design and often are achieved at V̇O2 percentages well below V̇O2max.
Thus, an alternative method termed verification phase was proposed. Currently, it
is clear that the verification phase can be a practical and sensitive method to
confirm V̇O2max; however, procedures to conduct it are not standardized across
the literature and no previous research tried to summarize how it has been
employed. Therefore, in this review the knowledge on the verification phase was
updated, while suggestions on how it can be performed (e.g. intensity, duration,
recovery) were provided according to population and protocol design. Future
studies should focus to identify a verification protocol feasible for different
populations and to compare square-wave and multistage verification phases.
Additionally, studies assessing verification phases in different patient
populations are still warranted.

Repeatability and Meaningful Change of CPET Parameters in Normal Subjects.

DeCato TW, Bradley SM, Wilson EL, Hegewold MJ

Medicine And Science In Sports And Exercise [Med Sci Sports Exerc] 2017 Nov 07. Date of Electronic Publication: 2017 Nov 07.

Introduction/purpose: Cardiopulmonary exercise testing (CPET) plays an important role in clinical medicine and research. Repeatability of CPET parameters has not been well characterized, but is important to assess variability and determine if there have been meaningful changes in a given CPET parameter.
Methods: We recruited 45 healthy subjects and performed two symptom-limited CPETs within 30 days using a cycle ergometer. Differences in relevant CPET parameters between CPET-1 and CPET-2 were assessed using a paired t-test. Coefficient of variation (CoV) and Bland-Altman plots are reported. Factors that may be associated with variability were analyzed (sex, age, time of day, fitness level). The coefficient of repeatability was calculated for peak V˙O2 and V˙O2 at lactate threshold (LT) to establish a 95% threshold for meaningful change.
Results: There were no significant differences between tests in the parameters reported. Specifically, we found overall low CoV in peak V˙O2 (4.9%), V˙O2@LT (10.4%), peak O2 pulse (4.6%), peak V˙E (7.4%), V˙E/V˙CO2@LT (4.0%) andV˙E/V˙O2@LT (4.8%). The CoV for RER@LT was significantly affected by diurnal factors; age, sex and fitness level did not impact variability. The 95% threshold for meaningful change in peak V˙O2 was 0.540 L/min and for V˙O2@LT was 0.520 L/min.
Conclusions: Repeatability of CPET parameters is generally higher then previously reported. There were no significant differences in variability related to sex, age, fitness level; diurnal factors had a limited impact. The threshold for meaningful change in peak V˙O2 and for V˙O2@LT should be considered when gauging a response to therapies or training.

Pregnancy After Transcatheter Pulmonary Valve Implantation.

Kozicka U; Weroński K; Rużyłło W; Demkow M; Kowalski M; Śpiewak M;
Piotrowicz E; Siudalska H; Hoffman P; Biernacka EK

The Canadian Journal Of Cardiology [Can J Cardiol], ISSN: 1916-7075, 2017 Dec; Vol.
33 (12), pp. 1737.e5-1737

Transcatheter pulmonary valve implantation (TPVI) is a relatively new
method of treating patients with significant pulmonary regurgitation or
pulmonary stenosis, or both, after reconstruction of the right
ventricular outflow tract. It is an attractive alternative to conduit
replacement in this group of patients, who are typically young and
active. This report includes 4 young women who after successful TPVI
became pregnant and gave birth. Transthoracic echocardiography,
cardiopulmonary exercise testing, and cardiac magnetic resonance
imaging were performed in all patients. The results suggest that
pregnancy and delivery after successful TPVI is safe when the
appropriate precautions have been taken.Copyright © 2017 Canadian
Cardiovascular Society.

Repeatability and Meaningful Change of CPET Parameters in Normal Subjects

DeCato TW, Bradley SM, Wilson EL, Hegewald MJ.

Med Sci Sports Exerc. 2017 Nov 7. doi: 10.1249. [Epub ahead
of print]

INTRODUCTION/PURPOSE: Cardiopulmonary exercise testing (CPET) plays an important
role in clinical medicine and research. Repeatability of CPET parameters has not
been well characterized, but is important to assess variability and determine if
there have been meaningful changes in a given CPET parameter.
METHODS: We recruited 45 healthy subjects and performed two symptom-limited CPETs
within 30 days using a cycle ergometer. Differences in relevant CPET parameters
between CPET-1 and CPET-2 were assessed using a paired t-test. Coefficient of
variation (CoV) and Bland-Altman plots are reported. Factors that may be
associated with variability were analyzed (sex, age, time of day, fitness level).
The coefficient of repeatability was calculated for peak V˙O2 and V˙O2 at lactate
threshold (LT) to establish a 95% threshold for meaningful change.
RESULTS: There were no significant differences between tests in the parameters
reported. Specifically, we found overall low CoV in peak V˙O2 (4.9%), V˙O2@LT
(10.4%), peak O2 pulse (4.6%), peak V˙E (7.4%), V˙E/V˙CO2@LT (4.0%)
andV˙E/V˙O2@LT (4.8%). The CoV for RER@LT was significantly affected by diurnal
factors; age, sex and fitness level did not impact variability. The 95% threshold
for meaningful change in peak V˙O2 was 0.540 L/min and for V˙O2@LT was 0.520
L/min.
CONCLUSIONS: Repeatability of CPET parameters is generally higher then previously
reported. There were no significant differences in variability related to sex,
age, fitness level; diurnal factors had a limited impact. The threshold for
meaningful change in peak V˙O2 and for V˙O2@LT should be considered when gauging
a response to therapies or training.

Recovery of the cardiac autonomic nervous and vascular system after maximal cardiopulmonary exercise testing in recreational athletes.

Weberruss H; Maucher J; Oberhoffer R; Müller J,

European Journal Of Applied Physiology [Eur J Appl Physiol], ISSN: 1439-6327, 2017 Nov 15;

Objective: The body’s adaptation to physical exercise is modulated by sympathetic and parasympathetic (vagal) branches of the autonomic nervous system (ANS). Heart rate variability (HRV), the beat-to-beat variation of the heart, is a proxy measure for ANS activity, whereas blood pressure (BP) is an indicator for cardiovascular function. Impaired vagal activity and lower BP is already described after exercise. However, inconsistent results exist about how long vagal recovery takes and how long post-exercise hypotension persists. Therefore, the aim of this study was to assess HRV and BP 1 h after maximal cardiopulmonary exercise testing (CPET).
Patients and Methods: HRV (Polar RS800CX), peripheral and central BP (Mobil-O-Graph®) were prospectively studied in 107 healthy volunteers (47 female, median age 29.0 years) in supine position, before and 60 min after maximal CPET.
Results: One hour after terminating CPET measures of HRV were still impaired and post-exercise BP was significantly reduced suggesting an improved vascular function compared to pre levels. HRV parameters post-exercise were 34.7% (RMSSD), 67.2% (pNN50), 57.2% (HF), and 42.7% (LF) lower compared to pre-exercise levels (for all p < 0.001). Median reduction in BP was 5 mmHg for systolic BP (p < 0.001), and 4 mmHg for diastolic BP (p = 0.016) and central systolic post-exercise (p = 0.005).
Conclusions: One hour after terminating strenuous exercise, autonomic nervous regulation seems to be postponed which is reflected in reduced HRV, whereas the early recovery of the vasculature, post-exercise hypotension, is still preserved over the recovery period of 1 h.