In een recente studie hebben Newton (what's in a name) en kollega's aangetoond dat
afbeelding: Wikipedia
(van PCr naar ATP en terug: recycling)
Twee slotopmerkingen zijn op zijn plaats:
- het betrof hier slechts een kleine studiegroep (12 CVS-patiënten) en
- "hartafwijkingen"/orthostatische intolerantie worden slechts bij een deel van de CVS-patiënten vastgesteld,
hetgeen wederom aangeeft hoe nietszeggend het label "CVS" is.
Citaten uit het studierapport:
Discussion
We have demonstrated that
the skeletal muscle bioenergetic abnormality recently described in patients with CFS [1]
associates with a similar cardiac bioenergetic abnormality.
This impairment is associated with an increase in cardiac contractility on standing
(i.e. the heart has to work harder for the same degree of physiological stress),
the severity of which associates with symptoms on standing in those with CFS.
The finding of varying degrees of muscle abnormality
may account for the contradictory results in the previous CFS muscle literature [25-29] and underlines
the need for a whole organ systematic approach to studies in CFS.
....
If our CFS patients are considered as a single group,
then oxidative muscle metabolism is not significantly impaired compared with controls,
as we had previously reported [1],
and this would not change by recruiting greater numbers:
division by cardiac status, however, suggests the presence of
subgroups within the population,
one of which has impaired oxidative muscle metabolism.
....
The relationship between cardiac contractility on standing and symptoms was an important finding
as it suggests that symptoms in those with CFS are potentially modifiable by treatment of the underlying cardiac abnormality.
These abnormalities were CFS-specific, as there were no such correlations in the control population.
....
When we considered cardiac energy metabolism in the whole CFS patient group,
this appeared to be mixed, with many individuals falling in the normal range
with some individuals showing impairment.
This suggests that within the symptom complex of CFS,
there is a group of patients in whom an actual cardiac abnormality is present
(defined by the presence of PCr /ATP ratio < 1.6 [17]).
....
The heterogeneity of patients included in CFS studies is well recognized,
however, despite the usage of specific diagnostic criteria for inclusion,
and we could not symptomatically differentiate between the normal and impaired cardiac energetic group.
This underlines how important it is to correctly characterize patients with CFS and
to study the underlying physiological parameter rather than the symptom complex.
....
It is unclear what the long-term impact of the cardiac abnormalities will have for those with CFS.
However, our findings of reduced
survival in those with the fatigue-associated chronic disease and primary biliary cirrhosis [31] and
studies confirming a comparable fatigue phenotype between primary biliary cirrhosis and CFS [32]
would point to an (as yet) unidentified risk for those with CFS, and
our findings of cardiac dysfunction in a proportion of patients may suggest the group at increased risk.
....
This study has examined the tolerability and diagnostic potential of assessment protocols
that examine haemodynamic responses to immediate and prolonged standing in CFS and,
for the first time, examines the relationship between measures of
cardiovascular function, cardiac energetics at rest and muscle energetics under exercise in CFS patients.
HUT is one of the assessment modalities of choice in the evaluation of those with unexplained syncope,
and is recommended in national and international guidelines [33-35].
In contrast, the UK NICE CFS guidelines [36] actively discourage the assessment by HUT.
This is surprising considering the apparent pathophysiological overlap between neurally mediated hypotension and CFS [37,38,39].
....
This study has some limitations.
The study group could clearly be considered to be self-selected, and as a result biased,
as they were recruited via the local patient support group.
However, all participants had been seen within a local CFS service within 2 years and been diagnosed with the formal Fukuda criteria.
A further limitation is that this study cannot establish a direction of causality for
the associations seen in cardiac metabolism, skeletal muscle metabolism and autonomic function.
....
The findings are, however,
consistent with a model in which a cardiovascular impairment might lead to impaired oxidative function,
perhaps through impaired venous run-off post-exercise.
Impaired cardiovascular response to standing in chronic fatigue syndrome.
Eur J Clin Invest. Published Online 23 May 2010. doi: 10.1111/j.1365-2362.2010.02310.x.
Hollingsworth KG, Jones DEJ, Taylor R, Blamire AM, Newton JL.
ABSTRACT
Background
Impaired skeletal muscle metabolism is recognized in chronic fatigue syndrome (CFS).
This study examined the relationship
between skeletal and cardiac muscle function and symptoms on standing in CFS
using magnetic resonance spectroscopy (MRS) and impedance cardiography.
Materials and methods
Phosphocreatine (PCr)/adenosine triphosphate (ATP) ratio by cardiac MRS,
PCr/ADP and proton efflux by muscle MRS
were performed in 12 CFS (Fukuda) and 8 controls.
Head up tilt (HUT) and cardiac contractility (left ventricular work index, LVWI)
(n = 64 CFS and matched controls) were found.
Fatigue impact was accessed by Fatigue Impact Scale and
orthostatic symptoms by Orthostatic Grading Scale (OGS).
Results
Cardiac PCr/ATP correlated with measures of muscle bioenergetic function
(half-time PCr recovery [κ = 0.71, P = 0.005] and half-time ADP recovery [κ = 0.60, P = 0.02])
suggesting that the muscle and cardiac bioenergetic function correlate in CFS.
Four of 12 (33.3%) CFS patients had PCr/ATP values
consistent with significant cardiac impairment.
Those with impaired cardiac energy metabolism
had significantly reduced maximal and initial proton efflux rates (P < 0.05).
Cardiac PCr/ATP ratio correlated with myocardial contractility (LVWI)
in response to standing (P = 0.03).
On HUT,
LVWI on standing was significantly higher in CFS (P = 0.05)
with symptoms on standing (OGS) occurring in 61/64 (95%)
(vs. 25/64 [39%] controls; P < 0.0001).
OGS scores were significantly higher
in those with abnormal LVWI responses to standing (P = 0.04),
with the LVWI on standing
correlating with OGS scores (r2 = 0.1; P = 0.03).
HUT was positive in 19 (32%).
Conclusions
Skeletal muscle and cardiac bioenergetic abnormalities associate in CFS.
Cardiac bioenergetic metabolism
associates with
increase in cardiac contractility on standing.
Haemodynamic assessment in CFS
is well tolerated and safe
with a high diagnostic yield
comparable with unexplained syncope.
KEYWORDS
Cardiac function, diagnosis, fatigue
http://www3.interscience.wiley.com/journal/123466596/abstract
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