Biomedical Engineering Reference
In-Depth Information
Role of Circulating Biomarkers and Mediators
of Cardiovascular Dysfunction
Both circulating biomarkers and mediators of cardiovascular dysfunction play a role
in acute illness. Some of these circulating biomarkers reflect mediator action on the
peripheral vasculature, such as endothelium-derived endothelin and nitrite/nitrate,
the stable end products of NO. Other biomarkers mainly reflect actions on the heart,
such as the natriuretic peptide family, released from the heart upon dilatation, serving
as a marker of congestive heart failure. Some factors may be both markers as well as
mediators of cardiovascular dysfunction of the acutely ill and bear prognostic signifi-
cance. Assessing circulating levels may help refine clinical judgment of the cardio-
vascular derangements encountered at the bedside, together with clinical signs and
hemodynamic variables (Beishuizen et al.
2005
). For instance, assessing natriuretic
peptides in patients with pulmonary edema of unclear origin may help to diagnose
congestive heart failure and cardiogenic pulmonary edema, when the pulmonary
capillary wedge pressure is not measured or inconclusive. Future aligning of hemo-
dynamic abnormalities with patterns of circulating cardiovascular markers/mediators
may help to stratify patients for inclusion in studies to assess the causes, response to
therapy, and prognosis of cardiovascular derangements in the acutely ill patients.
Use of Protein Biomarkers for Monitoring Acute
Coronary Syndromes
Although it is easy to diagnose myocardial infarction, no accurate noninvasive
efficient method of detecting acute coronary disease in an emergency or outpatient
setting in patients with minimal or nonspecific symptoms is available as yet. Many
of these patients are discharged without further investigations. They are considered
to be low risk as only 2-5% of patients who develop myocardial infarction later on,
initially present in this manner and are discharged home. However, more than 5%
of patients who present with atypical chest pain initially are ultimately diagnosed
as acute coronary syndrome. A blood biomarker test would be useful to sort out
these patients. Although a number of protein biomarkers of inflammation have been
discovered, their use in outpatient setting has not been investigated adequately.
Only C-reactive protein has been studied sufficiently for analysis of data. However,
the threshold for a positive C-reactive protein remains unknown. Published evi-
dence is not yet sufficient to support the routine use of new protein markers in
screening for ACS in the emergency department setting.
In spite of the limitation, the most frequently used biomarker in the emergency
department (ED) continues to be cardiac troponin (Tn). Other markers that have
been used because of the need in the ED for rapid triage have been myoglobin and
FABP. In addition, some centers still prefer less sensitive and less specific markers
such as CK-MB. More recently, a push has occurred to develop markers of isch-
emia, such as ischemia modified albumin (IMA), to determine which patients have
ischemia, even in the absence of cardiac injury.
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