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Identification of a Structural Abnormality
Algorithm for the Diagnosis
of Heart Failure 2
A complete history and physical examination
are the first steps in evaluating the structural abnormality
or cause responsible for the development of HF. Although
the history and physical examination may provide important
clues about the nature of the underlying cardiac abnormality,
identification of the structural abnormality leading
to HF generally requires either noninvasive or invasive
imaging of the cardiac structures.1,2
The single most useful diagnostic
test in the evaluation of patients with HF is the two-dimensional
echocardiogram, coupled with Doppler flow studies. This
test allows the physician to determine whether the primary
abnormality is pericardial, myocardial or valvular and
if myocardial, whether the dysfunction is primary systolic
or diastolic. The measurement of left ventricular ejection
fraction is the primary functional information gained
from the echocardiogram. The hallmark of patients with
predominant systolic dysfunction is a depressed left
ventricular ejection fraction (generally less than 40%).1
It must be recognized, however, that the reproducibility
of ejection fraction is poor, even when the same technicians
are used.2 Further, echocardiography slots
are limited and typically not available in many institutions
24 hours / 7 days a week.
Because it is not uncommon for a patient to have more
than one cardiac abnormality that contributes to the
development of HF, the echocardiogram provides additional
value by allowing for the quantitative assessment of
the dimensions, geometry, thickness, and regional motion
of the right and left ventricles and the qualitative
evaluation of the atria, pericardium, valves and vascular
structures.1,2
Other tests may be used to provide
information regarding the nature and severity of the
cardiac abnormality:1,2
- Radionuclide Ventriculography
provides highly accurate measurements of global and
regional functions, but it is unable to directly assess
cardiac hypertrophy or valvular abnormalities.
- Magnetic Resonance Imaging or
Computed Tomography may help evaluate ventricular
mass, detect right ventricular dysplasia or recognize
the presence of pericardial disease. They are accurate
and reproducible methods for the measurement of cardiac
volumes, wall thicknesses and left ventricular mass.
They also reliably detect thickened pericardium and
quantitate myocardial necrosis, perfusion and function.2
- Chest Radiography should be part
of the initial diagnostic work-up in heart failure,
because it is useful in detecting the presence of
pulmonary disease or estimate the degree of cardiac
enlargement or pulmonary congestion. Because of a
low sensitivity and specificity, this test should
not form the primary basis for determining the specific
cardiac abnormality responsible for the development
of HF.
- 12-lead Electrocardiogram is
helpful in demonstrating evidence of a prior MI, left
ventricular hypertrophy or a cardiac arrhythmia. Because
of a low sensitivity and specificity, this test should
not form the primary basis for determining the specific
cardiac abnormality responsible for the development
of HF.
Electrocardiographic changes in patients with HF are
frequent. The negative predictive value of a normal
ECG exceeds 90%. Conversely, the presence of anterior
Q waves and a left bundle branch block in patients
with ischemic heart disease are good predictors of
a decreased ejection fraction.2
For more information, click on the
following subjects:
Clinical
Assessment of Patients with Heart Failure
Identification of a Structural Abnormality
Evaluating
the Cause of Ventricular Dysfunction
The Role of
Natriuretic Peptides
References
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