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Department
of Podiatry - Vascular Assessment
Heart
disease
Heart
disease is a broad term that covers an array of medical conditions associated
with cardiac failure. Cotran, Kumar and Collins (1999) identify 5 types
of heart disease, of which the two most common will be discussed here:
1) Ischaemic Heart Disease (IHD)
IHD is, at a prevalence of 80 to 90%, by far the most common cause of
death due to heart disease (Cotran et al., 1999; Nelson, 1992). The generic
term for a large group of syndromes due to and imbalance between the perfusion,
and demand by the heart for oxygenated blood. Essentially, the heart requires
more oxygen than is being supplied. Ninety percent of the time, the imbalance
is caused by atherosclerotic obstruction of coronary arteries (Cotran,
1999; Nelson, 1992). It is important to note that the clinical syndromes
that result from IHD are the end result of decades of silent, progressive
atherosclerotic change in the vessels, often beginning in childhood or
adolescence.
Some clinical syndromes that result from IHD include angina pectoris,
myocardial infarction, and chronic ischaemic heart disease.
Angina pectoris (angor- strangle; pectoris- chest)
is clinically characterised by chest discomfort, with the patient complaining
of sharp, squeezing, choking, knifelike sensations. This syndrome is
basically the result of a transient state of myocardial ischaemia lasting
from 15 seconds to 15 minutes, that fails to cause the cellular necrosis
required to treat it as an infarction (Cotran, 1999). The ischaemic
state is usually caused by an increase in stress such as exercise, emotion
or extreme cold.
Myocardial infarction (MI) (myo- muscle; kardial-
heart; infarction- to stuff) indicates a more severe blockage
than angina pectoris. Whereas angina is reversible (in terms of post-incident
recovery and healing), MI’s are not, because they are characterised
by ischaemic necrosis of myocardial fibres (Cotran, 1999). If the patient
survives the first 24 hours, then a range of complications can arise,
the severity of these will depend on which vessels were blocked; extent
of the blockage; overall state of circulation; and the local collateral
circulation. If one or several MI’s have occurred, the patient’s
heart will not operate as efficiently or effectively as it had previously,
the most common complication being arrhythmia (Cotran, 1999).
Chronic ischaemic heart disease is a classification of IHD whereby there
has been multiple ischaemic attacks to the heart that lead to progressive
heart failure. Usually there has been known attacks if angina, MI’s
or sometimes iatrogenically as a result of bypass surgery. The heart
typically undergoes hypertrophy of unaffected myocardium, as a result
of working harder to compensate.
2) Hypertensive Heart Disease
Hypertensive heart disease my be classified as systemic or pulmonary,
and is the response by the heart to an increase in pressure.
Systemic Hypertensive Heart Disease effects the chambers on the
left side of the heart, and to be diagnosed requires a minimum criteria
of a) presence of left ventricle hypertrophy in the absence of another
pathology that may cause it, and b) history or evidence of hypertension.
It is caused by long-term systemic hypertension, and may be asymptomatic,
with left ventricular wall hypertrophy only detectable by ECG. Hypertrophy
occurs as an adaptive response to pressure overload caused by the hypertension.
The pressure in the aorta is greater than normal, and therefore the
left ventricle has to pump harder to overcome the “reverse”
pressure being applied by the aorta. The heart undergoes hypertrophy
without ventricle dilation, resulting in a decreased contractile ability
and subsequent failure. Systemic hypertensive heart disease often only
comes to the attention of the patient by the onset of atrial fibrillation,
or congestive heart failure, or both (Cotran, 1999). Depending on the
severity, duration and management of the hypertension, patients may
endure normal longevity and die of unrelated causes. In severe or mismanaged
cases, patients may develop IHD due to hypertension-induced atherosclerosis,
CVA, progressive renal damage, or congestive heart failure.
Pulmonary Hypertensive Heart Disease, or Cor pulmonale, is the right-sided
complement of systemic hypertensive heart disease, resulting in right
ventricle hypertrophy, dilation and failure. These changes are secondary
to pulmonary hypertension caused by of the lungs or pulmonary vasculature.
Importantly, this definition does not include right-sided dilation due
to left-sided heart diseases, or congenital heart diseases. Cor pulmonale
can be acute or chronic and occurs because of abnormality in the pulmonary
region, most commonly Chronic Obstructive Pulmonary Disease (Cotran,
1999). Acute cases are induced by sudden massive pulmonary embolism,
where chronic cases develop right ventricle hypertrophy and dilation
due to constant pressure overload from obstructed pulmonary arteries
Other types of heart disease include valvular heart disease; nonischaemic
myocardial disease; and congenital heart disease.
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