Cardiac
Inherited Disease Registry
Hypertrophic
Cardiomyopathy
An inherited disease is one, which can be passed down
through a family, from an affected parent, to a child. Each child born to a
parent, who carries the gene for Hypertrophic Cardiomyopathy has a 50% chance
of inheriting the gene for this condition.
There is no way to predict who in a family will carry the gene. There is also no way of predicting the
severity of the disease, and some individuals may inherit the gene but may not
develop the condition
Familial Hypertrophic Cardiomyopathy is one of the more
common Cardiac Inherited diseases occurring in approximately one in 500 in the
general population.
Hypertrophic Cardiomyopathy is abbreviated HCM, but also
includes other abbreviations FHC, HOCM and IHSS, which are just different terms
for the same disease.
In hypertrophic cardiomyopathy (HCM), the growth and
arrangement of the heart muscle fibres are abnormal, which may lead to abnormal
thickening of the left ventricular wall and septum. Because the muscle fibres become disorganised the process of
fibrosis occurs between and around muscle fibres. The result can be gradual thickening of the heart walls in
particular the wall which lies between the two main pumping chambers called
ventricles. The left ventricular septum
which is the name of the wall which separates the right and left ventricles
(the hearts’ main pumping chambers) can become so thick that it begins to
prevent blood from entering the heart, which means that the heart does not get
adequately filled with blood.
In some individuals with hypertrophic cardiomyopathy there
is also obstruction to blood flow as blood is pushed out of the heart. This may
lead to a situation where the blood supply to the heart muscle itself (the
blood which is supplied to the heart muscle through the coronary arteries) may
be reduced particularly during exercise or strenuous activity.
The function of the Mitral valve (the
valve which allows blood to flow between the left atrium (a filling chamber)
and left ventricle (a pumping chamber) may also be impaired by this abnormal
thickening and therefore be less effective.
2) What are the symptoms
of Hypertrophic Cardiomyopathy?
Many individuals with HCM have no symptoms. Symptoms can appear in childhood or
adulthood. Warning symptoms are often
breathlessness and or fatigue or excessive tiredness. Other symptoms may include fainting during physical activity,
strong rapid heart beats which feel like a pounding sensation in the chest, and
chest discomfort that feels like a heaviness in the chest (commonly occurring
with exercise). In some cases the first
and only symptom of the disease will be sudden death (sudden unexplained death)
where a young person in the family collapses and dies. Often sudden death episodes will occur
during exercise.
Many tests including electrocardiogram (ECG), may help
diagnose the condition by detecting changes in the electrical activity of the
heart as it beats and echocardiography (Echo) uses an ultrasound beam to
measure the internal chambers of the heart, through the skin by putting gel on
the chest and moving a probe over the skin surface. It also assesses the overall ability of the heart to function
normally. These tests usually identify the majority of cases of HCM though the
only definitive tests are genetic analyses (which are currently not available
routinely). People may be asked to provide a family history, including
instances where individuals may have died suddenly or suffered from any other
illness affecting the heart during their lives. Your specialist will also undertake a detailed examination of
your cardiovascular system, when you attend your clinic appointment, and this
will usually be done before or in conjunction with the basic screening tests
such as ECG and Echo.
4) Research into
Hypertrophic Cardiomyopathy
During the 1990's much has been learned
about the genetic mutations that contribute to the condition. At present these genetic analyses are time
consuming and very expensive. Doctors
researching this condition hope one day to offer more simple tests. This would ensure early diagnosis,
treatment, and ongoing screening tests so individuals at risk of inheriting
this condition can be investigated and monitored from an early age.
By creating a registry of patients’ and
families, with HCM, we hope to be able to contribute to early screening and
treatment for HCM. It is also our goal,
to provide an up to date source of information to families with Hypertrophic
Cardiomyopathy.
5) Treatment for
Hypertrophic Cardiomyopathy
Although there is no cure currently available for
Hypertrophic Cardiomyopathy, there are good ranges of treatment options
including medications that help to relieve the symptoms of exercise intolerance
and chest discomfort. These medications also slow the heart down, enabling it
to fill with blood more easily. Other
treatment options also include, Pacemakers, implantable defibrillators,
operations that reduce obstruction to blood flow, and in advanced stages of the
disease cardiac transplantation may be offered. These treatment options are very specific to the problems you or
your family member is experiencing with HCM, your specialist will discuss these
options with you and recommend the best options for dealing with your
particular case. Other things that can
assist the heart are reducing alcohol and salt intake, and trying to keep from
gaining excess weight where possible.
Heavy physical work, or strenuous exercise may also need to
be avoided, if you have any questions regarding your ability to undertake any
specific activity, please discuss this with your specialist at your clinic
appointment.
6)
Additional
Information
If you have any questions after reading
this information please contact the registry co-ordinator/ and or your
Specialist.
If you have any
queries regarding your rights as a participant in the Cardiac Inherited Disease
Registry you may phone the Health Advocate Trust: Phone (09) 623 5799 0800 555
050 Northland to Franklin
Or Contact Mata
Forbes RGON; Co-ordinator/Advisor, Maori Health Services, Auckland District
Health Board, Auckland Hospital Grafton; Mobile 021 348 432
This study has
received Ethical Approval from the Auckland Ethics Committee: AKX/02/00/107