What is CIDG and CIDRNZ?
CIDG is a national network of specialist clinicians and scientists working to prevent sudden death due to inherited heart diseases. The Cardiac Inherited Disease Registry N.Z. (CIDRNZ) is an ethically approved national clinical registry designed to track registrants (individuals and families with known cardiac inherited disease) or cases of young sudden death typically 1 - 40 yrs (referred by the Forensic Pathologists/Coroner).
Each CIDG member has their own employing hospital or District Health Board. Aside from the coordinators based within ADHB, Waikato DHB and Capital and Coast DHB, CIDG does not receive individual funding, but works within existing clinical systems to facilitate clinical screening for families across the country.
Which conditions does CIDG deal with?
The commonest familial heart conditions are long QT syndrome (LQTS), Brugada syndrome (BRS) and Hypertrophic Cardiomyopathy (HCM). CIDG also coordinates nationally the family and genetic investigation for sudden unexpected natural deaths in 1-40 year olds. CIDG works closely with the national forensic and coronial services.
Who leads CIDG?
The national clinical leader is Professor Jon Skinner, children's heart rhythm specialist, at Starship Children's Hospital.
Which doctors belong to CIDG?
A group of Clinicians from each region belong to CIDG. The majority are Cardiologists (heart doctors), Paediatricians, Geneticists and Pathologists. A current list is available on the CIDG website:www.cidg.org.nz
Is this just for children?
No, CIDG facilitates family screening for all family members. The heart tests are usually performed locally, in your local hospital. Children sometimes have specialised heart tests at the Starship Hospital and test results can be copied and sent to other specialists for opinion.
- Dr Tim Hornung, Paediatric Cardiologist
- Prof Jonathan Skinner, Paediatric Cardiologist
- Assoc Prof Warren Smith, Adult Cardiologist
Anybody can refer to CIDG for advice, including the patients themselves. The coordinator will help them link to a local clinician with the necessary expertise. We hold a weekly case meeting and discuss cases from around New Zealand, to provide Specialist opinion and advice.
Pathologists dealing with a sudden death who require advice should call Dr. Skinner in the first instance via the hospital switch board, or relay a question via the Clinical Coordinator (firstname.lastname@example.org); information for review can be sent to our team support/administrator (email@example.com).
Any clinician is welcome to phone or write for advice regarding their patients or families. It is almost always appropriate for the patient to be seen by a local specialist first.
Regarding written requests, please include as much detail about the family and the clinical presentation, including test results (particularly ECGs) necessary to permit an informed response.
Common Conditions / Procedures / Treatments
Exercise ECG or Exercise Test (ETT)
An ECG done when resting may be normal even when heart problems are present.
During an exercise ECG the heart is made to work harder and signs of heart disease may be unmasked. This test involves walking on a treadmill while the heart is monitored. The treadmill gets faster with time but can be stopped at any time. This test is supervised and interpreted by a doctor.
The test is helpful to detect many forms of inherited heart disease, especially long QT syndrome and CPVT (catecholaminergic polymorphic ventricular tachycardia). These conditions can sometimes cause sudden collapse and sudden death in young people, and are difficult to diagnose - the exercise test can help.
The heart rate is controlled by a complex electrical system within the heart muscle which drives it to go faster when you exert yourself and slower when you rest. A number of conditions can affect the heart rate or rhythm. Heart rate simply refers to how fast the heart is beating. Heart rhythm refers to the electrical source that is driving the heart rate and whether or not it is regular or irregular.
- Sinus rhythm is the normal rhythm
- Arrhythmia means abnormal rhythm
- Fibrillation means irregular rhythm or quivering of one part of the heart
- Bradycardia means slow heart rate
- Tachycardia means fast heart rate
- Paroxysmal means the arrhythmia comes and goes
- an electrocardiogram (ECG). This trace of the heart's electrical activity gives the diagnosis of the source of the arrhythmia. This is often normal at rest and more extensive testing is needed to try and catch the arrhythmia especially if it is intermittent.
- an Ambulatory ECG. This can be performed with a Holter monitor which monitors the heart for rhythm abnormalities during normal activity for an uninterrupted 24-hour period. During the test, electrodes attached to the chest are connected to a portable recorder - about the size of a paperback book - that's attached to a belt or hung from a shoulder strap.
In some forms of inherited heart diseases, genetic tests can be helpful when trying to identify which family members may be at risk of developing or carrying the condition.
Testing for long QT syndrome and hypertrophic cardiomyopathy is available.
It involves a blood test, from which the lab extracts DNA. The lab looks at the genes linked to the condition suspected. The DNA from the first family member to be tested has to undergo a sequencing of the genes - in effect looking for spelling errors in a number of genes. The test is highly specialised and time consuming. In 2010 a result is usually available within 3 months.
Once a mutation (spelling error) is found in one of the genes, this can be looked for in the other family members. This test is quicker - results take about 6 weeks.
Each person having the test must be counselled carefully first, by a specialist or clinical geneticist or associate, and the patient must give their informed consent, either via the CIDG network,or the clinical genetics service.
GPs and patients themselves may not order such tests.
This information has been provided by healthpoint.co.nz, helping people better understand and use New Zealand health services.