Inherited Cardiac Conditions
Updated: Mar 24, 2020
The most common inherited heart conditions are cardiomyopathies and channelopathies.
Channelopathies arise from abnormal ion channels affecting the flow of ions which can result in abnormal heart rhythms. These include long QT syndrome (LQTS), brugada syndrome, catecholaminergic polymorphic ventricular tachycardia (CPVT) and progressive cardiac conduction defect (PCCD).
One might consider assessing for the possibility of an inherited cardiac condition if a member of the family has an inherited heart condition; or there’s a history of cardiac arrests or premature deaths in the family; or death in the family is hard to explain or thought to be caused by a faulty gene.
Hyperytophic cardiomyopathy HCM is a heart muscle wall condition involving thickening abnormal of the muscle wall.Thickening of the muscle results in increased stiffness of the muscle and reduced efficiency of the heart wall contractility. Reduction in this efficiency affect the ability of the heart to function as good pump to pump blood throughout the body to all the other organs.
Common symptoms include shortness of breath,chest pain, palpitations, light headedness and fainting. Other heart conditions that can arise as a result of HCM include abnormal heart rhythms or arrythmias either fast or slow rates including heart block and heart failure.
About 1 in 500 of the UK population has the condition, although most people who have it have few, if any, symptoms.
Dilated cardiomyopathy DCM is a heart muscle condition involving the ardiac chambers to become stretched and dilated. A non-medical description is a 'baggy' heart. As the heart muscle becomes weak, thin or floppy, the ability of the chambers to pump blood around the body efficiently is reduced. Inefficient blood pumping of the heart can lead to several symptoms.
Common symptoms include shortness of breath, excessive tiredness, palpitations and swelling of the ankles and abdomen. Other heart conditions that can arise as a result of DCM are similar to the above. These include heart failure and abnormal heart rhythms or arrythmias - either fast or slow rates including heart block.
Some forms of DCM can be inherited. Other types can arise following either a viral infection, uncontrolled high blood pressure, problems with the heart valves, excessive amounts of alcohol consumption or in certain cases pregnancy related.
Arrhythmogenic right ventricular cardiomyopathy ARVC is a rare disease of the heart muscle. Here the problem arises from a protein that is meant to hold the heart cells together. In people with ARVC, these proteins do not develop properly and therefore cannot hold the heart muscle cells together. The muscle cells become detached and fatty deposits build up in an attempt to repair the damage.
ARVC usually affects the right side of the heart, and in some cases it can affect both sides. The changes to the heart muscle mean the walls of the ventricle - one of four chambers in the heart - become thin and stretched. This reduces the efficiency of the heart working as a pump and therefore reduces the amount of bood being pumped to the rest of the body.
ARVC can also cause abnormal heart rhythms, as the heart’s normal electrical impulses are disrupted as they pass through areas of damaged and scarred muscle cells. It usually takes many years for this to happen so most people are not diagnosed until later in life.
The condition is usually progressive.
Long QT syndrome LQTS is a rare inherited condition caused by ion channel abnormalities affecting the flow of ions and therefore a change in the normal cellular conduction activity. It can cause abnormal heart rhythms (arrhythmias).
Two main channel abnormalities that cause LQTS include the Sodium , Na and Potassium, K channels. There are number of types of Long QT syndromes now described. Commonly the potassium channel LQTS carries a risk of sudden death if one is startled or awoken suddenly whilst the sodium channel LQTS increases one's risk of sudden death during sleep. The risk of sudden cardiac death is higher if one has blackouts, a very long QT interval on the ECG, a sodium channel mutation or previously had a cardiac arrest in the presence of unobstructed coronary arteries and a normal cardiac shape and dimension on heart imaging.
In certain cases some medications can prolong the QT interval and unmask this condition. Patients with known long QT intervals must avoid these drugs. A list of these drugs are listed on the following website :
Patients with known LQTS should avoid stress, a sudden noise, strenuous exercise (particularly swimming) and a slow heart rate during sleep.
Brugada syndrome is a rare inherited ion channel heart condition that involves a disruption in the flow of ion channels. It commonly affects the sodium channel.
Abnormal cellular ion balance disturbs the cellular electrical properties which once again can lead to rhythm disturbances. Arrhythmias that arise here can be fast and in some cases do lead to a very fast heart rate where the heart is no longer able to contract normally and therefore the blood supply to the rest of the body is acutely disrupted - leading to a cardiac arrest.
Some symptoms include light-headedness, dizzy spells, blackouts and palpitations. Certain conditions like having a temperature (having a fever) or being dehydrated or alcohol consumption can bring on some of the symtoms in patients with Brugada.
Cathecholaminergic Polymorphic Ventricular Tachycardia, CPVT is a rare inherited heart rhythm disturbance found in young people and children.
This condition arises from an abnormality of the proteins that regulate the release of calcium ions. If these proteins function abnormally, it can lead to a rise in the level of calcium inside heart cells. An imbalance in the ions does affect the electrical propeerties of the cell and once again cause very fast heart rates.
The most common symptoms of CPVT are blackouts, palpitations and dizziness. These can be brought on by strenuous physical activity and heightened emotions, which can cause an increase in the amount of adrenaline running through the blood.
Progressive cardiac conduction defect PCCD is a rare inherited heart rhythm disturbance where the heart’s electrical impulses are conducted very slowly. Over time, this can lead to complete heart block – also known as third degree heart block.
Most common symptom include dizziness, feeling lightheaded and losing consciousness.