Dr Carl Shakespeare consultant cardiologist  
       
 
   
consultant cardiologist
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Hypertrophic cardiomyopathy:

This is an important condition because it tends to be hereditary in about 50% of cases. It is due to a genetic defect of heart muscle that develops abnormally from birth. The diagnostic features of this abnormal muscle may not be apparent using heart scans until the mid teenage years, but is generally considered if there is a family history of it. Generally it may not manifest itself with symptoms either at all, or until later in early adulthood. The abnormal heart muscle thickens (that’s what hypertrophic means), usually near the outflow of the pumping chamber of the left ventricle. In such cases it may cause a heart murmur, which is the sound made when there is turbulence generated by blood being pumped past the thickening. This can be heard with a stethoscope. More uncommonly the abnormal thickening can occur towards the tip of the left ventricle (apical hypertrophy) or more diffusely around the whole of the ventricle.

In the more common version, the restriction to heart pumping may cause dizziness or collapse, especially after exercise, and should be considered as a diagnosis especially in young adults complaining of such symptoms. The abnormal muscle unfortunately can cause abnormal electrical circuits that can cause serious forms of arrhythmia. Symptoms of this could include palpitations, dizziness, and collapse. In young adults and beyond, chest pain, angina like symptoms and breathlessness can be presenting symptoms.

The main concern of this condition is that occasionally it can be the cause of sudden death especially in younger people. Thus early identification is important to either rule it out, or begin treating it effectively. In some cases, genetic testing may help identify whether there is an inherited form of the condition. However as new genetic mutations are constantly being identified, one cannot necessarily exclude the condition.

 


Crucially, if there is a family history, especially of collapses, or unknown causes of death in other family members, blood relatives need to have this condition excluded. In earlier times the general perception was that this was a lethal condition. However, more recent research has revealed that this condition has a much more varied outlook. The finding that large numbers of residents in old people’s homes that have the condition is a testament to this!

The diagnosis is usually made by listening for a heart murmur, performing an ECG, and undergoing an echocardiogram. The difficulty in young children and until mid-teenager-hood, the ECG and echocardiogram may be normal, thus require sequential re-evaluation every five years until the heart is fully formed (roughly by the mid teens). Thus the difficulty is in trying to diagnose the condition in pre-teenage years, where unfortunately the mortality is highest. Gene typing may offer some help, but importantly regular clinical review is the mainstay here.

In grown adults, there is a differential diagnosis of other causes of heart muscle thickening that can make the diagnosis of hypertrophic cardiomyopathy difficult. Most commonly, hypertension can cause thickening of heart muscle. This generally does not occur in younger adults. However, in young athletes, athletic heart syndrome can cloud the diagnosis too. In this case, high levels of exercise can cause heart muscle to thicken causing hypertrophy. Using echocardiography and increasingly using cardiac MRI, the diagnosis can usually be resolved.

If the diagnosis of hypertrophic cardiomyopathy is made then it is first characterised. If the problem involves prominent outflow obstruction, the condition is termed “hypertrophic obstructive cardiomyopathy”, or HOCM for short. Otherwise it is termed just hypertrophic cardiomyopathy. The main objective now is for risk stratification of the condition. This is very important in order to comfortably reassure the majority of patients. This usually involves a 24-48 hour ECG to exclude any tendency towards significant arrhythmia. Also an exercise ECG can be performed, and patients can be reassured if there is a satisfactory increase in blood pressure with exercise can be demonstrated. Other more esoteric tests can be employed such as analysing heart rate variability, but these are less common.

Once risk stratification has been completed, the majority of patients can be reassured, although kept under regular clinical review. For the minority of patients in whom significant potential risk has been identified, empirical treatment with drugs such as beta blockers or anti-arrhythmic medication is considered. Such medications may treat underlying symptoms of arrhythmia, or just provide cardio-protective insurance against adversity. Most cases of the obstructive version of the condition do not require intervention. However, in some patients in whom the obstruction is considered the cause of dizziness or collapse (and arrhythmia excluded), then surgical removal (myomectomy) or chemical ablation (alcohol ablation) of the obstruction is sometimes performed.