Hypertrophic Cardiomyopathy (HCM) is a genetically mediated, structural defect in the heart which results in an abnormally thickened muscular septum between the right and left ventricles. This thickened septum impedes blood flow out of the ventricles, particularly between the left ventricle and aorta (which supplies blood to the rest of the body). This most commonly presents as fainting spells in young adults, during exertion and can also result in sudden cardiac death.
Management of HCM is usually initiated with medications. If medicines fail to control the condition or in case of severe abnormalities in the structure and function of the heart, procedures such as septal myectomy and septal ablation are considered. Both procedures involve the removal of a part of the thickened septum to establish adequate blood flow, however, they differ in their approaches and have their own set of advantages and disadvantages which need to be considered before making a choice.
Investigations and Tests
The following tests are performed in all individuals with HCM considered for a procedure
- Echocardiogram: This test utilizes ultrasound waves to examine the structure of the heart. The blood flow between different heart chambers and into the blood vessels can also be measured. This is important in providing information on the blood flow between the left ventricle and the aorta in patients with HCM.
- Chest X-ray
- Electrocardiogram: This measures the electrical activity in the heart. It is recorded using skin electrodes placed on the chest
- Routine Blood investigations
- Cardiac Catheterisation: This test involves inserting a catheter (thin tube) into the heart chambers. The catheter is inserted through one of the blood vessels in the arm and pushed up to the heart. A dye inserted through this tube can be visualized using X-ray and allows for visualization of the cardiac blood supply. With an additional probe at the tip of the catheter, pressure differences between different parts of the heart can also be measured.
Septal myectomy is a surgical procedure with open-heart surgery, where the chest is opened up to reveal the heart. The septum is accessed by passing through various heart structures. A portion of the thickened septum is cut surgically to establish normal blood flow from the left ventricle to the aorta, after which the chest is closed again.
Prior to the surgery, a complete evaluation of the individual is done. As this procedure requires general anesthesia, an anesthetist is involved in care. Routine medications including those for other chronic illnesses are evaluated and may be modified prior to surgery. The individual will be instructed to avoid eating after midnight.
During the procedure
On the day of surgery, the individual would be placed under general anesthesia after which the surgeon would begin the procedure.
The chest is opened up by cutting through the sternum (breast bone) in the center. The individual is placed on a heart-lung machine. This machine carried out the work that is normally done by the heart and lungs (pumping blood and breathing). This allows the surgeons to handle a ‘still heart’.
The heart is visualized and the septum is accessed through passing through the heart muscles. The extra portion of the septum is removed from the left ventricle outflow tract, providing adequate blood flow to the aorta.
Often, surgeons would also plan to correct any defects in the mitral valve (the valve between left atrium and ventricle) as this is commonly distorted in individuals with HCM, causing a leak across the valve.
After the procedure is complete, temporary pacing wires may be left in place. This is done to provide electrical support to the heart. A chest drain is left to drain out excess fluid after which the chest is closed and sutured. The individual is then brought out of anesthesia and taken to a recovery room.
The entire procedure can take between 3 to 6 hours.
After the procedure
Regular monitoring of vitals with a focus on cardiac monitoring is carried out by specialists in an intensive care setting. There may be a pain in the chest, especially over the sternum where the chest was opened.
Occasionally, there may be a requirement for cardiac pacing and some individuals may have abnormal cardiac rhythms, requiring an ICD (implantable cardioverter-defibrillator), which records and corrects these abnormal rhythms.
Special instructions for follow up and wound care are provided, along with detailed instructions regarding medications. After 5 to 7 days, the individual is ready to be discharged.