Cardiac Resynchronisation Therapy(CRT) also known as bi ventricular pacing is a breakthrough treatment for patients suffering from Congestive Heart Failure(CHF). For over 20 million patients worldwide who suffer from Congestive Heart Failure this comes as lifesaver, for in the past the patients had limited treatment options like lifestyle changes, medication and heart surgery all of which seldom proved effective for more advanced stages of the disease.
Congestive Heart Failure occurs when the heart muscles are weakened due to various reasons like Coronary Artery Disease, inherited defects, toxins like alcohol or other viral diseases. This causes irregular muscle contractions in the heart resulting in inefficient pumping of blood. Cardiac Synchronisation Therapy works by correcting the irregular muscle contractions and relieving the patient of the symptoms of Congestive Heart Failure. Cardiac Resynchronization Therapy improves the coordination of the contractions using technology similar to that used in pacemakers and implantable cadioverter devices.
The anatomical section of the heart reveals 4 chambers, the two upper atria and the two lower ventricles. Blood is pumped by these 4 chambers and an electrical conduction system is responsible for their synchronised contractions. This electrical system consists of a Sino atrial node or SAN, this is where the electrical signal originates. This signal from the SAN spreads through both the atria which contract and thus push blood into the ventricles. From there the signal propagates to the ventricles by means of a specialised network known as the right and left bundle branches. These stimulate both the ventricles to contract simultaneously thus providing for optimal pumping of blood to the lungs and the rest of the body.
Sometimes an abnormality occurs in the electrical conduction system causing an intra ventricular conduction delay or a bundle branch block. Thus the electrical signal to one of the ventricles is delayed by a fraction of a second resulting in asynchronous contraction of the ventricles, i.e. the ventricles do not contract simultaneously. This further accounts for reduced pumping ability for the heart muscle which is already weakened.
Cardiac Resynchronisation Therapy works using a principle similar to that used in normal pacemakers. CRT restores the coordinated pumping action of the ventricles by overcoming the conduction delay caused by the bundle branch block. Cardiac resynchronisation therapy achieves this by providing the signal to both the ventricles simultaneously using a Cardiac Resynchronisation Therapy(CRT) device. What separates the CRT device from a conventional pacemaker is that they pace both ventricles simultaneously while the latter paces only the right ventricle.
Cardiac Resynchronisation Therapy can relieve symptoms of heart disease, increase the patient’s exercise capability and increase overall well being for patients suffering from moderate to severe heart failure. Further research has shown that CRT improves the functional and anatomical aspects of the heart, in the case of dilated cardiomyopathy it reduces the size of the dilated left ventricle and enhances metabolism. Cardiac Resynchronisation Therapy drastically improves the chances of survival for the patient.