With the present modern day medicine cardiology practice we are saving more and more patients of heart attacks. Treatments like primary angioplasty and modern newer medicines have increased the survival of heart attacks patients. But one of the major effects of these treatments is that we are having more and more patients with damaged hearts who are surviving but with limited stamina and very high mortality due to other complications like arrhythmias (presenting as cardiac arrest or sudden cardiac death.) Patients with heart disease of any etiology (Including Cardiomyopathies) with low ejection fraction (Pumping power of heart) less than 35 % have significant increased risk of dying suddenly due to arrhythmias. Medicine at best have very limited role. Fortunately now we have devices named AICD (Automatic internal cardioverter defibrillator) and Biventricular pacemaker (CRT) and a combination of these two Combo devices to handle these situations.
AICD is a small device like pacemaker and is implanted by minor surgical procedure over the chest. The lead goes inside the heart and is attached to right ventricle apex. A Second lead is connected to right atrium. The device continuously senses each beat of the heart and if the beat goes below the limit set it acts as a pacemaker and starts pacing the heart but if the heart starts beating dangerously fast it gives shock inside and cardiovert/defibrillate the heart to restore the normal rhythm preventing sudden cardiac death. Lots of trials have been conducted. In all trials for which results have been reported, the death rate was significantly lower in patients who received ICDs. The improvement in survival was so significant that some studies were stopped early so that all patients could have the option of receiving ICD therapy. ICDs are 99 percent effective in preventing cardiac arrest.
Who is a candidate for an AICD?
The American College of Cardiology and the American Heart Association, along with representatives of NASPE, have developed guidelines to help physicians and patients decide whether an ICD is the best treatment for an individual at risk for SCD. For example, it is agreed that ICD therapy is of benefit for:
BIVENTRICULAR PACEMAKERS (CRT)
- Secondary Prevention: This includes individuals who have suffered a prior cardiac arrest or who experience spontaneous, sustained episodes of ventricular tachycardia (VT) that is not self-correcting), especially if they also have episodes of unexplained fainting. VT is a too-rapid heartbeat that can lead to VF.
- Primary Prevention: This is treatment for patients who have never experienced the deadly heart rhythm disorders that lead to SCD, but have significant risk factors for the conditions. This includes certain patients with an ejection fraction of less than 35% percent and documented episodes of VT that are self-correcting and cause no adverse symptoms, but in whom sustained VT can be induced during the electrophysiology study. Ejection fraction is a measure of the amount of blood pumped out of the heart with each beat. An ejection fraction below 35% is considered abnormal. Vice President Cheney's ICD is for primary prevention.
is a small device like pacemaker and is implanted by minor surgical procedure over the chest. three leads are inserted inside the heart. One lead is connected to right ventricle apex. A Second lead is connected to right atrium. Third lead is passed through coronary sinus into lateral cardiac vein to stimulate Left ventricle. Both ventricles are stimulated simultaneously to overcome dyssynchrony to improve Left ventricular Ejection Fraction. Lot of trials have been conducted and have shown significant morbidity and mortality benefit.
Patients with Low LVEF and LBBB or documented ventricular dyssynchrony should be investigated for need of Biventricular pacemaker and AICD (Combo Device).
This device has AICD and biventricular pacemakers combined. So this can revert ventricular dyssynchrony and can revert dangerous arrhythmias to prevent sudden cardiac death.
We have implanted 200 AICD devices, and 20 combo devices in Maharaja Agrasen Hospital. The limited number is due the high cost of the machine (Around 3.5 to 5 lakhs rupees for AICD and 7.5 to 10 lakhs for combo device. Few of our patients have increased their LVEF from 25 to 50% almost a miracle solely because of device because if you turn off the device the LVEF fell to 25% again.
Take Home Message
Any patient with heart disease with Low ejection fraction less the 35% with arrhythmias/Syncope/Dizziness episodes etc should be investigated for need of AICD. Any patient with heart disease with Low ejection fraction less the 35% with arrhythmias/Syncope/Dizziness episodes etc and LBBB or documented ventricular dyssynchrony should be investigated for need of Biventricular pacemaker and AICD.