In this final article in our series on syncope, we will consider, in general terms, the treatments used for the major varieties of syncope: cardiac syncope and vasovagal syncope.
The treatment of cardiac syncope
As we have noted, two general types of heart problems can produce syncope – obstructive lesions, and heart rhythm disturbances.Obstructive lesions (such as valvular heart disease, obstructed blood vessels, or cardiac tumors) can intermittently block the flow of blood through the heart, causing loss of consciousness. The treatment of obstructive cardiac lesions is surgical – if there is a mechanical obstruction to blood flow, that obstruction must be physically removed. The extent, chances of success, and risks of such surgery depend on the nature of the obstruction. But when an obstruction is impeding blood flow to the extent that syncope occurs, as a general rule surgery is imperative, whatever the risks involved.
Heart rhythm disturbances that produce syncope fall into two broad categories: bradycardia and tachycardia.
Bradycardia, cardiac arrhythmias that produce a slow heart rate, can cause syncope when the heart rate becomes so slow that insufficient blood is pumped to the brain, and consciousness can no longer be maintained. Fortunately, implanting a cardiac pacemaker can easily treat this problem.
Tachycardias are heart rhythm disturbances in which too many electrical impulses are produced by the heart, thus causing the heart to beat too rapidly. While there are many kinds of tachycardia, only two produce syncope with any regularity – ventricular tachycardia (VT) and ventricular fibrillation (VF).
One treatment used for both VT and VF is antiarrhythmic drugs. These drugs, as a class, tend to be quite toxic, and their effectiveness in completely eliminating VT and VF is relatively poor. Therefore, antiarrhythmic drugs should be used only rarely as the primary treatment for patients whose VT or VF has produced syncope.
A second form of treatment is ablation. Ablation consists of carefully mapping the electrical system of the heart (either in the electrophysiology laboratory or in the operating room), locating the part of the electrical system that is causing the arrhythmia, and ablating the offending area (by freezing it, burning it, or surgically excising it). Unfortunately, most forms of VT are very difficult to localize to a specific “culprit” area. This means that ablation is only infrequently an option for VT (and never for VF).
The third and most effective treatment for both VT and VF is the insertion of an implantable defibrillator. In nearly 20 years of clinical use, the implantable defibrillator has proven itself to be extraordinarily effective in automatically stopping lethal tachycardias, and preventing sudden death. Because of the remarkable effectiveness of the implantable defibrillator (and the disturbing ineffectiveness of other methods of therapy), this device is, by far, the best choice for patients who have had VT or VF that has produced syncope.
