Skipping hearts

An arrhythmia can signal trouble in individuals with preexisting heart diseases

Many a love song has been written about the heart that skips a beat and another that beats too fast, but there is nothing romantic about a heart that beats out of tune. An arrhythmia is the unromantic irregularity of the heartbeat. Though most arrhythmias are not life-threatening, some can be dangerous in individuals with preexisting heart diseases.

The beating of the heart

The heart has an internal electrical system that sends a signal from the top of the heart to the bottom, causing the heart to contract—or beat—and pump blood. Just like the wiring of any complex piece of machinery, several components function together to make this process work, and any glitch in any part of the system can cause the heart to beat irregularly, resulting in arrhythmias. When the heart is unable to beat properly, it cannot pump blood effectively. When the heart does pump blood effectively, the organs in the body that rely on the heart may become damaged or fail entirely.

To understand why arrhythmias occur, it is necessary to navigate the more technical aspects of the heart. A heartbeat begins in the sinoatrial node (also known as the sinus node or SA) of the heart and is sometimes referred to as the “natural pacemaker” because it initiates a heartbeat. In some circumstances, all tissue of the heart can send out a signal that causes a heartbeat, and when this happens, it interrupts the regular rhythm of the heart. Furthermore, the human body being as amazing as it is, there are also “back-ups” that take over the job of causing a heartbeat when the sinus node isn’t working properly or there are problems with the heart’s electrical system.


Arrhythmias can be caused by the sinus node malfunctioning, problems in the electrical pathway of the heart—like a frayed wire of an appliance—or another part of the heart taking over the job of the sinus node, creating a whole new rhythm that interferes with the regular pumping of the heart.

Fixing a skipping heart

Medications are available to speed up and slow down the heart, and usually a combination must be taken to counteract possible side effects. Some doctors may perform a cardioversion—applying an electrical shock to the heart—to quickly establish a normal rhythm. A less invasive version of this procedure is a cardiac ablation, where a catheter is inserted into the heart muscle and a burst of radiofrequency energy destroys the muscles causing the arrhythmia.

For patients with more severe cases of arrhythmia, complications from medications, aging or diseased hearts, or more pronounced symptoms (like fainting), doctors recommend a pacemaker, to replace the natural sinus node of the heart that is no longer doing its job. This is a small device—a combination of a programmable computerized chip and energizing battery--implanted in the heart that uses electrical pulses to prompt the heart to beat at a normal rate, sort of a tiny built-in defibrillator.

The implantation of a pacemaker usually involves a local anesthetic and a small incision on the left shoulder, through which the pacemaker is inserted. The leads, which attach to the heart muscle, are threaded through a vein at the collarbone. The device is then tested and programmed specifically for the particular type of arrhythmia. Most pacemaker batteries last between five to ten years and regular follow-ups will be scheduled after the initial implantation to ensure that the pacemaker is working as it should.

Sources:

• http://www.heart.org/HEARTORG/Conditions/Arrhythmia/Arrhythmia_UCM_002013_SubHomePage.jsp
• http://www.webmd.com/heart-disease/guide/heart-disease-abnormal-heart-rhythm
• http://www.nhlbi.nih.gov/health/dci/Diseases/arr/arr_whatis.html

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