Our heart rate is regulated by specialized tissue that coordinates the electrical activity of the heart. In some cases, this tissue, known as the conduction system, is unable to function properly due to a heart attack, viral infection of the heart or advanced age. If dysfunction of the conduction system persists, the heart rate can drop to an unsafe range and electrical impulses from the top chambers of the heart may not make it to the bottom chambers, leading to complete heart block. Sometimes, medications can boost the heart rate and improve conduction, but if not, implantation of an artificial pacemaker may be required. Like any invasive procedure, there are potential side effects and complications associated with pacemaker implantation.
Blood Vessel or Lung Damage
Though most pacemakers today are implanted transvenously, meaning they're inserted by vein without the need for open-heart surgery, the procedure can still cause damage to blood vessels and other structures near the heart. If a blood vessel is accidentally pierced, bleeding may not be obvious initially. In this case, the blood slowly accumulates, forming a "pocket hematoma". Most of these hematomas gradually go away on their own, but rarely, the pacemaker site may need to be reopened in order to drain the blood.
Similarly, the outer lining of lung may be punctured during pacemaker placement. In most cases, the puncture, or pneumothorax, is small, doesn't cause any symptoms and resolves on its own. If the pneumothorax worsens or leads to symptoms, doctors may place a chest tube to allow the lung to re-expand so the person can breathe normally.
Any time an incision is made in the protective barrier of the skin, there is a possibility of infection. Fortunately, antibiotics given prior to pacemaker placement have dramatically reduced the risk of wound infection. When infection does happen, signs include persistent pain and tenderness at the wound site, redness around the incision and fever. Infections are typically treated with powerful antibiotics that prevent the organism from spreading to the pacemaker and heart itself. If the infection does progress, it leads to pacemaker-associated endocarditis. In endocarditis, small deposits of infectious material cling to the pacemaker wires and can spread to the heart valves. If this takes place, the device has to be surgically removed.
Abnormal Heart Rhythms
In rare cases, a patient may experience abnormal heart rhythms after pacemaker implantation. When a pacemaker malfunctions, it can sometimes induce pacemaker-mediated tachycardia which causes the heart to beat extremely fast. The pacemaker can usually be reprogrammed so the heart beats within a normal range. Symptoms of an abnormal heart rhythm include palpitations, chest discomfort, difficulty breathing, nausea and dizziness.
Structural Heart Damage
Rarely, pacemaker implantation can damage the heart itself. As the pacemaker wires are inserted into the lower chamber of the heart from the top chamber, the tricuspid valve may be accidentally injured, causing the valve to leak. If the pericardial tissue surrounding the heart is punctured, blood accumulates and can prevent the heart from beating properly. This is known as cardiac tamponade and is a medical emergency that requires prompt evacuation of the blood.