Lyme disease, a condition caused by the bacterium Borrelia burgdorferi, is primarily transmitted to humans through the bite of infected blacklegged ticks. While often associated with skin rashes and joint pain, this tick-borne illness can also impact various organ systems, including the heart. Lyme disease can affect the heart, a manifestation known as Lyme carditis.
How Lyme Disease Affects the Heart
Lyme carditis develops when the Borrelia burgdorferi bacteria infiltrate the tissues of the heart. This bacterial presence triggers an inflammatory response within the heart muscle, a condition called myocarditis. The inflammation can disrupt the heart’s normal functioning, particularly its electrical conduction system.
The most common cardiac complication of Lyme disease is heart block, specifically atrioventricular (AV) block. This occurs when the electrical signals, which coordinate the beating of the heart’s upper and lower chambers, are slowed or completely blocked. The severity of heart block can range from mild (first-degree) to severe (third-degree, or complete heart block), and it can fluctuate rapidly.
While the precise mechanism is still being studied, it is believed that both the direct invasion of heart tissue by the bacteria and the body’s immune response contribute to this damage. In some cases, cross-reactive antibodies produced by the immune system may inadvertently attack cardiac tissue.
Recognizing Heart Symptoms of Lyme Disease
Individuals with Lyme carditis may notice a range of symptoms. Common indications include lightheadedness and dizziness, which can sometimes lead to fainting episodes. Shortness of breath is another common symptom.
Patients might also describe heart palpitations, a sensation of a racing, pounding, or fluttering heart. Chest pain can also occur, varying in intensity. These cardiac symptoms often appear alongside other general Lyme disease signs, such as fever, body aches, or a characteristic expanding rash known as erythema migrans, though the rash is not always present in cases of Lyme carditis.
Diagnosis and Treatment of Cardiac Lyme
Diagnosing Lyme carditis typically involves a combination of clinical evaluation and specific tests. An electrocardiogram (ECG or EKG) is a primary tool used to detect heart block and other electrical abnormalities. An echocardiogram may also be performed to assess the heart’s overall function and structure.
Blood tests are used to confirm Lyme disease, usually involving a two-step serologic testing method. An enzyme-linked immunosorbent assay (ELISA) is typically the initial test, followed by a Western blot assay if the ELISA results are positive or borderline. Prompt antibiotic treatment is crucial.
Treatment usually involves a course of antibiotics, such as intravenous ceftriaxone for more severe cases or oral doxycycline or amoxicillin for milder presentations. The duration of antibiotic therapy typically ranges from 14 to 21 days. In instances of severe heart block that causes symptoms or hemodynamic instability, a temporary pacemaker may be necessary to regulate the heart’s rhythm until the antibiotics take effect.
Recovery and Outlook
The outlook for individuals diagnosed with Lyme carditis is generally favorable with timely and appropriate treatment. Most cases of heart block associated with Lyme disease resolve completely with antibiotic therapy. The resolution of heart block can occur relatively quickly, often within days to weeks of starting antibiotics.
While recovery is typically complete, some individuals may require continued monitoring by a healthcare provider. The transient nature of Lyme carditis means that permanent pacemakers are rarely needed. Early identification and treatment prevent complications and ensure full recovery.