While some studies showed that cardiac manifestations in Lyme borreliosis occur in 0.5% to 4.0% of cases in Europe, some other studies have suggested incidences as high as 10% of untreated patients infected with Borrelia burgdorferi as having cardiac complications (1, 2). Lyme disease has a similar prevalence in both males and females and affects people of all ages, while some studies have shown slightly different Lyme carditis predominance depending on a sex (3, 4). It is tipically presented as conduction disturbances, the most common of which is the 1st degree atrioventricular (AV) block, with up to 50% of these patients progressing to complete heart block (5). Also, different forms of block can occur intermittently in a single patient (6). Complete AV block typically spontaneously (in >90% patients) resolves within one week, and more minor conduction disturbances within six weeks (7).

Diagnosis Lyme carditis can be very challenging. When AV block of unkown origin develops suddenly, Lyme carditis must be considered, especially in younger patients (6). Although erytema migrans is a very specific symptom in the acute phase, it may not be present in all cases (8). Therefore, there is a need of readily clinical testing — serologic examination, such as enzyme-linked immunosorbent assay (ELISA) (9). While awaiting the results, the electrophysiological examination should be done in patients with conduction disturbances to localize the origin of the block in order to estimate the need of implantation of a permanent or a temporary pacemaker.

A 32-year old previously healthy man was admitted for fatigue, nausea and AV block of undetected origin. On examination, the patient was conscious, afebrile and responsive with no abnormalities in physical examination except for a systolic heart murmur II/VI, punctum maximum above aortic valve. Based on the patient’s reliable account, he did not use any medications, illegal drugs and made no changes in diet which could be attributed to reported symptoms. The patient is a farmer, he is engaged in beekeeping and breeds cows and pigs. He recalls a tick bites, many of them, the last one occurred a month ago, and he noticed rash on his gluteal region, but he did not consult the family physician. There were no systemic signs of an infection or flu-like symptoms as commonly observed in the initial stage. After admission, we did routine laboratory blood testing and there were no pathological aberrations. A resting electrocardiogram showed sinus rhythm, normal length of PR interval and without other aberrations. Holter ECG revealed AV block of all grades, intermittently. Most common pathological findings was PR prolongation up to 320 ms and AV block second degree Mobitz type I. Atrioventricular block second degree Mobitz type 2 and total AV block occurred less frequently, with narrow QRS complexes and the longest RR interval of up to 3 seconds.

While waiting for serological findings for B. burgdorferi, we approached to electrophysiological examination (EPS). Results of the EPS (Figure 1): Electrophysiological study showed a spitted and prolonged His potential (35 ms), the atrio- Hisial conduction (AH interval) was normal (75 ms) and Hisventricular (HV interval) conduction was disturbed (65 ms). During the catheter stimulation from the site of the right atrium, Wenckebach appears at 660 ms. Considering the results of the electrophysiology studies, which revealed the intra- and infra-Hisian conduction disturbance, implantation of permanent double-chamber pacemaker is indicated.

Three months later, on control checkup, we verified ventricular stimulation during the 8% of the time, whereas ventricular sensing was present during the remaining time.

Lyme disease is a multisystem disease caused by Borrelia burgdorferi. Cardiac involvement with Lyme disease is extremely rare and occurs during the early disseminated phase of the disease, typically within 3-10 days of initial exposure.

Our patient, just like many other presented patients in other cases, is young, with no health problems, with the history of rash and acquired AV block of all types, so we decided to do electrophysiology study, based on suspected Lyme borreliosis. The clinical expression of Lyme disease is highly variable, but the most common cardiac manifestation is AV block (10-13).

Van der Linde, in a review of the clinical characteristics of 66 cases of Lyme carditis in Europe and 39 cases from the US, found that complete heart block was the most common form of AV block in the both groups. It was present in 49% of patients, compared to 16% with second-degree and 12% with first degree AV blocks. According to him, the risk of complete atrioventricular block is much higher when the PR interval is >300 ms (6).

Electrophysiology studies, performed in 19 patients with Lyme carditis, showed a supraventricular origin of the block in 68% of patients. One third of patients studied were believed to have had diffuse conduction system disease based upon simultaneously prolonged AA, AH and HV interval (14).

Another report suggests that 98% of the patients with AV conduction disturbances had at some time during the course of the disease the first degree AV block, while Wenckebach periodicity occurred in 40% and complete AV block in 50% (7). McAlister et al. performed an electrophysiology studies on 4 patients with Lyme disease in 1989 and 3 of them had block above the His bundle. The remaining patient who had block at or below the His bundle, required a permanent pacemaker (7).

Van der Linde also reported four cases of Lyme borreliosis induced AV block and, also, did electrophysiology studies on three of them. The studies showed that 2 of them had a suprahisal origin of the block and the third one had no terminal negative deflection of the His spike, a normal AH interval and no relation between His bundle activity and ventricular complexes (15). This shows that the site of the atrioventricular block may also lie in the distal part of the His bundle, leaving the proximal part undisturbed. In this report, despite extensive treatment with antibiotics and corticosteroid, complete AV block persisted in this patient and a permanent pacemaker had to be implanted (16, 17).

Our patient, like many other from the examples above, presented with classic conduction disturbances like intermittently recorded AV blocks of all degrees, due to Lyme borreliosis. Considering the suspected Lyme disease, what was later serological confirmed, we did the electrophysiology study. It revealed His fragmentation and its prolongation which indicates a sickness of a His. We also recorded a prolongation of HV interval which reveals a sickness of conduction structure distal of AV node (intra- and infra Hisian block). Considering to early published articles of Mc Allister and van der Linde (6, 7), we decided to implant a permanent doublechamber pacemaker. In further monitoring, the patient had no subjective complaints and at the first pacemaker operation control, as further validation of the therapeutic procedure, we verified the occasional need for ventricular stimulation (AS-VP 8%, AS-VS 92%). Based on our experience and the available literature, that is relatively older, we consider reasonable in all young people with acquired AV block with a risky profession, respectively endemic localization, EP study is to be done in one of the existing centers, in order to make a decision on the need for implantation of a permanent pacemaker or care of the patient with a temporary pacemaker during active disease (mean within 6 weeks).