Lev's disease, also known as Lenègre disease, is an idiopathic disease that can result in a complete heart block, or an extremely slowed heart rate, in patients with this condition. It is thought that for certain patients, this impairment of heart's electrical conduction system is due to fibrosis and calcification of conduction cells. This disease is considered to be age related, with increasing decline seen in elderly patients. The use of electrocardiograms, especially in non-specialized settings like emergency rooms, may incidentally reveal a dysrhythmia that can confuse diagnosis, however serial ECGs will demonstrate an evolving conduction block arrhythmia characteristic of Lev's disease, thus allowing for correct diagnosis.
Presentation
Signs and symptoms Lev's disease may present with various signs and symptoms; however, these may overlap with similar conditions such as atrioventricular (AV) blocks. Symptoms of Lev's disease may include syncope, shortness of breath, dizziness, heart failure, and sudden cardiac death. Symptoms may begin to appear as an adult. On the other hand, signs of Lev's disease may include bradycardia, defects in the cardiac conduction of the His-Purkinje system, widening of the QRS complex, and temporal potentially prolongation of the PR interval. However, individuals may also be asymptomatic, presenting with no symptoms. Thus, careful genetic screening and identification of patients with Lev's disease is important.
Associated conditions Stokes–Adams attacks can be precipitated by this condition. These involve a temporary loss of consciousness resulting from marked slowing of the heart when the atrial impulse is no longer conducted to the ventricles. This should not be confused with the catastrophic loss of heartbeat seen with ventricular fibrillation or asystole. Atrioventricular (AV) block may be a progression of Lev's disease, in which the electrical signal transmission from the heart's atria to the ventricles is impaired due to an extension of the fibrosis. Bundle Branch Block (BBB) is another condition that can be precipitated by Lev's disease. This condition is the interrupted conduction of electrical impulses along the Bundle of His or one of the bundle branches. As the Bundle of His divides into the right and left bundle branches, a block of the electrical impulse may result in a Right Bundle Branch Block or a Left Bundle Branch Block, respectively. Sinoatrial (SA) block may also result be a result of Lev's disease. During a SA block, the electrical impulse formed at the SA node is delayed or not conducted.
History In March 1954, researchers Richman and Wolff analyzed several patient cases using electrocardiograms and vectorcardiograms. In terms of the different cardiovascular diagnostic tests available, electrocardiograms are the most widely used between physicians. Many providers prefer the use of electrocardiograms since the process of interpreting vectorcardiograms are more complex and are more labor-intensive as it requires more electrode placement on patients. Electrocardiograms record and detect the electrical impulses generated by the heart. By doing so, medical professionals are able to analyze the electrical activity of the heart and detect any irregularities that may impact the function of the heart. However, vectorcardiogram diagnostic tests operate differently from electrocardiograms. This vectorcardiogram method analyzes the transverse, sagittal, and frontal planes to measure the electrical activity of the heart. This diagnostic test examines different factors such as rotations, contours, and the direction of the cardiac axis of the heart. Although the use of electrocardiograms are commonly used in clinical settings by many providers, vectorcardiograms are able to be more precise due to its ability to detect and identify the location of myocardial infarction, cardiac blockage, and hypertrophy. Among cases studied, patients exhibited a left bundle branch block that resembled a right bundle branch block. In comparison, however, although the electrocardiograms showed a right bundle branch block, the vectorcardiograms detected a left bundle branch block in the patient. In March 1964, Jean Lenègre published a paper discussing the pathology behind the gradual damage and scarring of the ventricular conduction system. In November 1964, Maurice Lev published a paper with similar findings as Lenègre where he saw the degenerative processes of the ventricular conduction system associated with calcification in older patient populations. Lev focused primarily on the anatomical process leading to atrioventricular blocks in patients and was able to build off the research conducted by Lenègre.
Epidemiology In a genetic epidemiological study published in 2012 focusing on western France, there were 6667 patients implanted with pacemakers for PCCD between the years of 1995 and 2005. The frequency of PCCD in different areas of western France was concluded to be 0.21% in a major city and up to 2.28% in specific parishes. Five large families were also identified to be affected by PCCD, contributing to the understanding that the disease has a genetic factor. While there is limited data directly addressing Lev's disease and its prevalence, there are also some statistics on the associated diseases precipitated by Lev's disease. One study published in 1998 followed 855 men born in 1913, and among the group the prevalence of bundle branch block was 17% when the study population was at age 80 years.
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