|Carnitine and Cardiovascular Diseases|
This book has been primarily written for scientifically minded physicians, who are interested in obtaining, for the benefit of their patients, a deeper insight into the interesting topic of the application of L-carnitine and its esters acetyl-L-carnitine and propionyl-L-carnitine in the field of cardiovascular diseases.
Over the last decades, recognition of the medical significance of
L-carnitine has increased continuously - a fact which is also con-firmed by the growing number of publications. At the end of the year 2002, 7564 medical publications on this compound were registered on the INTERNET, and this figure does not even include publications on its physical and chemical aspects. Moreover, as the INTERNET only includes papers published in 1963 or later, a significant number of publications is not mentioned there.
Of these 7564 medical publications, 1555 (or 21 %) focus on cardiovascular problems.
Because of the enormous number of publications describing the effects of L-carnitine and its esters on the heart, the papers discussed in this book can be nothing more than a selection that is far from complete. Although the author has attempted to include at least the most important papers, it may well be that he has not always been successful in this task. However, a more comprehensive discussion of the respective literature would have made the book much too unwieldy for its intended circle of readers.
One possible way of overcoming this problem would have been to include only the latest literature, e.g. to concentrate only on the last ten years. In our opinion, however, such an approach would have done unacceptable injustice to those colleagues who, even though their papers may be somewhat older, have pioneered in establishing the fundamental metabolic effects of carnitine. It is simply impossible to write about carnitine without mentioning the work of pioneers such as J Bremer, PK Bhattacharyya, HR Carter, G Fraenkel, S Friedman, IB Fritz, G und S Lindstedt, E Strack and other trailblazers of early carnitine research. Therefore, the author has decided against using only the latest literature.
With such a large number of publications, misunderstandings or mistakes are probably unavoidable, but the author would nevertheless like to apologise in advance for any such case. At the same time he would like to ask his esteemed colleagues and readers to inform him of any incorrect information or points that may need clarification, so that they can be corrected in a later edition.
The importance of such an overview is mainly due to the fact that a large number of physicians is obviously not too familiar with the effects of L-carnitine although, as mentioned above, the number of scientific publications has grown to hardly surveyable dimensions. In spite of the fact that carnitine was discovered nearly 100 years ago, its fundamental metabolic effects have only recently become a topic in the training of medical students. For practising physicians, who have only a very limited amount of time at their disposal, it is nearly impossible to follow all developments published in the medical scientific literature. In addition, catchpenny articles in the so-called „yellow press“ have vastly damaged the reputation of carnitine: Its effects were either exaggerated (e.g. „Carnitine - the slimming wonder“), or it was credited with effects it does not have. Therefore, some colleagues may see carnitine as some kind of „designer drug“ or voice the opinion that its effects have been exaggerated „to produce huge profits for the pharmaceutical industry“. One reason for publishing this book is the intention to rectify misinterpretations of the effects of L-carnitine and to inform about its therapeutic applications, which have been studied in our institute since 1935.
As the following chapters will show, beneficial effects of L-carnitine on cardiovascular diseases were found in the vast majority of cases, but this book also discusses publications which reported only weak effects of L-carnitine or even none at all. The influence of L-carnitine and its esters on cardiovascular processes is not seen in the same positive way by all authors. The cardio-protective effects of L-carnitine appeared to be undisputed for years, but now several researchers attribute these effects less to L-carnitine than to propionyl-L-carnitine. In most cases, however, therapeutic failure can be attributed to a too low dosage, a too short duration of treatment, or to an excessive influence of concomitant medication.
Many authors have found positive effects of L-carnitine appli-cation in ischemia and stable angina pectoris: Exercise heart rate, pressure rate product, ST-segment depression and consumption of nitrates were decreased, and the exercise time to the onset of angina pectoris was increased. L-carnitine treatment of patients suffering from acute myocardial infarction reduced ventricular extrasystoles, ventricular tachycardia and the size of the necrotic area. In patients suffering from cardiac arrhythmias, L-carnitine reduced ventricular extrasystoles during exercise. Patients suffering from cardio-myopathies showed an improved ejection fraction as well as clinical improvement of heart function after application of L-carnitine.
With diphtheritic patients, L-carnitine reduced the number of heart failures, pacemaker implantations and lethal myocarditises. Patients with chronic hemodialysis experienced a lower incidence of arrhythmias and fewer angina pectoris complaints. L-carnitine application in patients with cardiac failure effected clinical improvement by reducing digitalis doses, dyspnoea and nitrate consumption, it also lowered the number of oedemas and angina incidents and effected an increase in diuresis. In cases of septic, cardiogenic and intraoperative shock, acetyl-L-carnitine increased systolic blood pressure and diuresis. Patients suffering from vasculopathies had fewer trophic lesions and were able to walk longer distances free of pain as well as longer distances in general after carnitine or propionyl-L-carnitine administration.
Because of the positive effects of L-carnitine, an adjuvant therapy with L-carnitine should be considered for the clinical pictures mentioned above.
I would like to use this opportunity to express my sincere thanks to my publisher, Ponte Press Verlags GmbH, and to Dr. J. Bücheler in particular, for the friendly support given to this manuscript and for accepting all the modifications asked for by the author.
I would also like to extend my thanks to my translator, Diplom-Sprachmittler P. Schwär, for his longstanding and congenial support in the preparation of the English version of this difficult text.
Leipzig 2003, Heinz Löster