Low level laser therapy (LLLT) has been investigated and used clinically for over 30 years, mostly in Eastern Europe and Asia. The ability of lasers to cut, cauterise, and destroy tissue is well known throughout the medical world. However, its role at lower power is less well appreciated. The ability to non-thermally and non-destructively change cell function is known as laser biostimulation and is the basis for the current use of lasers in a number of medical fields. The worldwide interest in LLLT is illustrated by its use in more than 85 institutions in over 37 countries. Since the first study was reported in 1967, some 2500 papers have been published in a range of journals worldwide and the value of LLLT is much better reported than many believe. Its scientific background is sound enough to say that it is both safe and effective. However, positive double blind studies are unfortunately none too easy to find. Among the 100 selected for evaluation in this review, only 28 could be found on Medline. Many studies have been published in regional or national publications, which are not indexed on Medline or similar databases. The main reasons for this restricted publication include language barriers and lack of availability of professional journals because of financial constraints. Table 1 gives a summary of published studies of low intensity laser therapy for cardiovascular disease.

Most reports are in Russian and the basis for clinical research and practice was first established in Moscow in 1986. The Institute of Laser Medicine was formed through a union of 14 laser centres from different parts of Russia. LLLT emerged as a potential therapeutic modality because of the conversion of military production into areas of commercial practice including medicine. The largest complex of laser research was founded in the closed city of Kaluga and in 1995 this was opened by order of the Russian government. As a result clinicians in Russia and Ukraine now have access to a wide variety of invasive and non-invasive lasers and there are numerous specialised laser centres throughout these countries. A wide range of laser applications have been used to treat large numbers of patients and in recent times up to 1.5 million patients have been treated annually.

The reasons behind the widespread application of LLLT in Russia and Ukraine are evident. Today medicine is dominated by expensive pharmaceuticals and advanced technologies. The ever-growing emergence of resistant bacteria and patient sensitivity to drugs should encourage a search for new therapeutic modalities. Laser irradiation shows particular hope in this area with virtually no contraindications, and limited side effects. However, there are some contraindications to the use of LLLT and these include:

• malignant tumours located in an irradiated area

• epilepsy

• use over the thyroid gland

• irradiation of the abdomen during pregnancy

• light hypersensitivity

• thrombosis in a pelvic vein or a deep vein of the legs.

Today much more is known about the effects of laser light on biochemical and cellular function than was the case 20 years ago and the following benefits have been suggested:

1. cellular metabolic activation and increased functional activity (ATP synthesis is increased by up to 150%)¹

2. stimulation of repair processes as a result of increased cell proliferation^2–4

3. anti-inflammatory effects^1,2

4. microcirculation activation and more efficient tissue metabolism^1,5–7

5. analgesic effects as a result of increased endorphin release^8,9,10,11

6. immunostimulation with correction of cellular and humoral immunity¹

7. increased antioxidant activity in the blood^9,12,13

8. stabilising lipid peroxidation in cell membranes^5,6,14

9. stimulation of erythropoiesis^1,13,15

10. vasodilatation^3,6,12

11. normalisation of acid base balance in the blood^2,12,16

12. reflexogenic effects on the functional activity of different organs and systems^17,18 (fig 1)

There are indications that LLLT also has a role:

• during periods of recovery after trauma or surgery

• in treatment of hyperlipidaemia when diet and pharmacological interventions have been ineffective

• in strengthening the immune response.

In addition, Ohshiro and Calderhead¹⁹ believe low intensity laser irradiation may work through effects on the central nervous system. They have suggested this occurs through tissue photobioactivation, in which the energy levels of biological structures are changed through light quantum absorption. Human tissue absorbs light energy and this stimulates and modifies metabolic processes. It results in reorganisation of protein polymers. In particular, it changes the structural and functional properties of cell membranes as well as fermentation processes. In this way it has some similarities to the action of sunlight in plant photosynthesis.

From more than 10 years practical experience with low intensity laser irradiation in cardiology in Ukraine, it is clear that it offers new treatment possibilities. These include improved rheological characteristics of the blood and microcirculation as well as normalisation of hormonal and immune parameters.^4,13,16,17 In particular LLLT can be part of a range of therapeutic modalities for patients with ischaemic heart disease, where it can reduce the risk of acute myocardial infarction. Over a period of 10 years one of the authors (TM) studied about 500 outpatients with this condition and 60% had laser treatment on two or more occasions. Some 70% of patients experienced a positive clinical benefit.

Methodologically there are two basic techniques—intravenous laser blood irradiation (ILBI) by HeNe laser in the red spectrum and a simultaneous percutaneous low laser irradiation by laser in the infrared spectrum on to projections of reflexogenic and acupuncture areas. From practical experience TM believe this is the best combination for treatment, but it awaits confirmation in a double blind trial.

Intravenous laser blood irradiation was developed experimentally by the Russian researchers, Meshalkin and Sergievskiy,²⁰ and introduced into clinical practice in 1981. Originally the method was applied in the treatment of cardiovascular abnormalities.

Now, the first approach that is generally used in this situation is HeNe laser (632.8 nm) via an intravenous catheter for irradiation of the blood. The usual parameters are: output at the end of the light guide inserted into a vein from 1 mW to 4 mW with an exposure 10–60 minutes. Procedures are conducted on a daily basis or every other day, for between 3 and 10 sessions. The second therapeutic approach is through skin contact using a wavelength (830 nm), and output 40 mW, frequency 5 Hz. Infrared laser irradiation of the skin is directed at the heart projection and Zaharyan’s-Head’s zones (fig 2). Procedures are conducted on a daily basis or on alternate days for 6 to 10 sessions. Photoactivation of the reflexogenic areas by infrared spectrum laser stimulates nervous and humoral regulatory mechanisms. This method is used in both treatment and prevention of coronary heart disease, cardiac arrhythmias,^17,18,21 diabetes mellitus,⁵ hypertension, and occlusive vascular diseases.³

Intravenous HeNe laser blood irradiation (IV HeNe LBI) has a wide range of actions, which include biostimulation, analgesia, antiallergic effects, immunomodulation, vasodilatation, antiarrhythmic,^4,18,22 antihypoxic, spasmolytic, and anti-inflammatory effects. In addition IV LBI procedures on patients with ischaemic heart disease can be helpful when there is resistance to nitrates,^2,16,17 β blocking drugs, and calcium channel blockers.^18,22 Reported effects include reduced need for nitroglycerine tablets, decreased number of angina episodes, alleviation of pain, suppression of lipid peroxidation, increased antioxidant protection of erythrocyte membranes, reduction of fibrinogen levels, normalisation of antithrombin-III, reduced activity of the pituitary-adrenal axis, and aldosterone-renin-angiotensin system.^23,24

IV LBI improves the rheological properties of blood, increasing its fluidity and activating transport functions. This is accompanied by increased oxygen levels, as well as decreased carbon dioxide partial pressures. The arteriovenous difference for oxygen is increased, which confirms a reduction in tissue hypoxia with a return to normal metabolism. Probably, the basis for activation of oxygen transport by IV LBL is through an effect on haemoglobin. The augmentation of oxygen levels improves tissues metabolism. In addition, laser irradiation activates ATP synthesis and energy formation in cells.²⁴ The application of IV LBI in cardiology has shown that the procedure has analgesic effects, which increase exercise tolerance for patients and prolong periods of remission. The mechanism might be through reduced platelet aggregation and activation of fibrinolysis and so increased peripheral blood flow and tissue oxygenation. The improvement seen in the microcirculation is also attributable to vasodilatation and changes in the physicochemical properties of erythrocytes. In particular there is a rise in their negative electric charge. In addition there is unblocking of capillaries and collaterals as well as normalisation of the nervous excitability of smooth muscle in vascular walls.¹⁶

The individualisation of doses of IV LBI is an important factor in guaranteeing successful treatment. This technique has solved the problem of “secondary aggravation” of disease during laser therapy. This phenomenon depends upon the initial exposure and output power of the irradiation. The initial dose should be minimal during the first procedure and then increased gradually up to the fifth procedure. For patients under 60 years old with coronary heart disease an output power at the end of the venous light guide should be from 2 mW to 4 mW, with an initial exposure of the blood for seven to eight minutes as the standard approach. There are subsequent increases in the exposure time of up to 15 minutes during the fifth procedure. For patients over 60 years the exposure is reduced. The usual parameters of blood irradiation for this group of patients are output power at the end of the venous light guide from 1 mW to 3 mW, with an exposure from five minutes on the first procedure up to 10 minutes during the fifth procedure.

This simple method for individualisation of the course of laser therapy is based on observing the phenomenon of “scarlet blood”. This is seen when placing intravenous cannulas with their light guide into a vein. The appearance of this phenomenon during the third to fifth procedures of intravenous LBL coincides with the production of nitric oxide. Nitric oxide is an endothelial relaxation factor involved in the circulation of blood, immune function, communications between nerve cells, as well as rheological characteristics of the blood and coronary microcirculation. Nitric oxide plays a key part in the maintenance of vasodilatation and decreases high blood pressure. However, surplus nitric oxide is harmful and can cause oxidative damage. It is possible to limit these harmful effects by use of antioxidants, such as a complex of two vitamins A and E, (AEVIT).¹⁷ This “arterialisation” of patients’ blood means that the procedure should be suspended or carried out less frequently (every two to three days rather than daily). Sometimes symptoms of hypercoagulation are coincident with the appearance of “scarlet blood” and this can limit clinical efficacy.

The biological effect of laser light on various conditions is complex and more research is needed to find the optimal parameters for treatment. Scientific research and clinical experiments on LLLT will help confirm whether it has a definite role in the treatment and prophylaxis of ischaemic cardiac disease. While some may regard LLLT as a magical electrotherapeutic panacea, and others consider it useless, there is a current need for clinical investigators to research these new laser medical devices. Additional research is needed to obtain data concerning success rates in treating specific conditions. This should include length of exposure, frequency of treatments, and related therapeutic protocols. The studies must conform to rigorous standards and clearly there is a place for double blind randomised control trials. It is only with robust data from such exacting studies that LLLT will come to be accepted as an effective modality of treatment. However, the clinical experience described in this paper should be a prompt to manufacturers of LLLT equipment to fund such work.