Raynaud's syndrome

Effect of nitric-oxide-generating system on microcirculatory blood flow in skin of patients with severe Raynaud's syndrome: a randomised trial

BACKGROUND

Patients with Raynaud's syndrome have abnormal digital vasoconstriction, which may be secondary to impaired synthesis of, or impaired sensitivity to, nitric oxide. We studied the effect on microcirculation of a nitric-oxide-generating system applied topically to the finger and forearm of healthy volunteers and patients with primary Raynaud's syndrome.

METHODS

We did a single-blind, randomised, placebo controlled, cross-over study of the microcirculatory response to topical application of a nitric-oxidegenerating gel in 20 patients with severe Raynaud's syndrome, and ten healthy volunteers. We prepared the nitric-oxide-generating system by mixing a solution of KY jelly and sodium nitrite (5% weight/volume), with a solution of KY jelly and ascorbic acid (5% weight/volume). About 0.5 mL of each solution was separately applied to the skin of the forearm (3 cm2), and then mixed with a sterile cotton bud. A similar procedure was done simultaneously on the other arm with KY jelly only (placebo). The procedure was then repeated on the finger pulps. Changes in skin microcirculatory volume and flux were measured bilaterally by infrared photoplethysmography and laser doppler fluxmetry, respectively.

FINDINGS

In the forearm, blood flow increased significantly after application of the active gel both in patients with Raynaud's syndrome (microcirculatory volume from mean area under the curve 98 [SE 14] to 1024 [130]; microcirculatory flux from 5060 [462] to 74,800 [3940]) and in healthy controls (volume from 85 [19] to 1020 [60]; flux from 4420 [435] to 84,500 [7000]). In the fingers, although baseline blood flow was lower in patients than in controls, both groups showed increases with application of active gel (volume from 1100 [194] to 3280 [672] and 2380 [441] to 6160 [1160], respectively; flux from 33,400 [4200] to 108,000 [13,600] and 52,000 [8950] to 185,000 [19,500]). Increases in blood flow with placebo gel were not significant. No adverse effects were reported.

INTERPRETATION

In primary Raynaud's syndrome, topical application of a nitric-oxide-generating system can stimulate an increase in both microcirculatory volume and flux.

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The endothelin system and its potential as a therapeutic target in cardiovascular disease

Endothelin (ET)-1, an endothelium-derived peptide, is the most potent vasoconstrictor agent described to date. ET-1 also has positive inotropic and chronotropic effects in the heart and is a co-mitogen in both cardiac and vascular myocytes. The major elements of the system involved in formation of ET-1 and its isopeptides, as well as the receptors mediating their effects, have been cloned and characterised. Antagonists of the ET receptors are now available, and selective inhibitors of the ET-converting enzymes are being developed. Early studies using receptor antagonists support the involvement of ET-1 in the pathophysiology of several cardiovascular diseases. The relative merits of ET-converting enzyme inhibitors and receptor antagonists for the treatment of cardiovascular disease are discussed.

Vibration white finger

Vibration white finger (VWF) occurs in workers who use vibrating tools. On exposure to vibration or cold, patients experience blanching, numbness and pain in the fingers due to exaggerated vasoconstriction. This may involve both central sympathetic hyper-reactivity and local vasoactive factors. In advanced cases, hypertrophy of vascular smooth muscle causes arterial occlusion and ulceration. Diagnostic tests for VWF are unreliable. In early cases, cessation of vibration exposure arrests the progression of disease and may cause symptom remission. Patients with VWF should keep themselves warm, especially their hands, which they should place in warm water at intervals during the day; they should not smoke. Vasoactive drugs may be beneficial in some patients. In the UK, Industrial Injuries Disablement Benefit and compensation are sometimes available. Improved design of tools and restrictions on their operating time have been the main factors leading to a worldwide decline in the incidence of VWF since the early 1970s.

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A 35-year-old drug abuser inadvertently injected adulterated heroin into her left femoral artery and presented with critical ischaemia of her left leg. Treatment with intravenous Iloprost, a stable prostacyclin analogue, combined with Heparin, produced a dramatic improvement in her circulation within 4 h.

Once daily felodipine in patients with primary Raynaud's phenomenon

The symptomatic effects of felodipine (Plendil) have been assessed in 10 patients with primary Raynaud's phenomenon in a single blind study. After 2 weeks on placebo, the patients were treated for 6 weeks with felodipine, the dose being titrated stepwise every 2 weeks, starting with 5 mg, and increasing to 10 mg and 20 mg once daily if symptoms persisted. After the drug period the patients received placebo for 2 weeks. Objective measurement by cold exposure finger plethysmography did not show any benefit of felodipine in the higher temperature range, taking 33 degrees C as reference point. However, when using 24 degrees C as the reference point, the area under the plethysmography versus temperature curve (AUC) for 5 mg felodipine were significantly larger than the initial placebo area. The AUC during recovery from cold exposure for the maximal accepted dose of felodipine was significantly larger than for the initial placebo period. Subjective judgement by the patients showed a significant reduction in the number of Raynaud attacks and a trend to a shorter duration of attacks with the maximal dose of felodipine. Two patients became free from attacks of Raynaud's phenomenon. Felodipine 10 mg once daily was well tolerated. It was regarded as the optimal dose to treat patients with Raynaud's symptoms.

Reaction of capillary blood cell velocity in nailfold capillaries to nifedipine and ketanserin in patients with vasospastic disease

By using nailfold videomicroscopy in conjunction with local exposure of 60 s to cold air, the acute haemodynamic responses in capillary blood cell velocity 60 min after a single oral dose of 20 mg sustained-released nifedipine and 20 mg ketanserin were evaluated for each substance in 12 patients with vasospastic disease. The results obtained showed that the cold-induced flow stop duration was significantly (P less than 0.05) decreased and capillary blood cell velocity significantly (P less than 0.05) increased after local cooling. Systolic and diastolic blood pressure, heart rate and skin temperature did not differ significantly before and after treatment with either nifedipine or ketanserin. It is concluded that nifedipine and ketanserin are useful agents in the treatment of digital vasospastic disease. Furthermore, in vivo videomicroscopy is one of the few non-invasive and clinically useful direct methods for evaluating the effect of a drug on the microcirculation of normal and ischaemic skin areas.