Atrial assist device, a new alternative to lifelong anticoagulation?

OBJECTIVE: Atrial fibrillation is a very common heart arrhythmia, associated with a five-fold increase in the risk of embolic strokes. Treatment strategies encompass palliative drugs or surgical procedures all of which can restore sinus rhythm. Unfortunately, atria often fail to recover their mechanical function and patients therefore require lifelong anticoagulation therapy. A motorless volume displacing device (Atripump) based on artificial muscle technology, positioned on the external surface of atrium could avoid the need of oral anticoagulation and its haemorrhagic complications. An animal study was conducted in order to assess the haemodynamic effects that such a pump could provide. METHODS: Atripump is a dome-shape siliconecoated nitinol actuator sewn on the external surface of the atrium. It is driven by a pacemaker-like control unit. Five non-anticoagulated sheep were selected for this experiment. The right atrium was surgically exposed, the device sutured and connected. Haemodynamic parameters and intracardiac ultrasound (ICUS) data were recorded in each animal and under three conditions; baseline; atrial fibrillation (AF); atripump assisted AF (aaAF). RESULTS: In two animals, after 20 min of AF, small thrombi appeared in the right atrial appendix and were washed out once the pump was turned on. Assistance also enhanced atrial ejection fraction. 31% baseline; 5% during AF; 20% under aaAF. Right atrial systolic surfaces (cm2) were; 5.2 +/- 0.3 baseline; 6.2 +/- 0.1 AF; 5.4 +/- 0.3 aaAF. CONCLUSION: This compact and reliable pump seems to restore the atrial "kick" and prevents embolic events. It could avoid long-term anticoagulation therapy and open new hopes in the care of end-stage heart failure.

Premedication with antihistamines may enhance efficacy of specific-allergen immunotherapy.

BACKGROUND: Antihistamine premedication has been used to increase safety of specific-allergen immunotherapy. Its influence on the efficacy of this treatment has not been studied so far. OBJECTIVE: The goal was to analyze the influence of antihistamine premedication on long-term efficacy of specific-allergen immunotherapy. METHOD: Patients included in a double-blind, placebo controlled trial who received premedication with terfenadine or placebo during initial rush immunotherapy with honeybee venom in 1988/1989 were assessed in a retrospective analysis for the long-term protective effect, as indicated by the tolerance of a bee sting challenge or field sting during immunotherapy. RESULTS: Of the 52 patients who had participated in the 1988/1989 trial, 47 could be reassessed after an average of 3 years. Of these, 45 were still receiving bee venom immunotherapy. A total of 41 patients were stung by bees while receiving immunotherapy (20 of the terfenadine-premedicated group and 21 of the placebo-premedicated group), 17 with in-field stings and 24 with in-hospital sting challenge. Six (29%) of the patients receiving placebo had a mild-to-moderate systemic allergic reaction, whereas none of the patients receiving terfenadine reacted to the bee sting (P =.012). CONCLUSIONS: These results indicate that antihistamine premedication during the initial phase of specific-allergen immunotherapy may enhance the efficacy of this treatment.

Allergy to honey: relation to pollen and honey bee allergy.

To identify the allergenic components of honey we studied 22 patients with a history of systemic allergic symptoms following honey ingestion. The group of honey-allergic patients was compared with three control groups: 10 subjects sensitized to artemisia, 10 with honey bee venom allergy and 10 without a history of atopy or bee sting reactions. The allergological tests included skin tests and RAST with three different kinds of Swiss honey (dandelion, forest and rape), pollen of compositae species, celery tuber, extract of bee pharyngeal glands, honey bee venom and bee whole body extract. The results show that 3/4 of honey-allergics are sensitive to dandelion honey and 13 of 22 also to compositae pollen. Nine of the honey allergic patients were sensitized to honey bee venom, 3 also to bee pharyngeal glands and to bee whole body extract. Analysis of diagnostic tests and RAST inhibition studies suggest that besides compositae pollen other allergens, most likely of bee origin are important. In honey allergics primary sensitization may be due either to the honey itself, to airborne compositae pollen or even to cross-reacting bee venom components.

Immunotherapy with honeybee venom and yellow jacket venom is different regarding efficacy and safety.

Venom immunotherapy (VIT) for Hymenoptera allergy is accepted as safe and effective. However, widely varying success rates and frequencies of side effects are reported. Differences between various Hymenoptera species could account for these diverging results. We therefore analyzed 205 patients with a history of systemic allergic reactions to either honeybee (148 patients) or yellow jacket stings (57 patients) during VIT. All patients had a positive skin test to the respective venom before VIT, were monitored for side effects of VIT, and submitted to a sting challenge while they were receiving VIT. Patients with honeybee-venom allergy had a higher sensitivity in both skin tests (p less than 0.05) and RAST (p less than 0.001) than patients with yellow jacket-venom allergy. They developed systemic side effects to VIT injections significantly more often (41% versus 25%; p less than 0.01) and also reacted more frequently to the sting challenge (23% versus 9%; p less than 0.01) than patients with yellow jacket-venom allergy. We conclude that results obtained from studies on the allergy to one Hymenoptera venom cannot be extrapolated to allergies to other Hymenoptera venoms.

Reduction of side effects from rush-immunotherapy with honey bee venom by pretreatment with terfenadine.

In a double-blind placebo-controlled trial on 52 patients with bee venom allergy we studied the effect of a pretreatment with terfenadine 120 mg twice daily on the occurrence of local and systemic allergic side effects from rush-immunotherapy. Large local reactions were significantly reduced by terfenadine pretreatment (P less than 0.01), while systemic side effects were observed with similar frequencies in both groups. Analysis of individual systemic allergic manifestations showed that cutaneous symptoms like itching (P less than 0.025) and urticaria/angioedema (P less than 0.05) were significantly reduced, while respiratory or cardiovascular symptoms were not influenced. A lower consumption of additional anti-allergic medication was found during terfenadine pretreatment (P less than 0.05). Pretreatment with antihistamines during immunotherapy may thus be helpful in the management of patients with cutaneous side effects.

Honeybee venom allergy: results of a sting challenge 1 year after stopping successful venom immunotherapy in 86 patients.

In 86 patients with a history of severe systemic reactions (SRs) to honeybee stings confirmed by a positive skin test and/or RAST to honeybee venom (HBV), immunotherapy (IT) with HBV was stopped after 3 to 10 years. All patients had tolerated well a honeybee sting during IT and were resubmitted to a sting 1 year after VIT was stopped. At the latter time, 15 patients (17%) developed an SR and 71 did not. There was no difference between the two groups regarding age, sex, IT duration, severity of the SR before treatment, as well as diagnostic tests with HBV (skin tests, RAST, and specific IgG) before the challenge. Patients with a relapse of their allergy had, however, developed allergic SRs to IT injections more frequently than patients with lasting protection (p less than 0.001). SRs to the sting challenge (CH) after IT was stopped occurred more frequently in those patients in whom efficacy of IT had previously been confirmed by lacking responses to a field sting than in patients who had tolerated an intentional CH during the injection period (p less than 0.025). Indeed, the incidence of relapse after venom IT was stopped was only 9.6% in patients who had previously tolerated an intentional CH. It is concluded that well-tolerated HBV IT may be stopped after at least 3 years, provided its efficacy has been documented by a CH without SR.