Adverse psychological effects and costs associated with waiting for radiofrequency ablation.

BACKGROUND: Radiofrequency ablation (RFA) is undertaken as a potentially curative treatment for a variety of heart rhythm disturbances. Previous studies have demonstrated improved quality of life and reduced symptoms after ablation. In many health care environments waiting lists exist for scheduling of procedures. However, the psychological effects of waiting for radiofrequency ablation have not previously been assessed. We hypothesized that waiting for this intervention may be associated with increased psychological morbidity and health care costs. METHODS: Ninety-two patients scheduled for elective RFA completed repeated questionnaires comprising the Medical Outcomes Short Form 36, Hospital Anxiety and Depression Scale, and an in-house questionnaire designed to assess the burden of symptoms related to arrhythmia (arrhythmia-related burden score). Mean scores were generated and compared at time points while waiting, before and after the procedure. Regression analyses were carried out to identify predictors of increased psychological morbidity while waiting and immediately prior to the procedure. Health care costs during the waiting period as a consequence of arrhythmia were quantified. RESULTS: Mean scores for parameters of psychological morbidity worsened during the period of waiting and improved after the procedure. Predictors of adverse effects within the cohort varied according to the time point assessed for each of the measures of psychological morbidity. A conservative estimate of the health care cost incurred while waiting exceeds £ 181 per patient. CONCLUSIONS: Waiting for radiofrequency ablation appears to be associated with adverse psychological effects and health care costs. These results may support strategies to reduce waiting times and prioritize resource allocation.

Intra-arterial vasopressin in the human forearm: pharmacodynamics and the role of nitric oxide.

BACKGROUND AND OBJECTIVES: Diverse vascular effects have been ascribed to vasopressin, including the potential to cause vasodilation, vasoconstriction, and nitric oxide release. The objective of this study was to establish the pharmacodynamics, reproducibility, and nitric oxide dependence of the vasomotor actions of vasopressin in the forearm resistance vessels. METHODS: Blood flow in both forearms of 12 healthy men was measured with venous occlusion plethysmography. Continuous and discontinuous doses of 1 to 300 pmol/min vasopressin were administered by the intrabrachial route. For assessment of the contribution of nitric oxide, vasopressin was coadministered with a "nitric oxide clamp," a balanced coinfusion of 4 micromol/min L-N(G)-monomethylarginine (a nitric oxide synthase inhibitor) and 0.3 to 0.8 nmol/min sodium nitroprusside (an exogenous nitric oxide donor) to block endogenous nitric oxide production and restore normal basal blood flow, respectively. RESULTS: Vasopressin produced a dose-dependent biphasic change in blood flow with a maximum reduction in percentage change in blood flow ratio of infused and control arms of 22% +/- 5% at 3 pmol/min (P <.01) and an increase of 80% +/- 30% at 300 pmol/min (P <.01). There were no significant differences in repeated responses obtained either within or between days. Repeated discontinuous dosing did not change the magnitude of the maximum vasoconstriction or vasodilation, but prolonged continuous infusion produced maximal vasodilation at 12 minutes that subsequently resulted in substantial tachyphylaxis (P =.04). Although there was no augmentation of vasoconstriction, the nitric oxide clamp abolished vasopressin-induced vasodilation (P <.05). CONCLUSIONS: Intra-arterial vasopressin causes a reproducible dose-dependent biphasic change in forearm blood flow. Vasomotor responses are time-dependent with a modest delay to peak vasodilation and tachyphylaxis with prolonged sustained infusion. Nitric oxide release is a major contributor to vasopressin-induced vasodilation but does not directly oppose low-dose vasopressin-induced vasoconstriction.

Validation of laser Doppler flowmetry coupled with intra-dermal injection for investigating effects of vasoactive agents on the skin microcirculation in man.

OBJECTIVE: To determine the reproducibility of laser Doppler flowmetry coupled with intra-dermal saline delivery. METHODS: Delivery of saline was judged visually by two operators ( n=100), using a graduated syringe (Becton-Dickinson), by expelling saline onto a weighing boat. Volume was assessed by weight. Skin blood flow following intra-dermal injection of saline was assessed in 18 healthy volunteers; 10 attended twice to assess between-day reproducibility, and 8 attended once to assess between-site reproducibility. Results are expressed as mean value+/-SEM and 95% confidence interval for mean differences. RESULTS: There was no difference between operators in mean injection weight, both weights being 10.3+/-0.1 mg (mean difference 0.08, 95% confidence interval, CI -0.23 to 0.39 mg; n=100, P=0.9). Intra-dermal saline caused a nine-fold increase in blood flow (0.03+/-0.003 to 0.27+/-0.02 perfusion units, PU; n=18, P<0.001). This response had a rapid onset, with the maximal effect seen at 4 min and a duration of greater than 30 min. There was no difference in the magnitude of the response between the dominant and non-dominant arms, AUC was 2.9+/-0.4 and 2.9+/-0.4, respectively (mean difference -0.05, 95% CI -0.8 to 0.73 PU; n=18, P=0.93). However, there was a trend towards differences between study visits 1 and 2: AUC was 3.2+/-0.6 and 2.0+/-0.5, respectively (mean difference 1.2, 95% CI -0.03 to 2.43 PU; n=10, P=0.7). There was no difference in the magnitude of responses between different sites on the forearm ( n=64, P=0.6). CONCLUSIONS: These studies demonstrate that the technique of laser Doppler flowmetry coupled with intra-dermal injection is a safe, well-tolerated technique with good reproducibility. A trend towards reduced between-day reproducibility emphasizes the importance of vehicle control sites when investigating the effects of vasoactive compounds. This technique provides a reliable method for the intra-dermal delivery of drugs, despite the direct effect of injection of saline on blood flow.

No effect on central or peripheral blood pressure of systemic urotensin II infusion in humans.

AIMS: In rodent and primate studies, urotensin II is an extremely potent vasoconstrictor peptide with effects in the central aortic and arterial vasculature as well as on cardiac function. The aim of the present study was to assess systemic haemodynamic responses to intravenous urotensin II infusion in humans. METHODS: In 10 healthy male volunteers, intravenous urotensin II (3, 30 and 300 pmol min-1) and saline placebo were given on separate occasions in a single-blind randomized manner. Systemic haemodynamics and arterial stiffness were assessed by sphygmomanometry, transthoracic bioimpedance, and pulse wave analysis. Plasma urotensin II immuno-reactivity was measured by radio-immunoassay. RESULTS: Intravenous urotensin II infusions were well tolerated with no adverse clinical effects and no electrocardiographic changes. Circulating plasma urotensin II immuno-reactivity increased from baseline of 16 +/- 1 to 1460 +/- 82 pmol l-1 (mean +/- s.e. mean) during infusion of urotensin II at 300 pmol min-1 (P < 0.001). However, there were no significant placebo adjusted changes in heart rate (95% confidence intervals: -3.6, + 4.4 min-1), mean arterial pressure (-5.8, + 1.7 mmHg) or cardiac index (-0.1, + 0.4 l min-1 m-2). There were also no changes in augmentation index (-4.1, + 5.2%) or pulse wave velocity (-1.3, + 0.3 m s-1). CONCLUSIONS: Intravenous urotensin II infusion did not affect systemic haemodynamics or arterial stiffness, despite achieving an approximately 100-fold increase in plasma immuno-reactivity. We conclude that urotensin II is unlikely to have a physiological role in the short term regulation of vascular tone or blood pressure in man. Further confirmatory studies with urotensin II receptor antagonists are required.

High plasma concentrations of human urotensin II do not alter local or systemic hemodynamics in man.

OBJECTIVE: Human urotensin II (hUII) is an endocrine hormone that acts as a potent arterial vasoconstrictor in both in vitro and in vivo studies in animals. We examined, for the first time, the local and systemic hemodynamic response to hUII in man in vivo. METHODS: Four healthy male volunteers took part in pilot studies and 11 in definitive studies. Forearm blood flow (FBF) was measured in response to intra-arterial infusion of authentic, biologically active hUII (incremental rates of 0.001-300 pmol min(-1)) and saline placebo using venous occlusion plethysmography. Blood pressure, heart rate, cardiac output and hUII plasma concentrations were also measured. Forearm studies were repeated in five subjects with inhibition of endothelial mediators using aspirin and a "nitric oxide clamp". Dorsal hand vein diameter was determined by a standard displacement technique in response to local administration of hUII (3-300 pmol min(-1)) with and without nitric oxide synthase inhibition. RESULTS: There was no significant change in FBF during brachial infusion of saline or hUII (dose range, 0.001 to 300 pmol min(-1)). A nitric oxide clamp did not unmask vasoactive effects of hUII. Human UII infusions (100 and 300 pmol min(-1)) significantly increased plasma hUII concentrations from baseline (12 +/- 3 pmol l(-1)) to 106 +/- 15 and 307 +/- 98 pmol l(-1), respectively. Despite high circulating hUII concentrations, no change was seen in systemic hemodynamics and ECGs were unchanged. Human UII had no effect on hand vein diameter (n=6). CONCLUSIONS: In contrast to our hypothesised role of hUII, we found no vasoactive responses to hUII in vivo, consistent with recent in vitro studies in human blood vessels, but in contrast to non-human primate studies in vivo. Our data do not support a key role for hUII in the regulation of vascular tone and resting blood pressure in man. However, studies with hUII receptor antagonists are also needed before firm conclusions can be drawn.