Cardiovascular changes after administration of aerosolized salbutamol in horses: five cases

Prevention and treatment of intraoperative hypoxemia in horses is difficult and both efficacy and safety of therapeutic maneuvers have to be taken into account. Inhaled salbutamol has been suggested as treatment of hypoxia in horses during general anesthesia, due to safety and ease of the technique. The present report describes the occurrence of clinically relevant unwanted cardiovascular effects (i.e. tachycardia and blood pressure modifications) in 5 horses undergoing general anesthesia in dorsal recumbency after salbutamol inhalation. Balanced anesthesia based on inhalation of isoflurane in oxygen or oxygen and air and continuous rate infusion (CRI) of lidocaine, romifidine, or combination of lidocaine and guaifenesine and ketamine was provided. Supportive measures were necessary to restore normal cardiovascular function in all horses but no long-term adverse effects were noticed in any of the cases

Pearls and perils of an implantable defibrillator trial using a common control: implications for the design of future studies

Abstract Aims Implantable defibrillators are considered life-saving therapy in heart failure (CHF) patients. Surprisingly, the recent Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT) reached an opposing conclusion from that of numerous other trials about their survival benefit in patients with advanced CHF. A critical analysis of common control trial design may explain this paradoxical finding, with important implications for future studies. Methods and Results Common control trials compare several intervention groups to a single rather than separate control groups. Though potentially requiring fewer patients than trials using separate controls, variation in the common control group will influence all comparisons and creates correlations between findings. During subgroup analyses, this dependency of outcomes may increase belief in the presence of a real subgroup effect when, in fact, it should increase skepticism. For example, a high (r = 0.92), statistically unlikely (p = 0.052) correlation between comparisons was observed across the subgroups reported in SCD-HeFT. Such concordance between amiodarone and a defibrillator across subgroups was unexpected, given how much the effects of these treatments significantly differed from one another in the main study. This suggests the study's subgroup findings (specifically the absence of benefit from defibrillators in advanced CHF) were not necessarily a consequence of treatment; more likely, they resulted from variation in what the treatments were compared against, the common control. Conclusion Common control trials can be more efficient than other designs, but induce dependence between treatment comparisons and require cautious interpretation.</p

Multiple interactions between the alpha2C- and beta1-adrenergic receptors influence heart failure survival

<p>Abstract</p> <p>Background</p> <p>Persistent stimulation of cardiac β₁-adrenergic receptors by endogenous norepinephrine promotes heart failure progression. Polymorphisms of this gene are known to alter receptor function or expression, as are polymorphisms of the α_2C-adrenergic receptor, which regulates norepinephrine release from cardiac presynaptic nerves. The purpose of this study was to investigate possible synergistic effects of polymorphisms of these two intronless genes (<it>ADRB1 </it>and <it>ADRA2C</it>, respectively) on the risk of death/transplant in heart failure patients.</p> <p>Methods</p> <p>Sixteen sequence variations in <it>ADRA2C </it>and 17 sequence variations in <it>ADRB1 </it>were genotyped in a longitudinal study of 655 white heart failure patients. Eleven sequence variations in each gene were polymorphic in the heart failure cohort. Cox proportional hazards modeling was used to identify polymorphisms and potential intra- or intergenic interactions that influenced risk of death or cardiac transplant. A leave-one-out cross-validation method was utilized for internal validation.</p> <p>Results</p> <p>Three polymorphisms in <it>ADRA2C </it>and five polymorphisms in <it>ADRB1 </it>were involved in eight cross-validated epistatic interactions identifying several two-locus genotype classes with significant relative risks ranging from 3.02 to 9.23. There was no evidence of intragenic epistasis. Combining high risk genotype classes across epistatic pairs to take into account linkage disequilibrium, the relative risk of death or transplant was 3.35 (1.82, 6.18) relative to all other genotype classes.</p> <p>Conclusion</p> <p>Multiple polymorphisms act synergistically between the <it>ADRA2C </it>and <it>ADRB1 </it>genes to increase risk of death or cardiac transplant in heart failure patients.</p

The fusion band in V1: a simple ECG guide to optimal resynchronization? An echocardiographic case report

BACKGROUND: Patients with left bundle branch block have a preserved right bundle branch conduction and the efficacy of left ventricular pacing could be explained with the fusion between artificial pulse delivered in the left lateral wall and the spontaneous right ventricular activation. Moreover, the efficacy of left ventricular pacing could be enhanced with an optimal timing between the spontaneous right ventricular activation and the left ventricular pulse. CASE PRESENTATION: We evaluated a patient (male, 47 yrs) with surgically corrected mitral regurgitation, sinus rhythm and left bundle branch block, heart failure (NYHA class III) despite medical therapy and low ejection fraction (25%): he was implanted with a biventricular device. We programmed ventricular pacing only through the left ventricular lead. We defined what we called electrocardiographic "fusion band" as follow: programming OFF the stimulator, we recorded the native electrocardiogram and measured, through the device, the intrinsic atrioventricular interval. Then, atrioventricular interval was progressively shortened by steps of 20 ms down to 100 ms. Twelve leads electrocardiogram was recorded at each step. The fusion band is the range of AV intervals at which surface electrocardiogram (mainly in V1 lead) presents an intermediate morphology between the native left bundle branch block (upper limit of the band) and the fully paced right bundle branch block (lower limit). The patient underwent echocardiographic examination at each atrioventricular interval chosen inside the fusion band. The following parameters were evaluated: ejection fraction, diastolic filling time, E wave deceleration time, aortic velocity time integral and myocardial performance index. All the echocardiographic parameters showed an improvement inside the fusion band, with a "plateau" behaviour. As the fusion band in this patient ranged from an atrioventricular delay of 200 ms to an atrioventricular delay of 120 ms, we chose an intermediate atrioventricular delay of 160 ms, presuming that this might guarantee the persistence of fusion even during any possible physiological (autonomic, effort) atrioventricular conduction variation. CONCLUSION: In this heart failure patient with left bundle branch block, tailoring of the atrioventricular interval resynchronized myocardial contraction with left ventricular pacing alone, utilizing a sensed right atrial activity and the surface electrocardiographic pattern

Effective cardiac resynchronization therapy for an adolescent patient with dilated cardiomyopathy seven years after mitral valve replacement and septal anterior ventricular exclusion

Cardiac resynchronization therapy (CRT) is a new treatment for refractory heart failure. However, most heart failure patients treated with CRT are middle-aged or old patients with idiopathic or ischemic dilated cardiomyopathy. We treated a 17 year 11 month old girl with dilated cardiomyopathy after mitral valve replacement (MVR) and septal anterior ventricular exclusion (SAVE). Seven years after the SAVE procedure, she presented complaining of palpitations and general fatigue with normal activity. Her echocardiogram showed reduced left ventricular function. Despite of optimal medical therapy, her left ventricular function continued to decline and she experienced regular arrhythmias such as premature ventricular contractions. We thus elected to perform cardiac resynchronization therapy with defibrillator (CRT-D). After CRT-D, her clinical symptoms improved dramatically and left ventricular ejection fraction (LVEF) improved from 31.2% to 51.3% as assessed by echocardiogram. Serum BNP levels decreased from 448.2 to 213.6 pg/ml. On ECG, arrhythmias were remarkably reduced and QRS duration was shortened from 174 to 152 msec. In conclusion, CRT-D is an effective therapeutic option for adolescent patients with refractory heart failure after left ventricular volume reduction surgery

Successful reduction of intraventricular asynchrony is associated with superior response to cardiac resynchronization therapy

<p>Abstract</p> <p>Background</p> <p>Cardiac resynchronization therapy (CRT) is generally associated with a low to moderate increase of the left ventricular ejection fraction (LVEF). In some patients, however, LVEF improves remarkably and reaches near-normal values. The aim of the present study was to further characterize these so called 'super-responders' with a special focus on the extent of intra- and interventricular asynchrony before and after device implantation compared to average responders.</p> <p>Methods</p> <p>37 consecutive patients who underwent CRT device implantation according to current guidelines were included in the study. Patients were examined by echocardiography before, one day after and six months after device implantation. Pre-defined criterion for superior response to CRT was an LVEF increase > 15% after six months.</p> <p>Results</p> <p>At follow-up, eight patients (21.6%) were identified as super-responders. There were no significant differences regarding age, gender, prevalence of ischemic heart disease and LVEF between average and super-responders at baseline. After six months, LVEF had significantly increased from 26.7% ± 5.7% to 33.1% ± 7.9% (<it>p </it>< 0.001) in average and from 24.0% ± 6.7% to 50.3% ± 7.4% (<it>p </it>< 0.001) in super-responders. Both groups showed a significant reduction of QRS duration as well as LV end-diastolic and -systolic volumes under CRT. At baseline, the interventricular mechanical delay (IVMD) was 53.7 ± 20.9 ms in average and 56.9 ± 22.4 ms in super-responders - representing a similar extent of interventricular asynchrony in both groups (<it>p </it>= 0.713). CRT significantly reduced the IVMD to 20.3 ± 15.7 (<it>p </it>< 0.001) in average and to 19.8 ± 15.9 ms (<it>p </it>= 0.013) in super-responders with no difference between both groups (<it>p </it>= 0.858). As a marker for intraventricular asynchrony, we assessed the longest intraventricular delay between six basal LV segments. At baseline, there was no difference between average (86.2 ± 30.5 ms) and super-responders (78.8 ± 23.6 ms, <it>p </it>= 0.528). CRT significantly reduced the longest intraventricular delay in both groups - with a significant difference between average (66.2 ± 36.2 ms) and super-responders (32.5 ± 18.3 ms, <it>p </it>= 0.022). Multivariate logistic regression analysis identified the longest intraventricular delay one day after device implantation as an independent predictor of superior response to CRT (<it>p </it>= 0.038).</p> <p>Conclusions</p> <p>A significant reduction of the longest intraventricular delay correlates with superior response to CRT.</p