Weight loss impacts risky decisions in obesity

BACKGROUND & AIMS

Risky decision making is shaped by individual psychological and metabolic state. Individuals with obesity show not only altered risk behavior, but also metabolic and psychological abnormalities. The aim of the present study was to investigate whether a substantial weight loss in individuals with severe obesity will 1) normalize their metabolic and psychological state and 2) will change their pattern of decision guidance.

METHODS

We assessed the effect of glycated hemoglobin (HbA1c) and mood on risk behavior in individuals with obesity (n = 62, 41 women; BMI, 46.5 ± 4.8 kg/m2; age, 44.9 ± 14.7 years) before and after 10-weeks weight loss intervention.

RESULTS

Results showed that this intervention reduced participants' risk behavior, which was significantly predicted by their changes in BMI. Before intervention, mood, but not HbA1c significantly predicted decisions. After the weight loss, mood no longer, but HbA1c significantly predicted decisions.

CONCLUSION

Our findings shed light on the psychological and metabolic mechanisms underlying altered risky decision making in severe obesity and can inform the development of strategies in the context of weight loss interventions.

Combination of cryothermy with radiofrequency energy sources during hybrid atrial fibrillation ablation- impact on lesion quality and outcomes

Background

Whereas pulmonary vein isolation lays the groundwork of endocardial atrial fibrillation (AF) ablation, it leaves patients undertreated. Additional substrate modification of the left atrium is often required, but lesion gaps and non-transmurality limit restoration of sinus rhythm. Moreover, some low voltage areas and conduction abnormalities are located exclusively on the epicardial aspect, and endocardial ablation alone does not address these issues. Our hybrid endo-/epicardial ablation strategy overcomes all these shortcomings.

Purpose

To test if the combination of epicardial cryo and radiofrequency (RF) ablation (dual) further improves the quality of ablation lines, and if the combined endo-/epicardial ablation can treat intractable cases of AF.

Methods

Twenty-six patients (13 paroxysmal, 13 long-persistent; 20 patients with 1–5 prior endocardial AF ablations) first underwent epicardial, total thoracoscopic beating heart ablation (TTA). Lesion sets included bilateral PVI, left atrial appendage closure, as well as superior (roof) and inferior (floor) interpulmonary vein lines. Roof and floor lines were alternatingly ablated by dual energy or RF only. Three months post TTA, endocardial mapping with optional gap closure completed this two-stage hybrid concept.

Results

Intraoperatively, 24 of 40 (60%) previous left or right endocardial PVIs were found incomplete. Apart from two post-TTA pacemaker insertions and one mini-thoracotomy for bleeding, respectively, no major morbidity was observed during follow up. The full protocol of the hybrid concept was applied in 24 patients. Forty-five of 47 (96%) epicardial PVIs were found gap-less during endocardial mapping, and the remaining 2 PVIs were readily re-ablated. In contrast, only 32 of 46 (70%) roof and floor lines were complete, and endocardial touch up was required in one of three patients. Of note, dual energy lines were more likely to be complete than RF only lines (17 of 22, 77%, vs. 15 of 24, 62%; p NS). Among 19 patients with continuous monitoring, only 4 (21%) had any AF burden including two patients within blanking period and before endocardial gap closure. The remaining 7 patients without continuous monitoring never experienced any symptoms related to recurrent AF, and serial Holter EKG were without pathology.

Conclusions

Hybrid ablation and dual energy provides a strong armamentarium for extra-pulmonary venous triggers of AF. Linear ablation lines were more likely to be gap-less and transmural, if dual energy sources were used. Dual energy TTA is highly efficient to restore sinus rhythm in patients with prior failed endocardial AF ablation. However, one of three patients will require endocardial gap closure to realize the full benefit of our two-stage hybrid concept. Further study will evaluate if dual energy lines outside the box can improve outcome in these challenging cases of intractable AF.

Funding Acknowledgement

Type of funding source: None

Pyruvate potentiates inotropic effects of isoproterenol and Ca(2+) in rabbit cardiac muscle preparations

Catecholamines and elevated extracellular Ca(2+) concentration ([Ca(2+)](o)) augment contractile force by increased Ca(2+) influx and subsequent increased sarcoplasmic reticulum (SR) Ca(2+) release. We tested the hypothesis that pyruvate potentiates Ca(2+) release and inotropic response to isoproterenol and elevated [Ca(2+)](o), since this might be of potential importance in a clinical setting to circumvent deleterious effects on energy demand during application of catecholamines. Therefore, we investigated isometrically contracting myocardial preparations from rabbit hearts at 37 degrees C, pH 7.4, and a stimulation frequency of 1 Hz. At a [Ca(2+)](o) of 1.25 mM, pyruvate (10 mM) alone increased developed force (F(dev)) from 1.89 +/- 0.42 to 3.62 +/- 0.62 (SE) mN/mm(2) (n = 8, P < 0.05) and isoproterenol (10(-6) M) alone increased F(dev) from 2.06 +/- 0. 55 to 25.11 +/- 2.1 mN/mm(2) (P < 0.05), whereas the combination of isoproterenol and pyruvate increased F(dev) overproportionally from 1.89 +/- 0.42 to 33.31 +/- 3.18 mN/mm(2) (P < 0.05). In a separate series of experiments, we assessed SR Ca(2+) content by means of rapid cooling contractures and observed that, despite no further increase in F(dev) by increasing [Ca(2+)](o) from 8 to 16 mM, 10 mM pyruvate could still increase F(dev) from 26.4 +/- 6.8 to 29.7 +/- 7. 1 mN/mm(2) (P < 0.05, n = 9) as well as the Ca(2+) load of the SR. The results show that the positive inotropic effects of pyruvate potentiate the inotropic effects of isoproterenol or Ca(2+), because in the presence of pyruvate, Ca(2+) and isoproterenol induced larger increases in inotropy than can be calculated by mere addition of the individual effects.

Influence of cyclosporine A on contractile function, calcium handling, and energetics in isolated human and rabbit myocardium

OBJECTIVE

The immunosuppressive drug Cyclosporine A (CsA) is a key substance in pharmacological therapy following solid organ transplantation and has been suggested to prevent cardiac hypertrophy. We investigated the direct effects of CsA on myocardial function, because these are largely unknown.

METHODS

In multicellular cardiac muscle preparations from end-stage failing and non-failing human hearts as well as from non-failing rabbit hearts we investigated the effects of CsA on contractile performance, sarcoplasmic reticulum (SR) Ca2+-load, cytosolic calcium transients, calcium sensitivity of the myofilaments, and myocardial oxygen consumption.

RESULTS

In failing human muscle preparations there was a concentration dependent decrease in contractile force; the maximal effect amounted to 55.6+/-6.4% of control while EC50 was reached at 1.0+/-0.3 nM (n=6). These concentrations are at and even below the therapeutic plasma levels. CsA decreased the aequorin light signal in human failing trabeculae to 71.5+/-5.9% (n=5), indicating decreased calcium transients. Estimation of the SR calcium load via measurement of rapid cooling contractures revealed a decrease to 84.4+/-6.5% in failing human preparations (n=6). Measurements of both decreased SR calcium load and force development in presence of CsA were also observed in four non-failing human muscle preparations. In rabbit muscle preparations (n=8), developed force decreased to 50.2+/-7.7% (n=8, EC50: 1.9+/-0.4 nM) and rapid cooling contractures to 74.0+/-7.4% of control at 100 nmol/l CsA. No direct effects were observed on myofilament calcium sensitivity nor on maximal force development of permeabilized preparations from the rabbit (n=7). Oxygen consumption measurements showed that CsA decreased the economy of contraction to 76.4+/-7.9% in rabbit preparations (n=8).

CONCLUSIONS

CsA causes a direct cardio-depressive effect at clinically relevant concentrations, most likely due to altered handling of Ca2+ by the SR.

Frequency-dependence of myocardial energetics in failing human myocardium as quantified by a new method for the measurement of oxygen consumption in muscle strip preparations

Diastolic dysfunction at high heart rates may be associated with increased myocardial energy consumption. Frequency-dependent changes of isometric force and oxygen consumption (MVO2) were investigated in strip preparations from endstage failing human hearts exhibiting various degrees of diastolic dysfunction. MVO2 was determined by a new method which was validated. When stimulation rate was increased from 40 to 200 min-1 (n=7), developed force decreased from 16.5+/-4.3 to 7.9+/-2.9 mN/mm2 (P<0.01), diastolic force increased from 15.9+/-3.2 to 22.0+/-3.0 mN/mm2 (P<0.01), and total MVO2 increased from 2.6+/-0.6 to 4.7+/-0.9 ml/min/100 g (P<0.025). Resting MVO2 and resting force were 1.8+/-0.4 ml/min/100 g and 15.9+/-3.0 mN/mm2, respectively. After addition of 30 mm 2,3-butanedione monoxime (BDM) to inhibit crossbridges, resting MVO2 and resting force decreased by 46% (P<0.05) and 15% (P<0.01), respectively, indicating the presence of active force generation in unstimulated failing human myocardium. In each muscle preparation, there was a significant correlation between force-time integral (FTI) and total MVO2 (r=0.96+/-0.01). The strength of these correlations did not vary with the contribution of diastolic FTI to total FTI. The ratio of activity related MVO2 to developed FTI, an inverse index of the economy of contraction, increased depending on the rise of diastolic FTI at higher stimulation rates. In conclusion, in failing human myocardium, diastolic force development is occurring at the same energy expenditure as systolic force generation. Therefore, in muscle preparations with disturbed diastolic function economy of contraction decreases with higher stimulation rates, depending on the rise of diastolic force.