Bengt Rundqvist

Cardiac Sympathetic Nerve Function in Congestive Heart Failure

BACKGROUND Increased availability of norepinephrine (NE) for activation of cardiac adrenoceptors (increased cardiac adrenergic drive) and depletion of myocardial NE stores may contribute to the pathophysiology and progression of congestive heart failure. This study used a comprehensive neurochemical approach to examine the mechanisms responsible for these abnormalities. METHODS AND RESULTS Subjects with and without congestive heart failure received intravenous infusions of [(3)H]NE. Cardiac spillover, reuptake, vesicular-axoplasmic exchange, and tissue stores of NE were assessed from arterial and coronary venous plasma concentrations of endogenous and [(3)H]-labeled NE and dihydroxyphenylglycol. Tyrosine hydroxylase activity was assessed from plasma dopa, and NE turnover was assessed from measurements of NE metabolites. NE release and reuptake were both increased in the failing heart; however, the efficiency of NE reuptake was reduced such that cardiac spillover of NE was increased disproportionately more than neuronal release of NE. Cardiac NE stores were 47% lower and the rate of vesicular leakage of NE was 42% lower in the failing than in the normal heart. Cardiac spillover of dopa and NE turnover were increased similarly in congestive heart failure. CONCLUSIONS Increased neuronal release of NE and decreased efficiency of NE reuptake both contribute to increased cardiac adrenergic drive in congestive heart failure. Decreased vesicular leakage of NE, secondary to decreased myocardial stores of NE, limits the increase in cardiac NE turnover in CHF. Decreased NE store size in the failing heart appears to result not from insufficient tyrosine hydroxylation but from chronically increased NE turnover and reduced efficiency of NE reuptake and storage.

Increased Cardiac Adrenergic Drive Precedes Generalized Sympathetic Activation in Human Heart Failure

BACKGROUND Previous studies with radiotracer methods have indicated increases in cardiac norepinephrine (NE) and renal NE spillover in patients with severe congestive heart failure (CHF). However, data on the regional sympathetic profile in early stages of CHF are limited. In this study, sympathetic function in the heart, kidneys, and skeletal muscle was evaluated in patients with mild-to-moderate CHF and compared with that in patients with severe CHF and healthy subjects. METHODS AND RESULTS Total body and regional NE spillover from the heart and kidney was assessed with isotope dilution with steady state infusions of [3H]NE. Sympathetic nerve traffic to the skeletal muscle vascular bed (MSA) was recorded intraneurally. Cardiac NE spillover in patients with mild-to-moderate CHF (n = 21) was increased threefold versus that in healthy subjects (n = 12, P < .05), whereas total body and renal NE spillover and MSA did not differ from those in healthy subjects. In the severe CHF group (n = 12), cardiac NE spillover was increased fourfold (P < .05), and total body and renal NE spillover and MSA were high compared with both mild-to-moderate CHF subjects and healthy subjects (P < .05 for both). Fractional extraction of [3H]NE across the heart was reduced by approximately 40% in both CHF groups versus control subjects (P < .05). CONCLUSIONS These results indicate a selective increase in cardiac adrenergic drive (increased amounts of transmitter available at neuroeffector junctions) in patients with mild-to-moderate CHF. This increase appears to precede the augmented sympathetic outflow to the kidneys and skeletal muscle found in advanced CHF.

Increased sympathetic nerve activity in renovascular hypertension.

BACKGROUND Increased sympathetic nerve activity may contribute to the progression of renovascular hypertension. Because previous results have been inconclusive, we investigated whether renovascular hypertensives show increased total and regional sympathetic nerve activity. METHODS AND RESULTS Sixty-five patients underwent renal angiography and measurements of plasma renin activity and angiotensin II in conjunction with estimation of sympathetic nerve activity by means of radiotracer dilution and intraneural recordings of muscle sympathetic nerve activity (MSNA). Age-matched healthy subjects (n=15) were examined for comparison. Total body norepinephrine (NE) spillover, an index of overall sympathetic nerve activity, was increased by 100% and MSNA by 60% in the hypertensive patients compared with healthy subjects (P<0.01 for both). A subgroup of 24 patients with well-defined renovascular hypertension (cured or improved hypertension after renal angioplasty) showed similar increases in total body NE spillover compared with the group at large. Patients with arterial plasma renin activity and angiotensin II levels above median had higher values for total body NE spillover than patients below median (P<0.01). CONCLUSIONS This study unequivocally demonstrates elevated sympathetic nerve activity in patients with renovascular hypertension. The adrenergic overactivity may contribute to the blood pressure elevation and perhaps also to the high cardiovascular mortality in renovascular hypertension.

Increased cardiovascular mortality in hypertensive patients with renal artery stenosis. Relation to sympathetic activation, renal function and treatment regimens.

BACKGROUND Previous studies in hypertensive patients with renovascular disease have shown both elevated sympathetic nerve activity and increased cardiovascular mortality. OBJECTIVE The aim of the present study was to assess long-term survival in hypertensive patients with renal artery stenosis in relation to sympathetic activation, renal function and treatment regimens. SUBJECTS AND METHODS A total of 169 consecutive patients aged 54 +/- 1 years with hypertension underwent a clinical investigation for renovascular hypertension including renal angiography and measurement of bilateral renal renin secretion. In 107 of these patients, arterial plasma concentrations of noradrenaline were measured. The mean follow-up time was 7.1 +/- 0.3 years and survival data were available in all patients up to May 1997. For comparison, healthy age-matched normotensive controls were examined. RESULTS Arterial noradrenaline concentrations were threefold elevated in hypertensive patients with renal artery stenosis compared to healthy controls (P < 0.01). During the follow-up time, 44 patients died. Cardiovascular mortality accounted for 75% of all deaths. The risk ratio for overall mortality in hypertensive patients with renal artery stenosis compared to the normal population of Sweden, matched for age, was 3.3 (2.4-4.4), whereas the risk ratio for cardiovascular mortality was 5.7 (3.9-8.0). The arterial plasma concentration of noradrenaline was 3.11 +/- 0.30 pmol/ml in patients who died compared to 3.84 +/- 0.26 pmol/ml in survivors. Reduced renal function and age were independent predictors of death. Survival did not differ between patients undergoing intervention with either renal angioplasty or surgical reconstruction for renal artery stenosis and patients not undergoing intervention. CONCLUSIONS Although sympathetic nerve activity is elevated in hypertensive patients with renal artery stenosis, our results do not suggest that this adrenergic over-activity is directly linked to the observed high cardiovascular mortality. Mortality in hypertensive patients with renovascular disease remains high whether an interventional treatment is performed or not, possibly due to the concomitant coronary disease.

Growth factors and interleukin-6 across the lung circulation in pulmonary hypertension

The aim of our study was to assess the levels of growth factors and interleukin (IL)-6 across the pulmonary circulation in patients with pulmonary arterial hypertension (PAH) and correlate them with clinical and haemodynamic data and outcome. Simultaneous arterial and pulmonary arterial blood samples in patients with PAH (n = 44) and controls (n = 20) were obtained during right heart catheterisation. Vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF)-BB, transforming growth factor (TGF)-β1 and IL-6 were measured using ELISA. Arterial median (interquartile range) values for VEGF, PDGF-BB, TGF-β1 and IL-6 were significantly higher in patients (377 (218–588) versus 9.0 pg·mL−1; 1,955 (1,371–2,519) versus 306 (131–502) pg·mL−1; 26.42 (11.3–41.1) versus 7.0 (1.8–18.4) ng·mL−1; and 3.98 (0.7–8.1) versus 0.7 pg·mL−1, respectively; p<0.001 for all variables). There was a consistent step-up of VEGF, PDGF-BB and TGF-β1 across the lungs in PAH patients (p<0.001, p = 0.002 and p<0.001, respectively), whereas in controls, arterial and pulmonary arterial serum levels of IL-6 and growth factors were similar (statistically nonsignificant). In multivariate analysis, increased IL-6 levels predicted mortality (hazard ratio 1.08 (95% confidence interval 1.02–1.15); p = 0.012). Our findings indicate increased release and/or decreased clearance of growth factors at the lung vascular level, which may contribute to vascular remodelling in PAH.

Mesenteric Organ Production, Hepatic Metabolism, and Renal Elimination of Norepinephrine and Its Metabolites in Humans

Abstract: This study used regional differences in plasma concentrations of norepinephrine and its metabolites to examine how production of the transmitter by sympathetic nerves, in particular, those innervating mesenteric organs, is integrated with metabolism by the liver and elimination by the kidneys. Higher concentrations of norepinephrine, its glycol metabolites 3,4‐dihydroxyphenylglycol and 3‐methoxy‐4‐hydroxyphenylglycol and their sulfate conjugates in portal venous than arterial plasma indicate substantial production of norepinephrine by mesenteric organs (15.5 nmol/min). Much lower concentrations of norepinephrine and its glycol metabolites in plasma leaving than entering the liver indicate their efficient hepatic removal (20 nmol/min). Higher concentrations of vanillylmandelic acid in the hepatic outflow than inflow indicate that this metabolic end product is produced largely from the norepinephrine and glycol metabolites removed by the liver. Renal elimination of vanillylmandelic acid (18–20 nmol/min), produced mainly by the liver (17 nmol/min), and of 3‐methoxy‐4‐hydroxyphenylglycol sulfate (7–9 nmol/min), produced largely by mesenteric organs (7 nmol/min), comprised 86–91% of the total renal elimination of norepinephrine metabolites. The results show that mesenteric organs produce about one‐half of the norepinephrine formed in the body. The liver removes substantial amounts of circulating norepinephrine and its glycol metabolites and converts these compounds to vanillylmandelic acid, which is then eliminated from the body by the kidneys. The sulfate conjugates are also metabolic end products eliminated by the kidneys. However, these metabolites are produced by extrahepatic tissues, in particular, mesenteric organs, which represent a significant source of sulfate‐conjugated norepinephrine and 3,4‐dihydroxyphenylglycol, and the main source of sulfate‐conjugated 3‐methoxy‐4‐hydroxyphenylglycol.

Firing Properties of Single Muscle Vasoconstrictor Neurons in the Sympathoexcitation Associated With Congestive Heart Failure

BACKGROUND Congestive heart failure (CHF) in humans is associated with a marked sympathoexcitation, including an augmented muscle sympathetic nerve activity (MSNA) in intraneural multiunit recordings. In the present study, single-unit recording was used to evaluate whether the firing properties of individual muscle vasoconstrictor neurons can reveal underlying mechanisms for this increase in MSNA. METHODS AND RESULTS Eight patients with CHF (NYHA class II to IV; left ventricular ejection fraction, 29+/-5%, mean+/-SEM) were studied. In standard multiunit recordings, MSNA burst incidence (bursts/100 heartbeats) ranged from 65% to 100% (88+/-5%). Using selective tungsten microelectrodes, we made recordings from 16 single muscle vasoconstrictor axons. Mean unit firing probability (ie, the percentage of cardiac intervals in which a single axon fired) was 54.5+/-5.2% (range, 21 to 89%), and mean firing frequency was 0.98+/-0.22 Hz (0.14 to 3.86 Hz), both of which were higher than seen previously in healthy subjects (P<0.001). Although single neurons occasionally generated multiple spikes per sympathetic burst, such multiple firing was rare and was not different from that seen in healthy subjects. CONCLUSIONS An increased firing frequency of individual vasoconstrictor neurons is one mechanism for the increased number of multiunit MSNA bursts at rest in CHF. The neurons discharge in more diastoles than in healthy subjects (ie, firing probability is increased), but the likelihood of discharging >1 impulse per sympathetic burst is not increased. Despite the intense multiunit activity at rest, the firing characteristics of individual vasoconstrictor axons indicate a remaining capacity for transient increases of MSNA in CHF.

Everolimus With Reduced Calcineurin Inhibitor in Thoracic Transplant Recipients With Renal Dysfunction: A Multicenter, Randomized Trial

Background. The proliferation signal inhibitor everolimus offers the potential to reduce calcineurin inhibitor (CNI) exposure and alleviate CNI-related nephrotoxicity. Randomized trials in maintenance thoracic transplant patients are lacking. Methods. In a 12-month, open-labeled, multicenter study, maintenance thoracic transplant patients (glomerular filtration rate ≥20 mL/min/1.73m2 and <90 mL/min/1.73 m2) >1 year posttransplant were randomized to continue their current CNI-based immunosuppression or start everolimus with predefined CNI exposure reduction. Results. Two hundred eighty-two patients were randomized (140 everolimus, 142 controls; 190 heart, 92 lung transplants). From baseline to month 12, mean cyclosporine and tacrolimus trough levels in the everolimus cohort decreased by 57% and 56%, respectively. The primary endpoint, mean change in measured glomerular filtration rate from baseline to month 12, was 4.6 mL/min with everolimus and −0.5 mL/min in controls (P<0.0001). Everolimus-treated heart and lung transplant patients in the lowest tertile for time posttransplant exhibited mean increases of 7.8 mL/min and 4.9 mL/min, respectively. Biopsy-proven treated acute rejection occurred in six everolimus and four control heart transplant patients (P=0.54). In total, 138 everolimus patients (98.6%) and 127 control patients (89.4%) experienced one or more adverse event (P=0.002). Serious adverse events occurred in 66 everolimus patients (46.8%) and 44 controls (31.0%) (P=0.02). Conclusion. Introduction of everolimus with CNI reduction offers a significant improvement in renal function in maintenance heart and lung transplant recipients. The greatest benefit is observed in patients with a shorter time since transplantation.

The effect of physical activity or exercise on key biomarkers in atherosclerosis--a systematic review.

OBJECTIVE This systematic review aimed to summarize published papers on the effect of physical activity (PA)/exercise on key atherosclerotic factors in patients with risk factors for or established cardiovascular disease (CVD). METHODS Studies involving PA and cytokines, chemokines, adhesion molecules, CRP and angiogenic factors were searched for in Medline and Cochrane library. Original human studies of more than 2 weeks of PA intervention were included. Study quality was assessed according to the GRADE system of evidence. RESULTS Twenty-eight papers fulfilled the inclusion criteria. PA decreases the cytokines, tumor necrosis factor-a (TNF-a), interleukin-6 (IL-6), and interferon-y IFN-y (high, moderate and low evidence, respectively). The effect of PA on chemokines; stromal derived factor-1 (SDF-1), interleukin-8 (IL-8) (insufficient evidence) and monocyte chemoattractant protein-1 (MCP-1) (low evidence) was inconclusive. Aerobic exercise decreased the adhesion molecules, vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) (moderate and high evidence, respectively), while effects of PA on E- and P-selectin were inconclusive. PA decreases C-reactive protein (CRP) (high evidence). The angiogenic actors, endothelial progenitor cells (EPCs) are increased (high evidence) and VEGF is decreased (moderate evidence) by PA. The effect of PA on these factors seems to depend on the type and duration of exercise intervention and patient factors, such as presence of ischemia. CONCLUSION As presented in this review, there is a high level of evidence that physical activity positively affects key players in atherosclerosis development. These effects could partly explain the scientifically proven anti-atherogenic effects of PA, and do have important clinical implications.

Two-Year Outcomes in Thoracic Transplant Recipients After Conversion to Everolimus With Reduced Calcineurin Inhibitor Within a Multicenter, Open-Label, Randomized Trial

Background. Use of the mammalian target of rapamycin inhibitor everolimus with an accompanying reduction in calcineurin inhibitor (CNI) exposure has shown promise in preserving renal function in maintenance thoracic transplant patients, but robust, long-term data are required. Methods. In a prospective, open-label, multicenter study, thoracic transplant recipients more than or equal to 1 year posttransplant with mild-to-moderate renal insufficiency were randomized to continue their current CNI-based immunosuppression or convert to everolimus with predefined CNI exposure reduction. After a 12-month core trial, patients were followed up to month 24 after randomization. Results. Of 245 patients who completed the month 12 visit, 235 patients (108 everolimus and 127 controls) entered the 12-month extension phase. At month 24, mean measured glomerular filtration rate had increased by 3.2±12.3 mL/min from the point of randomization in everolimus-treated patients and decreased by 2.4±9.0 mL/min in controls (P<0.001), a difference that was significant within both the heart and lung transplant subpopulations. During months 12 to 24, 5.6% of everolimus patients and 3.1% of controls experienced biopsy-proven acute rejection (P=0.76). There were no significant differences in the rate of adverse events or serious adverse events (including pneumonia) between groups during months 12 to 24. Conclusions. Converting maintenance thoracic transplant recipients to everolimus with low-exposure CNI results in a renal benefit that is sustained to 2 years postconversion, with significantly improved measured glomerular filtration rate in both heart and lung transplant patients. Despite reductions of more than 50% in CNI exposure, there was no marked loss of efficacy. The safety profile of the everolimus-based regimen was acceptable.