Titin domains with reduced core hydrophobicity cause dilated cardiomyopathy

The underlying genetic defect in most cases of dilated cardiomyopathy (DCM), a common inherited heart disease, remains unknown. Intriguingly, many patients carry single missense variants of uncertain pathogenicity targeting the giant protein titin, a fundamental sarcomere component. To explore the deleterious potential of these variants, we first solved the wild-type and mutant crystal structures of I21, the titin domain targeted by pathogenic variant p.C3575S. Although both structures are remarkably similar, the reduced hydrophobicity of deeply buried position 3575 strongly destabilizes the mutant domain, a scenario supported by molecular dynamics simulations and by biochemical assays that show no disulfide involving C3575. Prompted by these observations, we have found that thousands of similar hydrophobicity-reducing variants associate specifically with DCM. Hence, our results imply that titin domain destabilization causes DCM, a conceptual framework that not only informs pathogenicity assessment of gene variants but also points to therapeutic strategies counterbalancing protein destabilization.

Structure of the mycobacterial ESX-5 type VII secretion system pore complex

The ESX-5 type VII secretion system is a membrane-spanning protein complex key to the virulence of mycobacterial pathogens. However, the overall architecture of the fully assembled translocation machinery and the composition of the central secretion pore have remained unknown. Here, we present the high-resolution structure of the 2.1-megadalton ESX-5 core complex. Our structure captured a dynamic, secretion-competent conformation of the pore within a well-defined transmembrane section, sandwiched between two flexible protein layers at the cytosolic entrance and the periplasmic exit. We propose that this flexibility endows the ESX-5 machinery with large conformational plasticity required to accommodate targeted protein secretion. Compared to known secretion systems, a highly dynamic state of the pore may represent a fundamental principle of bacterial secretion machineries.

Across scales: novel insights into kidney health and disease by structural biology

Over the past decades, structural biology methods such as X-ray crystallography and cryo-electron microscopy have been increasingly used to study protein functions, molecular interactions, physiological processes, and disease mechanisms. This review outlines a selection of structural biology methods, highlights recent examples of how structural analyses have contributed to a more profound understanding of the machinery of life, and gives a perspective on how these methods can be applied to investigate functions of kidney molecules and pathogenic mechanisms of renal diseases.

Structure and assembly of ESCRT-III helical Vps24 filaments

ESCRT-III proteins mediate a range of cellular membrane remodeling activities such as multivesicular body biogenesis, cytokinesis, and viral release. Critical to these processes is the assembly of ESCRT-III subunits into polymeric structures. In this study, we determined the cryo-EM structure of a helical assembly of Saccharomyces cerevisiae Vps24 at 3.2-Å resolution and found that Vps24 adopts an elongated open conformation. Vps24 forms a domain-swapped dimer extended into protofilaments that associate into a double-stranded apolar filament. We demonstrate that, upon binding negatively charged lipids, Vps24 homopolymer filaments undergo partial disassembly into shorter filament fragments and oligomers. Upon the addition of Vps24, Vps2, and Snf7, liposomes are deformed into neck and tubular structures by an ESCRT-III heteropolymer coat. The filamentous Vps24 homopolymer assembly structure and interaction studies reveal how Vps24 could introduce unique geometric properties to mixed-type ESCRT-III heteropolymers and contribute to the process of membrane scission events.

The SSRP1 subunit of the histone chaperone FACT is required for seed dormancy in Arabidopsis

SSRP1 is a subunit of the histone chaperone FACT that associates with elongating RNA polymerase II (RNAPII) along the transcribed region of genes. FACT facilitates transcriptional elongation by destabilising nucleosomes in the path of RNAPII, assisting efficient transcription of chromatin templates. In contrast to wild type seeds, freshly harvested seeds of the Arabidopsis ssrp1 mutant germinate efficiently, exhibiting reduced seed dormancy. In line with this phenotype, the ssrp1 seeds have decreased transcript levels of the DOG1 gene, which is a known quantitative trait locus (QTL) for seed dormancy. Analysis of ssrp1 plants harbouring an additional copy of DOG1 show increased levels of DOG1 transcript and consistently more robust seed dormancy. Therefore, our findings indicate that SSRP1 is a novel factor required for the efficient expression of DOG1 and hence a modulator of seed dormancy in Arabidopsis.

The Composition of the Arabidopsis RNA Polymerase II Transcript Elongation Complex Reveals the Interplay between Elongation and mRNA Processing Factors

Transcript elongation factors (TEFs) are a heterogeneous group of proteins that control the efficiency of transcript elongation of subsets of genes by RNA polymerase II (RNAPII) in the chromatin context. Using reciprocal tagging in combination with affinity purification and mass spectrometry, we demonstrate that in Arabidopsis thaliana, the TEFs SPT4/SPT5, SPT6, FACT, PAF1-C, and TFIIS copurified with each other and with elongating RNAPII, while P-TEFb was not among the interactors. Additionally, NAP1 histone chaperones, ATP-dependent chromatin remodeling factors, and some histone-modifying enzymes including Elongator were repeatedly found associated with TEFs. Analysis of double mutant plants defective in different combinations of TEFs revealed genetic interactions between genes encoding subunits of PAF1-C, FACT, and TFIIS, resulting in synergistic/epistatic effects on plant growth/development. Analysis of subnuclear localization, gene expression, and chromatin association did not provide evidence for an involvement of the TEFs in transcription by RNAPI (or RNAPIII). Proteomics analyses also revealed multiple interactions between the transcript elongation complex and factors involved in mRNA splicing and polyadenylation, including an association of PAF1-C with the polyadenylation factor CstF. Therefore, the RNAPII transcript elongation complex represents a platform for interactions among different TEFs, as well as for coordinating ongoing transcription with mRNA processing.

Endogenous Natural Complement Inhibitor Regulates Cardiac Development

Congenital heart defects are a major cause of perinatal mortality and morbidity, affecting >1% of all live births in the Western world, yet a large fraction of such defects have an unknown etiology. Recent studies demonstrated surprising dual roles for immune-related molecules and their effector mechanisms during fetal development and adult homeostasis. In this article, we describe the function of an endogenous complement inhibitor, mannan-binding lectin (MBL)-associated protein (MAp)44, in regulating the composition of a serine protease-pattern recognition receptor complex, MBL-associated serine protease (MASP)-3/collectin-L1/K1 hetero-oligomer, which impacts cardiac neural crest cell migration. We used knockdown and rescue strategies in zebrafish, a model allowing visualization and assessment of heart function, even in the presence of severe functional defects. Knockdown of embryonic expression of MAp44 caused impaired cardiogenesis, lowered heart rate, and decreased cardiac output. These defects were associated with aberrant neural crest cell behavior. We found that MAp44 competed with MASP-3 for pattern recognition molecule interaction, and knockdown of endogenous MAp44 expression could be rescued by overexpression of wild-type MAp44. Our observations provide evidence that immune molecules are centrally involved in the orchestration of cardiac tissue development.

Structural insights into the mechanism of negative regulation of single-box high mobility group proteins by the acidic tail domain

The Drosophila and plant (maize) functional counterparts of the abundant vertebrate chromosomal protein HMGB1 (HMG-D and ZmHMGB1, respectively) differ from HMGB1 in having a single HMG box, as well as basic and acidic flanking regions that vary greatly in length and charge. We show that despite these variations, HMG-D and ZmHMGB1 exist in dynamic assemblies in which the basic HMG boxes and linkers associate with their intrinsically disordered, predominantly acidic, tails in a manner analogous to that observed previously for HMGB1. The DNA-binding surfaces of the boxes and linkers are occluded in “auto-inhibited” forms of the protein, which are in equilibrium with transient, more open structures that are “binding-competent.” This strongly suggests that the mechanism of auto-inhibition may be a general one. HMG-D and ZmHMGB1 differ from HMGB1 in having phosphorylation sites in their tail and linker regions. In both cases, in vitro phosphorylation of serine residues within the acidic tail stabilizes the assembled form, suggesting another level of regulation for interaction with DNA, chromatin, and other proteins that is not possible for the uniformly acidic (hence unphosphorylatable) tail of HMGB1.

The seed dormancy defect of Arabidopsis mutants lacking the transcript elongation factor TFIIS is caused by reduced expression of the DOG1 gene

TFIIS is a transcript elongation factor that facilitates transcription by RNA polymerase II, as it assists the enzyme to bypass blocks to mRNA synthesis. Previously, we have reported that Arabidopsis plants lacking TFIIS exhibit reduced seed dormancy. Among the genes differentially expressed in tfIIs seeds, the DOG1 gene was identified that is a known QTL for seed dormancy. Here we have analysed plants that overexpress TFIIS in wild type background, or that harbour an additional copy of DOG1 in tfIIs mutant background. These experiments demonstrate that the down-regulation of DOG1 expression causes the seed dormancy phenotype of tfIIs mutants.

Reduced expression of the DOG1 gene in Arabidopsis mutant seeds lacking the transcript elongation factor TFIIS

TFIIS is a transcript elongation factor that facilitates transcription by RNA polymerase II through blocks to elongation. Arabidopsis plants lacking TFIIS are affected in seed dormancy, which represents a block to complete germination under favourable conditions. We have comparatively profiled the transcript levels of seeds of tfIIs mutants and control plants. Among the differentially expressed genes, the DOG1 gene was identified that is a QTL for seed dormancy. The reduced expression of DOG1 in tfIIs seeds was confirmed by quantitative RT-PCR and Northern analyses, suggesting that down-regulation of DOG1 expression is involved in the seed dormancy phenotype of tfIIs mutants.

Vasospastic angina: control of disease activity and efficacy of drug treatment using the prolonged hyperventilation test

Sixteen consecutive patients with vasospastic angina underwent a control provocation test in the coronary care unit or the cardiac catheterization laboratory in order to evaluate the disease activity and the efficacy of long-term calcium antagonist treatment. In patients without angina at rest, the prolonged hyperventilation test was negative in 10/10 patients on calcium antagonist treatment (group A + B) and in 4/5 patients without medication (group C). The test was positive in 1/1 patient with angina at rest without medication (group D). However, the test provoked vasospastic angina in 1/5 patients who were asymptomatic without medication. In both the latter patients the prolonged hyperventilation test became negative after the restart of calcium antagonist treatment. During a mean follow-up period of 18 months (range 16-19) after the control hyperventilation test, no relapse of angina at rest, arrhythmias, syncopes, deaths or myocardial infarctions were registered. Thus, a negative test is compatible with low disease activity and/or efficacy of calcium antagonist treatment. Further, the test may reveal a subclinical tendency to coronary artery spasm.

Prinzmetal's variant angina)(PVA). Circadian variation in response to hyperventilation

The study reports on the outcome of hyperventilation tests in a 57-year-old male with Prinzmetal's variant angina, formerly often complicated by ventricular fibrillation. It was found that hyperventilation for a period of 6 min after a delay of 4 to 6 min was followed by the development of ST-elevation and pain, but only when the test was performed in the morning, whereas the outcome of tests performed later in the day were negative. Pretreatment with calcium blockers, nifedipine or verapamil proved effective in preventing the anginal response to the test, also when it was performed in the morning. It is concluded that hyperventilation performed in the early morning, but not later in the day, may prove to be an effective and safe procedure for provoking Prinzmetal's variant angina, and that hyperventilation may be useful in the evaluation of the efficacy of drug therapy.

Fatal mumps myocarditis

A case of fatal mumps myocarditis in a 38-year-old male is reported. The disease started with orchitis, and severe cardiac symptoms developed within 1 1/2 month. The patient died 5 months later from congestive heart failure. The possible interrelation between late stages of viral myocarditis and dilated (congestive) cardiomyopathy is emphasized.

Cardiac sarcoidosis and heart transplantation: a report of four consecutive patients

Heart transplantation (HTx) is a well-established treatment for severe cardiac failure. However, HTx for cardiac sarcoidosis is rare; less than 80 patients have been reported worldwide. In many patients, the diagnosis was not made prior to HTx. The aim of this study was to describe the use of HTx in the treatment of severe cardiac sarcoidosis. The series was comprised of four Caucasian patients (1 male, 3 females), aged 25-57 years. HTx were performed in the period 1990-2006. None of the patients had clinically overt extra-cardiac sarcoidosis. In one patient the diagnosis of sarcoidosis was proven prior to HTx. In three patients, all with dilated cardiomyopathy due to myocardial sarcoidosis, the final diagnosis was obtained by examination of the explanted heart. Arrythmias (supraventricular and ventricular), heart block, mitral valve insufficiency and dilated cardiomyopathy were prominent clinical features. None of the patients had recurrence of sarcoid disease in the allograft. Two patients are long-term survivors and two are deceased, one of primary graft failure, the other from Cytomegalovirus myocarditis. In conclusion, HTx is a viable treatment for cardiac sarcoidosis with end stage cardiac failure. Cardiac sarcoidosis is difficult to diagnose. Myocardial biopsy has a low diagnostic sensitivity. However, when the newest non-invasive diagnostic methods, including magnetic resonance imaging and positron emission tomography, are applied, an endomyocardial biopsy should not be mandatory to make a diagnosis of cardiac sarcoidosis.

Cerebral blood flow in patients with chronic heart failure before and after heart transplantation

BACKGROUND AND PURPOSE

Arterial blood pressure and cardiac output are often reduced in patients with chronic heart failure (CHF). Counterregulatory mechanisms with increased neurohormonal activation and changes in the distribution of cardiac output are assumed to secure vital organ perfusion. However, clinical examination of patients with CHF frequently reveals neurological symptoms with dizziness and memory problems, suggesting altered brain perfusion. In this study we determined whether cerebral blood flow (CBF) is reduced in patients with New York Heart Association (NYHA) functional class III and IV (n=12) compared with healthy control subjects (n=12). Furthermore, we examined whether heart transplantation (n=5) could restore CBF.

METHODS

CBF was estimated by single-photon emission computed tomography and (133)Xe as tracer, and middle cerebral artery velocity was measured by transcranial Doppler ultrasound.

RESULTS

In the CHF patients, CBF was 36+/-1 mL/min per 100 g, corresponding to a 31% reduction compared with the control group (52+/-5 mL/min per 100 g) (P<0.05). After heart transplantation, CBF increased from 35+/-3 mL/min per 100 g before transplantation to 50+/-3 mL/min per 100 g within the first postoperative month (P<0.05).

CONCLUSIONS

We conclude that CBF is substantially, but reversibly, reduced in patients with NYHA class III/IV heart failure. This phenomenon suggests that redistribution of cardiac output inadequately secures brain perfusion in patients with severe CHF.

Macrophage and lymphocyte chimerism in bronchoalveolar lavage cells from human lung allograft recipients

BACKGROUND

Chimerism is suggested to predict a more favourable prognosis in solid organ transplantation.

MATERIAL AND METHOD

Forty-eight bronchoalveolar lavages from 10 patients (5 females and 5 males) who had received sex-mismatched donor lungs were monitored for varying periods of time, of up to 2 years, at regular intervals (median 3.0 (0.5-24) months). To investigate the chimerism in macrophages and lymphocytes in bronchoalveolar lavage cells a cloned 2.12 kilobase large biotinylated Y-chromosome-specific DNA-probe was used for in situ hybridization.

RESULTS

Donor macrophages disappeared in seven patients within the first 6 months after surgery (median 3.0 (1-6) months). But 15% donor macrophages could be detected in one patient 1 year and 10% in 2 patients two years after surgery. Donor lymphocytes disappeared in all patients within 3 months (median 1 (0.5-3) months). There was no correlation between periods or severity of acute rejection and percentage of donor macrophages and donor lymphocytes in bronchoalveolar lavage. None of the patients developed obliterative bronchiolitis.

CONCLUSION

Macrophage chimerism in lung may exist for several years. Whilst our results do not elucidate the role of local macrophage chimerism, they do not currently support the view that chimerism prevents rejection.

[Heart transplantation]

In carefully selected patients with end-stage heart failure heart transplantation has developed from an experimental procedure to standard therapy during the last 30 years. It is currently accepted as a procedure for prolonging life and also for improving quality of life. According to the Registry of the International Society for Heart and Lung Transplantation the overall one-year actuarial survival is 79% and 10-year survival barely 50%. Nine years after the start of the Heart Transplant Program at Rigshospitalet the overall actuarial survival of 157 consecutive patients is 66%. Due to the limited donor access a decline of heart transplant recipients has been recorded during the late nineties. Mechanical replacement of the heart may develop from technological advances and possibly this therapy may gain a complementary status in heart failure, however the human biological replacement is currently the standard.

[Cardiogenic shock in acute myocardial infarction. Time for a more aggressive therapeutic strategy?]

Cardiogenic shock following acute myocardial infarction results in the death of most affected individuals. Longitudinal data suggest that in spite of modern pharmacological inotropic support and thrombolytic regimes, survival from cardiogenic shock has not improved during the last several decades. However, recent observational and limited randomized trial data indicate that some of these high risk patients may derive particular benefit from aggressive percutaneous or surgical revascularisation procedures. This review analyses currently available treatment strategies which appear to hold promise for the future.

Myocardial perfusion scintigraphy as a screening method for significant coronary artery stenosis in cardiac transplant recipients

BACKGROUND

Several studies have explored the feasibility of using myocardial perfusion imaging to detect allograft vasculopathy after heart transplantation. We undertook the present prospective consecutive study to comparatively evaluate the role of serial myocardial perfusion single-photon emission computed tomography (SPECT) scanning and coronary arteriography (CAG) in detecting coronary artery stenosis suitable for coronary angioplasty in heart transplant recipients.

METHODS

Within a 2-week interval during a follow-up period of 5.6 (95% confidence limits 2.1 to 12) years, 255 serial CAGs and myocardial perfusion scintigraphies were performed in 67 patients. Arteriography and scintigraphy were performed once yearly after heart transplantation. We retrospectively analyzed the data.

RESULTS

Myocardial scintigraphy showed pathologic reversible defects in 9 out of 67 patients. Four of these patients had significant (>50% and also >70%) focal segmental stenosis in the middle and proximal parts of the coronary arteries (Type A lesions), 1 had diffuse and circumferential narrowing in the distal parts (Type B lesions), whereas CAG showed no lesions in the remaining 4 patients. The patients with significant Type A lesions were revascularized with percutaneous coronary angioplasty. Coronary arteriography showed that 1 patient had extensive Type A and Type B lesions, whereas myocardial perfusion scans detected no. The predictive value of a negative (normal) SPECT was 98% (95% confidence limits 94% to 100%) for the detection of lesions suited for revascularization.

CONCLUSIONS

Annual myocardial SPECT seems well suited to screen for significant coronary artery stenosis. A SPECT study without reversible defects virtually excludes lesions suitable for coronary artery revascularization.

[Circulatory support with the mechanical heart, "HeartMate"]

Treatment with the mechanical heart, HeartMate, has been introduced in Denmark. Short-term circulatory support can be obtained by intraaortic balloon counterpulsation, an external centrifugal pump and the total artificial heart. Long-term circulatory support can be established by treatment with the HeartMate. The principle of the mechanical heart is simple--a pump is implanted in parallel to the existing heart and connected to external, portable batteries. The patient quickly improves and is brought in an optimal state for transplantation. A few patients have been able to omit the subsequent heart transplantation. The patient's own heart improved during the treatment and the native heart functioned again after the system was explanted. The main complications during treatment are bleeding, infection, thromboembolic events and systemic failure. Permanent, fully implantable mechanical circulatory pumps are under development--which may herald the beginning of a whole new era for treatment of cardiac failure.

Coenzyme Q10 in health and disease

The literature concerning the importance of coenzyme Q10 in health and disease has been reviewed. Usual dietary intake together with normal in vivo synthesis seems to fulfil the demands for Q10 in healthy individuals. The importance of Q10 supplementation for general health has not been investigated in controlled experiments. The literature allows no firm conclusions about the significance of Q10 in physical activity. In different cardiovascular diseases, including cardiomyopathy, relatively low levels of Q10 in myocardial tissue have been reported. Positive clinical and haemodynamic effects of oral Q10 supplementation have been observed in double-blind trials, especially in chronic heart failure. These effects should be further examined. No important adverse effects have been reported from experiments using daily supplements of up to 200 mg Q10 for 6-12 months and 100 mg daily for up to 6 y.

Impact of ubiquinone (coenzyme Q10) treatment on glycaemic control, insulin requirement and well-being in patients with Type 1 diabetes mellitus

AIM

To investigate the effect of ubiquinone (coenzyme Q10) on glycaemic control and insulin requirement in patients with Type 1 diabetes mellitus (DM).

METHODS

We investigated 34 patients with Type 1 DM in a randomized, double-blind, placebo-controlled study. Patients received either 100 mg Q10 or placebo daily for 3 months. The insulin doses were adjusted according to patients' home measurements of blood glucose concentrations and reported experience of hypoglycaemia.

RESULTS

At randomization no differences existed between the Q10 and the placebo groups in age, body mass index (BMI), HbA1c, daily insulin dose or mean daily blood glucose concentration. Serum Q10 concentration increased in the Q10 group (mean +/- SD: 0.9+/-0.2 vs. 2.0+/-1.0 microg/ml, P<0.005), with no change in the placebo group (0.9+/-0.3 vs. 0.9+/-0.3 microg/ml, not significant (NS)). Following intervention no differences existed between the Q10 and the placebo groups regarding HbA1c (7.86+/-0.88 vs. 7.84+/-0.84%), mean daily blood glucose concentrations (8.06+/-1.86 vs. 8.53+/-1.88 mM), mean insulin dose (52.1+/-13.2 vs. 52.6+/-21.4 U), hypoglycaemic episodes (2.0+/-1.8 vs. 2.5+/-2.1 episodes/week), or cholesterol concentrations (4.81+/-0.91 vs. 4.78+/-1.07 mM). Furthermore, no differences existed in the well-being of the patients reported from a visual analogue scale (physical: 0.67+/-0.21 vs. 0.71+/-0.18, psychological: 0.70+/-0.25 vs. 0.73+/-0.24).

CONCLUSION

Q10 treatment does not improve glycaemic control, nor does it reduce insulin requirement, and it can therefore be taken by patients with Type 1 DM without any obvious risk of hypoglycaemia. No major beneficial or unfavourable effects on the investigated parameters could be demonstrated and no major changes in the sense of well-being occurred in the patients.

No effect of antioxidant supplementation in triathletes on maximal oxygen uptake, 31P-NMRS detected muscle energy metabolism and muscle fatigue

A double-blind placebo-controlled cross-over trial was undertaken to evaluate the effect of antioxidant supplementation on maximal oxygen uptake during bicycling, 31-phosphorus nuclear magnetic response spectroscopy (31P-NMRS) detected muscle energy metabolism during plantar flexion and muscle fatigue evaluated by 1-s electrical stimulation at low (10 Hz) and high (50 Hz) frequency. Seven male triathletes received daily oral antioxidant supplementation in capsule form including 100 mg coenzyme Q10 (CoQ10), 600 mg ascorbic acid and 270 mg alpha-tocopherol or placebo over a 6-week interval. Serum concentration of CoQ10 was significantly higher in the antioxidant phase (1.80+/-1 microg x ml(-1), mean +/- SD) than control (0.9+/-0.21 microg ml(-1)) or placebo phase (0.9+/-0.3 microg x ml(-1)) (P<0.01). Maximal oxygen uptake was 63.8+/-3.0 ml x min(-1) x kg(-1) in the control phase, and did not change significantly in the antioxidant (67.6+/-10.8 ml x min(-1) x kg(-1)) or the placebo phase (61.9+/-4.5 ml x min(-1) x kg(-1)). The combined 31P-NMRS/low frequency fatigue test (plantar flexion of the foot) did not show differences in the gastrocnemius muscle pH (6.77+/-0.14), phosphocreatine reduction at the end of exercise (23+/-14% of rest) and half-time for recovery of phosphocreatine (33+/-12 sec) between the placebo and the antioxidant trial. No difference in muscle fatigue at 10 Hz electrical stimulation was found between the three phases. In conclusion, the results demonstrate no effect of antioxidative vitamin supplementation on maximal oxygen uptake, muscle energy metabolism or muscle fatigue in triathletes.

The effect of coenzyme Q10 administration on metabolic control in patients with type 2 diabetes mellitus

A possible relationship between the pathogenesis of type 2 diabetes and coenzyme Q10 (CoQ10) deficiency has been proposed. The aim of this study was to assess the effect of CoQ10 on metabolic control in 23 type 2 diabetic patients in a randomized, placebo-controlled trial. Treatment with CoQ10 100 mg bid caused a more than 3-fold rise in serum CoQ10 concentration (p < 0.001). No correlation was observed between serum CoQ10 concentration and metabolic control. No significant changes in metabolic parameters were observed during CoQ10 supplementation. The treatment was well tolerated and did not interfere with glycemic control, therefore CoQ10 may be used as adjunctive therapy in patients with associated cardiovascular diseases.

High serum coenzyme Q10, positively correlated with age, selenium and cholesterol, in Inuit of Greenland. A pilot study

Greenlanders (Eskimos) have low prevalence of ischaemic heart disease, partly explained by a lower extent of atherosclerosis and a low n-6/n-3 ratio of polyunsaturated fatty acids. As atherosclerosis is also a result of oxidative stress, the total antioxidative readiness could have a substantial impact. From a health survey we chose the subpopulation from the most remote area, where the traditional Greenlandic diet with high intake of sea mammals and fish predominates. The mean (SD) of S-CoQ10 in males was 1.495 (0.529) nmol/ml and 1.421 (0.629) nmol/ml in females, significantly higher (p < 0.001) compared to a Danish population. In a linear multiple regression model the S-CoQ10 level is significantly positively associated with age and S-selenium in males, and S-total cholesterol in females. The high level of CoQ10 in Greenlanders probably reflects diet, since no bioaccumulation takes place, and it could probably be a substantial part of the antioxidative defense.

Inducible nitric oxide synthase (iNOS) in the human heart: expression and localization in congestive heart failure

The inducible nitric oxide (NO) synthase (iNOS or NOS2) generates a prolonged release of large amounts of NO which may be cytotoxic and/or inhibit myocyte contractility. It has been suggested that this mechanism specifically contributes to heart failure caused by dilated cardiomyopathy (DCM). To test this hypothesis we compared the myocardial amount and localization of iNOS in myocardial biopsies from patients with heart failure caused by either DCM or ischemic heart disease (IHD). During heart transplantation, myocardial biopsies collected from the diseased heart after explantation were frozen in liquid nitrogen. Twenty-two patients in NYHA class III-IV were included (DCM: n = 8; IHD: n = 14). In each biopsy, iNOS expression was assessed using reverse transcription polymerase chain reaction (RT-PCR), and visualized by immunohistochemistry. iNOS was detected in all biopsies. Intriguingly, the amount of iNOS mRNA (shown as iNOS cDNA normalized to GADPH cDNA) did not differ significantly between the two groups (DCM 30 +/- 7; IHD 20 +/- 6, mean +/- S.E.M., P > 0.05). Similarly, no inter-group differences in the amount of iNOS protein (Western) were observed. iNOS was invariably located to vascular endothelial and smooth muscle cells. In addition, an iNOS reaction in relation to the myocyte membrane was found in 4 of the 22 patients. These four patients (two from each group) had significantly (P < 0.05) higher iNOS/GADPH ratios (54 +/- 20) than patients without myocyte membrane iNOS reaction (17 +/- 15). In conclusion, iNOS is expressed in the myocardium of all patients with heart failure caused by either DCM or IHD. iNOS is located primarily and invariably in the endothelium and vascular smooth muscle cells of the myocardial vasculature and its expression appears to be associated with the condition of heart failure per se rather than related to the heart failure etiology.

Effect of nitroglycerin in patients with increased pulmonary vascular resistance undergoing cardiac transplantation

Acute right ventricular failure due to persistent pulmonary hypertension is a risk factor for premature death after cardiac transplantation. The purpose of this study was to follow changes in pulmonary haemodynamics in patients with pulmonary hypertension undergoing heart transplantation, and to examine whether postoperative changes can be predicted from a preoperative nitroglycerin (NTG) challenge. Seventeen consecutive patients with NYHA class IV heart failure and pulmonary hypertension (pulmonal vascular resistance (PVR) > 2.5 Wood units) underwent an NTG infusion before cardiac transplantation and were followed up using measurements of pulmonary haemodynamics before, early (24 h) and late (6 months) after cardiac transplantation. The effect of NTG was measured preoperatively and compared with posttransplantation values. Postoperative (24 h) PVR was reduced in all patients when compared with preoperative findings (PVR from 4.1 +/- 0.2 to 1.9 +/- 0.2 Wood units, Mean +/- SEM, p < 0.05). Mean pulmonary artery pressure (mPAP) was lowered in 16 of out 17 patients (41 +/- 2 to 26 +/- 1 mmHg, p < 0.05). None of the parameters were significantly changed during the subsequent 6 months. Postoperative PVR and mPAP were accurately estimated by preoperative NTG infusion (NTG vs 24 h posttranspl: PVR 2.2 +/- 0.2 vs 1.9 +/- 0.2 Wood units, p > 0.05; mPAP 30 +/- 2 vs 26 +/- 1 mmHg, p > 0.05). Heart transplantation candidates with pulmonary hypertension responsive to NTG can be expected to obtain a postoperative immediate fall in pulmonary pressures and PVR. The magnitude of this circulatory improvement can be predicted from a preoperative NTG infusion and is not different from values measured 6 months after transplantation.

[Efficacy and safety of dietary supplementation containing Q10]

The literature concerning the importance of Q10 for health and disease has been reviewed. Dietary intake together with normal in vivo synthesis seems to fulfil the body's demands for Q10 in younger, healthy individuals. The importance of Q10 in general well-being has not been investigated in controlled experiments. The literature allows no firm conclusions about the significance of Q10 in physical activity. In different cardiovascular diseases a positive effect of oral Q10 supplementation has been reported, especially in chronic heart failure. These effects should be further examined. No important adverse side effects have been reported from experiments using daily supplements of up to 200 mg of Q10 for six to twelve months, and 100 mg daily for up to six years.

[Treatment of chronic cardiac insufficiency with coenzyme Q10, results of meta-analysis in controlled clinical trials]

Meta-analysis applied to eight controlled clinical trials of coenzyme Q10 (CoQ10)-treatment of congestive heart failure revealed a significant improvement a several important cardiac parameters such as ejection fraction (EF), stroke volume (SV), cardiac output (CO), cardiac index (CI) and end diastolic volume index (EDVI). Concerning the improvement in SV and CO the average patient in the CoQ10 group had a higher score than respectively 76% and 73% of the patients in the placebo group. The improvement in CO and SV was also significant when considering of homogeneity. Additional controlled clinical trials seem justified which may strengthen the power of the meta-analyses. However, based on available results, it can not be excluded that CoQ10 may have a future role a adjunctive therapy in a dosage of 100-200 mg/day in the treatment of chronic congestive heart failure.

[Clinical results after en block double lung transplantation with direct bronchial revascularization. The first three and a half years' experience in Denmark]

En-bloc double lung transplantation with tracheal anastomosis and direct revascularization of the bronchial arteries to the left internal mammary artery has been carried out in Denmark since June 1992. Forty-seven patients (32 with alfa-1 antitrypsin deficiency, 11 with chronic obstructive pulmonary disease, two with cystic fibrosis and two with primary pulmonary hypertension), 25 men and 22 women, average age 39 years (17-64 years), have received their first double-lung transplant with bronchial artery revascularization. Arteriography of the internal mammary artery and bronchial arteries was performed in 42 (89%) of the patients from 1-150 days after the operation. Successful bronchial artery revascularization was demonstrated arteriographically in 40 patients, in two patients the arteriography failed to show bronchial artery revascularization. Arteriography was not performed in five patients due to early complications and death. Bronchoscopy showed rapid, uncomplicated airway healing in 42 patients. Mucosal necrosis under the tracheal anastomosis was found in three patients, and severe obstructive endobronchial growth of the fungus Aspergillus fumigatus was diagnosed in the last two patients. The one- and two-year survival is 83% (Kaplan-Meier). Eleven patients are dead, five due to pulmonary causes and six due to extra-pulmonary causes. Pulmonary function became normal in nearly all surviving patients between three to six months after the transplantation. In conclusion, en-bloc double-lung transplantation with bronchial artery vascularization has shown good short-term results, and the one- and two-year survival gives hope that a successful bronchial artery revascularization will improve the long-term survival following lung transplantation.

Direct bronchial artery revascularization and en bloc double lung transplantation--surgical techniques and early outcome

BACKGROUND

Lung transplantation including direct bronchial artery revascularization (BAR) has produced promising early results in small clinical series.

METHODS

In Copenhagen primary en bloc double lung transplantation with BAR, with the left mammary artery used as conduit, has been performed in 47 patients from 1992 to the end of 1995. After introduction of the bloc into the recipient, the mammary-to-bronchial artery anastomosis is performed as the first anastomosis, allowing perfect exposure and early reperfusion. Internal mammary-bronchial artery arteriography has been performed routinely after operation.

RESULTS

Bronchoscopic examination performed in all patients documented normal airway healing in 42, disturbed in two, and complicated in three. Arteriography performed in 42 patients demonstrated complete BAR in 25, incomplete in 15, and failed BAR in 2. Failed BAR was associated with complicated airway healing. The 1- and 2-year survival rate (Kaplan-Meyer) is 83%. Eleven patients have died, only one within 30 days. The total incidence of bronchiolitis obliterans syndrome at 3 years (with Kaplan-Meier technique) is 33%. Successful BAR has also been performed with an adjusted technique in a limited number of heart-lung and single lung transplantations. Our total experience of BAR in any type of lung transplantation includes 65 patients with an arteriographic BAR success rate of 94% (50 of 53 examined patients).

CONCLUSIONS

Experience has improved the surgical technique and has made BAR reliable and safe, be it double lung, single lung, or heart-lung transplantation. Early results are good, but only follow-up will show if long-term results after lung transplantation will be improved by BAR. Already today, en bloc double lung transplantation with BAR is a viable alternative to sequential bilateral lung transplantation.

Dietary coenzyme Q10 supplementation alters platelet size and inhibits human vitronectin (CD51/CD61) receptor expression

Improved cardiovascular morbidity and mortality have been observed in several clinical studies of dietary supplementation with coenzyme Q10 (CoQ10, ubiquinone). Several mechanisms have been proposed to explain the effects of CoQ10, but a comprehensive explanation of its cardioprotective properties is still lacking. One attractive theory links ubiquinone with the inhibition of platelets. The effect of CoQ10 intake on platelet size and surface antigens was examined in human volunteers. Study participants received 100 mg of CoQ10 twice daily in addition to their usual diet for 20 days. Receptor expression was measured by flow cytometry with monoclonal murine anti-human antibodies CD9 (p24), CD42B (Ib), CD41b (IIb), CD61 (IIIa), CD41a (IIb/IIIa), CD49b (VLA-2), CD62p (P selectin), CD31 (PECAM-1), and CD51/CD61 (vitronectin). An increase of total serum CoQ10 level (from 0.6 +/- 0.1 to 1.8 +/- 0.3 micrograms/ml; p < 0.001) was found at protocol termination. Fluorescence intensity was higher for the large platelets when compared with the whole platelet population. Significant inhibition of vitronectin-receptor expression was observed consistently throughout ubiquinone treatment. Reduction of platelet size was observed at the end of CoQ10 supplementation. Inhibition of the platelet vitronectin receptor and a reduction of the platelet size are direct evidence of a link between dietary CoQ10 intake and platelets. These findings may not be fully explained by the known antioxidant and bioenergetic properties of CoQ10. Diminished vitronectin-receptor expression and reduced platelet size resulting from CoQ10 therapy may contribute to the observed clinical benefits in patients with cardiovascular diseases.

Dose-related decrease of serum coenzyme Q10 during treatment with HMG-CoA reductase inhibitors

Coenzyme Q10 (ubiquinone) the essential mitochondrial redox-component and endogenous antioxidant, packaged into the LDL + VLDL fractions of cholesterol, has been suggested as an important anti-risk factor for the development of atherosclerosis as explained by the oxidative theory. Forty-five hypercholesterolemic patients were randomized in a double-blind trial in order to be treated with increasing dosages of either lovastatin (20-80 mg/day) or pravastatin (10-40 mg/day) over a period of 18 weeks. Serum levels of coenzyme Q10 were measured parallel to the levels of cholesterol at baseline on placebo and diet and during active treatment. A dose-related significant decline of the total serum level of coenzyme Q10 was found in the pravastatin group from 1.27 +/- 0.34 at baseline to 1.02 +/- 0.31 mmol/l at the end of the study period (mean +/- S.D.), P < 0.01. After lovastatin therapy the decrease was significant as well and more pronounced, from 1.18 +/- 0.36 to 0.84 +/- 0.17 mmol/l, P < 0.001. Although HMG-CoA reductase inhibitors are safe and effective within a limited time horizon, continued vigilance of a possible adverse consequence from coenzyme Q10 lowering seems important during long-term therapy.

Could coenzyme Q10 affect hemostasis by inhibiting platelet vitronectin (CD51/CD61) receptor?

Improved cardiovascular morbidity and mortality have been observed in several clinical studies of dietary supplementation with coenzyme Q10 (CoQ10, ubiquinone). Several mechanisms have been proposed to explain the effects of CoQ10. One attractive theory links ubiquinone with the inhibition of platelets. The effect of CoQ10 intake on platelet surface antigens, and certain hemostatic parameters was examined in 15 humans and 10 swine. Study participants received 100 mg of CoQ10 twice daily in addition to their usual diet for 20 days resulting in a three-fold increase of total serum CoQ10 level. We observed a decline in plasma fibronectin (-20.2%), thromboxane B2 (-20.6%), prostacyclin (-23.2%), and endothelin-1 (-17.9%) level. Significant inhibition of vitronectin receptor expression was observed consistently throughout ubiquinone treatment. Inhibition of the platelet vitronectin receptor is a direct evidence of a link between dietary CoQ10 intake, platelets, and hemostasis. These findings may contribute to the observed clinical benefits by a diminished incidence of thrombotic complications in such patients.

Treatment of congestive heart failure with coenzyme Q10 illuminated by meta-analyses of clinical trials

The purpose of this was to investigate the effect of coenzyme Q10 (CoQ10) in patients with congestive heart failure (CHF) by measuring the possible improvement of certain relevant hemodynamic heart parameters. A statistic aggregation method know as a meta-analysis was used to measure the changes in the cardiac parameters. To begin with we collected the total number of randomized controlled trials and from a total of 14 studies published in the period of 1984-1994, eight studies met our inclusion criteria. The rest were excluded because of a lack of data which made a meta-analysis impossible. The relevant effect parameters investigated were stroke volume (SV), cardiac output (CO), ejection fraction (EF), cardiac index (CI), end diastolic volume index (EDVI), systolic time intervals (PEP/LVET) and total work capacity (Wmax). Seven meta-analyses were performed, one for each of the parameters, and the calculated effect sizes were all positive. Statistical significance could be demonstrated for all of the parameters except the PEP/LVET and Wmax thereby indicating an improvement of greater or lesser magnitude in the CoQ10 group as opposed to the placebo group. Accordingly, the average patient in the CoQ10 group had a better score with regard to SV and CO than 76 and 73% respectively of the patients in the placebo group. In conclusion, supplemental treatment of CHF with CoQ10 is consistent with an improvement of SV, EF, CO, CI and EDVI. Homogeneity could be established for SV and CO. Additional clinical trials of the effect of CoQ10 on CHF are necessary, but, on the basis of the evidence currently available, the possibility remains that CoQ10 will receive a well-documented role as an adjunctive treatment of CHF.

Severe hemolysis caused by graft-derived anti-B production after lung transplantation

Anti-B antibody causing sever hemolytic anemia and renal failure was found in the serum of a blood group B patient who had received a bilateral lung transplant from a blood group O donor. Although the donor origin of the antibody was not confirmed, it is likely that the anti-B antibody was produced by donor passenger B lymphocytes.

Coenzyme Q10 protects coronary endothelial function from ischemia reperfusion injury via an antioxidant effect

BACKGROUND

Cardiac ischemia reperfusion (I/R) injury causes coronary vascular dysfunction. Coenzyme Q10 (CoQ), which preserves cardiac mechanical function after I/R, recently has been recognized as a free radical scavenger. We hypothesized that CoQ protects coronary vascular reactivity after I/R via an antioxidant mechanism.

METHODS

Rats were pretreated with either CoQ (20 mg/kg intramuscular and 10 mg/kg intraperitoneal [CoQ group]) or a vehicle (Control) before the experiment. Isolated perfused rat hearts were subjected to 25 minutes of global normothermic ischemia and 40 minutes of reperfusion. The reperfusion-induced oxidative burst was directly assessed by lucigenin enhanced chemiluminescence. Coronary flow was measured at equilibration and after reperfusion with or without bradykinin, an endothelium-dependent vasodilator, and sodium nitroprusside (SNP), an endothelium-independent vasodilator. The effect of intracoronary infusion of hydrogen peroxide (H2O2 0.1 mumol/gm body weight given over 5 minutes), simulating the free radical burst after I/R, also was evaluated.

RESULTS

I/R decreased the bradykinin-induced change in coronary flow (-5% +/- 4% versus 26% +/- 3% at equilibration; p < 0.05) and the SNP-induced change (+20% +/- 6% versus +56% +/- 5% at equilibration; p < 0.05). The coronary vasculature after H2O2 infusion revealed a similar loss in vasodilatory responsiveness (+4% +/- 4% in response to bradykinin, +35% +/- 8% in response to SNP; p < 0.05 versus equilibration). Pretreatment with CoQ improved BK-induced vasorelaxation after I/R (+12% +/- 2%; p < 0.05 versus control I/R) or H2O2 infusion (18% +/- 4%; p < 0.05 versus control I/R) but failed to improve SNP-induced vasorelaxation. The CoQ pretreatment decreased the I/R-induced maximal free radical burst (9.3 +/- 0.8 x 10(3) cpm versus 11.5 +/- 1.1 x 10(3) cpm; p < 0.05) during the early period of reperfusion.

CONCLUSIONS

Endothelium-dependent vasorelaxation is more sensitive than endothelium-independent relaxation to I/R injury. Via a direct antioxidant effect, CoQ preserved endothelium-dependent vasorelaxation by improving tolerance to I/R injury.

Hemostatic changes after dietary coenzyme Q10 supplementation in swine

Improved cardiovascular morbidity and mortality have been observed in several clinical studies of dietary supplementation with coenzyme Q10 (CoQ10). We elucidated the effect of CoQ10 on certain hemostatic parameters that may influence the progression of heart disease. Twelve Yorkshire swine were randomized to receive diet supplementation with either CoQ10 or placebo for 20 days. Blood samples were obtained at baseline and at the end of the feeding period. At the end of the protocol, there were no significant differences in hemostatic parameters in the placebo group. A significant increase in total serum CoQ10 level (from 0.39 +/- 0.06 to 0.96 +/- 0.04 microgram/ml, p < 0.001) was noted after the feeding period in the CoQ10-supplemented group. We observed significant inhibition of ADP-induced platelet aggregation (-9.9%) and a decrease in plasma fibronectin (-20.2%), thromboxane B2 (TXB2, -20.6%), prostacyclin (-23.2%), and endothelin-1 (ET-1, -17.9%) level. There were no changes in the plasma concentrations of the natural antithrombotics [antithrombin-III (AT-III), protein S, and protein C] after CoQ10 supplementation. CoQ10 supplementation in a dose of 200 mg daily is associated with mild antiaggregatory changes in the hemostatic profile. Clinical beneficial effects of CoQ10 may be related in part to a diminished incidence of thrombotic complications.

Elucidation of a tripartite mechanism underlying the improvement in cardiac tolerance to ischemia by coenzyme Q10 pretreatment

Coenzyme Q10, which is involved in mitochondrial adenosine triphosphate production, is also a powerful antioxidant. We hypothesize that coenzyme Q10 pretreatment protects myocardium from ischemia reperfusion injury both by its ability to increase aerobic energy production and by protecting creatine kinase from oxidative inactivation during reperfusion. Isolated hearts (six per group) from rats pretreated with either coenzyme Q10, 20 mg/kg intramuscularly and 10 mg/kg intraperitoneally (treatment) or vehicle only (control) 24 and 2 hours before the experiment were subjected to 15 minutes of equilibration, 25 minutes of ischemia, and 40 minutes of reperfusion. Developed pressure, contractility, compliance, myocardial oxygen consumption, and myocardial aerobic efficiency were measured. Phosphorus 31 nuclear magnetic resonance (31P-NMR) spectroscopy was used to determine adenosine triphosphate and phosphocreatine concentrations as a percentage of a methylene diphosphonic acid standard. Hearts were assayed for myocardial coenzyme Q10 and myocardial creatine kinase activity at end equilibration and at reperfusion. Treated hearts showed higher myocardial coenzyme Q10 levels (133 +/- 5 micrograms/gm ventricle versus 117 +/- 4 micrograms/gm ventricle, p < 0.05). Developed pressure at end reperfusion was 62% +/- 2% of equilibration in treatment group versus 37% +/- 2% in control group, p < 0.005. Preischemic myocardial aerobic efficiency was preserved during reperfusion in treatment group (0.84 +/- 0.08 mm Hg/(microliter O2/min/gm ventricle) vs 1.00 +/- 0.08 mm Hg/(microliter O2/min/gm ventricle) at equilibration, p = not significant), whereas in the control group it fell to 0.62 +/- 0.07 mm Hg/(microliter O2/min/gm ventricle, p < 0.05 vs equilibration and vs the treatment group at reperfusion. Treated hearts showed higher adenosine triphosphate and phosphocreatine levels during both equilibration (adenosine triphosphate 49% +/- 2% for the treatment group vs 33% +/- 3% in the control group, p < 0.005; phosphocreatine 49% +/- 3% in the treatment group vs 35% +/- 3% in the control group, p < 0.005) and reperfusion (adenosine triphosphate 18% +/- 3% in the treatment group vs 11% +/- 2% in the control group, CTRL p < 0.05; phosphocreatine 45% +/- 2% in the treatment group vs 23% +/- 3% in the control group, p < 0.005). Creatine kinase activity in treated hearts at end reperfusion was 74% +/- 3% of equilibration activity vs 65% +/- 2% in the control group, p < 0.05). Coenzyme Q10 pretreatment improves myocardial function after ischemia and reperfusion. This results from a tripartite effect: (1) higher concentration of adenosine triphosphate and phosphocreatine, initially and during reperfusion, (2) improved myocardial aerobic efficiency during reperfusion, and (3) protection of creatine kinase from oxidative inactivation during reperfusion.

Ability of antimyosin scintigraphy monitoring to exclude acute rejection during the first year after heart transplantation

BACKGROUND

Antimyosin Fab fragment has been shown to bind to myosin leaked from necrotic cardiac cells but not to myosin in undamaged cells. The purpose of this investigation was to evaluate indium 111-antimyosin Fab fragment scintigraphy as a noninvasive technique in the diagnosis of acute rejection after heart transplantation. Simultaneous endomyocardial biopsy served as the gold standard.

METHODS

Twenty-two patients had scintigraphic studies at weeks 3 to 4, 6, 10, 26, and 52, but the next 16 patients underwent scintigraphy more often, that is, at all scheduled biopsies performed from week 3 to week 26 after transplantation. From analysis of the first 70 studies, an interstudy decrease in the patient's heart-to-lung ratio was classified as normal, that is, no rejection, whereas an unchanged or increased heart-to-lung ratio was considered pathologic.

RESULTS

By use of this definition of negative and positive scintigraphic results, prospective analysis of 88 conclusive, consecutive studies showed 6 true- and 31 false-positive studies (prevalence of rejection 8%), giving a low predictive value of a pathologic change in heart-to-lung ratio. Of the 51 studies with decreasing heart-to-lung ratio only 1 was a false negative, giving a predictive value of a negative study of 98% (95% confidence limits 90% to 100%).

CONCLUSIONS

In conclusion, antimyosin scintigraphy is a promising noninvasive technique in the routine surveillance of acute heart rejection. Because of many false-positive results in the studies, biopsy should be used as a control for a pathologic heart-to-lung ratio.

[Lung transplantation. Indications, preoperative evaluation and postoperative treatment]

Thirty-six heart-lung and lung transplantations have been performed in Denmark from January 1992 to January 1994. Heart-lung transplantations was initially carried out in patients with pulmonary vascular diseases. Single lung, double lung and heart-lung transplantation have become therapeutical alternatives and the indications have been expanded to terminal patients with pulmonary diseases. Careful selection of patients and donors, careful surgical techniques and a stringent immunosuppressive treatment have minimized the perioperative mortality. Daily lung function measurements, transbronchial biopsies and bronchoalveolar lavage have created possibilities for an early and safe diagnosis of infections and rejections. A high frequency of obliterative bronchiolitis with loss of pulmonary function is still a serious and unsolved problem. Intensive investigations with the aim of understanding, preventing and treating obliterative bronchiolitis are going on.

Orthotopic cardiac transplantation reverses abnormal reflex regulation of the microvasculature in the lower leg

OBJECTIVE

The aim was to investigate the effect of cardiac transplantation on reflex control of lower leg subcutaneous blood flow.

METHODS

The reflex regulation of subcutaneous blood flow of the lower leg was studied in 11 patients following orthotopic cardiac transplantation, in 11 patients with severe congestive heart failure (New York Heart Association functional class III or IV), and in 11 healthy subjects. Four patients were studied before and after cardiac transplantation. Cause of heart failure was classified as idiopathic dilated cardiomyopathy in all heart failure patients and in all the cardiac transplant patients before transplantation. Blood flow was measured by the local 133xenon washout method in the supine position and during 45 degrees head up tilt.

RESULTS

When performing head up tilt without activation of the local nervous venoarteriolar axon reflex in patients with congestive heart failure, the relative subcutaneous blood flow increased abnormally, by 50(SD 25)%, but in patients after cardiac transplantation a normal decrease was seen [-28(13)%, p < 0.001]. The responses in the transplant group were similar to those observed in normal controls with a decrease in blood flow [-32(15)%; NS]. Head up tilt with simultaneous activation of the local venoarteriolar axon reflex increased blood flow [31(22)%] in patients with heart failure as compared to the decrease in blood flow found in the transplants [-44(17)%, p < 0.001]. The decrease of blood flow was not significantly different between the transplant group and control subjects [-53(19)%; NS].

CONCLUSIONS

These results indicate that abnormal reflex regulation in severe congestive heart failure with peripheral vasodilation of the lower leg during orthostasis is reversed and even normalised after cardiac transplantation. The haemodynamic consequence may be a regaining of an oedema-protective mechanism that eliminates the stress (capillary hypertension) on the microcirculation seen in severe heart failure.