Clinical research projects at a German medical faculty: follow-up from ethical approval to publication and citation by others

BACKGROUND

Only data of published study results are available to the scientific community for further use such as informing future research and synthesis of available evidence. If study results are reported selectively, reporting bias and distortion of summarised estimates of effect or harm of treatments can occur. The publication and citation of results of clinical research conducted in Germany was studied.

METHODS

The protocols of clinical research projects submitted to the research ethics committee of the University of Freiburg (Germany) in 2000 were analysed. Published full articles in several databases were searched and investigators contacted. Data on study and publication characteristics were extracted from protocols and corresponding publications.

RESULTS

299 study protocols were included. The most frequent study design was randomised controlled trial (141; 47%), followed by uncontrolled studies (61; 20%), laboratory studies (30; 10%) and non-randomised studies (29; 10%). 182 (61%) were multicentre studies including 97 (53%) international collaborations. 152 of 299 (51%) had commercial (co-)funding and 46 (15%) non-commercial funding. 109 of the 225 completed protocols corresponded to at least one full publication (total 210 articles); the publication rate was 48%. 168 of 210 identified publications (80%) were cited in articles indexed in the ISI Web of Science. The median was 11 citations per publication (range 0-1151).

CONCLUSIONS

Results of German clinical research projects conducted are largely underreported. Barriers to successful publication need to be identified and appropriate measures taken. Close monitoring of projects until publication and adequate support provided to investigators may help remedy the prevailing underreporting of research.

Regional myocardial perfusion defects during exercise, as assessed by three dimensional integration of morphology and function, in relation to abnormal endothelium dependent vasoreactivity of the coronary microcirculation

OBJECTIVE

To test the hypothesis that scintigraphic regional myocardial perfusion defects during exercise in patients with normal coronary angiography may be related to abnormal endothelium dependent vasoreactivity of the corresponding myocardial territory in response to cold pressor testing.

METHODS

38 patients were classified into two groups according to the presence or absence of exercise induced scintigraphic myocardial perfusion defects. A cold pressor test was done in all patients during routine coronary angiography, followed by dynamic positron emission tomography to establish coronary blood flow mediated vasoreactivity of the epicardial coronary artery and the myocardial territories supplied by the left anterior descending, left circumflex, and right coronary arteries.

RESULTS

28 patients had regional myocardial perfusion defects while 10 had normal scintigraphic imaging. The three dimensional scintigraphic fusion image revealed 49 regional myocardial perfusion defects with a mean (SD) reversibility of the original stress defect of 20 (3)%. In patients with exercise induced regional myocardial perfusion defects, the responses of epicardial luminal area and regional myocardial blood flow (RMBF) to cold pressor testing were reduced compared with patients with normal perfusion imaging (epicardial luminal area: 5.2 (1.2) to 4.2 (0.86) mm2 v 4.7 (0.5) to 5.8 (0.5) mm2; RMBF: 0.75 (0.16) to 0.78 (0.20) ml/g/min v 0.75 (0.15) to 1.38 (0.26) ml/g/min; p < or = 0.03, respectively). In patients with regional abnormal scintigraphic perfusion, the corresponding RMBF response to cold pressor testing was more severely impaired than the mean myocardial blood flow in the remaining two vascular territories, but the difference was not significant (0.75 (0.16) to 0.78 (0.20) ml/g/min v 0.75 (0.10) to 0.87 (0.12) ml/g/min; NS). The endothelium independent increase in RMBF induced by glyceryl trinitrate did not differ between patients with exercise induced myocardial perfusion defects and those with normal perfusion images (0.75 (0.16) to 0.94 (0.09) ml/g/min v 0.75 (0.15) to 0.94 (0.09) ml/g/min; NS). There was a highly significant correlation between the endothelium dependent responses of RMBF to cold pressor testing and the severity of exercise induced scintigraphic regional myocardial perfusion defects (r = 0.95, p = 0.001).

CONCLUSIONS

Exercise induced scintigraphic regional myocardial perfusion defects in patients with angina but normal coronary angiography may be related to abnormal endothelium dependent vasoreactivity of the corresponding myocardial territory.

Efficacy and safety of intravenous levosimendan compared with dobutamine in severe low-output heart failure (the LIDO study): a randomised double-blind trial

BACKGROUND

Levosimendan, a novel calcium sensitiser, improves myocardial contractility without causing an increase in myocardial oxygen demand. We compared the effects of levosimendan and dobutamine on haemodynamic performance and clinical outcome in patients with low-output heart failure.

METHODS

Patients were recruited into a multicentre, randomised, double-blind, double-dummy, parallel-group trial. Under continuous haemodynamic monitoring, an initial loading dose of levosimendan of 24 microg/kg was infused over 10 min, followed by a continuous infusion of 0.1 microg kg(-1) min(-1) for 24 h. Dobutamine was infused for 24 h at an initial dose of 5 microg kg(-1) min(-1) without a loading dose. The infusion rate was doubled if the response was inadequate at 2h. The primary endpoint was the proportion of patients with haemodynamic improvement (defined as an increase of 30% or more in cardiac output and a decrease of 25% or more in pulmonary-capillary wedge pressure) at 24 h. Analyses were by intention to treat.

FINDINGS

103 patients were assigned levosimendan and 100 dobutamine. The primary haemodynamic endpoint was achieved in 29 (28%) levosimendan-group patients and 15 (15%) in the dobutamine group (hazard ratio 1.9 [95% CI 1.1-3.3]; p=0.022). At 180 days, 27 (26%) levosimendan-group patients had died, compared with 38 (38%) in the dobutamine group (0.57 [0.34-0.95]; p=0.029).

INTERPRETATION

In patients with severe, low-output heart failure, levosimendan improved haemodynamic performance more effectively than dobutamine. This benefit was accompanied by lower mortality in the levosimendan group than in the dobutamine group for up to 180 days.

Clinical outcome of radiosynoviorthesis: a meta-analysis including 2190 treated joints

A variety of indications for radiosynoviorthesis have been reported in literature, but the clinical outcome differs and depends on the primary disease and the pre-existing degenerative changes. This metaanalysis was carried out to establish groups for radiosynoviorthesis based on clinical outcome with respect to primary disease, clinical stage and the pre-existing degenerative changes. The literature search was carried out using the MEDLINE search term 'radionuclide synovectomy'. Based on reports in the literature we determined groups for radiosynoviorthesis for clinical use. Our literature list comprised 2190 joints that were treated with radiosynoviorthesis. The overall response rate for all treated joints was 72.5+/-17%. The mean improvement rate for the treated joints in rheumatoid arthritis was 66.7+/-15.4%. For osteoarthritis the success rate was 56+/-11%, with better results in case of minimal radiological changes. Radiosynoviorthesis in patients with changes according to Steinbrocker I and II was successful in 72.8+/-12.3%, and in 64+/-17.3%, respectively. Steinbrocker III and IV had a mean success rate of 52.4+/-23.6%. In the case of haemophilia and Willebrand's disease a reduction of joint bleedings and factor usages after radiosynoviorthesis was evident in 91+/-4.3%. In patients with pigmented villonodular synovitis radiosynoviorthesis was successful in 77.3+/-25.3%. It is concluded that radiosynoviorthesis provides better results in rheumatoid arthritis than in osteoarthritis. Minimal or moderate changes according to Steinbrocker stages I and II respond better to radionuclide therapy than do stages III and IV. Deformed or unstable joints might fail treatment and therefore surgical interventions should be considered. Close cooperation with orthopaedists and rheumatologists is necessary to consider radiosynoviorthesis in each patient to ensure optimal medical care.

Impact of oligomerization on the function of the human serotonin transporter

The formation of oligomeric structures has been proposed for a large number of membrane proteins, including G-protein-coupled receptors and ion channels. Biochemical studies employing gel filtration, cross-linking or co-immunoprecipitation techniques showed that the serotonin [5-hydroxytryptamine (5-HT)] transporter is also capable of forming oligomers. We investigated whether the human serotonin transporter (hSERT) can be visualized as an oligomer in the plasma membrane of intact cells. To test this working hypothesis, we generated fusion proteins of hSERT and spectral variants of green fluorescent protein [cyan and yellow fluorescent proteins (CFP and YFP, respectively)]. When expressed in HeLa or HEK-293 cells, the resulting fusion proteins (CFP-hSERT and YFP-hSERT) were inserted into the plasma membrane and were indistinguishable from wild-type hSERT on functional testing (5-HT uptake assays, inhibition of 5-HT uptake by blockers such as imipramine). Oligomers were visualized by fluorescence resonance energy transfer (FRET) microscopy in living cells using complementary methods. Interestingly, oligomerization was not confined to hSERT; FRET was also observed between CFP-and YFP-labelled rat gamma-aminobutyric acid transporter. Gel filtration experiments showed that most of the protein was recovered as higher molecular weight complexes; almost no monomeric form was detected. This indicates that the homo-oligomeric form is the favoured state of hSERT in living cells. The formation of oligomers was not significantly affected by co-incubation with transporter substrates or blockers. Based on our observations, oligomer formation might not be essential for the physiological function of the transporter protein, the re-uptake of substrates. Furthermore, we conclude that constitutive oligomer formation might be a general property of Na(+)/Cl(-)-dependent neurotransmitter transporters.

Beta-blocking agents vs. antiarrhythmic interventions in heart failure complicated by arrhythmias

Approximately 40-50% of the patients with end-stage cardiac failure (either ischemic or nonischemic) die suddenly and unexpectedly, most probably from ventricular fibrillation. It is unclear whether the complex ventricular arrhythmias observed in large numbers of these patients were related to the mode of death. Theoretically, it seems quite reasonable to attempt to suppress the development of life-threatening ventricular arrhythmias (e.g., sustained ventricular tachycardia or ventricular fibrillation) in those patients. If antiarrhythmic drug therapy is ineffective, alternative antiarrhythmic interventions (antiarrhythmic surgery or implantation of an automatic implantable cardioverter defibrillator) should be considered. In patients with so-called potentially malignant ventricular arrhythmias (e.g., nonsustained ventricular tachycardia), antiarrhythmic drug therapy remains controversial as presently there is no definitive proof that this therapy prolongs life or reduces the incidence of sudden cardiac death. In patients with end-stage cardiac failure, beta-blockade can result in a decrease in resting tachycardia, improvement in clinical heart failure symptoms, and increase in work load capacity. It remains controversial whether treatment with these agents can also improve prognosis and prevent sudden cardiac death. Therefore, at this time, only patients in the earlier stages of this clinical syndrome and with clinical signs of markedly increased sympathetic tone can be treated with low doses of beta-blockers.

Effect of ascorbic acid on endothelial dysfunction of epicardial coronary arteries in chronic smokers assessed by cold pressor testing

BACKGROUND

In chronic smokers there is evidence for increased formation of oxygen-derived free radicals within the vessel wall impairing endothelial function. It has been suggested that the inactivation of endothelium-derived nitric oxide by oxygen free radicals contributes to endothelial dysfunction. Hence, we tested the hypothesis that in chronic smokers the antioxidant ascorbic acid could improve abnormal endothelial function of epicardial coronary arteries.

METHODS AND RESULTS

Thirty-one patients (mean age 57 +/- 9 years) referred for routine diagnostic catheterization for evaluation of chest pain and without angiographically significant coronary artery stenoses were randomly assigned to one of the study groups to assess vasomotor response of epicardial coronary arteries due to cold pressor testing (CPT) before and after intravenous infusion of 3 g of ascorbic acid or 100 ml x 0.9% saline infusion. In 6 controls (mean age 55 +/- 3 years) CPT led to a similar increase in luminal area before and after ascorbic acid administration (26.5 +/- 15.0 vs. 28.4 +/- 17.7%, p = NS). In 15 chronic smokers (mean age 55 +/- 9 years), CPT induced a decrease in the luminal area of -18.5 +/- 6.3%. This flow-dependent vasoconstriction was significantly reversed to 7.7 +/- 6.2% (p < or = 0.03) vasodilation after intravenous ascorbic acid administration. In 10 chronic smokers (mean age 57 +/- 11 years) saline infusion (placebo) did not have a significant effect on CPT-induced vasoconstriction (-12.7 +/- 5.1 vs. -13.1 +/- 5.1%, p = NS). The CPT-induced increase in luminal area in chronic smokers after ascorbic acid infusion was significant compared to controls and placebo (each p < or = 0.05). Our assessment of endothelium-independent responses to nitroglycerin revealed no significant differences between the single study groups (p = NS).

CONCLUSION

In chronic smokers acute intravenous administration of ascorbic acid significantly improves CPT-induced coronary endothelium-dependent dysfunction. According to the current understanding, this effect is due to improved cellular redox imbalance and prevention of nitric oxide inactivation in the endothelium and subendothelial space.

Histamine excites groups III and IV afferents from the cat knee joint depending on their resting activity

The effect of histamine on the sensory activity of primary afferents was studied in normal and acutely inflamed cat knee joints. A subpopulation of groups III and IV articular afferents could be activated by close-arterial bolus injections of histamine: units with a high resting activity (about 100/min) were particular sensitive to histamine and were excited even by 3.3 fg histamine. The lower the resting discharges of groups III and IV units both from normal and acutely inflamed joints, the higher the dose of histamine (up to 3.3 or 33 microg) necessary to excite the nerve fibres. Thirty-seven of 39 units without any resting activity were completely insensitive to histamine. In contrast to its clear excitatory effect, histamine caused only minor changes in the responses to joint movements. Movement-evoked activity remained unchanged in 22 of 28 units, 1 unit was sensitized and 5 units showed reduced activity after histamine (3.3 microg). The present results support the notion that histamine may participate in the mediation of pain from injured or inflamed tissue. It is remarkable that histamine has a profound excitatory action on a proportion of both groups III and IV articular afferents without changing their sensitivity to joint movements.

[Current status of endocarditis prevention]

There are currently no randomized and carefully controlled human trials to definitively prove that endocarditis prophylaxis is efficient. Furthermore, most cases of endocarditis are not attributable to a medical procedure. Thus, even with a high level of application of endocarditis prophylaxis only a minority of cases could be prevented. Endocarditis is a rare disease. On the other hand, its morbidity is increasing! In addition, infective endocarditis remains still a major medical concern because of its mortality between 5% and 76%. In addition, in up to 40% of all patients suffering from endocarditis one or more heart valves have to be replaced in the following 5 to 8 years. Without treatment endocarditis has a lethality of 100%. Therefore, there is worldwide agreement that endocarditis prophylaxis is necessary. Combining the recommendations of the German and the American Heart Association, as well as the results of the European consensus conferences, with newer insights into the pathophysiology of endocarditis the following aspects are elucidated: depending on their risk of endocarditis patients are allocated into 3 groups. In the first group there are patients with prosthetic cardiac valves, patients who suffered from previous endocarditis and patients with complex cyanotic congenital heart disease and surgically constructed shunts or conduits of the aorta and/or pulmonary circulation. In these high-risk patients the prophylactic regimen for dental, oral, respiratory tract procedures is oral amoxycillin. In genitourinary and gastrointestinal procedures ampicillin and gentamicin i.v. is recommended. In patients with mostly congenital cardiac malformations, acquired valvular dysfunction, hypertrophic obstructive cardiomyopathy and mitral valve prolapse or thickened leaflets and valvular regurgitation oral amoxycillin is recommended for all medical procedures (second group). The third group consists of patients with isolated secundum atrial defect, previous coronary bypass graft surgery, patients with cardiac pacemakers or defibrillators. In this patient cohort the individual risk of endocarditis is not higher than in the general population. Therefore, endocardits prophylaxis is not recommended.

Usefulness of carvedilol in unstable angina pectoris

The safety and efficacy of adding oral carvedilol (25 mg twice daily) to standardized treatment of unstable angina was assessed in a multicenter, randomized, double-blind, placebo- controlled trial on 116 patients with acute unstable angina. Patients were monitored in an intensive care unit and underwent 48-hour Holter monitoring to assess transient ischemia. Carvedilol as adjunctive therapy resulted in a significant reduction of median heart rate (65 vs 75 beats/min, p <0.05), mean systolic blood pressure (133 vs 130 mm Hg, p <0.05), and mean rate-pressure product (8,337 vs 10,042, p <0.05). Carvedilol reduced the ischemic burden during 48 hours of treatment by 75% (49 vs 204 minutes), including a 36% reduction of patients with ischemic episodes (p <0.05), a 66% reduction of the mean number of ischemic episodes (8 vs 24, p <0.05), and a 76% reduction in the mean duration of ischemic episodes (50 vs 205 minutes, p <0.05). Side effects occurred in 8 of 59 patients (13.6%) in the carvedilol group and in 5 of 54 patients (8.8%) given placebo. Although not significant, the early onset of maximal blood pressure reduction and the delayed effect on heart rate were closely correlated to drug-induced hypotension and bradycardia in the carvedilol group. Thus, carvedilol as an adjunctive to standardized treatment effectively reduces heart rate and blood pressure, and thus the ischemic burden in patients with unstable angina pectoris, but requires close monitoring of patients at risk for bradycardia or hypotension.

[Therapy for heart failure]

The treatment of congestive heart failure focuses on three steps: 1. Elimination of the precipitating cause or mechanism, and/or treatment of the underlying disease respectively. 2. Treatment of the failing heart syndrome itself. We shall concern ourselves with pharmacotherapy, omitting technical and surgical aspects. 3. Prophylactic treatment of complications, such as thromboembolism and arrhythmias. Drugs for the treatment of heart failure can be classified as follows: 1. Diuretics 2. Vasodilators 3. Neurohumoral Inhibitors 4. Inotropic drugs. Diuretics improve symptoms and exercise capacity and probably survival. They are the drug of first choice in acute and chronic heart failure. Potassium supplementation is necessary. Renal function needs to be monitored. The aldosterone antagonist spironolactone has probably important effects upon the myocardium. It retards fibrous tissue development and improves prognosis. Vasodilators unload the heart and improve contractile geometry and hemodynamics, thereby lessening symptoms. Prognosis, however, is not affected. They are indispensable in acute heart failure. In longterm treatment only the combination of nitrates with hydralazin has been shown to be effective. Angiotensin converting enzyme inhibitors combine vasodilation with neurohumoral inhibition. They are most effective in improving symptoms, exercise capacity and surviving chronic heart failure. If side effects (cough, allergy) prevent their use, then angiotensin II receptor antagonists can be used with equal benefit. However, both groups of drugs impair renal function and cannot be given in advanced renal failure or renal artery stenosis. Beta-receptor antagonists, previously considered contraindicated in heart failure are today amongst the most important drugs in heart failure. They improve survival and retard the need for cardiac transplantation in advanced failure. Their use, however, is rather difficult requiring extremely slow dose titration beginning with very low doses. Inotropic drugs are today mainly used in acute failure and cardiogenic shock. In longterm treatment only the digitalisglycosides have been shown to be effective in improving symptoms, exercise capacity and the general clinical course. Often antiarrhythmic treatment is necessary. Here amiodarone is the drug of choice today if beta blockers do not suffice. Prophylactic anticoagulation is indicated in all cases NYHA III and IV, with large hearts already in II. Future developments may include new inotropes, the ANP-system, and cytokines, as well as gene therapy for correction of myocardial phenotype change.

[Clinical diagnosis of heart failure]

The clinical diagnosis of heart failure is based upon history and physical examination. Careful questioning and examination requires understanding of the pathophysiology of this systemic disorder. Symptoms and signs of congestive heart failure need to be differentiated from the manifestations of the underlying cardiovascular disorder. Only then will the specific signs and symptoms be unraveled. Symptoms arise from pulmonary congestion and peripheral or organ-underperfusion. Findings related to congestion can be found over the lungs (rales, pleural effusion), or at the jugular veins displaying either frank central venous pressure elevation or paradoxic inspiratory venous pressure rise (Kussmaul sign), or the more discrete sign of right, left of biventricular failure, the hepatojugular reflux. Dilatation and hypertrophy of the cardiac chambers can clinically easily and reliably be assessed by careful palpation. Galopprhythm, right and/or left ventricular in origin, is a particularly reliable sign of a failing ventricle. While a presystolic, atrial sound indicates merely elevated resistance to ventricular filling, i.e. the presence diastolic dysfunction or increased chamber filling, is the ventricular diastolic galopp a reliable sign of ventricular failure. Especially the appearance of a quadruple rhythm or a summation galopp can be considered both highly specific as well as prognostically dubious. Relative mitral and/or tricuspid insufficiency as a sign of ventricular dilatation needs to be differentiated from organic valve disease. This requires often echocardiography. Oedema of cardiac origin is symmetric and more pronounced in the evening. It arises both from left and from right ventricular failure. History and physical examination are both reliable tools in the initial diagnosis, as well as during follow-up and for control of therapeutic measures. Technical methods, such as chest x-ray, echocardiography or else are used for quantification and documentation. Properly applied and utilized they allow the physician to sharpen his clinical acumen, thus allowing for both a reliable diagnosis and a semi-quantitative estimation of ventricular size, enddiastolic and atrial, as well as pulmonary pressures and valve function.

[New developments in diagnosis of coronary heart disease--3D fusion image]

The interpretation of three-dimensional (3D) structures of the coronary tree and the myocardium by a clinician demands a subjective visual integration of two-dimensional (2D) images of cardiac diagnostic procedures like coronary angiography and myocardial scintigraphy. Although in the conventional analysis of 2D display scintigraphic myocardial perfusion segments are arbitrarily assigned to three major coronary artery systems, the standard myocardial perfusion distribution territories correspond with the individual pathologic-anatomic coronary tree in only 50-60% of the patients. Hence, the mental integration of both 2D images of coronary angiography and myocardial scintigraphy does not necessarily allow an accurate assignment of particular myocardial perfusion regions to the corresponding vessels. For an objective assignment of each vessel segment of the coronary tree to the corresponding myocardial regions, we have developed a 3D "fusion image" technique and applied it to patients with coronary artery disease. Cause-and-effect relationships may be more obvious with 3D data fusion and may enable an easier comparison of anatomy and physiology. Preliminary results demonstrate that our newly developed 3D fusion image is useful for accurate assignment of coronary vessel segments to the corresponding myocardial perfusion regions and suggest that it may allow the clinician a comprehensive and accurate assessment of the patient's myocardial status.

[Patent foramen ovale: conservative or surgical therapy?]

Notwithstanding the difficulties in definitely confirming paradoxical embolism, the association between patent foramen ovale (PFO) and cryptogenic stroke has repeatedly been demonstrated in clinical studies. Moreover, the recurrence rate of cerebral ischemia in patients with PFO and an unexplained stroke was found to be 3-4% per year in two recently published series. With the exception of right atrial pressure elevation in the setting of major pulmonary embolism, a reliable risk stratification of patients with PFO based on clinical or echocardiographic findings is not yet possible. The presence of atrial septal aneurysm, a wide opening of the defect during the cardiac cycle and a large atrial shunt have been implicated as risk factors by some investigators. Long-term prevention of paradoxical embolism with oral anticoagulants seems to be of questionable benefit. Besides, these agents are poorly tolerated and carry the risk of significant or fatal bleeding at a rate of 2-5% per year. Surgery of the atrial septum has been performed for many decades in patients with atrial septal defect and evidence accumulates that it is a safe and highly effective procedure in patients with PFO. At present, surgical closure of the PFO appears to be the treatment of choice for secondary prevention of paradoxical embolism. However, further studies are needed to define the appropriate candidates for surgical treatment. Devices for catheter-based sealing of PFO are also available and are currently being evaluated in clinical trials. However, experience with their use remains confined to specialized centers. Furthermore, further technical improvements of these systems are needed in order to optimize successful delivery and positioning, increase their long-term stability, and reduce periprocedural complications.

3D assessment of myocardial perfusion parameter combined with 3D reconstructed coronary artery tree from digital coronary angiograms

In patients with coronary artery disease coronary angiography plays an important role in the clinical decision-making process. However, it has been recognized that no simple relation exists between the visually or quantitatively evaluated severity of coronary artery stenoses and its effects on regional myocardial perfusion. This paper describes for the first time the development and application of a 3D technique that visualizes and quantifies regional myocardial perfusion parameters from biplane coronary angiograms by using the impulse response analysis technique. The 3D reconstructed coronary tree is automatically superimposed on the 3D perfusion image to generate and visualize an 'integrated' 3D image. The preliminary results in patients with critical coronary artery stenoses indicate that our combined 3D fusion image provides flow information from the major coronary arteries. This 3D fusion image may provide useful information in the management of patients with coronary artery disease.

Functional diversity of LAP2alpha and LAP2beta in postmitotic chromosome association is caused by an alpha-specific nuclear targeting domain

Lamina-associated polypeptide 2alpha (LAP2alpha) is a non-membrane-bound isoform of the LAP2 family implicated in nuclear structure organization. We show that during postmitotic nuclear assembly LAP2alpha associates with chromosomes prior to accumulation of the membrane-bound isoform LAP2beta, although both proteins contain the same putative chromatin interaction domains located in their common N-terminal regions. By transient and stable expression of various N- and C-terminal LAP2alpha deletion mutants in HeLa cells, we identified an approximately 350-amino-acid-long region in the C-terminal alpha-specific domain of the protein that is required for retention of LAP2alpha in interphase nuclei and for association with mitotic chromosomes, while the N-terminal domain seemed to be dispensable for these interactions. In vitro chromosome binding studies using recombinant LAP2alpha mutants revealed that this LAP2alpha-specific 'nuclear targeting domain' was essential and sufficient for association with chromosomes. These data suggested a functional diversity of chromosome binding properties of LAP2 isoforms.

Vitamin C improves endothelial function of epicardial coronary arteries in patients with hypercholesterolaemia or essential hypertension--assessed by cold pressor testing

AIMS

There is evidence that formation of free radicals increases in patients with hypertension or hypercholesterolaemia, which may contribute to endothelial dysfunction of epicardial coronary arteries due to inactivation of the vasodilator NO. The present study was designed to test whether the abnormal constriction of epicardial coronary arteries due to sympathetic stimulation by the cold pressor test in patients with essential hypertension or hypercholesterolaemia could be reversed by administration of the antioxidant vitamin C.

METHODS AND RESULTS

In 28 patients without relevant coronary artery stenosis the cold pressor test was performed before and after a 3 g infusion of vitamin C. In five normal controls the cold pressor test led to a similar increase in luminal area before and after vitamin C (3.7+/-1.3% and 1.9+/-0.8%, ns vs before vitamin C). In nine hypercholesterolaemic patients the cold pressor test led to a -14.1+/-2.8% reduction in cross-sectional area before vitamin C. This constriction was significantly improved after vitamin C to -7.6%+/-2.0, P=0.027 vs before vitamin C. In nine hypertensive patients, the cold pressor test led to a -17.1+/-3.2% decrease in cross-sectional area before vitamin C, which was improved to -7.1+/-3.1 after vitamin C, P=0.004 vs before vitamin C. This increase in luminal area was significant in each group in comparison with normal controls (each P<0.05). Administration of saline (placebo group, five patients) had no significant effect on cold pressor test-induced constriction (-6.9+/-3.9% before and -6. 8+/-3.7% after saline).

CONCLUSION

The antioxidant vitamin C reverses cold pressor test-induced vasoconstriction of epicardial coronary arteries in patients with hypertension or hypercholesterolaemia. Our data suggest that enhanced oxidative stress contributes to impaired endothelial function in this patient population.

Fusion imaging: combined visualization of 3D reconstructed coronary artery tree and 3D myocardial scintigraphic image in coronary artery disease

BACKGROUND

In patients with coronary artery disease, coronary angiography is performed for assessment of epicardial coronary artery stenoses. In addition, myocardial scintigraphy is commonly used to evaluate regional myocardial perfusion. These two-dimensional (2D) imaging modalities are typically reviewed through a subjective, visual observation by a physician. Even though on the analysis of 2D display scintigraphic myocardial perfusion segments are arbitrarily assigned to three major coronary artery systems, the standard myocardial distribution territories of the coronary tree correspond only in 50-60% of patients. On the other hand, the mental integration of both 2D images of coronary angiography and myocardial scintigraphy does not allow an accurate assignment of particular myocardial perfusion regions to the corresponding vessels. To achieve an objective assignment of each vessel segment of the coronary artery tree to the corresponding myocardial regions, we have developed a 3D 'fusion image' technique and applied it to patients with coronary artery disease. The morphological data (coronary angiography) and perfusion data (myocardial scintigraphy) are displayed in a 3D format, and these two 3D data sets are merged into one 3D image.

RESULTS

Seventy-eight patients with coronary artery disease were studied with this new 3D fusion technique. Of 162 significant coronary lesions, 120 (74%) showed good coincidence with regional myocardial perfusion abnormality on 3D fusion image. No regional myocardial perfusion abnormality was found in 44 (26%) lesions. Furthermore, the 3D fusion image revealed 24 ischemic myocardial regions that could not be related to angiographically significant coronary artery lesions.

CONCLUSION

The results of this study demonstrate that our newly developed 3D fusion technique is useful for an accurate assignment of coronary vessel segments to the corresponding myocardial perfusion regions, and suggest that it may be helpful to improve the interpretative and decision-making process in the treatment of patients with coronary artery disease.

Haemodynamic effects of intracoronary pyruvate in patients with congestive heart failure: an open study

BACKGROUND

Pyruvate, as an intermediate in the Krebs cycle, is an important source of energy for myocardium and improves contractility of normal, hypoxic, and postischaemic animal myocardium. We investigated the effect of intracoronary pyruvate in patients with congestive heart failure.

METHODS

Haemodynamic measurements were done in eight patients with dilated cardiomyopathy after two 15 min infusions of pyruvate into the left main coronary artery and after saline washout of pyruvate.

FINDINGS

There were no significant differences between the two pyruvate concentrations. Application of pyruvate resulted in a 23% increase in cardiac index (p<0.05), a 38% increase in stroke-volume index (p<0.05), and a 36% decrease in pulmonary capillary wedge pressure (p<0.05). Heart rate decreased significantly by 11%. Mean aortic pressure and systemic vascular resistance did not change. Most of the effects of pyruvate were reversed 15 min after the infusion stopped.

INTERPRETATION

Pyruvate has the profile of a favourable inotropic substance. Other modes of administration need to be studied.

Functional effects of endothelin and regulation of endothelin receptors in isolated human nonfailing and failing myocardium

BACKGROUND

An activated endothelin (ET) system may be of pathophysiological relevance in human heart failure. We characterized the functional effects of ET-1, ET receptors, and ET-1 peptide concentration in left ventricular myocardium from 10 nonfailing hearts (NF) and 27 hearts in end-stage failure due to idiopathic dilative cardiomyopathy (DCM).

METHODS AND RESULTS

Inotropic effects were characterized in isolated muscle strips (1 Hz; 37 degrees C). ET-1 0.0001 to 0.3 micromol/L significantly (P<0.05) increased twitch force by maximally 59+/-10% in NF and by 36+/-11% in DCM (P<0.05 versus NF). Preincubation with propranolol 1 micromol/L and prazosin 0.1 micromol/L did not affect the response to ET-1, but the mixed ET receptor antagonist bosentan and the ETA receptor antagonist BQ-123 shifted the concentration-response curves for ET-1 rightward. The ETB receptor agonist sarafotoxin S6c 0.001 to 0.3 micromol/L had no functional effects. The inotropic response to ET-1 was not associated with increased intracellular Ca2+ transients, as assessed in aequorin-loaded muscle strips. ET receptor density (Bmax; radioligand binding) was 62.5+/-12.5 fmol/mg protein in NF and 122. 4+/-24.3 fmol/mg protein in DCM (P<0.05 versus NF). The increase in Bmax in DCM resulted from an increase in ETA receptors without change in ETB receptors. ET-1 peptide concentration (radioimmunoassay) was higher in DCM than in NF (14 447+/-2232 versus 4541+/-1340 pg/mg protein, P<0.05).

CONCLUSIONS

ET-1 exerts inotropic effects in human myocardium through ETA receptor-mediated increases in myofibrillar Ca2+ responsiveness. In DCM, functional effects of ET-1 are attenuated, but ETA receptor density and ET-1 peptide concentration are increased, indicating an activated local cardiac ET system and possibly a reduced postreceptor signaling efficiency.

Relationship between Na+-Ca2+-exchanger protein levels and diastolic function of failing human myocardium

BACKGROUND

In the failing human heart, sarcoplasmic reticulum (SR) calcium handling is impaired, and therefore, calcium elimination and diastolic function may depend on the expression of sarcolemmal Na+-Ca2+ exchanger.

METHODS AND RESULTS

Force-frequency relations were studied in ventricular muscle strip preparations from failing human hearts (n=29). Protein levels of Na+-Ca2+ exchanger and SR Ca2+-ATPase were measured in the same hearts. Hearts were divided into 3 groups by discriminant analysis according to the behavior of diastolic function when stimulation rate of muscle strips was increased from 30 to 180 min-1. At 180 compared with 30 min-1, diastolic force was increased by 160%, maximum rate of force decline was decreased by 46%, and relaxation time was unchanged in group III. In contrast, in group I, diastolic force and maximum rate of force decline did not change, and relaxation time decreased by 20%. Na+-Ca2+ exchanger was 66% higher in group I than in group III. Na+-Ca2+ exchanger was inversely correlated with the frequency-dependent rise of diastolic force when stimulation rate was increased (r=-0.74; P<0.001). Compared with nonfailing human hearts (n=6), SR Ca2+-ATPase was decreased and Na+-Ca2+ exchanger unchanged in group III, whereas Na+-Ca2+ exchanger was increased and SR Ca2+-ATPase unchanged in group I. Results with group II hearts were between those of group I and group III hearts.

CONCLUSIONS

By discriminating failing human hearts according to their diastolic function, we identified different phenotypes. Disturbed diastolic function occurs in hearts with decreased SR Ca2+-ATPase and unchanged Na+-Ca2+ exchanger, whereas increased expression of the Na+-Ca2+ exchanger is associated with preserved diastolic function.

Influence of forskolin on the force-frequency behavior in nonfailing and end-stage failing human myocardium

End-stage failing human myocardium is characterized by a negative force-frequency relationship (FFR), possibly as a result of reduced SR Ca2+ uptake capacity. We investigated the effects of the direct adenylate cyclase stimulator, forskolin, on force of contraction and FFR in isolated human myocardium from 7 nonfailing hearts (NF) and end-stage failing hearts (NYHA IV) due to either ischemic (ICM; n = 13) or dilated cardiomyopathy (DCM; n = 16).

METHODS

Isolated left ventricular muscle strips, isometric contraction, electrical stimulation at a basal stimulation rate of 1 Hz (37 degrees C). Inotropic responses: Cumulative concentration-response curves for forskolin (0.01-10 microM) and for Ca2+ (2.5-15 mM). Force-frequency experiments: stepwise increase in stimulation rate from 0.5 to 3.0 Hz without and in the presence of 0.3, 1.0 or 3.0 microM forskolin.

RESULTS

Forskolin concentration-dependently increased force of contraction to 386 +/- 28% (n = 5) in NF, to 256 +/- 48% (n = 7) in ICM, and to 212 +/- 13% (n = 14) in DCM. The effectiveness of forskolin was significantly reduced in failing myocardium. Ca2+ increased force of contraction to maximally 438 +/- 108% in NF, to 267 +/- 15% in ICM, and to 292 +/- 20% in DCM. Again, the effectiveness of Ca2+ was significantly reduced in failing myocardium. Forskolin activated contractile reserve to similar extents in all types of myocardium (90%, 95%, and 82%, respectively). Force of contraction continuously increased with increasing stimulation rates in nonfailing myocardium (positive FFR), but was blunted or inversed in ICM and DCM. Prestimulation with forskolin (0.3 microM) further enhanced frequency-potentiation in nonfailing, and normalized the slope and optimum stimulation frequency in ICM and DCM. However, at higher concentrations of forskolin, FFR was blunted or inversed in non-failing myocardium, and further impaired in failing myocardium.

CONCLUSION

Low concentrations of forskolin with only marginal inotropic effects may partially normalize the inverse force-frequency relation in end-stage failing human myocardium. Reduced cAMP levels in conjunction with reduced expression of SR Ca2+ ATPase may be the underlying cause for altered excitation-contraction coupling in diseased human hearts.

Influence of SR Ca(2+)-ATPase and Na(+)-Ca(2+)-exchanger on the force-frequency relation

The data presented indicate that altered systolic and diastolic function in failing human hearts may result from altered expression of calcium cycling proteins. Decreased systolic force production and inversion of the force-frequency relation seem to be related to reduced protein levels of SR Ca2+ ATPase and/or to increased protein levels of the Na(+)-Ca2+ exchanger resulting in an increased ratio of Na(+)-Ca2+ exchanger to SR Ca2+ ATPase. Impaired diastolic function may result from reduced SR Ca2+ ATPase and is most pronounced in failing hearts with lack of upregulation of the Na(+)-Ca2+ exchanger. Thus, failing hearts with reduced SR Ca2+ ATPase protein levels and unchanged Na(+)-Ca2+ exchanger protein levels exhibit severe impairment of both systolic and diastolic function.

Alterations of cross-bridge kinetics in human atrial and ventricular myocardium

CONDENSED ABSTRACT

We analyzed actomyosin cross-bridge kinetics in human atrial and ventricular muscle strip preparations by using sinusoidal length changes from 0.1 to 60 Hz. The minimum stiffness frequency was higher in atrial than in ventricular human myocardium and lower in failing than in non-failing left ventricular human myocardium. beta-Adrenergic stimulation increased the minimum stiffness frequency by 18 +/- 3% (p < 0.05). Cross-bridge kinetics are temperature-dependent, with a Q10 of at least 2.7.

BACKGROUND

Dynamic stiffness measurements have revealed acute and chronic alterations of actomyosin cross-bridge kinetics in cardiac muscles of a variety of different animal species. We studied dynamic stiffness in right atrial and left ventricular preparations of non-failing and failing human hearts and tested the influence of the temperature and beta-adrenergic stimulation on cross-bridge kinetics.

METHODS AND RESULTS

Muscle strips were prepared from right atria and left ventricles from human non-failing and failing hearts. After withdrawal of calcium, steady contracture tension was induced by the addition of 1.5 mM barium chloride. Sinusoidal length oscillations of 1% muscle length were applied, with a frequency spectrum of between 0.1 and 60 Hz. Dynamic stiffness was calculated from the length change and the corresponding force response amplitude. The specific minimum stiffness frequency, which indicates the interaction between cross-bridge recruitment and cross-bridge cycling dynamics, was analyzed for each condition: (1) The minimum stiffness frequency was 0.78 +/- 0.04 Hz in left ventricular myocardium and 2.80 +/- 0.31 Hz in right atrial myocardium (p < 0.01) at 27 degrees C. (2) The minimum stiffness frequency was 41% higher in non-failing compared to failing left ventricular human myocardium. (3) Over a wide range of experimental temperatures, the minimum stiffness frequency changed, with a Q10 of at least 2.7. (4) beta-Adrenergic stimulation significantly (p < 0.05) increased the minimum stiffness to 18 +/- 3% higher frequencies and significantly (p < 0.05) lowered contracture tension by 7 +/- 1%.

CONCLUSIONS

The contractility of human heart muscle is not only regulated by excitation-contraction coupling but also by modulation of intrinsic properties of the actomyosin system. Acute and chronic alterations of cross-bridge kinetics have been demonstrated, which play a significant role in the physiology and pathophysiology of the human heart.

Cardiac and hemodynamic effects of the sinus node inhibitor tedisamil dihydrochloride in patients with congestive heart failure due to dilated cardiomyopathy

Clinical and experimental investigations have demonstrated an inverse relation between heart rate and myocardial performance in patients with congestive heart failure. Accordingly, this study was designed to investigate the hemodynamic effect of the novel bradycardic compound tedisamil in patients with heart failure. We hypothesized that tedisamil would reduce heart rate and thereby improve hemodynamic parameters of failing hearts with an inverse force-frequency relation. Tedisamil was administered intravenously in nine patients with dilated cardiomyopathy (NYHA II-III). Hemodynamic measurements by right heart catheterization were carried out at time points -30, 10, 20 min, 1, 2, 4, and 6 h. Tedisamil decreased heart rate significantly from 84 +/- 6 beats/min to 73 +/- 4 beats/min (at 10 min; p < 0.05). Stroke volume index remained unchanged, and cardiac index tended to decrease transiently. Mean blood pressure increased from 98 +/- 5 to 104 +/- 6 mm Hg (p < 0.05) because of an increase in systemic vascular resistance from 1,619 +/- 145 to 2,079 +/- 198 dyn x s x cm(-5) (at 20 min; p < 0.05). Diastolic pulmonary pressure and pulmonary vascular resistance showed similar changes. Pulmonary capillary wedge pressure increased from 12 +/- 3 to 16 +/- 4 mm Hg (at 20 min; p < 0.05). Although tedisamil resulted in a significant heart-rate reduction, this was not associated with an improvement of hemodynamics. This may be due to increased afterload of the left and right ventricle. In these patients, tedisamil increased vascular resistance, which is unwanted in the treatment of congestive heart failure.

Influence of the novel inotropic agent levosimendan on isometric tension and calcium cycling in failing human myocardium

BACKGROUND

Levosimendan was shown to increase calcium sensitivity by a novel mechanism and to inhibit phosphodiesterase III activity in animal myocardium.

METHODS AND RESULTS

We investigated the influence of levosimendan on isometric contractions and calcium transients (aequorin method) in muscle strips from human hearts with end-stage failing dilated or ischemic cardiomyopathy (n=27). Data were compared with the effects of the phosphodiesterase inhibitor milrinone (n=9). The average maximum increase in twitch tension was 47+/-14% (range, 6% to 150%) at a levosimendan concentration of 0. 8+/-0.3 micromol/L (P<0.01). This was associated with significant increases in maximum rates of tension rise and fall and decreases in times to peak tension, to 50% relaxation, and to 95% relaxation. In aequorin-loaded muscles, levosimendan 10(-6) mol/L increased average tension by 50% (P<0.02), associated with a nonsignificant increase in aequorin light (16%). With milrinone 10(-5) mol/L, average tension increased by 58% and aequorin light by 49% (P<0.05). In those muscle strips with pronounced inotropic effects (>50% increase in tension), there was a comparable and pronounced increase in aequorin light with both agents. However, in muscle strips with weak inotropic responses (<50% increase in tension), the increase in light was significantly higher with milrinone than with levosimendan.

CONCLUSIONS

Levosimendan has inotropic and lusitropic actions in failing human myocardium. Comparison with the phosphodiesterase inhibitor milrinone indicates that in case of pronounced inotropic stimulation, the modes of action of the two agents may be similar (phosphodiesterase inhibition), whereas small inotropic effects of levosimendan may result predominantly from calcium sensitization.

Comparison of alteplase versus heparin for resolution of major pulmonary embolism

Complete resolution of major pulmonary embolism (PE) treated with heparin alone can often take > 3 weeks. Thrombolytic agents effectively resolve pulmonary artery thrombi within a few hours. However, the effect of the 2 types of treatment on recovery of right ventricular function has not yet been followed for periods of > 24 hours. We prospectively examined 40 consecutive patients with documented major PE (symptoms being present for < or = 8 weeks). After diagnosis, 27 patients (68%) were treated with alteplase plus heparin and 13 (32%) with heparin alone. There was no significant difference between the 2 groups with regard to baseline parameters. At 12 hours, systolic pulmonary artery pressure decreased from 56 +/- 20 to 37 +/- 21 mm Hg in the alteplase group, and from 50 +/- 11 to 46 +/- 12 mm Hg in the heparin group (significantly more; p = 0.016). On echocardiographic follow-up, a decrease in end-diastolic dimensions of the right ventricle and an increase in left ventricular dimensions was significantly more pronounced in the alteplase group (p <0.001 and p = 0.05, respectively). The incidence of right ventricular dilation and paradoxical septal wall motion decreased significantly only in the thrombolyis group. However, at 1-week follow-up, no difference was seen between the 2 groups regarding the overall change in right or left ventricular dimensions or the final values of other echocardiographic parameters. Thus, echocardiography is particularly useful for hemodynamic follow-up of major PE. Thrombolysis may rapidly reduce pulmonary artery pressure, but resolution of right ventricular pressure overload also occurs within 1 week in patients treated with heparin alone.

Sarcoplasmic reticulum proteins in heart failure

Altered calcium homeostasis may play a key role in the pathophysiology of human heart failure. Levels of sarcoplasmic reticulum (SR) proteins and sarcolemmal Na(+)-Ca2+ exchanger were analyzed by Western blot in failing and nonfailing human myocardium and related to myocardial function. Levels of the SR calcium release channel and of calcium storage proteins (calsequestrin and calreticulin) were not different in nonfailing and failing hearts. However, proteins involved in calcium removal were significantly altered in the failing human heart: (1) SR-Ca(2+)-ATPase levels and the ratio of SR-Ca(2+)-ATPase to its inhibitory protein phospholamban were significantly decreased, and (2) Na(+)-Ca2+ exchanger levels and the ratio of Na(+)-Ca2+ exchanger to SR-Ca(2+)-ATPase were significantly increased. SR-Ca(2+)-ATPase levels were closely correlated to systolic function as evaluated by frequency potentiation of contractile force. The frequency-dependent rise of diastolic force was inversely correlated with protein levels of Na(+)-Ca2+ exchanger. These findings indicate that altered expression of SR-Ca(2+)-ATPase and Na(+)-Ca2+ exchanger is relevant for altered systolic and diastolic function in human heart failure.

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.

Frequency-dependent changes in contribution of SR Ca2+ to Ca2+ transients in failing human myocardium assessed with ryanodine

We tested the influence of blocking sarcoplasmic reticulum (SR) function with ryanodine (1 microM) on stimulation rate-dependent changes of intracellular Ca2+ transients and twitch force in failing human myocardium. Isometrically contracting, electrically stimulated muscle strips from ventricles of 10 end-stage failing human hearts were used. Muscles were loaded with the intracellular Ca2+ indicator aequorin. At stimulation rates from 0.5-3 Hz, intracellular Ca2+ transients and twitch force were simultaneously recorded before and after ryanodine exposure (37 degrees C). Ryanodine significantly reduced twitch force at 1 Hz by 46 +/- 9% and aequorin light by 57 +/- 10% in failing human myocardium (P < 0.05). The blunted or inverse aequorin light- and force-frequency relation became positive after ryanodine: in failing human myocardium, twitch force and aequorin light before ryanodine did not increase with increasing frequency and force decreased significantly at 3 Hz (P < 0.05). After ryanodine, twitch force (P < 0.05) and aequorin light increased with increasing stimulation frequency and were maximum at 2 Hz. The data indicate that inhibition of SR function significantly reduces twitch force and Ca2+ transients in failing human myocardium, but converts the blunted or inverse Ca(2+)- and force-frequency relation into a positive one. We infer that Ca2+ responsible for approximately 50% of twitch force is derived from the SR and approximately 50% from sarcolemmal Ca2+ influx in failing human myocardium. This sarcolemmal component increases at higher stimulation frequencies.

Patent foramen ovale is an important predictor of adverse outcome in patients with major pulmonary embolism

BACKGROUND

Right-to-left shunt through a patent foramen ovale is frequently diagnosed by contrast echocardiography and can be particularly prominent in the presence of elevated pressures in the right side of the heart. Its prognostic significance in patients with pulmonary thromboembolism, however, is unknown.

METHODS AND RESULTS

The present prospective study included 139 consecutive patients with major pulmonary embolism diagnosed on the basis of clinical, echocardiographic, and cardiac catheterization criteria. All patients underwent contrast echocardiography at presentation. The end points of the study were overall mortality and complicated clinical course during the hospital stay defined as death, cerebral or peripheral arterial thromboembolism, major bleeding, or need for endotracheal intubation or cardiopulmonary resuscitation. Patent foramen ovale was diagnosed in 48 patients (35%). These patients had a death rate of 33% as opposed to 14% in patients with a negative echo-contrast examination (P=.015). Logistic regression analysis demonstrated that the only independent predictors of mortality in the study population were a patent foramen ovale (odds ratio [OR], 11.4; P<.001) and arterial hypotension at presentation (OR, 26.3; P<.001). Patients with a patent foramen ovale also had a significantly higher incidence of ischemic stroke (13% versus 2.2%; P=.02) and peripheral arterial embolism (15 versus 0%; P<.001). Overall, the risk of a complicated in-hospital course was 5.2 times higher in this patient group (P<.001).

CONCLUSIONS

In patients with major pulmonary embolism, echocardiographic detection of a patent foramen ovale signifies a particularly high risk of death and arterial thromboembolic complications.

The trabecula culture system: a novel technique to study contractile parameters over a multiday time period

In the intact heart, various triggers induce alterations in gene expression that impact on contractile function. Because changes in gene expression reflect altered protein expression patterns after 12-48 h, we developed a system in which intact twitching cardiac trabeculae can be studied for multiday periods. Right ventricular trabeculae from pentobarbital sodium anesthetized rabbits were mounted in a sterile, closed muscle chamber. Over the first 48 h, developed force (Fdev) did not significantly change: 102.3 and 98.9% of the initial Fdev was observed after 24 and 48 h, respectively (n = 8). Also, neither diastolic force, time from peak to 50% relaxation (RT50), nor protein synthesis measured by a [3H]leucine incorporation assay changed significantly over time. Contractile response after > 48 h to an increase in extracellular calcium concentration (1.8 to 2.5 mM; Fdev increased 43.5%, n = 2) or to 1 microM isoproterenol (Fdev increased 138.6% and RT50 decreased 34.9%, n = 2) was similar to those observed in freshly dissected preparations. In conclusion, this system can investigate contractile function of multicellular preparations under well-defined physiological conditions after events that alter gene and consequent protein expression.

[Bypass perforation by stent implantation: complication management. A case report]

We describe a case-report on an perforation of an aorto-coronary venous bypass graft, a complication induced by a stent-implantation. Perforations of coronary arteries are rare, however, for interventional cardiologists well-known complications. This case report is of special interest (1) because the perforation did not occur in a coronary artery but rather in an eight year old venous bypass graft and (2) because the perforation was induced by a stent-implantation. In addition, this case report describes in great detail the management of vessel perforation: several invasive methods contributed to minimize pericardial effusion and to stabilize the patient until surgical revision could be performed.

[Effect of nitrates on arterial blood vessels exemplified by the radial artery]

Nitrates act, in part, by causing systemic venodilation. In addition, nitrates lead to dilation of arterial conductance vessels. The maximal dilation capacity and threshold of arterial conductance vessels have so far not been examined thoroughly. Therefore, we tested the radial artery diameter before and after i.v. nitroglycerin infusions at increasing dosages (0.015, 0.05, 0.15, 0.5, and 1.5 micrograms/kg/min), 7 min each dose in 28 patients with suspected coronary artery disease (mean age +/- SEM 58 +/- 2 years) using a high resolution ultrasound devise. The low doses of 0.05 and 0.15 microgram/kg/min, equal to dose of 2.5 mg/12 hours and 7.5 mg/12 hours in a patient with 70 kg, led to substantial increases in the cross sectional luminal area of the radial artery of 14.8 +/- 1.5% and 29.3 +/- 2.2%*, (*p < 0.05 vs baseline). The maximal increase (dilatory capacity) was 53.8 +/- 3.8% (mean diameter at baseline: 2.7 +/- 0.1 mm, maximal 3.4 +/- 0.1 mm, p < 0.001). The nitrate sensitivity of the radial artery was estimated by calculation of the ED50, the dose that caused half-maximal dilation of the radial artery. The ED50 of the radial artery was 0.13 +/- 0.003 microgram/kg/min. In conclusion, nitroglycerin leads to a dose dependent dilatation of peripheral conductance vessels. Low doses of 0.05 and 0.15 microgram/kg/min lead to significant arterial dilation. The maximal dilatory capacity of the radial artery is 53.8 +/- 3.5%.

Long-term nitroglycerin treatment is associated with supersensitivity to vasoconstrictors in men with stable coronary artery disease: prevention by concomitant treatment with captopril

OBJECTIVES

We examined whether long-term nitroglycerin (NTG) treatment leads to an increase in sensitivity to vasoconstrictors. To assess a potential role of the renin-angiotensin system in mediating this phenomenon, we treated patients concomitantly with the angiotensin-converting enzyme (ACE) inhibitor captopril.

BACKGROUND

The anti-ischemic efficacy of organic nitrates is rapidly blunted by the development of nitrate tolerance. The underlying mechanisms are most likely multifactorial and may involve increased vasoconstrictor responsiveness.

METHODS

Forearm blood flow and vascular resistance were determined by using strain gauge plethysmography. The short-term responses to intraarterial angiotensin II (1, 3, 9 and 27 ng/min) and phenylephrine (an alpha-adrenergic agonist drug, 0.03, 0.1, 0.3 and 1 microg/min) were studied in 40 male patients with stable coronary artery disease. These patients were randomized into four groups receiving 48 h of treatment with NTG (0.5 microg/kg body weight per min) or placebo with or without the ACE inhibitor captopril (25 mg three times daily).

RESULTS

In patients treated with NTG alone, the maximal reductions in forearm blood flow in response to angiotensin II and phenylephrine were markedly greater (-64 +/- 3% and -53 +/- 4%, respectively) than those in patients receiving placebo (-41 +/- 2% and -42 +/- 2%, respectively). Captopril treatment completely prevented the NTG-induced hypersensitivity to angiotensin II and phenylephrine (-33 +/- 3% and -35 +/- 3%, respectively) but had no significant effect on blood flow responses in patients without NTG treatment (-34 +/- 2% and -37 +/- 3%, respectively).

CONCLUSIONS

We conclude that continuous administration of NTG is associated with an increased sensitivity to phenylephrine and angiotensin II that is prevented by concomitant treatment with captopril. The prevention of NTG-induced hypersensitivity to vasoconstrictors by ACE inhibition indicates an involvement of the renin-angiotensin system in mediating this phenomenon.

Shortening versus isometric contractions in isolated human failing and non-failing left ventricular myocardium: dependency of external work and force on muscle length, heart rate and inotropic stimulation

BACKGROUND

For reasons of simplicity, studies on isolated human myocardium have been conducted using exclusively isometric contractions, although positive inotropic interventions may differently influence force development, extent of shortening and myocardial work performance. We investigated human left ventricular failing and non-failing preparations comparing isometric versus isotonic, i.e., shortening contractions.

RESULTS

(1) When muscle length is increased from 90% to 100% lMAX, peak developed force increases by 36% and 43% (p < 0.05) in non-failing and failing human left ventricular myocardium, respectively. Maximum performed work increases similarly in non-failing but decreases in failing myocardium. It can be shown that this discrepancy is due to significantly higher resting tension and does not present an insufficient intrinsic shortening capacity in failing myocardium. (2) When stimulation rate is increased from 0.5 to 2.0 Hz, isometric force increases significantly by 59% in non-failing and decreases by 27% in failing myocardium, whereas maximum performed work increases by 98% and decreases by 46%, respectively. (3) Pharmacological positive inotropic interventions by 7.2 mM calcium (n = 9), 3 x 10(-8) M isoproterenol (n = 7), 3 x 10(-8) M ouabain (n = 5), and 10(-5) M EMD 57033 (n = 3) equally increased force development and extent of shortening: When the fractional effect on shortening (y) was correlated to the fractional effect on force (x), the following linear regression equation was obtained: y = 0.91x + 0.26 (r = 0.86; p < 0.001).

CONCLUSIONS

The data presented are of clinical and pharmacological importance: (1) The Frank-Starling mechanism is demonstrated to be existent in the failing human myocardium regarding both isometric force developed and maximum work performed. (2) Both force-frequency relations and--to a greater extent--work-frequency relations are reversed in failing human myocardium. (3) Independent of the pharmacological mode of action, positive inotropic compounds increase developed isometric force to the same extent as isotonic shortening and therefore potentiate maximum performed work.

Enhancement of platelet inhibition of ticlopidine plus aspirin vs aspirin alone given prior to elective PTCA

BACKGROUND

In many patients today, elective percutaneous transluminal coronary angioplasty is followed by implantation of coronary stents to achieve optimal results. The current medical strategy to prevent early reocclusion is the inhibition of platelet aggregation by administration of ticlopidine, in addition to aspirin, immediately after the procedure. In order to inhibit platelet aggregation as early as possible, many centres begin to treat patients with additional ticlopidine the day before elective coronary intervention. The aim of this study was to determine the effect of this strategy on platelet aggregation before angioplasty.

METHOD

Fifty-two consecutive patients admitted to hospital for elective balloon angioplasty were prospectively randomized to receive either standard oral aspirin 100 mg per day or standard therapy plus 250 mg ticlopidine at the time of admission and the morning before angioplasty. Adenosine diphosphate-, collagen- and epinephrine-induced platelet aggregation was measured immediately before the procedure by an investigator who was blinded concerning the arm of therapy.

RESULTS

The two groups of patients were comparable in terms of age, sex, body mass index, anginal state, time interval between application of study drug and coronary intervention. Patients on aspirin and ticlopidine had a mean maximal platelet aggregation of 36 +/- 12% with adenosine diphosphate as agonist. For the control group, 54 +/- 12% was measured (P < 0.001). Myocardial infarction or emergency coronary bypass grafting did not occur in either group. Local haemorrhagic complications at the arterial access site occurred in five (aspirin) and six (aspirin and ticlopidine) patients (P = ns) none of them requiring blood transfusion.

CONCLUSION

The additional application of ticlopidine to chronic aspirin therapy the day before elective coronary balloon angioplasty leads to a significantly higher inhibition of platelet aggregation at the time of the intervention. It seems to be safe compared to the standard procedure.

Vitamin C improves endothelial dysfunction of epicardial coronary arteries in hypertensive patients

BACKGROUND

There is evidence for increased formation of free radicals in patients with hypertension, raising the possibility that NO is inactivated by free radicals, which impairs coronary endothelial function. Therefore, we tested the hypothesis that the antioxidant vitamin C could improve abnormal endothelial function of coronary arteries in patients with hypertension.

METHODS AND RESULTS

In 22 hypertensive patients without relevant coronary artery stenoses, endothelium-dependent vascular responses of the left anterior descending coronary artery (LAD) to acetylcholine (0.01, 0.1, and 1.0 micromol/L) were determined before and immediately after intravenous infusion of 3 g vitamin C (17 patients) or placebo (5 patients). In a subgroup of 10 patients, papaverine-induced flow-dependent vasodilation (FDD) was measured before and after vitamin C (5 patients) or placebo (5 patients) infusion. Segmental responses of the coronary artery luminal area were analyzed with quantitative coronary angiography. Before vitamin C infusion, the mean changes of LAD luminal areas at increasing doses of acetylcholine were -6.1+/-2.2%, -15.2+/-4.9%, and -33.9+/-8.1% (negative numbers symbolize vasoconstriction) and during FDD, 5.4+/-1.0%. The vasoconstrictor response during acetylcholine was reduced and FDD was augmented by vitamin C. After vitamin C infusion, LAD luminal areas changed by -3.2+/-2.3%, -5.8+/-3.6%, and -10.2+/-5.6% (P<.05, acetylcholine) and 17.8+/-2.8% (P<.05, FDD). Doppler flow velocity (during baseline, acetylcholine, and FDD) was not significantly affected by vitamin C.

CONCLUSIONS

Vitamin C improves the endothelium-dependent vasomotor capacity of coronary arteries in patients with hypertension and patent coronary arteries. These findings suggest that increased oxidative stress contributes to endothelial dysfunction in hypertensive patients.

Association between thrombolytic treatment and the prognosis of hemodynamically stable patients with major pulmonary embolism: results of a multicenter registry

BACKGROUND

Thrombolytic treatment has been shown to accelerate resolution of major pulmonary embolism and lead to a rapid improvement of right-side hemodynamics. However, the association between these favorable effects and the clinical outcome of patients who have no severe hemodynamic compromise at presentation remains unknown.

METHODS AND RESULTS

The present multicenter registry included 719 consecutive patients with major pulmonary embolism according to clinical, echocardiographic, scintigraphic, and cardiac catheterization criteria. Symptom onset was acute (<48 hours) in 63% of patients. All patients were hemodynamically stable (ie, without evidence of cardiogenic shock) at presentation. Primary thrombolytic treatment (within 24 hours of diagnosis) was given to 169 patients (23.5%), whereas the remaining 550 patients were initially treated with heparin alone. Overall 30-day mortality was significantly lower in the patients who received thrombolytic agents (4.7 versus 11.1%, P=.016). Clinical factors associated with a higher death rate were syncope (P=.012), arterial hypotension (P=.021), history of congestive heart failure (P=.013), and chronic pulmonary disease (P=.032). However, only primary thrombolysis was found by multivariate analysis to be an independent predictor of survival (odds ratio for in-hospital death, 0.46; 95% confidence interval, 0.21 to 1.00). Patients who underwent early thrombolytic treatment had a reduced rate of recurrent pulmonary embolism (7.7 versus 18.7%, P<.001) but also a higher frequency of major bleeding episodes (21.9% versus 7.8%, P<.001). Cerebral bleeding occurred in 2 patients in each treatment group, and 1 patient in each group died of a bleeding complication.

CONCLUSIONS

The results of our study suggest that thrombolysis may favorably affect the clinical outcome of hemodynamically stable patients with major pulmonary embolism.

["Myxoma syndrome"--a "benign" disease with "malignant" course]

We are reporting on a 36 year-old woman who presented with recurrent cardiac myxomas over a period of nine years. Two of the tumors typically originated in the left atrium and one in the right atrium. Tumor embolization was the presenting symptom twice, leading to reversible cerebral ischemia and minor pulmonary embolism, respectively. The third tumor remained asymptomatic and was detected during routine echocardiographic examination. Based on a positive family history of cardiac tumors, a facially pronounced hyperpigmentation of the skin and the presence of a thyroid adenoma, the diagnosis of a "myxoma syndrome" was established. Patients with "myxoma syndrome" are generally younger than their counterparts with "sporadic myxoma" (mean age at diagnosis 25 vs. 56 years) and have a high frequency of unusual skin freckling (68%). Familial clustering of cardiac myxomas is also frequent (25%). The tumors may be located in any of the cardiac chambers (87% in the atrias, 13% in the ventricles, 50% at multiple sites simultaneously) and have relatively high (18%) 5-year recurrence rate after surgical excision. Since the clinical signs of cardiac tumors are non-specific, diagnosis essentially relies on cardiac imaging by echocardiography, computer tomography, or angiography. The superiority of transesophageal echocardiography is emphasized in this report.

Noninvasive estimation of right ventricular systolic pressure in postinfarction ventricular septal rupture: an assessment of two Doppler echocardiographic methods

OBJECTIVE

To evaluate the diagnostic accuracy of Doppler echocardiography in the assessment of right heart hemodynamics and the diagnosis of pulmonary hypertension in patients with ventricular septal rupture due to acute myocardial infarction.

DESIGN

A prospective, echocardiographic and right-heart catheterization study.

SETTING

Medical intensive care unit (ICU) of a university hospital.

PATIENTS

Twelve consecutive patients admitted to the ICU with the diagnosis of ventricular septal rupture in the setting of acute myocardial infarction. Confirmation of diagnosis was made during surgery (11 patients) or by autopsy (one patient).

INTERVENTIONS

All patients were examined by two-dimensional and Doppler echocardiography on admission and subsequently underwent bedside right-heart catheterization.

MEASUREMENTS AND MAIN RESULTS

After identification and localization of the rupture site by two-dimensional echocardiography and/or color flow Doppler mapping, the maximal flow velocity of the transseptal jet was measured by continuous-wave Doppler and was used to calculate the peak interventricular pressure gradient by the modified Bernoulli equation. This value was subtracted from the systolic arterial blood pressure value to estimate right ventricular systolic pressure. The values obtained correlated well with catheter-derived measurements (r2 = .71; p = .001). Furthermore, in eight (67%) patients, right ventricular systolic pressure could also be determined by Doppler interrogation of the tricuspid regurgitant jet. Direct comparison of the results of the two echocardiographic methods yielded a good correlation (r2 = .66; p = .016).

CONCLUSION

Doppler examination of the transseptal and tricuspid regurgitant jets is applicable to patients with ventricular septal rupture for rapid, noninvasive prediction of right ventricular hemodynamics.

Differential cytokine production in stimulated blood cultures from intensive care patients with bacterial infections

Mice infected with bacteria develop an interferon-gamma (IFN-gamma) dependent hypersensitivity to lipopolysaccharide (LPS) and other bacterial components. The broader aim of this study is to find out whether such hypersensitivity also occurs in patients suffering from bacterial infections. The capacity of stimulated peripheral blood cells from infected, intensive-care patients to produce cytokines (IFN-gamma, tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6)) was compared to that of healthy donors. Culturing of the cells was carried out preferentially in whole blood diluted 1:3. Whole blood cultures (WBC) were stimulated with lipopolysaccharide (LPS), whole killed Salmonella typhimurium and Staphylococcus aureus and concanavalin A (ConA), and the cytokine production was determined. Two main findings emerged from this study: The IFN-gamma production by WBC of patients was, compared to healthy donors, markedly suppressed, regardless of stimulus used. Further, patients' WBC exhibited a suppressed TNF-alpha production after stimulation with LPS. Surprisingly, following stimulation with bacteria (S. typhimurium and S. aureus) an elevated TNF-alpha and IL-6 response was obtained. Thus, in severely infected patients the cytokine responses of peripheral blood cells to LPS may be suppressed, while the response to other bacterial components is enhanced.

[Magnesium deficiency and magnesium substitution. Effect on ventricular cardiac arrhythmias of various etiology]

During recent years there has been an increasing but still controversial discussion on the antiarrhythmic effects and overall benefit of magnesium when directed to patients with various types of ventricular tachyarrhythmias. While magnesium is considered to be a simple, safe and cost-effective approach and many casuistic and empiric reports have indicated antiarrhythmic properties of magnesium in patients with suspected or manifest ventricular arrhythmias, controlled studies proving the antiarrhythmic and overall benefit and justifying a broader use of magnesium in treating various types of ventricular arrhythmias are missing or rare. At present, antiarrhythmic properties and clinical benefit of magnesium application has only been established in patients with torsade de pointes and digitalis-induced ventricular tachyarrhythmias. In perioperative patients at risk for ventricular tachyarrhythmias and in patients suffering from manifest heart failure, data may also indicate some antiarrhythmic properties of magnesium, however, in this case with a wide consensus that the prevention of magnesium deficit is more effective and preferred in most patients over the therapeutic application of magnesium. Another group of patients who may profit from such a therapeutic approach are patients with frequent ventricular arrhythmias and stable underlying heart disease, in whom a recently published double-blind, randomized study documented an antiarrhythmic effect of a 3 week treatment with potassium and magnesium. For all other types of ventricular tachyarrhythmias, the therapeutic use of magnesium can be considered as not harmful, but also as not proven to be effective.