New therapeutic options in congestive heart failure: Part I

Biochemical markers of myocyte injury in heart failure

This review discusses the role of biochemical markers of myocyte injury in patients with chronic congestive heart failure. Heart specific assays have been developed for the measurement of cardiac troponin T (cTnT), cardiac troponin I (cTnI), heart type fatty acid binding protein (H-FABP), and myosin light chain 1 (MLC-1). Concentrations of these biochemical markers increase in the absence of ischaemic events in the subset of patients with heart failure whose long term outcomes are most adverse. The markers are easy to measure serially and it is therefore easy to follow patients without inter-observer variability. The serial clinical use of these markers, separately or in combination, will sharpen our understanding of the state of heart failure.

Inhibition of tumor necrosis factor receptor-1-mediated pathways has beneficial effects in a murine model of postischemic remodeling

The aim of the present study was to investigate the importance of tumor necrosis factor (TNF)-alpha receptor-1 (TNFR1)-mediated pathways in a murine model of myocardial infarction and remodeling. One hundred and ninety-four wild-type (WT) and TNFR1 gene-deleted (TNFR1KO) mice underwent left coronary artery ligation to induce myocardial infarction. On days 1, 3, 7, and 42, mice underwent transesophageal echocardiography. Hearts were weighed, and the left ventricle (LV) was assayed for matrix metalloproteinase (MMP)-2 and -9 activity and for tissue inhibitor of MMP (TIMP)-1 and -2 expression. Deletion of the TNFR1 gene substantially improved survival because no deaths were observed in TNFR1KO mice versus 56.4% and 18.2% in WT males and females, respectively (P < 0.002). At 42 days, LV remodeling, assessed by LV function (fractional area change of 31.9 +/- 7.9%, 32.2 +/- 7.7%, and 21.6 +/- 7.1% in TNFR1KO males, TNFR1KO females, and WT females, respectively, P < 0.04), and hypertrophy (heart weight-to-body weight ratios of 5.435 +/- 0.986, 5.485 +/- 0.677, and 6.726 +/- 0.704 mg/g, P < 0.04) were ameliorated in TNFR1KO mice. MMP-9 activity was highest at 3 days postinfarction and was highest in WT males (1.9 +/- 0.4 4, 3.6 +/- 0.24, 1.15 +/- 0.28, and 1.3 +/- 1.2 ng/100 microg protein, respectively, in TNFR1KO males, WT males, TNFR1KO females, and WT females, respectively, P < 0.002), whereas at 3 days TIMP-1 mRNA fold upregulation compared with type- and sex-matched controls was lowest in WT males (138.32 +/- 13.05, 46.74 +/- 5.43, 186.09 +/- 28.07, and 101.76 +/- 22.48, respectively, P < 0.002). MMP-2 and TIMP-2 increased similarly in all infarcted groups. These findings suggest that the benefits of TNFR1 ablation might be attributable at least in part to the attenuation of cytokine-mediated imbalances in MMP-TIMP activity.

Cardiopulmonary Exercise Testing and Prognosis in Chronic Heart Failure*

The identification of individuals who are at high risk of chronic heart failure (HF) is a medical art of growing concern. Cardiopulmonary exercise stress testing (CPX) has become an important clinical tool to predict outcome. The value of peak oxygen consumption rests in the fact that it integrates elements of cardiac adaptations, and skeletal muscle, pulmonary, and endothelial dysfunctions more than other traditional prognostic indicators of chronic HF. Recently, exercise-related ventilatory abnormalities have gained attention, stimulating scientific debate and an innovative perspective. This review, through a critical examination of previous experiences, will focus on the prognostic application of CPX, defining a proficient outline of treatment for the individual patient.

Functional effects of enhancing or silencing adenosine A2b receptors in cardiac fibroblasts

Cardiac fibroblasts (CF) express adenosine (ADO) receptors, and pharmacological evidence suggests the possible involvement of the A2 (A2a and A2b) receptor (A2aR and A2bR) subtypes in inhibiting cell functions involved in fibrosis. The main objective of this study was to define the contributions of A2a and/or A2b receptors in modulating ADO-induced decreases in CF functions. For this purpose, CF were either treated pharmacologically or had the A2aR or A2bR levels modified through the use of recombinant adenovirus or siRNA. The assessment of mRNA expression in adult rat CF yielded evidence for A1R, A2bR, A2a), and A3R. Endogenously or exogenously enhanced ADO significantly inhibits CF proliferation, collagen, and protein synthesis. A2R and A2aR agonists, although capable of inhibiting CF protein and collagen synthesis, were unable to define the contributions derived from A2aR or A2bR. Overexpression of A2bR in CF yielded significant decreases in basal levels of collagen and protein synthesis and correlated with increases in cAMP levels. However, at higher doses of ADO receptor agonists, significant increases in protein and collagen synthesis were observed. CF with underexpression of A2bR yielded increases in protein and collagen synthesis. In contrast, A2aR underexpression did not modify ADO-induced decreases in CF protein or collagen synthesis. In conclusion, results derived from the molecular manipulation of receptor levels indicate that A2bR are critically involved in ADO-mediated inhibition of CF functions.

Gene and cell-based therapies for heart disease

Heart disease remains the prevalent cause of premature death and accounts for a significant proportion of all hospital admissions. Recent developments in understanding the molecular mechanisms of myocardial disease have led to the identification of new therapeutic targets, and the availability of vectors with enhanced myocardial tropism offers the opportunity for the design of gene therapies for both protection and rescue of the myocardium. Genetic therapies have been devised to treat complex diseases such as myocardial ischemia, heart failure, and inherited myopathies in various animal models. Some of these experimental therapies have made a successful transition to clinical trial and are being considered for use in human patients. The recent isolation of endothelial and cardiomyocyte precursor cells from adult bone marrow may permit the design of strategies for repair of the damaged heart. Cell-based therapies may have potential application in neovascularization and regeneration of ischemic and infarcted myocardium, in blood vessel reconstruction, and in bioengineering of artificial organs and prostheses. We expect that advances in the field will lead to the development of safer and more efficient vectors. The advent of genomic screening technology should allow the identification of novel therapeutic targets and facilitate the detection of disease-causing polymorphisms that may lead to the design of individualized gene and cell-based therapies.

A phase II, double-blind, randomized, placebo-controlled, dose comparative study of the efficacy, tolerability, and safety of MCC-135 in subjects with chronic heart failure, NYHA class II/III (MCC-135-GO1 study): rationale and design

BACKGROUND

Chronic heart failure (CHF) can be caused either by a predominant abnormality in systolic function (systolic heart failure) or a predominant abnormality in diastolic function (diastolic heart failure). Randomized clinical trials have identified a number of pharmaceutical agents that can reduce morbidity and mortality in patients with systolic heart failure. Despite significant therapeutic advances, systolic heart failure continues to result in high rates of morbidity and mortality. In contrast to systolic heart failure, no randomized clinical trials have been performed in patients with diastolic heart failure. Common to the mechanisms causing both systolic and diastolic heart failure are abnormalities in calcium homeostasis. Mitsubishi Pharma Corporation has developed a compound (MCC-135, INN; caldaret) whose mechanism of action is proposed to be modulation of calcium homeostasis at the sarcoplasmic reticulum and cellular membrane. The purpose of this study was to test the safety, tolerability, and efficacy of MCC-135 in patients with mild to moderate heart failure.

METHODS

This was a phase II, multicenter, randomized, double-blind study of parallel group design comparing 3 oral dose regimens of MCC-135 (5 mg, 25 mg, 50 mg, twice daily) with a placebo control. The treatment period was 24 weeks. A total of 511 patients were recruited from 69 centers in the United States and Europe. One hundred and twenty-five patients were recruited in each of the 4 treatment groups. Patients in each treatment group were divided into 2 cohorts: those with an ejection fraction < or = 40%, and those with an ejection fraction >40% as determined by core laboratory analysis of echocardiographic studies.

CONCLUSION

Patient recruitment was completed in September 2002. Patient follow-up was completed by February 2003; the results will be available for release in 2004.

Diastolic heart failure--abnormalities in active relaxation and passive stiffness of the left ventricle

BACKGROUND

Patients with signs and symptoms of heart failure and a normal left ventricular ejection fraction are said to have diastolic heart failure. It has traditionally been thought that the pathophysiological cause of heart failure in these patients is an abnormality in the diastolic properties of the left ventricle; however, this hypothesis remains largely unproven.

METHODS

We prospectively identified 47 patients who met the diagnostic criteria for definite diastolic heart failure; all the patients had signs and symptoms of heart failure, a normal ejection fraction, and an increased left ventricular end-diastolic pressure. Ten patients who had no evidence of cardiovascular disease served as controls. Left ventricular diastolic function was assessed by means of cardiac catheterization and echocardiography.

RESULTS

The patients with diastolic heart failure had abnormal left ventricular relaxation and increased left ventricular chamber stiffness. The mean (+/-SD) time constant for the isovolumic-pressure decline (tau) was longer in the group with diastolic heart failure than in the control group (59+/-14 msec vs. 35+/-10 msec, P=0.01). The diastolic pressure-volume relation was shifted up and to the left in the patients with diastolic heart failure as compared with the controls. The corrected left ventricular passive-stiffness constant was significantly higher in the group with diastolic heart failure than in the control group (0.03+/-0.01 vs. 0.01+/-0.01, P<0.001).

CONCLUSIONS

Patients with heart failure and a normal ejection fraction have significant abnormalities in active relaxation and passive stiffness. In these patients, the pathophysiological cause of elevated diastolic pressures and heart failure is abnormal diastolic function.

Is heart failure different on the two continents (North America and Europe)?

Heart failure is increasing in both North America and Europe. Although many similarities in the disease are apparent between the two continents, differences do exist. Heart failure with preserved systolic function appears to be increasingly important on both continents, and is associated more frequently with hypertension, aging, and female sex. Treatment guidelines from the two continents show more similarities than differences, though different treatment patterns emerge. Because more patients with heart failure will be older in the future, clinical trials that include greater numbers of these patients are needed to demonstrate that therapies are as effective and safe in this population.

Management of heart failure: crossing boundary over to the surgical country

Pharmacologic therapy of heart failure appears to have reached its zenith. Few new agents are likely to replace conventional therapy. It is time for a paradigm shift in heart failure management. Aggressive surgical strategies to remodel the failing ventricle will shape heart failure therapy in the decade ahead. The articles that follow will describe in detail the advances that have been made in "crossing the boundary" to surgical treatment of advanced heart failure.

Why do patients with ischemic cardiomyopathy and a substantial amount of viable myocardium not always recover in function after revascularization?

OBJECTIVE

In patients with ischemic cardiomyopathy and a substantial amount of dysfunctional but viable myocardium, myocardial revascularization may improve left ventricular ejection fraction. The aim of this study was to evaluate why not all patients with a substantial amount of viable tissue recover in function after revascularization.

METHODS

A total of 118 consecutive patients with a depressed left ventricular ejection fraction (on average 29% +/- 6%) due to chronic coronary artery disease underwent myocardial revascularization. Before revascularization all patients underwent dobutamine stress echocardiography to assess regional dysfunction, left ventricular volumes, and myocardial viability as well as radionuclide ventriculography to determine the left ventricular ejection fraction. Next, 3 to 6 months after revascularization, the left ventricular ejection fraction and regional contractile function were reassessed. Improvement of left ventricular ejection fraction > or = 5% following revascularization was considered clinically significant.

RESULTS

Dobutamine stress echocardiography revealed that 489 (37%) of the 1329 dysfunctional segments were viable. A total of 61 (52%) patients had a substantial amount of viable myocardium (> or = 4 viable segments). In these 61 patients the global function was expected to recover > or = 5% after revascularization. However, left ventricular ejection fraction did not improve in 20 (33%) of 61 patients despite the presence of substantial viability. Clinical characteristics and echocardiographic data were comparable between patients with and without improvement. However, patients without improvement had considerably larger end systolic volumes (153 +/- 41 mL vs 133 +/- 46 mL, P =.007). The likelihood of recovery of global function decreased proportionally with the increase of end systolic volume (P <.001, R = 0.43, n = 61). Receiver operating characteristic curve analysis demonstrated that an end systolic volume > or = 140 mL had the highest sensitivity/specificity to predict the absence of global recovery.

CONCLUSIONS

In patients with ischemic cardiomyopathy not only the amount of dysfunctional but viable myocardium but also the extent of left ventricular remodeling determines the improvement in function following myocardial revascularization. Patients with a high end systolic volume due to left ventricular remodeling have a decreased likelihood of improvement of global function.

The aminotetraline derivative (+/-)-(R,S)-5,6-dihydroxy-2-methylamino-1,2,3,4-tetrahydro-naphthalene hydrochloride (CHF-1024) displays cardioprotection in postischemic ventricular dysfunction of the rat heart

To analyze the protective effects of the aminotetraline derivative (+/-)-(R,S)-5,6-dihydroxy-2-methylamino-1,2,3,4-tetrahydro-naphthalene hydrochloride (CHF-1024), a compound endowed with DA2-dopaminergic/alpha2-adrenergic receptor agonistic activity, in myocardial ischemia/reperfusion damage. A model of isolated and perfused (15 ml/min) electrically driven (300 beats/min) rat heart subjected to global ischemia (1 ml/min for 20 min) and reperfusion (15 ml/min for 30 min) was followed. Cardiac mechanics changes were evaluated together with biochemical markers of cardiac ischemia in perfusate and tissue tumor necrosis factor-alpha (TNF-alpha). CHF-1024, perfused through the heart for 15 min before ischemia at different molar concentrations (1-100 nM), significantly improved left ventricle developed pressure during reperfusion, and normalized left ventricular end-diastolic pressure and coronary perfusion pressure. This anti-ischemic effect of CHF-1024 was associated to a decrease in creatine kinase and lactate dehydrogenase, both released during heart reperfusion. These events were concomitant with maintenance of a higher production of 6-keto-prostaglandin F1alpha The ability of CHF-1024 to improve postischemic ventricular dysfunction was correlated with a dose-dependent inhibition of the release of both norepinephrine (NE), from sympathetic nerve endings, and TNF-alpha from cardiac tissue. The effect of CHF-1024 on NE release was almost completely antagonized by specific antagonists of presynaptic inhibitory receptors domperidone and rauwolscine. The finding that this new aminotetraline derivative possesses anti-ischemic properties and limits NE release from cardiac nerve endings may bear some therapeutic potential in cardiovascular diseases.

Novel Pharmacologic Therapy of Heart Failure

The prevalence of congestive heart failure is progressively increasing and despite recent advances in therapeutics, there is a continuing need for novel effective therapies. New, investigational treatment strategies include inotropic drugs, neurohormonal antagonists, anticytokine and anti-inflammatory strategies, hormonal therapies, and nutritional supplements. Current positive inotropes (eg, dobutamine and phosphodiesterase inhibitors) provide symptomatic relief, but newer agents may have a better adverse effect profile. Angiotensin-converting enzyme (ACE) inhibitors should remain first-line treatment with angiotensin receptor blockers used in ACE inhibitor-intolerant patients. Many new neurohormonal antagonists have recently been investigated and eplerenone has demonstrated clinical benefit. New hormonal, anticytokine, and anti-inflammatory therapies have shown benefit in small trials, but results in larger trials have been disappointing. Other approaches are currently being tested in large trials that will clarify their role. Nutritional supplements need to be tested in a large prospective trial before they can be recommended.

A novel D2-dopaminergic and alpha2-adrenoceptor receptor agonist induces substantial and prolonged IOP decrease in normotensive rabbits

The effects of a novel and selective D2-dopaminergic/alpha2-adrenoceptor agonist, CHF1035, and its metabolite CHF1024 on intraocular pressure (IOP) were determined in rabbits. Because CHF1035 is a mixture of two enantiomers, CHF1800 (+) and CHF1810 (-), pure enantiomers were also studied to determine possible differences in IOP-decreasing ability depending on the stereochemistry of the molecule. CHF1035, CHF1800 (+), CHF1810 (-), CHF1024, brimonidine and 0.9% NaCl were administered topically to rabbits and IOP was then measured at fixed time intervals. The dose-response profile (0.01-1.0% w/v) was determined for CHF1035. CHF1035 and its metabolite CHF1024 significantly lowered IOP in the treated eyes. CHF1035 showed a maximum IOP decrease (7.6 +/- 1.5 mmHg) 5 h post-dosing, whereas the metabolite CHF1024 showed a maximum decrease in IOP (7.0 +/- 0.8 mmHg) 3 h post-dosing. The maximum IOP decrease produced by CHF1035 in the treated eye was comparable with that produced by brimonidine (7.8 +/- 0.9 mmHg), but CHF1035 had a significantly longer duration of action. Unlike brimonidine, CHF1035 and CHF1024 did not decrease IOP in the untreated eye. CHF1810 (-) lowered the IOP more than CHF1800 (+). No irritation, evaluated as eyelid closure, was observed after topical administration of any of the compounds. Only in the case of CHF1035 1% solution, two rabbits out of six closed the eye for 30-45 s. In conclusion, CHF1035 and its metabolite CHF1024 significantly decreased the IOP in rabbits, and are potential novel IOP lowering agents. Especially, CHF1035 produced a substantial decrease in IOP for a prolonged period of time, and thus may prove useful in glaucoma therapy.

Plasminogen activator inhibitor-1 in patients with Kawasaki disease: diagnostic value for the prediction of coronary artery lesion and implication for a new mode of therapy

Kawasaki disease (KD) in children takes the form of acute systemic vasculitis, which causes coronary artery dilation and aneurysm formation in 10% to 15% of the patients. We have recently shown that matrix metalloproteinases (MMPs) are intimately involved in coronary arterial wall destruction and the resultant formation of coronary artery lesions (CALs) in this disease. Plasminogen activators (PAs) are known to be a major pathway of MMP activation, and this suggests that their inhibitor, plasminogen activator inhibitor-1 (PAI-1), also plays important roles in the development of CALs in KD. The present study was conducted to test the hypothesis that circulating levels of PAI-I are related to CAL formation in KD. Plasma levels of PAI-1 were measured by enzyme-linked immunoassay in 37 KD patients without CALs (group 1) and 7 KD patients with CALs (group 2). Blood samples were obtained before and after i.v. gammaglobulin therapy (IVGG), and in the convalescent stage. Levels of PAI-1 were significantly higher in KD patients before IVGG than in 18 age-matched healthy control subjects (p < 0.01). More importantly, both pre-IVGG and post-IVGG levels of PAI-1 were significantly higher in group 2 than in group 1 (p < 0.01). Furthermore, PAI-1 levels of 9 patients from group 1 who showed pre-IVGG PAI-1 levels higher than the minimum PAI-1 level in group 2 significantly decreased after IVGG, whereas PAI-1 levels of group 2 patients remained persistently elevated, further suggesting a close association between PAI-1 and CAL development in KD. Thus, PAI-1 may be useful as a predictive marker for CAL development in KD. Studies of the effects of PA inhibition on coronary outcome may provide evidence that PA is a viable therapeutic target for the prevention of KD-related CALs.

Prevention and management of chronic heart failure with electrical therapy

Sudden cardiac death is responsible for >40% of patients with heart failure losing their lives. Thus, the prevention of life-threatening cardiac arrhythmias is a major goal in the management of heart failure. In several randomized clinical trials, electrical therapy with the implantable cardioverter defibrillator (ICD) has proved superior to medical antiarrhythmic therapy in both the secondary and primary prevention of sudden cardiac death in patients with reduced left ventricular function. In addition to the severity of left ventricular dysfunction, the etiology of the cardiomyopathy appears to be a determinant in the benefit derived from this form of electrical therapy. Whereas patients with ischemic cardiomyopathy clearly show improved survival with ICD therapy, outcome data in patients with nonischemic cardiomyopathy are less convincing. The major challenge lies in the risk stratification of patients with heart failure for arrhythmic death. Catheter ablation is another form of electrical therapy that can help in the treatment of patients with heart failure. In patients with a tachycardia-mediated cardiomyopathy because of drug-refractory atrial fibrillation with rapid ventricular response, catheter ablation of the atrioventricular node and pacemaker implantation can effectively restore a physiologic heart rate, often with dramatic regression of left ventricular dysfunction. In patients with frequent ICD therapies because of frequent recurrences of ventricular tachyarrhythmias, catheter ablation of ventricular tachycardia can be an effective adjunctive therapy. New catheter ablation techniques and new atrial pacing algorithms can also significantly reduce the atrial fibrillation burden in patients with heart failure who are particularly susceptible to decompensation because of atrial fibrillation. Pacing for hemodynamic benefit in heart failure has evolved from dual-chamber pacing modes with optimized atrioventricular delay to biventricular pacing resulting in cardiac resynchronization. This new treatment modality for advanced heart failure has been shown to result in significant symptomatic and hemodynamic improvement.

Surgical methods to reverse left ventricular remodeling in congestive heart failure

In this review article, we describe the most common surgical procedures currently used to reverse or arrest remodeling of the left ventricle in patients with congestive heart failure (CHF). The selection of the appropriate operation in a patient is a complex decision-making process, rigorously based on pathophysiologic considerations. In this population, all factors affecting the surgical risk should be carefully evaluated preoperatively, and surgery should be recommended when definite benefits in survival and quality of life can be reasonably predicted. Quite often, patients with CHF require a combination of different procedures to address all the pathophysiologic components determining the clinical picture. In particular, in this review we describe the surgical restoration of the left ventricle, the isolated coronary artery bypass graft procedure, the correction of mitral regurgitation, diastolic support (from dynamic cardiomyoplasty to passive containment), and mechanical assist devices. Moreover, in the future, the role of surgery in the treatment of CHF will be strongly modified by the advent of gene therapy, cell therapy, and engineered artificial myocardial tissue.

Left ventricular assist devices: an alternative to medical therapy for end-stage heart failure

Although aggressive medical therapy and ultimately cardiac transplantation have long been the therapeutic mainstays for patients with end-stage heart failure, the left ventricular assist device (LVAD), which was originally used clinically as a bridge to transplantation, may also be used as destination therapy. LVAD therapy for selected patients has been shown in the REMATCH trial to be superior to medical therapy in ameliorating symptoms and improving outcome in patients with terminal heart failure. LVAD therapy has also proved useful in improving native heart function by neuroendocrine modulation and reverse remodeling. Furthermore, current evidence suggests that when LVAD therapy is utilized to improve ventricular function, it may be further enhanced when combined with aggressive medical therapy.

Emerging therapeutic targets in chronic heart failure: part I

Chronic heart failure (CHF) is a life threatening disease with an enormous medical requirement. Approximately 15 million people worldwide suffer from CHF. The prevalence will inevitably increase due to the ageing population. Nevertheless, current treatment options based on angiotensin-converting enzyme inhibitors and beta-adrenergic receptor antagonists merely slow progression of the disease. Novel treatment concepts based on new therapeutic targets must have the capability to reverse the severity of this disease. This review, focusing on the emerging targets in the most promising therapeutic areas for the treatment of CHF, will be divided into two parts. In Part I, disease concepts such as altered calcium handling and ion channel activity, pathophysiological hypertrophy and inefficient cardiac metabolism are discussed. Validation status and potential therapeutic value for new targets in each research field is given by summarising the results of in vitro and in vivo studies.

Renin-angiotensin system inhibition: how much is too much of a good thing?

Inhibitors of the renin-angiotensin system (RAS) are valuable therapeutic agents for a wide range of clinical conditions. Increasingly, consideration is being given to the combination of angiotensin-converting enzyme (ACE) inhibitors and angiotensin-II receptor (AR) antagonists to obtain more complete inhibition of the RAS than can be achieved by either agent alone. Beta-blockers also inhibit the RAS by inhibiting renin secretion. Whereas the combination of an ACE inhibitor and AR antagonist represents dual RAS inhibition, the combination of both of these agents with beta-blocker therapy represents triple RAS inhibition. Animal studies indicate that complete blockade of the RAS produces adverse effects. Moreover, post-hoc analysis of the recent Valsartan Heart Failure Trial study suggests that the combination of ACE inhibitor and AR antagonist therapies may have an adverse effect in heart failure when combined with beta-blocker therapy. There is therefore a need for caution in the combination of ACE inhibition and AR antagonism, particularly in patients receiving beta-blockers, until the impact of this strategy is evaluated.

Pacemakers, recent directions and developments

PURPOSE OF REVIEW

Pacemaker and implantable cardiovertor defibrillator utilization is evolving rapidly. Expanding indications are reviewed.

RECENT FINDINGS

Current pacemakers are smaller, more dependable, longer lasting and have rate-adaptive features. Implantable cardiovertor defibrillators use transvenous leads and have advanced pacing abilities. Primary pacing indications remain sinus node dysfunction or atrioventricular conduction abnormalities. Dual-chamber pacemakers compared with single chamber ventricular pacemakers, have small quality of life advantages and result in less atrial fibrillation, but decrease stroke rates and mortality. In congestive heart failure patients with delayed ventricular conduction, cardiac resynchronization therapy (atrially timed biventricular pre-excitation) improves physiological parameters, performance indices and quality of life. Atrial arrhythmias may be prevented or treated with appropriate pacing strategies. Pacing-related improvements for symptomatic neurally mediated syncope and symptomatic hypertrophic obstructive cardiomyopathy have been demonstrated. For patients with coronary artery disease and low ejection fractions, implantable cardiovertor defibrillators are well established in the secondary prevention of sudden death, and may be helpful for primary prevention if there are inducible ventricular arrhythmias. Combining cardiac resynchronization and implantable cardiovertor defibrillators in similar patients is under investigation. The role of atrial defibrillators is being defined. Electromagnetic interference remains possible with these devices, particularly in electromagnetically hostile environments.

SUMMARY

More pacemakers and implantable cardiovertor defibrillators will be encountered. Despite increasing sophistication, most often only basic anti-bradycardia modes are essential in the perioperative setting. Understanding the indications for implantation will help the anesthesiologist better support the physiological needs of the patient. Existing perioperative pacemaker-related guidelines for the anesthesiologist still apply.

New therapeutics that antagonize endothelin: promises and frustrations

The discovery of endothelin--a highly potent endogenous vasoconstrictor - in 1988 has led to considerable efforts to develop antagonists of endothelin receptors that could have therapeutic potential in disorders including hypertension, heart failure and renal diseases. However, in general, the results of trials in humans have not mirrored the highly promising effects in animal disease models. Here, we discuss preclinical and clinical results with endothelin antagonists, and consider possible approaches to fully realizing the potential of endothelin antagonism.