Comparison of permanent left ventricular and biventricular pacing in patients with heart failure and chronic atrial fibrillation: prospective haemodynamic study

OBJECTIVE

To compare clinical and haemodynamic variables between left ventricular and biventricular pacing in patients with severe heart failure; and to analyse haemodynamic changes during daily life and maximum exercise during chronic left ventricular and biventricular pacing.

DESIGN

Prospective single blinded randomised study with crossover.

SETTING

University hospital (tertiary referral centre).

PATIENTS AND METHODS

13 patients (mean (SD) age, 62 (6) years) with chronic atrial fibrillation, severe heart failure (mean ejection fraction 24 (8)%), and QRS prolongation of > or = 140 ms had His bundle ablation and installation of a pacemaker providing left ventricular and biventricular pacing. The pacemaker was equipped with a peak endocardial acceleration (PEA) sensor. The PEA pattern was used as a haemodynamic marker during exercise as it is highly correlated with left ventricular dP/dt. After a baseline period of right ventricular pacing, all patients had two months of left ventricular pacing and two months of biventricular pacing in random order. At the end of each phase, an echocardiogram, a haemodynamic analysis at rest and on exercise during a six minute walk test, and a cardiopulmonary exercise test were performed.

RESULTS

PEA values were higher with left ventricular pacing (0.58 (0.38) m/s) and biventricular pacing (0.62 (0.24) m/s) than at baseline (0.49 (0.18) m/s) (p < 0.05). The six minute walk test showed similar performance in both pacing modes, but patients had more symptoms with left ventricular pacing at the end of the test (p = 0.035). On cardiopulmonary exercise testing, there was a greater increase in mean percentage variation of PEA with biventricular pacing than with left ventricular pacing (125 (18)% v 97 (36)%, respectively; p = 0.048) and better performance figures (92 (34) W v 77 (23) W; p = 0.03).

CONCLUSIONS

During symptom limited and daily life exercise tests, chronic biventricular pacing provides better haemodynamic performance than left ventricular pacing. In heart failure patients with wide QRS complexes, the interventricular dyssynchronisation induced by left ventricular pacing may impair myocardial function during exercise.

Left ventricular assist device as bridge to transplantation in patients with end-stage heart failure: Eight-year experience with the implantable HeartMate LVAS

OBJECTIVE

To evaluate the use of left ventricular assist devices (LVAD) as bridge to heart transplantation (HTx) in patients with end-stage heart failure.

METHOD

Between March 1993 and December 2001, 38 patients with refractory end-stage heart failure underwent HeartMate LVAD (Thoratec, Pleasanton Calif.) implantation.

RESULTS

A total of 33 of the 38 patients (87%) survived the implantation and perioperative period. There were five perioperative deaths (13%), two due to right ventricular failure, two as a result of bleeding and one probably due to septic shock at the time of LVAD implantation. Three patients (9%) died late in the postoperative period due to septic shock, mechanical failure of the device and a cerebral embolus resulting from LVAD endocarditis, initiated by an acute cholecystitis. Twelve patients (32%) had one or more infectious episodes during long-term assist, of which one patient died. Four patients are still on the device, waiting for a heart transplantation. Twenty-six patients (76%) underwent HTx after 206±129 days of support.

CONCLUSION

These results show the efficacy of LVAD support as a bridge to heart transplantation in patients with end-stage heart failure. Major long-term complications are infections and mechanical failure of the device.

Reduced coronary vasodilator responses to amlodipine in pacing-induced heart failure in conscious dogs: role of nitric oxide

1. This study examined whether NO is involved in the in-vivo coronary vasodilator effects of amlodipine (a calcium channel blocker) and whether heart failure (HF) alters the coronary responses to amlodipine. 2. Nine conscious dogs were chronically instrumented to measure circumflex coronary blood flow (CBF) and coronary diameter (CD). Drugs were administered directly into the circumflex artery through an indwelling catheter to avoid systemic changes. HF was induced by right ventricular pacing (240 b.p.m., 3 weeks). 3. Compared with control (C), in HF, coronary responses to acetylcholine (1 - 10 ng kg(-1)) were reduced while responses to nitroglycerin (0.1 - 0.5 microg kg(-1)) were unchanged. In C, amlodipine (30 - 150 microg kg(-1)), increased dose-dependently CBF and CD. After LNA (a NO synthase inhibitor, 2 mg kg(-1)), amlodipine produced less increases in CBF and CD (+121+/-26 ml min(-1) and +76+/-35 microm versus +196+/-40 ml min(-1) and +153+/-39 microm respectively for 150 microg kg(-1) amlodipine alone, both P<0.05). In HF, the coronary responses to amlodipine were reduced (150 microg kg(-1) of amlodipine increased CBF and CD +121+/-23 ml min(-1) and +77+/-21 microm respectively, both P<0.05). After LNA, the CBF responses to amlodipine tended to be reduced (+94+/-19 ml min(-1) at 150 microg kg(-1)) but CD responses were significantly reduced (+41+/-16 microm, P<0.05). The supplementation with L-arginine did not enhance the coronary responses to amlodipine. 4. These results indicate that, in conscious dogs, NO participates in the coronary responses to amlodipine and in HF, the coronary responses to amlodipine are reduced, which is related to a reduced NO production.

Novel use of a short-acting intravenous beta blocker in combination with inotropic therapy as a bridge to chronic oral beta blockade in patients with advanced heart failure

The role for beta blockers in advanced heart failure (New York Heart Association class IV) remains undefined because of concerns about tolerability and uncertainty about efficacy. We report the use of a short-acting intravenous beta blocker in combination with inotropic therapy as a means to bridge five patients with advanced heart failure to chronic oral beta blockade; two of these patients had been chronically managed with intravenous inotrope. At 4 months' follow-up, all patients remained on beta-blocker therapy and none was hospitalized for heart failure or had received intravenous diuretics. Given the early separation of survival curves in the randomized clinical trials of beta blockers in heart failure, it is possible that these patients will accrue a survival benefit. We conclude that some patients with advanced heart failure can be offered oral beta-blocker therapy by bridging with a combination of intravenous inotrope and short-acting intravenous beta blocker.

Effect of multisite pacing on ventricular coordination

OBJECTIVE

To determine the effect of multisite pacing on left ventricular function.

DESIGN

Prospective observational study.

PATIENTS

18 patients with heart failure with a dilated poorly functioning left ventricle (LV) and left bundle branch block.

INTERVENTIONS

Pacing for 5 minutes in random order at the right ventricle (RV) apex, RV outflow tract, mid posterolateral LV, RV apex and LV simultaneously, and RV outflow tract and LV simultaneously. The best achieved measurements with RV, LV, and biventricular pacing were compared.

MAIN OUTCOME MEASURES

LV dimension, filling characteristics, and long axis indices were measured on echocardiography simultaneously with LV pressure. Cycle efficiency (%)--that is, the ratio of the area of the acquired pressure dimension loop to that of the ideal loop for that segment--quantified coordination.

RESULTS

The pacing site that gave the best achieved cycle efficiency differed between patients (biventricular in five, LV in two, RV in seven, and no site in four). In patients with baseline incoordination (cycle efficiency < or = 72%, n = 12) cycle efficiency improved significantly with RV pacing (cycle efficiency 76%, p = 0.01) but not with LV (65%) or biventricular (67%) pacing. LV based pacing induced premature short axis contraction in a subset of patients (n = 4), which was associated with a prolonged time from the Q wave on the ECG to the onset of inward movement of the long axis (from apex to mitral ring): biventricular 145 ms, LV 105 ms, RV 85 ms (biventricular v RV, p < 0.05). Excluding patients with baseline incoordination in whom premature activation occurred, pacing at all sites led to a similar increase in cycle efficiency (RV 78%, LV 72%, biventricular 73%).

CONCLUSIONS

Ventricular coordination can be improved with pacing in patients with baseline incoordination. Short and long axis fibres may be asynchronised in a subset of patients with LV or biventricular pacing, which may worsen coordination. The clinical significance of these findings remains to be defined.

Increased pericardial fluid concentrations of the mature form of adrenomedullin in patients with cardiac remodelling

BACKGROUND

There is evidence that adrenomedullin has autocrine or paracrine activities that oppose cardiac remodelling. However, it remains unclear whether it exerts those local functions in heart failure patients.

OBJECTIVE

To investigate the relation between plasma and pericardial fluid concentrations of adrenomedullin and left ventricular haemodynamic variables.

DESIGN

Samples of plasma and pericardial fluid were obtained from 50 patients undergoing cardiac surgery. They were classified into two groups: group N (n = 27) with a left ventricular end diastolic volume index (LVEDVI) < or = 90 ml/m(2); and group R (n = 23) with LVEDVI > 90 ml/m(2). Plasma and pericardial fluid concentrations of total adrenomedullin (tAM) and mature adrenomedullin (mAM) were measured and related to the preoperative haemodynamic variables.

RESULTS

Pericardial fluid concentrations of mAM were much higher than the plasma concentration in both group N and group R (mean (SEM), 10.6 (1.7) v 3.3 (0.2) fmol/ml, p = 0.0001; and 21.2 (2.8) v 3.9 (0.3) fmol/ml, p < 0.0001, respectively). The ratio mAM/tAM in pericardial fluid was significantly higher than in plasma (0.56 (0.02) v 0.28 (0.02), p < 0.0001). Pericardial fluid concentrations of mAM, but not plasma concentrations, were significantly correlated with LVEDVI, left ventricular end systolic volume index, left ventricular ejection fraction, and left ventricular mass index (r = 0.60, 0.63, -0.54, and 0.47, respectively).

CONCLUSIONS

Raised pericardial fluid concentrations of mAM may reflect the actions of adrenomedullin as a local mediator against cardiac remodelling in patients with left ventricular dysfunction.

Targeting phospholamban by gene transfer in human heart failure

BACKGROUND

Myocardial cells from failing human hearts are characterized by abnormal calcium handling, a negative force-frequency relationship, and decreased sarcoplasmic reticulum Ca2+ ATPase (SERCA2a) activity. In this study, we tested whether contractile function can be improved by decreasing the inhibitory effects of phospholamban on SERCA2a with adenoviral gene transfer of antisense phospholamban (asPL).

METHODS AND RESULTS

Myocardial cells isolated from 9 patients with end-stage heart failure and 18 donor nonfailing hearts were infected with adenoviruses encoding for either the antisense of phospholamban (Ad.asPL), the SERCA2a gene (Ad.SERCA2a), or the reporter genes beta-galactosidase and green fluorescent protein (Ad.betagal-GFP). Adenoviral gene transfer with Ad.asPL decreased phospholamban expression over 48 hours, increasing the velocity of both contraction and relaxation. Compared with cardiomyocytes infected with Ad.asPL (n=13), human myocytes infected with Ad.betagal-GFP (n=8) had enhanced contraction velocity (20.3 +/- 3.9% versus 8.7 +/- 2.6% shortening/second; P<0.01) and relaxation velocity (26.0 +/- 6.2% versus 8.6 +/- 4.3% shortening/second; P<0.01). The improvement in contraction and relaxation velocities was comparable to cardiomyocytes infected with Ad.SERCA2a. Failing human cardiomyocytes had decreased contraction and Ca2+ release with increasing frequency (0.1 to 2 Hz). Phospholamban ablation restored the frequency response in the failing cardiomyocytes to normal; increasing frequency resulted in enhanced sarcoplasmic reticulum Ca2+ release and contraction.

CONCLUSION

These results show that gene transfer of asPL can improve the contractile function in failing human myocardium. Targeting phospholamban may provide therapeutic benefits in human heart failure.

Evidence for a role of mast cells in the evolution to congestive heart failure

Mast cells are believed to be involved in the pathophysiology of heart failure, but their precise role in the process is unknown. This study examined the role of mast cells in the progression of heart failure, using mast cell-deficient (WBB6F1-W/W(v)) mice and their congenic controls (wild-type [WT] mice). Systolic pressure overload was produced by banding of the abdominal aorta, and cardiac function was monitored over 15 wk. At 4 wk after aortic constriction, cardiac hypertrophy with preserved left ventricular performance (compensated hypertrophy) was observed in both W/W(v) and WT mice. Thereafter, left ventricular performance gradually decreased in WT mice, and pulmonary congestion became apparent at 15 wk (decompensated hypertrophy). In contrast, decompensation of cardiac function did not occur in W/W(v) mice; left ventricular performance was preserved throughout, and pulmonary congestion was not observed. Perivascular fibrosis and upregulation of mast cell chymase were all less apparent in W/W(v) mice. Treatment with tranilast, a mast cell-stabilizing agent, also prevented the evolution from compensated hypertrophy to heart failure. These observations suggest that mast cells play a critical role in the progression of heart failure. Stabilization of mast cells may represent a new approach in the management of heart failure.

Effects of cardioselective KATP channel antagonism on basal, stimulated, and ischaemic myocardial function in in vivo failing canine heart

Inhibition of cardiomyocyte-specific ATP-sensitive potassium (K(ATP)) channels prolongs the action potential during intense ischaemia with attendant antiarrhythmic effects. However, this is accompanied by contractile depression in some models. These changes may be particularly troublesome in dilated cardiomyopathic hearts that display basal systolic dysfunction, limited energy reserve, and prolonged repolarization favouring arrhythmia. Mechanical effects of selective myocyte K(ATP) channel blockade on basal, beta-adrenergic stimulated, and ischemic responses were therefore tested in dogs with cardiac failure induced by tachypacing. Cardiovascular function was assessed by pressure - dimension relationships in 10 conscious, chronically instrumented dogs (sonomicrometry/micromanometry), with or without cardiac failure. Cardiomyocyte K(ATP) channels were inhibited by HMR 1098, and data obtained under basal conditions, during epinephrine infusion to raise metabolic demand, during regional ischaemia, and with combined ischaemia+epinephrine. HMR 1098 had no effect on baseline cardiac function nor did it induce arrhythmia in normal or failing hearts. Epinephrine raised cardiac work 65% and oxygen consumption 55%, yet HMR 1098 had no functional effect in either heart condition. Regional ischaemia with or without epinephrine co-stimulation depressed regional and global function, yet both were also unaffected by HMR 1098. There was minimal arrhythmia without HMR 1098, and drug infusion did not alter this. Thus, myocyte-K(ATP) channels play a negligible role modulating intact in vivo cardiac contraction or arrhythmia in normal and failing heart with and without increased metabolic demand and/or regional ischaemia. This supports the feasibility of administering such agents to depressed hearts, despite underlying contractile and electrophysiologic abnormalities.

Tumour necrosis factor alpha gene polymorphism: a predisposing factor to non-ischaemic myocardial dysfunction?

BACKGROUND

Tumour necrosis factor alpha (TNF alpha) is implicated in the pathophysiology of heart failure. Plasma TNF alpha is raised in patients with myocardial dysfunction in proportion to the symptoms.

OBJECTIVE

To determine whether this genetic variant is over represented in heart transplant recipients.

PATIENTS

175 heart transplant recipients and a control group of 212 healthy volunteers were studied. The reason for transplantation was severe symptomatic myocardial dysfunction in all cases.

METHODS

The TNF alpha genotype was determined by polymerase chain reaction and gel electrophoresis. The populations were compared for their fit to Hardy-Weinberg equilibrium by calculating the expected frequencies of each genotype and comparing them to the observed values. A chi(2) test was used to determine the significance of the difference between the observed and expected values.

RESULTS

No differences were found in the frequency of the TNF2 allele between all heart transplant recipients taken together (54/175, 31%) and healthy volunteers (58/212, 27%). A higher proportion of TNF2 allele carriers was present in cardiac recipients with a pretransplant diagnosis of viral mediated or idiopathic heart failure than in those with ischaemic myocardial dysfunction (26/69 (37.7%) v 28/106 (26.4%), p = 0.03). PATIENTS with a non-ischaemic aetiology had a higher prevalence of TNF2 than healthy volunteers (26/69 (37.7%) v 58/212 (27%), p = 0.05).

CONCLUSIONS

The TNF2 allele is overrepresented in patients with end stage non-ischaemic myocardial dysfunction. This may represent a genetic predisposition in a small subset of patients who could respond favourably to anti-TNF alpha treatment.

Left ventricular long axis function in diastolic heart failure is reduced in both diastole and systole: time for a redefinition?

OBJECTIVE

To test the hypothesis that, when measured in the long axis, left ventricular systolic function is abnormal in patients with diastolic heart failure.

DESIGN

A case-control study.

SETTING

University teaching hospital (tertiary referral centre).

PATIENTS

68 patients with heart failure, 29 with a left ventricular ejection fraction (LVEF) of > 0.45 and diastolic dysfunction (diastolic heart failure), 39 with an LVEF of </= 0.45 (systolic heart failure), and 105 normal subjects, including 33 age matched controls.

METHODS

LVEF was measured by cross sectional Simpson's method, and mitral annular amplitudes and velocities by M mode and tissue Doppler echocardiography, respectively, along with mitral Doppler inflow velocities. Results were compared between the three groups.

MAIN OUTCOME MEASURES

Peak systolic mitral annular velocity and amplitude between the different groups.

RESULTS

The mitral annular peak mean velocity and amplitude in systole were lower in the patients with diastolic heart failure (mean (SEM), 4.8 (0.2) cm/s) than in the age matched normal controls (6.1 (0.14) cm/s), but higher than those with systolic heart failure (2.8 (0.13) cm/s) (all p < 0.001). Similar changes were seen the mitral annular amplitude during systole. Peak early diastolic velocity and amplitude were also significantly reduced in the group with diastolic heart failure. Left ventricular hypertrophy was evident in over 95% patients in both diastolic and systolic heart failure groups, with a comparable left ventricular mass index.

CONCLUSIONS

In patients with diastolic heart failure and evidence of left ventricular hypertrophy, there is systolic left ventricular impairment as measured by myocardial Doppler imaging of the longitudinal axis. Thus subtle abnormalities of systolic function are present in patients with heart failure and a normal left ventricular ejection fraction, and there appears to be a continuum of systolic function between those with truly normal, mildly impaired (labelled diastolic heart failure), and obviously abnormal left ventricular systolic function. Isolated diastolic dysfunction is uncommon.

[Medical care of patients with heart failure: clinical characteristics, determinants of prognosis and follow-up in primary care]

OBJECTIVE

To assess the process of care and prognosis of patients with heart failure (HF) attended in a tertiary hospital and follow up at the primary care level.

DESIGN

Prospective study of 18 months of follow up.Setting. Tertiary hospital and primary care centers of the reference area. Participants. Patients admitted to a tertiary hospital from the first of july until de 31 of december of 1998.

OUTCOME MEASUREMENTS

Pharmacological data and morbimortality at discharge and at the end of the follow-up, functional capacity of survivors.

RESULTS

265 patients were included, with a mean age of 75 years, 57% were females, 73.8% had HF as first diagnosis, 6.1% had MI, and 20% were attended for other medical reasons. The most frequent cause of HF was HTA. Drugs more prescribed at the discharge and follow up were diuretics and ACE inhibitors. Hospital mortality was 6.4% and mortality at the end of the follow-up was 46% (in 77% of those for cardiac reasons). After being discharged 38.5% of the patients were readmitted to the hospital with the diagnosis of HF, 72% were visited by the family physician, 43% at the outpatient clinic and 33% by the cardiologist; 60% of the patients who survived were in I-II NYHA functional class, 76% walked regularly, and 25% did recreational activities and physical exercise.

CONCLUSIONS

Patients attended at the hospital with HF are an old population, have frequently associated other chronic diseases, and have a very bad prognosis. These patients spend an important amount of health resources. Drug prescription at the follow up is suboptimum. Patients who survived have an acceptable functional capacity.

Cirrhotic cardiomyopathy: a pathophysiological review of circulatory dysfunction in liver disease

The systemic circulation in patients with cirrhosis is hyperdynamic with an increased cardiac output and heart rate and a reduced systemic vascular resistance as the most pronounced alterations. The concomitant cardiac dysfunction has recently been termed "cirrhotic cardiomyopathy", which is an entity different from that seen in alcoholic heart muscle disease. Clinically, these patients present with sodium fluid retention and strain often unmasks the presence of latent heart failure. No specific treatment can yet be recommended but caution should be used with respect to procedures that may stress the heart such as shunt implantation and liver transplantation.

"Diastolic heart failure" or heart failure caused by subtle left ventricular systolic dysfunction?

OBJECTIVES

To determine whether patients with suspected heart failure but preserved systolic function, as determined by conventional echocardiographic measures (often said to have "diastolic heart failure), might have subtle left ventricular systolic dysfunction detectable by a new measure of left ventricular systolic function-left ventricular systolic atrioventricular plane displacement.

DESIGN

Observational study.

SETTING

Direct access echocardiography.

PATIENTS

147 patients with suspected heart failure referred by general practitioners.

MEASUREMENTS

Echocardiographic assessment of conventional measures of left ventricular systolic function (fractional shortening, ejection fraction (by Simpson's biplane method) and "eyeball" assessment) and measurement of left ventricular systolic atrioventricular plane displacement.

RESULTS

Between 21% and 33% of patients with "normal" left ventricular systolic function by conventional methods were found to have abnormal left ventricular systolic atrioventricular plane displacement.

CONCLUSIONS

Approximately one quarter of patients with suspected heart failure but preserved systolic function by conventional methods have abnormal atrioventricular plane displacement. These patients with suspected heart failure but preserved systolic function by conventional echocardiographic measures may have heart failure caused by subtle systolic dysfunction rather than isolated "diastolic heart failure".

Ventricular assist device support for management of sustained ventricular arrhythmias

We describe herein the cases of 2 patients who had ventricular arrhythmias. In one, a short-term biventricular assist device, the ABIOMED BVS 5000, was placed because the patient had sustained ventricular tachycardia and could not be weaned from cardiopulmonary bypass. Excellent hemodynamic support was maintained for several days while the antiarrhythmic therapy was maximized. Sinus rhythm was restored, and the patient was successfully weaned from the ventricular assist device. However, the substrate for the arrhythmia persisted, and a recurrence, 1 week later, resulted in the patient's death. In the 2nd patient, the use of an implantable left ventricular assist device was successful in temporarily alleviating the ventricular tachycardia associated with ischemic cardiomyopathy. However, after 2 days of device assistance, the patient experienced a recurrence of the tachycardia, which degenerated into ventricular fibrillation with a marked deterioration in the patient's hemodynamics. The arrhythmia persisted despite multiple attempts at external cardioversion, and internal cardioversion and placement of an automatic implantable cardioverter-defibrillator were necessary. This treatment, along with repeated boluses of amiodarone, led to successful suppression of the arrhythmias, and the patient eventually underwent transplantation. The mechanical hemodynamic support of the circulation by ventricular assist devices was effective in supporting these 2 patients who had sustained ventricular arrhythmias.

Validation of Heart Failure Events in the Antihypertensive and Lipid Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) Participants Assigned to Doxazosin and Chlorthalidone

BACKGROUND: The Antihypertensive and Lipid Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) is a randomized, double-blind, active-controlled trial designed to compare the rate of coronary heart disease events in high-risk hypertensive participants initially randomized to a diuretic (chlorthalidone) versus each of three alternative antihypertensive drugs: alpha-adrenergic blocker (doxazosin), ACE-inhibitor (lisinopril), and calcium-channel blocker (amlodipine). Combined cardiovascular disease risk was significantly increased in the doxazosin arm compared to the chlorthalidone arm (RR 1.25; 95% CI, 1.17-1.33; P <.001), with a doubling of heart failure (fatal, hospitalized, or non-hospitalized but treated) (RR 2.04; 95% CI, 1.79-2.32; P <.001). Questions about heart failure diagnostic criteria led to steps to validate these events further. METHODS AND RESULTS: Baseline characteristics (age, race, sex, blood pressure) did not differ significantly between treatment groups (P <.05) for participants with heart failure events. Post-event pharmacologic management was similar in both groups and generally conformed to accepted heart failure therapy. Central review of a small sample of cases showed high adherence to ALLHAT heart failure criteria. Of 105 participants with quantitative ejection fraction measurements provided, (67% by echocardiogram, 31% by catheterization), 29/46 (63%) from the chlorthalidone group and 41/59 (70%) from the doxazosin group were at or below 40%. Two-year heart failure case-fatalities (22% and 19% in the doxazosin and chlorthalidone groups, respectively) were as expected and did not differ significantly (RR 0.96; 95% CI, 0.67-1.38; P = 0.83). CONCLUSION: Results of the validation process supported findings of increased heart failure in the ALLHAT doxazosin treatment arm compared to the chlorthalidone treatment arm.

Effect of aspirin on vasodilation to bradykinin and substance P in patients with heart failure treated with ACE inhibitor

AIMS

We wanted to examine some of the mechanisms by which aspirin might be responsible for counteraction of the effects of ACE inhibitors. Aspirin has been reported to counteract the effects of ACE inhibitors in patients with heart failure. Despite this, there is little evidence on what the mediator of such an effect might be, although there is some evidence to implicate bradykinin and, perhaps, substance P.

METHODS

Twelve patients with congestive heart failure treated with an ACE inhibitor were studied on two occasions, after abstaining from aspirin for 14 days, and after 14 days of aspirin 150 mg once daily. Forearm blood flow was measured by venous occlusion plethysmography during intrabrachial infusions of bradykinin and substance P, before and after intrabrachial aspirin.

RESULTS

Bradykinin caused profound vasodilation (peak 390%, 95% confidence intervals (CI) 300, 480%; P < 0.01), substance P slightly less (peak 222%, 95% CI 162, 283%; P < 0.01). Intra-brachial aspirin had no effect on its own. The response to bradykinin was unchanged by intrabrachial aspirin (peak 404%, 95% CI 304, 504%) or oral aspirin (peak 320%, 95% CI 209, 431%; P = 0.2). The response to substance P was unchanged by intrabrachial aspirin (peak 226%, 95% CI 171, 281%) or oral aspirin (peak 220%, 95% CI 142, 297%; P = 0.86).

CONCLUSIONS

Aspirin has no effect on the vasodilator response to bradykinin and substance P in patients with heart failure treated with an ACE inhibitor. Neither bradykinin nor substance P is likely to contribute to the reported interaction between aspirin and ACE inhibitors.

Carvedilol in the failing heart

Patients with chronic heart failure due to left ventricular systolic dysfunction of ischemic or nonischemic etiology have shown improvement in morbidity and mortality with carvedilol therapy. In patients with symptomatic (New York Heart Association class II-IV) heart failure, carvedilol improves left ventricular ejection fraction and clinical status, and slows disease progression, reducing the combined risk of mortality and hospitalization. Despite the overwhelming evidence for their benefit, there continues to be a large treatment gap between those who would derive benefit and those who actually receive the drug. In this article, the pharmacology, clinical trial evidence, and the potential differences between carvedilol and other beta blockers are discussed. Carvedilol provides powerful therapy in the treatment of chronic heart failure caused by a variety of etiologies and in a wide array of clinical settings.