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Query: UMLS:C0018801 (heart failure)
 72,216 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Organic nitrates have frequently been used for the treatment of patients with congestive heart failure (CHF). Nitrate tolerance has been identified as a major limitation of this therapy preventing a continuous effect. In the past several years, an effort has been made to develop strategies to prevent nitrate tolerance. Recent animal experimentation has demonstrated the prevention of nitrate tolerance with a concomitant administration of hydralazine. A later study demonstrated similar results in a patient with chronic CHF. The use of oral hydralazine (75 mg qid) resulted in prevention of early development of nitrate tolerance and attenuation of nitrate mediated hemodynamic effects which occurred within the first several hours after initiation of nitroglycerin therapy in the control group not receiving hydralazine. Recent data obtained in in vitro studies have demonstrated enhancement of vascular superoxide production secondary to exposure to nitrates which may be an important mechanism leading to nitrate tolerance. These same studies demonstrated a strong antioxidant effect of hydralazine reducing superoxide formation and preventing nitrate tolerance. Both animal and human experiments have demonstrated prevention of nitrate tolerance with a concomitant use of hydralazine. In vitro studies suggest that hydralazine, by virtue of its antioxidant effect, prevents the nitrate-mediated formation of vascular superoxide, and thus prevents nitrate tolerance. These data provide an explanation for the benefit demonstrated in the V-HeFT studies with the combination of isosorbide dinitrate and hydralazine in the treatment of patients with chronic CHF, and provide a support for the use of this therapeutic regimen in the treatment of patients with chronic heart failure.
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PMID:Prevention of nitrate tolerance with concomitant administration of hydralazine. 863 19

Nitrates have been widely used for the treatment of patients with chronic congestive heart failure. Although the use of these drugs has not been evaluated by large-scale studies traditionally used for evaluation of new therapy, multiple studies over the years have demonstrated their favorable effects. Organic nitrates have been shown to have a beneficial effect on ischemia, hemodynamic profile, magnitude of mitral regurgitation, endothelial function, and cardiac remodeling. These drugs alone or in combination with hydralazine have improved exercise capacity, maximal oxygen consumption, cardiac function, and survival. The use of nitrates in patients with heart failure has been limited by reduced responsiveness (resistance) and early development of tolerance. Nitrate resistance is due to reduced vascular response and results in the need to use a larger dose of any nitrate preparation when used for the treatment of patients with heart failure compared to patients without heart failure. Recent information suggests that nitrate tolerance is caused by increased levels of superoxide at the vascular wall, which leads to reduced nitric oxide level and to increased sensitivity to vasoconstrictive mechanisms, such as endothelin and angiotensin II. Intermittent dosing of nitrates allowing a 12-hour nitrate-free interval is effective in preventing nitrate tolerance and is, therefore, recommended. Recent information suggests that augmentation of nitrate dose by the use of an escalating dose regimen and a concomitant use of hydralazine can prevent or overcome the effect of nitrate tolerance in patients with heart failure.
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PMID:Nitrates in the treatment of congestive heart failure. 863 26

For nitrates their efficacy in acute and chronic heart failure has to be differentiated. In acute heart failure the hemodynamic and symptomatic improvements after administration of short term nitrate therapy render this form of therapy a standard medication. In contrast, the therapy with nitrates in chronic heart failure has not significantly improved prognosis especially when compared with ACE-inhibitors. On the contrary, nitrates in chronic heart failure tend to increase the sympathetic tone which is negatively correlated to survival. Thus, nitrates are only adjunctive therapy in patients with chronic heart failure.
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PMID:[The role of nitrates in therapy of heart failure]. 876 23

It has been reported that nitroglycerin (GTN) tolerance can be prevented by the concurrent administration of hydralazine. Although the mechanism of this effect remains unknown, it is possible that hydralazine modifies counter-regulatory responses to nitrate administration. To address this question, we examined the impact of hydralazine therapy on the development of tolerance during sustained therapy with GTN. Twenty normal volunteers and 18 patients with chronic heart failure (mean ejection fraction 30 +/- 2%) were treated for 1 week with hydralazine or placebo in a randomized double-blind fashion. Hydralazine therapy (or placebo) was continued, and subjects then received continuous transdermal GTN for 5 to 7 days. On the first and last day of transdermal GTN therapy, standing HR, systolic blood pressure and hematocrit responses were assessed. HR and blood pressure responses to sublingual GTN (0.6 mg) were also evaluated before and during sustained transdermal GTN therapy. Significant loss of the hemodynamic effects of transdermal GTN occurred during sustained therapy in both the normal volunteer and heart failure groups. Hydralazine had no effect on the development of tolerance to the hemodynamic effect of GTN in either group. In both, transdermal GTN therapy was associated with a significant fall in hematocrit that persisted for the entire treatment period. Hydralazine had no effect on this response. These data suggest that hydralazine therapy does not prevent loss of systemic arterial effects or prevent plasma volume expansion during sustained transdermal GTN therapy.
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PMID:The effect of hydralazine on the development of tolerance to continuous nitroglycerin. 902 1

Vascular tolerance develops rapidly in isolated vascular strips exposed to millimolar concentrations of nitroglycerin. Several mechanisms, including depletion of sulfhydryl groups, reduced biotransformation of nitrates to NO or nitrosothiols, oxygen free radical injury, and downregulation of a membrane-bound enzyme or a nitrate receptor, have been proposed, but the exact mechanism responsible for in-vitro tolerance remains unknown. In-vivo tolerance of the beneficial effects of nitrates on hemodynamics, myocardial ischemia, and exercise performance develops rapidly. It has been suggested, but remains to be proven, that development of venous tolerance and not arterial tolerance is responsible for the attenuation of nitrate effects during long-term nitrate therapy. Several mechanisms, including neurohormonal activation, depletion of sulfhdryl groups, and the shift of fluid from the extravascular to intravascular compartment have been implicated. However, the use of agents to counteract these mechanisms (ACE inhibitors, sulfhydryl donors, diuretics) has produced conflicting results. Thus, at present the mechanism responsible for in vivo tolerance to nitrates remains unknown. Both in vitro and in vivo vascular tolerance to nitrates can be prevented or minimized by providing nitrate-free or low-nitrate intervals. However, during nitrate-free periods, rebound phenomena (rest angina in patients with ischemic heart disease or a deterioration in exercise performance prior to the renewal of the morning dose in patients with stable angina) remain a clinical concern. When treating patients with stable angina pectoris, it must be recognized that none of the nitrate preparations or formulations can provide round-the-clock antianginal or antiischemic prophylaxis. In these patients, beneficial antianginal and antiischemic effects of nitrates for 10-14 hours during the daytime can be maintained by using formulations and dosing regimens that avoid or minimize the development of tolerance (standard formulation of isosorbide-5-mononitrate, 20 mg in the morning and 7 hours later; slow-release formulation of isosorbide-5-mononitrate, 120-240 mg once a day; or nitroglycerin patch delivering 0.6 nitroglycerin per hour for 10-12 hours each day). Only the patch on and off treatment is associated with nitrate rebound. Although intermittent nitrate therapy is not associated with the development of tolerance, this strategy cannot be recommended for treating unstable angina because rebound angina during nitrate-free periods complicates clinical decision making. In the acute phase of unstable angina, continuous treatment with intravenous nitroglycerin is recommended because it permits rapid up- or down-titration. Tolerance towards antianginal and antiischemic effects does develop in a substantial number of patients with 24 hours, but this can be overridden by dose escalation and restoration of the therapeutic effectiveness of nitroglycerin. Tolerance towards the beneficial effects of nitrates on hemodynamics and on exercise performance also develops rapidly during continuous or long-term nitrate therapy, and for these reasons nitrates are not used as first-line therapy to treat chronic heart failure. In combination with hydralazine, high-dose isosorbide dinitrate (30-40 mg four times a day) improves survival, but this combination therapy is inferior to ACE inhibitors.
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PMID:Nitrate tolerance, rebound, and their clinical relevance in stable angina pectoris, unstable angina, and heart failure. 911 Jan 17

Nisoldipine coat-core is an extended-release once-daily formulation of a dihydropyridine calcium antagonist effective in the treatment of chronic stable angina pectoris. With immediate-release formulations of nisoldipine, plasma drug concentrations that produce therapeutic effects result rapidly, but are not sustained and do not maintain the effects throughout a 12-hour dosage interval. In contrast, with nisoldipine coat-core, a gradual increase in plasma nisoldipine concentrations occurs over 12 hours and therapeutic concentrations are then maintained for the duration of a 24-hour dosage interval. In dosages of 10 to 60 mg once daily, nisoldipine coat-core controls symptoms of angina and improves exercise-induced signs of ischaemia in patients with stable angina. Compared with placebo, daily nisoldipine coat-core doses of > or = 20 mg provide statistically significant increases in total exercise time and time to produce angina and a trend towards an increase in the time to produce 1 mm ST segment depression, in exercise tests conducted approximately 23 hours postdose. When administered in 20 and 40 mg daily doses, nisoldipine coat-core produces improvements in exercise test parameters that are similar to those seen with amlodipine 5 or 10 mg/day or regular-release or sustained-release (SR) diltiazem 240 mg/day. The frequency of daily angina attacks and consumption of short-acting nitrates are also reduced by nisoldipine to a similar extent to that observed with these other agents. After longer term (1 year) administration of 10 to 60 mg daily, improvements in exercise test parameters are maintained, with equivalent anti-ischaemic efficacy seen in patients receiving nisoldipine coat-core alone or with background nitrate or beta-blocker therapy. Adverse events associated with nisoldipine coat-core are typical of the dihydropyridine class of calcium antagonists, with peripheral oedema and headache being most common. Nisoldipine coat-core appears to be associated with fewer deaths than placebo, notably in the DEFIANT-II (Doppler Flow and Echocardiography in Functional Cardiac Insufficiency: Assessment of Nisoldipine Therapy II) study, where only 1 death occurred with nisoldipine compared with 7 in the placebo group. Nisoldipine should not be taken during phenytoin therapy. In addition, grapefruit juice should be avoided during nisoldipine therapy and nisoldipine should not be taken concurrently with high-fat meals. Thus, the coat-core formulation of nisoldipine appears to have overcome the limitations of the shorter duration of action of immediate-release nisoldipine. Nisoldipine coat-core is well tolerated and once-daily administration produces a long duration of effective anti-ischaemic relief in patients with chronic stable angina pectoris.
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PMID:Nisoldipine coat-core. A review of its pharmacodynamic and pharmacokinetic properties and clinical efficacy in the management of ischaemic heart disease. 912 71

The predominant venodilator properties of the nitrates and their augmentation of collateral coronary blood flow to the ischemic myocardium endows them with some ideal characteristics for treating myocardial ischemic syndromes. Additional efficacy stems from the ability of the nitrates to replenish the deficient endothelium-derived relaxing factor (EDRF), nitric oxide (NO), in patients with coronary heart disease and also to inhibit platelet aggregation. In stable angina pectoris, the antianginal and antiischemic effects of oral nitrates are well established. Continuous administration of nitrates may lead to tolerance of their clinical efficacy. Recent studies, however, have demonstrated that when used in recommended doses, tolerance can be avoided during long-term treatment with oral nitrates without provocation of anginal attacks during periods of low nitrate levels at night and early hours of the morning. Thus, prolonged treatment with an asymmetric twice-daily regimen of immediate-release isosorbide-5-mononitrate in patients with stable angina pectoris does not give rise to clinical tolerance, prolongs exercise duration, and delays the onset of myocardial ischemia. In unstable angina pectoris, nitrates rapidly relieve chest pain and ameliorate the electrocardiographic signs of myocardial ischemia. In patients with acute myocardial infarction, early treatment with nitrates prevents left ventricular dilatation, improves pumping function, and reduces the risk of ventricular arrhythmias. In patients with chronic heart failure, oral nitrates improve exercise tolerance and, when given in combination with the systemic arterial dilator hydralazine, extend survival. Meta-analysis of published studies has demonstrated that both intravenous and oral nitrates reduced infarct size and morbidity and mortality in patients with acute myocardial infarction. In the ISIS 4 post-infarction study, isosorbide-5-mononitrate 60 mg once daily was not superior to placebo in reducing mortality risk. However, in the GISSI 3 study, the combination of nitrates with an angiotensin-converting enzyme (ACE) inhibitor reduced mortality risks by 17% in patients with acute myocardial infarction. In both the ISIS 4 and GISSI 3 studies, 62% and 57% of the patients in the placebo and control groups, respectively, were treated with nitrates for control of rest angina, myocardial ischemia, and or left ventricular failure symptoms, and this widespread use of open-label nitrates in the control groups may have diluted the true beneficial effects of nitrates in both studies. Taken together, these many studies with oral nitrate treatment in coronary heart disease and heart failure clearly emphasize that these drugs are safe and play more than a symptomatic role in the management of patients with acute and chronic ischemic syndromes due to coronary artery disease.
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PMID:Oral nitrates: more than symptomatic therapy in coronary artery disease? 921 Oct 13

Alterations in nitric oxide (NO) biosynthesis in the heart have been implicated in the pathophysiology of heart failure. We compared changes in cardiac nitric oxide synthase (NOS) activity and expression in genetically heart failure-prone (SHHF) rats at 6, 12, and 18 mo of age with those in age-matched spontaneously hypertensive (SHR) and Sprague-Dawley (SD) rats. Systolic blood pressure was significantly higher in SHHF and SHR rats compared with SD rats; however, it declined with age in SHHF rats only. Left ventricular mass increased with age in SHR and SHHF, but not in SD rats. Plasma nitrate and nitrite level was elevated in SHHF and SHR rats at 18 mo only. In left ventricular homogenates from SHHF rats, Ca(2+)-dependent NOS activity increased markedly with age and was accompanied by enhanced expression of endothelial NOS (eNOS). In contrast, SHR rats showed a much smaller increase in Ca(2+)-dependent NOS activity over time without changes in eNOS expression; neither parameter was altered with age in SD rats. Ca(2+)-independent NOS activity was not detected in any heart. This is the first report of a unique alteration in myocardial NOS activity in hypertensive rats genetically prone to heart failure.
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PMID:Age-dependent augmentation of cardiac endothelial NOS in a genetic rat model of heart failure. 932 10

The goal of this study was to understand the mechanisms behind the changes in plasma NOx during heart failure. Heart failure is associated with an increase in plasma nitrate levels, and yet most experimental evidence demonstrates a reduction in endothelial nitric oxide production during heart failure. Dogs were chronically instrumented for measurement of systemic hemodynamics and left ventricular (LV) dimensions. Hearts were paced at 210 bpm for 3 weeks (n = 14) and then 240 bpm for 1 week (n = 7). Hemodynamics, arterial blood gases, plasma NOx, and creatinine levels were monitored weekly. Heart failure was evidenced by cachexia, ascites, and hemodynamic alterations. Resting heart rate rose (94 +/- 6 to 135 +/- 9 bpm), and LV dP/dt fell (2810 +/- 82 to 1471 +/- 99 mm Hg/s), while LV end diastolic pressure quadrupled (5.8 +/- 0.7 to 25 +/- 0.8 mm Hg), and diastolic wall stress quadrupled (11 +/- 1.3 to 43 +/- 6.0 g/cm2, all P < 0.05). These changes occurred during a doubling in plasma NOx (5.5 +/- 1.5 to 10 +/- 1.6 microM, P < 0.05). There were no changes in plasma NOx through 3 weeks of pacing. Plasma creatinine levels increased 450% (from 0.27 +/- 0.32 to 1.21 +/- 0.63 mg%). Stimulated nitrite production by agonists in sieved coronary microvessels was unchanged after 3 weeks of pacing but was reduced after heart failure. Plasma NOx did not correlate with LV dP/dt or systolic wall stress but correlated directly with LV EDP or diastolic wall stress and inversely with cardiac work. Plasma NOx rose in direct relation to plasma creatinine levels (Y = 4.8X + 2.8, r2 = 0.84), suggesting that the rise in plasma NOx during heart failure is due to decreased renal function not increased NO production.
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PMID:Mechanisms of nitrate accumulation in plasma during pacing-induced heart failure in conscious dogs. 944 9

Since the classical studies by Furchgott and Zawadski (Nature, 1980, 286, 373-376), the vascular endothelium is known to play a fundamental role in the regulation of haemostasis and vasomotor activity. This is primarily due to its strategic interface position between the circulating blood and smooth muscle cells of the media. Due to the presence of specific receptors to mediators released during platelet aggregation (thrombin, ATP, serotonin, PAF, etc.), and the presence of mechanoreceptors sensitive to shearing forces generated by blood flow along the vessel wall, the endothelium is able to release, at the two poles of the cell, vasodilator and antiaggregant substances called "endothelium derived relaxing factors" (EDRFs), the best known for which are nitric oxide (NO) ans prostacyclin (PGl2). In the absence of endothelium (angioplasty), or in the case of endothelium dysfunction related to cardiovascular diseases such as hypertension, heart failure, atherosclerosis or diabetes, EDRF synthesis is absent or defective and its oxidative catabolism in increased (particularity by superoxide anion), resulting in varying degrees of disorders of haemostasis (thrombosis) and/or arterial and venous vasomotor activity. The only known effective treatment to palliate these dysfunctions is exogenous NO, supplied in the form of nitrate (nitroglycerin, isosorbide dinitrate, 5-mononitrate) or "NO donors" (Sin1, nitroprussate). The advantage of these substances is that their vasodilator effects (and, in some cases, their antiaggregant effects) are strictly endothelium-independent and they remain effective regardless of the causes and severity of endothelial dysfunction.
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PMID:[Nitrates and coronary vascular endothelium dysfunction]. 945 72


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