Comparative hemodynamic effects of inotropic and vasodilator drugs in severe heart failure

Estimation of Left Ventricular End-Systolic Elastance From Brachial Pressure Waveform via Deep Learning

Determination of left ventricular (LV) end-systolic elastance (E es ) is of utmost importance for assessing the cardiac systolic function and hemodynamical state in humans. Yet, the clinical use of E es is not established due to the invasive nature and high costs of the existing measuring techniques. The objective of this study is to introduce a method to assess cardiac contractility, using as a sole measurement an arterial blood pressure (BP) waveform. Particularly, we aim to provide evidence on the potential in using the morphology of the brachial BP waveform and its time derivative for predicting LV E es via convolution neural networks (CNNs). The requirement of a broad training dataset is addressed by the use of an in silico dataset (n = 3,748) which is generated by a validated one-dimensional mathematical model of the cardiovasculature. We evaluated two CNN configurations: 1) a one-channel CNN (CNN1) with only the raw brachial BP signal as an input, and 2) a two-channel CNN (CNN2) using as inputs both the brachial BP wave and its time derivative. Accurate predictions were yielded using both CNN configurations. For CNN1, Pearson's correlation coefficient (r) and RMSE were equal to 0.86 and 0.27 mmHg/ml, respectively. The performance was found to be greatly improved for CNN2 (r = 0.97 and RMSE = 0.13 mmHg/ml). Moreover, all absolute errors from CNN2 were found to be less than 0.5 mmHg/ml. Importantly, the brachial BP wave appeared to be a promising source of information for estimating E es . Predictions were found to be in good agreement with the reference E es values over an extensive range of LV contractility values and loading conditions. Therefore, the proposed methodology could be easily transferred to the bedside and potentially facilitate the clinical use of E es for monitoring the contractile state of the heart in the real-life setting.

Inotropes in Patients with Advanced Heart Failure: Not Only Palliative Care

Patients with advanced heart failure suffer from severe and persistent symptoms, often not responding disease-modifying drugs, a marked limitation of functional capacity and poor quality of life that can ameliorate with inotropic drugs therapy. In small studies, pulsed infusions of classical inotropes (ie, dobutamine and milrinone) are associated with improvement in hemodynamic parameters and quality of life in patients with advanced heart failure. However, because of the adverse effects of these drugs, serious safety issues have been raised. Levosimendan is a calcium-sensitizing inodilators with a triple mechanism of action, whose infusion results in hemodynamic, neurohormonal, and inflammatory cytokine improvements in patients with chronic advanced HF. In addition, levosimendan has important pleiotropic effects, including protection of myocardial, renal, and liver cells from ischemia-reperfusion injury, and anti-inflammatory and antioxidant effects; these properties possibly make levosimendan an "organ protective" inodilator. In clinical trials and real-world evidence, infusion of levosimendan at fixed intervals is safe and effective in patients with advanced HF, alleviating clinical symptoms, reducing hospitalizations, and improving the quality of life. Therefore, the use of repeated doses of levosimendan could represent the therapy of choice as a bridge to transplant/left ventricular assist device implantation or as palliative therapy in patients with advanced heart failure.

Wireless, Skin-Interfaced Devices for Pediatric Critical Care: Application to Continuous, Noninvasive Blood Pressure Monitoring

Indwelling arterial lines, the clinical gold standard for continuous blood pressure (BP) monitoring in the pediatric intensive care unit (PICU), have significant drawbacks due to their invasive nature, ischemic risk, and impediment to natural body movement. A noninvasive, wireless, and accurate alternative would greatly improve the quality of patient care. Recently introduced classes of wireless, skin-interfaced devices offer capabilities in continuous, precise monitoring of physiologic waveforms and vital signs in pediatric and neonatal patients, but have not yet been employed for continuous tracking of systolic and diastolic BP-critical for guiding clinical decision-making in the PICU. The results presented here focus on materials and mechanics that optimize the system-level properties of these devices to enhance their reliable use in this context, achieving full compatibility with the range of body sizes, skin types, and sterilization schemes typically encountered in the PICU. Systematic analysis of the data from these devices on 23 pediatric patients, yields derived, noninvasive BP values that can be quantitatively validated against direct recordings from arterial lines. The results from this diverse cohort, including those under pharmacological protocols, suggest that wireless, skin-interfaced devices can, in certain circumstances of practical utility, accurately and continuously monitor BP in the PICU patient population.

The effect of left ventricular contractility on arterial hemodynamics: A model-based investigation

Ventricular-arterial coupling is a major determinant of cardiovascular performance, however, there are still inherent difficulties in distinguishing ventricular from vascular effects on arterial pulse phenotypes. In the present study, we employed an extensive mathematical model of the cardiovascular system to investigate how sole changes in cardiac contractility might affect hemodynamics. We simulated two physiologically relevant cases of high and low contractility by altering the end-systolic elastance, E_es, (3 versus 1 mmHg/mL) under constant cardiac output and afterload, and subsequently performed pulse wave analysis and wave separation. The aortic forward pressure wave component was steeper for high E_es, which led to the change of the total pressure waveform from the characteristic Type A phenotype to Type C, and the decrease in augmentation index, AIx (-2.4% versus +18.1%). Additionally, the increase in E_es caused the pulse pressure amplification from the aorta to the radial artery to rise drastically (1.86 versus 1.39). Our results show that an increase in cardiac contractility alone, with no concomitant change in arterial properties, alters the shape of the forward pressure wave, which, consequently, changes central and peripheral pulse phenotypes. Indices based on the pressure waveform, like AIx, cannot be assumed to reflect only arterial properties.

Pediatric Cardiac Intensive Care Society 2014 Consensus Statement: Pharmacotherapies in Cardiac Critical Care Treatment of Acute Heart Failure

OBJECTIVES

To provide an evidence-based review of pharmacotherapies to treat acute heart failure. To accomplish this objective, we will discuss circulatory physiology, vasoactive agents, and their indications in the management of acute heart failure.

DATA SOURCE

A MEDLINE-baseline review of the literature.

CONCLUSIONS

The optimal selection of vasoactive agents requires a consideration of circulatory physiology and the tailored application of pharmacotherapies to treat patients with acute heart failure.

Phosphodiesterase III inhibitors for heart failure

BACKGROUND

In the treatment of chronic heart failure, vasodilating agents, ACE inhibitors and beta-blockers have shown an increase of life expectancy. Another strategy is to increase the inotropic state of the myocardium : phosphodiesterase inhibitors (PDIs) act by increasing intra-cellular cyclic AMP, thereby increasing the concentration of intracellular calcium, and lead to a positive inotropic effect.

OBJECTIVES

This overview on summarised data aims to review the data from all randomised controlled trials of PDIs III versus placebo in symptomatic patients with chronic heart failure. The primary endpoint is total mortality. Secondary endpoints are considered such as cause-specific mortality, worsening of heart failure (requiring intervention), myocardial infarction, arrhythmias and vertigos. We also examine whether the therapeutic effect is consistent in the subgroups based on the use of concomitant vasodilators, the severity of heart failure, and the type of PDI derivative and/or molecule. This overview updates our previous meta-analysis published in 1994.

SEARCH STRATEGY

Randomised trials of PDIs versus placebo in heart failure were searched using MEDLINE (1966 to 2004 January), EMBASE (1980 to 2003 December), Cochrane CENTRAL trials (The Cochrane Library Issue 1, 2004) and McMaster CVD trials registries, and through an exhaustive handsearching of international abstracting publications (abstracts published in the last 22 years in the "European Heart Journal", the "Journal of the American College of Cardiology" and "Circulation").

SELECTION CRITERIA

All randomised controlled trials of PDIs versus placebo with a follow-up duration of more than three months.

DATA COLLECTION AND ANALYSIS

21 trials (8408 patients) were eligible for inclusion in the review. 4 specific PDI derivatives and 8 molecules of PDIs have been considered.

MAIN RESULTS

As compared with placebo, treatment with PDIs was found to be associated with a significant 17% increased mortality rate (The relative risk was 1.17 (95% confidence interval 1.06 to 1.30; p<0.001). In addition, PDIs significantly increase cardiac death, sudden death, arrhythmias and vertigos. Considering mortality from all causes, the deleterious effect of PDIs appears homogeneous whatever the concomitant use (or non-use) of vasodilating agents, the severity of heart failure, the derivative or the molecule of PDI used.

AUTHORS' CONCLUSIONS

Our results confirm that PDIs are responsible for an increase in mortality rate compared with placebo in patients suffering from chronic heart failure. Currently available results do not support the hypothesis that the increased mortality rate is due to additional vasodilator treatment. Consequently, the chronic use of PDIs should be avoided in heart failure patients.

Carnitine palmitoyltransferase-I, a new target for the treatment of heart failure: perspectives on a shift in myocardial metabolism as a therapeutic intervention

Although the heart is capable of extracting energy from different types of substrates such as fatty acids and carbohydrates, fatty acids are the preferred fuel under physiological conditions. In view of the presence of diverse defects in myocardial metabolism in the failing heart, changes in metabolism of glucose and fatty acids are considered as viable targets for therapeutic modification in the treatment of heart failure. One of these changes involves the carnitine palmitoyltransferase (CPT) enzymes, which are required for the transfer of long chain fatty acids into the mitochondrial matrix for oxidation. Since CPT inhibitors have been shown to prevent the undesirable effects induced by mechanical overload, e.g. cardiac hypertrophy and heart failure, it was considered of interest to examine whether the inhibition of CPT enzymes represents a novel approach for the treatment of heart disease. A shift from fatty acid metabolism to glucose metabolism due to CPT-I inhibition has been reported to exert beneficial effects in both cardiac hypertrophy and heart failure. Since the inhibition of fatty acid oxidation is effective in controlling abnormalities in diabetes mellitus, CPT-I inhibitors may also prove useful in the treatment of diabetic cardiomyopathy. Accordingly, it is suggested that CPT-I may be a potential target for drug development for the therapy of heart disease in general and heart failure in particular.

Low-dose dobutamine stress 99mTc tetrofosmin quantitative gated SPECT performed during the acute phase of myocardial infarction predicts subsequent myocardial viability and detects stunned myocardium

This study evaluated the ability of low-dose dobutamine stress 99mTc tetrofosmin (DSTF) quantitative gated single photon emission computed tomography (QGS) performed during the acute phase of myocardial infarction to predict subsequent myocardial viability and detect stunned myocardium. Twenty-four patients suffering their first acute myocardial infarction (AMI) underwent coronary angioplasty after coronary angiography (CAG) immediately following admission. Follow-up CAG and left ventriculography (LVG) were performed 10 days and 6 months later. All patients underwent DSTF QGS to measure left ventricular ejection fraction (LVEF) at rest and during dobutamine infusion (10 microg.kg(-1).min(-1)) 14 days after angioplasty. No patient suffered coronary restenosis. After 6 months, the LVEF measured by LVG improved >5% in 12 patients (group A), and did not improve in the remaining 12 patients (group B). The culprit coronary artery, the peak serum creatine phosphokinase concentration, the recanalization time, and the LVEF during the acute phase were similar in the two groups. However, the increase in the LVEF was greater in group A than in group B during dobutamine infusion (deltaLVEF) as measured by DSTF QGS (11.2+/-3.8% vs 2.9+/-4.7%, P <0.001). If a cut-off value of 6.5% for the deltaLVEF was used to predict the improvement in LVEF during the chronic phase, then the sensitivity of this test was 83.3% and its specificity was 83.3%. It is concluded that DSTF QGS during AMI can be used to predict myocardial viability and detect stunned myocardium.

Dobutamine gated blood pool scintigraphy predicts the improvement of cardiac sympathetic nerve activity, cardiac function, and symptoms after treatment in patients with dilated cardiomyopathy

BACKGROUND

We evaluated whether dobutamine gated blood pool scintigraphy (DOB-GBP) can predict improvement in cardiac sympathetic nerve activity and cardiac function after beta-blocker therapy in patients with dilated cardiomyopathy (DCM).

METHODS AND RESULTS

Twenty-two patients with DCM underwent DOB-GBP to measure left ventricular ejection fraction (LVEF) at rest, and during 5, 10, and 15 microg/kg/min of dobutamine infusion before therapy. Examinations were performed before and after 1 year of therapy. The heart/mediastinum count (H/M) ratio and total defect score (TDS) were determined for 123I-meta-iodobenzylguanidine images from anterior planar image and single-photon emission CT images. LVEF and left ventricular end-diastolic dimension (LVDd) were determined by echocardiography. After 1 year of treatment, the echocardiographic LVEF improved > 5% in 11 patients (group A), but did not improve in the remaining 11 patients (group B). Before treatment, TDS, H/M, LVEF, and LVDd were similar in both groups. However, there was a greater increase in the LVEF during dobutamine infusion in group A than in group B (21 +/- 8% vs 9 +/- 3%, p < 0.001). If a critical value of 15% for the DeltaLVEF was used to predict the improvement in LVEF after treatment, the sensitivity was 91% and specificity was 82%. The TDS, H/M ratio, LVDd, and New York Heart Association functional class improved in group A to a greater extent than in group B.

CONCLUSIONS

DOB-GBP can be used to predict improved cardiac sympathetic nerve activity, cardiac function, and symptoms after treatment in patients with DCM.

Increases in inotropic state without change in heart rate: combined use of dobutamine and zatebradine in conscious dogs

The cardiovascular and left ventricular functional effects of dobutamine (5, 10 and 20 micrograms kg-1 min-1) were examined in conscious, chronically instrumented dogs in the presence and absence of control of heart rate with the specific bradycardic agent, zatebradine. Dobutamine increased heart rate, cardiac output, stroke volume, diastolic coronary blood flow velocity and pressure-work index (calculated myocardial oxygen consumption) and decreased systemic vascular resistance and diastolic coronary vascular resistance. Mean arterial pressure and left ventricular systolic and end-diastolic pressures were unchanged. Dobutamine-induced increases in heart rate and pressure-work index were attenuated by zatebradine. Dobutamine alone increased preload recruitable stroke work slope (63 +/- 6 to 116 +/- 11 mmHg) and +dP/dt. These positive inotropic effects were unaffected by zatebradine. Dobutamine decreased the time constant of isovolumic relaxation (30 +/- 3 to 25 +/- 2 ms). Dobutamine-induced decreases in the time constant of isovolumic relaxation were not altered by zatebradine, indicating that changes in the time constant occurred independent of heart rate. Dobutamine also increased the maximal segment lengthening velocity to a similar degree in zatebradine-treated versus untreated dogs. Control of dobutamine-induced tachycardia by zatebradine decreases myocardial oxygen consumption but does not alter the positive inotropic and lusitropic effects of dobutamine.

Refractory Heart Failure: A Therapeutic Approach

Optimal “triple therapy” for patients with chronic congestive heart failure (CHF) includes diuretics, digoxin, and either angiotensin-converting enzyme inhibitors or hydralazine plus nitrates. Refractory CHF is defined as symptoms of CHF at rest or repeated exacerbations of CHF despite “optimal” triple-drug therapy. Most patients with refractory CHF require hemodynamic monitoring and treatment in the intensive care unit. If easily reversible causes of refractory CHF cannot be identified, then more aggressive medical and surgical interventions are necessary. The primary goal of intervention is to improve hemodynamics to palliate CHF symptoms and signs (i.e., dyspnea, fatigue, edema). Secondary goals include improved vital organ and tissue perfusion, discharge from the intensive care unit, and, in appropriate patients, bridge to cardiac transplantation. Medical interventions include inotropic resuscitation (e.g., adrenergic agents, phosphodiesterase inhibitors, allied nonglycoside inodilators), load resuscitation (e.g., afterload and preload reduction with nitroprusside or nitroglycerin; preload reduction with diuretics and diuretic facilitators, such as dopaminergic agents or ultrafiltration), and electrical resuscitation (e.g., prevention of sudden death, correction of new or rapid atrial fibrillation, or dual chamber pacing in the setting of relative prolongation of the PR interval and diastolic mitral/tricuspid regurgitation). Surgical interventions are temporizing (e.g., intra-aortic balloon pump and other mechanical assist devices) or definitive (e.g., coronary artery revascularization, valvular surgery, and cardiac transplantation). Although these interventions may improve immediate survival in the short term, only coronary artery revascularization and cardiac transplantation have been shown to improve long-term survival.

Molecular genetics: cardiac disease and risk-related genes

Molecular genetics is playing an increasing role in the diagnosis, treatment, and prevention of cardiac disease. Moreover, most of the genes that may cause cardiac disease or predispose an individual to cardiac disease are anticipated to be identified within the next 10 years. Several genes with risk for heart disease have been identified, such as the ACE genotype DD. Replacement gene therapy as well as use of promoter-specific drugs to act on genetic regulatory elements will encompass the future treatment of cardiovascular disease. This article provides a summary of the potential roles of genetic screening for cardiac risk factors and genetic interventions in cardiovascular disease.

Hemodynamic responses to dobutamine during acute normovolemic hemodilution

The effects of dobutamine (DOB) on myocardial performance, systemic hemodynamics, and oxygen delivery during acute normovolemic hemodilution in anesthetized rats were studied. Forty-two Sprague Dawley rats (body weight 375 to 425 g) were divided into six equal groups. Hemodynamic and cardiac indices were measured or calculated at baseline, 30 minutes after the initiation of hemodilution (HD), and 15 minutes after DOB or saline infusion. Myocardial performance in response to acute pressure or volume loads was studied in all groups of animals. HD to a hematocrit (Hct) value of 20% resulted in no change in heart rate (HR), increased CI, SVI, and LV dP/dt, and decreased MAP, SVRI, and oxygen delivery index (O2DI). HD increased peak SV and CI after preload stress while the left ventricular developed pressure (LVDP) was unchanged. Infusion of DOB as 7.5 or 15 micrograms/kg/min increased HR, CI, and LV dP/dt as well as LVDP. At the same time, DOB decreased MAP and SVR, whereas the SVI remained unchanged. In non-HD animals both doses of DOB increased LVDP, but only the larger dose increased CI, whereas peak SV decreased with the smaller dose. Arterial carbon dioxide tension (PaCO2) increased, whereas pH and arterial oxygen tension (PaO2) decreased; however, O2DI remained unchanged. Concomitant hemodilution and DOB infusion resulted in attenuation of HR response to DOB, exaggerated the drop in MAP and SVR, and increased LV dP/dt. Only the larger dose of DOB increased the CI, whereas neither dose could alter the SVI in HD animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of flosequinan (BTS 49465) on myocardial oxygen consumption

BTS 49465 (flosequinan), a putative selective, balanced arterial and venous vasodilator, displays positive inotropic effects in doses lower than those producing vasodilation. Thus rather than unloading the myocardium, flosequinan may increase myocardial work and oxygen consumption (MVO2), and may adversely affect the patient with myocardial ischemia or compromised coronary blood flow. This study compared the effects of flosequinan with milrinone, a mixed positive inotropic agent and vasodilator, and with nitroprusside (SNP), a standard direct-acting vasodilator, on myocardial dP/dT, MVO2, and myocardial energetics in the normal pentobartital-anesthetized dog. The effect of flosequinan on myocardial work was also evaluated in the dog with propranolol-induced heart failure (PIHF). Fifteen minutes after intraduodenal (id) administration of flosequinan (0.3, 1.0, and 3.0 mg/kg) to seven dogs, mean myocardial dP/dT was increased by 11%, 27%, and 54%, respectively, whereas stroke MVO2 was increased by 10%, 24%, and 47%, respectively. Doses of flosequinan greater than 0.3 mg/kg decreased left ventricular (LV) work but LV efficiency decreased in a dose-related manner. Milrinone (0.1, 0.3, and 1.0 mg/kg, id) increased LV dp/dt by 34%, 68%, and 104% above basal values, while increasing stroke MVO2 by 24%, 106%, and 249%, respectively (n = 7). LV work and LV efficiency decreased after each dose of milrinone. SNP (0.001, 0.003, and 0.01 mg/kg/min, intravenously) did not increase dP/dT but decreased LV work by 28%, 42%, and 46% (n = 5). In animals with PIHF, flosequinan (1 and 3 mg/kg, id) increased LV dP/dT 58% and 87% and increased LV work by 58% and 76% above control values. It was concluded that (1) flosequinan is a positive inotropic agent as well as a vasodilator; (2) in the normal animal the energy cost of positive inotropic activity is less with flosequinan than with milrinone, despite the lesser vasodilating action of the former; and (3) in the animal with a depressed myocardium, flosequinan may adversely affect myocardial work and wall tension.

Effect of dobutamine on skeletal muscle metabolism in patients with congestive heart failure

Dobutamine is known to increase leg blood flow during exercise in patients with heart failure. However, it is uncertain whether the increased flow is delivered to working skeletal muscle. In 7 patients with heart failure, the effects of dobutamine were examined on calf phosphorus-31 magnetic resonance spectroscopy (MRS) spectra and femoral vein blood flow during rest and upright plantar flexion. During upright plantar flexion every 3 seconds, dobutamine increased femoral venous blood flow (control 1.7 +/- 0.1; dobutamine 2.1 +/- 1.0 liters/min; p less than 0.05) and increased femoral venous O2 saturation (control 24 +/- 5%; dobutamine 31 +/- 2%; p less than 0.05), indicating improved total leg blood flow. However, dobutamine did not change the slope of the relation between systemic VO2 and the calf inorganic phosphate to phosphocreatine relation (control 0.0054 +/- 0.0039; dobutamine 0.0056 +/- 0.0032; difference not significant) and did not change muscle pH, suggesting no improvement in blood flow to active skeletal muscle. These findings suggest that dobutamine does not improve oxygen delivery to working skeletal muscle in patients with heart failure, despite its ability to increase cardiac output and limb blood flow.

Dobutamine: ten years later

Dobutamine is a commonly used positive inotrope for the short-term management of heart failure. It is commercially available as a 50:50 mixture of two isomers with unique effects on alpha- and beta adrenergic receptors. In dosages of 2-15 micrograms/kg/minute, dobutamine has been shown to increase cardiac output (mainly through stroke volume), reduce systemic vascular resistance, lower central venous and pulmonary artery wedge pressures, improve renal blood flow, and relieve signs and symptoms of congestive heart failure. At higher dosages it can increase heart rate and induce arrhythmias. Recent evidence indicates that effects of dobutamine last long after the drug has been eliminated from the plasma, and some work has been done on ambulatory use of this agent. Dobutamine has been used successfully in several circumstances, such as after cardiac surgery, in patients with myocardial infarction, and in various shock states. An understanding of the pathophysiology of the underlying disorder is important in deciding which catecholamine to use. With this in mind, monotherapy or combination therapy with inodilators such as dobutamine, or inopressors like dopamine will follow logically.

Synergistic effect of captopril and dobutamine on left ventricular pressure-volume and pressure-shortening relations in severe cardiac failure

The acute effects of captopril and dobutamine, alone and in combination, on left ventricular contractility were assessed from left ventricular end-systolic pressure-volume and pressure-shortening relations in 6 patients with severe end-stage cardiac failure. Dobutamine was given by constant intravenous infusion on two occasions 48 hours apart, on one of these occasions the patient also received oral captopril in a dose of 37 +/- 12 mg 6-hourly. Pressures and cardiac index were measured, and left ventricular volumes and ejection fraction computed from simultaneously recorded radionuclide ventriculography. Dobutamine alone did not cause a statistically significant increase in stroke index, stroke work index, cardiac index and ejection fraction, although pulmonary capillary wedge pressure and right atrial pressure fell (P less than 0.05). There was no change in systemic or pulmonary vascular resistance nor in arterial blood pressure. Following administration of captopril, diastolic arterial pressure decreased (P less than 0.05), and the dobutamine challenge produced a greater and significant rise in stroke and stroke work index (P less than 0.05) and cardiac index (P less than 0.01). The left ventricular contractile state was unaltered by captopril but appeared to increase with dobutamine and more so during combined therapy with captopril and dobutamine, indicating a synergistic effect of the two drugs when given in combination.

Combination of positive inotropic and vasodilating substances in congestive heart failure

Therapy combining vasodilators and inotropic agents is considered to be one of the most powerful means of improving cardiac function in patients with congestive heart failure (CHF). The vasodilators enhance the effectiveness of inotropic agents by providing a reduction in preload and/or afterload. Inotropic drugs with different mechanisms of action, such as digitalis glycosides, ephedrine, dopamine, dobutamine, ibopamine, terbutaline, salbutamol, pirbuterol, prenalterol, amrinone, and milrinone, have been tested in combination with vasodilators with a predominant effect on preload (nitrates, molsidomine), with a predominant effect on afterload (hydralazine, nifedipine), or with a balanced action on both arterial and venous beds (nitroprusside, prazosin, captopril), showing positive results. The problem of the combination of digitalis glycosides and vasodilators with different sites of action has been considered by our group. In 42 patients with CHF, digoxin (DIG, 0.01 mg/kg intravenously) was tested in combination with molsidomine (MLS, 4 mg sublingually) (12 patients), a nitrate-like agent with a predominant vasodilating action on the capacitance vessels, nifedipine (NFP, 10 mg sublingually) (22 patients), a Ca2+ antagonist drug with a predominant action on the resistance vessels, and captopril (CPT, 25 mg orally) (8 patients), an ACE inhibitor with a balanced effect on both preload and afterload. The combination DIG plus MLS caused a reduction in left ventricular filling pressure (LVFP) greater than that achieved with either agent alone. The hemodynamic improvement was obtained without side effects, in spite of the striking fall in preload. We stress that this investigation was performed on patients with CHF following acute myocardial infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

Sustained hemodynamic improvement during long-term therapy with levodopa in heart failure: role of plasma catecholamines

Long-term therapy with oral sympathomimetic amines in patients with heart failure has been limited by the eventual development of diminished pharmacologic efficacy. However, a previous investigation in five subjects with heart failure suggested that long-term ingestion of levodopa, which is decarboxylated endogenously to dopamine, produces a sustained improvement in cardiac function. In the present study, levodopa was administered orally (1.5 to 2.0 g) to 14 patients with heart failure while hemodynamic responses and plasma catecholamines were monitored. Initially, an increase in cardiac index and stroke volume index was accompanied by a decline in systemic vascular resistance, mean pulmonary capillary wedge pressure and mean right atrial pressure. Heart rate and mean arterial pressure were unchanged. Plasma concentrations of dopamine rose substantially after drug ingestion and correlated significantly with changes in cardiac index (r = 0.73, p less than 0.05). After 12 weeks of treatment with levodopa, the changes in cardiac index, stroke volume index, systemic vascular resistance and plasma dopamine levels persisted (n = 12 patients). Moreover, a significant decrease occurred in the heart rate at rest. Although there was an initial tendency for plasma norepinephrine concentrations to increase, a return to control levels was documented after long-term treatment. Thus, tolerance to the hemodynamic actions of levodopa did not develop during long-term administration of the drug. The hemodynamic responses observed can be ascribed to the activation of beta 1-adrenoceptors and dopamine1 receptors by dopamine generated from levodopa. The dopamine2 activity of dopamine does not appear to be responsible for the improvement in cardiac performance produced by levodopa.

The pharmacology of dobutamine

Dobutamine is a sympathomimetic amine that was designed as an inotropic agent for use in congestive heart failure. Clinically, dobutamine increases cardiac output by selectively augmenting stroke volume, and this is associated with a decrease in total peripheral vascular resistance that is mediated, in part, by reflex withdrawal of sympathetic tone to the vasculature. This hemodynamic profile of dobutamine makes the drug of value in the management of low output cardiac failure. The inotropic activity of dobutamine has previously been attributed to selective stimulation of myocardial beta 1-adrenoceptors. However, recent studies from a number of laboratories indicate that the mechanism of action of dobutamine is substantially more complex. Dobutamine has the capacity to stimulate beta 1-, beta 2-, and alpha 1-adrenoceptors in the cardiovascular system at doses that approximate those used clinically. It has recently been suggested that the inotropic activity of dobutamine results from combined beta 1- and alpha 1-adrenoceptor stimulation in the myocardium, and that this activity could explain, at least in part, the inotropic selectivity of the compound. Furthermore, in the vasculature, the beta 2-adrenoceptor-mediated vasodilatory effect of dobutamine is exactly offset by the alpha 1-adrenoceptor-mediated vasoconstrictor activity, such that net changes in blood pressure are minimal following the administration of dobutamine. It is concluded, therefore, that the hemodynamic profile of dobutamine in patients with congestive heart failure is derived from a unique and complex series of interactions with alpha- and beta-adrenoceptors in the cardiovascular system.

A comparison of hemodynamic effects of one-month oral captopril and enoximone treatment for severe congestive heart failure

A double-blind, randomized, crossover trial was undertaken to compare the effect of enoximone (150 mg, 3 times daily) and captopril (25 mg, 3 times daily) added to conventional therapy with diuretics in the treatment of 13 patients with severe chronic heart failure. Each treatment was continued for 1 month. Heart failure was due to idiopathic dilated cardiomyopathy in 6 patients and coronary artery disease in 7. Hemodynamic measurements were made at rest and during exercise, on entry to the study and after each treatment period. The cardiac index at rest was 1.9 +/- 0.2 liters min-1 m2 (mean +/- 1 standard deviation) and did not change with either drug. Systemic vascular resistance at rest decreased with enoximone (p less than 0.05) and was unchanged with captopril. Systemic vascular resistance at peak exercise was not lowered by either drug. Both drugs caused an increase of cardiac index at peak exercise (p less than 0.04) and a prolongation of exercise time (p less than 0.05). No difference was detected between the hemodynamic response to the 2 drugs after 1 month treatment either at rest or during exercise.

Total body oxygen consumption and haemodynamics during the treatment of acute ischaemic heart failure with dopamine and high doses of insulin in dogs

Acute ischaemic left ventricular failure was induced in closed-chest anaesthetized dogs by injection of 50 microns plastic microspheres into the left main coronary artery. This effected a 33% decrease in cardiac output. Dopamine and high doses of insulin restored cardiac output, and these agents in combination raised cardiac output to 34% above pre-ischaemic levels. Total body oxygen consumption was calculated at the various levels of cardiac output, and was found to remain essentially unchanged. Inotropic agents, then, may result in overperfusion with respect to oxygen demand.

Effects of CI-914 in congestive heart failure due to coronary artery disease or idiopathic cardiomyopathy

The hemodynamic effects of CI-914, a phosphodiesterase inhibitor, were studied in 12 patients with left ventricular (LV) dysfunction who were undergoing diagnostic cardiac catheterization. CI-914 was infused intravenously at a rate of 0.8 to 7.0 micrograms/kg/min for 30 to 60 minutes; hemodynamic values were measured every 10 minutes. No effect was seen in the patient receiving 0.8 microgram/kg/min. At infusion rates of 1.2 to 2.4 micrograms/kg/min, cardiac index increased by 14% (p less than 0.025). At infusion rates of 4.5 to 7.0 micrograms/kg/min, cardiac index increased by 21% (n = 8, difference not significant [NS]). Among 4 patients (group B) with an initial pulmonary artery wedge pressure greater than 20 mm Hg and cardiac index less than 2.5 liters/min/m2, cardiac index increased by 50% (p less than 0.001); it did not change among the 4 patients with an initial pulmonary artery wedge pressure of less than 20 mm Hg and cardiac index of more than 2.5 liters/min/m2 (group A). Although systemic vascular resistance decreased in all 8 patients by 26% (p less than 0.01), the reduction was greater in group B (33%, p less than 0.01) than in group A (16%, NS). Peak +dP/dt increased in all 8 patients by 13% (p less than 0.01). Mean stroke work index increased from 29 +/- 15 to 34 +/- 13 g-m/m2; the double product fell from 101 +/- 31 to 91 +/- 23 (NS). In all 12 patients, a linear correlation between peak venous blood concentration and peak effect on cardiac index, systemic vascular resistance and pulmonary artery wedge pressure was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Hemodynamic abnormalities in acute myocardial infarction

Great strides have been made in the management of patients with acute myocardial infarction since the advent of coronary care units. However, congestive heart failure continues to be the major cause of in-hospital mortality. The accurate diagnosis and classification of hemodynamic abnormalities allow the application of specific therapies for each patient. Because clinicians can now routinely measure left and right ventricular preload, systemic and pulmonary vascular resistance, cardiac output, and arteriovenous oxygen difference, pharmacologic and surgical interventions can be applied in a scientific manner. In addition, mechanical complications can be promptly recognized and aggressively treated. Although the mortality rate for patients with severe left ventricular dysfunction after myocardial infarction remains high, expert management offers an improved prognosis for many patients.

Congestive heart failure

A review of the epidemiology, pathophysiology, and treatment of congestive heart failure is presented, with particular attention given to newer modalities of therapy.

Effects of high doses of insulin on systemic haemodynamics and regional blood flows in dogs

This study describes the effects of a wide range of plasma concentrations of insulin on systemic haemodynamics and free fatty acids (FFA) and the effect of a high dose of insulin on regional blood flows in the femoral, carotid, mesenteric and renal arteries. Insulin was infused in 10 dogs at rates of 4, 8, 16, 32, 64 and 128 IU/kg/h, and the experiments were concluded with a bolus injection of 300 IU. Plasma glucose concentrations were kept constant during the experiments. A dose-related increase in maximum rate of left ventricular pressure rise, stroke volume and cardiac output, and decrease in total peripheral resistance was found with insulin infusion rates up to 64 IU/kg/h. Heart rate and mean aortic blood-pressure were unchanged. The maximum antilipolytic effect was obtained at an infusion rate of 16 IU/kg/h. Insulin was given as a bolus dose of 300 IU in 6 dogs. Blood-flow was increased in all vascular beds, but insulin caused a redistribution of cardiac output. The greatest increases occurred in the femoral and carotid vascular beds, and the least occurred in the renal bed. Mesenteric blood-flow was increased in proportion to cardiac output. The results suggest that insulin exerts combined positive inotropic and vasodilating effects at high dose levels, which result in improved regional perfusion. It may be a potentially useful clinical agent with special benefit under circumstances where enhanced cerebral blood-flow is of importance.

Acute hemodynamic effects of a new inotropic agent, OPC-8212, on severe congestive heart failure

The hemodynamic and clinical effects of OPC-8212, a newly synthesized, orally effective inotropic agent, were assessed for the first time in ten patients with severe congestive heart failure by means of right heart catheterization with a Swan-Ganz catheter. Cardiac output was determined by the thermodilution technique. Patients received a single oral dose of 6 mg/kg. To determine the magnitude and time-course of the effects of OPC-8212, measurements were made during an observation period before and 2, 4, 8, and 12 h after administration. Blood was also taken at these times for measurement of the concentration of plasma OPC-8212. No large meals were allowed during the first 4 h. After the single oral dose of OPC-8212, plasma concentrations increased rapidly, reaching an effective level after 8 h and peaking at 12 h. Hemodynamic performance improved as the mean OPC-8212 plasma level increased, with the maximum effect being observed between 8 and 12 h after acute administration of the drug. At 8 h, the cardiac index was increased from the baseline value of 2.4 +/- 0.2 (SEM) to 2.8 +/- 0.3 1/min/m2 (P less than 0.01). The stroke work index rose from 26.2 +/- 5.1 to 31.7 +/- 60 g . m/m2. The excessive pulmonary artery diastolic pressure fell from 22 +/- 2 to 17 +/- 3 mmHg at 8 h (P less than 0.001) and to 16 +/- 2 mmHg (P less than 0.001) at 12 h. The incidence of ventricular premature beats was not increased and no other side effects were observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative immediate hemodynamic and hormonal effects of amrinone and captopril in patients with severe chronic heart failure

To compare the responses to oral inotropic and vasodilator drugs, maximally effective doses of amrinone (300 mg over 3 hours) and captopril (25 mg orally) were administered to 21 patients with severe chronic heart failure, who had not received either agent previously. Despite similar decreases in systemic vascular resistance with both drugs, amrinone produced greater increases in cardiac index (+ 0.56 vs. + 0.41/min/m2, p less than 0.05) and smaller decreases in mean arterial pressure (-11.1 vs. -15.2 mm Hg, p less than 0.05) than did captopril; three patients became symptomatically hypotensive with captopril, but none did so after amrinone. These differences were due to a significant decrease in heart rate with captopril (-6.3 beats/min, p less than 0.01), whereas heart rate increased with amrinone (+ 4.3 beats/min, p less than 0.01); the increases in stroke volume index with both drugs were similar. Despite similar decreases in left ventricular filling pressures, the decrease in mean right atrial pressure with amrinone was greater than with captopril (-5.6 vs. -3.2 mm Hg, p less than 0.01). This difference was the result of the greater decrease in pulmonary arteriolar resistance, and hence in right ventricular afterload, with amrinone than with captopril, (-33% vs. -16%, respectively), p less than 0.01. Despite these superior hemodynamic responses to amrinone, when patients received sequential long-term treatment with both drugs during the follow-up period, only 12% of patients benefitted during therapy with amrinone, whereas 64% improved clinically with captopril.(ABSTRACT TRUNCATED AT 250 WORDS)

Haemodynamic effects of low and high doses of insulin during beta receptor blockade in dogs

Haemodynamic effects of small and high doses of insulin during beta receptor blockade were studied in nine dogs. Beta receptor blockade was induced by 0.5 mg/kg propranolol and caused depression of cardiac performance with a significant increase in left ventricular end-diastolic pressure (LVEDP) and a significant decrease in heart rate; maximum rate of left ventricular (LV) pressure rise (LVdP/dtmax), stroke volume and cardiac output. At 15 min, after beta receptor blockade, a bolus injection of 0.5 IU/kg of insulin, free of glucagon and calcium, was given followed by a continuous infusion of 0.5 IU/kg/h. After 30 min another bolus dose of 300 IU insulin was injected. Glucose and potassium were given to maintain physiological levels of these factors. Five minutes after a low dose of insulin there was a significant decrease in LVEDP (P less than 0.01), and a significant increase in LVdP/dtmax (P less than 0.01), in stroke volume (P less than 0.01) and in cardiac output (P less than 0.01). The other haemodynamic variables were not significantly changed. Administration of a high dose of insulin further, significantly, improved performance of the beta receptor blocked heart and caused a significant reduction in total peripheral resistance. In conclusion, insulin exerts inotropic and vasodilator effects which are dose-dependent and not related to adrenergic mechanisms.

Positive inotropic and vasodilator actions of milrinone in patients with severe congestive heart failure. Dose-response relationships and comparison to nitroprusside

Milrinone is a potent positive inotropic and vascular smooth muscle-relaxing agent in vitro, and therefore, it is not known to what extent each of these actions contributes to the drug's hemodynamic effects in patients with heart failure. In 11 patients with New York Heart Association class III or IV congestive heart failure, incremental intravenous doses of milrinone were administered to determine the dose-response relationships for heart rate, systemic vascular resistance, and inotropic state, the latter measured by peak positive left ventricular derivative of pressure with respect to time (dP/dt). To clarify further the role of a positive inotropic action, the relative effects of milrinone and nitroprusside on left ventricular stroke work and dP/dt were compared in each patient at doses matched to cause equivalent reductions in mean arterial pressure or systemic vascular resistance, indices of left ventricular afterload. Milrinone caused heart rate, stroke volume, and dP/dt to increase, and systemic vascular resistance to decrease in a concentration-related manner. At the two lowest milrinone doses resulting in serum concentrations of 63 +/- 4 and 156 +/- 5 ng/ml, respectively, milrinone caused significant increases in stroke volume and dP/dt, but no changes in systemic vascular resistance or heart rate. At the maximum milrinone dose administered (mean serum concentration, 427 +/- 11 ng/ml), heart rate increased from 92 +/- 4 to 99 +/- 4 bpm (P less than 0.01), mean aortic pressure fell from 82 +/- 3 to 71 +/- 3 mmHg (P less than 0.01), right atrial pressure fell from 15 +/- 2 to 7 +/- 1 mmHg (P less than 0.005), left ventricular end-diastolic pressure fell from 26 +/- 3 to 18 +/- 3 (P less than 0.005), stroke volume index increased from 20 +/- 2 to 30 +/- 2 ml/m2 (P less than 0.005), stroke work index increased from 14 +/- 2 to 21 +/- 2 g X m/m2 (P less than 0.01), and dP/dt increased from 858 +/- 54 to 1,130 +/- 108 mmHg/s (P less than 0.005). When compared with nitroprusside for a matched reduction in mean aortic pressure or systemic vascular resistance, milrinone caused a significantly greater increase in stroke work index at the same or lower left ventricular end-diastolic pressure. Milrinone caused a concentration-related increase in dP/dt (32% increase at maximum milrinone dose), whereas nitroprusside had no effect. These data in patients with severe heart failure indicate that in addition to a vasodilating effect, milrinone exerts a concentration-related positive inotropic action that contributes significantly to the drug's overall hemodynamic effects. The positive inotropic action occurs at drug levels that do not exert significant chronotropic or vasodilator effects.

Comparative hemodynamic effects of intravenous dobutamine and MDL-17,043, a new cardioactive drug, in severe congestive heart failure

In 14 patients with severe congestive heart failure (CHF) due to ischemic heart disease or idiopathic dilated cardiomyopathy, the hemodynamic response to intravenous infusion of dobutamine (D) was compared to that of a new non-catechol, non-glycoside, inotropic and vasodilator agent, MDL-17,043 (MDL) administered in incremental intravenous doses. D and MDL produced comparable increases in cardiac index (L/min/m2) (1.8 +/- 0.4 to 2.9 +/- 0.8 and 1.7 +/- 0.3 to 3.3 +/- 0.6, respectively; both p = 0.001) and stroke volume index (ml/beat/m2) (24 +/- 8 to 35 +/- 9 and 22 +/- 7 to 39 +/- 11, respectively; both p = 0.001). Both D and MDL reduced left ventricular filling pressure (29 +/- 5 to 24 +/- 5 and 29 +/- 6 to 17 +2- 6 mm Hg, respectively; both p less than 0.05), and mean right atrial pressure (11 +/- 4 to 8 +/- 4 and 13 +/- 5 to 6 +/- 4 mm Hg, respectively; both p = 0.001). The overall changes in heart rate and mean arterial pressure were small with both D and MDL. However, MDL in comparison to D resulted in a significantly lower left ventricular filling pressure (p = 0.001), mean pulmonary arterial pressure (p = 0.001), and mean arterial pressure (p less than 0.05). The salutary hemodynamic effects of MDL on cardiac index and left ventricular filling pressure were sustained for an average of 9.6 hours, whereas the effects of D dissipated within 30 minutes of stopping the infusion. No serious adverse effects were noted during acute administration with either drug. Therefore, intravenous MDL may be a useful substitute for D in the acute therapy of severe CHF.

A new method for clinical assessment of the negative inotropic action of anaesthetics--with special reference to isoflurane and its effect on myocardial oxygenation

A new method for maintaining the peripheral determinants of myocardial oxygen demand constant is described. Intravenously administered phenylephrine and nitroglycerin were used to control afterload and preload. Heart rate was kept constant with atrial pacing. The method was used to establish the in vivo negative inotropic effect of 1% end-tidal isoflurane in eight patients with ischaemic heart disease during positive pressure ventilation (IPPV). Stroke volume measured during steady-state isoflurane anaesthesia and IPPV with preload, afterload, and heart rate kept constant was 23% below awake control. The decrease in myocardial oxygen consumption was 22% and correlated well (r = 0.891) with the fall in left ventricular performance (stroke volume).

Hemodynamic effects of a new inotropic agent, piroximone (MDL 19205), in patients with chronic heart failure

The hemodynamic and neurohumoral effects of cummulative intravenous doses of piroximone (MDL 19205), a noncatecholamine, nonglycoside, imidazole derivative with positive inotropic and vasodilating properties, were studied in eight patients with severe congestive heart failure. A dose of 1.25 mg/kg in seven patients and 1.75 mg/kg in one patient increased cardiac index by 75% from 1.96 to 3.41 liters/min per m2 and decreased systemic vascular resistance (-41%), right atrial (-66%) and pulmonary wedge pressure (-35%) (all p less than 0.005). Mean arterial pressure was slightly reduced from 78 to 71 mm Hg (p less than 0.05) and forearm blood flow increased by 42%. Plasma norepinephrine decreased from 830 to 542 pg/ml (p less than 0.05) and plasma renin activity tended to increase. In four patients, dobutamine (15 micrograms/kg per min) produced a comparable increase in cardiac index (+100%), but less decrease in pulmonary wedge pressure (-21 versus -41%, p less than 0.05 versus piroximone) and, unlike piroximone, significantly increased heart rate (+22%, p less than 0.05 versus piroximone) and heart rate-blood pressure product (+30%, p less than 0.01 versus piroximone). In four other patients, a single intravenous dose of piroximone (1 mg/kg) resulted in a 35% increase in the first derivative of left ventricular pressure (dP/dt) from 796 to 1,068 mm Hg/s (p less than 0.01). Thus, piroximone is a potent inotropic agent with an acute hemodynamic profile that may be more favorable than that of dobutamine. Because the drug is orally absorbed, clinical trials of chronic efficacy are indicated.