Bolus intravenous nitroglycerin predominantly reduces afterload in patients with excessive arterial elastance

Enantiomer-Specific Cardiovascular Effects of the Ketone Body 3-Hydroxybutyrate

BACKGROUND

The ketone body 3-hydroxybutyrate (3-OHB) increases cardiac output (CO) by 35% to 40% in healthy people and people with heart failure. The mechanisms underlying the effects of 3-OHB on myocardial contractility and loading conditions as well as the cardiovascular effects of its enantiomeric forms, D-3-OHB and L-3-OHB, remain undetermined.

METHODS AND RESULTS

Three groups of 8 pigs each underwent a randomized, crossover study. The groups received 3-hour infusions of either D/L-3-OHB (racemic mixture), 100% L-3-OHB, 100% D-3-OHB, versus an isovolumic control. The animals were monitored with pulmonary artery catheter, left ventricle pressure-volume catheter, and arterial and coronary sinus blood samples. Myocardial biopsies were evaluated with high-resolution respirometry, coronary arteries with isometric myography, and myocardial kinetics with D-[11C]3-OHB and L-[11C]3-OHB positron emission tomography. All three 3-OHB infusions increased 3-OHB levels (P<0.001). D/L-3-OHB and L-3-OHB increased CO by 2.7 L/min (P<0.003). D-3-OHB increased CO nonsignificantly (P=0.2). Circulating 3-OHB levels correlated with CO for both enantiomers (P<0.001). The CO increase was mediated through arterial elastance (afterload) reduction, whereas contractility and preload were unchanged. Ex vivo, D- and L-3-OHB dilated coronary arteries equally. The mitochondrial respiratory capacity remained unaffected. The myocardial 3-OHB extraction increased only during the D- and D/L-3-OHB infusions. D-[11C]3-OHB showed rapid cardiac uptake and metabolism, whereas L-[11C]3-OHB demonstrated much slower pharmacokinetics.

CONCLUSIONS

3-OHB increased CO by reducing afterload. L-3-OHB exerted a stronger hemodynamic response than D-3-OHB due to higher circulating 3-OHB levels. There was a dissocitation between the myocardial metabolism and hemodynamic effects of the enantiomers, highlighting L-3-OHB as a potent cardiovascular agent with strong hemodynamic effects.

A new perspective on an old method: gated SPECT imaging for left ventricular contractile function assessment

The ejection fraction (LVEF) is a commonly used marker of left ventricular function. However, because it is strongly influenced by loading conditions, it can be inaccurate in representing cardiac contractility. We therefore evaluated a gated SPECT based tool to simultaneously assess preload, afterload, and contractility. Using gated SPECT-determined ventricular volumes and arterial tension measurements, we calculated ventricular and arterial elastance (Ev and Ea), as well as end-diastolic volumes, which are surrogates for contractility, afterload, and preload, respectively. We applied this protocol to 1462 consecutive patients and assessed the ventricular function in patients with and without myocardial infarction. The median LVEF was 68% (IQR 62-74%). Patients with infarction exhibited decreased contractility (ventricular elastance of 3 mmHg/ml vs. 6 mmHg/ml), compensated by an increase of preload (end-diastolic volume of 100 ml vs. 78 ml) and a decrease in afterload (arterial elastance of 1.8 mmHg/ml vs. 2.2 ml/mmHg). These interactions yielded a preserved ejection fraction in both groups. Gated SPECT-measured volumes were consistent with values reported in the literature. In addition, the combination of nuclear imaging and arterial tension measurement accounted for not only the ejection fraction but also the loading context, providing a more accurate representation of cardiac contractility.

Nicardipine: When high dose nitrates fail in treating heart failure

Sympathetic Crashing Acute Pulmonary Edema (SCAPE) describes patients who present with acute hypertensive cardiogenic pulmonary edema. These patients present in respiratory distress, and requiring immediate medical and airway management. The treatment of SCAPE includes non-invasive positive pressure ventilation (NIPPV) to maintain oxygenation, and high dose nitrates to lower blood pressure and reduce afterload. We present a case report of a patient with refractory hypertension to high dose nitrates likely due to nitroglycerin resistance or an attenuated response. The addition of nicardipine led to marked clinical improvement, normalized blood pressure and spared the patient from endotracheal intubation and admission to the intensive care unit.

Treatment of Hypertensive Cardiogenic Edema with Intravenous High-Dose Nitroglycerin in a Patient Presenting with Signs of Respiratory Failure: A Case Report and Review of the Literature

BACKGROUND Pulmonary edema is the accumulation of fluid in the lung secondary to increased hydrostatic pressure. Hypertensive cardiogenic pulmonary edema presents with a sudden onset of severe dyspnea, tachycardia, and tachypnea, and can occur when the systolic blood pressure exceeds 160 mmHg in association with acute decompensated congestive cardiac failure (CCF). A case is presented of hypertensive cardiogenic pulmonary edema treated with high-dose nitroglycerin and includes a review of the literature. CASE REPORT A 63-year-old Hispanic male with a medical history of hypertension, coronary artery disease, heart failure with a reduced ejection fraction of 35%, chronic kidney disease (CKD) and diabetes mellitus, presented as an emergency with acute, severe dyspnea. The patient was initially managed with 100% oxygen supplementation and intravenous (IV) high-dose nitroglycerin (30 mcg/min), which was titrated every 3 minutes, increasing by 15 mcg/min until a dose of 120 mcg/min was reached. After 18 minutes of aggressive therapy, the patient's condition improved and he no longer required mechanical ventilation. CONCLUSIONS Hypertensive cardiogenic pulmonary edema is a challenging clinical condition that should be diagnosed and managed as early as possible, and distinguished from respiratory failure due to other causes. Although hypertensive cardiogenic pulmonary edema is usually managed acutely with high-dose diuretics, this case has highlighted the benefit of high-dose IV nitroglycerin, and review of the literature supports this treatment approach.

Effect of nitric oxide on spinal evoked potentials and survival rate in rats with decompression sickness

Nitric oxide (NO) releasing agents have, in experimental settings, been shown to decrease intravascular nitrogen bubble formation and to increase the survival rate during decompression sickness (DCS) from diving. The effect has been ascribed to a possible removal of preexisting micronuclei or an increased nitrogen washout on decompression through augmented blood flow rate. The present experiments were conducted to investigate whether a short- or long-acting NO donor [glycerol trinitrate (GTN) or isosorbide-5-mononitrate (ISMN), respectively] would offer the same protection against spinal cord DCS evaluated by means of spinal evoked potentials (SEPs). Anesthetized rats were decompressed from a 1-h hyperbaric air dive at 506.6 kPa (40 m of seawater) for 3 min and 17 s, and spinal cord conduction was studied by measurements of SEPs. Histological samples of the spinal cord were analyzed for lesions of DCS. In total, 58 rats were divided into 6 different treatment groups. The first three received either saline (group 1), 300 mg/kg iv ISMN (group 2), or 10 mg/kg ip GTN (group 3) before compression. The last three received either 300 mg/kg iv ISMN (group 4), 1 mg/kg iv GTN (group 5), or 75 μg/kg iv GTN (group 6) during the dive, before decompression. In all groups, decompression caused considerable intravascular bubble formation. The ISMN groups showed no difference compared with the control group, whereas the GTN groups showed a tendency toward faster SEP disappearance and shorter survival times. In conclusion, neither a short- nor long-acting NO donor had any protective effect against fatal DCS by intravenous bubble formation. This effect is most likely due to a fast ascent rate overriding the protective effects of NO, rather than the total inert tissue gas load.

Clevidipine in acute heart failure: Results of the A Study of Blood Pressure Control in Acute Heart Failure-A Pilot Study (PRONTO)

BACKGROUND

Rapid blood pressure (BP) control improves dyspnea in hypertensive acute heart failure (AHF). Although effective antihypertensives, calcium-channel blockers are poorly studied in AHF. Clevidipine is a rapidly acting, arterial selective intravenous calcium-channel blocker. Our purpose was to determine the efficacy and safety of clevidipine vs standard-of-care intravenous antihypertensive therapy (SOC) in hypertensive AHF.

METHODS

This is a randomized, open-label, active control study of clevidipine vs SOC in emergency department patients with AHF having systolic BP ≥160 mm Hg and dyspnea ≥50 on a 100-mm visual analog scale (VAS). Coprimary end points were median time to, and percent attaining, a systolic BP within a prespecified target BP range (TBPR) at 30 minutes. Dyspnea reduction was the main secondary end point.

RESULTS

Of 104 patients (mean [SD] age 61 [14.9] years, 52% female, 80% African American), 51 received clevidipine and 53 received SOC. Baseline mean (SD) systolic BP and VAS dyspnea were 186.5 (23.4) mm Hg and 64.8 (19.6) mm. More clevidipine patients (71%) reached TBPR than did those receiving SOC (37%; P = .002), and clevidipine was faster to TBPR (P = .0006). At 45 minutes, clevidipine patients had greater mean (SD) VAS dyspnea improvement than did SOC patients (-37 [20.9] vs -28 mm [21.7], P = .02), a difference that remained significant up to 3 hours. Serious adverse events (24% vs 19%) and 30-day mortality (3 vs 2) were similar between clevedipine and SOC, respectively, and there were no deaths during study drug administration.

CONCLUSIONS

In hypertensive AHF, clevidipine safely and rapidly reduces BP and improves dyspnea more effectively than SOC.

Vasodilators in Acute Heart Failure: Review of the Latest Studies

Vasodilators play an important role in the management of acute heart failure, particularly when increased afterload is the precipitating cause of decompensation. The time-honored approach to afterload reduction has been largely focused on use of intravenous nitrovasodilators and, when properly dosed, this class of agents does provide substantial symptom relief for patients with acute hypertensive heart failure. Despite this, nitrovasodilators have never been shown to diminish mortality or provide any post-discharge outcome benefit leading to an on-going search for viable and more effective alternatives. While no new vasodilators have been approved for use in acute heart failure since nesiritide more than a decade ago, a number of novel agents have been developed, with some showing significant promise in recent clinical trials. In this review, we summarize the latest study data as it relates to vasodilator therapy and provide a glimpse into the not too distant future state of acute heart failure care.

Longitudinal changes in left ventricular stiffness: a community-based study

BACKGROUND

Cross-sectional studies suggest that left ventricular (LV) and arterial elastance (stiffness) increase with age, but data examining longitudinal changes within human subjects are lacking. In addition, it remains unknown whether age-related LV stiffening is merely a reaction to arterial stiffening or caused by other processes.

METHODS AND RESULTS

Comprehensive echo-Doppler cardiography was performed in 1402 subjects participating in a randomly selected community-based study at 2 examinations separated by 4 years. From this population, 788 subjects had adequate paired data to determine LV end-systolic elastance (Ees), end-diastolic elastance (Eed), and effective arterial elastance. Throughout 4 years, blood pressure, arterial elastance, and LV mass decreased, coupled with significantly greater use of antihypertensive medications. However, despite reductions in arterial load, Ees increased by 14% (2.10±0.67-2.26±0.70 mm Hg/mL; P<0.0001) and Eed increased by 8% (0.13±0.03-0.14±0.04 mm Hg/mL; P<0.0001). Increases in Eed were greater in women than men, whereas Ees changes were similar. Age-related increases in Ees and Eed were correlated with changes in body weight, but were similar in subjects with or without cardiovascular disease. Changes in Ees were correlated with Eed (r=0.5; P<0.0001), but not with other measures of contractility, indicating that the increase in Ees was reflective of passive stiffening rather than enhanced systolic function.

CONCLUSIONS

Despite reductions in arterial load with medical therapy, LV systolic and diastolic stiffness increase over time in humans, particularly in women. In addition to blood pressure control, therapies targeting load-independent ventricular stiffening may be effective to treat and prevent age-associated cardiovascular diseases, such as heart failure.

Acute Heart Failure Treatment

Dyspnea is the predominant symptom for patients with acute heart failure and initial treatment is largely directed towards the alleviation of this. Contrary to conventional belief, not all patients present with fluid overload and the approach to management is rapidly evolving from a solitary focus on diuresis to one that more accurately reflects the complex interplay of underlying cardiac dysfunction and acute precipitant. Effective treatment thus requires an understanding of divergent patient profiles and an appreciation of various therapeutic options for targeted patient stabilization. The key principle within this paradigm is directed management that aims to diminish the work of breathing through situation appropriate ventillatory support, volume reduction and hemodynamic improvement. With such an approach, clinicians can more efficiently address respiratory discomfort while reducing the likelihood of avoidable harm.

Hemodynamic characteristics of patients with diastolic heart failure and hypertension

Diastolic heart failure (DHF) has different underlying pathophysiologic mechanisms. We sought to compare hemodynamic characteristics in DHF patients with or without hypertension. A conductance catheter with microtip-manometer was used to measure left ventricular (LV) function and hemodynamics in 28 DHF patients. After baseline measurements, nitroglycerin was infused to alter the loading condition and the measurements were repeated. At baseline, end-systolic pressure was higher and the time constant of LV relaxation (tau) was longer in hypertensive DHF patients. Patients in hypertensive DHF had lower LV-arterial coupling ratio than those in non-hypertensive DHF. The peak of loading sequence was in early systole in non-hypertensive DHF patients and in late systole in hypertensive DHF patients. Nitroglycerin decreased LV end-systolic pressure and end-diastolic volume in both groups. In non-hypertensive DHF, nitroglycerin significantly reduced stroke volume and shortened tau (59+/-11 vs. 54+/-10 ms, p<0.05) without any changes in the time to peak LV force, effective arterial elastance (E(a)), or LV-arterial coupling ratio. In contrast, in hypertensive DHF patients, nitroglycerin significantly reduced E(a) and shortened the time to peak LV force, resulting in an improved LV-arterial coupling ratio, preserved stroke volume and shortened tau (75+/-14 vs. 62+/-13 ms, p<0.05). In conclusion, LV relaxation was more prolonged in hypertensive DHF patients than non-hypertensive DHF patients, partly because of the different loading sequence. Changing the loading condition by nitroglycerin improved LV systolic and diastolic function in hypertensive DHF patients.

Treatment of Severe Decompensated Heart Failure With High-Dose Intravenous Nitroglycerin: A Feasibility and Outcome Analysis

STUDY OBJECTIVE

We perform a feasibility and outcome assessment of the treatment of severe decompensated heart failure with high-dose nitroglycerin.

METHODS

This study was designed as a nonrandomized, open-label, single-arm study of high-dose nitroglycerin. Patients with hypertension (systolic blood pressure > or = 160 mm Hg or mean arterial pressure > or = 120 mm Hg) who were refractory to initial therapy were eligible for inclusion. Enrolled patients began receiving a titratable nitroglycerin infusion and were given a bolus of high-dose nitroglycerin (2 mg). Repeated administration of high-dose nitroglycerin was allowed every 3 minutes, up to a total of 10 doses. Predefined effectiveness and safety outcomes were tracked throughout hospital admission. To provide a frame of reference for these outcomes, data were retrospectively compiled for similar patients with severe decompensated heart failure who did not receive high-dose nitroglycerin.

RESULTS

Twenty-nine patients received high-dose nitroglycerin. Endotracheal intubation was required in 13.8% of patients, bilevel positive airway pressure (BiPAP) ventilation in 6.9%, and ICU admission in 37.9%. Symptomatic hypotension developed in 1 patient (3.4%), and biomarker evidence of myocardial infarction was found in 17.2% of patients. The mean dose of high-dose nitroglycerin was 6.5 mg (+/-3.4). For patients who were treated without high-dose nitroglycerin (n=45), endotracheal intubation occurred in 26.7%, BiPAP in 20.0%, and ICU admission in 80.0%. None of these patients developed symptomatic hypotension, and biomarker evidence of myocardial infarction was observed in 28.9% of patients.

CONCLUSION

In this nonrandomized, open-label trial, high-dose nitroglycerin was associated with endotracheal intubation, BiPAP, and ICU admission less frequently than expected to occur without high-dose nitroglycerin, and adverse events were uncommon. Treatment of hypertensive, severely decompensated heart failure patients with high-dose nitroglycerin seems promising, but a randomized, blinded study is needed to more completely define its clinical utility. According to this trial, such a study seems feasible.

Ventriculovascular coupling in systolic and diastolic heart failure

Pressure-volume analysis has provided critical insight into ventricular mechanics, and it has elucidated the underlying mechanisms of heart failure (HF). Renewed interest in ventriculovascular coupling, the interaction of the left ventricle and the arterial system, has developed from recent investigations focusing on the importance of heart rate control in systolic HF, blood pressure lability in the elderly, and acute pulmonary edema in patients with HF and a normal ejection fraction. These data suggest that abnormal ventriculovascular coupling may be an additional pathophysiologic mechanism underlying the development of HF with a normal ejection fraction and may provide a target for novel therapies.

Elucidating the relationship between cardiac preload and renal perfusion under pneumoperitoneum

INTRODUCTION

Pneumoperitoneum is associated with a well-described decrease in renal blood flow, but it remains unclear whether a decrease in cardiac preload is responsible. Our aim was to characterize the relationship between cardiac preload and renal perfusion during pneumoperitoneum.

METHODS

Eleven pigs were submitted to three 30 minute study periods: 1) Baseline (n=11): no interventions, 2) Pneumoperitoneum (n=11): 12 mmHg CO2 pneumoperitoneum, 3) Preload Reduction: pneumoperitoneum and nitroglycerin infusion (n=8); or pneumoperitoneum and hemorrhage to a mean arterial pressure (MAP) of 40 mmHg (n=3). Echocardiographic measurements of left ventricular end-diastolic diameter (LVEDD) were used as an index of preload. Renal cortical perfusion (RCP) was measured using laser doppler flowmetry.

RESULTS

LVEDD decreased from 4.2 +/- 0.5 to 4.1 +/- 0.6 cm (p=0.02) with pneumoperitoneum and then to 4.0 +/- 0.5 cm (p=0.03) with the addition of nitroglycerin. There was no statistically significant change in RCP with pneumoperitoneum (33.5 +/- 8.4 to 28.5 +/- 8.4 ml/min/100g tissue, p=0.2), but it decreased to 18.5 +/- 11.3 ml/min/100g tissue (p=0.001) with the addition of nitroglycerin. The correlation between RCP and LVEDD was weak (0.35, p=0.003), whereas correlation between RCP and MAP was superior (R=0.59, p<0.0001).

CONCLUSIONS

While decreasing preload under extreme lab conditions also decreases RCP, simply creating a pneumoperitoneum of 12 mmHg does not. The decrease in renal blood flow associated with pneumoperitoneum is likely not solely a function of preload.

Ventriculovascular coupling in systolic and diastolic heart failure

Pressure-volume analysis has provided critical insight into ventricular mechanics, and it has elucidated the underlying mechanisms of heart failure (HF). Renewed interest in ventriculovascular coupling, the interaction of the left ventricle and the arterial system, has developed from recent investigations focusing on the importance of heart rate control in systolic HF, blood pressure lability in the elderly, and acute pulmonary edema in patients with HF and a normal ejection fraction. These data suggest that abnormal ventriculovascular coupling may be an additional pathophysiological mechanism underlying the development of HF with a normal ejection fraction and may provide a target for novel therapies.

Modern Management of Cardiogenic Pulmonary Edema

Cardiogenic pulmonary edema (CPE) is a life-threatening condition that is frequently encountered in standard emergency medicine practice. Traditionally, diagnosis was based on physical assessment and chest radiography and treatment focused on the use of morphine sulfate and diuretics. Numerous advances in diagnosis and treatment have been made, however. Serum testing for B-type natriuretic peptide (BNP) has improved the accuracy of diagnoses in these patients. Treatment should focus on fluid redistribution with aggressive preload and afterload reduction rather than simply on diuresis. Some specific medications and noninvasive positive pressure ventilation have been shown to be safe and rapidly effective in improving patients' symptoms and improve outcomes.

Nitroglycerin improves left ventricular relaxation by changing systolic loading sequence in patients with excessive arterial load

Nitroglycerin abbreviates left ventricular (LV) relaxation through improved hemodynamics as well as by direct actions on the myocardium. The aim of this study was to examine whether the changing systolic loading sequence during nitroglycerin administration affects LV relaxation in patients with excessive arterial load. By use of a conductance catheter with microtip manometer, the effects of intravenous nitroglycerin (0.3-0.5 microg/kg/min) on LV function and hemodynamics were examined in 39 patients with various degrees of LV contractility. Patients were divided into two groups according to LV-arterial coupling, the ratio of end-systolic elastance (Ees) to effective arterial elastance (Ea). In patients with Ees/Ea ratio > 1, nitroglycerin had no effect on the time to peak force or on the time constant of LV relaxation (tau). On the other hand, in patients with Ees/Ea < 1, which represented excessive arterial load, nitroglycerin significantly shortened the time to peak force, shifted the peak of the loading sequence from late to early systole, and significantly decreased tau without any changes in Ees. Thus, nitroglycerin improved LV relaxation in patients with excessive arterial load partly by changing the systolic loading sequence.

Assessment of arterial ventricular coupling changes in patients under therapy with various antihypertensive agents by a non-invasive echocardiographic method

BACKGROUND

The integration between arterial and ventricular function has been studied by mostly invasive techniques. We considered assessing the influence of various antihypertensive medications on arterial-ventricular coupling (AVC) with the use of a non-invasive echocardiographic method.

METHODS

A total of 9037 patients, who had been under treatment for essential arterial hypertension were studied echocardiographically at baseline prior to therapy and after 6 months of antihypertensive monotherapy (diuretics, beta-blockers without intrinsic sympathomimetic activity (ISA), beta-blockers with ISA, a-blockers, angiotensin converting enzyme inhibitors (ACEI), angiotensin II receptor blockers (AIIRA), non-dihydropyridine calcium antagonists, and dihydropyridine calcium antagonists). The AVC was calculated by echocardiographic measurements based on the equation: AVC=ESV/SV (ESV, end systolic volume; SV, stroke volume).

RESULTS

ACEI, AIIRA, and dihydropyridine calcium antagonists decreased (P<0.0001 for all) while diuretics, alpha-blockers, both beta-blocker groups, and non-dihydropyridines increased significantly the AVC values compared to baseline measurements (P<0.0001 for all, except P=0.02 for alpha-blockers). Changes in AVC were the most highly correlated with changes in EF (r=-0.979, P<0.0001).

CONCLUSION

Various antihypertensive drugs have a differential effect on AVC with ACEI, AIIRA, and dihydropyridine calcium antagonists having the most favorable effect on this index. AVC provides a meaningful index of cardiovascular performance in hypertension and offers the possibility of wide employment and serial follow-up in large numbers of patients because of its completely non-invasive nature.

Positive inotropic and lusitropic effects of HNO/NO- in failing hearts: independence from beta-adrenergic signaling

Nitroxyl anion (HNONO(-)), the one-electron reduced form of nitric oxide (NO), induces positive cardiac inotropy and selective venodilation in the normal in vivo circulation. Here we tested whether HNO/NO(-) augments systolic and diastolic function of failing hearts, and whether contrary to NO/nitrates such modulation enhances rather than blunts beta-adrenergic stimulation and is accompanied by increased plasma calcitonin gene-related peptide (CGRP). HNO/NO(-) generated by Angelis' salt (AS) was infused (10 microg/kg per min, i.v.) to conscious dogs with cardiac failure induced by chronic tachycardia pacing. AS nearly doubled contractility, enhanced relaxation, and lowered cardiac preload and afterload (all P < 0.001) without altering plasma cGMP. This contrasted to modest systolic depression induced by an NO donor diethylamine(DEA)NO or nitroglycerin (NTG). Cardiotropic changes from AS were similar in failing hearts as in controls despite depressed beta-adrenergic and calcium signaling in the former. Inotropic effects of AS were additive to dobutamine, whereas DEA/NO blunted beta-stimulation and NTG was neutral. Administration of propranolol to nonfailing hearts fully blocked isoproterenol stimulation but had minimal effect on AS inotropy and enhanced lusitropy. Arterial plasma CGRP rose 3-fold with AS but was unaltered by DEA/NO or NTG, supporting a proposed role of this peptide to HNO/NO(-) cardiotropic action. Thus, HNO/NO(-) has positive inotropic and lusitropic action, which unlike NO/nitrates is independent and additive to beta-adrenergic stimulation and stimulates CGRP release. This suggests potential of HNO/NO(-) donors for the treatment of heart failure.

Evaluation and management of acutely decompensated chronic heart failure in the emergency department

A wide range of patients with symptomatic heart failure seek treatment in the emergency department. While there is no single approach to the diversity of patients with acutely decompensated heart failure, certain overarching principles apply. For patients with acute pulmonary edema or cardiogenic shock, the first priority must be rapid stabilization and treatment of reversible problems. For patients with less dramatic presentations, a more systematic search for precipitating factors may be required. Therapy, in general, is directed at reversing dyspnea and/or hypoxemia caused by pulmonary edema, improving systemic perfusion, and reducing myocardial oxygen demand. While morphine and diuretics still have their traditional roles, vasodilators and inotropic agents play an increasingly important part in the modern pharmacologic approach to decompensated heart failure in the emergency department. After evaluation and stabilization in the emergency department, most patients will require hospital admission, although a subset of low-risk patients may be appropriate for discharge to home following a period of observation. Strategies to optimize emergency department care are likely to have an impact upon patient outcomes and upon resource utilization. (c)2001 by CHF, Inc.

Assessment of diastolic dysfunction. Invasive modalities

In this article, the author sought to review the two primary components of diastolic function that are most directly and accurately determined using invasive methodologies. For chamber relaxation this is optimally achieved using a micromanometer catheter, whereas for chamber compliance (or its inverse stiffness) this is best achieved by combining this catheter with a measure of instantaneous volume from a conductance catheter, using data from multiple cycles. Even with the ideal data set, the analysis of both properties involves physiologic and often mathematical assumptions, and the extent to which the data do not match these assumptions, the derived indexes may be misleading. Care in the data collection, and awareness of the various factors and pitfalls involved with their analysis can undoubtedly improve the interpretations. As advances in noninvasive methods continue to evolve, reliance on invasive methodologies will continue to fade into the background. At present, however, they remain the gold standard for the two primary diastolic properties described, and have clearly played a central role in the evolution of our understanding of cardiac diastolic disease and its treatment.

Means for load variation during echocardiographic assessment of the Frank-Starling relationship

Because minimally invasive methods of preload variation are not validated for load-insensitive indexes of cardiac performance, intravenous nitroglycerin (NTG), phenylephrine, and saline solution (VOL) boluses were used in blocked and intact autonomic states to alter load and were compared with vena caval occlusion in the assessment of preload recruitable stroke work relationships between stroke work and left ventricular end-diastolic volume in dogs. In both autonomic states NTG and VOL produced comparable linear relationships. NTG and saline solution were combined with noninvasive measurements of left ventricular pressure and volume to construct echocardiographic relationships between stroke work and left ventricular end-diastolic cross-sectional area; NTG produced linear relationships similar to vena caval occlusion. Therefore NTG and VOL reliably alter load in constructing preload recruitable stroke work relationships, and NTG may be used with noninvasive measurements to provide load-insensitive estimates of cardiac function in a minimally invasive manner.

Impact of vascular adaptation to chronic aortic regurgitation on left ventricular performance

BACKGROUND

This investigation was designed to test the hypothesis that vascular adaptation occurs in patients with chronic aortic regurgitation to maintain left ventricular (LV) performance.

METHODS AND RESULTS

Forty-five patients with chronic aortic regurgitation (mean age 50+/-14 years) were studied using a micromanometer LV catheter to obtain LV pressures and radionuclide ventriculography to obtain LV volumes during multiple loading conditions and right atrial pacing. These 45 patients were subgrouped according to their LV contractility (Ees) and ejection fraction values. Group I consisted of 24 patients with a normal Ees. Group IIa consisted of 10 patients with impaired Ees values (Ees <1.00 mm Hg/mL) but normal LV ejection fractions; Group IIb consisted of 11 patients with impaired contractility and reduced LV ejection fractions. The left ventricular-arterial coupling ratio, Ees/Ea, where Ea was calculated by dividing the LV end-systolic pressure by LV stroke volume, averaged 1.60+/-0.91 in Group I. It decreased to 0.91+/-0.27 in Group IIa (P<0.05 versus Group I), and it decreased further in Group IIb to 0.43+/-0.24 (P<0.001 versus Groups I and IIa). The LV ejection fractions were inversely related to the Ea values in both the normal and impaired contractility groups (r=-0.48, P<0.05 and r=-0.56, P<0.01, respectively), although the slopes of these relationships differed (P<0.05). The average LV work was maximal in Group IIa when the left ventricular-arterial coupling ratio was near 1.0 because of a significant decrease in total arterial elastance (P<0.01 versus Group I). In contrast, the decrease in the left ventricular-arterial coupling ratio in Group IIb was caused by an increase in total arterial elastance, effectively double loading the LV, contributing to a decrease in LV pump efficiency (P<0.01 versus Group IIa and P<0.001 versus Group I).

CONCLUSIONS

Vascular adaptation may be heterogeneous in patients with chronic aortic regurgitation. In some, total arterial elastance decreases to maximize LV work and maintain LV performance, whereas in others, it increases, thereby double loading the LV, contributing to afterload excess and a deterioration in LV performance that is most prominent in those with impaired contractility.

Isosorbide aerosol: an option for the treatment of hypertensive crises

In this study the authors assessed the effectiveness and safety of isosorbide dinitrate aerosol administered through the oral mucosa in 30 adult patients who presented with a hypertensive crisis (mean arterial pressure > 130 mm Hg and evidence of target organ damage). The patients were given a first dose of 1.25 mg of aerosol when they were admitted to the hospital; a second dose was administered 15 minutes later if the mean arterial pressure had not decreased by > 15%. An electrocardiogram (ECG) was obtained for every patient immediately prior to and 30 minutes after administration of the medication. Nine patients (30%) had a good response with one dose, whereas 21 patients (70%) required a second dose. All 30 patients had a significant reduction of the arterial blood pressure (187+/-13 / 121+/-6.6 to 153+/-15.3 / 92.3+/-7.6 mm Hg; p<0.005) as well as of the mean arterial pressure (136.6+/-8 to 109.5+/-7 mm Hg; p<0.005) in a period of 30 minutes. No adverse effects, rebound hypertension, or severe hypotension were observed. These figures remained under control for 6 hours. Two of the patients had angina pectoris at admission and their ECG showed subepicardial ischemia, both of which disappeared with the medication. A second ECG appeared normal. A reduction of 14% in heart rate was obtained (95+/-15 to 82+/-14 beats per minute; p<0.005). These observations suggest that isosorbide dinitrate aerosol is an effective and safe alternative for the treatment of patients with hypertensive crises.

Effects of mental stress on left ventricular and peripheral vascular performance in patients with coronary artery disease

OBJECTIVES

We sought to investigate the mechanism of a mental stress-induced fall in left ventricular ejection fraction (LVEF) in patients with coronary artery disease.

BACKGROUND

Mental stress induces a fall in LVEF in a significant proportion of patients with coronary artery disease. This is accompanied by an increase in heart rate, blood pressure and rate-pressure product. Whether the mental stress-induced fall in LVEF is due to myocardial ischemia, altered loading conditions or a combination of both is not clear.

METHODS

Left ventricular (LV) function was studied noninvasively by serial equilibrium radionuclide angiocardiography and simultaneous measurement of peak power, a relatively afterload-independent index of LV contractility, in 21 patients with coronary artery disease (17 men, 4 women) and 9 normal subjects (6 men, 3 women) at baseline, during mental stress and during exercise. Peripheral vascular resistance (PVR), cardiac output (CO), arterial and end-systolic ventricular elastance (Ea, Ees,) and ventriculoarterial coupling (V/AC) were also calculated. Patients underwent two types of mental stress-mental arithmetic and anger recall-as well as symptom-limited semisupine bicycle exercise.

RESULTS

Nine patients (43%) had an absolute fall in LVEF of > or = 5% (Group I) in response to at least one of the mental stressors, whereas the remaining patients did not (Group II). Group I and Group II patients were similar in terms of baseline characteristics. Both groups showed a significant but comparable increase in systolic blood pressure (15+/-7 vs. 9+/-10 mm Hg, p=0.12) and a slight increase in heart rate (7+/-4 vs. 8+/-7 beats/min, p=0.6) and a comparable increase in rate-pressure product (2.2+/-0.9 vs. 1.9+/-1.2 beats/min x mm Hg, p=0.6) with mental stress. However, PVR increased in Group I and decreased in Group II (252+/-205 vs. -42+/-230 dynes x s x cm(-5), p=0.006), and CO decreased in Group I and increased in Group II (-0.2+/-0.4 vs. 0.6+/-0.7 liters/min, p=0.02) with mental stress. There was no difference in the change in peak power (p=0.4) with mental stress. With exercise, an increase in systolic blood pressure, heart rate, rate-pressure product and CO and a fall in PVR were similar in both groups. Of the two mental stressors, anger recall resulted in a greater fall in LVEF and a greater increase in diastolic blood pressure. Exercise resulted in a fall in LVEF in 7 patients (33%). However, exercise-induced changes in LVEF and hemodynamic variables were not predictive of mental stress-induced changes in LVEF and hemodynamic variables. Conclusions. Abnormal PVR and Ea responses to mental stress and exercise are observed in patients with a mental stress-induced fall in LVEF. Peripheral vasoconstrictive responses to mental stress contribute significantly toward a mental stress-induced fall in LVEF.

Acute hemodynamic effects of metoprolol +/- nitroglycerin in patients with biopsy-proven lymphocytic myocarditis

We evaluated acute hemodynamic effects of metoprolol +/- nitroglycerin in 11 patients with left ventricular dysfunction and biopsy-proven lymphocytic myocarditis. Acute administration of metoprolol improved ejection phase indexes, probably through the prolongation of diastole; the addition of a vasodilator further enhanced these effects by improving arterial elastance.

Management of patients with chronic stable angina at low risk for serious cardiac events

Successful management of the patient with chronic stable angina requires correct stratification by assessing the risk of future coronary events. Patients at low risk for such events have a relatively good prognosis; revascularization procedures (balloon angioplasty or surgery) offer no benefit over medical management. Such patients should be offered medical therapy as their first option. The goals in management of chronic stable angina are (1) treatment of other conditions that may worsen angina; (2) treatment with aspirin and modification of risk factors for coronary artery disease (CAD) to improve outcome; and (3) effective relief of anginal symptoms. Most patients with stable angina will have CAD. It is well established that treatment with aspirin and modification of risk factors for CAD are beneficial in reducing cardiovascular mortality and morbidity. Blood pressure reduction, lowering of blood cholesterol level, and smoking cessation are interventions of proven value and appear to correct defects (at least partially) in the endothelial function of the coronary blood vessels. Other interventions that are helpful are estrogen replacement treatment in postmenopausal women, and low-dose aspirin therapy-which is recommended for all patients who can tolerate it. For controlling symptoms and improving angina-free walking time, nitrates, beta blockers, and calcium channel antagonists are efficacious as first-line monotherapy for chronic stable angina in this group of patients. Nitrates may be of special use in patients with impaired left ventricular function, overt congestive heart failure, intermittent coronary vasoconstriction, or coronary artery spasm. In patients with concomitant hypertension or supraventricular tachycardia, beta blockers are helpful. Calcium channel antagonists may be useful in patients with chronic obstructive pulmonary disease, peripheral vascular disease, or hypertension. When optimal monotherapy with a given class of drug fails to control symptoms, alternative monotherapy with a different class of agent should be tried before combination therapy. Combination therapy with 2 or 3 agents is not always superior to optimal monotherapy. Patients who fail to respond to adequate medical therapy should be considered for a revascularization procedure.

Beneficial actions of nitrates in cardiovascular disease

Nitroglycerin and the long-acting nitrates have been used in cardiovascular medicine for >100 years. Nitrates are widely utilized for the various anginal syndromes and are also used in congestive heart failure and patients with left ventricular dysfunction. The potential mechanisms for relief of myocardial ischemia with nitrates are multiple. The nitrovasodilators are a related group of drugs that result in the formation of nitric oxide (NO) within vascular smooth muscle cells. NO stimulates the enzyme guanylate cyclase, which results in increases in cyclic guanosine monophosphate and vasodilation. In the presence of atherosclerosis, endothelial dysfunction is ubiquitous and associated with decreased NO availability, probably due to increased destruction of NO by free radical anions. Nitrovasodilators, including the nitrates, supply exogenous NO to the vascular wall and improve the vasodilator state. When nitrates are administered, endothelial-dependent stimuli cause relaxation rather than constriction in the setting of endothelial dysfunction. Nitrates also have antiplatelet effects, and recent evidence confirms that these drugs decrease platelet aggregation and thrombosis formation. This may play an important role in the therapy of acute unstable myocardial ischemia, including unstable angina and myocardial infarction. Nitrate hemodynamic effects have been long known. They are primarily modulated through a decrease in myocardial work that results from smaller cardiac chambers operating with lower systolic and diastolic pressures. These changes are caused by a redistribution of the circulating blood volume away from the heart to the venous capacitance system, with a fall in venous return to the heart. The afterload or arterial effects of nitrates are also useful in decreasing myocardial oxygen consumption. Considerable evidence confirms a variety of mechanisms whereby nitrates increase coronary blood flow, including epicardial coronary artery dilation, stenosis enlargement, enhanced collateral size and flow, improvement of endothelial dysfunction, and prevention or reversal of coronary artery vasoconstriction. These effects help increase nutrient coronary blood flow to zones of myocardial ischemia. Recent data with the nitroglycerin patch confirm that myocardial ischemia is decreased after nitrate administration. Nitroprusside, another nitrovasodilator, is a commonly used intravenous agent for lowering arterial pressure and left ventricular filling pressure. This drug is highly effective for the treatment of acute or severe hypertension and congestive heart failure. However, there are data suggesting that nitroprusside may be deleterious in the presence of acute myocardial ischemia, perhaps by shunting blood away from zones of jeopardized myocardial blood flow. Therefore, nitroprusside cannot be recommended to treat myocardial ischemia; intravenous nitroglycerin should be used in this context.