Combined hemodynamic effects of dobutamine and IV nitroglycerin in congestive heart failure

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.

Congestive heart failure and pulmonary edema for the emergency physician

Congestive heart failure (CHF) and pulmonary edema are major health problems in the United States as well as across the rest of the developing world. The prevalence of CHF and pulmonary edema in the general population results in a significant number of these patients presenting to Emergency Departments (EDs). Mortality from these disorders is substantial, with a 5-year mortality rate for patients requiring hospitalization of approximately 50%. Understanding of the clinical syndromes of CHF and pulmonary edema requires review of the basic determinants of cardiovascular performance. Preload, afterload, contractility, and heart rate may all be modified by pharmacological or mechanical techniques. Diuretics, vasodilators, cardiac glycosides, and other inotropes all may play a role in the ED management of CHF. In rare instances, mechanical devices for support of the heart and circulation may be indicated.

Nitrates in congestive heart failure

Nitrates are commonly used in the therapy of congestive heart failure (CHF). They exert beneficial hemodynamic effects by decreasing left ventricular filling pressure and systemic vascular resistance while modestly improving cardiac output. The improvement in left ventricular function caused by nitrates is the result of combined reduction in outflow resistance and mitral regurgitation, while decreased pericardial constraint and subendocardial ischemia may also contribute to the process. With continuous nitrate administration, complete arterial tolerance develops, while venous tolerance appears to be only partial. The major mechanism of tolerance is loss of vascular smooth muscle sensitivity to nitrates. An increase in total blood volume occurring during the first few hours of an acute administration may partly contribute to tolerance. The importance of reflex neurohumoral activation is controversial; although it may contribute to tolerance in CHF, its role does not appear to be major. Chronic continuous nitrate therapy in CHF improves submaximal and maximal exercise tolerance. In combination therapy with hydralazine, isosorbide dinitrate reduces mortality, although to a lesser extent than the angiotensin converting enzyme inhibitor enalapril. Intravenous or sublingual nitrates are first-line agents in the therapy of acute pulmonary edema. In severe CHF, refractory to standard medical therapy, a short course of intravenous nitroglycerin, with or without inotropic agents, can help break the vicious spiral of CHF. Because tolerance occurs without nitrate-free intervals and until an optimal schedule of administration is determined, it makes good sense to include a nightly nitrate-free interval when prescribing nitrates for CHF in order to maintain maximal benefit during the hours of activity.

Acute positive inotropic intervention: the catecholamines

The catecholamines remain a major therapeutic group in intensive cardiac care; this group of compounds evokes a positive inotropic response and vascular effects ranging from vasoconstriction to little net effect to vasodilatation. Hemodynamics and clinical guidelines now allow a proper selection of the optimal catecholamine. Additional mechanisms of action and a better understanding of the clinical application of this important drug group are continuing to unfold.

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)

Anesthetic management in the arterial switch "jatene" operation for transposition of the great arteries

The arterial switch "Jatene" operation for transposition of the great arteries (TGA) is an anatomic reconstruction at the level of the great arteries with reimplantation of the coronary arteries. The anesthetic management of 46 patients who underwent the Jatene operation between 1982 and 1985 was retrospectively reviewed. The mean age was 12.3 +/- 11.2 months (youngest: 4 days) and the mean body weight was 7.0 +/- 2.8 kg (smallest: 3.0 kg). Anesthesia was induced with ketamine in 35 patients, and maintained with morphine in 36 patients. Catecholamine (CA) drugs were given to 10 patients before cardiopulmonary bypass (CPB) and to all patients after CPB. In addition, nitroglycerin (NTG) was given to 13 patients during and after CPB. Platelets were given to prevent bleeding due to platelet damage caused by CPB. Six patients died, producing a mortality rate of 13%. Body weight, age, anesthetic agent, dose of CA, volume of blood loss, and duration of aortic cross-clamping, anesthesia, and operation were not significantly related to the deaths. Urinary output was significantly smaller (P < .05) in the patients who died. The LV/RV pressure ratio was as low as 0.625 and 0.645 in two of six deaths due to left ventricular hypoplasia. Severe pulmonary hypertension occurred in the postoperative period in two patients, and two patients had heart failure following a previous operation for coarctation or interruption of the aorta. Since hypotension during induction is detrimental in these cases, ketamine was commonly used as an induction agent. Morphine was chosen rather than fentanyl to avoid bradycardia. Administration of CA drugs produced an inotropic effect on the heart, and NTG helped maintain coronary blood flow and prevented pulmonary hypertension. There were no anesthetic deaths as judged by both the surgeons and anesthesiologists.

The rational selection of inotropic drugs in cardiac surgery

Despite improvements in surgical technique and intraoperative myocardial protection, certain patients have need for inotropic drug support after cardiac surgery. This review examines drugs that are currently in use for inotropic support of the heart, including calcium, epinephrine, dopamine, dobutamine, isoproterenol, and amrinone. Patient factors that may have an impact on the selection of appropriate drugs are also examined. Application of these data to specific patients must be guided by the particular hemodynamic derangements present. Careful analysis of the specific hemodynamic disorder and tailoring of inotropic therapy to these abnormalities are crucial. Such a rational approach to the selection of inotropic agents requires continuous hemodynamic assessment and recognition that the patient's condition and needs may change rapidly early after heart surgery dictating adjustment of subsequent therapy.

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)

Hemodynamic studies and response to a combined therapy of nitroglycerin ointment and dopamine in patients with acute myocarditis

Left ventricular performance was assessed in ten patients with acute myocarditis during the acute stage (within the first 3 days after the onset of cardiac symptoms) and during the convalescent phase (3-5 weeks later). In nine, the diagnosis was confirmed by endomyocardial biopsy during the acute stage, when left ventricular function was markedly reduced, i.e., cardiac index 1.53 +/- 0.33 l/min/m2 (mean +/- SD), left ventricular stroke work index 14.1 +/- 3.9 g/beat/m2, pulmonary capillary pressure 25.9 +/- 4.3 mm Hg, and systemic vascular resistance 27.9 +/- 9.4 R units. During convalescence, seven patients improved clinically with normal cardiac function and in three it remained impaired. Cardiovascular response to nitroglycerin ointment in three patients and a combination of dopamine and nitroglycerin ointment in five were compared. Nitroglycerin ointment reduced pulmonary capillary pressure by an average of 28.5% (P less than 0.05) and systemic vascular resistance by 26.8%, while the cardiac index increased by 34.1% (P less than 0.05) and left ventricular stroke work index by 30.3% (P less than 0.01). The combined therapy was more effective, with a reduction of pulmonary capillary pressure by 30.4% (P less than 0.05) and systemic vascular resistance by 27.5% (P less than 0.05), accompanying an increase in cardiac index by 53.5% (P less than 0.005) and left ventricular stroke work index by 63.5% (P less than 0.01), with little change in the double products. This study suggests that serial hemodynamic monitoring accurately evaluates cardiac function, selection of appropriate therapy, and the hemodynamic effects of treatment in patients with acute myocarditis.(ABSTRACT TRUNCATED AT 250 WORDS)

The haemodynamic responses to incremental doses of intravenous nitroglycerin in left ventricular failure

The effects of incremental dose infusions of nitroglycerin, 10-160 micrograms/min, on pulmonary capillary wedge pressure and other haemodynamic variables have been studied in patients with left ventricular failure. Intravenous (IV) nitroglycerin caused a dose-related improvement in myocardial performance, with significant reductions in the raised pulmonary capillary wedge pressure and systemic vascular resistance. At the lowest dose of infusion only the venodilator action of nitroglycerin was apparent. From 40-160 micrograms/min the associated arteriolar dilatation was associated with a consistent improvement in myocardial performance.

Long-term hemodynamic effects of prenalterol in patients with severe congestive heart failure

In a controlled, randomized, double-blind study we investigated the long-term effects of the beta 1-adrenoceptor agonist prenalterol in 16 patients with severe congestive heart failure (NYHA class III or IV). Previous to and 1 week, 3 months, and 6 months after continuous oral intake of 40 to 120 mg prenalterol a day, catheterization of the right heart combined with an ergometer test was carried out; M mode and two dimensional echocardiograms as well as systolic time intervals were also recorded. With prenalterol the heart rate increased within 1 week from 81 +/- 7 to 90 +/- 7 beats/min (mean +/- SD) (p less than .05) and remained increased after 3 months (93 +/- 9 beats/min, p less than .01) and 6 months (91 +/- 6 beats/min, p less than .05). After 1 week the cardiac index rose from 2.7 +/- 0.7 to 3.3 +/- 0.7 l/min/m2 (p less than .01), and after 3 and 6 months it fell again to 3.0 +/- 0.9 l/min/m2 and 2.9 +/- 0.7 l/min/m2, respectively. In the ergometer test the improvement in performance was not significant. The mean velocity of circumferential fiber shortening initially increased from 0.58 +/- 0.20 to 0.79 +/- 0.28 circumferences/sec (p less than .01), but dropped after 3 months to 0.62 +/- 0.31 circumferences/sec. The ejection fraction determined from the two-dimensional echocardiogram rose after 1 week from 20 +/- 10 to 27 +/- 12% (p less than .05), but decreased again after 3 months (23 +/- 11%) and 6 months (20 +/- 10%).(ABSTRACT TRUNCATED AT 250 WORDS)

Intravenous glyceryl trinitrate (nitroglycerin). A review of its pharmacological properties and therapeutic efficacy

The recently introduced preparation of intravenous glyceryl trinitrate (nitroglycerin) provides a rapid steady therapeutic blood concentration of nitrates during continuous infusion. Intravenous glyceryl trinitrate causes venodilation at low doses, but at higher doses dilates both arteries and veins. Its principal haemodynamic effects at therapeutic dosages include a decrease in blood pressure in preload (left ventricular filling pressure) and in determinants of afterload, and a decrease in myocardial oxygen demand. Human pharmacokinetic data are few and difficult to interpret due to wide interstudy and interindividual variation. There is no close correlation between infusion rate, blood concentration and haemodynamic effects. The nature of the patient population treated with intravenous glyceryl trinitrate has largely precluded the use of a placebo, but in open trials the drug has been used successfully in the treatment of unstable angina, left ventricular failure accompanying acute myocardial infarction and in the control of hypertension associated with cardiac surgery at dosages titrated to achieve a specific end-point. Favourable haemodynamic responses have been achieved in very short term studies in congestive heart failure, and preliminary studies suggest that institution of intravenous glyceryl trinitrate early after acute myocardial infarction may limit ischaemic damage. However, use of the drug in acute myocardial infarction remains controversial. Intravenous glyceryl trinitrate is generally well tolerated, although hypotension and headache occur occasionally, and sinus tachycardia and bradycardia less frequently. Careful titration of dosage is required (beginning at 5 micrograms/min), and if the infusion sets contain polyvinylchloride, the delivered dose is lower than that calculated, because of adsorption of glyceryl trinitrate onto the plastic tubing.

Beneficial effects of dopamine combined with intravenous nitroglycerin on hemodynamics in patients with severe left ventricular failure

Hemodynamic effects of dopamine and intravenous nitroglycerin alone, and in combination, were studied in 27 patients with severe left ventricular failure. Dopamine alone increased cardiac index from 1.8 to 2.5 l/min/m2 but also increased wedge pressure from 24 to 30 mm Hg and heart rate from 88 to 101 beats/min. Arterial oxygen saturation fell from 92% to 87% (p less than .001). Nitroglycerin alone had a lesser effect on cardiac index (1.8 to 2.2 l/min/m2) but decreased wedge pressure from 26 to 16 mm Hg and heart rate from 91 to 86 beats/min. Arterial oxygen saturation fell from 91% to 90% (NS). Combined dopamine and nitroglycerin administration resulted in optimal hemodynamics, with cardiac index of 2.9 l/min/m2, wedge pressure of 17 mm Hg, and heart rate of 96 beats/min. Arterial oxygen saturation remained low at 88% in spite of the reduction in left ventricular filling pressure, which probably reflects increased intrapulmonary right-to-left shunting coupled with increased pulmonary blood flow. These results suggest that the combination of dopamine with intravenous nitroglycerin should be considered for patients with severe left ventricular dysfunction who require temporary pharmacologic support.

The use of intravenous nitroglycerin in cardiovascular disease

The development of an intravenous form of nitroglycerin has further enhanced the role of nitrates in the therapy of cardiovascular disorders. This new preparation permits prompt initiation of therapy and rapid attainment of high systemic levels; because of its short half-life, rapid dose titration is both feasible and safe. The antianginal effects of intravenous nitroglycerin are useful in the treatment of coronary vasospasm and unstable angina pectoris. Its hemodynamic effects are of benefit in the therapy of congestive heart failure and in the control of peri-operative hypertension. Recent data suggest that, with appropriate monitoring, intravenous nitroglycerin can be safely administered to patients with evolving myocardial infarction to reduce the extent of myocardial damage.