Acute heart failure: a novel approach to its pathogenesis and treatment

Acute heart failure (HF) is one of the most common syndromes in emergency medicine, however, its exact pathogenesis has remained largely unknown. Based on clinical and hemodynamic data we have sub-divided acute HF into four syndromes: cardiogenic shock, pulmonary edema, hypertensive crisis and exacerbated HF. Cardiogenic shock is caused by a severe reduction in cardiac power which is not met by an adequate increase in peripheral vascular resistance leading to significant decrease in blood pressure and end organ perfusion. Hence the treatment of cardiogenic shock should be directed at improving cardiac performance (by optimizing filling pressure, intra-aortic balloon pump and immediate revascularization) and administration of peripheral vasoconstrictors. The other acute HF syndromes (pulmonary edema, HTN crisis and exacerbated HF) are caused by a combination of progressive excessive vasoconstriction superimposed on reduced left ventricular functional reserve. The impaired cardiac power and extreme vasoconstriction induce a vicious cycle of afterload mismatch resulting in a dramatic reduction of CO and elevated left ventricular end diastolic pressure, which is transferred backwards to the pulmonary capillaries yielding pulmonary edema. Therefore, the immediate treatment of these acute HF syndromes should be based on the administration of strong, fast-acting intravenous vasodilators such as nitrates or nitroprusside. After initial stabilization, therapy should be directed at reducing recurrent episodes of acute HF, by prevention of repeated episodes of excessive vasoconstriction along with efforts to optimize cardiac function.

Comparison and evaluation of antimicrobial susceptibility testing of enterococci performed in accordance with six national committee standardized disk diffusion procedures

Studies were conducted to compare and evaluate antimicrobial susceptibility test results for enterococci obtained by six national committee disk diffusion procedures. Variations in the incidence of isolates in resistance categories and errors were associated with the use of ciprofloxacin, gentamicin, nitrofurantoin, rifampin, and teicoplanin in a number of committee procedures. Results indicate that laboratories performing disk diffusion antimicrobial susceptibility testing may have problems correctly identifying resistance in enterococci with agents used to combat infections and that it may be difficult to compare resistance data for surveillance purposes.

Delayed thrombocytopenia following abciximab therapy

Inhibitors of glycoprotein (GP) IIb/IIIa are currently approved for the treatment of acute coronary syndromes and during performance of percutaneous coronary interventions (PCIs). More than 500 000 patients annually undergo PCIs in the USA alone. Of these, 35% are receiving GPIIb/IIIa inhibitors. Currently, three different intravenous GPIIb/IIIa inhibitors are commercially available. Profound thrombocytopenia occurs almost exclusively with abciximab. Usually thrombocytopenia develops within 24 hours following abciximab administration. This paper describes three patients who developed delayed profound thrombocytopenia, occurring five days following abciximab therapy. These cases of thrombocytopenia were self-limited and reversible. Absence of serious bleeding complications was noted. The pathophysiology, differential diagnosis, natural history and management of the coronary patients with abciximab-induced thrombocytopenia are discussed.

Tezosentan (an intravenous endothelin receptor A/B antagonist) reduces peripheral resistance and increases cardiac power therefore preventing a steep decrease in blood pressure in patients with congestive heart failure

OBJECTIVE

This study investigated the effect of tezosentan (an intravenous endothelin-1 receptor antagonist) on vascular resistance and cardiac function and determined the dose response in patients with stable congestive heart failure (CHF) due to left ventricular systolic dysfunction.

METHODS

In a double-blind fashion, tezosentan or placebo were administered in ascending doses (5, 20, 50, 100 mg h(-1)) to 38 CHF (NYHA class III) patients with ejection fraction <or=35%, cardiac index <or=2.7 l min(-1) m(-2) and pulmonary capillary wedge pressure >or=15 mmHg. Systemic vascular resistance index (SVRi) was estimated as mean arterial blood pressure [(MAP-right atrial pressure)/cardiac index (CI)]. Cardiac function was assessed as cardiac power index (Cpi), calculated as pressure x flow (MAP x CI), where MAP represents pressure and CI represents cardiovascular flow.

RESULTS AND DISCUSSION

Compared to the placebo, tezosentan induced a dose-dependent decrease in SVRi (-32%), an increase in Cpi (+20%) and a small decrease in MAP (-9%). By contrast, patients treated with nitrate vasodilators or nesiritide (a natriuretic peptide) showed a decrease in SVRi not accompanied by a significant increase in Cpi leading to a steep decrease in MAP.

CONCLUSIONS

The use of Cpi in the assessment of the hemodynamic effects of tezosentan, provides a useful alternative characterization of the complex influences of vasodilators on cardiac function in patients with CHF.

The dual endothelin receptor antagonist tezosentan acutely improves hemodynamic parameters in patients with advanced heart failure

BACKGROUND

Endothelin-1, a potent vasoconstrictor, is elevated in congestive heart failure and is postulated to play a major role in the pathogenesis of the disease. Endothelin receptor antagonism may be a specific therapeutic approach. This study was designed to determine the effective dosage range, hemodynamic effects, and tolerability of tezosentan, an intravenous dual endothelin receptor antagonist, in patients with advanced heart failure.

METHODS

This randomized, double-blind, placebo-controlled multicenter trial enrolled 38 patients with symptomatic stable heart failure (New York Heart Association class III, left ventricular ejection fraction <35%) undergoing right heart catheterization. Patients were equally randomized to a 4-hour intravenous infusion of placebo or tezosentan in ascending doses (5, 20, 50, and 100 mg over 1 hour each). Angiotensin-converting enzyme inhibitors and diuretics were withheld 24hours before the study. Hemodynamics were measured during and for 4 hours after the infusion.

RESULTS

Compared with placebo, tezosentan treatment produced a significant increase in cardiac index (treatment difference 0.59 L/min/m(2), P =.0001) and decreases in pulmonary and systemic vascular resistances (P </=.01) without changes in heart rate. Consistently greater decreases in pulmonary capillary wedge pressure, mean right atrial pressure, and pulmonary and arterial pressures with tezosentan did not reach statistical significance. Hemodynamic changes were dose dependent with maximal effects at 20 and 50 mg per hour. Tezosentan was well tolerated. Despite increased endothelin-1 concentrations, hemodynamic rebound was not observed.

CONCLUSION

Tezosentan rapidly and dose dependently improved hemodynamics. The favorable effects on cardiac index and pulmonary and systemic vascular resistances without changes in heart rate may be beneficial in the treatment of acute heart failure.

Radiation oncology practice accreditation

The practice accreditation program of The American College of Radiology is described. Practice accreditation constitutes a facile mechanism to accomplish external quality assurance and to assess compliance with recognized standards. The process of accreditation includes critical review of each radiation therapy facility, the technical staff, all quality assurance procedures, medical physics staff, nursing and physician personnel as well as a whole host of other items, the most important of which is meticulous examination of selected patient charts. In the appendix, standards developed by the American College of Radiation Oncology, are reported.

A prospective study of posttraumatic stress symptoms and nonadherence in survivors of a myocardial infarction (MI)

We examined a novel hypothesis that links symptoms of MI-related posttraumatic stress disorder (PTSD) to nonadherence. According to this hypothesis, patients who are traumatized by their medical illness do not take their medications as prescribed. As a part of the avoidance dimension of PTSD, patients who are traumatized may avoid being reminded of the MI by not taking the medication. MI survivors were prospectively followed for 6 months to 1 year. Adherence was assessed by pill count of Captopril. Demographic variables, medical risk factors, PTSD, and other psychiatric symptom dimensions were evaluated during follow-up. One hundred two of 140 recruited patients completed follow-up. Nonadherence to Captopril was associated with poor medical outcome (r=.93, P=.006). Above-Threshold PTSD symptoms were associated with nonadherence to medications (P=.05). No other psychiatric symptom dimensions were independently associated with nonadherence. Nonadherence to medications predicts adverse outcome during the first year after an acute MI. Nonadherence is associated with PTSD symptoms, which may either be a marker for or a cause of nonadherence. Treatment of PTSD may prove to be a useful approach for improving adherence.

Pulmonary edema: new insight on pathogenesis and treatment

Pulmonary edema is one of the most serious and life-threatening situations in emergency medicine. Lately it has become apparent that in most cases pulmonary edema is not caused by fluid accumulation but rather fluid redistribution that is directed into the lungs because of heart failure. Based on a series of recently published studies, we propose that often the pathogenesis of pulmonary edema is related to a combination of marked increase in systemic vascular resistance superimposed on insufficient systolic and diastolic myocardial functional reserve. This resistance results in increased left ventricular diastolic pressure causing increased pulmonary venous pressure, which yields a fluid shift from the intravascular compartment into the pulmonary interstitium and alveoli, inducing the syndrome of pulmonary edema. Therefore, the emphasis in treating pulmonary edema has shifted from diuretics (ie, furosemide) to vasodilators (ie, high-dose nitrates) combined with noninvasive positive airway pressure ventilation and rarely inotropes. New classes of drugs that are currently being investigated for treating decompensated heart failure such as natriuretic peptides, calcium promoters, and endothelin antagonist are also being assessed for treating pulmonary edema. This review will explore this new hypothesis put forward to explain the pathogenesis of pulmonary edema and the evolving management strategies.

Adherence mechanisms of Candida albicans

The yeast Candida albicans is an opportunistic fungal pathogen that is capable of inducing a range of superficial and systemic diseases in the immunocompromised host. Although it displays a variety of virulence factors, one--the ability to adhere to host tissue--is considered essential in the early stages of colonisation and tissue invasion. Adherence is achieved by a combination of specific (ligand-receptor interactions) and non-specific (electrostatic charge, van der Waals forces) mechanisms which allow the yeast to attach to a wide range of tissue types and inanimate surfaces. Conventional methods for treating disease cause by C. albicans rely upon the use of antifungal drugs designed to kill the yeast or arrest its growth. An alternative approach, aimed at disrupting the adherence of the yeast to host tissue in cases of superficial infection, may have potential for controlling disease, particularly in situations where the unattached fungal cell can be removed from the affected site, either by the flushing action of the oropharynx or by the production of mucus in the vagina.

High-dose intravenous isosorbide-dinitrate is safer and better than Bi-PAP ventilation combined with conventional treatment for severe pulmonary edema

OBJECTIVE

To determine the feasibility, safety and efficacy of bilevel positive airway ventilation (BiPAP) in the treatment of severe pulmonary edema compared to high dose nitrate therapy.

BACKGROUND

Although noninvasive ventilation is increasingly used in the treatment of pulmonary edema, its efficacy has not been compared prospectively with newer treatment modalities.

METHODS

We enrolled 40 consecutive patients with severe pulmonary edema (oxygen saturation <90% on room air prior to treatment). All patients received oxygen at a rate of 10 liter/min, intravenous (IV) furosemide 80 mg and IV morphine 3 mg. Thereafter patients were randomly allocated to receive 1) repeated boluses of IV isosorbide-dinitrate (ISDN) 4 mg every 4 min (n = 20), and 2) BiPAP ventilation and standard dose nitrate therapy (n = 20). Treatment was administered until oxygen saturation increased above 96% or systolic blood pressure decreased to below 110 mm Hg or by more than 30%. Patients whose conditions deteriorated despite therapy were intubated and mechanically ventilated. All treatment was delivered by mobile intensive care units prior to hospital arrival.

RESULTS

Patients treated by BiPAP had significantly more adverse events. Two BiPAP treated patients died versus zero in the high dose ISDN group. Sixteen BiPAP treated patients (80%) required intubation and mechanical ventilation compared to four (20%) in the high dose ISDN group (p = 0.0004). Myocardial infarction (MI) occurred in 11 (55%) and 2 (10%) patients, respectively (p = 0.006). The combined primary end point (death, mechanical ventilation or MI) was observed in 17 (85%) versus 5 (25%) patients, respectively (p = 0.0003). After 1 h of treatment, oxygen saturation increased to 96 +/- 4% in the high dose ISDN group as compared to 89 +/- 7% in the BiPAP group (p = 0.017). Due to the significant deterioration observed in patients enrolled in the BiPAP arm, the study was prematurely terminated by the safety committee.

CONCLUSIONS

High dose ISDN is safer and better than BiPAP ventilation combined with conventional therapy in patients with severe pulmonary edema.

Minimal heparinization in coronary angioplasty--how much heparin is really warranted?

The purpose of the study was to assess the results of percutaneous transluminal coronary angioplasty (PTCA), performed with a single intravenous bolus of 2,500 U of heparin, in a nonemergency PTCA cohort. Three hundred of 341 consecutive patients (87.9%) undergoing PTCA were prospectively enrolled in the study. They received heparin, 2,500-U intravenous bolus, before PTCA, with intention of no additional heparin administration. Patient and lesion characteristics as well as PTCA results were evaluated independently by 2 physicians. Patients were followed up by structured telephone questionnaires at 1 and 6 months after PTCA. Mean activated clotting time obtained 5 minutes after heparin administration was 185+/-19 seconds (range 157 to 238). There were 3 (1%) in-hospital major adverse cardiovascular events: 2 deaths (0.66%), 1 (0.33%) Q-wave myocardial infarction. Emergency coronary surgery and stroke were not reported. Six patients (2%) experienced abrupt coronary occlusion within 14 days after PTCA, warranting repeat target vessel revascularization. Angiographic and clinical success were achieved in 96% and 93.3%, respectively. No bleeding or vascular complications were recorded. Six-month follow-up (184 patients) revealed 3 cardiac deaths (1 arrhythmic, 2 after cardiac surgery), 1 Q-wave myocardial infarction, and 9.7% repeat target vessel revascularization. This study suggests that very low doses of heparin and reduced activated clotting time target values are safe in non-emergency PTCA, and can reduce bleeding complications, hospital stay, and costs. Larger, randomized, double-blind heparin dose optimization studies need to confirm this notion.

L-NMMA (a nitric oxide synthase inhibitor) is effective in the treatment of cardiogenic shock

BACKGROUND

The objective was to assess the safety and efficacy of L-NMMA in the treatment of cardiogenic shock.

METHODS

We enrolled 11 consecutive patients with cardiogenic shock that persisted after >24 hours from admission, despite coronary catheterization and primary percutaneous transluminal coronary revascularization, when feasible, and treatment with mechanical ventilation, intraaortic balloon pump (IABP), and high doses of catecholamines. L-NMMA was administered as an IV bolus of 1 mg/kg and continuous drip of 1 mg. kg(-1). h(-1) for 5 hours. Treatment with catecholamines, mechanical ventilation, and IABP was kept constant throughout the study.

RESULTS

Within 10 minutes of L-NMMA administration, mean arterial blood pressure (MAP) increased from 76+/-9 to 109+/-22 mm Hg (+43%). Urine output increased within 5 hours from 63+/-25 to 156+/-63 cc/h (+148%). Cardiac index decreased during the steep increase in MAP from 2. 0+/-0.5 to 1.7+/-0.4 L/(min. m(2)) (-15%); however, it gradually increased to 1.85+/-0.4 L/(min. m(2)) after 5 hours. The heart rate and the wedge pressure remained stable. Twenty-four hours after L-NMMA discontinuation, MAP (+36%) and urine output (+189%) remained increased; however, cardiac index returned to pretreatment level. No adverse events were detected. Ten out of eleven patients could be weaned off mechanical ventilation and IABP. Eight patients were discharged from the coronary intensive care unit, and seven (64%) were alive at 1-month follow-up.

CONCLUSIONS

L-NMMA administration in patients with cardiogenic shock is safe and has favorable clinical and hemodynamic effects.

Development of an insect model for the in vivo pathogenicity testing of yeasts

Conventional in vivo assays to determine the relative pathogenicity of yeast isolates rely upon the use of a range of mammalian species. The purpose of the work presented here was to investigate the possibility of using an insect (Galleria mellonella) as a model system for in vivo pathogenicity testing. The haemolymph of G. mellonella larvae was inoculated with PBS containing different concentrations of stationary phase yeasts of the genus Candida by injection at the last pro-leg. Larvae were incubated at 30 degrees C and monitored over 72 hours. Results indicate that G. mellonella can be killed by the pathogenic yeast Candida albicans and by a range of other Candida species but not to a significant extent by the yeast Saccharomyces cerevisiae. The kill kinetics for larvae inoculated with clinical and laboratory isolates of C. albicans indicate the former class of isolates to be more pathogenic. Differences in the relative pathogenicity of a range of Candida species may be distinguished using G. mellonella as a model. This work indicates that G. mellonella may be employed to give results consistent with data previously obtained using mammals in conventional in vivo pathogenicity testing. Larvae of G. mellonella are inexpensive to culture, easy to manipulate and their use may reduce the need to employ mammals for routine in vivo pathogenicity testing with a concomitant reduction in mammalian suffering.

Conversion of recent onset paroxysmal atrial fibrillation to normal sinus rhythm: the effect of no treatment and high-dose amiodarone. A randomized, placebo-controlled study

BACKGROUND

Spontaneous conversion of recent onset paroxysmal atrial fibrillation to normal sinus rhythm occurs commonly and is not affected by low-dose amiodarone treatment.

METHODS

In a randomized, placebo-controlled trial of 100 patients with paroxysmal atrial fibrillation of recent onset (<48 h) we compared the effects of treatment with continuous intravenous amiodarone 125 mg per hour (total 3 g) and intravenous placebo. Patients in the placebo group who did not convert to normal sinus rhythm within 24 h were started on amiodarone therapy.

RESULTS

Conversion to normal sinus rhythm occurred within 24 h in 32 of 50 patients (64%) in the placebo group, most of whom converted within 8 h. Lower conversion rates were observed in patients with hypertension, ischaemic heart disease or congestive heart failure and in patients with echocardiographic findings of left atrial diameter above 45 mm, ejection fraction below 45% or significant mitral regurgitation. However, in most patients these clinical or echocardiographic risk factors of decreases in conversion rate were not present. In such patients the spontaneous conversion rate was approximately 90%. The conversion rate during 24 h of treatment in the amiodarone group was 92% (P=0.0017, compared to the placebo group). In this group, the conversion rate was largely unaffected by baseline characteristics. Of the 18 patients who did not convert with placebo, 15 (85%) converted after being crossed over to amiodarone. All patients not responding to high-dose amiodarone were in chronic atrial fibrillation within 1 month. In patients still in atrial fibrillation after 8 h of treatment, the pulse rate decreased significantly more in the amiodarone as compared to the placebo group (83+/-15 vs 114+/-20 beats. min(-1), P=0.0014).

CONCLUSION

The spontaneous conversion of recent onset paroxysmal atrial fibrillation is high and approaches 90% in specific clinical and echocardiographically defined subgroups. Intravenous high-dose amiodarone safely facilitates conversion of paroxysmal atrial fibrillation. However, such treatment should be reserved for patients with unfavourable risk factor profiles, not converting during 8 h of observation or requiring rate control.

Usefulness of losartan, captopril, and furosemide in preventing nitrate tolerance and improving control of unstable angina pectoris

Sixty consecutive normotensive patients with unstable angina pectoris, who were on continuous intravenous isosorbide dinitrate (ISDN) treatment and had not previously received angiotensin II receptor antagonists, angiotensin-converting enzyme (ACE) inhibitors, or diuretics were randomly assigned to treatment groups receiving intravenous ISDN for 72 hours. No additional treatment was given to group A (n = 15). Captopril, in a test dose of 6.25 mg, and followed by 12.5 mg 3 times daily for 24 hours and 25 mg 3 times daily for the next 24 hours, was given to group B (n = 15). The same dose of captopril plus 40 mg of furosemide in the morning were given to group C (n = 15). Losartan, in a single dose of 25 mg/day and increased to 50 mg after 24 hours was given to group D (n = 15). Nitrate tolerance was evaluated at 24-hour intervals at trough levels of each of the drugs by administering intravenous ISDN (1 mg bolus dose every 4 minutes) and recording the total ISDN test dose required to decrease the mean arterial blood pressure by > or =10%. Treatment with continuous ISDN only (group A) induced nitrate tolerance. The ISDN (mean +/- SD) test dose was 3.5 +/- 1.8 mg at baseline, increasing to 4.9 +/- 2.4 mg at 24 hours, and 8.0 +/- 3.0 mg at 48 hours. The addition of increasing doses of captopril to the continuous ISDN treatment (group B) completely prevented nitrate tolerance. Losartan, however, did not attenuate nitrate tolerance at 24 hours and attenuated it only partially at 48 hours. The addition of furosemide to captopril had no further effect on nitrate tolerance. Of 15 patients in group A (ISDN only), 4 (27%) experienced recurrent ischemic events requiring urgent coronary catheterization. No such events were recorded in group B (captopril), but did occur in 1 patient in each of group C (captopril plus furosemide) and D (losartan) (p = 0.083). Thus, the addition of captopril to the ISDN treatment regimen prevented tolerance to nitrates and improved angina control with apparent safety. Losartan also decreased nitrate tolerance, although to a lesser extent, and also improved angina control. The addition of furosemide to captopril conferred no further benefit.

Monoclonal antibodies directed against extracellular matrix proteins reduce the adherence of Candida albicans to HEp-2 cells

The presence of the extracellular matrix (ECM) proteins collagen types I and IV, laminin and fibronectin on the surface of HEp-2 cells was confirmed by flow cytometry using monoclonal antibodies. Monoclonal antibodies directed against these ECM proteins reduced the adherence of C. albicans ATCC 44990 to HEp-2 cells, the greatest reductions being evident in assays which incorporated anti-collagen type IV monoclonal antibody. The ability of sugaramines to inhibit the adherence of C. albicans to a variety of cell types has been demonstrated previously and the most significant reduction in C. albicans-HEp-2 adherence was in assays which incorporated 0.2M galactosamine. The combination of anti-collagen IV monoclonal antibody and galactosamine reduced the adherence of C. albicans to HEp-2 cells by approximately 70% (p < 0.05).

High-dose nitrates in the immediate management of unstable angina: optimal dosage, route of administration, and therapeutic goals

Nitrates are commonly used for rapid relief of ischemia in the initial management of unstable angina. However, their optimal dosage, route of administration, and therapeutic goals have not been fully established. This study was conducted to determine the optimal dosage and mode of administration (intravenous bolus versus sublingual spray) of nitrates and the therapeutic goals of their use in the immediate management of unstable angina. In a single-center prospective trial, 72 consecutive patients with unstable angina accompanied by typical ST-segment depression on electrocardiogram were randomly assigned to receive isosorbide dinitrate either as repeated intravenous boluses or as sublingual sprays while being delivered to the hospital by a mobile intensive care unit. Optimal nitrate dosage was tailored to pain relief while monitoring mean blood pressure reduction to an optimal range (5% to 20%) without dosage restriction. The mean nitrate dosage needed for ischemia control during the first hour of treatment was 7.8 +/- 3.8 mg. Optimal blood pressure reduction was achieved by significantly more intravenously treated patients than sublingually treated patients (68% v 41%, P = .037). Intravenously treated patients also experienced a more pronounced therapeutic effect, as assessed by reduction in chest pain score (67% v 39%, P = .0004) and decrease in ST-segment depressions (57% v 27%, P = .004). These results show that higher doses of nitrates than previously recommended are required for ischemia control during the initial management of unstable angina. The use of repeated intravenous boluses is safe and more easily controlled and, therefore, more efficacious than sublingual sprays in inducing the maximal anti-ischemic effect while avoiding significant hypotension.

Randomised trial of high-dose isosorbide dinitrate plus low-dose furosemide versus high-dose furosemide plus low-dose isosorbide dinitrate in severe pulmonary oedema

BACKGROUND

Nitrates and furosemide, commonly administered in the treatment of pulmonary oedema, have not been compared in a prospective clinical trial. We compared the efficacy and safety of these drugs in a randomised trial of patients with severe pulmonary oedema and oxygen saturation below 90%.

METHODS

Patients presenting to mobile emergency units with signs of congestive heart failure were treated with oxygen 10 L/min, intravenous furosemide 40 mg, and morphine 3 mg bolus. 110 patients were randomly assigned either to group A, who received isosorbide dinitrate (3 mg bolus administered intravenously every 5 min; n=56) or to group B, who received furosemide (80 mg bolus administered intravenously every 15 min, as well as isosorbide dinitrate 1 mg/h, increased every 10 min by 1 mg/h; n=54). Six patients were withdrawn on the basis of chest radiography results. Treatment was continued until oxygen saturation was above 96% or mean arterial blood pressure had decreased by 30% or to below 90 mm Hg. The main endpoints were death, need for mechanical ventilation, and myocardial infarction. The analyses were by intention to treat.

FINDINGS

Mechanical ventilation was required in seven (13%) of 52 group-A patients and 21 (40%) of 52 group-B patients (p=0.0041). Myocardial infarction occurred in nine (17%) and 19 (37%) patients, respectively (p=0.047). One patient in group A and three in group B died (p=0.61). One or more of these endpoints occurred in 13 (25%) and 24 (46%) patients, respectively (p=0.041).

INTERPRETATION

High-dose isosorbide dinitrate, given as repeated intravenous boluses after low-dose intravenous furosemide, is safe and effective in controlling severe pulmonary oedema. This treatment regimen is more effective than high-dose furosemide with low-dose isosorbide nitrate in terms of need for mechanical ventilation and frequency of myocardial infarction.

Effects of captopril and enalapril on zinc metabolism in hypertensive patients

OBJECTIVE

To investigate the effect of chronic captopril and enalapril treatment on zinc metabolism in hypertensive patients by assessing zinc levels in serum, urine and monocytes.

METHODS

Patients with newly diagnosed essential hypertension were randomly divided into two treatment groups: those treated with captopril only (n = 16) and those treated with enalapril only (n = 18). Ten healthy subjects served as controls. Prior to the start of treatment and again 6 months later, zinc was assessed in the serum, in urine collected over 24 hours, and in peripheral blood monocytes.

RESULTS

Significant enhancement of 24-hour urinary zinc excretion (micrograms/24 hour) after 6 months of treatment was observed only in the captopril-treated group (p < 0.01). However, intramonocytic zinc levels decreased significantly in both of the treated groups over the same period (p < 0.01 and P < 0.04 in the captopril- and enalapril-treated groups, respectively).

CONCLUSION

Treatment of hypertensive patients with captopril or enalapril may result in zinc deficiency.

Increased toxicity of high-dose furosemide versus low-dose dopamine in the treatment of refractory congestive heart failure

OBJECTIVE

To evaluate the safety and efficacy of low-dose dopamine, high-dose furosemide, and their combination in the treatment of refractory congestive heart failure.

METHODS

Twenty consecutive patients with refractory congestive heart failure were randomized to receive intravenous low-dose (4 micrograms/kg/min) dopamine combined with low-dose (80 mg/day) oral furosemide (group A; n = 7), intravenous low-dose dopamine with medium-dose furosemide (5 mg/kg/day through continuous intravenous administration; group B; n = 7), or high-dose furosemide (10 mg/kg/day through continuous intravenous administration; group C; n = 6).

RESULTS

The three groups showed similar improvement in signs and symptoms of congestive heart failure, urinary output (2506 +/- 671 ml/24 hr, mean +/- SD) and weight loss (3.3 +/- 2.3 kg) after 72 hours of therapy. Mean arterial blood pressure (MAP) decreased by 14% +/- 8% and 15% +/- 6% in groups B and C, respectively, but increased by 4% +/- 15% in group A (p = 0.017). Renal function deteriorated significantly in groups B and C: creatinine clearance decreased by 41% +/- 23% and 42% +/- 23%, respectively, but increased by 14% +/- 35% in group A (p = 0.0074). MAP decrease was positively correlated with the decrease in creatinine clearance (r = 0.7; p = 0.0007). Patients in group B and C had more hypokalemia than group A. Two patients in group C sustained acute oliguric renal failure and one patient in group B died suddenly while sustaining severe hypokalemia.

CONCLUSION

Combined low-dose intravenous dopamine and oral furosemide have similar efficacy but induce less renal impairment and hypokalemia than higher doses of intravenous furosemide taken either alone or with low-dose dopamine. The renal impairment induced by intravenous furosemide is probably related to its hypotensive effect in patients with refractory congestive heart failure.