Angiotensin-converting enzyme inhibitors in cardiovascular anesthesia

Prolonged Postoperative Vasoplegia in Pediatric Patients on Chronic Angiotensin II Blocker Treatment

Prolonged postoperative vasoplegia is known to occur following cardiac surgery in patients on chronic angiotensin II receptor blocker (ARB) treatment in adults. The perioperative management of these drugs in the pediatric population is not well described and here we would like to highlight this fact. While ARBs are increasingly used in children and adolescents with hypertension, there is lack of data to guide optimal pre-surgical management in the pediatric age group. We report two cases of prolonged vasoplegia following cardiopulmonary bypass occurring in adolescent patients on chronic ARB therapy and the importance of cessation of these drugs preoperatively.

Influence of angiotensin-converting enzyme inhibitor enalaprilat on endothelial-derived substances in the critically ill

OBJECTIVE

To assess the effects of the angiotensin-converting enzyme inhibitor enalaprilat on endothelial cells in septic patients.

DESIGN

Prospective, randomized, placebo-controlled, blinded study.

SETTING

Clinical investigation on a surgical intensive care unit of a university hospital.

PATIENTS

Forty surgical septic patients (noncardiac/nonneurosurgical patients).

INTERVENTIONS

After inclusion in the study and after baseline data were obtained, either 0.25 mg/hr (enalaprilat group, n = 20) or saline solution as placebo (control group, n = 20) was continuously given and continued throughout the following 5 days.

MEASUREMENTS AND MAIN RESULTS

Extensive hemodynamic monitoring was carried out in all patients. Plasma concentrations of endothelin-1, angiotensin II, soluble thrombomodulin, and soluble adhesion molecules (endothelial leukocyte adhesion molecule-1, intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and granule membrane protein-140) were measured from arterial blood samples. All measurements were carried out before the start of the infusion ("baseline" values) and daily during the following 5 days. All endothelial-derived substances (thrombomodulin, endothelin-1, and all soluble adhesion molecules) were similarly increased beyond normal in both group. Endothelin-1 increased only in the untreated control patients (from 6.9 +/- 0.7 to 14.3 +/- 1.4 mg/mL). Soluble thrombomodulin increased in the untreated control patients (from 58 +/- 9 to 79 +/- 14 ng/mL [p < .05]), but significantly decreased in the enalaprilat-treated patients. Soluble adhesion molecules increased in the untreated control group (endothelial leukocyte adhesion molecule from 92 +/- 14 to 192 +/- 29 ng/mL; intercellular adhesion molecule-1 from 480 +/- 110 to 850 +/- 119 ng/ mL) and returned almost to normal values in the enalaprilat patients. The survival rate did not differ significantly between the two groups. Control patients developed severe sepsis and septic shock more often than the enalaprilat-treated group.

CONCLUSIONS

The complex pathogenesis of endothelial function abnormalities in sepsis may offer a large number of pharmacologic interventions. Administration of the angiotensin-converting enzyme inhibitor enalaprilat resulted in a reduced release of soluble endothelial-derived substances into the circulating blood, which may indicate an improved endothelial function. The specific actions of enalaprilat on the endothelium have to be elucidated in further studies.

The effects of preoperative therapy with angiotensin-converting enzyme inhibitors on clinical outcome after cardiovascular surgery

OBJECTIVE

To determine the effect of preoperative therapy with angiotensin-converting enzyme (ACE) inhibitors on clinical outcome after cardiovascular surgery.

STUDY

Inception cohort.

SETTING

A tertiary care 54-bed cardiothoracic ICU.

PATIENTS

All admissions to an ICU over a 42-month period after cardiovascular surgery.

INTERVENTION

Extraction of preoperative, operative, and ICU data from a database.

OUTCOME MEASURES

Incidence of acute organ dysfunction, length of mechanical ventilation, ICU stay, and death after cardiovascular surgery.

RESULTS

The study cohort consisted of four groups: normal or moderately impaired left ventricular function control (group A, n=6,400); normal or moderately impaired left ventricular function treated with ACE inhibitors (group B, n=1,375); severe left ventricular dysfunction control (group C, n=1,905); and severe left ventricular dysfunction treated with ACE inhibitors (group D, n=1,650). The incidence of three or more organ dysfunction was similar on comparison of group A vs group B (5% vs 6%) or group C vs group D (15% vs 13%). There were no differences in the total duration of mechanical ventilation or length of stay in the ICU in group A vs group B or group C vs group D. Death occurred in 2% of groups A and B, and at 6% in groups C and D. Preoperative severe left ventricular dysfunction in both groups C and D was associated with an increased incidence of three or more organ dysfunction, duration of mechanical ventilation, length of stay in ICU, and death after surgery. Multivariate analysis indicated that therapy with ACE inhibitors did not affect the clinical outcome after cardiovascular surgery.

CONCLUSION

Preoperative therapy with ACE inhibitors did not influence the clinical outcome after cardiac surgery. It is unlikely that therapy with ACE inhibitors can alter the clinical sequelae of cardiopulmonary bypass and cardiac surgical procedures performed in high-risk patients because of underlying severe left ventricular dysfunction.

Can clonidine, enoximone, and enalaprilat help to protect the myocardium against ischaemia in cardiac surgery?

OBJECTIVE

To evaluate whether clonidine, enoximone, and enalaprilat reduce ischaemia-related myocardial cell damage in cardiac surgery.

DESIGN

Prospective randomised controlled trial.

SETTING

Clinical investigation in a cardiac anaesthesia department of a university hospital.

PATIENTS

88 consecutive patients undergoing coronary artery bypass surgery.

INTERVENTIONS

After induction of anaesthesia patients continuously received the alpha 2 agonist clonidine (group 1, n = 22), the phosphodiesterase (PDE) III inhibitor enoximone (group 2, n = 22), the angiotensin converting enzyme (ACE) inhibitor enalaprilat (group 3, n = 22), or saline solution as placebo (control group, n = 22). The infusion was stopped immediately before the start of cardiopulmonary bypass.

MAIN OUTCOME MEASURES

The ST segment was analysed and the activity of creatine kinase isoenzyme MB (CKMB), cardiac troponin T (TnT), and the BB isoenzyme of glycogen phosphorylase (GPBB) were measured before the start of infusion (baseline), after weaning from cardiopulmonary bypass (CPB), at the end of surgery, 5 h after CPB, and on the morning of the first and third postoperative days.

RESULTS

Biometric data and time of cross-clamping were not significantly different in the four groups. Changes in the ST segment indicating ischaemia were least common in the enalaprilat group (P < 0.05). Postoperatively, CKMB activity was significantly higher in the clonidine and the control groups. Both new markers of myocardial cell damage increased more after CPB and postoperatively in the control patients (TnT peak: (mean (SD)) 3.99 (0.35) microgram/1; GPBB peak: 82 (15) ng/ml) and the clonidine-treated group (TnT peak: 3.80 (0.3) microgram/1; GPBB peak: 85 (14) ng/ml). Enalaprilat-treated patients showed the smallest overall changes in standard (CKMB) and new serological markers of myocardial ischaemia (TnT peak: 0.71 (0.1) microgram/1; GPBB peak: 44 (14) ng/ml).

CONCLUSIONS

In patients treated with enalaprilat before CPB, both new, more sensitive markers of ischaemic myocardial tissue damage increased significantly less than in an untreated control group. Those treated with enoximone also had lower plasma concentration of TnT and GPBB than the control group, whereas clonidine did not reduce the concentration of these markers of myocardial ischaemia. Pharmacological interventions, such as the continuous infusion of the ACE inhibitor enalaprilat, before start of CPB may help to protect the heart against ischaemia/reperfusion injury.

Cardiorespiratory effects of continuous i.v. administration of the ACE inhibitor enalaprilat in the critically ill

1. Cardiorespiratory effects of long-term, continuous i.v. administration of the ACE inhibitor enalaprilat were studied. 2. Forty-five consecutive critically patients suffering from trauma or postoperative complications were randomly separated into three groups (15 patients in each group) receiving either 0.25 mg h-1 or 0.50 mg h-1 enalaprilat, respectively, or saline solution as placebo (= control group). The infusion was continued for 5 days. 3. Haemodynamic and respiratory parameters were intensively monitored on admission to the intensive care unit (= 'baseline' values) and daily during the next 5 days. 4. Mean arterial blood pressure (MAP) decreased significantly only in the enalaprilat-treated patients, whereas heart rate (HR) remained unchanged in these patients. 5. Pulmonary capillary wedge pressure (PCWP) and pulmonary artery pressure (PAP) were decreased by enalaprilat (0.50 mg h-1: PAP (mean +/- s.d.) decreased from 28.0 +/- 4.1 to 24.0 +/- 3.0 mm Hg) and remained significantly lower than in the control group. In the untreated control group, cardiac index (CI), oxygen consumption (VO2I) and oxygen delivery (DO2I) significantly decreased, which was blunted by enalaprilat infusion. Oxygen extraction (O2-extr) increased in both enalaprilat groups (0.25 mg h-1: from 26.1 +/- 5.5 to 30.4 +/- 4.0%; 0.50 mg h-1: 25.2 +/- 5.6 to 30.9 +/- 4.4%) and decreased in the control patients. 6. Right ventricular haemodynamics improved by enalaprilat infusion (0.50 mg h-1: RVEF increased from 40.0 +/- 3.5 to 45.5 +/- 4.0%). Lactate plasma concentrations decreased in the group with 0.50 mg h-1 enalaprilat (from 1.9 +/- 1.0 to 1.3 +/- 0.3 mg dl-1) and increased in the control patients. 7. Continuous infusion of the ACE inhibitor enalaprilat exerted beneficial cardiorespiratory effects in the critically ill. The widespread common risk of altered perfusion with decreased CI, DO2, VO2, O2-extr and increased lactate concentration was blunted by enalaprilat infusion. 8. Although 0.5 mg h-1 enalaprilat was most effective, a dose of 0.25 mg h-1 also showed beneficial haemodynamic effects in the critically ill.

Influence of intravenous administration of angiotensin-converting enzyme inhibitor enalaprilat on cardiovascular mediators in cardiac surgery patients

The renin-angiotensin system (RAS) is important in controlling and maintaining cardiovascular homeostasis. In a randomized, prospective study, the response to intravenous (i.v.) administration of the angiotensin-converting enzyme (ACE) inhibitor enalaprilat (0.06 mg/kg) on important controllers of the circulation was investigated in 14 patients undergoing aortocoronary bypass grafting with a mean arterial blood pressure (MAP) > 85 mm Hg after induction of anesthesia. Fourteen patients received saline solution as placebo (control group). Endothelin (ET), atrial natriuretic peptide (ANP), catecholamine (epinephrine, norepinephrine) plasma levels, and ACE activity were measured from arterial blood sampled before injection of enalaprilat or NaCl solution (baseline values), 10 min and 30 min thereafter, immediately before the start of cardiopulmonary bypass (CPB), immediately after CPB, and at the end of surgery. MAP, heart rate (HR), cardiac index (CI), and systemic vascular resistance (SVR) were also monitored. ACE activity was similar at baseline in both groups; after i.v. injection of enalaprilat, it significantly decreased (from 35.1 +/- 11 to 4.4 +/- 1.0 U.min-1.L-1 30 min after injection) and remained reduced until the end of the operation (295 +/- 31 min after injection). ANP plasma levels were increased beyond normal (> 100 pg/mL) at baseline in both groups. They increased significantly in the control patients, but remained almost unchanged in the enalaprilat-treated patients within the entire study period. Plasma concentration of ET also increased only in the control group and was increased after CPB (8.6 +/- 1.2 pg/mL at the end of the operation).(ABSTRACT TRUNCATED AT 250 WORDS)