Mechanism of plasma catecholamine increases during coronary artery bypass and valve procedures

Association Between Intraoperative Landiolol Use and In-Hospital Mortality After Coronary Artery Bypass Grafting: A Nationwide Observational Study in Japan

BACKGROUND

Ischemic heart disease is a leading cause of death worldwide, and coronary artery bypass grafting (CABG) is a major treatment. Landiolol is an ultra-short-acting beta-antagonist known to prevent postoperative atrial fibrillation. However, the effectiveness of intraoperative landiolol on mortality remains unknown. This study aimed to evaluate the association between intraoperative landiolol use and the in-hospital mortality in patients undergoing CABG.

METHODS

To conduct this retrospective cohort study, we used data from the Japanese Diagnosis Procedure Combination inpatient database. All patients who underwent CABG during hospitalization between July 1, 2010, and March 31, 2020, were included. Patients who received intraoperative landiolol were defined as the landiolol group, whereas the other patients were defined as the control group. The primary outcome was in-hospital mortality. Propensity score matching was used to compare the landiolol and control groups.

RESULTS

In total, 118,506 patients were eligible for this study, including 25,219 (21%) in the landiolol group and 93,287 (79%) in the control group. One-to-one propensity score matching created 24,893 pairs. After propensity score matching, the in-hospital mortality was significantly lower in the landiolol group than that in the control group (3.7% vs 4.3%; odds ratio 0.85; 95% confidence interval 0.78 to 0.94; P = .010).

CONCLUSIONS

Intraoperative landiolol use was associated with decreased in-hospital mortality in patients undergoing CABG. Further randomized controlled trials are required to confirm these findings.

Reduction of postoperative nausea and vomiting risk in the second stage during bilateral total knee arthroplasty with a 1-week interval

PURPOSE

Total knee arthroplasty (TKA) is often performed sequentially on both sides during a single hospital stay. Patients who experience postoperative nausea and vomiting (PONV) after the first operation are concerned about PONV recurrence after the second operation. However, there are few studies regarding the incidence of PONV in staged bilateral TKA with a ≥ 1-week interval. This study aimed to identify the differences in (1) PONV incidence, (2) use of rescue antiemetics, and (3) the amount of opioid consumption between the first and second operations for staged bilateral TKA with a 1-week interval. Based on our anecdotal experience, the hypothesis of this study was that during staged bilateral TKA at a 1-week interval, the PONV incidence and rescue antiemetic requirement after the second operation will be lower than those after the first operation, regardless of opioid consumption.

METHODS

Fifty-eight consecutive patients who underwent staged bilateral TKA with a 1-week interval were retrospectively reviewed. All second-stage operations were performed with the same anaesthesia protocol and perioperative patient management protocol as the first-stage operation. PONV incidence was the primary outcome. The requirement for rescue antiemetic drugs and the amount of opioid consumption were secondary outcome variables. The outcome variables were recorded during three postoperative days (Days 0-2) for each stage and were compared between the first and second operations.

RESULTS

The incidence rates of nausea and vomiting on Day 0 (p = 0.001 and p = 0.004, respectively) and nausea on Day 1 (p = 0.008) were significantly lower after the second operation. Rescue antiemetic use on Day 0 was significantly lower after the second operation (p = 0.001). The total opioid consumption 72 h after surgery was significantly higher after the second operation (61.76 vs. 34.28 mg, p < 0.001).

CONCLUSION

During staged bilateral TKA with a 1-week interval, PONV incidence was lower after the second operation, even with increased opioid consumption.

LEVEL OF EVIDENCE

III.

Continuous Magnesium Infusion to Prevent Atrial Fibrillation After Cardiac Surgery: A Sequential Matched Case-Controlled Pilot Study

OBJECTIVE

The authors aimed to test whether a bolus of magnesium followed by continuous intravenous infusion might prevent the development of atrial fibrillation (AF) after cardiac surgery.

DESIGN

Sequential, matched, case-controlled pilot study.

SETTING

Tertiary university hospital.

PARTICIPANTS

Matched cohort of 99 patients before and intervention cohort of 99 consecutive patients after the introduction of a continuous magnesium infusion protocol.

INTERVENTIONS

The magnesium infusion protocol consisted of a 10 mmol loading dose of magnesium sulphate followed by a continuous infusion of 3 mmol/h over a maximum duration of 96 hours or until intensive care unit discharge.

MEASUREMENTS AND MAIN RESULTS

The study groups were balanced except for a lower cardiac index in the intervention cohort. The mean duration of magnesium infusion was 27.93 hours (95% confidence interval [CI]: 24.10-31.76 hours). The intervention group had greater serum peak magnesium levels: 1.72 mmol/L ± 0.34 on day 1, 1.32 ± 0.36 on day 2 versus 1.01 ± 1.14 and 0.97 ± 0.13, respectively, in the control group (p < 0.01). Atrial fibrillation occurred in 25 patients (25.3%) in the intervention group and 40 patients (40.4%) in the control group (odds ratio 0.49, 95% CI, 0.27-0.92; p = 0.023). On a multivariate Cox proportional hazards model, the hazard ratio for the development of AF was significantly less in the intervention group (hazard ratio 0.45, 95% CI, 0.26-0.77; p = 0.004).

CONCLUSION

The magnesium delivery strategy was associated with a decreased incidence of postoperative AF in cardiac surgery patients. These findings provide a rationale and preliminary data for the design of future randomized controlled trials.

Catecholamine stress alters neutrophil trafficking and impairs wound healing by β2-adrenergic receptor-mediated upregulation of IL-6

Stress-induced hormones can alter the inflammatory response to tissue injury, however, the precise mechanism by which epinephrine influences inflammatory response and wound healing is not well defined. Here we demonstrate that epinephrine alters the neutrophil (PMN)-dependent inflammatory response to a cutaneous wound. Using non-invasive real-time imaging of genetically-tagged PMNs in a murine skin wound, chronic, epinephrine-mediated stress was modeled by sustained delivery of epinephrine. Prolonged systemic exposure of epinephrine resulted in persistent PMN trafficking to the wound site via an IL-6 mediated mechanism, and this in turn impaired wound repair. Further, we demonstrate that β₂ adrenergic receptor-dependent activation of pro-inflammatory macrophages is critical for epinephrine-mediated IL-6 production. This study expands our current understanding of stress hormone-mediated impairment of wound healing and provides an important mechanistic link to explain how epinephrine stress exacerbates inflammation via increased number and lifetime of PMNs.

Cardiac adrenergic control and atrial fibrillation

Atrial fibrillation (AF) is the most common cardiac arrhythmia, and it causes substantial mortality. The autonomic nervous system, and particularly the adrenergic/cholinergic balance, has a profound influence on the occurrence of AF. Adrenergic stimulation from catecholamines can cause AF in patients. In human atrium, catecholamines can affect each of the electrophysiological mechanisms of AF initiation and/or maintenance. Catecholamines may produce membrane potential oscillations characteristic of afterdepolarisations, by increasing Ca(2+) current, [Ca(2+)](i) and consequent Na(+)-Ca(2+) exchange, and may also enhance automaticity. Catecholamines might affect reentry, by altering excitability or conduction, rather than action potential terminal repolarisation or refractory period. However, which arrhythmia mechanisms predominate is unclear, and likely depends on cardiac pathology and adrenergic tone. Heart failure (HF), a major cause of AF, causes adrenergic activation and adaptational changes, remodelling, of atrial electrophysiology, Ca(2+) homeostasis, and adrenergic responses. Chronic AF also remodels these, but differently to HF. Myocardial infarction and AF cause neural remodelling that also may promote AF. beta-Adrenoceptor antagonists (beta-blockers) are used in the treatment of AF, mainly to control the ventricular rate, by slowing atrioventricular conduction. beta-Blockers also reduce the incidence of AF, particularly in HF or after cardiac surgery, when adrenergic tone is high. Furthermore, the chronic treatment of patients with beta-blockers remodels the atria, with a potentially antiarrhythmic increase in the refractory period. Therefore, the suppression of AF by beta-blocker treatment may involve an attenuation of arrhythmic activity that is caused by increased [Ca(2+)](i), coupled with effects of adaptation to the treatment. An improved understanding of the involvement of the adrenergic system and its control in basic mechanisms of AF under differing cardiac pathologies might lead to better treatments.

Cibenzoline attenuates systolic anterior motion of the mitral valve after mitral valvoplasty

We report a patient in whom severe hemodynamic instability occurring after mitral valvoplasty (MVP) was successfully treated with cibenzoline. Left ventricular outflow tract obstruction (LVOTO) with mitral regurgitation (MR) resulting from the systolic anterior motion (SAM) of the mitral valve that occurs after MVP often leads to hemodynamic collapse. Patients who develop SAM after MVP have been managed with intravenous volume loading, reduction/discontinuation of inotropic drugs, and with increased afterload, but these strategies were often ineffective. Cibenzoline decreased myocardial contraction, attenuated SAM, and improved hemodynamics in our patient. We recommend that cibenzoline be administered before further surgical manipulation is considered for patients who develop SAM after MVP.

Cardiopulmonary bypass in infants and children

Cardiopulmonary bypass (CPB) systems have evolved from futuristic visions of surgical pioneers to a safe and efficient tool in the therapy of treatment of cardiac disorders. There are many significant differences in the physiology between neonates and adult patients. There are currently very few congenital cardiac malformations that cannot be addressed effectively with surgical therapy. Yet, the necessity of CPB in the repair of these patients can still result in significant morbidity. A clearer understanding of the effects of CPB, hypothermia, and circulatory arrest is evolving and there is a considerable amount of research in these areas. It seems likely that modification of current CPB systems, minimization of exposure, and surgical techniques to avoid or limit the adverse effects may reduce mortality and morbidity in the future. The problems faced in these complex patients and procedures require that infant and neonatal cardiac surgery be performed in specialized centers with a multidisciplinary approach and specialized personnel. Future improvements in technology will likely result in improved long term outcome for children with congenital cardiac disease. Copyright 2000 by W.B. Saunders Company

Influence of Vasodilator Drugs on Perioperative Blood Pressure

Survey results are given of the incidence and the etiology of perioperative hypertension in patients sub jected to coronary artery surgery. Over the years, numer ous types of antihypertensives have been used for intravenous administration with the aim of preventing or treating perioperative hypertension. Nitrovasodilator compounds such as sodium nitroprusside and nitroglyc erin (NTG), a few calcium antagonists (nifedipine, nicar dipine and isradipine), the short-acting β-blocker esmo lol, clonidine, and the multifactorial compounds labetalol and ketanserin are discussed in detail. Perioperatively, there is an increasing level of plasma catecholamines, causing α-adrenoceptor stimulation. This indicates that α-adrenoceptor blockade with appropriate antagonists is a logical approach for the treatment of perioperative hypertension. For this reason, the multifactorial agent urapidil, which is an α-adrenoceptor blocker and a 5-HT1A agonist, is discussed extensively.

A randomized multicenter double-blind comparison of urapidil and ketanserin in hypertensive patients after coronary artery surgery

OBJECTIVES

To compare the hemodynamic responses, safety, and efficacy of urapidil and ketanserin in hypertensive patients after coronary artery surgery.

DESIGN

Randomized double-blind study.

SETTING

Multi-institutional.

PARTICIPANTS

One hundred twenty-two patients undergoing elective coronary artery surgery.

INTERVENTIONS

When hypertension (defined as mean arterial pressure > 85 mmHg) developed within the first 2 hours after arrival in the intensive care unit, patients received urapidil (n = 62) or ketanserin (n = 60) to reach a mean arterial pressure between 65 and 75 mmHg. Urapidil was administered by repeated bolus injections (25 to 125 mg) followed by a continuous infusion of maximally 50 micrograms/kg/min. Ketanserin was administered by repeated bolus injections (10 to 50 mg) followed by a continuous infusion of maximally 4.0 micrograms/kg/min.

MEASUREMENTS AND MAIN RESULTS

A complete hemodynamic profile was determined at baseline and at 30 and 60 minutes after start of study medication. In the urapidil group, mean arterial pressure (+/-SD) decreased significantly from 100.6 +/- 12.4 mmHg at baseline to 74.6 +/- 12.1 mmHg at 30 minutes and 73.5 +/- 13.8 mmHg at 60 minutes. In the ketanserin group, mean arterial pressure decreased significantly from 98.7 +/- 10.7 mmHg at baseline to 83.5 +/- 16.8 mmHg at 30 minutes and 83.1 +/- 15.3 mmHg at 60 minutes. Between the groups, there was a significant difference in the degree of lowering mean arterial pressure at 30 and 60 minutes. Heart rate increased significantly by 5.8 +/- 12.7 (30 minutes) and 8.6 +/- 16.5 (60 minutes) beats/min in the ketanserin group. In the urapidil group, no changes in heart rate occurred. Cardiac output increased to the same extent (0.7 L/min) in both groups. Within and between the groups, there were no relevant changes in pulmonary filling pressures. The number of patients not responding adequately to the study medication (mean arterial pressure > 85 mmHg after 30 minutes despite the maximum doses of study medication) was comparable in both groups (9 [U] v 13 [K]). Adverse events attributable to the study medication occurred to a similar degree in both groups. In the patients treated with urapidil, a significantly higher incidence (32.3%) of hypotension (mean arterial pressure < or = 65 mmHg for more than 10 minutes) occurred after 60 minutes of continuous infusion.

CONCLUSIONS

In contrast to ketanserin, urapidil did not increase heart rate. Urapidil was more effective in lowering arterial blood pressure than ketanserin. However, one third of the patients treated with urapidil developed hypotension after 60 minutes of continuous infusion.

Ultrastructure and immunohistochemistry of the coronary chemoreceptor in human and canine hearts

Ultrastructure of the coronary chemoreceptor that causes a hypertensive reflex was studied immunohistochemically in human and canine hearts. Both cytologic and histologic features were similar in human beings and dogs, consisting of chief cells, sustentacular cells, Schwann cells, nerve fibers, blood vessels, and connective tissue. Three or four chief cells were typically surrounded by one Schwann cell, making a glomoid cluster about 20 microns across. Volume fractions of chief cells compared to capillaries were about 1:2 in dog and 1:4 in human chemoreceptors. Abundant osmiophilic dense granules filled the chief cells. Complex junctions between nerve fibers, chief cells, and sustentacular cells or Schwann cells exhibited a characteristic fine structure. Immunohistochemically, serotonin reactivity was observed mainly in the vicinity of junctions between nerve endings and chief cells, but some large granules in chief cells also stained positively. These new morphologic findings provide further support for the probable role of serotonin in the activation of the cardiogenic hypertensive chemoreflex in both human and canine hearts.

Thoracic epidural analgesia in aortocoronary bypass surgery. II: Effects on the endocrine metabolic response

Thoracic epidural analgesia (TEA) may offer haemodynamic benefits for patients with coronary heart disease going through major surgery. This may-in part-be secondary to an effect on the endocrine and metabolic response to surgery. We therefore investigated the effect of TEA on the endocrine metabolic response to aortocoronary bypass surgery (ACBS). Thirty male patients (age < 65 years, ejection fraction > 0.5) were randomized into 3 groups; the HF group receiving a high dose fentanyl (55 micrograms.kg-1) anaesthesia, the HF+TEA group with the same fentanyl dose+TEA with 10 ml bupivacain 5 mg.ml-1, followed by 4 ml every hour, and the LF+TEA group receiving fentanyl 15 micrograms.kg-1 + TEA. Adrenalin, noradrenalin, systemic vascular resistance (SVR), glucose, cortisol, lactate and free fatty acids were followed during the operation and for 20 h postoperatively. A significant increase in adrenalin, noradrenalin and SVR was found in the HF group whereas this increase was blocked in both epidural groups. An increase in glucose and cortisol was noticed in all groups, but the increase was delayed in the epidural groups. Our results suggest that a more effective blockade of the stress response during ACBS is obtained when TEA is added to general anaesthesia than with high dose fentanyl anaesthesia alone.

Effects of cardiac denervation on coronary and systemic circulation

The effects of cardiac denervation on coronary circulation and systemic hemodynamics were examined in patients who underwent coronary artery bypass grafting for a totally occluded left anterior descending coronary artery. The results in 14 patients who had undergone a combination of bypass grafting and intrapericardial denervation (group I) were compared with those in 19 patients who had undergone only bypass grafting (group II). The heart rate was 110 +/- 4.9 beats/min in group I and 104 +/- 3.7 beats/min in group II after denervation. Although the cardiac index was not significantly different between the two groups, the calculated systemic vascular resistance index of group I (1,358 +/- 111 dynes.s.cm-5.m2) was significantly lower (p < 0.02) than that in group II (1,713 +/- 75 dynes.s.cm-5.m2). The end-diastolic coronary resistance was significantly lower (p < 0.05) in group I (0.59 +/- 0.05 mm Hg.mL-1.min-1) than that in group II (1.04 +/- 0.14 mm Hg.mL-1.min-1), and the end-diastolic graft flow/mean graft flow ratio was 1.56 +/- 0.05 in group I and 1.28 +/- 0.04 in group II (p < 0.01). The plasma norepinephrine concentration in group I (223 +/- 52 pg/mL) was significantly low (p < 0.05) compared with that in group II (328 +/- 39 pg/mL) after denervation. Thus, cardiac denervation may have a beneficial effect on systemic hemodynamics and coronary circulation.

Plasma catecholamine concentrations during abdominal aortic aneurysm surgery: the link to perioperative myocardial ischemia

Cardiac disease continues to be the leading cause of morbidity and mortality following peripheral vascular surgical procedures. Although the mechanism of sudden myocardial infarction remains elusive, many possibilities exist. The role of catecholamines is intriguing in view of the evidence that beta-adrenergic blockers reduce cardiac morbidity and mortality in vascular surgical patients. To ascertain whether the plasma catecholamine levels rise significantly during abdominal aortic aneurysm repair, serial determinations of plasma epinephrine and norepinephrine levels were performed in 18 patients. Epinephrine levels rose significantly from preoperative baseline values both during the operation and postoperatively, and norepinephrine levels rose significantly at 24 hours postoperatively. Although only one patient studied developed a myocardial infarction, the finding that patients undergoing aortic surgery uniformly experienced abnormally high serum catecholamine levels supports other evidence that perioperative myocardial ischemic events have a hormonal component.

Comparison of frequency of aggravation of ventricular tachyarrhythmias after implantation of automatic defibrillators using epicardial versus nonthoracotomy lead systems

The time of onset of 4,471 episodes of ventricular tachycardia (VT) or fibrillation (VF) in 40 of 65 patients with an implantable cardioverter-defibrillator (ICD) with endocardial defibrillation electrodes (group 1) and in 53 of 123 with epicardial defibrillation electrodes (group 2) was analyzed to examine whether the incidence of VT/VF immediately after surgery is greater than during further follow up and whether the site of lead placement exerts an influence on the occurrence of these arrhythmias. Actuarial survival rates free of VT/VF were 77, 65, and 54% at 1, 3 and 6 months, respectively, for group 1, and 84, 66 and 52%, respectively, for group 2. The probability of VT/VF was increased only during the first week after surgery; in that week, 12.8% of all patients had VT/VF, without significant differences between groups 1 and 2. Until the end of the first month, this percentage increased to 23%, whereas only 12 to 15% of patients had VT/VF during subsequent months. In 19 patients with third-generation devices capable of terminating tachycardias by overdrive pacing, 326 of 412 VT/VF episodes occurring in the first week after surgery were terminated by antitachycardia pacing, and only 86 had to be terminated by cardioversion or defibrillation. No postoperative exacerbation of inappropriate ICD therapies was observed in any group; 2 to 5% of patients per month received ICD therapies for atrial fibrillation or sinus tachycardia. Patients who received appropriate ICD therapies in the first week after surgery were at high risk of recurrence of VT/VF.(ABSTRACT TRUNCATED AT 250 WORDS)

Serotonin and acute cardiovascular disorders

In this survey the possible role of serotonin in such acute disorders as systemic and pulmonary hypertension following cardiac surgery is discussed. Although platelets are activated during cardiopulmonary bypass, the increase in serotonin plasma levels is limited because the serotonin released is taken up by normal platelets and endothelial cells. This does not imply that serotonin is not involved in the origin of systemic hypertension during and after cardiac surgery, because subthreshold or threshold doses of this amine amplify the vasoconstrictive effect of, for example, epinephrine and norepinephrine, the levels of which are significantly elevated under these circumstances. That serotonin plays a role through its amplifying effect is supported by the finding that ketanserin, a specific S2-serotonergic receptor antagonist with alpha 1-adrenergic receptor blocking properties, effectively lowers arterial blood pressure in patients with systemic postoperative hypertension by combined blockade of these receptors. The compound is also effective in the treatment of pulmonary hypertension after valve replacement, indicating that serotonin plays a role in the origin of this disorder. This idea is supported by the experimental finding that serotonin induces pulmonary hypertension. It is an interesting observation that, unlike such compounds as nitroprusside, ketanserin does not affect intrapulmonary shunting in patients with systemic hypertension and even reduces the intrapulmonary shunt fraction in patients with pulmonary hypertension. These findings indicate that this compound dilates the resistance vessels in well-ventilated, but not in poorly ventilated areas, and may dilate constricted bronchi.(ABSTRACT TRUNCATED AT 250 WORDS)

The influence of rapid potassium administration on hemodynamics and endogenous catecholamine production during extracorporeal circulation

In a prospective randomized double-blind study, the peripheral vascular effects of potassium chloride (KCl) and potassium-magnesium-aspartate (KMA) were compared. Twenty patients undergoing coronary artery bypass graft surgery received either 12 mmol of KCl (n = 10) or 12 mmol of KMA (n = 10) into the oxygenator of the heart-lung machine during extracorporeal circulation (ECC). The most striking difference between these two solutions was vasoconstriction following KCl administration and vasodilation after KMA injection. In the KMA group, decreases of perfusion pressure (MAP) and systemic vascular resistance (SVR), as well as changes in the oxygenator volume (dV), were significant (P less than 0.01) between the first and the fifth minutes. Maximal changes of MAP, from 72 +/- 13 to 59 +/- 12 mmHg (mean +/- SD), and SVR were recorded in the first and second minutes. Oxygenator volume changes reached their maximum (285 +/- 163 mL) in the tenth minute. In the KCl group, maximal increases in MAP, from 70 +/- 16 to 81 +/- 20 mmHg (mean +/- SD), and SVR were found in the fourth minute. Maximal changes in dV (300 +/- 315 mL) were measured in the tenth minute. Plasma epinephrine levels, which were already elevated during ECC, showed further increases in all cases in the KCl group and in most of the cases in the KMA group. The change in plasma epinephrine concentration following KCl injection was significant (P less than 0.01). No characteristic change in plasma norepinephrine was found in either of the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Catecholamine binding and concentrations in acute phase plasma after surgery

The present study was undertaken to decide whether the bound fractions and/or total concentrations of catecholamines were determinative for the variability of biologically active concentrations in human plasma. The binding and concentrations of noradrenaline (NA) and adrenalin (Adr) were determined in acute phase plasma after major hip surgery in five subjects. The bound fractions before surgery were 23.0% and 18.4% for NA and Adr, respectively. The binding of catecholamines increased in the post-operative period. Five days after surgery the binding of NA and Adr was 30.9% and 24.0%, respectively. The surgical trauma induced an acute phase reaction in plasma with a decrease of albumin (HSA) concentrations whereas the concentrations of alpha-1 acid glycoprotein (AAG) increased. The catecholamine concentrations showed a considerable inter- and intraindividual variability. However, the present work shows that the variability of the biologically active catecholamine concentrations is mainly dependent on the total plasma concentrations and not the plasma protein binding.

Hormonal and metabolic changes during hypothermic coronary artery bypass surgery in diabetic and non-diabetic subjects

Hormonal and metabolic responses to hypothermic coronary artery bypass grafting (CABG) were studied in three groups: 8 non-diabetic patients, 8 patients with non-insulin-dependent diabetes mellitus (NIDDM) given a glucose pump priming solution and 8 NIDDM patients given a non-glucose infusion. There were no significant differences in stress hormone responses between NIDDM and non-diabetic patients, with adrenaline concentrations rising 10-fold, noradrenaline 4-fold and cortisol 2 to 3-fold. Glucagon rose significantly during bypass only in the NIDDM patients who did not receive a glucose prime. Comparable marked hyperglycaemia was seen in both glucose primed groups during bypass and exclusion of glucose from the prime in NIDDM patients prevented this major rise. Postoperatively, the rise in insulin in the glucose primed NIDDM patients contrasted with the slower rise in the non-glucose primed NIDDM patients who were also hyperglycaemic by this stage. Perioperative hyperglycaemia in NIDDM patients undergoing CABG can be prevented by using a non-glucose priming solution and by giving insulin infusion, particularly postoperatively.

Esmolol: a titratable short-acting intravenous beta blocker for acute critical care settings

Esmolol (Brevibloc) is an intravenous, short-acting, titratable, cardioselective beta blocker with a very rapid onset and offset of action (t1/2 = 9.2 minutes). Esmolol-induced beta blockade can be maintained as long as infusion is continued. It exhibits neither intrinsic sympathomimetic activity nor significant membrane-stabilizing activity. It is rapidly metabolized by an esterase in the erythrocyte cytosol to an inactive acid metabolite. Its hemodynamic and electrophysiologic effects are similar to those of other beta blockers. Unlike the effects of other beta blockers, however, the effects of esmolol dissipate rapidly to baseline within 30 minutes after its discontinuation. Evidence obtained from clinical studies indicates that esmolol is effective and safe in reducing the ventricular rate in patients with supraventricular tachyarrhythmias, and in reducing the heart rate in patients with acute myocardial infarction and/or unstable angina. Esmolol has also been shown to be effective and safe in attenuating the tachycardia and hypertension seen during the intraoperative period. Data from postoperative patients indicate that esmolol is ideal as sole-agent therapy for the treatment of moderate postoperative hypertension associated with a hyperdynamic state. The short duration of action and titratability of esmolol make it an ideal drug for use in patients in whom the clinical need for beta blockade is limited in duration, and it offers additional safety in patients in whom beta blockade is beneficial; however, it might be precluded because of coexisting contraindications. To date, experience with esmolol in over 1200 patients has been gathered, and the adverse effect profile is basically similar to that reported here.

Comparison of esmolol and nitroprusside for acute post-cardiac surgical hypertension

Because acute systemic hypertension early after cardiac surgery has been linked to catecholamine elevation, an open-label, randomized, crossover study was performed to compare the efficacy of esmolol, a new ultra-short-acting intravenous beta-blocking agent, to nitroprusside, the standard therapy. Controlled drug infusions to maximal dosage (esmolol, 300 micrograms/kg/min, and nitroprusside, 10 micrograms/kg/min) were titrated to achieve at least a 15% reduction in systolic pressure. The blood pressure (BP) endpoint was achieved with esmolol (within 29 +/- 14 minutes) in 18 of 20 patients (90%), compared with 19 of 20 (95%) with nitroprusside infusion (within 21 +/- 15 minutes, difference not significant [NS]). Systolic BP decreased from 170 +/- 13 to 136 +/- 12 mm Hg (mean +/- standard deviation) with esmolol and from 170 +/- 13 to 141 +/- 13 mm Hg with nitroprusside infusion (both p less than 0.05). Diastolic BP was reduced from 71 +/- 12 to 64 +/- 11 mm Hg with esmolol and from 71 +/- 12 to 52 +/- 13 mm Hg with nitroprusside infusion (both p less than 0.05). Esmolol infusion resulted in decreased heart rate, cardiac index and stroke volume index and increased right atrial pressure (all p less than 0.05), whereas nitroprusside infusion resulted in increased heart rate and cardiac index and decreased right atrial pressure, pulmonary arterial wedge pressure and systemic vascular resistance (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma catecholamine changes during cardiopulmonary bypass: a randomised double blind comparison of trimetaphan camsylate and sodium nitroprusside

The effects of trimetaphan camsylate and sodium nitroprusside on the catecholamine response to cardiac surgery were compared in a randomised double blind study of twelve male patients undergoing elective myocardial revascularisation. The solutions were titrated to maintain a mean arterial pressure of 70-85 mm Hg before and after bypass and less than 70 mm Hg during bypass. The rise in plasma adrenaline during cardiopulmonary bypass in the sodium nitroprusside group was significantly greater than that in the trimetaphan camsylate group. There was a smaller rise in plasma noradrenaline in the sodium nitroprusside patients but this was significantly higher than in the patients receiving trimetaphan camsylate. Administration of trimetaphan camsylate provides a simple and effective way to reduce catecholamine release during cardiopulmonary bypass.

Use of esmolol in hypertension after cardiac surgery

Systolic hypertension, which is common soon after cardiac surgery, increases cardiac work and may threaten fresh vascular anastomoses. Because postoperative hypertension is often associated with elevated catecholamines and preoperative use of beta-blocking agents, esmolol, an ultrashort-acting beta-blocking agent, was compared with nitroprusside in a crossover study in this setting. Twelve patients, 18 to 28 hours after cardiac surgery (coronary artery bypass graft in 9, aortic valve replacement in 2 and valved aortic conduit with reimplantation of coronary arteries in 1 patient) received controlled infusions of esmolol (mean dosage 142 +/- 100 micrograms/kg/min, range 50 to 300 micrograms/kg/min) and nitroprusside (mean dose 1.6 +/- 1.3 micrograms/kg/min, range 0.5 to 2.75 micrograms/kg/min). In this open-label study, choice of the first drug was randomized, after which patients were then crossed over to the other study drug. Therapeutic response (greater than or equal to 15% systolic blood pressure reduction) was achieved in 11 of 12 esmolol patients and 12 of 12 nitroprusside patients. Both drugs significantly lowered systolic and diastolic blood pressure, as well as left ventricular stroke work index. While the cardiac index was decreased by esmolol and increased by nitroprusside, neither drug significantly changed stroke volume index. Systemic vascular resistance, unchanged by esmolol, was decreased significantly by nitroprusside. Oxygen saturation and Pao2, unchanged with esmolol, were both significantly reduced with nitroprusside. Thus, for hypertension early after cardiac surgery, esmolol is safe, effective and rapid and, compared with nitroprusside, results in less unwanted decrease in diastolic blood pressure and oxygen saturation, but there is more decrease in heart rate and cardiac index.

Intravenous sotalol for the treatment of atrial fibrillation and flutter after cardiopulmonary bypass. Comparison with disopyramide and digoxin in a randomised trial

The efficacy of sotalol in treating acute atrial fibrillation and flutter after open heart surgery was compared with that of a digoxin/disopyramide combination. Forty adult patients with postoperative atrial arrhythmias were randomised into either group 1 (sotalol 1 mg/kg bolus intravenously plus 0.2 mg/kg intravenously over 12 hours) or group 2 (digoxin 0.75 mg intravenously, then two hours later disopyramide 2 mg/kg intravenous bolus and 0.4 mg/kg/h intravenously for 10 hours). In each group, 17 out of 20 patients reverted to sinus or junctional rhythm within 12 hours. The time to reversion in group 1 was significantly shorter than in group 2. Systolic blood pressure fell by greater than or equal to 20 mm Hg or to less than or equal to 90 mm Hg during drug administration in 17 out of 20 patients in group 1 (sotalol withdrawn in two) and in none out of 20 in group 2. Two patients in group 1 developed transient bradycardia (sotalol withdrawn in one). None of 17 patients in group 1 and two of 17 in group 2 relapsed temporarily into atrial fibrillation during the 12 hours of intravenous treatment. On continued oral treatment, one late relapse occurred in group 1 and five in group 2, and five patients in group 2 had disopyramide withdrawn because of anticholinergic side effects (acute urinary retention in four). Sotalol was as effective as the digoxin/disopyramide combination and acted significantly faster. Sensitivity to beta blockade in these patients may be related to high plasma catecholamine concentrations known to occur after cardiopulmonary bypass.

Esmolol: a new ultrashort-acting beta-adrenergic blocking agent for rapid control of heart rate in postoperative supraventricular tachyarrhythmias

Prompt control of heart rate is important for successful treatment of supraventricular tachyarrhythmias early after open heart surgery when sympathetic tone is high and ventricular response rates may be rapid. Esmolol, a new ultrashort-acting (9 minute half-life) beta-receptor blocking agent, was given by continuous intravenous infusion for up to 24 hours in 24 patients (21 with isolated coronary bypass surgery and 3 with valve replacement) 1 to 7 days after surgery. Atrial fibrillation was present in 9 patients, atrial flutter in 2 and sinus tachycardia in 13. Eleven patients had received intravenous digoxin (average dose 0.6 mg, average serum level 1.19 mg/100 ml) before esmolol infusion without adequate control of the supraventricular tachyarrhythmia. After a 1 minute loading infusion of esmolol (500 micrograms/kg per min), maintenance dose, titrated to heart rate and blood pressure response, varied from 25 to 300 micrograms/kg per min. After esmolol administration, at an average dose of 139 +/- 83 micrograms/kg per min, mean heart rate decreased from 130 +/- 15 to 99 +/- 15 beats/min. Within 5 to 18 minutes after initiation of therapy, all patients had achieved a 15% reduction in heart rate at a maintenance dose of 150 micrograms/kg per min or less. A 20% reduction in heart rate was attained in 19 of the 24 patients, and conversion to sinus rhythm occurred during esmolol infusion in 5 of the 11 patients with atrial flutter or fibrillation. Transient asymptomatic hypotension (less than 90/50 mm Hg) was seen in 13 patients, requiring cessation of esmolol therapy in 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Concepts and techniques of myocardial protection for adult open heart surgery

Discussions of myocardial protection are often limited to the subject of cardioplegia. However, numerous aspects of operative and perioperative care are of comparable importance. This article outlines the broad topic of myocardial protection, provides strategies for its practical implementation, and reports the author's personal results.

Depression of pulmonary metabolic function by cardiopulmonary bypass procedures increases levels of circulating norepinephrine

We measured plasma levels of endogenous norepinephrine radioenzymatically in mixed venous and arterial blood simultaneously sampled from anesthetized dogs before, during, and after 1 to 4 hours of total cardiopulmonary bypass (CPB) or 2 hours of left heart bypass. Prior to bypass, arterial levels of norepinephrine were 0.41 +/- 0.04 ng/ml and pulmonary extraction of norepinephrine was 25 +/- 3% (N = 20). During bypass, norepinephrine levels significantly increased from control to 1.41 +/- 0.15 (1 or 2 hours of CPB; N = 8) and 1.97 +/- 0.30 (3 or 4 hours of CPB; N = 8) or 0.97 +/- 0.29 (2 hours of left heart bypass) ng/ml. Restoration of normal pulmonary blood flow was associated with a rapid and significant decrease in arterial levels of norepinephrine, which, after 1 or 2 hours of CPB or 2 hours of left heart bypass, returned to levels obtained before bypass. However, arterial levels of norepinephrine remained higher than 1 ng/ml in the 3-hour recovery period after prolonged bypass. In these animals, pulmonary extraction of norepinephrine was significantly less than control. These data suggest that the lung's ability to remove norepinephrine is altered by CPB and that the severity of the alterations is directly related to pump time. The impairment in extraction allows higher than normal concentrations of norepinephrine to enter the arterial circulation and may contribute to systemic hypertension after bypass.