Risk factors associated with new onset tachyarrhythmias after cardiac surgery--a retrospective analysis

Using Soluble ST2 to Predict Adverse Postoperative Outcomes in Patients with Impaired Left Ventricular Function Undergoing Coronary Bypass Surgery

Background and Objectives: The aim of this study was to investigate the prognostic value of soluble ST2 (sST2) in predicting postoperative adverse events in patients with impaired left ventricular (LV) function undergoing coronary artery bypass graft (CABG) surgery. Materials and Methods: This study included 80 consecutive patients with stable coronary artery disease (CAD) and impaired LV function (ejection fraction ≤ 45%) undergoing on-pump coronary artery bypass graft surgery. The patients were divided into the “high” or “low” group according to their ST2 levels (≥35 or <35 ng/mL). Results: Postoperative adverse events were more common in patients with high sST2 levels than in patients with low sST2 levels (100% vs 26%, p < 0.0001). Multivariate analysis showed that sST2 level was an independent predictor of the presence of postoperative adverse events (OR: 1.117 (95% CI: 1.016–1.228), p = 0.022). The receiver operating characteristic curve (ROC) analysis of sST2 revealed an area under the curve (AUC) of 0.812 (95% CI: 0.710–0.913, p < 0.001) in predicting postoperative adverse events. An sST2 level of 26.50 ng/ml was identified as the optimal cut-off value, with a sensitivity and specificity of 74.1% and 75.3%, respectively. Conclusion: Higher sST2 levels were associated with adverse outcomes after CABG in patients with impaired LV and stable CAD.

Modified criteria for the systemic inflammatory response syndrome improves their utility following cardiac surgery

BACKGROUND

Debate remains regarding whether the systemic inflammatory response syndrome (SIRS) identifies patients with clinically important inflammation. Defining criteria may be disproportionately sensitive and lack specificity. We investigated the incidence and evolution of SIRS in a homogenous population (following cardiac surgery) over 7 days to establish the relationship between SIRS and outcome, modeling alternative permutations of the criteria to increase their discriminatory power for mortality, length of stay, and organ dysfunction.

METHODS

We conducted a retrospective analysis of prospectively collected data from a cardiothoracic ICU. Consecutive patients requiring ICU admission for the first time after cardiac surgery (N = 2,764) admitted over a 41-month period were studied.

RESULTS

Concurrently, 96.2% of patients met the standard two criterion definition for SIRS within 24 h of ICU admission. Their mortality was 2.78%. By contrast, three or four criteria were more discriminatory of patients with higher mortality (4.21% and 10.2%, respectively). A test dataset suggested that meeting two criteria for at least 6 consecutive h may be the best model. This had a positive and negative predictive value of 7% and 99.5%, respectively, in a validation dataset. It performed well at predicting organ dysfunction and prolonged ICU admission.

CONCLUSIONS

The concept of SIRS remains valid following cardiac surgery. With suitable modification, its specificity can be improved significantly. We propose that meeting two or more defining criteria for 6 h could be used to define better populations with more difficult clinical courses following cardiac surgery. This group may merit a different clinical approach.

Incidence of stroke and acute renal failure in patients of postoperative atrial fibrillation after myocardial revascularization

Introduction

Postoperative atrial fibrillation is the most common arrhythmia in cardiac surgery, its incidence range between 20% and 40%.

Objective

Quantify the occurrence of stroke and acute renal insufficiency after myocardial revascularization surgery in patients who had atrial fibrillation postoperatively.

Methods

Cohort longitudinal bidirectional study, performed at Portuguese Beneficent Hospital (SP), with medical chart survey of patients undergoing myocardial revascularization surgery between June 2009 to July 2010. From a total of 3010 patients were weaned 382 patients that presented atrial fibrillation preoperatively and/or associated surgeries. The study was conducted in accordance with national and international following resolutions: ICH Harmonized Tripartite Guidelines for Good Clinical Practice - 1996; CNS196/96 Resolution, and Declaration of Helsinki.

Results

The 2628 patients included in this study were divided into two groups: Group I, who didn't show postoperative atrial fibrillation, with 2302 (87.6%) patients; and group II, with 326 (12.4%) who developed postoperative atrial fibrillation. The incidence of stroke in patients was 1.1% without postoperative atrial fibrillation vs. 4% with postoperative atrial fibrillation (P<0.001). Postoperative acute renal failure was observed in 12% of patients with postoperative atrial fibrillation and 2.4% in the group without postoperative atrial fibrillation (P<0.001), that is a relation 5 times greater.

Conclusion

In this study there was a high incidence of stroke and acute renal failure in patients with postoperative atrial fibrillation, with rates higher than those reported in the literature.

Untreated preoperative depression is not associated with postoperative arrhythmias in CABG patients

PURPOSE

The mechanism by which depression affects postoperative outcome may involve arrhythmias. The purpose of this study was to evaluate whether untreated depression is associated with an increased incidence of postoperative arrhythmias in patients undergoing coronary artery bypass graft surgery (CABG).

METHODS

One hundred seven patients were assessed for signs of depression with the Prime-MD Patient Health Questionnaire (brief PHQ) one week before surgery and subsequently underwent Holter monitoring for 48-72 hr postoperatively. The incidences of atrial fibrillation (AF); supraventricular tachycardia (SVT); ventricular tachycardia (VT), defined as three or more consecutive beats at a cycle length less than 600 msec; ventricular fibrillation (VF); and average heart rate (HR) were recorded in patients with and without signs of depression.

RESULTS

The incidence of preoperative untreated depression was 27% (29/107). Twenty patients had mild depression (brief PHQ score of 5-9), seven patients had moderate depression (a score of 10-14), and two patients had severe depression (a score of 20). The incidences of postoperative AF, SVT, and non-sustained VT in depressed and non-depressed patients were 37.9% vs 35.9%, respectively (P = 0.50), 34.4% vs 52.5%, respectively (P = 0.07), and 17.2% vs 37.1%, respectively (P = 0.04). The average (SD) postoperative HR was similar in both groups [95 (12) beats·min(-1) in depressed patients and 92 (10) beats·min(-1) in non-depressed patients, (P = 0.25)]. Multivariate regression analysis showed that older age, but not depression, was a risk factor for postoperative arrhythmia.

CONCLUSIONS

Preoperative untreated depression is not related to postoperative arrhythmia in the early postoperative period in patients undergoing elective CABG. This trial was registered at clinicaltrials.gov (number: NCT00622024).

Role of ion channels in sepsis-induced atrial tachyarrhythmias in guinea pigs

BACKGROUND AND PURPOSE

Supraventricular tachyarrhythmias, including atrial fibrillation, are occasionally observed in patients suffering from sepsis. Modulation of cardiac ion channel function and expression by sepsis may have a role in the genesis of tachyarrhythmias.

EXPERIMENTAL APPROACH

Sepsis was induced by LPS (i.p.; 300 µg·kg(-1) ) in guinea pigs. Membrane potentials and ionic currents were measured in atrial myocytes isolated from guinea pigs 10 h after LPS, using whole cell patch-clamp methods.

KEY RESULTS

In atrial cells from LPS-treated animals, action potential duration (APD) was significantly shortened. It was associated with a reduced L-type Ca(2+) current and an increased delayed rectifier K(+) current. These electrophysiological changes were eliminated when N(G) -nitro-l-arginine methyl ester (l-NAME) or S-ethylisothiourea was given together with LPS. In atrial tissues from LPS-treated animals, Ca(2+) channel subunits (Ca(v) 1.2 and Ca(v) 1.3) decreased and delayed rectifier K(+) channel subunits (K(v) 11.1 and K(v) 7.1) increased. However, L-NAME treatment did not substantially reverse such changes in atrial expression in LPS-treated animals, with the exception that K(v) 11.1 subunits returned to control levels. After LPS injection, inducible NOS in atrial tissues was up-regulated, and atrial NO production clearly increased.

CONCLUSIONS AND IMPLICATIONS

In atrial myocytes from guinea pigs with sepsis, APD was significantly shortened. This may reflect nitration of the ion channels which would alter channel functions, rather than changes in atrial expression of the channels. Shortening of APD could serve as one of the mechanisms underlying atrial tachyarrhythmia in sepsis.

Adverse cardiac events during catecholamine vasopressor therapy: a prospective observational study

PURPOSE

To determine the incidence of and risk factors for adverse cardiac events during catecholamine vasopressor therapy in surgical intensive care unit patients with cardiovascular failure.

METHODS

The occurrence of any of seven predefined adverse cardiac events (prolonged elevated heart rate, tachyarrhythmia, myocardial cell damage, acute cardiac arrest or death, pulmonary hypertension-induced right heart dysfunction, reduction of systemic blood flow) was prospectively recorded during catecholamine vasopressor therapy lasting at least 12 h.

RESULTS

Fifty-four of 112 study patients developed a total of 114 adverse cardiac events, an incidence of 48.2 % (95 % CI, 38.8-57.6 %). New-onset tachyarrhythmia (49.1 %), prolonged elevated heart rate (23.7 %), and myocardial cell damage (17.5 %) occurred most frequently. Aside from chronic liver diseases, factors independently associated with the occurrence of adverse cardiac events included need for renal replacement therapy, disease severity (assessed by the Simplified Acute Physiology Score II), number of catecholamine vasopressors (OR, 1.73; 95 % CI, 1.08-2.77; p = 0.02) and duration of catecholamine vasopressor therapy (OR, 1.01; 95 % CI, 1-1.01; p = 0.002). Patients developing adverse cardiac events were on catecholamine vasopressors (p < 0.001) and mechanical ventilation (p < 0.001) for longer and had longer intensive care unit stays (p < 0.001) and greater mortality (25.9 vs. 1.7 %; p < 0.001) than patients who did not.

CONCLUSIONS

Adverse cardiac events occurred in 48.2 % of surgical intensive care unit patients with cardiovascular failure and were related to morbidity and mortality. The extent and duration of catecholamine vasopressor therapy were independently associated with and may contribute to the pathogenesis of adverse cardiac events.

Adverse cardiac events during catecholamine vasopressor therapy: a prospective observational study

PURPOSE

To determine the incidence of and risk factors for adverse cardiac events during catecholamine vasopressor therapy in surgical intensive care unit patients with cardiovascular failure.

METHODS

The occurrence of any of seven predefined adverse cardiac events (prolonged elevated heart rate, tachyarrhythmia, myocardial cell damage, acute cardiac arrest or death, pulmonary hypertension-induced right heart dysfunction, reduction of systemic blood flow) was prospectively recorded during catecholamine vasopressor therapy lasting at least 12 h.

RESULTS

Fifty-four of 112 study patients developed a total of 114 adverse cardiac events, an incidence of 48.2 % (95 % CI, 38.8-57.6 %). New-onset tachyarrhythmia (49.1 %), prolonged elevated heart rate (23.7 %), and myocardial cell damage (17.5 %) occurred most frequently. Aside from chronic liver diseases, factors independently associated with the occurrence of adverse cardiac events included need for renal replacement therapy, disease severity (assessed by the Simplified Acute Physiology Score II), number of catecholamine vasopressors (OR, 1.73; 95 % CI, 1.08-2.77; p = 0.02) and duration of catecholamine vasopressor therapy (OR, 1.01; 95 % CI, 1-1.01; p = 0.002). Patients developing adverse cardiac events were on catecholamine vasopressors (p < 0.001) and mechanical ventilation (p < 0.001) for longer and had longer intensive care unit stays (p < 0.001) and greater mortality (25.9 vs. 1.7 %; p < 0.001) than patients who did not.

CONCLUSIONS

Adverse cardiac events occurred in 48.2 % of surgical intensive care unit patients with cardiovascular failure and were related to morbidity and mortality. The extent and duration of catecholamine vasopressor therapy were independently associated with and may contribute to the pathogenesis of adverse cardiac events.

Prognostic factors of atrial fibrillation following elective coronary artery bypass grafting: the impact of quantified intraoperative myocardial ischemia

Background

Atrial fibrillation (AF) occurs in 28-33% of the patients undergoing coronary artery revascularization (CABG). This study focuses on both pre- and peri-operative factors that may affect the occurrence of AF. The aim is to identify those patients at higher risk to develop AF after CABG.

Patients and methods

Two patient cohorts undergoing CABG were retrospectively studied. The first group (group A) consisted of 157 patients presenting AF after elective CABG. The second group (group B) consisted of 191 patients without AF postoperatively.

Results

Preoperative factors presenting significant correlation with the incidence of post-operative AF included: 1) age > 65 years (p = 0.029), 2) history of AF (p = 0.022), 3) chronic obstructive pulmonary disease (p = 0.008), 4) left ventricular dysfunction with ejection fraction < 40% (p = 0.015) and 5) proximal lesion of the right coronary artery (p = 0.023). The intraoperative factors that appeared to have significant correlation with the occurrence of postoperative AF were: 1) CPB-time > 120 minutes (p = 0.011), 2) myocardial ischemia index < 0.27 ml.m²/Kg.min (p = 0.011), 3) total positive fluid-balance during ICU-stay (p < 0.001), 4) FiO₂/PO₂ > 0, 4 after extubation and during the ICU-stay (p = 0.021), 5) inotropic support with doses 15-30 μg/Kg/min (p = 0.016), 6) long ICU-stay recovery for any reason (p < 0.001) and perioperative myocardial infarction (p < 0.001).

Conclusions

Our results suggest that the incidence of post-CABG atrial fibrillation can be predicted by specific preoperative and intraoperative measures. The intraoperative myocardial ischemia can be sufficiently quantified by the myocardial ischemia index. For those patients at risk we would suggest an early postoperative precautionary anti-arrhythmic treatment.

Sympathetic overstimulation during critical illness: adverse effects of adrenergic stress

The term ''adrenergic'' originates from ''adrenaline'' and describes hormones or drugs whose effects are similar to those of epinephrine. Adrenergic stress is mediated by stimulation of adrenergic receptors and activation of post-receptor pathways. Critical illness is a potent stimulus of the sympathetic nervous system. It is undisputable that the adrenergic-driven ''fight-flight response'' is a physiologically meaningful reaction allowing humans to survive during evolution. However, in critical illness an overshooting stimulation of the sympathetic nervous system may well exceed in time and scope its beneficial effects. Comparable to the overwhelming immune response during sepsis, adrenergic stress in critical illness may get out of control and cause adverse effects. Several organ systems may be affected. The heart seems to be most susceptible to sympathetic overstimulation. Detrimental effects include impaired diastolic function, tachycardia and tachyarrhythmia, myocardial ischemia, stunning, apoptosis and necrosis. Adverse catecholamine effects have been observed in other organs such as the lungs (pulmonary edema, elevated pulmonary arterial pressures), the coagulation (hypercoagulability, thrombus formation), gastrointestinal (hypoperfusion, inhibition of peristalsis), endocrinologic (decreased prolactin, thyroid and growth hormone secretion) and immune systems (immunomodulation, stimulation of bacterial growth), and metabolism (increase in cell energy expenditure, hyperglycemia, catabolism, lipolysis, hyperlactatemia, electrolyte changes), bone marrow (anemia), and skeletal muscles (apoptosis). Potential therapeutic options to reduce excessive adrenergic stress comprise temperature and heart rate control, adequate use of sedative/analgesic drugs, and aiming for reasonable cardiovascular targets, adequate fluid therapy, use of levosimendan, hydrocortisone or supplementary arginine vasopressin.

lipopolysaccharide induces atrial arrhythmogenesis via down-regulation of L-type Ca2+ channel genes in rats

Septic shock has been reported as an independent risk factor for atrial fibrillation (AF), however, the mechanism remains unknown. We investigated whether lipopolysaccharide (LPS) could alter cardiac ion channel gene expression, thereby leading to atrial arrhythmogenesis. LPS (2.5 mg/kg) was injected intraperitoneally into 10 week old Sprague-Dawley rats (n = 5). Hemodynamic data were obtained and the atrial appendages were removed after LPS injection (0, 3, 6, 12, and 24 hours) for an RNase protection assay for alpha1C, beta2, alpha1G, and SCN5A. An electrophysiological study in isolated perfused hearts was performed before and 12 hours after the LPS injection. Heart rate and body temperature were significantly increased (P < 0.05) and mean blood pressure was slightly decreased (P < 0.1) at 12 hours after LPS injection. The mRNA levels of the L-type calcium channel gene (beta2 and alpha1C) were significantly decreased at 6 and 12 hours after LPS injection. Atrial ERP became significantly shortened and the number of repetitive atrial responses induced by an extrastimulus were significantly increased after LPS injection. LPS induced the down-regulation of L-type calcium channel gene expression and ERP shortening, which might be a mechanism underlying sepsis-induced AF.

Current Status of Off-Pump Coronary Artery Bypass Surgery

The expanding indications for angioplasty coupled with the successful short and mid-term results of randomized controlled trials of drug-eluting stents have already had an unquestionable impact on the practice of coronary revascularization operations. However, coronary artery bypass grafting remains a major mode of therapy for coronary artery disease. It is likely that surgery will continue to be preferred for more complex subsets and that surgeons will have to continue to maintain good results in patients with more complex problems. Concerns regarding morbidity associated with conventional surgical myocardial revascularization on cardiopulmonary bypass have led to a resurgence of interest in off-pump bypass surgery during the last decade, with the expectation that it would be safer if cardiopulmonary bypass could be avoided. This review summarizes the impact of off-pump bypass surgery in reducing the morbidity and mortality associated with conventional coronary artery bypass on cardiopulmonary bypass by evaluating the current best-available evidence from randomized controlled trials and meta-analyses comparing off-pump surgery with conventional bypass grafting.

Supraventricular arrhythmias in intensive care unit patients: short and long-term consequences

BACKGROUND

Supraventricular arrhythmias (SVA), including atrial fibrillation and flutter, are common in surgical and nonsurgical intensive care unit (ICU) patients. There is increased mortality among surgical ICU patients who develop new-onset atrial arrhythmias after noncardiac, non-thoracic surgery. We sought to determine the preadmission and intra-ICU factors associated with the development of new-onset SVA and mortality in these patients.

METHODS

Consecutive patients (n = 611) admitted to a general ICU of a tertiary care hospital were prospectively followed until hospital discharge for evidence of SVA, potential etiologies of these arrhythmias, and consequences of the arrhythmias. Excluded were patients who sustained recent cardiac/thoracic surgery or trauma to the thorax. Long-term survival rates (48 mo from the date of hospitalization) were also determined.

RESULTS

Fifty-two (9%) patients developed new-onset SVA and 75 (12%) had prehospital admission histories of SVA. Eighty-seven (18%) of those without SVA died while hospitalized, while 29 (56%) and 23 (31%) of those with new-onset and histories of SVA, respectively, died while hospitalized. ICU mortality in all groups was associated with sepsis, acute renal failure, myocardial ischemia, and high APACHE II scores. The APACHE II scores were higher (23 +/- 8 [sd]) in new-onset SVA than in the group without SVA (16 +/- 8, P < 0.05). Within a year of hospital admission 65% in the new-onset, 50% in the SVA history, and 20% in the no-SVA groups died.

CONCLUSIONS

New-onset SVA occur frequently in ICU patients and are markers of extremely high in-hospital and 1-yr mortality.

Vasopressin during cardiopulmonary resuscitation and different shock states: a review of the literature

Vasopressin administration may be a promising therapy in the management of various shock states. In laboratory models of cardiac arrest, vasopressin improved vital organ blood flow, cerebral oxygen delivery, the rate of return of spontaneous circulation, and neurological recovery compared with epinephrine (adrenaline). In a study of 1219 adult patients with cardiac arrest, the effects of vasopressin were similar to those of epinephrine in the management of ventricular fibrillation and pulseless electrical activity; however, vasopressin was superior to epinephrine in patients with asystole. Furthermore, vasopressin followed by epinephrine resulted in significantly higher rates of survival to hospital admission and hospital discharge. The current cardiopulmonary resuscitation guidelines recommend intravenous vasopressin 40 IU or epinephrine 1mg in adult patients refractory to electrical countershock. Several investigations have demonstrated that vasopressin can successfully stabilize hemodynamic variables in advanced vasodilatory shock. Use of vasopressin in vasodilatory shock should be guided by strict hemodynamic indications, such as hypotension despite norepinephrine (noradrenaline) dosages >0.5 mug/kg/min. Vasopressin must never be used as the sole vasopressor agent. In our institutional routine, a fixed vasopressin dosage of 0.067 IU/min (i.e. 100 IU/50 mL at 2 mL/h) is administered and mean arterial pressure is regulated by adjusting norepinephrine infusion. When norepinephrine dosages decrease to 0.2 microg/kg/min, vasopressin is withdrawn in small steps according to the response in mean arterial pressure. Vasopressin also improved short- and long-term survival in various porcine models of uncontrolled hemorrhagic shock. In the clinical setting, we observed positive effects of vasopressin in some patients with life-threatening hemorrhagic shock, which had no longer responded to adrenergic catecholamines and fluid resuscitation. Clinical employment of vasopressin during hemorrhagic shock is experimental at this point in time.

Atrial fibrillation in trauma patients requiring intensive care

OBJECTIVES

To evaluate the incidence and risk factors of atrial fibrillation (AF) in trauma patients.

DESIGN AND SETTING

Prospective observational study in a surgical intensive care unit (ICU).

PATIENTS

All trauma patients admitted in the surgical ICU except those who had AF at admission.

MEASUREMENTS AND RESULTS

AF occurred in 16/293 patients (5.5%). AF patients were older, had a higher number of regions traumatized, and received more fluid therapy, transfusion products, and catecholamines. They more frequently experienced systemic inflammatory response syndrome, sepsis, shock, and acute renal failure and had higher scores of severity (Simplified Acute Physiology Score, SAPS II; Injury Severity Score). ICU length of stay and resources use were also increased. ICU and hospital mortality rates were twice higher in AF patients whereas standardized mortality ratio (observed/expected mortality by SAPS II) was similar in the two groups. We found five independent risk factors of developing AF: catecholamine use (OR = 5.7, 95% CI 1.7-19.1), SAPS II of 30 or higher (OR = 11.6, 95% CI 1.3-103.0), three or more regions traumatized (OR = 6.2, 95% CI 1.8-21.4), age 40 years or higher (OR = 6.3, CI 1.4-28.7), and systemic inflammatory response syndrome (OR = 4.4, 95% CI 1.2-16.1).

CONCLUSIONS

In addition to age and catecholamine use, inflammation and severity of injury may be involved in the development of AF in trauma patients. Our results suggest that AF could rather be a marker of a higher severity of illness without major effect on mortality.

AHA scientific statement: practice standards for electrocardiographic monitoring in hospital settings: an American Heart Association Scientific Statement from the Councils on Cardiovascular Nursing, Clinical Cardiology, and Cardiovascular Disease in the Young: endorsed by the International Society of Computerized electrocardiology and the American Association of Critical-Care Nurses

The goals of electrocardiographic (ECG) monitoring in hospital settings have expanded from simple heart rate and basic rhythm determination to the diagnosis of complex arrhythmias, myocardial ischemia, and prolonged QT interval. Whereas Computerized arrhythmia analysis is automatic in cardiac monitoring systems, computerized ST-segment ischemia analysis is available only in newer-generation monitors, and computerized QT-interval monitoring is currently unavailable. Even in hospitals with ST-monitoring capability, ischemia monitoring is vastly underutilized by healthcare professionals. Moreover, because no computerized analysis is available for QT monitoring, healthcare professionals must determine when it is appropriate to manually measure QT intervals (eg, when a patient is started on a potentially proarrhythmic drug). The purpose of the present review is to provide "best practices" for hospital ECG monitoring. Randomized clinical trials in this area are almost nonexistent; therefore, expert opinions are based upon clinical experience and related research in the field of electrocardiography. This consensus document encompasses all areas of hospital cardiac monitoring in both children and adults. The emphasis is on information clinicians need to know to monitor patients safely and effectively. Recommendations are made with regard to indications, time frames, and strategies to improve the diagnostic accuracy of cardiac arrhythmia, ischemia, and QT-interval monitoring. Currently available ECG lead systems are described, and recommendations related to staffing, training, and methods to improve quality are provided.

Supraventricular arrhythmias: an electrophysiology primer

Supraventricular arrhythmias are the most wide-spread group of arrhythmias and affect all age groups. Atrial fibrillation is the most common arrhythmic disorder and is even more prevalent among the elderly. Due to their prevalence, it is imperative for the clinician to be informed about these arrhythmias and treatment considerations. This paper presents a basic review of the incidence, pathophysiology, diagnosis, and treatment of supraventricular arrhythmias, along with gender differences, and discusses important implications for the health care provider. A summary of common electrocardiogram findings in supraventricular arrhythmias is presented along with a brief overview of pharmacologic agents.

Practice Standards for Electrocardiographic Monitoring in Hospital Settings

The goals of electrocardiographic (ECG) monitoring in hospital settings have expanded from simple heart rate and basic rhythm determination to the diagnosis of complex arrhythmias, myocardial ischemia, and prolonged QT interval. Whereas computerized arrhythmia analysis is automatic in cardiac monitoring systems, computerized ST-segment ischemia analysis is available only in newer-generation monitors, and computerized QT-interval monitoring is currently unavailable. Even in hospitals with ST-monitoring capability, ischemia monitoring is vastly underutilized by healthcare professionals. Moreover, because no computerized analysis is available for QT monitoring, healthcare professionals must determine when it is appropriate to manually measure QT intervals (eg, when a patient is started on a potentially proarrhythmic drug). The purpose of the present review is to provide ‘best practices’ for hospital ECG monitoring. Randomized clinical trials in this area are almost nonexistent; therefore, expert opinions are based upon clinical experience and related research in the field of electrocardiography. This consensus document encompasses all areas of hospital cardiac monitoring in both children and adults. The emphasis is on information clinicians need to know to monitor patients safely and effectively. Recommendations are made with regard to indications, timeframes, and strategies to improve the diagnostic accuracy of cardiac arrhythmia, ischemia, and QT-interval monitoring. Currently available ECG lead systems are described, and recommendations related to staffing, training, and methods to improve quality are provided.

High-dosage continuous amiodarone therapy to treat new-onset supraventricular tachyarrhythmias in surgical intensive care patients: an observational study

BACKGROUND

New-onset supraventricular tachyarrhythmias (SVTA) are a complication contributing significantly to morbidity and mortality in surgical intensive care unit (SICU) patients. Although only few data on efficiency can be found in the literature, class III antiarrhythmics have become popular in the treatment of SVTA in critically ill patients.

SETTING

12-bed general and surgical ICU in a university teaching hospital.

DESIGN

Observational, retrospective study.

PATIENTS

131 SICU patients with SVTA (narrow-complex non-sinus tachyarrhythmias with heart rates > or = 100 bpm).

INTERVENTION

High-dosage amiodarone infusion according to an institutional protocol.

MEASUREMENTS

Hemodynamic data, acid-base status, and single organ functions were obtained in all patients before amiodarone infusion and at 12, 24, and 48 hours afterwards. Patients were divided into responders and nonresponders. Amiodarone infusion (mean dosage 24 h: 1625+/-528 mg; 48 h: 2708+/-895 mg) restored sinus rhythm in 54% of study patients within 12 h, in 64% within 24 h, and in 75% within 48 h. Heart rate, central venous pressure, and milrinone requirements significantly decreased in all patients; this was accompanied by a significant increase in stroke-volume index and mean arterial pressure. Serum concentrations of creatinine and bilirubin increased in all patients.

CONCLUSION

High-dosage continuous amiodarone infusion during a period of 48 hours resulted in restoration of SR in 75% of SICU patients with new-onset SVTA and moderate to severe multiple-organ dysfunction syndrome. A significant improvement in cardiocirculatory function was more pronounced in responders but could be demonstrated irrespective of restoration of sinus rhythm in all patients. Apart from a possibly amiodarone-mediated increase in concentrations of creatinine and bilirubin, no major drug-related adverse effects occurred during the observation period.

Postbypass arrhythmias: pathophysiology, prevention, and therapy

PURPOSE OF REVIEW

To review the medical literature on new-onset arrhythmias after cardiac bypass surgery in adults, focusing on the most recent advances on this topic.

RECENT FINDINGS

Main attention is focused on possible predictors and prevention of postoperative atrial fibrillation, because this arrhythmia is the most common type encountered with cardiac surgery and is associated with increased morbidity and mortality and longer, more expensive hospital stays. Therapeutic management of atrial fibrillation favors class III antiarrhythmic agents like amiodarone and sotalol. Direct-current cardioversion proved to be an ineffective method for treatment of supraventricular tachyarrhythmias. In patients with persistent atrioventricular block or sinus node dysfunction after cardiac valve surgery, a risk score to predict the need for permanent pacing after cardiac valve surgery was developed. This scoring system may be useful for pre- and perioperative management of patients undergoing cardiac valve surgery.

SUMMARY

Recent studies demonstrate a continued effort to improve our knowledge about postbypass arrhythmias. New insights in the pathophysiology of postoperative cardiac arrhythmias and advances in prevention and therapy are rapid and results are heterogeneous, so it is difficult for the clinician to keep abreast with these new findings.

Incidence and risk factors of atrial fibrillation in a surgical intensive care unit*

OBJECTIVE

To evaluate the incidence and risks factors of atrial fibrillation (AF).

DESIGN

Prospective, observational study.

SETTING

A surgical intensive care unit of a university hospital.

PATIENTS

All patients with new onset of AF admitted in the surgical intensive care unit during a 6-month period.

INTERVENTIONS

None.

MEASUREMENT AND MAIN RESULTS

Of the 460 patients included in the study, AF developed in 24 patients (5.3%). According to univariate analysis, age, preexisting cardiovascular disease, and previous treatment by calcium-channel blockers were significant predictors of AF. Patients with AF received significantly more fluids and catecholamines and experienced more sepsis, shock, and acute renal failure. Severity (Simplified Acute Physiologic Score II), intensive care unit workload (OMEGA), intensive care unit and hospital length of stay, and mortality were significantly increased in patients who developed AF. Multivariate analysis identified five independent predictors of AF: advanced age, blunt thoracic trauma, shock, pulmonary artery catheter, and previous treatment by calcium-channel blockers.

CONCLUSIONS

In surgical intensive care unit patients, the incidence of AF is greater than in the general population but less than in the cardiac surgery unit. The onset of AF reflects the severity of the disease. Five independent risk factors of AF were identified in surgical intensive care unit patients. The withdrawal of a calcium-channel inhibitor was also an independent risk factor of AF, and the weaning of this treatment must be carefully evaluated. Blunt thoracic trauma increases the chances of developing AF, as does the presence of shock, especially septic shock.

Incidence, Timing, Symptoms, and Risk Factors for Atrial Fibrillation After Cardiac Surgery

• Background Atrial fibrillation is the most common complication after cardiac surgery and a major cause of morbidity and increased cost of care.

• Objectives To examine the incidence, timing, symptoms, and risk factors for atrial fibrillation after cardiac surgery.

• Methods A total of 302 patients were continuously monitored for atrial fibrillation with standard hardwire and telemetry devices during hospitalization after coronary artery bypass graft and/or valve surgery and with wearable cardiac event recorders for 2 weeks after discharge from the hospital. After discharge, patients recorded and transmitted their rhythm by telephone daily and whenever they had symptoms suggestive of atrial fibrillation.

• Results Of the 302 patients, 127 (42%) had atrial fibrillation; 41 had it after discharge, and for 10 it was their first episode. The first episode occurred at a mean of 2.9 days after surgery (SD, 3.1; range, day of surgery to 21 days after surgery). Although palpitations was the most common symptom (17%), most episodes of atrial fibrillation (69%) were not associated with symptoms. Independent predictors of atrial fibrillation were age 65 years or greater, history of intermittent atrial fibrillation, atrial pacing, male sex, white race, and not having hyperlipidemia. Independent predictors of atrial fibrillation after discharge from the hospital were having atrial fibrillation while hospitalized, valve surgery, and pulmonary hypertension.

• Conclusions Atrial fibrillation is common after cardiac surgery and often occurs after discharge from the hospital and without accompanying symptoms. Outpatient monitoring may be warranted in patients with characteristics that place them at increased risk for atrial fibrillation.

Arginine vasopressin in advanced vasodilatory shock: a prospective, randomized, controlled study

BACKGROUND

Vasodilatory shock is a potentially lethal complication of severe disease in critically ill patients. Currently, catecholamines are the most widely used vasopressor agents to support blood pressure, but loss of catecholamine pressor effects is a well-known clinical dilemma. Arginine vasopressin (AVP) has recently been shown to be a potent vasopressor agent to stabilize cardiocirculatory function even in patients with catecholamine-resistant vasodilatory shock.

METHODS AND RESULTS

Forty-eight patients with catecholamine-resistant vasodilatory shock were prospectively randomized to receive a combined infusion of AVP and norepinephrine (NE) or NE infusion alone. In AVP patients, AVP was infused at a constant rate of 4 U/h. Hemodynamic, acid/base, single-organ, and tonometrically derived gastric variables were reported before the study and 1, 12, 24, and 48 hours after study entry. For statistical analysis, a mixed-effects model was used. AVP patients had significantly lower heart rate, NE requirements, and incidence of new-onset tachyarrhythmias than NE patients. Mean arterial pressure, cardiac index, stroke volume index, and left ventricular stroke work index were significantly higher in AVP patients. NE patients developed significantly more new-onset tachyarrhythmias than AVP patients (54.3% versus 8.3%). Gastrointestinal perfusion as assessed by gastric tonometry was better preserved in AVP-treated patients. Total bilirubin concentrations were significantly higher in AVP patients.

CONCLUSIONS

The combined infusion of AVP and NE proved to be superior to infusion of NE alone in the treatment of cardiocirculatory failure in catecholamine-resistant vasodilatory shock.

Management of vasodilatory shock: defining the role of arginine vasopressin

The rationale for an arginine vasopressin (argipressin) infusion was put forward after it was discovered that patients in shock states might have an endogenous arginine vasopressin deficiency. Subsequently, several investigations impressively demonstrated that arginine vasopressin can successfully stabilise haemodynamics even in advanced vasodilatory shock. We report on physiological and pharmacological aspects of arginine vasopressin, and summarise current clinical knowledge on employing a continuous arginine vasopressin infusion in critically ill patients with catecholamine-resistant vasodilatory shock of different aetiologies. In view of presented experimental evidence and current clinical experience, a continuous arginine vasopressin infusion of approximately 2 to approximately 6 IU/h can be considered as a supplemental strategy to vasopressor catecholamines in order to preserve cardiocirculatory homeostasis in patients with advanced vasodilatory shock. Because data on adverse effects are still limited, arginine vasopressin should be reserved for patients in whom adequate haemodynamic stabilisation cannot be achieved with conventional vasopressor therapy or who have obvious adverse effects of catecholamines that result in further significant haemodynamic deterioration. For the same reasons, arginine vasopressin should not be used as a single, alternative vasopressor agent instead of catecholamine vasopressors. Future prospective studies will be necessary to define the exact role of arginine vasopressin in the therapy of vasodilatory shock.

Effectiveness of direct-current cardioversion for treatment of supraventricular tachyarrhythmias, in particular atrial fibrillation, in surgical intensive care patients

OBJECTIVE

To evaluate primary success rate and effectiveness of direct-current cardioversion in postoperative critically ill patients with new-onset supraventricular tachyarrhythmias.

DESIGN

Prospective intervention study.

SETTING

Twelve-bed surgical intensive care unit in a university teaching hospital.

PATIENTS

Thirty-seven consecutive, adult surgical intensive care unit patients with new-onset supraventricular tachyarrhythmias without previous history of tachyarrhythmias.

INTERVENTIONS

Direct-current cardioversion using a monophasic, damped sinus-wave defibrillator. Energy levels used were 50, 100, 200, and 300 J for regular supraventricular tachyarrhythmias (n = 6) and 100, 200, and 360 J for irregular supraventricular tachyarrhythmias (n = 31).

MEASUREMENTS AND MAIN RESULTS

None of the patients was hypoxic, hypokalemic, or hypomagnesemic at onset of supraventricular tachyarrhythmia. Direct-current cardioversion restored sinus rhythm in 13 of 37 patients (35% primary responders). Most patients responded to the first or second direct-current cardioversion shock. Only one of 25 patients requiring more than two direct-current cardioversion shocks converted into sinus rhythm. Primary responders were significantly younger and demonstrated significant differences in arterial Po2 values at onset of supraventricular tachyarrhythmias compared with nonresponders. At 24 and 48 hrs, only six (16%) and five (13.5%) patients remained in sinus rhythm, respectively.

CONCLUSIONS

In contrast to recent literature, direct-current cardioversion proved to be an ineffective method for treatment of new-onset supraventricular tachyarrhythmias and, in particular, atrial fibrillation with a rapid ventricular response in surgical intensive care unit patients.

Successful use of iv diltiazem to control perioperative refractory complex atrial tachyarrhythmias in a patient with pneumoconiosis

PURPOSE

To present a patient with pneumoconiosis who developed a complex, life-threatening atrial tachyarrhythmia during anesthesia. Intravenous diltiazem was effective in controlling the ventricular rate and hemodynamics after failure of other antiarrhythmic drugs and direct current cardioversion.

CLINICAL FEATURES

A 79-yr-old man with pneumoconiosis complicated by cor pulmonale suffered from gout-related cellulitis of the left lower limb. Debridement of the left gangrenous big toe was carried out under general anesthesia. During anesthesia, a wide-QRS tachycardia occurred suddenly and a complex atrial tachyarrhythmia was later diagnosed. Hemodynamics deteriorated despite aggressive treatment with lidocaine, verapamil, direct current cardioversion, magnesium, digoxin and amiodarone. Correction of the underlying respiratory acidosis was not sufficient to control the rapid ventricular response. Eventually, iv diltiazem adequately controlled the rapid ventricular rate and quickly improved the deteriorating hemodynamics.

CONCLUSION

Life-threatening complex atrial tachyarrhythmias may occur in patients with chronic lung diseases perioperatively. Intravenous diltiazem was effective in the management of complex atrial tachyarrhythmia in a patient with underlying cor pulmonale.

Clinical significance of early recurrences of atrial fibrillation after pulmonary vein isolation

OBJECTIVES

The purposes of this study were to describe the prevalence of early recurrences of atrial fibrillation (ERAF) that occur within two weeks after pulmonary vein (PV) isolation, and to determine whether ERAF is predictive of long-term outcome after PV isolation.

BACKGROUND

Atrial fibrillation (AF) sometimes recurs within days after PV isolation and may prompt an early repeat intervention.

METHODS

Segmental PV isolation was performed using radiofrequency energy in 110 consecutive patients (mean age 53 +/- 11 years) with paroxysmal (93 patients) or persistent (17 patients) AF. Three to four PVs were targeted for isolation in all patients. Pulmonary vein isolation was complete in 338 of the 358 PVs that were targeted (94%).

RESULTS

Early recurrences of AF occurred in 39 of 110 patients (35%) at a mean of 3.7 +/- 3.5 days after the procedure. The prevalence of ERAF was similar in patients with paroxysmal and persistent AF (33% and 47%, respectively, p = 0.4). Beyond the first two weeks, at 208 +/- 125 days of follow-up, 60 of the 71 patients without ERAF (85%) and 12 of the 39 patients with ERAF (31%) were free of recurrent AF in the absence of antiarrhythmic drug therapy (p < 0.001).

CONCLUSIONS

Early recurrences of AF occur in approximately 35% of patients within two weeks after isolation of three to four PVs, and are associated with a lower long-term success rate than in patients without ERAF. However, approximately 30% of patients with ERAF have no further symptomatic AF during long-term follow-up. Therefore, temporary antiarrhythmic drug therapy may be more appropriate than early repeat ablation in patients with ERAF.