Ventricular tachycardia and in-hospital mortality in the intensive care unit

Background

Continuous electrocardiographic (ECG) monitoring is used to identify ventricular tachycardia (VT), but false alarms occur frequently.

Objective

The purpose of this study was to assess the rate of 30-day in-hospital mortality associated with VT alerts generated from bedside ECG monitors to those from a new algorithm among intensive care unit (ICU) patients.

Methods

We conducted a retrospective cohort study in consecutive adult ICU patients at an urban academic medical center and compared current bedside monitor VT alerts, VT alerts from a new-unannotated algorithm, and true-annotated VT. We used survival analysis to explore the association between VT alerts and mortality.

Results

We included 5679 ICU admissions (mean age 58 ± 17 years; 48% women), 503 (8.9%) experienced 30-day in-hospital mortality. A total of 30.1% had at least 1 current bedside monitor VT alert, 14.3% had a new-unannotated algorithm VT alert, and 11.6% had true-annotated VT. Bedside monitor VT alert was not associated with increased rate of 30-day mortality (adjusted hazard ratio [aHR] 1.06; 95% confidence interval [CI] 0.88-1.27), but there was an association for VT alerts from our new-unannotated algorithm (aHR 1.38; 95% CI 1.12-1.69) and true-annotated VT(aHR 1.39; 95% CI 1.12-1.73).

Conclusion

Unannotated and annotated-true VT were associated with increased rate of 30-day in-hospital mortality, whereas current bedside monitor VT was not. Our new algorithm may accurately identify high-risk VT; however, prospective validation is needed.

In memoriam: A tribute to the work and lives of Ron Selvester and Rory Childers

At the April, 2015 International Society for Computerized Electrocardiology (ISCE) Annual Conference in San Jose, CA, a special session entitled Remembering Ron & Rory was held to pay tribute to the extraordinary work and lives of two experts in electrocardiology. The session was well attended by conference attendees, Childers' family members and friends, and additional colleagues who traveled to San Jose solely to participate in this session. The purpose of the present paper is to document the spirit of this special session as faithfully as possible using the words of the session speakers.

Heart rate variability measurement and clinical depression in acute coronary syndrome patients: narrative review of recent literature

AIM

We aimed to explore links between heart rate variability (HRV) and clinical depression in patients with acute coronary syndrome (ACS), through a review of recent clinical research literature.

BACKGROUND

Patients with ACS are at risk for both cardiac autonomic dysfunction and clinical depression. Both conditions can negatively impact the ability to recover from an acute physiological insult, such as unstable angina or myocardial infarction, increasing the risk for adverse cardiovascular outcomes. HRV is recognized as a reflection of autonomic function.

METHODS

A narrative review was undertaken to evaluate state-of-the-art clinical research, using the PubMed database, January 2013. The search terms "heart rate variability" and "depression" were used in conjunction with "acute coronary syndrome", "unstable angina", or "myocardial infarction" to find clinical studies published within the past 10 years related to HRV and clinical depression, in patients with an ACS episode. Studies were included if HRV measurement and depression screening were undertaken during an ACS hospitalization or within 2 months of hospital discharge.

RESULTS

Nine clinical studies met the inclusion criteria. The studies' results indicate that there may be a relationship between abnormal HRV and clinical depression when assessed early after an ACS event, offering the possibility that these risk factors play a modest role in patient outcomes.

CONCLUSION

While a definitive conclusion about the relevance of HRV and clinical depression measurement in ACS patients would be premature, the literature suggests that these measures may provide additional information in risk assessment. Potential avenues for further research are proposed.

Prehospital electrocardiographic manifestations of acute myocardial ischemia independently predict adverse hospital outcomes

BACKGROUND

Prehospital electrocardiography (PH ECG) is becoming the standard of care for patients activating Emergency Medical Services for symptoms of acute coronary syndrome (ACS). Little is known about the prognostic value of ischemia found on PH ECG.

OBJECTIVE

The purpose of this study was to determine whether manifestations of acute myocardial ischemia on PH ECG are predictive of adverse hospital outcomes.

METHODS

This study was a retrospective analysis of all PH ECGs recorded in 630 patients who called 911 for symptoms of ACS and were enrolled in a prospective clinical trial. ST-segment monitoring software was added to the PH ECG device with automatic storage and transmission of ECGs to the destination Emergency Department. Patient medical records were reviewed for adverse hospital outcomes.

RESULTS

In 630 patients who called 911 for ACS symptoms, 270 (42.9%) had PH ECG evidence of ischemia. Overall, 37% of patients with PH ECG ischemia had adverse hospital outcomes compared with 27% of patients without PH ECG ischemia (p < 0.05). Those with PH ECG ischemia were 1.55 times more likely to have adverse hospital outcomes than those without PH ECG ischemia (95% CI 1.09-2.21; p < 0.05), after controlling for other predictors of adverse hospital outcomes (i.e., age, sex, and medical history).

CONCLUSIONS

Evidence of ischemia on PH ECG is an independent predictor of adverse hospital outcomes. ST-segment monitoring in the prehospital setting can identify high-risk patients with symptoms of ACS and provide important prognostic information at presentation to the Emergency Department.

A simple strategy improves prehospital electrocardiogram utilization and hospital treatment for patients with acute coronary syndrome (from the ST SMART Study)

Although the American Heart Association recommends a prehospital electrocardiogram (ECG) be recorded for all patients who access the emergency medical system with symptoms of acute coronary syndrome (ACS), widespread use of prehospital ECG has not been achieved in the United States. A 5-year prospective randomized clinical trial was conducted in a predominately rural county in northern California to test a simple strategy for acquiring and transmitting prehospital ECGs that involved minimal paramedic training and decision making. A 12-lead ECG was synthesized from 5 electrodes and continuous ST-segment monitoring was performed with ST-event ECGs automatically transmitted to the destination hospital emergency department. Patients randomized to the experimental group had their ECGs printed out in the emergency department with an audible voice alarm, whereas control patients had an ECG after hospital arrival, as was the standard of care in the county. The result was that nearly 3/4 (74%) of 4,219 patients with symptoms of ACS over the 4-year study enrollment period had a prehospital ECG. Mean time from 911 call to first ECG was 20 minutes in those with a prehospital ECG versus 79 minutes in those without a prehospital ECG (p <0.0001). Mean paramedic scene time in patients with a prehospital ECG was just 2 minutes longer than in those without a prehospital ECG (95% confidence interval 1.2 to 3.6, p <0.001). Patients with non-ST-elevation myocardial infarction or unstable angina pectoris had a faster time to first intravenous drug and there was a suggested trend for a faster door-to-balloon time and lower risk of mortality in patients with ST-elevation myocardial infarction. In conclusion, increased paramedic use of prehospital ECGs and decreased hospital treatment times for ACS are feasible with a simple approach tailored to characteristics of a local geographic region.

Preventing torsades de pointes by careful cardiac monitoring in hospital settings

In the electrocardiogram, the QT interval represents the time it takes the ventricular myocardium to repolarize. Prolongation of the QT interval indicates congenital or acquired abnormality of cardiac membrane channels. In the critical care setting, acquired long QT interval most commonly results from administration of common pharmacologic agents, including some antiarrhythmics and antibiotics. Patients with prolonged QT interval may be at risk for developing torsades de pointes and cardiac arrest. Furthermore, new-onset bradyarrhythmias and electrolyte disorders may increase this risk. Warning signs of impending sustained torsades de pointes include occurrence of polymorphic ventricular ectopic complexes, T-wave alternans, and nonsustained polymorphic ventricular tachycardia. Measurement and documentation of the QT interval, corrected for heart rate (QTc), is an important component of cardiac monitoring in the critical care setting. When prolonged QTc occurs in patients at risk, specific clinical interventions must be implemented to prevent the occurrence of torsades de pointes.

Novel electrocardiogram configurations and transmission procedures in the prehospital setting: effect on ischemia and arrhythmia determination

AIM

The aims of this report are to (1) describe a novel prehospital 12-lead electrocardiogram (ECG) configuration and transmission procedure used in the Synthesized Twelve-lead ST Monitoring and Real-time Tele-electrocardiography Study and to (2) report on the frequency of arrhythmias in field ECGs compared with the first hospital ECG.

METHODS

The Synthesized Twelve-lead ST Monitoring and Real-time Tele-electrocardiography Study is a 5-year randomized clinical trial ending in 2008. All emergency vehicles responding to 911 calls in Santa Cruz County, Calif, have been equipped with portable monitor defibrillators with a special study software that (1) synthesizes a 12-lead ECG from 5 electrodes, (2) measures ST amplitudes in all 12 leads every 30 seconds, and (3) automatically transmits an ECG to the target emergency department if there is a change in ST amplitude of 200 microV in 1 lead or more or 100 microV in 2 contiguous leads or more lasting 2.5 minutes. An initial ECG is transmitted by paramedics, which activates the software. Subsequent transmissions of ST event ECGs occur automatically without paramedic decision making.

RESULTS

Prehospital ECGs had a greater frequency of arrhythmias than the first hospital ECG in the group as a whole (n = 433; 33.3% vs 28.9%; P < or = .001), as well as the subgroup with acute coronary syndrome (n = 185; 30.3% vs 26.5%; P < or = .001). More tachyarrhythmias occurred in the field and slightly more bradyarrhythmias occurred at the time of the first hospital ECG.

CONCLUSIONS

Prehospital continuous 12-lead ST-segment ischemia monitoring with computer-assisted automatic mobile telephone transmission of ST event ECGs to the target hospital is feasible. More arrhythmias occur in the prehospital phase than are evident on the first hospital ECG.

Pre-hospital synthesized 12-lead ECG ischemia monitoring with trans-telephonic transmission in acute coronary syndromes

INTRODUCTION

The aim of the ST SMART trial is to determine whether prehospital ST monitoring with telephone transmission to the target hospital will improve hospital time to treatment in acute coronary syndromes. The present analysis reports results of the feasibility pilot study.

METHODS

All patients calling 911 for chest pain in Santa Cruz County California were monitored with a synthesized 12-lead ECG. Prehospital ECGs were printed for clinical use in the experimental group; control group patient care used only ECGs recorded after hospital arrival.

RESULTS

Five patients with non-ST elevation myocardial infarction or unstable angina had normal ECGs upon hospital arrival but evidence of ischemia in their prehospital ECGs. Three patients with ST elevation myocardial infarction were treated with primary percutaneous coronary intervention, with "door to balloon" times of 47 and 65 minutes in 2 experimental group patients and 148 minutes in the one control group patient.

CONCLUSION

Prehospital ST monitoring appears feasible. Its potential to improve hospital time to diagnosis and treatment in acute coronary syndromes, and the clinical benefits of such improvement will be studied in the larger, ongoing ST SMART trial.

Electrocardiographic repolarization abnormalities in subarachnoid hemorrhage

Electrocardiographic abnormalities, particularly in those waveforms representing ventricular repolarization, have been reported in subarachnoid hemorrhage. This study reports abnormalities on the initial electrocardiogram in 100 patients with SAH. Overall, one or more repolarization abnormalities occurred in 41% of patients. Analysis revealed prolonged QTc interval >460 ms in 16%, ST segment elevation in 9%, ST depression in 3%, T wave inversion in 7%, and U wave >or=100 microV in 15%. Electrocardiographic criteria for left ventricular hypertrophy were met in 14%, and 43% of those patients had no history of hypertension. Serum cardiac troponin I was elevated in 21%, and was significantly associated with QTc interval >460 ms (P <.001). Controlling for gender, those with QTc interval >460 ms were 5.5 times more likely to have elevated serum cardiac troponin I. It is concluded that repolarization abnormalities are present in a high proportion of patients with SAH. Some SAH patients also have left ventricular hypertrophy voltage unrelated to hypertension or coronary artery disease. Prolonged QTc interval after SAH is significantly related to myocardial injury, but unrelated to mortality, and there is no association between ST-T wave abnormalities and either myocardial injury or mortality.

Electrocardiographic abnormalities in patients with subarachnoid hemorrhage

Subarachnoid hemorrhage is a serious neurological disorder that is often complicated by the occurrence of electrocardiographic abnormalities unexplained by preexisting cardiac conditions. These morphological waveform changes and arrhythmias often are unrecognized or misinterpreted, potentially placing patients at risk for inappropriate management. Many previous investigations were retrospective and relied on data collected in an unsystematic manner. More recent studies that included use of serial electrocardiograms and Holter recordings have provided new insight into the high prevalence of electrocardiographic changes in subarachnoid hemorrhage. Research on the prevalence, duration, and clinical significance of these electrocardiographic abnormalities and on associated factors and etiological theories is reviewed.

Electrocardiographic Abnormalities in Patients With Subarachnoid Hemorrhage

Subarachnoid hemorrhage is a serious neurological disorder that is often complicated by the occurrence of electrocardiographic abnormalities unexplained by preexisting cardiac conditions. These morphological waveform changes and arrhythmias often are unrecognized or misinterpreted, potentially placing patients at risk for inappropriate management. Many previous investigations were retrospective and relied on data collected in an unsystematic manner. More recent studies that included use of serial electrocardiograms and Holter recordings have provided new insight into the high prevalence of electrocardiographic changes in subarachnoid hemorrhage. Research on the prevalence, duration, and clinical significance of these electrocardiographic abnormalities and on associated factors and etiological theories is reviewed.

Environmental hazards in the technological age

The proliferation of technology in critical care has intensified the potential for illness or injury due to physical hazards, which are hazards associated with the transfer of energy from the environment to a person. These are generated most commonly by machines or medical devices. Known and suspected physical hazards, including radiant energy, electricity, and noise are discussed, along with their health implications and effective preventive strategies. Areas for future research are identified.

Violence as an occupational hazard in the acute care setting

In this article, the author explores the issue of violence in the inpatient and outpatient hospital setting. Only recently recognized as a significant occupational hazard to nurses, violence can lead not only to physical injury but also to prolonged and debilitating emotional, social, biophysiologic, and cognitive symptoms. The prevalence of the problem is presented, followed by a discussion of contributory factors and the effects violent incidents may have on victims. Strategies for prevention and topics for future research are identified.