Predictors of cardiogenic shock in cardiac surgery patients receiving intra-aortic balloon pumps

BACKGROUND

Cardiogenic shock after cardiac surgery leads to severely increased mortality. Intra-aortic balloon pumps may be used during the preoperative period to increase coronary perfusion. The purpose of this study was to characterize predictors of postoperative cardiogenic shock in cardiac surgery patients with and without intra-aortic balloon pumps support.

METHODS

We performed a retrospective analysis of our institutional database of the Society of Thoracic Surgeons for patients operated between January 2008 to July 2015. Multivariable logistic regression was used to model postoperative cardiogenic shock in both the intra-aortic balloon pumps and matched control cohorts.

RESULTS

Overall, 4,741 cardiac surgery patients were identified during the study period, of whom 192 (4%) received a preoperative intra-aortic balloon pump. Intra-aortic balloon pumps patients had a greater prevalence of diabetes, previous cardiac surgery, congestive heart failure, and an urgent/emergent status (P < .001). Intra-aortic balloon pumps patients also had greater 30-day mortality and more postoperative cardiogenic shock (9% vs 3%, P < .001). On multivariable analysis of the matched control cohort, postoperative cardiogenic shock remained multifactorial. Among the intra-aortic balloon pumps cohort, only sex, previous percutaneous coronary intervention and preoperative arrhythmia remained significant on multivariable analysis (all P < .05).

CONCLUSION

Factors associated with cardiogenic shock among postcardiac surgery patients differ between those patients receiving intra-aortic balloon pumps and those who do not. Further analysis of the effects of prophylactic intra-aortic balloon pumps support is warranted. (Surgery 2017;160:XXX-XXX.).

Incidence of Myocardial Infarction After High-Risk Vascular Operations in Adults

Importance

Advances in perioperative cardiac management and an increase in the number of endovascular procedures have made significant contributions to patients and postoperative myocardial infarction (POMI) risk following high-risk vascular procedures. Whether these changes have translated into real-world improvements in POMI incidence remain unknown.

Objective

To examine the temporal trends of myocardial infarction (MI) following high-risk vascular procedures.

Design, Setting, and Participants

A retrospective cohort study was performed using data collected from January 1, 2005, to December 31, 2013, in the American College of Surgeons National Surgery Quality Improvement Program database, to which participating hospitals across the United States report their preoperative, operative, and 30-day outcome data. A total of 90 303 adults who underwent a high-risk vascular procedure-open aortic surgery or infrainguinal bypass-during the study period were identified. Patients were divided into cohorts based on their year of operation, and their baseline cardiac risk factors and incidence of POMI were compared. Cases from 2005 to 2014 in the database were eligible for inclusion if one of their Current Procedural Terminology codes matched any of the operations identified as a high-risk vascular procedure. Data analysis took place from August 1, 2016, to November 15, 2016.

Exposures

The main exposure was the year of the operation. Other variables of interest included demographics, comorbidities, and other risk factors for MI.

Main Outcomes and Measures

Primary outcome of interest was the incidence of POMI.

Results

Of the 90 303 patients included in the study, 22 836 (25.3%) had undergone open aortic surgery and 67 467 (74.7%) had had infrainguinal bypass. The open aortic cohort comprised 16 391 men (71.9%), had a mean (SD) age of 69.1 (11.5) years, and was predominantly white (18 440 patients [80.8%] self-identified as white race/ethnicity). The infrainguinal bypass cohort included 41 845 men (62.1%), had a mean (SD) age of 66.7 (11.7) years, and had 51 043 patients (75.7%) who self-identified as white race/ethnicity. During the study period, patients who underwent open aortic procedures were more likely to be classified as American Society of Anesthesiologists class IV (7426 patients [32.6%] vs 15 683 [23.3%] for the infrainguinal bypass cohort) or class V (1131 [5.0%] vs 206 [0.3%]; P < .001) and to undergo emergency procedures (4852 [21.3%] vs 4954 [7.3%]; P < .001). The open aortic procedure cohort also experienced significantly higher actual incidence of POMI (464 [3.0%] vs 1270 [1.9%]; P < .001). From 2009 to 2014, the incidence of POMI demonstrated no substantial temporal change (2.7% in 2009 to 3.1% in 2014; P = .64 for trend). Postoperative MI was consistently associated with poor prognosis, with a 3.62-fold (95% CI, 2.25-5.82) to 11.77-fold (95% CI, 6.10-22.72) increased odds of cardiac arrest and a 3.01-fold (95% CI, 2.08-4.36) to 6.66-fold (95% CI, 4.66-9.52) increased odds of mortality.

Conclusions and Relevance

The incidence of MI did not significantly decrease in the past decade and has been consistently associated with worse clinical outcomes. Further inquiry into why advanced perioperative care did not reduce cardiac complications is important to quality improvement efforts.

Hybrid surgical vs percutaneous access epicardial ventricular tachycardia ablation

BACKGROUND

There is limited experience of surgical epicardial access in the contemporary era of ventricular tachycardia ablation after cardiac surgery.

OBJECTIVES

The purpose of this study was to describe our institutional experience with surgical epicardial access and the influence of surgical approach and compare outcomes with those of a propensity-matched percutaneous epicardial access control group.

METHODS

We performed a retrospective study of consecutive surgical epicardial ventricular tachycardia (VT) ablation cases from a single center. Surgical cases were propensity-matched to percutaneous epicardial ablation controls and short-term and long-term outcomes were compared.

RESULTS

Between 2004 and 2016, 38 patients underwent 40 surgical epicardial access procedures (subxiphoid, n = 22; thoracotomy, n = 18). The commonest indication was prior coronary artery bypass grafting (45%), valve surgery (22%), or ventricular assist device (VAD) (10%). The mean procedure time was 444 minutes (standard deviation, 107 minutes). Mapped epicardial geometry area was 149 cm² (interquartile range 182 cm²), which comprised 36% of the mapped epicardial geometric area of a percutaneous control group. Subxiphoid access gave preferential access to the inferior and inferolateral left ventricular segments and was less frequently able to access the anterior, anterolateral, and apical segments compared with a thoracotomy approach. When compared with results from a propensity-matched percutaneous-access group, short-term outcomes, complication rates, and 1-year survival free from a combined end point of VT recurrence, death, or transplantation were not statistically different.

CONCLUSIONS

Surgical epicardial access after cardiac surgery for ablation of VT in patients with careful preprocedure evaluation can be performed with acceptable safety with no statistical difference in long-term outcomes compared with a propensity-matched percutaneous epicardial cohort. The region of left ventricular epicardium that can be mapped is limited compared with that of percutaneous cases and is determined by the surgical approach.

Does Travel Distance Affect Readmission Rates after Cardiac Surgery?

With emphasis on value-based health care, empiric models are used to estimate expected readmission rates for individual institutions. The aim of this study was to determine the relationship between distance traveled to seek surgical care and likelihood of readmission in adult patients undergoing cardiac operations at a single medical center. All adults undergoing major cardiac surgeries from 2008 to 2015 were included. Patients were stratified by travel distance into regional and distant travel groups. Multivariable logistic regression models were developed to assess the impact of distance traveled on odds of readmission. Of the 4232 patients analyzed, 29 per cent were in the regional group and 71 per cent in the distant. Baseline characteristics between the two groups were comparable except mean age (62 vs 61 years, P < 0.01) and Caucasian race (59 vs 73%, P < 0.01). Distant travel was associated with a significantly longer hospital length of stay (11.8 vs 10.5 days, P < 0.01) and lower risk of readmission (9.5 vs 13.4%, P < 0.01). Odds of readmission was inversely associated with logarithm of distance traveled (odds ratio 0.75). Travel distance in patients undergoing major cardiac surgeries was inversely associated with odds of readmission.

Current Methods and Advances in Simulation of Hemorrhage after Trauma

As animal models fall out of favor, there is demand for simulators to train medical personnel in the management of trauma and hemorrhage. Realism is essential to the development of simulators for training in the management of trauma and hemorrhage, but is difficult to achieve because it is difficult to create models that accurately represent bleeding organs. We present a simulation platform that uses real-time mathematical modeling of hemodynamics after hemorrhage and trauma and visually represents the injury described by the model. Using patient-specific imaging, 3D-mesh representations of the liver were created and merged with an anatomically accurate vascular tree. By using anatomically accurate representations of the vasculature, we were able to model the cardiovascular response to hemorrhage in a specific artery. The incorporation of autonomic tone allowed for the calculation of bleeding rate and aortic pressures. The 3D-mesh representation of the liver allowed us to simulate blood flow from the liver after trauma. For the first time, we have successfully incorporated tissue modeling and fluid dynamics with a model of the cardiovascular system to create a simulator. These simulations may aid in the creation of realistic virtual environments for training.

Current Methods and Advances in Simulation of Hemorrhage after Trauma

As animal models fall out of favor, there is demand for simulators to train medical personnel in the management of trauma and hemorrhage. Realism is essential to the development of simulators for training in the management of trauma and hemorrhage, but is difficult to achieve because it is difficult to create models that accurately represent bleeding organs. We present a simulation platform that uses real-time mathematical modeling of hemodynamics after hemorrhage and trauma and visually represents the injury described by the model. Using patient-specific imaging, 3D-mesh representations of the liver were created and merged with an anatomically accurate vascular tree. By using anatomically accurate representations of the vasculature, we were able to model the cardiovascular response to hemorrhage in a specific artery. The incorporation of autonomic tone allowed for the calculation of bleeding rate and aortic pressures. The 3D-mesh representation of the liver allowed us to simulate blood flow from the liver after trauma. For the first time, we have successfully incorporated tissue modeling and fluid dynamics with a model of the cardiovascular system to create a simulator. These simulations may aid in the creation of realistic virtual environments for training.

Does Travel Distance Affect Readmission Rates after Cardiac Surgery?

With emphasis on value-based health care, empiric models are used to estimate expected read-mission rates for individual institutions. The aim of this study was to determine the relationship between distance traveled to seek surgical care and likelihood of readmission in adult patients undergoing cardiac operations at a single medical center. All adults undergoing major cardiac surgeries from 2008 to 2015 were included. Patients were stratified by travel distance into regional and distant travel groups. Multivariable logistic regression models were developed to assess the impact of distance traveled on odds of readmission. Of the 4232 patients analyzed, 29 per cent were in the regional group and 71 per cent in the distant. Baseline characteristics between the two groups were comparable except mean age (62 vs 61 years, P < 0.01) and Caucasian race (59 vs 73%, P < 0.01). Distant travel was associated with a significantly longer hospital length of stay (11.8 vs 10.5 days, P < 0.01) and lower risk of readmission (9.5 vs 13.4%, P < 0.01). Odds of readmission was inversely associated with logarithm of distance traveled (odds ratio 0.75). Travel distance in patients undergoing major cardiac surgeries was inversely associated with odds of readmission.

Effect of thoracic epidural anesthesia on heart rate variability in a porcine model

Heart rate variability (HRV) is increasingly recognized as a means of evaluating autonomic tone. Thoracic epidural anesthesia (TEA) has been previously demonstrated to suppress the electrical storms in patients. However, the effect of TEA on HRV during sympathoexcitation remains unknown. In this study, we aimed to determine the effects of TEA on HRV response to left stellate ganglion stimulation (LSS) in a porcine model. In 12 anesthetized pigs after insertion of an epidural catheter to T1 level, a median sternotomy was performed to expose the heart and the left stellate ganglion. A 56‐electrode sock was used for obtaining epicardial activation recovery interval (ARI). Animal received LSS at 4 Hz for 30 sec. After 30 min of bupivacaine epidural injection, LSS was performed in the same way as the baseline condition. LSS significantly increased low‐frequency normalized units (LF: 44.9 ± 6.7 vs. 13.6 ± 3.1 msec² baseline, P < 0.05) and decreased high‐frequency normalized units (HF: 11.5 ± 4.6 vs. 41.9 ± 5.1 msec² baseline, P < 0.05). As a result, LF/HF significantly increased from 0.3 ± 0.2 to 3.9 ± 1.4 during LSS. TEA significantly attenuated the LF/HF from 3.9 ± 1.4 to 1.6 ± 0.8 with increased HF components from 11.5 ± 4.6 to 26.5 ± 3.2 msec². LF component significantly correlates with global ARI (r = −0.81) and dispersion of repolarization (r = 0.85). HRV can precisely reflect the cardiac autonomic tone and TEA modulates the HRV by enhancing the HF components probably through a parasympathetic nerve system.

Dysphagia after Cardiac Operations is Associated with Increased Length of Stay and Costs

Although the true incidence of postoperative dysphagia after cardiac surgery is unknown, it has been reported to occur in 3 to 21.6 per cent of patients. Historically, dysphagia has been associated with increased surgical complications and prolonged hospital stay. This study aimed to evaluate the costs and outcomes associated with dysphagia after cardiac surgery. Patients undergoing nonemergent, nontransplant cardiac operations between June 2013 and June 2014 were eligible for inclusion. Independent predictors of cost were identified through a multivariate linear regression model. Of the 354 patients (35% female) included for analysis, 56 (16%) were diagnosed with postoperative dysphagia. On univariate analysis, patients with dysphagia had increased intensive care unit and total hospital lengths of stay (11.8 vs 5.2 days, P < 0.001 and 18.2 vs 9.7 days, P < 0.001, respectively), and a 57 ± 15 per cent increase in cost of care ( P < 0.001). Dysphagia was not associated with higher rates of in-hospital mortality (3.6% vs 3.0%, P = 0.83). On multivariate linear regression, the development of dysphagia was independently associated with a 45.1 per cent increase in total hospital costs [95% confidence interval (31% and 59%), P < 0.001]. Dysphagia is an independent and major contributor to health care costs after cardiac operations, suggesting that postoperative dysphagia represents a highly suitable target for quality improvement and cost containment efforts.

Surgical Hand Tracking in Open Surgery Using a Versatile Motion Sensing System: Are We There Yet?

With changes in work hour limitations, there is an increasing need for objective determination of technical proficiency. Electromagnetic hand-motion analysis has previously shown only time to completion and number of movements to correlation with expertise. The present study was undertaken to evaluate the efficacy of hand-motion-tracking analysis in determining surgical skill proficiency. A nine-degree-of-freedom sensor was used and mounted on the superior aspect of a needle driver. A one-way analysis of variance and Welch's t test were performed to evaluate significance between subjects. Four Novices, four Trainees, and three Experts performed a large vessel patch anastomosis on a phantom tissue. Path length, total number of movements, absolute velocity, and total time were analyzed between groups. Compared to the Novices, Expert subjects exhibited significantly decreased total number of movements, decreased instrument path length, and decreased total time to complete tasks. There were no significant differences found in absolute velocity between groups. In this pilot study, we have identified significant differences in patterns of motion between Novice and Expert subjects. These data warrant further analysis for its predictive value in larger cohorts at different levels of training and may be a useful tool in competence-based training paradigms in the future.

Use of preoperative aspirin in combined coronary and valve operations

BACKGROUND

The aim of this study was to determine the relationship between preoperative aspirin use and postoperative outcomes in patients undergoing combined coronary artery bypass grafting and valve operations.

METHODS

All combined coronary artery bypass grafting and valve procedures from 2008 to 2015 at our institution were identified. After exclusions, patients were stratified according to those that received preoperative aspirin and those who did not. Propensity score methodology was used to match the 2 groups using baseline and operative characteristics. Logistic regression models were then developed to assess differences in postoperative outcomes between groups.

RESULTS

Of the 563 patients identified, 534 met inclusion criteria: preoperative aspirin = 327 (61.2%), no preoperative aspirin = 207 (38.8%). After propensity matching, 194 patient pairs were analyzed, with no significant differences in preoperative characteristics. No significant differences were observed between the preoperative aspirin and no preoperative aspirin groups in rates of 30-day mortality (3.6% vs 4.1%, P = 1.00), major adverse cardiovascular events (23.2% vs 24.2%, P = .91), or 30-day readmission (12.4% vs 11.9%, P = 1.00), among others.

CONCLUSION

Preoperative aspirin use in patients undergoing combined coronary artery bypass grafting and valve operations was not associated with significant differences in major postoperative outcomes. Large-scale, randomized trials are needed to better establish the role of preoperative aspirin in this population.

Neuromodulation of Limb Proprioceptive Afferents Decreases Apnea of Prematurity and Accompanying Intermittent Hypoxia and Bradycardia

BACKGROUND

Apnea of Prematurity (AOP) is common, affecting the majority of infants born at <34 weeks gestational age. Apnea and periodic breathing are accompanied by intermittent hypoxia (IH). Animal and human studies demonstrate that IH exposure contributes to multiple pathologies, including retinopathy of prematurity (ROP), injury to sympathetic ganglia regulating cardiovascular action, impaired pancreatic islet cell and bone development, cerebellar injury, and neurodevelopmental disabilities. Current standard of care for AOP/IH includes prone positioning, positive pressure ventilation, and methylxanthine therapy; these interventions are inadequate, and not optimal for early development.

OBJECTIVE

The objective is to support breathing in premature infants by using a simple, non-invasive vibratory device placed over limb proprioceptor fibers, an intervention using the principle that limb movements trigger reflexive facilitation of breathing.

METHODS

Premature infants (23-34 wks gestational age), with clinical evidence of AOP/IH episodes were enrolled 1 week after birth. Caffeine treatment was not a reason for exclusion. Small vibration devices were placed on one hand and one foot and activated in 6 hour ON/OFF sequences for a total of 24 hours. Heart rate, respiratory rate, oxygen saturation (SpO2), and breathing pauses were continuously collected.

RESULTS

Fewer respiratory pauses occurred during vibration periods, relative to baseline (p<0.005). Significantly fewer SpO2 declines occurred with vibration (p<0.05), relative to control periods. Significantly fewer bradycardic events occurred during vibration periods, relative to no vibration periods (p<0.05).

CONCLUSIONS

In premature neonates, limb proprioceptive stimulation, simulating limb movement, reduces breathing pauses and IH episodes, and lowers the number of bradycardic events that accompany aberrant breathing episodes. This low-cost neuromodulatory procedure has the potential to provide a non-invasive intervention to reduce apnea, bradycardia and intermittent hypoxia in premature neonates.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02641249.

Temporary Venoarterial Extracorporeal Membrane Oxygenation: Ten-Year Experience at a Cardiac Transplant Center

Objective:

Advances in extracorporeal membrane oxygenation (ECMO) have enabled rapid deployment in a wide range of clinical settings. We report our experience with venoarterial (VA) ECMO in adult patients over 10 years and aim to identify predictors of mortality.

Design:

This is a retrospective analysis of all adult patients undergoing VA ECMO at a tertiary care center from January 1, 2004, to December 31, 2013.

Results:

A total of 224 consecutive cases were reviewed. Eighty (35.7%) patients survived to discharge and 144 (64.3%) patients died. Patients requiring ECMO for heart transplant graft failure had lower mortality (51.6%) compared to all other etiologies (69.1%; P = .02). Forty-two percent (94 of the 224) of the patients required cardiopulmonary resuscitation (CPR) preceding ECMO and had higher rate of in-hospital mortality (74.5%) compared with patients without cardiac arrest (56.9%; P = .01). Patients with less than 30 minutes of CPR had a mortality rate of 40.0% compared to 91.4% for CPR > 30 minutes ( P = .001). In all, 24.1% of patients (54 of the 224) experienced ECMO-associated complications without significant increase in mortality, and 22.3% (50 of the 224) of the patients were transitioned to ventricular assist devices (VADs) or transplant. Patients bridged to a VAD including left ventricular assist devices and biventricular assist devices had a mortality rate of 56.1% versus 22.2% when bridged directly to transplant ( P = .01). Paradoxically, patients with an ejection fraction (EF) > 35% had a higher mortality compared to patients with an EF < 35% (75.3% vs 49.4%, respectively, P = .001).

Conclusion:

Extracorporeal membrane oxygenation in patients with heart transplant graft failure had the best outcome. In patients who had cardiac arrest, prolonged CPR > 30 minutes was associated with very high mortality. Paradoxically, patients with EF > 35% had a higher mortality than patients with EF < 35%, likely reflecting patients with diastolic heart failure or noncardiac causes necessitating ECMO. For transplant candidates, direct bridge from ECMO to transplant could achieve a very good outcome.