Intraaortic balloon counterpulsation: patterns of usage and outcome in cardiac surgery patients

Intra-aortic balloon pump postcardiac surgery: A literature review

Intra-aortic balloon pump (IABP) has been the most commonly used mechanical assist circulatory device in many postcardiotomy low output disorders for decades. Mechanism of IABP is based on its inflation in time of the diastolic pressure in the aortic root resulting increase in the blood and oxygen amount of the coronary artery and its deflation in left ventricular afterload during the systolic period. Prophylactic and postoperative application of IABP has been suggested by researchers, which has been commonly used in high-risk patients undertaking coronary artery bypass grafting surgery or percutaneous coronary intervention. Other researchers put forward the idea of the percutaneous IABP insertion throughout the left axillary artery as a reliable and relatively well-tolerated approach and also as a recovery tool to bridge patients with end-stage heart failure to heart transplantation. The current review was aimed to give further insight into routine IABP application by presenting the basic principles and trends in the incidence, management, role of IABP recovery, and long-lasting mortality outcomes in patients with cardiovascular disorders and discussing previous and current evidence.

Combined association of liver and renal injury by intra-aortic balloon pump malposition

BACKGROUND

We report an unusual visceral complication of intra-aortic balloon pump (IABP) due to the malpositioning of the catheter in the aorta.

CASE REPORT

A 55-year-old man with severe left ventricular dysfunction underwent coronary artery bypass grafting (CABG) with the preoperative use of an intra-aortic balloon pump. Postoperative course was complicated by renal and hepatic failure. The early occurrence of complications during 36 hours after operation exhibited a serious vascular complication. The combination of acute renal and hepatic failure led to the suspension to occlusive effect of intra-aortic balloon pump catheter on ostium of the aforementioned organs. The intra-aortic balloon pump was removed, and urine output immediately restored. Thereafter, daily slop dawn serum levels of aminotransferases were started, and became normal at the 10th day of operation.

CONCLUSION

This is an exceptional case that shows how intra-aortic balloon pump may be contributed to mechanical aortic side branches obstruction. A high index of suspension is mandatory in the diagnosis of such bizarre complications.

Intra-aortic balloon pump experience: a single center study comparing with and without sheath insertion

Introduction: The mechanical circulation support used in treatment of low cardiac output at most is the intra-aortic balloon pump (IABP). Its usage fields are the complications occurring due to ischemic heart disease, disrupted left ventricle function, and the low cardiac output syndrome occurring during coronary artery by-pass surgery.

Methods: During 28 years from 1985 to 2013, IABP support has been implemented to 3135 patients in our cardiac surgery operating theater and intensive care unit. The mean age of the patients was 61.4 ± 13.2 years (16-82). 2506 patients (80%) were the ones whom the cardiac surgery has been implemented. IABP support has been provided for 629 (20%) patients for medical treatment. We utilized IABP most frequently in coronary artery patients (70%). The first choice for placing the balloon catheter is the femoral artery in 3093 cases (98.7%).

Results: The most frequently observed balloon complication was the lower extremity ischemia in 383 cases (12.2%).The leg ischemia was statistically significantly more frequent in patients with sheath (P=0.004). The extremity ischemia has developed in 4 of 12 patients with balloon placed from upper extremity. The local bleeding and balloon rupture were more frequent in patients whom the balloon has been placed without sheath. The mortality due to IABP has occurred in only 5 patients.

Conclusion: Despite increase in IABP usage frequency rapidly, the complications due to catheter are still seen. We believe that the leg ischemia that is the most frequently seen complication can be prevented via IABP use without sheath.

The Enabler Cannula Pump: A Novel Circulatory Support System

Background

The enabler circulatory support system is a catheter pump which expels blood from the left or right ventricular cavity and provides pulsatile flow in the ascending aorta or pulmonary artery. It is driven by a bedside installed pulsatile driving console. The device can easily be implanted by a minimal invasive approach, similar to the Hemopump.

Purpose

To demonstrate the hemodynamic performance of this new intracardiac support system.

Methods

In a series of 9 sheep, hemodynamic evolutions were recorded in various conditions of myocardial contractility (the non-failing, the moderately failing and the severely failing heart). Heart failure was induced by injection of microspheres in the coronary arteries.

Results

Introduction of the cannula through the aortic valve was feasible in all cases. Pump flow by the enabler was gradually increased to a maximum of 3.5 L/min. Diastolic (and mean) aortic blood pressure is significantly increased in the non-failing and moderately failing condition (counterpulsation mode). In heart failure, cardiac output is significantly increased by the pump (p<0.0001). A drop in left atrial pressure (indicating unloading) is achieved in all conditions but reaches significant levels only during heart failure (p=0.0068).

Conclusions

This new circulatory support system contributes to stabilization of the circulation in the presence of cardiac unloading. In heart failure it actually supports the circulation by increasing cardiac output and perfusion pressure.

Prophylactic Intra-Aortic Balloon Pump Before Ventricular Assist Device Implantation Reduces Perioperative Medical Expenses and Improves Postoperative Clinical Course in INTERMACS Profile 2 Patients

BACKGROUND

Although intra-aortic balloon pump (IABP) is sometimes used before cardiac surgery to achieve better outcome in high-risk patients, the clinical impact of prophylactic IABP support before left ventricular assist device (LVAD) implantation in patients with worsening hemodynamics was unknown.

METHODS AND RESULTS

We enrolled 22 patients with worsening hemodynamics who had received IABP support before LVAD (IABP group), and also enrolled 22 patients receiving neither IABP nor extracorporeal membrane oxygenation before LVAD, who were selected on propensity score matching (non-IABP group). Although both groups had similar preoperative background, the IABP group had shorter postoperative intensive care unit (ICU) stay, and more improved hemodynamics (P<0.05 for all). Serum total bilirubin and creatinine decreased significantly in the IABP group compared with the non-IABP group during 1 month after LVAD implantation (P<0.05 for both). Medical expenses during perioperative ICU stay were significantly lower in the IABP group compared with the non-IABP group, even including the cost of preoperative IABP support (P<0.05).

CONCLUSIONS

Prophylactic IABP support in heart failure patients with worsening hemodynamics improves post-LVAD clinical course and reduces perioperative medical expenses.

Polar–nonpolar interconnected elastic networks with increased permittivity and high breakdown fields for dielectric elastomer transducers

Polysiloxanes with polar cyano groups were cross-linked with PDMS by a hydrolysis–condensation process. Materials suitable for transducer applications with improved permittivity, good mechanical properties, and high breakdown fields were obtained.

Temporal trends in the use of intraaortic balloon pump associated with percutaneous coronary intervention in the United States, 1998-2008

BACKGROUND

With conflicting evidence regarding the usefulness of intraaortic balloon pump (IABP), reports of IABP use in the United States have been inconsistent. Our objective was to examine trends in IABP usage in percutaneous coronary intervention (PCI) in the United States and to evaluate the association of IABP use with mortality.

METHODS

This is a retrospective, observational study using patient data obtained from the Nationwide Inpatient Sample database from 1998 to 2008. Patients undergoing any PCI (1,552,602 procedures) for a primary diagnosis of symptomatic coronary artery disease and acute coronary syndrome, including non-ST-elevation myocardial infarction and ST-elevation myocardial infarction, were evaluated.

RESULTS

The overall use of IABP significantly decreased during the study period from 0.99% in 1998 to 0.36% in 2008 (univariate and multivariate P for trend < .0001). Patients who received IABP had substantially higher rates of shock compared with those who did not receive IABP (38.09% vs 0.70%; P < .0001), which was associated with markedly higher inhospital mortality rates (20.31% vs 0.72%; P < .0001). However, IABP use significantly decreased in patients with shock (36.5%-13.4%) and acute myocardial infarction (2.23%-0.84%) (univariate and multivariate P for trend for both < .0001). A temporal reduction in all-cause PCI-associated mortality from 1.1% in 1998 to 0.86% in 2008 (univariate and multivariate P for trend < .0001) was also observed.

CONCLUSIONS

The utilization of IABP associated with PCI significantly decreased between 1998 and 2008 in the United States, even among patients with acute myocardial infarction and shock.

Efficacy of prophylactic intra-aortic balloon pump therapy in chronic heart failure patients undergoing cardiac surgery

This study investigated the efficacy of prophylactic intraoperative intra-aortic balloon pump (IABP) usage in chronic heart failure patients with severely reduced left ventricular function undergoing elective cardiac surgery. Between January 2008 and December 2012, 107 patients with severely reduced left ventricular ejection fraction (LVEF <35%) received prophylactic intraoperative IABP implantation during open-heart surgery. Surgical procedures performed were isolated coronary artery bypass grafting (CABG) in 35 patients (32.7%), aortic valve replacement in 12 (11.2%), mitral valve repair or replacement in 15 (14.0%), combined valve and CABG procedures in 27 (25.2%), and other surgical procedures in 18 (16.8%). Results and outcomes were compared with those in a propensity score-matched cohort of 107 patients who underwent cardiac surgery without intraoperative IABP implantation. Matching criteria were age, gender, LVEF, and surgical procedure. Duration of intensive care unit (ICU) stay, duration of hospital stay, and 30-day mortality were markers of outcome. In the IABP group, mean patient age was 69.1 ± 13.7 years; 66.4% (70) were male. All IABPs were placed intraoperatively. Mean duration of IABP application time was 42.4 ± 8.7 h. IABP-related complications occurred in five patients (4.7%), including one case of inguinal bleeding, one case of mesenteric ischemia, and ischemia of the lower limb in three patients. No stroke or major bleeding occurred during IABP support. Mean durations of ICU and hospital stay were 3.38 ± 2.15 days and 7.69 ± 2.02 days, respectively, in the IABP group, and 4.20 ± 3.14 days and 8.57 ± 3.26 days in the control group, showing statistically significant reductions in duration of ICU and hospital stay in the IABP group (ICU stay, P = 0.036; hospital stay, P = 0.015). Thirty-day survival rates were 92.5 and 94.4% in the IABP and control group, respectively, showing no statistically significant difference (P = 0.75). IABP usage in chronic heart failure patients with severely reduced LVEF undergoing cardiac surgery was safe and resulted in shorter ICU and hospital stay but did not influence 7- and 30-day survival rates.

Risk modeling for ventricular assist device support in post-cardiotomy shock

BACKGROUND

Post-cardiotomy shock (PCS) has a complex etiology. Although treatment with inotrops and intra-aortic balloon pump (IABP) support improves cardiac performance, end-organ injuries are common and lead to prolonged ICU stay, extended hospitalization and increased mortality. Early consideration of mechanical circulatory support may prevent such complications and improve outcome.

METHODS

Between January 1997 and January 2002, 321 patients required IABP and inotropic support for PCS following coronary artery bypass grafting (CABG) at our institution. Perioperative variables including age, mixed venous saturation (MVO2), inotropic requirements and LV function were analyzed using multivariate statistical methods. All explanatory variables with a univariate p value <0.10 were entered into a stepwise logistic regression model to predict hospital mortality. Odds ratios from significant variables (p < 0.05) in the regression model were used to compose a risk score.

RESULTS

Overall hospital mortality was 16%. The independent risk factors for mortality in this population were: MVO2 < 60% (OR = 3.2), milrinone > 0.5 μg/kg/min (OR = 3.2), age > 75 (OR = 2.7), adrenaline > 0.1 μg/kg/min (OR = 1.5). A 15-point risk score was developed based on the regression model. Hospital mortality in patients with a score >6 was 46% (n = 13/28), 3-6 was 31% (n = 9/29) and <3 was 11% (n = 29/264).

CONCLUSIONS

A significant proportion of patients with PCS continue to face high mortality despite IABP and inotropic support. Advanced age, heavy inotropic dependency and poor oxygen delivery all predicted increased risk for death. Further investigation is needed to assess whether early institution of VAD support could improve outcome in this high-risk group of patients.

The magnitude of the T cell response to a clinically significant dose of influenza virus is regulated by TRAIL

An immune response of appropriate magnitude should be robust enough to control pathogen spread but not simultaneously lead to immunopathology. Primary infection with influenza A virus (IAV) results in a localized pulmonary infection and inflammation and elicits an IAV-specific CD8 T cell immune response necessary for viral clearance. Clearance of IAV-infected cells, and recovery from infection, is mediated by perforin/granzyme B- and Fas/FasL-mediated mechanisms. We recently reported that TRAIL is another means by which IAV-specific CD8 T cells can kill IAV-infected cells. The current study examined the role of TRAIL in the pulmonary CD8 T cell response to a clinically significant IAV [A/PR/8/34 (PR8; H1N1)] infection (i.e., leads to observable, but limited, morbidity and mortality in wild-type [WT] mice). Compared with WT mice, IAV-infected Trail(-/-) mice experienced increased morbidity and mortality despite similar rates of viral clearance from the lungs. The increased morbidity and mortality in Trail(-/-) mice correlated with increased pulmonary pathology and inflammatory chemokine production. Analysis of lung-infiltrating lymphocytes revealed increased numbers of IAV-specific CD8 T cells in infected Trail(-/-) mice, which correlated with increased pulmonary cytotoxic activity and increased pulmonary expression of MIG and MIP-1α. In addition, there was decreased apoptosis and increased proliferation of IAV-specific CD8 T cells in the lungs of Trail(-/-) mice compared with WT mice. Together, these data suggest that TRAIL regulates the magnitude of the IAV-specific CD8 T cell response during a clinically significant IAV infection to decrease the chance for infection-induced immunopathology.

Open chest management after cardiac operations: outcome and timing of delayed sternal closure

OBJECTIVE

Open chest management (OCM) after cardiac surgery is a therapeutic option in the treatment of the severely impaired heart. The aim of this study was the evaluation of the incidence, survival and predictors of poor outcome for OCM with delayed sternal closure (DSC), particularly with regard to parameters to determine the time of closure.

METHODS

Prolonged open chest was used in 212 of 6041 cardiac surgery patients between 2004 and 2009 (3.5%). We wanted to determine indications, mortality, morbidity, predictors of outcome, and parameters for timing of sternal closure.

RESULTS

The incidence of open chest (OC) was 3.5%, with 1.4% for isolated coronary artery bypass grafting (CABG), 2.9% for isolated valve, and 7.1% for combined procedures. Indications for OC were: hemodynamic compromise (180), intractable bleeding (14), arrhythmia (12), and cardiac edema or tamponade (six). A total of 153 of the 212 patients with DSC (72%) survived. Fifty-nine patients died: 23 before DSC and 36 after this procedure. Mortality could be related to the indication for OC: With the indication 'low cardiac output syndrome' (LCOS), the mortality was 36%, for bleeding it was 25.5%, for arrhythmias 20.5%, and for tamponade on closure it was 18%. After DSC, deep sternal wound infection (DSWI) occurred in 10 patients (5.3%) and superficial infection in 4.8% of patients. There were 18 patients with postoperative stroke (8.5%) and 27 patients with need for dialysis (12.7%). By univariate analysis, ventricular assist device (VAD) insertion, new onset of hemodialysis, re-operation for bleeding, mean length of duration of OC (survivors 3.2 days, non-survivors 6.4 days), and longer duration of high-dose inotropic therapy could be determined as predictors of mortality.

CONCLUSION

With our results, we could demonstrate OCM to be a beneficial, therapeutic option in patients with postoperative LCOS, massive hemorrhage or significant arrhythmias with hemodynamic compromise. However, patients with re-operation for bleeding, need for VAD and particularly a prolonged delay before sternal closure continued to have a poor outcome.

Visceral arterial compromise during intra-aortic balloon counterpulsation therapy

BACKGROUND

Intraaortic balloon pump (IABP) therapy is a widely used method of circulatory support. Based on frequent findings of balloon malposition with visceral arterial compromise on computerized tomographic (CT) imaging studies, we conducted a systematic review of cardiac surgical IABP patients with available CT scans to determine reasons, incidence, and clinical relevance of malposition.

METHODS AND RESULTS

From January 2007 to March 2009, a total of 621 of 7756 cardiac surgical patients (8.0%) received perioperative IABP support, of whom 63 (10.1%) received a thoracoabdominal CT scan during IABP support. Proximal and distal balloon positions were analyzed. The anatomic distance from the left subclavian artery to celiac trunk and aortic transverse diameter were measured in all patients and compared with implanted balloon dimensions. Mean age was 67.1±11.9 years; 33.3% were female, and height was 169±9 cm. Based on radiography, proximal balloon position was correct in 96.8% but only appropriate in 38.1% based on CT. In 61 of 63 patients, compromise of at least 1 visceral artery was found: celiac trunk, 96.8%; superior mesenteric artery, 87.3%; and renal arteries, 66.7%. Left subclavian artery to celiac trunk distance was 241±23 mm, and balloon length was 248±17 mm and corresponded to an anatomic to balloon length mismatch in 68.2%. Spinal deformations were found in 42.9%. Laparotomy for mesenteric ischemia was required in 23.8%. Hospital mortality rate was 60.3%.

CONCLUSIONS

IABP malposition was commonly identified by CT. Reasons included incorrect proximal balloon position as well as an anatomic-to-balloon length mismatch. Thus, shorter than recommended balloon sizes and better positioning strategies had to be considered.

A clinical score to predict the need for intraaortic balloon pump in patients undergoing coronary artery bypass grafting

BACKGROUND

There is no accepted consensus on the definition of high-risk patients who may benefit from the use of intraaortic balloon pump (IABP) in coronary artery bypass grafting (CABG). The aim of this study was to develop a risk model to identify high-risk patients and predict the need for IABP insertion during CABG.

METHODS

From April 1996 to December 2006, 8,872 consecutive patients underwent isolated CABG; of these 182 patients (2.1%) received intraoperative or postoperative IABP. The scoring risk model was developed in 4,575 patients (derivation dataset) and validated on the remaining patients (validation dataset). Predictive accuracy was evaluated by the area under the receiver operating characteristic curve.

RESULTS

Mortality was 1% in the entire cohort and 18.7% (22 patients) in the group which received IABP. Multivariable analysis showed that age greater than 70 years, moderate and poor left ventricular dysfunction, previous cardiac surgery, emergency operation, left main disease, Canadian Cardiovascular Society 3-4 class, and recent myocardial infarction were independent risk factors for the need of IABP insertion. Three risk groups were identified. The observed probability of receiving IABP and mortality in the validation dataset was 36.4% and 10% in the high-risk group (score >14), 10.9% and 2.8% in the medium-risk group (score 7 to 13), and 1.7% and 0.7% in the low-risk group (score 0 to 6).

CONCLUSIONS

This simple clinical risk model based on preoperative clinical data can be used to identify high-risk patients who may benefit from elective insertion of IABP during CABG.

The need for intra aortic balloon pump support following open heart surgery: risk analysis and outcome

Background

The early and intermediate outcome of patients requiring intraaortic balloon pump (IABP) was studied in a cohort of 2697 adult cardiac surgical patients.

Methods

136 patients requiring IABP (5.04%) support analysed over a 4 year period. Prospective data collection, obtained.

Results

The overall operative mortality was 35.3%. The "operation specific" mortality was higher on the Valve population.

The mortality (%) as per time of balloon insertion was: Preoperative 18.2, Intraopeartive 33.3, postoperative 58.3 (p < 0.05).

The incremental risk factors for death were: Female gender (Odds Ratio (OR) = 3.87 with Confidence Intervals (CI) = 1.3-11.6), Smoking (OR = 4.88, CI = 1.23- 19.37), Preoperative Creatinine>120 (OR = 3.3, CI = 1.14-9.7), Cross Clamp time>80 min (OR = 4.16, CI = 1.73-9.98) and IABP insertion postoperatively (OR = 19.19, CI = 3.16-116.47).

The incremental risk factors for the development of complications were: Poor EF (OR = 3.16, CI = 0.87-11.52), Euroscore >7 (OR = 2.99, CI = 1.14-7.88), history of PVD (OR = 4.99, CI = 1.32-18.86).

The 5 years survival was 79.2% for the CABG population and 71.5% for the valve group. (Hazard ratio = 1.78, CI = 0.92-3.46).

Conclusions

IABP represents a safe option of supporting the failing heart. The need for IABP especially in a high risk Valve population is associated with early unfavourable outcome, however the positive mid term results further justify its use.

Postoperative Care of the Cardiac Surgical Patient

The subspecialty of interventional cardiology began in 1977. Since then, the discipline of interventional cardiology has matured rapidly, particularly with regards to ischemic heart disease. As a result, more patients are undergoing percutaneous catheter interventional therapy for ischemic heart disease and fewer patients are undergoing surgical myocardial revascularization. Those patients referred for surgical revascularization are generally older and have more complex problems. Furthermore, as the population ages more patients are referred to surgery for valvular heart disease. The result of these changes is a population of surgical patients older and sicker than previously treated.

Different characteristics of postoperative heart failure after surgery for aortic stenosis and coronary disease

OBJECTIVE

Postoperative heart failure (PHF) remains a major determinant of outcome after cardiac surgery. However, possible differences in characteristics of PHF after valve surgery and coronary surgery (CABG) have received little attention. Therefore, this issue was studied in patients undergoing aortic valve replacement (AVR) and CABG, respectively.

DESIGN

Three hundred and ninety-eight patients undergoing isolated AVR for aortic stenosis were compared with 398 patients, matched for age and sex, undergoing on-pump isolated CABG. Forty-five AVR and 47 CABG patients required treatment for PHF and these were studied in detail.

RESULTS

The AVR group had longer aortic cross-clamp time and higher rate of isolated right ventricular heart failure postoperatively. Myocardial ischemia during induction and perioperative myocardial infarction were more common in the CABG group. One-year mortality was 8.9% in the AVR group vs 25.5% in the CABG group (p = 0.05).

CONCLUSIONS

The incidence of PHF was similar in both groups but different characteristics were found. Isolated right ventricular failure and PHF precipitated by septicemia were more common in AVR patients. PHF was more clearly associated with myocardial ischemia and infarction in CABG patients, which could explain their less favorable survival.

Mortality in Open Heart Surgery with Intraaortic Balloon Pump Support

Mechanical circulatory assistance is frequently needed to support the failing heart. The aim of this study was to determine perioperative prognostic factors for hospital mortality in patients undergoing open heart surgery who required intraaortic balloon pump support. Between January 2002 and September 2006, 475 patients received an intraaortic balloon pump perioperatively. Hospital mortality was 21.89%. Risk factors for hospital death identified by multivariate logistic regression analysis were peripheral vascular disease, left main coronary artery disease, postoperative renal failure, postoperative cardiac arrest, and prolonged hospital stay. Minor and major intraaortic balloon pump-related complications were not significant in univariate and multivariate analysis; the incidence was 5.05%. It is suggested that the threshold for using balloon pump support is decreased in high-risk patients undergoing cardiac surgery.

Surgery for myocardial salvage in acute myocardial infarction and acute coronary syndromes

This article addresses the pathophysiology, the treatment options, and their rationale in the setting of life-threatening acute myocardial infarction and acute on chronic ischemia. Although biases may exist between cardiologists and surgeons, with this review, we hope to provide the reader with information that will shed light on the options that best suit the individual patient in a given set of circumstances.

Does Preoperative Ejection Fraction Predict Operative Mortality With Left Ventricular Restoration?

BACKGROUND

Ischemic cardiomyopathy and aneurysmal disease have been treated surgically with coronary artery bypass grafting in the past. The Dor technique for left ventricular restoration has demonstrated improved outcomes in patients with ischemic, akinetic ventricles. Our hypothesis was that even marked reduction in preoperative cardiac function (ejection fraction < .25) would not correlate with worse outcomes since the ventricle would be reshaped to improve function.

METHODS

A retrospective analysis was performed on all patients who had undergone ventricular restoration with the Dor procedure from January 1996 through September 2005. Patients with a preoperative ejection fraction (EF) < .25 and those with a EF > or = .25 were compared. All Society of Thoracic Surgeons database characteristics, mortality, length of stay (LOS), and need for intraaortic balloon pump (IABP) were analyzed.

RESULTS

The study included 89 patients (69 men, 20 women), 28 of whom had preoperative EFs < .25 (mean, .183 +/- .035; range, .08 to .25) and 61 had an EF > or = .25 (mean, .334 +/- .074; mean, .25 to .45). Overall operative mortality was 3.4% (3/89), with no statistically significant difference between the two groups (3.6% versus 3.3%). LOS was 7.4 +/- 3.6 days versus 8.9 +/- 15.6 days (p = NS), and need for IABP was 39.2% versus 8.1% (p < 0.05). Overall 5-year survival was 82%. Five-year survival in the EF < .25 cohort was 69.6% versus 88.3% in the EF > or = .25 cohort (p = 0.066).

CONCLUSIONS

Ventricular restoration with the Dor technique is a safe procedure. Marked reduction in ejection fraction is not a contraindication to left ventricular restoration; however, increased usage of IABP should be anticipated.

Postoperative cardiopulmonary thoracic imaging

An appreciation of the normal postoperative changes and complications following cardiac surgical procedures is essential when interpreting postoperative imaging studies. This article focuses on both the normal postoperative appearances and the imaging of complications following common cardiac surgical procedures. Irrespective of the specific nature of the surgery, certain common complications may occur, either from the surgery itself,the use of cardiac bypass, or the patient's underlying cardiac disorder. Postoperative imaging after specific thoracic cardiovascular surgeries is also discussed.

A multicenter comparison of intraaortic balloon pump utilization in isolated coronary artery bypass graft surgery

BACKGROUND

Single-center studies suggest substantial variation in intraaortic balloon pump (IABP) utilization. Our purpose is to examine IABP utilization over time and across medical centers.

METHODS

This was a prospective cohort of 29,961 consecutive patients undergoing isolated coronary artery bypass graft surgery, between 1995 and 2000, at 10 centers (eight in northern New England and two in Canada).

RESULTS

A total of 2,678 (8.9%) patients received an IABP. The rate of preoperative IABP insertion was 6.3%, and that of intra- or postoperative insertion was 2.6%. During the 6 years, IABP use increased from 7.0% to 10.3% (p(trend) <0.001). Preoperative IABP insertion increased from 5.4% to 7.8% (p(trend) < 0.001). There was no significant increase in intra-/postoperative IABP insertion 1.7% to 3.4% (p(trend) = 0.34). Adjustment for changes in patient and disease characteristics did not substantially alter these results. The rate of IABP use varied substantially by center, from 5.9% to 16.4% (p < 0.001). Adjustment for patient and disease characteristics resulted in variation from 4.8% to 12.8% across the 10 centers (p < 0.001). The adjusted rates of preoperative IABP insertion varied from 3.6% to 13.7% (p < 0.001), and the rates of intra-/postoperative IABP insertion ranged from 1.0% to 5.2% (p < 0.001). There was no significant correlation between the rates of preoperative and intra-/postoperative IABP use (r(s) = 0.085, p = 0.815).

CONCLUSIONS

During the 6 years, there was a 47% increase in the rate of IABP utilization. Even after adjustment, there was almost threefold variation in IABP use across centers. This variation likely reflects lack of consensus on the appropriate use of the IABP in CABG patients.

Appropriate timing of surgical intervention after transmural acute myocardial infarction

OBJECTIVE

Recommended timing of coronary revascularization after transmural acute myocardial infarction ranges from immediate surgical intervention to repair 4 weeks after infarction. Such wide variation has created a dilemma in the management of these patients. The objective of this study was to delineate the optimal timing of revascularization after transmural acute myocardial infarction in a large and contemporary patient population.

METHODS

We performed a retrospective multicenter analysis of 32,099 patients who underwent coronary artery bypass grafting as the sole procedure after transmural myocardial infarction between 1991 and 1996 by 179 surgeons at 33 hospitals in New York State.

RESULTS

Overall hospital mortality for all patients who underwent coronary revascularization with a history of transmural myocardial infarction was 3.3%. Hospital mortality decreased with increasing time interval between revascularization and transmural acute myocardial infarction: 14.2%, 13.8%, 7.9%, 3.8%, 2.9%, and 2.7% for less than 6 hours, 6 hours to 1 day, 1 to 3 days, 4 to 7 days, 7 to 14 days, and greater than 15 days, respectively. Multivariate analyses of 43 potential risk factors suggests that revascularization within 3 days of transmural acute myocardial infarction is independently associated with mortality.

CONCLUSIONS

Coronary revascularization within 3 days of a transmural acute myocardial infarction might be an added risk for mortality. In the absence of absolute indications for emergency surgical intervention, such as structural complications and ongoing ischemia, a 3-day waiting period before surgical revascularization should be considered.

The intraaortic balloon pump in cardiac surgery

The intraaortic balloon pump (IABP) has been used in cardiac operations since the late 1960s. Over the years, with refinements in technology, its use has expanded; the IABP is now the most commonly used mechanical assist device in cardiac operative procedures. This review provides an evaluation of evidence for the efficacy of IABP use in different clinical scenarios, using the American College of Cardiology/American Heart Association classification of evidence where appropriate. We evaluated complications and outcomes associated with IABP use, and attempted to draw conclusions regarding the use of the IABP in different clinical situations. We examined the trends and variation in utilization over time and across centers. We discussed the IABP in light of new cardiac assist devices and the changing patient population and management strategies. Lastly, we identified areas of future research.

Trends in intraaortic balloon counterpulsation complications and outcomes in cardiac surgery

BACKGROUND

As the proportion of high-risk patients for cardiac surgery increases, use of intraaortic balloon counterpulsation (IABC) has increased, especially in preoperative therapy. Although the efficacy and cost-effectiveness of IABC have been demonstrated, historically higher complication rates have dissuaded some practitioners from using IABC.

METHODS

This report describes IABC use in cardiac surgery, examines trends in complications over time, and compares outcomes in preoperative versus postoperative use in a single prospective worldwide registry over the past 3 years.

RESULTS

The frequency of IABC use appears to be increasing with time as the complication rates have dramatically fallen. The overall IABC-related complication rate was 6.5% (460/7,101), and the rate of major complications (requiring surgery or transfusion) was 2.1% (148/7,101). Hospital mortality was significantly lower in patients treated preoperatively with IABC compared with patients treated postoperatively (8.8% vs 28.2%, p < 0.0001), although this may be due to a selection bias in the postoperative group.

CONCLUSIONS

Preoperative IABC therapy leads to better patient outcomes in high-risk CABG patients. Improved IABC technology and better surveillance have led to increased use with lower complication rates. Although selection bias is inherent in retrospective studies, the Benchmark Counterpulsation Outcomes Registry outcomes are in close concordance to prospective randomized studies previously reported.

Prognosis After the Implantation of an Intra-Aortic Balloon Pump in Cardiac Surgery Calculated With a New Score

Background Over the past decade, the use of a ventricular-assist device (VAD) in patients with postcardiotomy cardiogenic shock has resulted in hospital discharge rates of 25% to 40% and is improving. Nevertheless, indications for and timing of the implantation of a VAD in patients who have received an intra-aortic balloon pump (IABP) remain unclear.

Methods and Results From July 1996 to March 2000, 391 patients with cardiac low-output syndrome who underwent open-heart surgery and had an IABP implanted were analyzed in a retrospective pilot study. The perioperative mortality was 34% (133 patients). Clinical parameters were analyzed 1 hour after IABP support began. Statistical multivariate analysis showed that patients with an adrenaline requirement higher than 0.5 μg · kg −1 · min −1 , a left atrial pressure >15 mm Hg, urine output <100 mL/h, and mixed venous saturation (S v O 2 ) <60% had poor outcomes. Using this data, we developed an IABP score (0 to 5 points) to predict survival early after IABP implantation in cardiac surgery. We evaluated our score by monitoring another 101 patients as a control group prospectively. Additionally, 210 patients who received coronary artery bypass grafting (CABG) exclusively were analyzed. All investigations confirmed the validity of the score.

Conclusions The IABP score can predict survival early after IABP implantation. In patients with a high IABP score, implantation of a VAD should be considered.

Mechanical Support After Cardiac Surgery

Mechanical circulatory support for low cardiac output after cariac surgery was first attempted in 1962. Since then, many ventricular assist devices have been developed and employed. The following is a discussion of the history, demographics, inications, and devices used for mechanical circulatory suport in this setting. lntra-aortic balloon pulsation, pulsatile verus non-pulsatile flow, volume bypass, roller and centrifugal pumps, extracorporeal membrane oxygenation, and imlantable devices are reviewed. Early postoperative care, reovery and weaning from mechanical circulatory support, and the special issues that relate to biventricular failure and control of right-sided ventricular function, as well as anticoagulation, and sepsis are addressed.

Coronary artery bypass grafting in patients with severe left ventricular dysfunction: a prospective randomized study on the timing of perioperative intraaortic balloon pump support

In this prospective trial the results of preoperative and intraoperative IABP in coronary artery bypass graft (CABG) patients with low left ventricular ejection fraction (LVEF) were compared. Sixty CABG patients with preoperative LVEF < or = 0.30 were enrolled: in group A patients (n=30) IABP was started within 2 hours preoperatively; in group B (n=30) it was instituted intraoperatively before weaning from cardiopulmonary bypass. Cardiac performance was assessed through Swan-Ganz catheter monitoring and daily echocardiography. Hospital survival, length of IABP support, intubation, ICU and hospital stay, need for postoperative inotropic drugs and incidence of myocardial infarction were compared between the two groups. Survival in group A patients proved significantly higher (P=0.047). Cardiac performance after myocardial revascularization improved in both groups with significantly better outcomes in group A patients (P<0.001). Doses of inotropic drugs (dobutamine, enoximone) were lower in group A (P=0.001; P=0.004) and duration shorter (P<0.001; P<0.001). No major IABP-related complication was observed.

Intra-aortic balloon counterpulsation: outcome in cardiac surgical patients

OBJECTIVE

To identify the major determinants of survival and nonsurvival for patients in need of intra-aortic balloon pump (IABP) support after cardiac surgery and to define the role of ventilator-associated pneumonia.

DESIGN

Retrospective study.

SETTING

University and general hospital.

PARTICIPANTS

A total of 105 consecutive patients undergoing cardiac surgery requiring IABP support and prolonged mechanical ventilation for >24 hours.

INTERVENTION

All patients were assigned into 1 of 2 groups: survival (n = 69) and nonsurvival (n = 36).

MEASUREMENTS AND MAIN RESULTS

Differences between the survival and nonsurvival groups were tested with the Student's t-test, chi-square test, and frequency analysis. The overall survival rate was 65.7%. Nonsurvivors (34.3%) had higher rates of acute myocardial infarction (27.7% v 4.3%; p < 0.002), Canadian Cardiovascular Society functional class III and IV (44.4% and 13.8%; p < 0.001), and depressed left ventricular ejection fraction (31.3 +/- 6.4% v 42.4 +/- 7.2%; p < 0.001). The nonsurvival group had longer duration of cardiopulmonary bypass (165 +/- 74.3 minutes v 135 +/- 36 minutes; p < 0.006) and aortic occlusion (81.8 +/- 9 minutes v 68.6 +/- 25.7 minutes; p < 0.004). In the nonsurvival group, 21 patients were not weaned from the IABP, and 15 patients were weaned from the IABP but died from renal failure (26.6%), multiorgan failure (13.3%), infection, and respiratory failure (66.6%). In the nonsurvival group, mechanical ventilation time was longer in patients weaned from the IABP.

CONCLUSION

These data suggest that for patients not weaned from the IABP, the major determinants of death are low cardiac output (33.3%) and multiorgan failure (47.6%). Patients with a left ventricular ejection fraction of <30% have a poorer outcome. In patients weaned from the IABP, ventilator-associated pneumonia (66.6%) was the major cause of death.

Intraaortic balloon pump therapy facilitates posterior vessel off-pump coronary artery bypass grafting in high-risk patients

BACKGROUND

Displacement of the heart to expose posterior vessels during coronary artery bypass grafting (CABG) without cardiopulmonary bypass (off-pump CABG, or OPCAB) may impair cardiac function. We used the intraaortic balloon pump (IABP) preoperatively to reduce operative risk and to facilitate posterior vessel OPCAB in high-risk patients with left main coronary artery disease (> 75% stenosis), intractable resting angina, postinfarction angina, left ventricular dysfunction (ejection fraction < 35%), or unstable angina.

METHODS

One hundred and forty-two consecutive patients who underwent multivessel OPCAB including posterior vessel revascularization were studied prospectively. The patients were divided into group I (n = 57), which received preoperative or intraoperative IABP, and group II (n = 85), which did not receive IABP. In group I, there were 34 patients with left main coronary artery disease, 24 patients with intractable resting angina, 8 patients with left ventricular dysfunction, 5 patients with postinfarction angina, and 40 patients with unstable angina. Seven patients received intraoperative IABP support owing to hemodynamic instability during OPCAB.

RESULTS

There was no operative mortality in group I and 1 death in group II. The average number of distal anastomoses was not different between group I and group II (3.4 +/- 0.9 versus 3.5 +/- 0.9, p = not significant). There were no significant differences in the number of posterior vessel anastomoses per patient. There were no differences in ventilator support time, length of stay in the intensive care unit, hospital stay, and morbidity between the two groups. There was one IABP-related complication in group I.

CONCLUSIONS

IABP therapy facilitates posterior vessel OPCAB in high-risk patients, and surgical results are comparable with those in lower-risk patients.

High lactate predicts the failure of intraaortic balloon pumping after cardiac surgery

BACKGROUND

Despite the use of intraaortic balloon pump (IABP) support in complex cardiac surgical patients, morbidity and mortality rates are high. More advanced mechanical cardiovascular support should be considered in those patients who are highly likely to die despite IABP support. We sought to identify early, readily available prognostic markers for patients receiving IABP support.

METHODS

A retrospective analysis was performed on 39 patients requiring IABP support following cardiac surgery for more than 2 years. The accuracy and predictive ability of multiple potential markers of mortality were statistically assessed.

RESULTS

Sixty-seven percent of the patients were successfully weaned from IABP support and 46% survived to hospital discharge. Serious complications occurred in 13% of patients. Serum lactate more than 10 mmol/L in the first 8 hours of IABP support predicted a 100% mortality. Base deficit more than 10 mmol/L, mean arterial pressure less than 60 mm Hg, urine output less than 30 mls/h for 2 hours, and dose of epinephrine or norepinephrine more than 10 microg/min were other highly predictive prognostic markers.

CONCLUSIONS

Morbidity and mortality rates remain high despite IABP support following cardiac surgery. Mortality can be predicted by the presence of elevated serum lactate, elevated base deficit, hypotension, oliguria and large vasopressor doses, any of which should prompt appropriate consideration as to other mechanical cardiovascular support.

Optimal timing of revascularization: transmural versus nontransmural acute myocardial infarction

BACKGROUND

Higher mortality for emergency coronary artery bypass grafting (CABG) after an acute myocardial infarction (AMI) is well established. Whether it applies to both transmural and nontransmural AMI is unclear. This information may have different therapeutic implications for each cohort of patients.

METHODS

A retrospective multicenter analysis of 44,365 patients who underwent CABG after myocardial infarction between 1993 and 1996 by 179 surgeons at 32 hospitals in New York State was performed.

RESULTS

Overall hospital mortality for all patients with or without AMI was 2.5% versus 3.1% for patients who underwent CABG with history of myocardial infarction. Hospital mortality decreased with increasing time interval between CABG and AMI; 11.8%, 9.5%, and 2.8% (p < 0.001 for all values) for less than 6 hours, 6 hours to 1 day, and greater than 1 day, respectively. Patients with transmural and nontransmural AMI had identical mortality of 3.1%. However, different patterns emerged when comparing these two groups of patients with respect to time of operation. Mortality was higher in the transmural group if CABG was performed within 7 days after AMI. Multivariate analysis confirmed that CABG within 1 day and 6 hours of AMI are independent risk factors for mortality in the transmural and nontransmural groups, respectively.

CONCLUSIONS

Early operation after transmural AMI has a significantly higher risk, and surgeons should be prepared to provide aggressive cardiac support including left ventricular assist devices in this ailing population. Waiting in some may be warranted.

Elective intraaortic balloon counterpulsation for high-risk off-pump coronary artery bypass operations

BACKGROUND

Dislocations of the heart required for exposure and construction of distal anastomoses often produce hemodynamic instability when performing coronary artery revascularization without using cardiopulmonary perfusion (OPCAB). We report our early experience with elective intraaortic balloon counterpulsation (IABP) to enable and facilitate selected high-risk patients to undergo OPCAB.

METHODS

Sixteen high-risk patients undergoing multivessel OPCAB using elective IABP are reported. The patients were believed to be at increased risk because of the presence of severe proximal multivessel coronary artery obstruction, ventricular dysfunction, recent acute myocardial infarction, cardiomegaly-cardiomyopathy, and documented cerebral vascular disease. The presence of significant comorbid disease also made the avoidance of cardiopulmonary bypass desirable, if at all possible, in all patients.

RESULTS

The IABP appeared to facilitate the intraoperative management of our series of patients. This was evidenced by improved hemodynamic stability and virtual elimination of the need for inotropic support during the dislocations of the heart needed for exposure and construction of distal anastomoses. There were no complications related to use of IABP. There was one death.

CONCLUSIONS

We believe this strategy to use IABP selectively can allow surgeons to safely extend the benefits of OPCAB procedures to high-risk patients and avoid dangerous hemodynamic instability that otherwise, often occurs.

Predictors of survival 1 hour after implantation of an intra-aortic balloon pump in cardiac surgery

From July 1996 to March 2000, 391 patients with intraoperative cardiac low-output syndrome who underwent surgery with heart-lung bypass and had an intra-aortic balloon pump (IABP) implanted were analyzed in a prospective study. Of these 391 patients, 153 (39%) were operated on in an emergency situation, and 238 (61%) patients had elective surgeries. The perioperative mortality was 34% (133 patients). Clinical parameters were analyzed 1 hour after IABP support began. Statistical multivariate analysis showed that patients with an adrenaline requirement higher than 0.5 microg/kg/min, a left atrial pressure higher than 15 mmHg, output of less than 100 mL/hour, and mixed venous saturation (SvQ2) of less than 60% had poor outcomes. Using this data, we developed an IABP score to predict survival early after IABP implantation in cardiac surgery. We conclude that the success or failure of perioperative IABP support can be predicted early after implantation of the balloon pump. In patients with low-output syndrome despite IABP support, implantation of a ventricular assist system should be considered.

Ascending versus descending aortic balloon pumping: organ and myocardial perfusion during ischemia

BACKGROUND

The ICS-Supracor (Abiomed, Danvers, MA) is a preshaped ascending aorta balloon pump. We compared the effects of this catheter with the classical descending intraaortic balloon pump (IABP). The study focused on hemodynamic effects, myocardial blood flow in normal and ischemic regions, cerebral perfusion, and peripheral organ perfusion.

METHODS

We placed a stenosis on the lateral branch of the coronary artery to reduce flow 50% (sheep). Measurements included hemodynamic changes, myocardial blood flow, and organ flow (colored microspheres) at baseline, after stenosis, during IABP support, and during ICS support.

RESULTS

Counterpulsation with the ICS led to a significantly higher peak diastolic aortic augmentation than with the IABP (IABP, 99 +/- 14 mm Hg; ICS, 140 +/- 29 mm Hg; p = 0.003). There was no significant change in cerebral perfusion or peripheral organ perfusion. Myocardial blood perfusion was significantly increased by the IABP as well as the ICS. This effect was seen in ischemic and nonischemic regions (subendocardial and subepicardial). The ICS improved myocardial blood flow significantly more than the IABP (IABP, 0.65 +/- 0.1 mL/min/g; ICS, 0.94 +/- 0.06 mL/min/g; p = 0.0005).

CONCLUSIONS

The ICS increases myocardial blood flow in ischemic regions significantly more than the IABP, without impairment of cerebral flow. Assessment of vascular complications, peripherally and in the ascending aorta, has to await results of clinical trials.

Economic impact of preoperative intraaortic balloon pump therapy in high-risk coronary patients

BACKGROUND

The efficacy of preoperative intraaortic balloon pump therapy in high-risk coronary patients has been demonstrated earlier.

METHODS

This study investigates the economic aspect by a detailed cost analysis of pooled information from two previously published randomized studies and 144 consecutive low-risk coronary artery bypass graft operations. Costs for patients receiving preoperative intraaortic balloon pump therapy before aortic cross-clamping (n = 62) were compared to those in a control group (n = 50). Detailed cost analysis was based on data provided by the hospital finance department.

RESULTS

The total hospital costs were as follows: low-risk coronary artery bypass graft operations cost 35,335+/-1,694 Swiss francs ($23,400+/-$1,121); high-risk coronary artery bypass graft without preoperative intraaortic balloon pump therapy cost 65,892+/-31,719 Swiss francs ($43,637+/-$21,006); and high risk coronary artery bypass graft with preoperative intraaortic balloon pump therapy cost 41,948+/-10,379 Swiss francs ($27,780+/-$6,874) (p = 0.0015). There were no significant differences in average cost among the preoperative intraaortic balloon pump therapy subgroups.

CONCLUSIONS

Preoperative intraaortic balloon pump therapy in high risk coronary patients is significantly cost-beneficial, With an average saving of 24,000 Swiss francs ($16,000) on the total hospital cost, a 36% cost reduction.

The intra-aortic cannula pump: A novel assist device for the acutely failing heart

OBJECTIVE

The intra-aortic cannula pump is a catheter pump designed to support the acutely failing heart. It expels blood from the left ventricle into the ascending aorta in a pulsatile flow pattern. The aim of the study was to analyze the hemodynamic performance of this new intracardiac support system in acute heart failure.

METHODS

A 24F cannula was studied in a series of 16 sheep. Hemodynamic changes were assessed in the nonfailing, the moderately failing, and the severely failing heart. Heart failure was induced by an injection of microspheres into the left anterior descending coronary artery. The cannula was inserted through the aortic arch and introduced through the aortic valve into the left ventricle.

RESULTS

Cannula insertion was feasible in all animals. Flow through the intra-aortic cannula flow was increased to a maximum of 3 L/min. No hemodynamic changes were observed in the nonfailing heart. A significant increase in cardiac output was observed in the moderately and severely reduced left ventricle (2.67 +/- 0.7 L to 3.51 +/- 0.83 L; P =.001; and 1.18 +/- 0.77 L to 2.43 +/- 0.44 L; P =.001, respectively). A drop in left atrial pressure was achieved in moderate and severe heart failure (14.1 +/- 5.93 mm Hg to 9.71 +/- 2.63 mm Hg; P =.0001; and 23 +/- 7.16 mm Hg to 11.2 +/- 2.55 mm Hg; P = 0.0001, respectively). Systolic and diastolic systemic blood pressures increased in the severely failing heart (57.3 +/- 12.8 mm Hg to 75.4 +/- 11.2 mm Hg; P =.0001; and 35.6 +/- 8.2 mm Hg to 60 +/- 14.3 mm Hg; P =.0006, respectively).

CONCLUSIONS

Hemodynamic data demonstrate the beneficial effects of the intra-aortic cannula pump in moderate and severe heart failure. The intra-aortic cannula pump represents a new modality for the treatment of acute heart failure.

Chronic aortic counterpulsation with latissimus dorsi in heart failure: clinical follow-up

BACKGROUND

Dynamic aortomyoplasty is an alternative technique to heart transplantation. The goal of our study was to evaluate the benefits of aortic counterpulsation obtained by dynamic thoracic aortomyoplasty in patients with heart failure refractory to pharmacologic treatment and contraindications to heart transplant or cardiomyoplasty.

METHODS

In this study we compared preoperative and postoperative data from five out of six carefully selected patients who were treated with dynamic thoracic aortomyoplasty. This surgical technique wraps the right latissimus dorsi muscle flap around the ascending aorta. This muscle flap was electrically stimulated during diastole, following a muscle-conditioning protocol, to obtain diastolic augmentation. At the 6-month follow-up period we evaluated, invasively and noninvasively, the hemodynamic and clinical effects of aortomyoplasty.

RESULTS

We observed a significant decrease in the number of hospitalizations (P = 0.01), NYHA functional class (P = 0.01), cardiothoracic ratio (P = 0.02), right ventricular diameter (P = 0.03), left atrial diameter (P = 0.04), and pulmonary artery systolic pressure (P = 0.04); and a significant increase in the 6-minute walking test (P = 0.01), cardiac index (P = 0.04), noninvasive evaluation of diastolic augmentation (P = 0.01), left ventricular shortening fraction (P = 0.01), and radioisotopic left ventricular ejection fraction (P = 0.02). We also found a nonsignificant decrease in the left ventricular diameter (P = 0.08) and wedge pressure (P = 0.19); and a nonsignificant increase in peak oxygen consumption (P = 0.13).

CONCLUSIONS

Dynamic thoracic aortomyoplasty in heart failure resulted in an important improvement of hemodynamic parameters, heart functional data, and clinical functional class, when comparing preoperative data with the 6-month follow-up data.