Intra-aortic balloon counterpulsation - basic principles and clinical evidence

Hemodynamic effects of a dielectric elastomer augmented aorta on aortic wave intensity: An in-vivo study

Dielectric elastomer actuator augmented aorta (DEA) represents a novel approach with high potential for assisting a failing heart. The soft tubular device replaces a section of the aorta and increases its diameter when activated. The hemodynamic interaction between the DEA and the left ventricle (LV) has not been investigated with wave intensity (WI) analysis before. The objective of this study is to investigate the hemodynamic effects of the DEA on the aortic WI pattern. WI was calculated from aortic pressure and flow measured in-vivo in the descending aorta of two pigs implanted with DEAs. The DEAs were tested for different actuation phase shifts (PS). The DEA generated two decompression waves (traveling upstream and downstream of the device) at activation followed by two compression waves at deactivation. Depending on the PS, the end-diastolic pressure (EDP) decreased by 7% (or increased by 5-6%). The average early diastolic pressure augmentation (Pdia¯) increased by 2% (or decreased by 2-3%). The hydraulic work (WH) measured in the aorta decreased by 2% (or increased by 5%). The DEA-generated waves interfered with the LV-generated waves, and the timing of the waves affected the hemodynamic effect of the device. For the best actuation timing the upstream decompression wave arrived just before aortic valve opening and the upstream compression wave arrived just before aortic valve closure leading to a decreased EDP, an increased Pdia¯ and a reduced.WH.

Comparison of Left Ventricular Global Longitudinal Strain with Ejection Fraction as a Predictor for Peri-operative IABP Insertion in Patients Undergoing Off-Pump Coronary Artery Bypass Grafting: A Pilot Study

Background

Prophylactic use of intra-aortic balloon pump (IABP) mainly depends on left ventricular (LV) systolic function. Global longitudinal strain (GLS) is a robust prognostic parameter for LV strain. It has proved to be more sensitive than LV ejection fraction (EF) as a measure of LV systolic function and is a strong predictor of outcome.

Aim

To determine whether GLS can be used as a reliable marker and its cut-off value for IABP insertion in patients undergoing elective off-pump coronary artery bypass grafting (OPCABG).

Settings and Design

A prospective observational clinical study which included 100 adult patients scheduled for elective OPCABG.

Materials and Methods

Two-dimensional (2D) speckle tracking echocardiography (STE)-estimated GLS was computed and compared with LV EF measured by three dimensional (3D) echocardiography for the insertion of IABP. The intensive care unit (ICU) parameters were correlated with echocardiographic parameters to predict early post-operative outcome.

Results

IABP insertion correlates better with GLS (post-revascularization > pre-revascularization) than with 3D LV EF. Receiver operating characteristic (ROC) curve analysis revealed the highest area under the curve (AUC, 0.972) with a cut-off value of > -9.8% for GLS compared to 3D LV EF (AUC, 0.938) with a cut-off value of ≤ 44%. ICU parameters show better correlation with E/e'> GLS > WMSI than 3D LV EF.

Conclusion

GLS is a better predictor of IABP insertion compared to 3D LV EF in patients undergoing OPCABG.

Positive association between stress hyperglycemia ratio and pulmonary infection in patients with ST-segment elevation myocardial infarction undergoing percutaneous coronary intervention

BACKGROUND

Previous studies have shown that the stress hyperglycemia ratio (SHR), a parameter of relative stress-induced hyperglycemia, is an excellent predictive factor for all-cause mortality and major adverse cardiovascular events (MACEs) among patients with ST-segment elevation myocardial infarction (STEMI). However, its association with pulmonary infection in patients with STEMI during hospitalization remains unclear.

METHODS

Patients with STEMI undergoing percutaneous coronary intervention (PCI) were consecutively enrolled from 2010 to 2020. The primary endpoint was the occurrence of pulmonary infection during hospitalization, and the secondary endpoint was in-hospital MACEs, composed of all-cause mortality, stroke, target vessel revascularization, or recurrent myocardial infarction.

RESULTS

A total of 2,841 patients were finally included, with 323 (11.4%) developing pulmonary infection and 165 (5.8%) developing in-hospital MACEs. The patients were divided into three groups according to SHR tertiles. A higher SHR was associated with a higher rate of pulmonary infection during hospitalization (8.1%, 9.9%, and 18.0%, P < 0.001) and in-hospital MACEs (3.7%, 5.1%, and 8.6%, P < 0.001). Multivariate logistic regression analysis demonstrated that SHR was significantly associated with the risk of pulmonary infection during hospitalization (odds ratio [OR] = 1.46, 95% confidence interval [CI] 1.06-2.02, P = 0.021) and in-hospital MACEs (OR = 1.67, 95% CI 1.17-2.39, P = 0.005) after adjusting for potential confounding factors. The cubic spline models demonstrated no significant non-linear relationship between SHR and pulmonary infection (P = 0.210) and MACEs (P = 0.743). In receiver operating characteristic curve, the best cutoff value of SHR for pulmonary infection was 1.073.

CONCLUSIONS

The SHR is independently associated with the risk of pulmonary infection during hospitalization and in-hospital MACEs for patients with STEMI undergoing PCI.

A novel soft cardiac assist device based on a dielectric elastomer augmented aorta: An in vivo study

Although heart transplant is the preferred solution for patients suffering from heart failures, cardiac assist devices remain key substitute therapies. Among them, aortic augmentation using dielectric elastomer actuators (DEAs) might be an alternative technological application for the future. The electrically driven actuator does not require bulky pneumatic elements (such as conventional intra-aortic balloon pumps) and conforms tightly to the aorta thanks to the manufacturing method presented here. In this study, the proposed DEA-based device replaces a section of the aorta and acts as a counterpulsation device. The feasibility and validation of in vivo implantation of the device into the descending aorta in a porcine model, and the level of support provided to the heart are investigated. Additionally, the influence of the activation profile and delay compared to the start of systole is studied. We demonstrate that an activation of the DEA just before the start of systole (30 ms at 100 bpm) and deactivation just after the start of diastole (0-30 ms) leads to an optimal assistance of the heart with a maximum energy provided by the DEA. The end-diastolic and left ventricular pressures were lowered by up to 5% and 1%, respectively, compared to baseline. The early diastolic pressure was augmented in average by up to 2%.

The Predictive Value of N-Terminal Probrain Natriuretic Peptide for Infection in Patients With Acute Myocardial Infarction

Background: Infections increase the risk of poor outcomes in patients with ST-elevation myocardial infarction (STEMI) undergoing percutaneous coronary intervention (PCI). However, predicting patients at a high risk of developing infection remains unclear. Moreover, the value of N-terminal probrain natriuretic peptide (NT-proBNP) for predicting infection is still unknown. Thus, we aimed to assess the relationship between NT-proBNP and the following development of infection, and clinical adverse outcomes in patients with STEMI undergoing PCI.

Methods: STEMI patients undergoing PCI were consecutively enrolled from January 2010 to July 2016 and divided into groups according to baseline NT-proBNP levels: tertiles T1 (<988 pg/mL), T2 (988–3520 pg/mL), and T3 (≥3520 pg/mL). The primary endpoint was infection during hospitalization.

Results: A total of 182 (27%) patients developed in-hospital infection. The incidence of infection increased from T1 to T3 (10.5, 17.7, and 54.5%, P < 0.001). NT-proBNP was an independent risk factor (adjusted odds ratio = 1.39, 95% confidence interval (CI) = 1.12–1.73, P = 0.003) and presented accurately predicting infection (area under curve = 0.774). Multivariate cox analysis showed that NT-proBNP was a significant risk factor for major adverse clinical events (MACE) at follow-up (adjusted HR = 1.92, 95% CI = 1.61–2.29, P < 0.001).

Conclusion: The baseline NT-proBNP level has a good predictive value for infection and MACE in STEMI patients undergoing PCI.

Factors Associated with the Prognosis of Patients with Acute Myocardial Infarction and Cardiogenic Shock

BACKGROUND Patients with acute myocardial infarction (AMI) complicated by cardiogenic shock (CS) usually have high mortality. This study aimed to identify factors related to the short-term survival of patients with AMI and CS treated by percutaneous coronary intervention (PCI) under intra-aortic balloon pump (IABP) support. MATERIAL AND METHODS This retrospective study included consecutive patients with AMI and CS treated with PCI under IABP support. Clinical characteristics, including the infarct-related artery, lesion number, aspiration catheter usage, conventional or delayed stenting, and thrombolysis in myocardial infarction (TIMI) flow grade before and after PCI, were collected. Patients were followed up postoperatively for 30 days. Multivariate logistic regression was used to identify factors associated with the 30-day mortality. RESULTS There were marked differences between the nonsurvival group (n=49) and the survival group (n=92) in the no-reflow after surgery (49.0% vs 14.1%, P<0.001), postoperative TIMI grade 3 flow (65.3% vs 91.3%, P<0.001), and delayed stent implantation (18.4% vs 37.0%, P=0.022). Factors associated with 30-day mortality were postoperative TIMI grade 3 flow (odds ratio [OR]: 0.227; 95% confidence interval [CI]: 0.076-0.678; P=0.008), delayed stent implantation (OR: 0.371; 95% CI: 0.139-0.988; P=0.047), and intraoperative no-reflow (OR: 2.737; 95% CI: 1.084-6.911; P=0.033). CONCLUSIONS For patients with AMI complicated by CS treated with emergent PCI under IABP support, prevention of no-reflow during surgery by delayed stent implantation can reduce postoperative 30-day mortality in selected cases.

Feasibility of a Dielectric Elastomer Augmented Aorta

Although heart transplantation is a gold standard for severe heart failure, there is a need for alternative effective therapies. A dielectric-elastomer aorta is used to augment the physiological role of the aorta in the human circulatory system. To this end, the authors developed a tubular dielectric elastomer actuator (DEA) able to assist the heart by easing the deformation of the aorta in the systole and by increasing its recoil force in the diastole. In vitro experiments using a pulsatile flow-loop, replicating human physiological flow and pressure conditions, show a reduction of 5.5% (47 mJ per cycle) of the heart energy with this device. Here, the controlled stiffness of the DEA graft, which is usually difficult to exploit for actuators, is perfectly matching the assistance principle. At the same time, the physiological aortic pressure is exploited to offer a prestretch to the DEA which otherwise would require an additional bulky pre-stretching system to reach high performances.

Patient and Device Selection for Hemodynamic Support in High-Risk Percutaneous Coronary Intervention

Coronary artery disease continues to advance resulting in the development of high-risk percutaneous interventions. This includes treatment of patients with multivessel disease, unprotected left main, acute myocardial infarction complicated by cardiogenic shock, and depressed left ventricular ejection fraction. As a result, mechanical circulatory support devices have evolved but require an understanding of patient hemodynamics, device mechanics, and access management. Trial data regarding device selection are limited by inclusion of cardiogenic shock patients, and observational studies are conflicted by selection bias, site familiarity with devices, and complication management; therefore, clinical judgment is required to treat high-risk patients appropriately.

Muscle-Powered Counterpulsation for Untethered, Non-Blood-Contacting Cardiac Support: A Path to Destination Therapy

Conventional long-term ventricular assist devices continue to be extremely problematic due to infections caused by percutaneous drivelines and thrombotic events associated with the use of blood-contacting surfaces. Here we describe a muscle-powered cardiac assist device that avoids both these problems by using an internal muscle energy converter to drive a non-blood-contacting extra-aortic balloon pump. The technology was developed previously in this lab and operates by converting the contractile energy of the latissimus dorsi muscle into hydraulic power that can be used, in principle, to drive any blood pump amenable to pulsatile actuation. The two main advantages of this implantable power source are that it 1) significantly reduces infection risk by avoiding a constant skin wound, and 2) improves patient quality-of-life by eliminating all external hardware components. The counterpulsatile balloon pumps, which compress the external surface of the ascending aorta during the diastolic phase of the cardiac cycle, offer another critical advantage in the setting of long-term circulatory support in that they increase cardiac output and improve coronary perfusion without touching the blood. The goal of this work is to combine these two technologies into a single circulatory support system that eliminates driveline complications and avoids surface-mediated thromboembolic events, thereby providing a safe, tether-free means to support the failing heart over extended - or even indefinite - periods of time.

Imaging of Cardiac Support Devices

Patients hospitalized in the intensive care unit (ICU) often have multiple support lines and devices that need routine imaging evaluation by radiologists. In patients with cardiogenic shock or depressed cardiac function, mechanical circulation support devices are used in combination with medical therapies to improve patient outcomes and sometimes can stabilize patients for surgical intervention. This article discusses some of the more commonly encountered mechanical circulation devices seen in ICU patients, including intra-aortic balloon pumps, Impella devices, extracorporeal membrane oxygenation cannulas, and ventricular assist devices. Normal appearance and commonly encountered device-related complications that can be diagnosed on imaging are reviewed.

A New 35-mm Short Intra-aortic Balloon Catheter: A Suitable Option Also for Non-Small-Sized Patients?

OBJECTIVE

Visceral ischemia can be a potentially life-threatening complication of intra-aortic balloon pump (IABP) support. A shorter IABP catheter might lead to a reduction of visceral complications. In this animal study, we evaluate the effects of a 35-mL short catheter in comparison with a 40-mL standard-sized catheter.

METHODS

Eighteen healthy swine underwent 120-minute ligation of the left anterior descending coronary artery followed by 6 hours of reperfusion being supported by either a short IABP catheter (short group) (n = 6) or a long IABP catheter (long group) (n = 6) or with no assistance (controls) (n = 6). Hemodynamics, visceral and coronary flows, as well as biochemical markers were evaluated throughout the different phases of the protocol.

RESULTS

Mesenteric flows increased significantly at reperfusion (P < 0.001 both) remaining constant afterward (all, P > 0.05) in the short group, while remaining significantly lower in the long group at the start of reperfusion, remaining constantly lower than the short group and controls (P < 0.001 vs short, P < 0.003 vs controls). In both long and short groups, catheters improved renal flows at reperfusion (P < 0.001 both) without any further variation (P > 0.05). In the short group, the flows were higher during the whole of reperfusion (all, P < 0.05). Intra-aortic balloon pump support improved hemodynamic indices and coronary blood flows during reperfusion to a similar extent in both the small and the long group (P > 0.05).

CONCLUSIONS

The short IABP catheter proved to be as effective as the standard-sized catheter in supporting hemodynamics and coronary circulation. Furthermore, it even improves visceral flows in comparison with conventional IABP catheters.

IABP: history-evolution-pathophysiology-indications: what we need to know

Treatment with the intraaortic balloon pump (IABP) is the most common form of mechanical support for the failing heart. Augmentation of diastolic pressure during balloon inflation contributes to the coronary circulation and the presystolic deflation of the balloon reduces the resistance to systolic output. Consequently, the myocardial work is reduced. The overall effect of the IABP therapy is an increase in the myocardial oxygen supply/demand ratio and thus in endocardial viability.

This is an overall synopsis of what we need to know regarding IABP. Furthermore, this review article attempts to systematically delineate the pathophysiology linked with the hemodynamic consequences of IABP therapy. The authors also look at the future of the use of the balloon pump and conclude that the positive multi-systemic hemodynamic regulation during IABP treatment should further justify its use.

Intra-aortic balloon pump may grant no benefit to improve the mortality of patients with acute myocardial infarction in short and long term: an updated meta-analysis

Intra-aortic balloon pump (IABP) has been extensively used in clinical practice as a circulatory-assist device. However, current literature demonstrated significantly varied indications for IABP application and prognosis.The objective of the study was to assess the potential benefits or risks of IABP treatment for acute myocardial infarction (AMI) complicated with or without cardiogenic shock.MEDLINE and EMBASE database were systematically searched until November 2014, using the terms as follows: IABP, IABC (intra-aortic balloon counterpulsation), AMI, heart infarction, coronary artery disease, ischemic heart disease, and acute coronary syndrome. Only randomized controlled trials (RCTs) that compared the use of IABP or non-IABP support in AMI with or without cardiogenic shock were included. Two researchers performed data extraction independently, and at the mean time, the risk of bias among those RCTs was also assessed.Of 3026 citations, 17 studies (n = 3226) met the inclusion criteria. There is no significant difference between IABP group and control group on the short-term mortality (relative risk [RR], 0.90; 95% confidence interval [CI], 0.77-1.06; P = 0.214) and long-term mortality (RR, 0.91; 95% CI, 0.79-1.04; P = 0.155) in AMI patients with or without cardiogenic shock. These results were consistent when the analysis was performed on studies that only included patients with cardiogenic shock, both on short-term mortality (RR, 0.91; 95% CI, 0.77-1.08; P = 0.293) and long-term mortality (RR, 0.95; 95% CI, 0.83-1.10; P = 0.492). Similar result was also observed in AMI patients without cardiogenic shock. Furthermore, the risks of hemorrhage (RR, 1.49; 95% CI, 1.09-2.04; P = 0.013) and recurrent ischemia (RR 0.54, 95% CI 0.37 to 0.79; P = 0.002) were significantly higher in IABP group compared with control group.We did not observe substantial benefit from IABP application in reducing the short- and long-term mortality, while it might promote the risks of hemorrhage and recurrent ischemia. Therefore, IABP may be not an optimal therapy in AMI with or without cardiogenic shock until more elaborate classification is used for selecting appropriate patients.