Comparison of hemodynamic effects of enhanced external counterpulsation and intra-aortic balloon pumping in patients with acute myocardial infarction

Enhanced external counterpulsation treatment improves multi-organ hemodynamics for postoperative liver transplantation patient. A case report

INTRODUCTION

Post liver transplantation (LT) patients endure high morbidity rate of multi-organ ischemic symptoms following reperfusion. We hypothesize that enhanced external counterpulsation (EECP) as a typical non-invasive assisted circulation procedure, which can efficiently inhibit the relative ischemic symptoms via the systemic improvement of hemodynamics.

CASE PRESENTATION

A 51-year-old male patient, 76 kg, 172 cm, received orthotopic LT surgery for viral hepatitis B induced acute-on-chronic liver failure hepatic failure. His medical records revealed ischemic symptoms in multi-organ at the time of hospital discharge, including headache, refractory insomnia, abdominal paralysis, and lower limb pain. The EECP treatment was introduced for assisted rehabilitation and to improve the postoperative quality of life. Doppler Ultrasound examination showed significant augmentation of blood flow volume in the carotid arteries, the hepatic artery, the portal vein and the femoral artery during EECP intervention. A standard 35-hour EECP treatment led to significant improvement in quality of life, e.g. sleep quality and walking ability.

CONCLUSION

We report a case of multi-organ ischemic symptoms in a post LT patient. EECP treatment can significantly improve the quality of life via the systematic promotion of hemodynamics.

Standard CPR versus interposed abdominal compression CPR in shunted single ventricle patients: comparison using a lumped parameter mathematical model

INTRODUCTION

Cardiopulmonary resuscitation (CPR) in the shunted single-ventricle population is associated with poor outcomes. Interposed abdominal compression-cardiopulmonary resuscitation, or IAC-CPR, is an adjunct to standard CPR in which pressure is applied to the abdomen during the recoil phase of chest compressions.

METHODS

A lumped parameter model that represents heart chambers and blood vessels as resistors and capacitors was used to simulate blood flow in both Blalock-Taussig-Thomas and Sano circulations. For standard CPR, a prescribed external pressure waveform was applied to the heart chambers and great vessels to simulate chest compressions. IAC-CPR was modelled by adding phasic compression pressure to the abdominal aorta. Differential equations for the model were solved by a Runge-Kutta method.

RESULTS

In the Blalock-Taussig-Thomas model, mean pulmonary blood flow during IAC-CPR was 30% higher than during standard CPR; cardiac output increased 21%, diastolic blood pressure 16%, systolic blood pressure 8%, coronary perfusion pressure 17%, and coronary blood flow 17%. In the Sano model, pulmonary blood flow during IAC-CPR increased 150%, whereas cardiac output was improved by 13%, diastolic blood pressure 18%, systolic blood pressure 8%, coronary perfusion pressure 15%, and coronary blood flow 14%.

CONCLUSIONS

In this model, IAC-CPR confers significant advantage over standard CPR with respect to pulmonary blood flow, cardiac output, blood pressure, coronary perfusion pressure, and coronary blood flow. These results support the notion that single-ventricle paediatric patients may benefit from adjunctive resuscitation techniques, and underscores the need for an in-vivo trial of IAC-CPR in children.

Enhanced external counterpulsation: A new method to alleviate contrast-induced acute kidney injury

BACKGROUND

Contrast-induced acute kidney injury (CI-AKI) is a common complication after exposure to contrast media. Renal ischaemia occurs in the initial stage of CI-AKI, however, there are very few effective measures to improve renal perfusion.

METHODS

A total of 114 patients with an estimated glomerular filtration rate (eGFR) of 60-89 ml/min/1.73m² were randomly assigned to two groups: enhanced external counterpulsation (EECP) group (N = 57) and control group (N = 57). Two hours after contrast exposure, EECP group received EECP treatment for 1 h while no intervention was performed control group. The primary outcome was the incidence of serum cystatin C concentration to 10% above the baseline concentration at 24 h after contrast administration. The secondary outcomes were the incidence of CI-AKI (defined as an increase in serum creatinine concentration to ≥0.5 mg/dl or by 25% compare to the baseline after contrast exposure), contrast clearance and adverse clinical events.

RESULTS

The primary outcome was observed in 26 patients (6 EECP and 20 control; 11% vs. 35%; P = 0.002). CI-AKI occurred in four patients (0 EECP and 4 control; 0% vs. 7%; P = 0.042). The clearance rate of iopromide in the initial 3 h was significantly different between EECP and control group (59.92 ± 8.84 vs 46.80 ± 9.26 ml/min/1.73 m²; P < 0.001). No adverse clinical events were observed in this study.

CONCLUSIONS

This study demonstrates that EECP increases the contrast clearance and may have an effect in reducing the risk of CI-AKI. The study has been registered in Chinese Clinical Trial Registry (ChiCTR 2,000,039,190).

Reduction in risk of contrast-induced nephropathy in patients with chronic kidney disease and diabetes mellitus by enhanced external counterpulsation

OBJECTIVE

To evaluate the efficacy of enhanced external counterpulsation (EECP) in the prevention of contrast-induced nephropathy (CIN) in patients with combined chronic kidney disease (CKD) and diabetes mellitus (DM) by comparing the changes in renal function-related indicators in patients before and after coronary angiography (CAG) or percutaneous coronary intervention (PCI).

METHODS

There were 230 subjects consecutively included in the study. Of these, 30 cases with DM underwent rehydration therapy, and 200 cases underwent EECP therapy in addition to rehydration therapy, comprising 53 patients with DM and 147 patients without. All the patients were tested to measure the renal function indicators before and after CAG/PCI.

RESULTS

The postoperative results of blood urea nitrogen (BUN), serum creatinine (Scr), estimated glomerular filtration rate (eGFR), B2 microglobulin, and high-sensitivity C-reactive protein in the three groups showed a statistically significant difference (P < 0.05). After EECP therapy, patients with DM showed a significant decrease in BUN (9.1 ± 4.2 vs. 7.2 ± 3.0, t = 3.899, P < 0.001) and a significant increase in eGFR (41.5 ± 12.7 vs. 44.0 ± 15.6, t = -2.031, P = 0.047), while the patients without DM showed a more significant difference (P < 0.001). Patients with DM showed a lower percentage of elevated Scr (66.7% vs. 43.4%, P = 0.042), a higher percentage of elevated eGFR (30.0% vs. 52.8%, P = 0.044), and a lower incidence of CIN (16.7% vs. 3.8%, P = 0.042) after EECP therapy.

CONCLUSION

Treatment with EECP can reduce Scr in patients with combined CKD and DM post CAG/PCI, increase eGFR, and decrease the incidence of CIN.

Hemodynamic Responses in Carotid Bifurcation Induced by Enhanced External Counterpulsation Stimulation in Healthy Controls and Patients With Neurological Disorders

Enhanced external counterpulsation is a Food and Drug Administration–approved, non-invasive, assisted circulation therapy for ischemic cardiovascular and cerebrovascular diseases. Previous studies have confirmed that EECP stimulation induces largely different cerebral hemodynamic responses in patients with ischemic stroke and healthy controls. However, the underlying mechanisms remain uncertain. We hypothesize that different blood redistributions at the carotid bifurcation may play a key role. Ten subjects were enrolled in this study, namely, five patients with neurological disorders and five young healthy volunteers as controls. Magnetic resonance angiography (MRA) was performed on the carotid artery. All the subjects received a single session of EECP treatment, with external cuff pressures ranging from 20 to 40 kPa. Vascular ultrasound measurements were taken in the common carotid artery (CCA), external carotid artery (ECA) and internal carotid artery (ICA). Three-dimensional patient-specific numerical models were developed to calculate the WSS-derived hemodynamic factors. The results indicated that EECP increased CCA and ECA blood flow in both groups. The ICA blood flow in the patient group exhibited a mean increase of 6.67% during EECP treatment compared with the pre-EECP condition; a mean decrease of 9.2% was observed in the healthy control group. EECP increased the averaged wall shear stress (AWSS) throughout the carotid bifurcation in the patient group; the ICA AWSS of the healthy group decreased during EECP. In both groups, the oscillatory shear index (OSI) in the ICA increased proportionally with external cuff pressure. In addition, the relative resident time (RRT) was constant or slightly decreased in the CCA and ECA in both groups but increased in the ICA. We suggest that the benefits of EECP to patients with neurological disorders may partly result from blood flow promotion in the ICA and increase in WSS at the carotid bifurcation. In the healthy subjects, the ICA blood flow remained constant during EECP, although the CCA blood flow increased significantly. A relatively low external cuff pressure (20 kPa) is recommended as the optimal treatment pressure for better hemodynamic effects. This study may play an important role in the translation of physiological benefits of EECP treatment in populations with or without neurological disorders.

Effects of enhanced external counterpulsation on exercise capacity and quality of life in patients with chronic heart failure: A meta-analysis

BACKGROUND

This meta-analysis aimed to synthesize randomized controlled trials to evaluate the effects of enhanced external counterpulsation (EECP) on exercise capacity and quality of life in patients with chronic heart failure (CHF).

METHODS

Both English and Chinese databases were searched from their inception to June 30, 2020 (PubMed, EMBASE, Cochrane Library, CINAHL (EBSCO), Web of Science for English publications and Chinese Biomedical Database, China National Knowledge Infrastructure, Wanfang Data for Chinese publication). Titles, abstracts, and full-text articles were screened against study inclusion criteria: randomized controlled trials studying EECP intervention for patients with CHF. The meta-analysis was conducted with Revman 5.3 or STATA 16.0.

RESULTS

Eight randomized controlled trials were included. EECP induced significant improvement in 6-min walking distance (WMD=84.79 m; 95% CI, 47.64 to 121.95; P < .00001). Moreover, EECP was beneficial for left ventricular ejection fraction (SMD = 0.64; 95% CI,0.29 to 1.00; P = .0004), and N-terminal pro brain natriuretic peptide (SMD = -0.61; 95%CI, -1.20 to -0.01; P = 0.04).However, compared with the control groups, EECP did not significantly reduce the Minnesota Living with Heart Failure Questionnaire scores(WMD, -9.28; 95% CI, -19.30 to 0.75; P = 0.07).

CONCLUSIONS

Despite heterogeneity and risk of bias, this meta-analysis confirms that EECP can improve exercise capacity in CHF patients, especially the elderly. However, the evidence that EECP improves the quality of life in patients with CHF is still insufficient. More and larger well-designed randomized controlled trials are still warranted.

REGISTRATION INFORMATION

PROSPERO registration no. CRD 42020188848.

Efficacy of Enhanced External Counterpulsation in Patients With Chronic Refractory Angina on Canadian Cardiovascular Society (CCS) Angina Class: An Updated Meta-Analysis

A growing number of patients with chronic artery disease suffer from angina, despite the optimal medical management (ie, β-blockers, calcium channel blockers, and long-acting nitrates) and revascularization. Currently, enhanced external counterpulsation (EECP) therapy has been verified as a noninvasive, safe therapy for refractory angina. The study was designed to evaluate the efficacy of EECP in patients with chronic refractory angina according to Canadian Cardiovascular Society (CCS) angina class.We identified systematic literature through MEDLINE, EMBASE, the Cochrane Clinical Trials Register Database, and the ClinicalTrials. gov Website from 1990 to 2015. Studies were considered eligible if they were prospective and reported data on CCS class before and after EECP treatment. Meta-analysis was performed to assess the efficacy of EECP therapy by at least 1 CCS angina class improvement, and proportion along with the 95% confidence interval (CI) was calculated. Statistical heterogeneity was calculated by I statistic and the Q statistic. Sensitivity analysis was addressed to test the influence of trials on the overall pooled results. Subgroup analysis was applied to explore potential reasons for heterogeneity.Eighteen studies were enrolled in our meta-analysis. Pooled analysis showed 85% of patients underwent EECP had a reduction by at least one CCS class (95%CI 0.81-0.88, I = 58.5%, P < 0.001). The proportion of patients enrolled at primarily different studies with chronic heart failure (CHF) improved by at least 1 CCS class was about 84% after EECP (95%CI 0.81-0.88, I = 32.7%, P = 0.1668). After 3 large studies were excluded, the pooled proportion was 82% (95%CI 0.79-0.86, I = 18%, P = 0.2528). Funnel plot indicated that some asymmetry while the Begg and Egger bias statistic showed no publication bias (P = 0.1495 and 0.2859, respectively).Our study confirmed that EECP provided an effective treatment for patients who were unresponsive to medical management and/or invasive therapy. However, the long-term benefits of EECP therapy needed further studies to evaluate in the management of chronic refractory angina.

Feasibility and Safety of Using External Counterpulsation to Augment Cerebral Blood Flow in Acute Ischemic Stroke-The Counterpulsation to Upgrade Forward Flow in Stroke (CUFFS) Trial

BACKGROUND

External counterpulsation (ECP) increases perfusion to a variety of organs and may be helpful for acute stroke.

METHODS

We conducted a single-blinded, prospective, randomized controlled feasibility and safety trial of ECP for acute middle cerebral artery (MCA) ischemic stroke. Twenty-three patients presenting within 48 hours of symptom onset were randomized into one of two groups. One group was treated with ECP for 1 hour at a pressure of up to 300 mmHg ("full pressure"). During the procedure, we also determined the highest possible pressure that would augment MCA mean flow velocity (MFV) by 15%. The other group was treated with ECP at 75 mmHg ("sham pressure"). Transcranial Doppler MCA flow velocities and National Institutes of Health Stroke Scale (NIHSS) scores of both groups were checked before, during, and after ECP. Outcomes were assessed at 30 days after randomization.

RESULTS

Although the procedures were feasible to implement, there was a frequent inability to augment MFV by 15% despite maximal pressures in full-pressure patients. In sham-pressure patients, however, MFV frequently increased as shown by increases in peak systolic velocity and end diastolic velocity. In both groups, starting ECP was often associated with contemporaneous improvements in NIHSS stroke scores. There were no between-group differences in NIHSS, modified Rankin Scale Scores, and Barthel Indices, and no device or treatment-related serious adverse events, deaths, intracerebral hemorrhages, or episodes of acute neuro-worsening.

CONCLUSIONS

ECP was safe and feasible to use in patients with acute ischemic stroke. It was associated with unexpected effects on flow velocity, and contemporaneous improvements in NIHSS score regardless of pressure used, with a possibility that even very low ECP pressures had an effect. Further study is warranted.

Intra-aortic balloon pump counterpulsation (IABP) for myocardial infarction complicated by cardiogenic shock

BACKGROUND

Intra-aortic balloon pump counterpulsation (IABP) is currently the most commonly used mechanical assist device for patients with cardiogenic shock due to acute myocardial infarction. Although there has been only limited evidence from randomised controlled trials, the previous guidelines of the American Heart Association/American College of Cardiology (AHA/ACC) and the European Society of Cardiology (ESC) strongly recommended the use of the IABP in patients with infarction-related cardiogenic shock on the basis of pathophysiological considerations, non-randomised trials and registry data. The recent guidelines downgraded the recommendation based on a meta-analysis which could only include non-randomised trials showing conflicting results. Up to now, there have been no guideline recommendations and no actual meta-analysis including the results of the large randomised multicentre IABP-SHOCK II Trial which showed no survival benefit with IABP support. This systematic review is an update of the review published in 2011.

OBJECTIVES

To evaluate, in terms of efficacy and safety, the effect of IABP versus non-IABP or other assist devices guideline compliant standard therapy on mortality and morbidity in patients with acute myocardial infarction complicated by cardiogenic shock.

SEARCH METHODS

Searches of CENTRAL, MEDLINE (Ovid) and EMBASE (Ovid), LILACS, IndMed and KoreaMed, registers of ongoing trials and proceedings of conferences were updated in October 2013. Reference lists were scanned and experts in the field contacted to obtain further information. No language restrictions were applied.

SELECTION CRITERIA

Randomised controlled trials on patients with acute myocardial infarction complicated by cardiogenic shock.

DATA COLLECTION AND ANALYSIS

Data collection and analysis were performed according to the published protocol. Individual patient data were provided for six trials and merged with aggregate data. Summary statistics for the primary endpoints were hazard ratios (HRs) and odds ratios (ORs) with 95% confidence intervals (CIs).

MAIN RESULTS

Seven eligible studies were identified from a total of 2314 references. One new study with 600 patients was added to the original review. Four trials compared IABP to standard treatment and three to other percutaneous left assist devices (LVAD). Data from a total of 790 patients with acute myocardial infarction and cardiogenic shock were included in the updated meta-analysis: 406 patients were treated with IABP and 384 patients served as controls; 339 patients were treated without assisting devices and 45 patients with other LVAD. The HR for all-cause 30-day mortality of 0.95 (95% CI 0.76 to 1.19) provided no evidence for a survival benefit. Different non-fatal cardiovascular events were reported in five trials. During hospitalisation, 11 and 4 out of 364 patients from the intervention groups suffered from reinfarction or stroke, respectively. Altogether 5 out of 363 patients from the control group suffered from reinfarction or stroke. Reocclusion was treated with subsequent re-revascularization in 6 out of 352 patients from the intervention group and 13 out of 353 patients of the control group. The high incidence of complications such as moderate and severe bleeding or infection in the control groups has to be attributed to interventions with other LVAD. Possible reasons for bias were more frequent in small studies with high cross-over rates, early stopping and the inclusion of patients with IABP at randomisation.

AUTHORS' CONCLUSIONS

Available evidence suggests that IABP may have a beneficial effect on some haemodynamic parameters. However, this did not result in survival benefits so there is no convincing randomised data to support the use of IABP in infarct-related cardiogenic shock.

Novel external counterpulsation system, compact counterpulsation, was effective to treat severe ischemic heart failure: a case report

Compact counterpulsation (CP) is a novel external counterpulsation system. The preoperative clinical utility of compact CP therapy in patients has not been established. In the present report, we describe a case wherein compact CP therapy was successfully used to treat severe ischemic heart failure. A 70-year-old man was diagnosed with ischemic heart disease and mitral valve regurgitation at 61 years of age. Therefore, he underwent coronary artery bypass and mitral valve plasty. The patient's condition started to gradually deteriorate at 68 years of age, and he became progressively dependent on catecholamine support. Mitral valve regurgitation recurred, which caused worsening of heart function. Before a mitral valve replacement, the patient had been treated with compact CP therapy to improve heart function and general condition. The patient's clinical condition improved with compact CP therapy after only ten sessions; in addition, he could be weaned off catecholamine support. No adverse effects were observed, and therefore, he could complete the CP therapy as an outpatient. Mitral valve replacement was performed after a total of 44 sessions. The patient had an uneventful postoperative course and was discharged on the 18th postoperative day. Compact CP therapy was thus performed on our patient without any discomfort and appears to be an effective treatment for patients with severe ischemic heart failure.

Reduced peripheral vascular reactivity in refractory angina pectoris: Effect of enhanced external counterpulsation

AIMS

To examine if the skin microvascular bed is altered and can be modified by enhanced external counterpulsation (EECP) in patients with chronic refractory angina.

METHODS

Twenty patients diagnosed with refractory angina were divided into EECP (n = 10) or no EECP (n = 10) groups. The data were compared to matched healthy subjects (n = 20). The cutaneous forearm microvascular blood flow was measured by Laser-Doppler flowmetry. The vascular responsiveness to iontophoretic administration of acetylcholine (ACh), sodium nitroprusside (SNP) and local skin warming were studied. Measurements of Canadian Cardiovascular Society (CCS)-class, blood pressure and plasma samples were registered.

RESULTS

EECP patients showed reduced CCS-class compared to no EECP (P < 0.05). Both EECP and no EECP (P < 0.05) groups had decreased systolic blood pressure (SBP) as compared to SBP at baseline (P < 0.05). There was no difference in resting blood flow between the two refractory groups at baseline as well as after EECP and seven weeks of follow-up. Responses to heating, the responses to ACh and SNP in the cutaneous microcirculation were lower in both groups of refractory angina patients as compared to healthy subjects (P < 0.05). EECP patients corresponded positively to the treatment shown by reduced plasma level of soluble interleukin-2 receptor and CCS-class.

CONCLUSIONS

Refractory angina patients have reduced responsiveness in their cutaneous microcirculation to ACh, SNP and heat compared to healthy subjects. Although EECP reduced the CCS-class, this effect was not associated with improvements in responsiveness of the cutaneous microcirculation.

Vasculoprotective properties of enhanced external counterpulsation for coronary artery disease: beyond the hemodynamics

A growing pool of evidence has shown that enhanced external counterpulsation (EECP) is a non-invasive, safe, low-cost, and highly beneficial therapy for patients with coronary artery disease. However, the exact mechanisms of benefit exerted by EECP therapy remain only partially understood. The favorable hemodynamic effects of EECP were previously considered as the primary mechanism of action. Nevertheless, recent advances have shed light on the shear stress-increasing effects of EECP which are vasculoprotective and anti-atherosclerotic. EECP-induced endothelial shear stress increase may lead to improvement in endothelial function and morphology, attenuation of oxidative stress and inflammation, and promotion of angiogenesis and vasculogenesis. This review summarizes evidence of the potential mechanisms contributing to the immediate and long-term benefits of EECP, from the perspective of its shear stress-increasing effects.

Effect of external counterpulsation on cardiac work following cardiac surgery: implications of the mechanism responsible for clinical benefits

BACKGROUND

External counterpulsation (ECP) has been recognized as a non-invasive treatment for chronic refractory angina or heart failure. However, the mechanisms responsible for the clinical benefits of ECP therapy remain elusive. Moreover, the clinical significance of ECP therapy for postoperative patients has not been established yet.

METHODS

Six adult patients received ECP therapy for 60 min under pulmonary artery catheter monitoring after cardiac surgery. Hemodynamic data were obtained before ECP therapy (pre-ECP), 20 min after ECP was commenced (20-min-ECP), 40 min after ECP was commenced (40-min-ECP), and after ECP therapy (post-ECP).

RESULTS

The mean right atrial pressure (pre-ECP: 9 ± 4 mmHg; 20-min-ECP: 12 ± 5 mmHg; 40-min-ECP: 12 ± 4 mmHg; and post-ECP: 9 ± 4 mmHg), pulmonary wedge pressure (16 ± 6 mmHg, 20 ± 7 mmHg, 20 ± 7 mmHg, and 17 ± 7 mmHg, respectively), cardiac index (2.4 ± 0.4 l/min/m(2), 2.8 ± 0.6 l/min/m(2), 2.7 ± 0.5 l/min/m(2), and 2.5 ± 0.4 l/min/m(2), respectively), cardiac work index (2.5 ± 0.4 kgm/m(2), 3.3 ± 0.8 kgm/m(2), 3.1 ± 0.8 kgm/m(2), and 2.6 ± 0.5 kgm/m(2), respectively), and left ventricular stroke work index (32 ± 7 gm/m(2), 41 ± 12 gm/m(2), 39 ± 12 gm/m(2), and 33 ± 8 gm/m(2), respectively) significantly (p<0.05) increased after ECP was commenced (pre-ECP vs. 20-min-ECP) and decreased after ECP was discontinued (40-min-ECP vs. post-ECP). Significant (p<0.001) diastolic augmentation (20-min-ECP: 24 ± 6%, 40-min-ECP: 23 ± 5%) and systolic unloading (3 ± 1%, and 3 ± 1%, respectively) were obtained. No clinical adverse effects were observed.

CONCLUSIONS

ECP increases venous return, cardiac output, and cardiac work in addition to diastolic augmentation and systolic unloading. These actions may play important roles in the clinical benefits of ECP therapy. Our data also suggest that ECP is beneficial for patients undergoing cardiac surgery.

A novel external counterpulsation system for coronary artery disease and heart failure: pilot studies and initial clinical experiences

External counterpulsation (ECP) is a beneficial and noninvasive treatment for coronary artery disease or heart failure; however, it still has a lot of limitations. We used a novel ECP system, Compact CP, the main feature of which is the double-lumen cuff that reduces the impact of cuff inflation and the size of the air compressor. The first lumen was a contact cuff that was attached to the legs with a constant pressure (8 kPa). The second lumen was a main cuff that was inflated and deflated with a driving pressure and synchronized to the cardiac cycle. In this report, we describe the results of four pilot studies in a total number of 39 healthy volunteers and initial clinical experiences of this system in three patients. The pilot studies demonstrated that the ECP system provided significant diastolic augmentation and systolic unloading. It also achieved a satisfactory diastolic/systolic pressure ratio (1.00 ± 0.06) with a high comfort level at a driving pressure of 40 kPa. Higher pressure (50-70 kPa) increased the assist performance but decreased the comfort level. ECP was also applied with a patient with chronic refractory angina and two patients with postoperative heart failure following cardiac surgery. The clinical conditions improved. No adverse effect was observed. Our novel ECP system is safe, effective, and promising in the treatment of coronary artery disease or heart failure. Further clinical investigations are needed to support the significance of this system.

Hyperacute ischemic stroke management: reperfusion and evolving therapies

Management of acute ischemic stroke patients is organized around several priorities aimed at ensuring optimal patient outcomes, the first of which is reperfusion therapy, followed by determination of pathogenic mechanism by provision of a comprehensive workup to determine probable cause of the ischemic stroke or transient ischemic attack, for the purpose of providing appropriate prophylaxis for subsequent events. Provision of secondary prevention measures along with therapies that prevent complications associated with neurologic disability, and evaluation for the most appropriate level of rehabilitation services are the final priorities during acute hospitalization. This article provides an overview of reperfusion therapies and emerging hemodynamic treatments for hyperacute ischemic strokes. Gaps in the scientific evidence that are driving current blood flow augmentation research are identified.

Enhanced external counter pulsation in treatment of refractory angina pectoris: two year outcome and baseline factors associated with treatment failure

Background

Enhanced external counter pulsation (EECP) is a non-invasive treatment option for patients with refractory angina pectoris ineligible to further traditional treatment. The aim of this study was to evaluate the effect of EECP on patients at a Scandinavian medical centre and to investigate if outcome can be predicted by analysing baseline factors.

Methods

86 consecutive patients (70 male, 16 female) were treated with EECP and followed for two years post treatment. Canadian cardiovascular society (CCS) class was analysed, and medication and adverse clinical events were researched prior to EECP, at the end of the treatment, and at six, 12 and 24 months thereafter. Patients responding to therapy by improving at least one CCS class were compared with those who failed to respond. Any differences in background factors were recorded and analysed.

Results

79% of the patients responded to therapy by improving at least one CCS class. In general, the CCS class improved by one class after EECP treatment (3.05 before versus 2.14 after treatment). A total of 61.5% of the initial responders showed sustained improvement at the 12 month follow-up while 29% presented sustained improvement after 24 months. Treatment was most effective among patients suffering from CCS class III-IV angina pectoris, while patients suffering from CCS class II angina pectoris improved transiently but failed to show sustained improvement after the 12 month follow-up. Diabetes mellitus and calcium channel antagonists were more common among the non-responders (p < 0.05).

Conclusion

This study confirms the safety and efficiency of EECP as a treatment option for patients suffering from refractory angina pectoris. The therapy is most beneficial in patients suffering from severe angina (CCS III-IV) while sustained response to therapy could not be verified among patients suffering from CCS class II angina pectoris.

Perfusion Augmentation in Acute Stroke Using Mechanical Counter-Pulsation–Phase IIa

Background and Purpose— External counterpulsation (ECP) improves coronary perfusion, increases left ventricular stroke volume similar to intraaortic balloon counterpulsation, and recruits arterial collaterals within ischemic territories. We sought to determine ECPs effect on middle cerebral artery (MCA) blood flow augmentation in normal controls as a first step to support future clinical trials in acute stroke.

Methods— Healthy volunteers were recruited and screened for exclusions. Bilateral 2-MHz pulsed wave transcranial Doppler (TCD) probes were mounted by head frame, and baseline M1 MCA TCD measurements were obtained. ECP was then initiated using standard procedures for 30 minutes, and TCD readings were repeated at 5 and 20 minutes. Physiological correlates associated with ECP-TCD waveform morphology were identified, and measurable criteria for TCD assessment of ECP arterial mean flow velocity (MFV) augmentation were constructed.

Results— Five subjects were enrolled in the study. Preprocedural M1 MCA TCD measurements were within normal limits. Onset of ECP counterpulsation produced an immediate change in TCD waveform configuration with the appearance of a second upstroke at the dicrotic notch, labeled peak diastolic augmented velocity (PDAV). Although end-diastolic velocities did not increase, both R-MCA and L-MCA PDAVs were significantly higher than baseline end-diastolic values ( P <0.05 Wilcoxon rank-sum test) at 5 and 20 minutes. Augmented MFVs (aMFVs) were also significantly higher than baseline MFV in the R-MCA and L-MCA at both 5 and 20 minutes ( P <0.05).

Conclusions— ECP induces marked changes in cerebral arterial waveforms and augmented peak diastolic and mean MCA flow velocities on TCD in 5 healthy subjects.

Enhanced external counterpulsation in the treatment of chronic refractory angina: a long-term follow-up outcome from the International Enhanced External Counterpulsation Patient Registry

BACKGROUND

The management of patients who suffer from medically refractory angina and are unsuitable for conventional revascularization therapy is often unsatisfactory. Enhanced external counterpulsation (EECP) is a noninvasive treatment that is safe and effective immediately after a course of treatment. However, the duration of benefit is less certain.

HYPOTHESIS

To evaluate the 3-year outcome of EECP treatment.

METHODS

One thousand four hundred and twenty seven patients from 36 centers registered in the International EECP Patient Registry (IEPR)-Phase 1 was prospectively followed for a median of 37 months. Two hundred and twenty patients (15.4%) died, while 1,061 patients (74.4%) completed their follow-up.

RESULTS

The mean age was 66+/-11 years and 72% were men. Seventy-six percent had multivessel coronary disease for 11+/-8 years. Eighty-eight percent had a prior percutaneous or surgical revascularization and 82% were unsuitable for further coronary intervention. Immediately post-EECP, the proportion of patients with severe angina (Canadian Cardiovascular Angina Classification [CCS] III/IV) were reduced from 89% to 25%, p<0.001. The CCS class was improved by at least 1 class in 78% of the patients and by at least 2 classes in 38%. This was sustained in 74% of the patients during follow-up.Thirty-six percent of the patients had CCS II or less angina, which was better than pre-EECP state without a major adverse cardiovascular event during follow-up. More severe baseline angina and a history of heart failure or diabetes were independent predictors of unfavorable outcome.

CONCLUSION

An EECP improves angina and quality of life immediately after a course of treatment. For most of the patients, these beneficial effects are sustained for 3 years.

The role of enhanced external counterpulsation in the treatment of angina and heart failure

As the incidence of angina and heart failure continue to rise, new therapeutic options will be needed to treat patients who remain symptomatic or who are intolerant to current treatment. Enhanced external counterpulsation (EECP) is a noninvasive modality being investigated in both angina and congestive heart failure patients. It has been proven to provide symptomatic benefit in angina patients, but has not been proven to show an increase in life expectancy or decrease in cardiovascular events. EECP in heart failure has been proven to be safe, but its efficacy is still uncertain. The present paper summarizes the current literature on the clinical use of EECP in angina and heart failure.

ECG-triggered muscular counterpulsation for treatment of low cardiac output

BACKGROUND

Skeletal muscular counterpulsation (MCP) has been used as a new noninvasive technique for treatment of low cardiac output. The MCP method is based on ECG-triggered skeletal muscle stimulation. The purpose of the present study was to evaluate acute hemodynamic changes induced by MCP in the experimental animal.

METHODS

Eight anaesthetized pigs (43+/-4 kg) were studied at rest and after IV â-blockade (10 mg propranolol) before and after MCP. Muscular counterpulsation was performed on both thighs using trains (75 ms duration) of multiple biphasic electrical impulses with a width of 1 ms and a frequency of 200 Hz at low (10 V) and high (30 V) amplitude. ECG-triggering was used to synchronize stimulation to a given time point. LV pressure-volume relations were determined using the conductance catheter. After baseline measurements, MCP was carried out for 10 minutes at low and high stimulation amplitude. The optimal time point for MCP was determined from LV pressure-volume loops using different stimulation time points during systole and diastole. Best results were observed during end-systole and, therefore, this time point was used for stimulation.

RESULTS

Under control conditions, MCP was associated with a significant decrease in pulmonary vascular resistance (-18%), a decrease in systemic vascular resistance (-11%) and stroke work index (-4%), whereas cardiac index (+2%) and ejection fraction (+6%) increased slightly. Pressure-volume loops showed a leftward shift with a decrease in end-systolic volume. After â-blockade, cardiac function decreased (HR, MAP, EF, dP/dt max), but it improved with skeletal muscle stimulation (HR +10% and CI +17%, EF +5%). There was a significant decrease in pulmonary (-19%) and systemic vascular resistance (-29%).

CONCLUSIONS

In the animal model, ECG-triggered skeletal muscular counterpulsation is associated with a significant improvement in cardiac function at baseline and after IV â-blockade. Thus, MCP represents a new, non-invasive technique which improves cardiac function by diastolic compression of the peripheral arteries and veins, with a decrease in systemic vascular resistance and increase in cardiac output.

Impact of External Counterpulsation Treatment on Emergency Department Visits and Hospitalizations in Refractory Angina Patients With Left Ventricular Dysfunction

Patients with refractory angina and left ventricular (LV) dysfunction exert an enormous burden on health care resources primarily because of the number of recurrent emergency department (ED) visits and hospitalizations. Enhanced external counterpulsation (EECP) therapy has emerged as a treatment option for patients with angina and LV dysfunction and has been shown to improve clinical outcomes and LV function. Improvements in symptoms and laboratory assessments in these patients, however, do not necessarily correlate with a reduction in ED visits and hospitalizations. This is the first study to assess the impact of EECP therapy on ED visits and hospitalization rates at 6-month follow-up. This prospective cohort study included 450 patients with LV dysfunction (ejection fraction <or=40%) treated with EECP therapy for refractory angina. Clinical outcomes, number of all-cause ED visits, and hospitalizations within the 6 months before EECP therapy were compared with those at 6-month follow-up. Despite the unfavorable risk profile, refractory angina patients with LV dysfunction achieved a substantial reduction in all-cause ED visits and hospitalization rates at 6-month follow-up. EECP therapy appears to offer an effective adjunctive treatment option for this group of patients.

Cardiac failure: Mechanical support strategies

OBJECTIVE

Mechanical support of the circulation is necessary when heart failure becomes refractory to medical support and is typically applied when organ dysfunction occurs as a result of hypoperfusion. However, in timing the intervention, it is important to apply mechanical support before multiple organ failure occurs. The objective of this work is to review the current strategies for mechanical circulatory support in patients with refractory cardiac failure.

DESIGN

A review of the use of mechanical circulatory support is presented for patients with refractory cardiac failure.

PATIENTS

Data are taken from human studies that were selected to best exemplify the results that may be obtained from various forms of mechanical circulatory support.

INTERVENTIONS

Commonly applied forms of mechanical support include mechanical ventilatory support, intraaortic balloon counterpulsation, and hemodialysis or ultrafiltration. If these measures fail, mechanical support of the circulation with ventricular assist devices is possible in specialized centers with expertise in the implantation and management of these devices. The decision to pursue mechanical circulatory support in the critically ill patient is based on the cause of acute decompensation, the potential reversibility of the condition, and the possibility for other treatments to improve the underlying condition or, in highly selected cases, heart transplantation. Newer forms of ventricular assistance that require less surgery are becoming available and may allow use in a broader range of critically ill patients.

MAIN RESULTS

There is a range of means to mechanically support the circulation in patients with advanced heart failure.

CONCLUSIONS

A variety of means to support the circulation have found application in the treatment of patients with refractory heart failure. More work is required to best identify populations who will benefit from the therapy and to refine the therapy to reduce associated risks.

Mechanisms and evidence for the role of enhanced external counterpulsation in heart failure management

Balloon counterpulsation has gained widespread acceptance as a therapy for cardiogenic shock. However, over the past four decades a parallel method of noninvasive counterpulsation, enhanced external counterpulsation (EECP), has been defined and developed. Mechanisms of benefit for this technology continue to emerge and include enhanced coronary and other key target organ perfusion beds. Other mechanisms include angiogenesis and enhanced cellular metabolism. Beyond putative mechanisms there is ample evidence for improved and sustained outcomes in patients with and without left ventricular dysfunction. This evidence comes from long-term registry reports and randomized clinical trials. With respect to heart failure (HF), there is registry, pilot trial, and randomized clinical trial evidence of safety and efficacy. This paper summarizes some of the mechanisms and outcomes of EECP in HF patients and helps to elucidate the role of EECP in the management of patients with chronic HF.

The immediate and long-term outcome of enhanced external counterpulsation in treatment of chronic stable refractory angina

BACKGROUND

Treatment of angina recalcitrant to conventional pharmacological therapy and revascularization remains problematic. Safe, effective and affordable treatments with high patient acceptability are desirable. Enhanced external counterpulsation (EECP) may fulfil these criteria better than many other proposed interventions.

OBJECTIVE

To examine the immediate and long-term effect of EECP in treatment of chronic stable refractory angina.

DESIGN

Prospective observational study of consecutive patients treated with EECP and follow-up for 1 year.

SETTING

Teaching hospital.

MAIN OUTCOME MEASURES

Canadian Cardiovascular Society (CCS) angina grading, weekly angina frequency and glyceryl trinitrate (GTN) use.

RESULTS

Sixty-one patients were treated with EECP and 58 completed a course of treatment. Further analysis is confined to those who completed EECP. About 52% of patients suffered from CCS III and IV angina prior to EECP. Immediately post-EECP, angina improved by at least one CCS class in 86% and by two classes in 59%. At 1-year follow-up, sustained improvement in CCS was observed in 78% of the patients. The median weekly angina frequency and GTN use were significantly reduced immediately after EECP [7 (4-14) vs. 1 (0-4) episodes per week and 7 (2-16) vs. 0 (0-2) times per week respectively, P < 0.0001; data in median (interquartile range)]. The reduction was sustained at 1-year follow-up. In 48 patients, their mean exercise time improved significantly after EECP [301 +/- 130 s vs. 379 +/- 147 s, P < 0.0001]. Major adverse treatment-related events were rare.

CONCLUSION

This study shows that for patients who fail to respond to conventional measures, a high proportion gain symptomatic benefit from EECP.

Two-year clinical outcomes after enhanced external counterpulsation (EECP) therapy in patients with refractory angina pectoris and left ventricular dysfunction (report from The International EECP Patient Registry)

Enhanced external counterpulsation (EECP) is a noninvasive circulatory assist device that has recently emerged as a treatment option for refractory angina in left ventricular (LV) dysfunction. This 2-year cohort study describes the long-term follow-up of patients who had severe LV dysfunction that was treated with EECP for angina pectoris and reports clinical outcomes, event-free survival rates, and the incidence of repeat EECP. This study included 363 patients who had refractory angina and LV ejection fraction < or =35%. Most patients reported quality of life as poor. After completion of treatment, there was a significant decrease in severity of angina class (p < 0.001), and 72% improved from severe angina to no angina or mild angina. Fifty-two percent of patients discontinued nitroglycerin use. Quality of life improved substantially. At 2 years this decrease in angina was maintained in 55% of patients. The 2-year survival rate was 83%, and the major adverse cardiovascular event-free survival rate was 70%. Forty-three percent had no reported cardiac hospitalization; 81% had no reported congestive heart failure events. Repeat EECP was performed in 20% of these patients. The only significant independent predictor of repeat EECP in a proportional hazard model was failure to complete the first EECP treatment course (hazard ratio 2.9, 95% confidence interval 1.7 to 4.9). Improvements in angina symptoms and quality of life were maintained at 2 years. In conclusion, for patients who have high-risk LV dysfunction, EECP offers an effective, durable therapeutic approach for refractory angina. Decreased angina and improvement in quality of life were maintained at 2 years, with modest repeat EECP and low major cardiovascular event rates.

An update on enhanced external counterpulsation

The development of advanced revascularization techniques has resulted in the growth of a subset of patients with coronary artery disease who are nonrevascularizable and are considered to have refractory angina. Enhanced external counterpulsation (EECP) has been developed for the management of these patients with chronic, refractory disease. Evidence has shown that through improvement of vascular endothelial function and recruitment of collateral vessels, EECP provides many clinical benefits. These patients experience sustained decreases in angina, improvement in exercise time, improved myocardial perfusion, and enhanced quality of life. Furthermore, EECP appears to be safe and effective in the treatment of angina in patients with impaired systolic function and has similar potential in patients with congestive heart failure.

Predictors of benefit in angina patients one year after completing enhanced external counterpulsation: initial responders to treatment versus nonresponders

Enhanced external counterpulsation (EECP) has been shown to reduce Canadian Cardiovascular Society angina class. This study examines the factors that affect the reduction at 1 year, especially in patients who do not demonstrate an initial response. The data of 2,007 consecutive patients enrolled in the International EECP Patient Registry were analyzed. After 36.6 +/- 4.9 h of EECP, angina was reduced by at least one class in 82.7%. At 1 year, 35.4% of initial nonresponders and 70.6% of responders remained improved by at least one angina class and free of major adverse cardiovascular events. Multivariate predictors of 1-year benefit are initial response to treatment (odds ratio 4.5, 95% CI 3.5-5.8), baseline angina class compared with class IV (odds ratios: class I 2.1, CI 0.93-4.81; class II 0.62, CI 0.43-0.87; class III 0.80, CI 0.62-1.01) and no history of congestive heart failure (odds ratio 1.41, CI 1.14-1.74).

Enhanced external counterpulsation: a new technique to augment renal function in liver cirrhosis

BACKGROUND

Advanced liver cirrhosis is characterized by cardiovascular changes, such as low arterial blood pressure, peripheral vasodilation and renal vasoconstriction. As a consequence, renal hypoperfusion, impaired diuresis and natriuresis and eventual hepatorenal syndrome may ensue. Previous studies using head-out water immersion to increase central blood volume have demonstrated the functional nature of the renal abnormalities. Enhanced external counterpulsation (EECP) is a new non-invasive cardiac assist device to augment diastolic blood pressure by electrocardiogram-triggered diastolic inflation and deflation of cuffs wrapped around the lower extremities. We investigated whether EECP would improve renal dysfunction of liver cirrhosis.

METHODS

Twelve healthy controls and 19 patients with liver cirrhosis were observed during 2 h of baseline followed by 2 h of EECP. The following parameters of renal and cardiovascular function were measured: renal plasma flow by para-aminohippurate clearance, glomerular filtration rate (GFR) by inulin clearance, urine flow rate, urinary excretion rates of sodium and chloride, mean arterial blood pressure (MAP), renal vascular resistance (RVR) and plasma concentrations of renin, atrial natriuretic peptide (ANP), endothelin-1, antidiuretic hormone, epinephrine and N-epinephrine.

RESULTS

EECP was well tolerated by healthy controls and cirrhotic patients alike. EECP increased MAP (cirrhotic patients: from 74+/-18 to 88+/-20 mmHg, P<0.01; controls: from 89+/-8 to 94+/-5 mmHg, P = NS) and ANP (cirrhotic patients: from 23+/-18 to 30+/-20 ng/l, P<0.05; controls: from 11+/-4 to 16+/-5 ng/l, P<0.01). The plasma renin concentration decreased (cirrhotic patients: from 98+/-98 to 58+/-57 ng/l, P<0.01; controls: from 4.6+/-1.6 to 3.4+/-1.1 ng/l, P<0.01). This was associated with improvement of the urinary flow rate (cirrhotic patients: from 3.6+/-1.8 to 4.6+/-0.7 ml/min, P<0.05; controls: from 1.8+/-1.5 to 2.8+/-1.9 ml/min, P<0.05), as well as of the sodium and chloride excretion rates in both groups. However, in contrast to healthy controls, GFR and renal plasma flow in cirrhotic patients failed to rise significantly. Renal vascular resistance fell numerically in healthy controls (68+/-5 vs 55+/-4 mmHg . min/l; P = NS). In contrast, RVR showed a significant increase by approximately 20% in cirrhosis (67+/-4 vs 80+/-8 mmHg . min/l; P<0.05). Endothelin-1 levels fell in controls (0.38+/-0.42 vs 0.31+/-0.35; P<0.05), whereas they remained statistically unchanged in cirrhotic patients. Epinephrine, N-epinephrine and vasopressin were not altered by EECP in either group.

CONCLUSIONS

EECP is an effective procedure to augment renal excretory function in healthy volunteers as well as in patients with cirrhosis. In healthy volunteers, GFR and renal plasma flow increased during EECP. In contrast, these parameters remained unchanged in the patients and their renal vascular resistance increased during EECP. Therefore, EECP improves diuresis, but does not influence the vasoconstrictive dysregulation of the kidneys in liver cirrhosis.

Periodic acceleration: effects on vasoactive, fibrinolytic, and coagulation factors

Cellular and isolated vessel experiments have shown that pulsatile and laminar shear stress to the endothelium produces significant release of mediators into the circulation. Periodic acceleration (pGz) applied to the whole body in the direction of the spinal axis adds pulses to the circulation, thereby increasing pulsatile and shear stress to the endothelium that should also cause release of mediators into the circulation. The purpose of this study was to determine whether addition of pulses to the circulation through pGzwould be sufficient to increase shear stress in whole animals and to acutely release mediators and how such a physical maneuver might affect coagulation factors. Randomized control experiments were performed on anesthetized, supine piglets. The treatment group (pGz) ( n = 12) received pGzwith a motion platform that moved them repetitively head to foot at ±0.4 g at 180 cpm for 60 min. The control group ( n = 6) was secured to the platform but remained on conventional ventilation throughout the 4-h protocol. Compared with control animals and baseline, pulsatile stress produced significant increases of serum nitrite, prostacyclin, PGE2, and tissue plasminogen activator antigen and activity, as well as D-dimer. There were no significant changes in epinephrine, norepinephrine, cortisol, and coagulation factors between groups or from baseline values. Pulsatile and laminar shear stress to the endothelium induced by pGzsafely produces increases of vasoactive and fibrinolytic activity. pGzhas potential to achieve mediator-related benefits from the actions of nitric oxide and prostaglandins.

Effects of enhanced external counterpulsation on hemodynamics and its mechanism

BACKGROUND

The hemodynamic effects of enhanced external counterpulsation (EECP) and its mechanism(s) were investigated in relation to neurohumoral factors in patients with acute myocardial infarction (AMI).

METHODS AND RESULTS

Twenty-four patients with AMI were studied before, during and after EECP treatment for 60 min. Heart rate (HR), right atrial pressure (RAP), pulmonary capillary wedge pressure (PCWP) and cardiac index (CI) were determined. In addition, circulating concentrations of neurohumoral factors were determined at each time point. HR did not change following EECP treatment. However, RAP and PCWP increased significantly and CI was significantly elevated during EECP and thereafter. Blood atrial natriuretic peptide (ANP) concentration was significantly increased 15 and 60 min after the start of EECP treatment, but brain natriuretic peptide (BNP) did not change. Renin, aldosterone and catecholamine concentrations also did not change.

CONCLUSION

Treatment with EECP resulted in an increased preload because of increased venous return, and CI was increased thereafter. In patients with AMI, EECP increased blood ANP concentration, but not BNP, which suggests that an increase in ANP without an increase in BNP is an important mechanism for the effects of EECP treatment.

Enhanced external counterpulsation does not compromise cerebral autoregulation

OBJECTIVES

Enhanced external counterpulsation (EECP) rhythmically augments blood pressure (BP) by diastolic lower-body compression. Recently, we showed decreased mean cerebral blood flow velocity (CBFVmean) in young healthy persons during EECP, but unchanged CBFVmean in atherosclerotic patients. In this study, we assessed EECP effects on dynamic cerebral autoregulation (CA).

MATERIAL & METHODS

In 23 healthy persons and 15 atherosclerotic patients we monitored heart rate (HR), mean BP (BPmean) and CBFVmean before and during 5 min EECP. We analyzed spectral powers of HR, BPmean and CBFVmean in the low (LF: 0.04-0.15 Hz) and high (HF: 0.15-0.5 Hz) frequency ranges to determine CA from the LF-transfer function gain and phase shift between BPmean and CBFVmean oscillations.

RESULTS

EECP increased HR and BPmean, while transfer function gain and phase shift remained stable.

CONCLUSIONS

Stable gain and phase values suggest that EECP does not compromise CA and, therefore, does not seem to bear cerebrovascular risks.

Effectiveness of enhanced external counterpulsation in patients with left main disease and angina

BACKGROUND

Enhanced external counterpulsation (EECP) is a noninvasive device that uses three pairs of sequentially inflated pneumatic cuffs applied to the lower extremities and synchronized with the heart beat to provide diastolic augmentation, increase coronary blood pressure and flow, venous return and cardiac output, and decrease afterload.

HYPOTHESIS

This study examines the safety and effectiveness of EECP therapy in patients with significant left main coronary artery disease (LMD).

METHODS

In all, 2,861 patients enrolled in the International EECP Patient Registry (IEPR) were divided into three groups, those without LMD (n = 2,377), those with LMD and prior CABG (n = 431), and those with unbypassed LMD (n = 53).

RESULTS

Patients with LMD, with or without prior CABG, were significantly more likely to have triple-vessel disease (98.1 and 88.7%, respectively) than patients without LMD (41.9%). Post-EECP, 74% without LMD, 75% with LMD with prior CABG, and 65% with unbypassed LMD improved their Canadian Cardiovascular Society (CCS) angina by at least one class (p = NS). There were no differences in the mean decrease in weekly angina episodes (7.1 vs. 8.0 vs. 7.6) and in the mean frequency of weekly nitroglycerin use (6.6 vs. 8.1 vs. 8.9). At 6-month follow-up, the CCS class improved further in all three groups, and there was a further reduction in mean weekly angina episodes (4.7 vs. 4.6 vs. 5.3) and nitroglycerin use (6.5 vs. 6.8 vs. 8.2). Kaplan-Meier life table analysis 8 months after starting EECP demonstrated a major cardiovascular event rate of 11.2% in patients without LMD, 15.6% in LMD with CABG, and 24.3% in LMD without prior CABG. Late mortality in unbypassed LMD was 13.2% (confidence interval [CI] 3.3-23.1) versus 4.8% (CI 2.7-7.1) in LMD with CABG, and 2.8% (CI 2.1-3.5) without LMD (p = 0.0039 by log-rank test).

CONCLUSION

Enhanced external counterpulsation is equally effective in relieving angina in patients with or without LMD. However, the significantly increased late mortality in patients with LMD without prior CABG suggests that early revascularization should be considered in these patients.

Enhanced external counterpulsation therapy: significant clinical improvement without electrophysiologic remodeling

BACKGROUND

Enhanced external counterpulsation therapy (EECP), in addition to improving coronary flow and increasing the time to ischemia, noninvasively alters hemodynamics in patients with severe coronary artery disease (CAD). Other treatments that alter hemodynamics, for example, balloon valvuloplasty, left ventricular assist devices, and pharmacologic antagonism of the rennin-angiotensin system, promote electrophysiologic remodeling, as evidenced by alterations in the QT interval.

METHODS

We studied 28 patients who completed a 7-week, 35-hour session of EECP to assess whether such therapy would also result in electrophysiologic remodeling.

RESULTS

All patients had class II-III angina, imaging-proven ischemia, and severe, near-inoperable CAD. Of 28 patients, with a mean age 62 +/- 13 years (mean +/- SD), 78% were male, 46% diabetic, 82% hypertensive, 60% had undergone angioplasty, and 67% had undergone bypass surgery. The mean ejection fraction was 44% (range 25-60%). Following EECP, most patients (82%) had at least a one full class improvement in their anginal pattern. In most patients, there was substantial baseline conduction system disease present: a mean QRS of 105 +/- 19 ms. It is to be noted that there was no significant change in heart rate (HR), PR, QRS, or QT(c) intervals before and after EECP in either clinical responders or nonresponders. When analyzed by response to EECP, ejection fraction, or history of revascularization, there were still no detectable changes in ECG parameters (all P = NS).

CONCLUSIONS

While EECP remains an effective treatment for severe CAD, it does not prompt early electrical remodeling of the heart.

ACCELERATED REPERFUSION OF POORLY PERFUSED RETINAL AREAS IN CENTRAL RETINAL ARTERY OCCLUSION AND BRANCH RETINAL ARTERY OCCLUSION AFTER A SHORT TREATMENT WITH ENHANCED EXTERNAL COUNTERPULSATION

BACKGROUND

To date, no satisfactory therapy has become available for patients with acute central retinal artery occlusion (CRAO) or branch retinal artery occlusion (BRAO). Enhanced external counterpulsation (EECP) is a new noninvasive procedure that increases perfusion of inner organs. In the current study, the authors measured the impact of EECP on reperfusion in ischemic retinal tissue.

METHODS

In a prospective, randomized study, 20 patients with CRAO or BRAO were included. Ten patients were given hemodilution therapy and 2 hours of EECP, and 10 patients were given regular hemodilution therapy only. Quantification of changes in retinal perfusion was carried out by means of scanning laser Doppler flowmetry (in arbitrary units).

RESULTS

Enhanced external counterpulsation caused no observable adverse events. A significant increase in perfusion occurred immediately after EECP in the ischemic retinal areas (57 +/- 19 arbitrary units versus 99 +/- 14 arbitrary units). In contrast, no change was measured in the group not treated with EECP (83 +/- 19 arbitrary units versus 89 +/- 44 arbitrary units). Forty-eight hours later, a significant increase in perfusion could be shown in the ischemic retina of both groups, and no significant difference of perfusion was found between the two groups any longer.

CONCLUSION

The current study suggests that EECP could be a clinically useful and safe procedure in patients with CRAO or BRAO to accelerate recovery of perfusion in ischemic retinal areas.

A new treatment modality in heart failure enhanced external counterpulsation (EECP)

Heart failure remains a significant health problem in the United States and in the world. Despite a surfeit of recent diagnostic and therapeutic advances, patients with heart failure remain inadequately helped. The overwhelming need for new and better therapies continues to stimulate scientists to investigate new technologies. Over the past several years the use of enhanced external counterpulsation as a treatment for chronic angina has steadily increased. Recently, its potential role in heart failure management has been shown. We review the role of enhanced external counterpulsation in heart failure management as an emerging noninvasive outpatient therapy.

Enhanced external counterpulsation improves skin oxygenation and perfusion

BACKGROUND

Enhanced external counterpulsation (EECP) augments diastolic and reduces systolic blood pressures. Enhanced external counterpulsation has been shown to improve blood flow in various organ systems. Beneficial effects on skin perfusion might allow EECP to be used in patients with skin malperfusion problems. This study was performed to assess acute effects of EECP on superficial skin blood flow, transdermal oxygen and carbon dioxide pressures.

MATERIALS AND METHODS

We monitored heart rate, blood pressure, transdermal blood flow as well as oxygen and carbon dioxide pressures in 23 young, healthy persons (28 +/- 4 years) and 15 older patients (64 +/- 7 years) with coronary artery disease before, during and 3 min after 5 min EECP. Friedman test was used to compare the results of 90-s epochs before, during and after EECP. Significance was set at P < 0.05.

RESULTS

Enhanced external counterpulsation increased heart rate and mean blood pressure. During EECP, transdermal oxygen pressure and concentration of moving blood cells increased while transdermal carbon dioxide pressure and velocity of moving blood cells decreased significantly in both groups. After EECP, transdermal carbon dioxide pressure was still reduced while the other parameters returned to baseline values.

CONCLUSIONS

Improved skin oxygenation and carbon dioxide clearance during EECP seem to result from the increased concentration and reduced flow velocity, i.e. prolonged contact time, of erythrocytes. The increased concentration of moving blood cells and the decreased velocity of moving blood cells at both tested skin sites indicate peripheral vasodilatation.

Practicability and limitations of enhanced external counterpulsation as an additional treatment for angina

BACKGROUND

An increasing number of clinical studies indicates reduction of angina and myocardial ischemia by enhanced external counterpulsation (EECP) therapy. However, given the wide range of contraindications and the long duration of treatment, eligibility and practicality issues have not been addressed systematically.

HYPOTHESIS

Of all candidates for EECP (patients with drug-refractory angina without possibility of revascularization), the majority either have contraindications or have practical problems complying with the time demands that this therapy imposes. In the rest, EECP leads to satisfactory results.

METHODS

During 18 months, every consecutive patient with angina despite medical and interventional therapy was evaluated for EECP at one center. Treated patients underwent a bicycle exercise test and perfusion imaging before and after the standard course of 35 h of EECP. In addition, patients were asked about frequency of angina and nitroglycerin usage before and after EECP, and all patients filled out a final questionnaire 1 year after the end of therapy.

RESULTS

Overall, 48 patients were considered candidates for EECP. Of these, 24 were excluded for medical reasons: poor ejection fraction (4), peripheral artery disease (4), anticoagulation (4), and atrial fibrillation (3). Eight further patients declined EECP for lack of time or accommodation. Another 3 of the 16 remaining patients dropped out because of side effects. In the 13 patients who finished the treatment course, weekly anginal episodes were reduced by 48% (p < 0.05), on-demand nitroglycerin puffs were reduced by 51% (p < 0.05), work capacity was improved by 22% (p < 0.05), and the number of reversible perfusion defects in perfusion scans decreased nonsignificantly (-28%). However, 4 of 13 treated patients determined 1 year later that the detriment of loss of time exceeded the benefits of EECP.

CONCLUSION

Similar to previous reports, our study confirms the reduction of angina and improvement of work capacity after EECP. However, using established contraindications, approximately two-thirds of patients considered to be candidates had to be excluded, and one-third of the treated patients regarded EECP therapy retrospectively as too time consuming.

Analysis of baseline factors associated with reduction in chest pain in patients with angina pectoris treated by enhanced external counterpulsation

Data from the International Enhanced External Counterpulsation (EECP) Patient Registry were analyzed to determine which patient characteristics influence improvement in angina class with EECP treatment. Patients with severely disabling angina at baseline, men, and those without a history of smoking are more likely to improve their angina class after EECP, whereas those with diabetes mellitus, prior bypass surgery, and heart failure were less likely to benefit.

Enhanced external counterpulsation for refractory angina pectoris

Enhanced external counterpulsation (EECP) is a non-invasive outpatient treatment used for angina pectoris. In patients with intractable angina refractory to aggressive surgical and medical treatment, several novel strategies are considered including EECP, transmural laser revascularisation, and spinal cord stimulation. EECP produces an acute haemodynamic effect that is presumed to be similar to that produced by the invasive intra-aortic balloon pump. By applying a series of compressive cuffs sequentially from the calves to the thigh muscles upon diastole and rapidly deflating the cuffs in early systole, an increase in diastolic and decrease in systolic pressure is created. Although data indicate improvement in angina in patients undergoing EECP, the role of EECP in the treatment of angina pectoris has not yet been well defined. At present, EECP use should be limited to patients with debilitating (functional class III and IV) refractory angina pectoris who are not candidates for revascularisation, are symptomatic despite being on maximal antianginal pharmacotherapy, and have no contraindications to EECP use.

Changes of cerebral blood flow velocities during enhanced external counterpulsation

OBJECTIVES

Intra-aortic counterpulsation is the most frequently used cardiac assist device. However, there are only few studies of the effects of counterpulsation on cerebral blood flow and these report conflicting outcomes. The new enhanced external counterpulsation (EECP) technique reproduces non-invasively the effects of intra-aortic counterpulsation. In this study, we evaluated effects of EECP on blood pressure (BP) and on cerebral flow velocity (CBFV).

SUBJECTS AND METHODS

Twenty-three healthy controls and 15 atherosclerotic patients each underwent a 5-min session of EECP. Before, during and after EECP we monitored heart rate, beat-to-beat radial artery BP and CBFV.

RESULTS

EECP induced a second increase in BP and CBFV during diastole with a significant increase of mean BP and a decrease of systolic BP in patients and controls. Mean CBFV increased in both groups during the first 5 s of EECP. After 3 min of EECP, diastolic CBFV was still higher than at baseline, but systolic CBVF was lower than at baseline; mean CBFV was as low as before EECP in the patients and lower than the baseline values in the controls. Three minutes after ending EECP, mean and systolic BP were lower in the patients than the corresponding baseline values. Otherwise, CBFV and BP values did not differ from baseline in patients and controls.

CONCLUSION

Cerebral autoregulation ensures the constancy of cerebral blood flow even though EECP creates marked systemic changes. In the patients, the decrease of BP after EECP with maintained CBFV indicates an improved BPCBFV relation and a more economic autoregulation.

Enhanced external counterpulsation in the management of angina in the elderly

This study was undertaken to determine whether enhanced external counterpulsation is a safe and effective treatment for angina in octogenarians. In this prospective observational study, demographic and clinical outcome data on patients consecutively enrolled in the International EECP Patient Registry was examined. Of the 3037 patients analyzed, 249 (8%) were >/=80 years old. Octogenarians were more likely to be female and have a history of congestive heart failure (41% vs. 29%; p<0.001). They were less likely to have had previous revascularization. Fewer patients in the octogenarian group (76% vs. 84%; p<0.01) completed a course of treatment. Of those octogenarian patients who completed treatment, 76% reported a reduction in angina and quality of life improved significantly. Adverse events related to treatment were low. At 6-month follow-up, 81% reported maintenance of angina improvement. Thus, enhanced external counterpulsation is a low-risk intervention that offers octogenarians the ability to return to more normal activity and a better quality of life.

Left ventricular systolic unloading and augmentation of intracoronary pressure and Doppler flow during enhanced external counterpulsation

BACKGROUND

Enhanced external counterpulsation (EECP) is a noninvasive, pneumatic technique that provides beneficial effects for patients with chronic, symptomatic angina pectoris. However, the physiological effects of EECP have not been studied directly. We examined intracoronary and left ventricular hemodynamics in the cardiac catheterization laboratory during EECP.

METHODS AND RESULTS

Ten patients referred for diagnostic evaluation underwent left heart catheterization and coronary angiography from the radial artery. At baseline and then during EECP, central aortic pressure, intracoronary pressure, and intracoronary Doppler flow velocity were measured using a coronary catheter, a sensor-tipped high-fidelity pressure guidewire, and a Doppler flow guidewire, respectively. Similar to changes in aortic pressure, EECP resulted in a dramatic increase in diastolic (71+/-10 mm Hg at baseline to 137+/-21 mm Hg during EECP; +93%; P<0.0001) and mean intracoronary pressures (88+/-9 to 102+/-16 mm Hg; +16%; P=0.006) with a decrease in systolic pressure (116+/-20 to 99+/-26 mm Hg; -15%; P=0.002). The intracoronary Doppler measure of average peak velocity increased from 11+/-5 cm/s at baseline to 23+/-5 cm/s during EECP (+109%; P=0.001). The TIMI frame count, a quantitative angiographic measure of coronary flow, showed a 28% increase in coronary flow during EECP compared with baseline (P=0.001).

CONCLUSIONS

EECP unequivocally and significantly increases diastolic and mean pressures and reduces systolic pressure in the central aorta and the coronary artery. Coronary artery flow, determined by both Doppler and angiographic techniques, is increased during EECP. The combined effects of systolic unloading and increased coronary perfusion pressure provide evidence that EECP may serve as a potential mechanical assist device.