Continuous Aortic Flow Augmentation

Single lung retrieval from a donor supported by a left ventricular assist device

The number of patients who need cardiac support with a left ventricular assist device (LVAD) has increased over the last decade. However, the number of reports of organ retrieval from donors with an LVAD is still small. Successful lung retrieval for single lung transplantation was performed from a donor on LVAD support. This required special care not to injure the heart, great vessels, and the device, particularly the outflow conduit, because of significant conglutination around the device. A right single lung transplantation was performed successfully, with no postoperative complications. This means that patients on an LVAD could be potential donors for lung transplantation.

New therapeutic options in heart failure. What's on the horizon? An overview

Heart failure is a complex clinical syndrome responsible for high morbidity and mortality in the world. Despite advances in the management of heart failure, the prognosis of these patients remains poor and there is a critical need for new treatment strategies improving the clinical outcomes. New approaches in heart failure therapies target cellular mechanisms, as well as mechanical and structural aspects of heart failure that are not addressed by recent therapies. These include abnormalities in molecular mechanisms, electrical conduction and ventricular remodeling. This review presents the pathophysiological basis, mechanisms of action and available clinical efficacy and safety data of drugs and mechanical therapies that are currently under development.

Neurohumoral response and clinical effectiveness of continuous aortic flow augmentation in patients with decompensated heart failure

The increasing number of patients with progressive or exacerbated heart failure that is refractory to medical treatment necessitates the development of innovative cardiac assist devices. The aim of this study was to investigate whether a new percutaneously inserted system, which allows continuous aortic flow augmentation (CAFA), could be shown to be clinically effective with neurohormonal benefit in patients admitted with decompensated heart failure. Patients with exacerbations of chronic heart failure were recruited for the study. A percutaneous circulation assist device (Cancion system) promoting CAFA was implanted for up to 4 days in each patient. Clinical improvement was evaluated by measuring the clinical status according to the New York Heart Association (NYHA) classification and biochemical parameters including troponin and B-type natriuretic peptide (BNP) as markers of cardiac necrosis and cardiac overload; these parameters were measured before, during, and after CAFA treatment. The decrease in BNP was determined after implantation, reaching, on average, a maximum decrease of 57% at 72 h (P = 0.04). The neurohumoral response remained significant (P < 0.05) up to 120 h after implantation, with a decrease in BNP levels of 37%, on average, compared to baseline values. Troponin I did not show any significant change during mechanical assistance (P > 0.2). All patients had improved clinical status according to the NYHA classification, and the improvement lasted for more than 1 week. Percutaneous heart-assist devices promoting CAFA offer clinical improvement and a neurohumoral response, with a significant BNP reduction in severe exacerbation of chronic heart failure that is refractory to medical treatment.

Acute left ventricular unloading in dogs with chronic heart failure: continuous aortic flow augmentation versus intra-aortic balloon pumping

BACKGROUND

Continuous aortic flow augmentation (CAFA) therapy with the Cancion System (Orqis Medical, Inc) was shown to effectively unload the left ventricle in dogs with chronic heart failure (HF). This study compared the extent of acute left ventricular (LV) unloading elicited by CAFA to that elicited by intra-aortic balloon counterpulsation (IABP) in normotensive dogs with coronary microembolization-induced HF.

METHODS AND RESULTS

Seven HF dogs were studied with both CAFA and IABP in random order and 1 week apart. In both instances, active therapy was maintained for 4 hours. The Cancion system was positioned using a dual femoral approach configuration with a constant pump flow of 250 mL/min. In all dogs and with both devices, LV end-diastolic pressure (EDP), LV end-systolic volume (ESV), and LV ejection fraction (EF) were measured at baseline and at 2 and 4 hours after instituting CAFA or IABP. Plasma samples obtained at the end of 4 hours of therapy were used to measure a host of circulating biomarkers that included neurohormones, cytokines, and A-type and B-type natriuretic peptides. IABP had no significant effects on LVEDP, LVESV, and LVEF. In contrast, CAFA significantly decreased LVEDP and LVESV and increased LVEF. Compared with IABP, CAFA was accompanied by significant improvements in circulating levels of neurohormones, cytokines, and natriuretic peptides.

CONCLUSIONS

The results indicate that CAFA is more effective than IABP in achieving acute global LV unloading in dogs with chronic HF not complicated by ongoing myocardial ischemia or cardiogenic shock.

A control system for rotary blood pumps based on suction detection

A control system for rotary ventricular assist devices was developed to automatically regulate the pumping speed of the device to avoid ventricular suction. The control system comprises a suction detector and a fuzzy logic controller (FLC). The suction detector can correctly classify pump flow patterns, using a discriminant analysis (DA) model that combines several indices derived from the pump flow signal, to classify the pump status as one of the following: no suction (NS), moderate suction (MS), and severe suction (SS). The discriminant scores, which are the output of the suction detector, were used as inputs to the FLC. Based on this information, the controller updates pump speed, providing adequate flow and pressure perfusion to the patient. The performance of the control system was tested in simulations over a wide range of physiological conditions, including hypertension, exercise, and strenuous exercising for healthy, sick, and very sick hearts, using a lumped parameter model of the circulatory system coupled with a left ventricular assist device. The controller was able to maintain cardiac output and mean arterial pressure within acceptable physiologic ranges, while avoiding suction, demonstrating the feasibility of the proposed control system.

Mechanical circulatory support devices for acute heart failure syndromes: considerations for clinical trial design

Mechanical circulatory support (MCS) devices are a guideline-recommended treatment option for a small subset of advanced heart failure patients. MCS has the potential to become more prominent in the management of Acute Heart Failure Syndromes (AHFS) as device technology advances and as clinical trials consistently discover neutral or harmful effects with pharmacologic therapies hypothesized to be beneficial in this population. While it is now possible to identify AHFS patients who are at high risk of death, the therapeutic options available to improve their long-term outcomes are limited. MCS therapy in this population offers a "bridge to recovery" strategy; these patients may have viable myocardium that responds favorably to the influence of MCS on neurohormones, cytokines, and/or reverse remodeling. Patients at high risk for mortality who have a substantial likelihood of benefiting from MCS can be easily identified using standard clinical criteria developed from large observational databases. MCS technology is rapidly evolving, and risks related to implantation are declining. It is evident that rigorous clinical trial testing of the potential risks, benefits, and economic implications of MCS in patients with AHFS will need to be conducted before the "routine" application of this aggressive therapy. This paper examines the rationale for conducting trials of MCS devices in patients with AHFS, and it explores considerations for patient selection and appropriate endpoints. This manuscript was generated from discussions on this issue during the third international meeting of the International Working Group on AHFS held in Washington, DC, April 8-9, 2006.

New strategies for surgical management of ischemic cardiomyopathy

Ischemic cardiomyopathy affects an estimated 3 million people in the USA and is the most common cause of heart failure. Traditional operations have included heart transplantation, myocardial revascularization, mitral valve repair, left ventricular reconstruction, first-generation left ventricular assist devices and cardiac resynchronization therapy. These operations have become safer in recent times, due to improved technologies. Current technologies and surgical approaches can benefit a significant number of patients. However, there remains a large group of patients in whom traditional approaches can not be offered. Newer generation ventricular assist devices, passive ventricular restraint devices and cellular-based therapies (including skeletal- and bone marrow-derived stem cells) have the potential to be more universal in their applications. Ongoing investigations with each of these modalities will allow surgeons to offer treatment to patients who are not considered surgical candidates at this time.

Newer mechanical devices in the management of acute heart failure

Heart Failure is the only cardiovascular disease diagnosis increasing in prevalence in the United States. Currently there are more than 5 million people diagnosed with heart failure in the United States and that population is increasing exponentially. Clinical trials in advanced pharmacological therapies have shown a significant value in reducing the morbidity and mortality of the disease process. Nevertheless, many patients who are optimally treated with drug therapy continue to progress from asymptomatic left ventricular dysfunction to symptomatic and then end-stage heart failure. Beyond drug therapy, devices have begun to make a significant impact on symptoms and clinical outcomes in patients, particularly those with more advanced forms of heart failure. New technologies being investigated include destination and bridge LV assist devices. Due to the invasive nature of these devices a new generation of "less invasive" percutaneous devices are now being studied. These new generation devices offer the promise of improved LV function and an enhanced neurohormonal profile for the failing ventricle, thus improving the quality of life in the ever-burgeoning heart failure population.

Percutaneous mechanical devices in the management of decompensated heart failure

Heart failure is the only cardiovascular disease diagnosis increasing in prevalence in the United States. A number of drugs have been shown to reduce morbidity and mortality in patients with chronic heart failure. Despite these advances, the frequency of hospitalization for heart failure has continued to increase, and clinical trial data are lacking in demonstrable benefit of drug therapy for patients hospitalized with acute, decompensated heart failure. A number of percutaneous devices have been developed and are in various stages of investigation and use to improve symptoms and clinical outcomes in patients hospitalized with heart failure. These include "add-on" devices, such as continuous aortic flow augmentation and ultrafiltration devices, and "rescue" devices to be used in patients who are rapidly deteriorating despite medical therapy. In addition to the intra-aortic balloon pump, newer approaches include percutaneous ventricular assist devices that are available for short-term use to stabilize patients until recovery can occur or as "bridges" to longer-term assist or cardiac transplantation. In the coming years, expanded clinical investigation is likely to explore the potential for devices to normalize underlying cardiac function and thereby improve long-term clinical outcomes.

Percutaneous continuous aortic flow augmentation for cardiac recovery in a chronic heart failure patient with peripheral vascular disease

Peripheral vascular disease is an obstacle to the use of continuous aortic flow augmentation (CAFA). The authors used CAFA in a patient with a 50% stenosis of the left iliac artery. Five hours after initiating therapy, flow rates dropped from 1.47 L/min to 0.2 L/min, possibly due to obstruction around the inflow cannula near the site of the iliac artery stenosis. Flow was stabilized by adequate fluid infusion and successfully restored by slightly withdrawing the tip of the inflow catheter. This finding suggests that peripheral vascular disease is a relative-not an absolute-contraindication for CAFA, but requires close monitoring of flow during CAFA therapy.