Percutaneous Mechanical Support for the Failing Right Heart

The various perioperative issues of structural heart diseases and cardiogenic shock

Up to 20 % of patients presenting with acute heart failure and cardiogenic shock have a structural etiology. Despite efforts in timely management, mortality rates remain alarmingly high, ranging from 50 % to 80 %. Surgical intervention is often the definitive treatment for structural heart disease; however, many patients are considered high risk or unsuitable candidates for such procedures. Consequently, there has been a paradigm shift towards the development of novel percutaneous management strategies and temporizing interventions. This article aims to provide a comprehensive review of the pathophysiology of valvular and structural heart conditions presenting in cardiogenic shock, focusing on the evolving landscape of mechanical circulatory support devices and other management modalities.

Use of a Percutaneous Right Ventricular Assist Device to Manage Right Ventricular Failure in Inferior STEMIs

Acute right heart failure is a complication of inferior ST-elevation myocardial infarctions. Given the further hemodynamic instability that results from right-sided failure, a treatment option is needed to help bridge toward cardiac recovery. We present a case of using a right ventricular assist device in a patient who had marked improvement in cardiac function after an instance of acute right heart failure.

Pre-Existing Right Ventricular Dysfunction as an Independent Risk Factor for Post Intubation Cardiac Arrest and Hemodynamic Instability in Critically Ill Patients: A Retrospective Observational Study

BACKGROUND

Post intubation cardiac arrest and hemodynamic instability are serious adverse events encountered in critically ill patients. The association of pre-existing right ventricular (RV) dysfunction with post intubation cardiac arrest and hemodynamic instability in critically ill patients is unknown.

METHODS

This is a retrospective matched cohort study of adult critically ill patients who underwent intubation from July 2016 to December 2019. The study was conducted at a quaternary medical center in Houston, Texas. A total of 340 critically ill patients who underwent intubation in the intensive care units, wards, and the emergency room were included. The study cohort was categorized into 4 groups based on the pre-existing RV function: normal function, mild dysfunction, moderate dysfunction, and severe dysfunction. Cardiac arrest and/or hemodynamic instability within one hour post intubation were the primary study outcomes. Secondary outcomes included in hospital and 60-day mortality.

RESULTS

Study patients were of mean age of 61.95 ± 14.28 years, including 132 (39%) females and 208 (61%) males. The primary outcomes were significantly worse in mild, moderate, and severe RV dysfunction groups compared to the normal RV function group (34.12%-P = 0.014, 47.06%-P < 0.001, 51.67%-P < 0.001, vs. 17.56%). In a multivariable logistic regression analysis, pre-existing moderate (OR = 2.65, P = 0.013) and severe RV dysfunction groups (OR = 2.66, P = 0.015) were associated with statistically significant higher cardiac arrest and hemodynamic instability post intubation. Pre-existing severe RV dysfunction was associated with statistically significant higher in hospital mortality (62.35%-P < 0.001). The multivariable Cox-regression analysis showed that pre-existing severe RV dysfunction was associated with a statistically significant higher 60-day mortality (HR = 2.57, P = 0.001).

CONCLUSIONS

Pre-existing moderate and severe RV dysfunctions were independently associated with significantly higher cardiac arrest and/or hemodynamic instability post intubation in critically ill patients. Pre-existing RV function may serve as a mortality predictor in critically ill patients undergoing endotracheal intubation.

Temporary Right Ventricular Assist Device Support for Acute Right Heart Failure: A Single-Center Experience

INTRODUCTION

Severe right ventricular (RV) failure is associated with significant morbidity and mortality. Although right ventricular assist devices (RVADs) are increasingly used for refractory RV failure, there is limited data on their short- and long-term outcomes. Therefore, we undertook this study to better understand our experience with temporary RVADs.

METHODS

We conducted a retrospective review of all RVADS performed from 2017 to 2021. Patients supported with surgical RVADs, the Protek Duo device, and the Impella RP device were included. Patients were stratified by the type of RVAD and by etiology of RV failure. Survival was assessed by the Kaplan-Meier method and multivariable Cox proportional hazards regression models.

RESULTS

From 2017 to 2021, 42 patients underwent RVAD implantation: 32 with a Protek Duo, 6 with an Impella RP, and 4 with a surgical RVAD. Majority of patients were already supported with an alternate form of mechanical support. Most patients had impaired renal function, decreased hepatic function, and lactic acidosis at the time of cannulation. The median duration of RVAD support was 8.5 [5-19] d. Survival to decannulation was 68.4%, to discharge was 47.4%, and to 1-y was 40.2%. Multivariable analysis identified elevated total bilirubin levels to be associated with 30-d mortality while increased hemoglobin levels were protective. After RVAD cannulation, the median number of pressors and inotropes was lower (P < 0.01) and the lactic acidosis was less (P < 0.01).

CONCLUSIONS

In conclusion, RVAD support is associated with lower lactate levels, and decreased number of vasoactive medications, but is associated with significant morbidity and mortality.

Management of Post-Myocardial Infarction Right Ventricular Failure

Right ventricular failure (RVF) due to an acute myocardial infarction (MI) has been associated with high morbidity and mortality. Initial treatment is guided by early recognition and prompt revascularization. Current management of post-MI RVF is built upon expert consensus and is also informed by RVF from other etiologies, including massive pulmonary embolism, left ventricular assist device-associated right ventricular dysfunction, postcardiotomy shock, etc.; this speaks to the limited data available on the specific management of RVF in acute MI. The goal of this review is to discuss the current literature on the pathophysiology, general management considerations, interventional management, hemodynamic monitoring, medical management, and mechanical circulatory support of MI-induced RVF.

Impella RP for Patients with Acute Right Ventricular Failure and Cardiogenic Shock: A Subanalysis from the IMP-IT Registry

The use of percutaneous right ventricular assist devices (pRVADs) to support patients with right ventricular (RV)-predominant cardiogenic shock (CS) refractory to optimal medical therapy is increasing progressively, and the Impella RP is the first FDA-approved pRVAD in such a clinical scenario. The aim of the present study is to report the outcomes of patients treated with Impella RP in the IMP-IT (IMPella Mechanical Circulatory Support Device in Italy) registry, a multicenter registry that evaluated the trends in use and clinical outcomes of the Impella in the setting of CS and high-risk percutaneous coronary intervention in Italy. A total of 15 patients who received Impella RP were enrolled. In 40% of the patients, the main cause was ST-segment elevation myocardial infarction. A total of 40% of patients required biventricular support with a left Impella. Device-related complications were reported in 46.7% of patients. Overall, the in-hospital mortality was 46.7%, whereas the one-year mortality was 53.3%. The composite rate of all-cause death, heart failure (HF) hospitalization, left ventricular assist device (LVAD) and heart transplant at one year was 60%. The Impella RP has favorable survival outcomes in RV-predominant cardiogenic shock. However, the device-related complications are frequent and should be carefully weighed when considering escalation to Impella RP.

Mechanical Circulatory Support for Right Ventricular Failure

Right ventricular (RV) failure is associated with significant morbidity and mortality, with in-hospital mortality rates estimated as high as 70–75%. RV failure may occur following cardiac surgery in conjunction with left ventricular failure, or may be isolated in certain circumstances, such as inferior MI with RV infarction, pulmonary embolism or following left ventricular assist device placement. Medical management includes volume optimisation and inotropic and vasopressor support, and a subset of patients may benefit from mechanical circulatory support for persistent RV failure. Increasingly, percutaneous and surgical mechanical support devices are being used for RV failure. Devices for isolated RV support include percutaneous options, such as micro-axial flow pumps and extracorporeal centrifugal flow RV assist devices, surgically implanted RV assist devices and veno-arterial extracorporeal membrane oxygenation. In this review, the authors discuss the indications, candidate selection, strategies and outcomes of mechanical circulatory support for RV failure.

Comprehensive evaluation of Impella RP® in right ventricular failure

Right ventricular failure has a high morbidity and mortality in patients suffering from advanced heart failure, pulmonary hypertension, acute myocardial infarction after cardiac surgery and in left ventricular assist device patients. The Impella RP^® catheter is a mechanical circulatory device, positioned from a venous femoral percutaneous access and passing through the tricuspid and pulmonary valves, reaches the pulmonary artery. Impella RP (Abiomed Inc., MA, USA) acts as a direct right ventricle bypass and it provides a flow up to 4.4 liters per minute, unloading the right ventricle. The main contraindications are: thrombi in the vena cava, right atrium and ventricle and pulmonary artery; mechanical tricuspid or pulmonary prostheses. In this review, the principles of operations, clinical applications and results of Impella RP are summarized and evaluated.

Clinical use of percutaneous mechanical circulatory assistance in a patient with end-stage right-sided heart failure and massive tricuspid insufficiency due to congenital heart disease: first-in-the-world case report

Background

Due to improvement in the management of patients with congenital heart disease (CHD), the likelihood of their survival to adulthood is increasing. A relevant population suffers end-stage right ventricular failure (RVF) in their 3rd–4th decade of life. Hence, heart transplantation is still gold standard of treatment of end-stage heart failure, mechanical circulatory assistance has become a valuable tool in the bridging to heart transplant or definitive therapy. Use of implantable short-term or long-term devices is reported by others. However, within this clinical context, presence of significant tricuspid regurgitation (TR) or CHD is used as exclusion criteria for insertion of a percutaneous right ventricular circulatory support.

Case summary

We described a 36-year-old patient diagnosed with Ebstein's anomaly and severe TR who is admitted to hospital due to RVF refractory to standard medical treatment. After case presentation to the heart team, an Impella RP device insertion was scheduled, in spite of the presence of TR or CHD after evaluation of pulmonary valve competency and 3D reconstruction with virtual device implantation. During support, the patient improved clinically and haemodynamically. Due to device displacement to the right ventricle, it was bedside explanted after 30 days of support. After mechanical unloading during 30 days patients’ right ventricle recovered partially, permitting patient to improve his functional class.

Discussion

Although TR and CHD are exclusion criteria for the implantation of the Impella RP device, we report clinical experience in patient with Ebstein's anomaly and severe TR supported with percutaneous device as bridge to heart transplantation during 30 days.

A single healthcare experience with Impella RP

OBJECTIVES

To understand the predictors of survival and indications for Impella RP in a single healthcare experience.

BACKGROUND

The Impella RP can be used to temporarily support patients with right ventricular (RV) dysfunction after left ventricular assist device (LVAD) placement or myocardial infarction (MI). However, recent postmarket approval data have raised concerns of higher than expected mortality with this device.

METHODS

A retrospective chart review and analysis of all patients that underwent Impella RP placement in the Emory Healthcare system between January 2016 and December 2018 were performed. Patients were classified according to the indication.

RESULTS

A total of 39 patients underwent Impella RP placement. Six patients were post-LVAD, 9 were implanted for massive pulmonary embolism with persistent shock, 8 for postcardiac surgery RV failure (non-LVAD), 11 for RV failure post-MI, and 5 for new or worsening nonischemic cardiomyopathy. The worst survival was noted in MI-related cardiogenic shock group and in patients who presented with cardiac arrest (3/12). All observed deaths were due to persistent refractory shock. There was no device related death. Survival improved during the last year of experience compared to the first 2 years.

CONCLUSION

This study supports the selective use of the Impella RP, with a higher than national reported survival rate (49% vs. 28.6%). Indication appears to be an important factor determining survival.

A Dual-Lumen Percutaneous Cannula for Managing Refractory Right Ventricular Failure

A right ventricular assist device (RVAD) using a dual-lumen percutaneous cannula inserted through the right internal jugular vein (IJV) might improve weaning in patients with refractory right ventricular (RV) failure. However, the reported experience with this cannula is limited. We reviewed the records of all patients receiving RVAD support with this new dual-lumen cannula at our institution between April 2017 and February 2019. We recorded data on weaning, mortality, and device-specific complications. We compared outcomes among three subgroups based on the indications for RVAD support (postcardiotomy, cardiogenic shock, and primary respiratory failure) and against similar results in the literature. Mean (standard deviation [SD]) age of the 40 patients (29 men) was 53 (15.5) years. Indications for implantation were postcardiotomy support in 18 patients, cardiogenic shock in 12, and respiratory failure in 10. In all, 17 (94%) patients in the postcardiotomy group were weaned from RVAD support, five (42%) in the cardiogenic shock group, and seven (70%) in the respiratory failure group, overall higher than those reported in the literature (49% to 59%) for surgically placed RVADs. Whereas published in-hospital mortality rates range from 42% to 50% for surgically placed RVADs and from 41% to 50% for RVADs with percutaneous cannulas implanted through the right IJV, mortality was 11%, 58%, and 40% in our subgroups, respectively. There were no major device-related complications. This percutaneous dual-lumen cannula appears to be safe and effective for managing refractory RV failure, with improved weaning and mortality profile, and with limited device-specific adverse events.

Anaerobic Bacteremias in Left Ventricular Assist Devices and Advanced Heart Failure

Left ventricular assisted devices (LVADs) have revolutionized the treatment of advanced heart failure, providing meaningful increases in survival, functional capacity, and quality of life. There are two categories of LVADs patients: (1) bridge-to-transplant and (2) destination therapy. Advanced heart failure and destination LVADs often carry a poor prognosis. The overall 1-year mortality rate remains as high as 30%. LVAD-specific infections, LVAD-related infections, and non-LVAD-related infections represent important emerging clinical problems in this setting. With an incidence ranging from 30 to 50%, these lead to high rates of hospitalization, morbidity, and mortality. Bacteremias caused by anaerobic pathogens in patients with LVAD are underreported. Herein, we describe the microbiological findings, treatment, and clinical outcome of four patients with LVADs and advanced heart failure with anaerobic bacteremias. Fusobacterium species was the most frequent etiological agent. Most patients had a relatively favorable short-term outcome with survival rates of 100% at 30 days and of 50% at 90 days. However, due to other multiple long-term complications, overall mortality remains at 50% during the first year and increases to 75% beyond the first year. Anaerobic bacteremia sources included the oral cavity from odontogenic infections and aspiration pneumonia. Anaerobic bacteremia constitutes an unfavorable mortality prognostic factor in patients with destination LVADs. We recommend implementing preventive strategies with a comprehensive dental care evaluation in patients with LVADs and advanced heart failure.

Hemodynamics of Cardiogenic Shock

Cardiogenic shock (CS) represents an advanced state of morbidity along the pathophysiologic pathway of end-organ hypoperfusion caused by reduced cardiac output and blood pressure. Acute coronary syndromes remain the most common cause of CS. The spectrum of hypoperfusion states caused by low cardiac output ranges from pre-CS to refractory CS and can be characterized by an array of hemodynamic parameters. This review provides the foundation for a hemodynamic understanding of CS including the use of hemodynamic monitoring for diagnosis and treatment, the cardiac and vascular determinants of CS, and a hemodynamic approach to risk stratification and management of CS.

PERKAT RV: first in vivo data of a novel right heart assist device

AIMS

Mechanical right ventricular (RV) support offers a treatment option for critically ill patients with RV failure (RVF). We developed an assist device for rapid percutaneous implantation. The aim of the present study was to investigate the implantation procedure, haemodynamic performance and possible side effects of the novel right ventricular assist device - PERKAT RV - in an animal model.

METHODS AND RESULTS

The PERkutane KATheterpumptechnologie RV (PERKAT RV) device consists of a nitinol chamber covered by foil containing inflow valves. An outlet tube is attached to its distal part. The system is designed for 18 Fr percutaneous implantation. The chamber is unfolded in the inferior vena cava while the outlet tube bypasses the right heart with the tip in the pulmonary trunk. An IABP balloon is placed inside. Balloon deflation generates blood flow into the chamber; during inflation, blood is guided into the pulmonary arteries. Acute RVF was induced by venous injection of Sephadex in seven sheep for evaluation of the device. The PERKAT RV was able to improve haemodynamics immediately generating a median increase in cardiac output of 59%. Longer pump support was evaluated in a second study. Four sheep were supported for eight hours without any problems.

CONCLUSIONS

The percutaneous implantation and explantation of the PERKAT RV device was possible in the designed way. The sheep studies proved beneficial haemodynamic effects in acute RVF. The system offers easy and safe treatment in acute RVF.

Percutaneous biventricular Impella support in therapy-refractory cardiogenic shock

INTRODUCTION

Percutaneous mechanical circulatory support systems have increasingly been adopted as a bail out strategy in patients with cardiogenic shock. Since studies showed mostly mixed results, however, the use of support systems remains a case by case decision.

CASE

Here, we report on a case of therapy-refractory cardiogenic shock due to acute myocardial infarction treated with percutaneous right and left ventricular assist devices (Impella RP and CP).

CONCLUSION

Due to myocardial stunning, even patients with fulminant cardiogenic shock have the potential for full recovery. In the present case, we demonstrate the feasibility of biventricular Impella support in therapy-refractory cardiogenic shock facilitating bridge to recovery.

Mechanical circulatory support for acute right ventricular failure in the setting of pulmonary embolism

BACKGROUND

Right ventricular (RV) failure due to pulmonary embolism (PE) increases morbidity and mortality and contributes to prolonged hospital length of stay and higher costs of care. RV mechanical circulatory support (MCS) including Impella RP devices have been increasingly used in hemodynamically compromised PE patients who are refractory to intravascular volume expansion and inotropic therapy. However, effectiveness and safety of Impella RP, in hemodynamically unstable PE patients is unknown.

METHODS

We included consecutive patients who presented to Detroit Medical Center between November 3, 2015 and October 2, 2017 with acute PE and had evidence of hemodynamic compromise indicating Impella RP.

RESULTS

Total of five cases were identified. All patients met the shock definition due to massive or submassive PE and therefore received Impella RP on admission. Cardiac index was improved from mean of 1.69/min/m^2, (0.88-2.15 L/min/m² ), to 2.5 L/min/m² (range 1.88-3.4), after 24 h of treatment. Similarly, mean heart rate reduced to 92 beats per minute (79-105), and mean systolic blood pressure increased to 140 mmHg (115-179). No significant changes were found in renal function, hemoglobin and platelets level during device use. One patient experienced hemoglobin drop from 13.7 to 7.3 g/dL but did not require blood transfusion. All patients survived to discharge.

CONCLUSION

In patients with PE and RV shock, Impella RP device resulted in immediate hemodynamic benefit with reversal of shock and favorable survival to discharge.

Successful surgical employment of Impella recovery system for right ventricular failure after previous aortic valve replacement

A 58-year-old woman underwent aortic valve replacement. On the second postoperative day the patient referred a sharply chest pain, and an emergent coronary angiography revealed total occlusion of the right coronary artery. An intra-aortic ballon pump was placed and the patient underwent emergent off-pump coronary revascularization of the right coronary artery. Five hours later, due to unstable hemodynamic the extracorporeal membrane oxygenation was implanted without improvement of the right ventricular (RV) function. Then we decided to implant the Impella Right Direct (RD). After 9 days of Impella’s insertion the RV was recovered and the device was successfully explanted. After 16 days of Impella explanted the patient was discharged. This case suggest that implantation of Impella RD is clinically feasible, associated with hemodynamic improvement, and facilitate successful bridge-to-recovery in patients with post-cardiotomy RV failure due to myocardial infarction unresponsive to coronary artery bypass grafting, maximal medical therapy, contrapulsation and extracorporeal membrane oxygenation.

Cardiac passive-aggressive behavior? The right ventricle in patients with a left ventricular assist device

INTRODUCTION

Right ventricular failure (RVF) affects up to 50% of patients post-left ventricular assist device (LVAD) implantation, and carries significant morbidity and mortality. There is no widely-used long-term mechanical support option for the right ventricle, thus early identification, prevention and medical treatment of RVF is of the upmost importance. Areas covered: A PubMed search was first completed searching 'Right ventricular failure post-LVAD' which yielded 152 results, and a subsequent search was performed under 'RV mechanical support' which yielded 374 results, and was filtered to 'humans' and literature written in English, generating 219 results. We focused this research on pre-operative risk factors identified in the literature for developing RVF-post LVAD implantation, and the medical and surgical treatment options for RVF, including mechanical treatment options. Expert commentary: There is little consensus on pre-operative risk factors that reliably predict RVF post-LVAD implantation. Large prospective randomized trials would help clarify indications for specific medical and surgical therapy. We gather this knowledge in the present article and describe the main RVF remediation modalities. Surgeons and anesthesiologists should help prevent and have a low threshold for initiating supportive treatment for RVF, which may include increasingly invasive therapies up to long-term mechanical RV support.

Mechanical circulatory assist devices: a primer for critical care and emergency physicians

Mechanical circulatory assist devices are now commonly used in the treatment of severe heart failure as bridges to cardiac transplant, as destination therapy for patients who are not transplant candidates, and as bridges to recovery and “decision-making”. These devices, which can be used to support the left or right ventricles or both, restore circulation to the tissues, thereby improving organ function. Left ventricular assist devices (LVADs) are the most common support devices. To care for patients with these devices, health care providers in emergency departments (EDs) and intensive care units (ICUs) need to understand the physiology of the devices, the vocabulary of mechanical support, the types of complications patients may have, diagnostic techniques, and decision-making regarding treatment. Patients with LVADs who come to the ED or are admitted to the ICU usually have nonspecific clinical symptoms, most commonly shortness of breath, hypotension, anemia, chest pain, syncope, hemoptysis, gastrointestinal bleeding, jaundice, fever, oliguria and hematuria, altered mental status, headache, seizure, and back pain. Other patients are seen for cardiac arrest, psychiatric issues, sequelae of noncardiac surgery, and trauma. Although most patients have LVADs, some may have biventricular support devices or total artificial hearts. Involving a team of cardiac surgeons, perfusion experts, and heart-failure physicians, as well as ED and ICU physicians and nurses, is critical for managing treatment for these patients and for successful outcomes. This review is designed for critical care providers who may be the first to see these patients in the ED or ICU.

Development of a Double-Lumen Cannula for a Percutaneous RVAD

The objectives were to design/fabricate a double-lumen cannula (DLC) for a percutaneous right ventricular assist device (pRVAD) and to test the feasibility/performance of this pRVAD system. A 27 Fr DLC prototype was made and tested in six adult sheep. The pRVAD DLC was inserted into the right jugular vein; advanced through the superior vena cava, the right atrium (RA), the right ventricle (RV); ending in the pulmonary artery (PA). A CentriMag pump and optional gas exchanger were connected to the DLC. Blood was withdrawn from RA, pumped through gas exchanger, and perfused PA. Maximal pumping flow was maintained for 2 hours. The pRVAD DLC was successfully deployed in all six sheep. In first three sheep, maximal average pumping flow was less than 3 L/min because the DLC was advanced too far with drainage opening against RA side wall. In last three sheep with well-positioned DLC, average maximal flow was more than 3.5 L/min. The gas exchanger provided up to 230 ml/min CO2 removal and 174 ml/min O2 transfer. Our DLC-based pRVAD system is feasible for percutaneous right heart and respiratory assistance through a single cannulation. The pRVAD DLC can be easily placed prophylactically during left ventricular assist device implantation and removed as needed without additional open chest procedures.

Novel Therapeutic Strategies for Reducing Right Heart Failure Associated Mortality in Fibrotic Lung Diseases

Fibrotic lung diseases carry a significant mortality burden worldwide. A large proportion of these deaths are due to right heart failure and pulmonary hypertension. Underlying contributory factors which appear to play a role in the mechanism of progression of right heart dysfunction include chronic hypoxia, defective calcium handling, hyperaldosteronism, pulmonary vascular alterations, cyclic strain of pressure and volume changes, elevation of circulating TGF-β, and elevated systemic NO levels. Specific therapies targeting pulmonary hypertension include calcium channel blockers, endothelin (ET-1) receptor antagonists, prostacyclin analogs, phosphodiesterase type 5 (PDE5) inhibitors, and rho-kinase (ROCK) inhibitors. Newer antifibrotic and anti-inflammatory agents may exert beneficial effects on heart failure in idiopathic pulmonary fibrosis. Furthermore, right ventricle-targeted therapies, aimed at mitigating the effects of functional right ventricular failure, include β-adrenoceptor (β-AR) blockers, angiotensin-converting enzyme (ACE) inhibitors, antioxidants, modulators of metabolism, and 5-hydroxytryptamine-2B (5-HT2B) receptor antagonists. Newer nonpharmacologic modalities for right ventricular support are increasingly being implemented. Early, effective, and individualized therapy may prevent overt right heart failure in fibrotic lung disease leading to improved outcomes and quality of life.

Treatment for pulmonary arterial hypertension-associated right ventricular dysfunction

Pulmonary arterial hypertension (PAH) includes a heterogeneous group of diseases characterized by pulmonary vasoconstriction and remodeling of the lung circulation. Although PAH is a disease of the lungs, patients with PAH frequently die of right heart failure. Indeed, survival of patients with PAH depends on the adaptive response of the right ventricle (RV) to the changes in the lung circulation. PAH-specific drugs affect the function of the RV through afterload reduction and perhaps also through direct effects on the myocardium. Prostacyclins, type 5 phosphodiesterase inhibitors, and guanylyl cyclase stimulators may directly enhance myocardial contractility through increased cyclic adenosine and guanosine monophosphate availability. Although this may initially improve cardiac performance, the long-term effects on myocardial oxygen consumption and function are unclear. Cardiac effects of endothelin receptor antagonists may be opposite, as endothelin-1 is known to suppress cardiac contractility. Because PAH is increasingly considered as a disease with quasimalignant growth of cells in the pulmonary vascular wall, therapies are being developed that inhibit hypertrophy and angiogenesis, and promote apoptosis. The inherent danger of these therapies is a further compromise to the already ischemic, fibrotic, and dysfunctional RV. More recently, the right heart has been identified as a direct treatment target in PAH. The effects of well established therapies for left heart failure, such as β-adrenergic receptor blockers, inhibitors of the renin-angiotensin system, exercise training, and assist devices, are currently being investigated in PAH. Future treatment of patients with PAH will likely consist of a multifaceted approaches aiming to reduce the pressure in the lung circulation and improving right heart adaptation simultaneously.

Pulmonary Hypertension in the Intensive Care Unit

Pulmonary hypertension occurs as the result of disease processes increasing pressure within the pulmonary circulation, eventually leading to right ventricular failure. Patients may become critically ill from complications of pulmonary hypertension and right ventricular failure or may develop pulmonary hypertension as the result of critical illness. Diagnostic testing should evaluate for common causes such as left heart failure, hypoxemic lung disease and pulmonary embolism. Relatively few patients with pulmonary hypertension encountered in clinical practice require specific pharmacologic treatment of pulmonary hypertension targeting the pulmonary vasculature. Management of right ventricular failure involves optimization of preload, maintenance of systemic blood pressure and augmentation of inotropy to restore systemic perfusion. Selected patients may require pharmacologic therapy to reduce right ventricular afterload by directly targeting the pulmonary vasculature, but only after excluding elevated left heart filling pressures and confirming increased pulmonary vascular resistance. Critically-ill patients with pulmonary hypertension remain at high risk of adverse outcomes, requiring a diligent and thoughtful approach to diagnosis and treatment.

Devices in heart failure--the new revolution

Heart failure is a growing epidemic, with more patients living longer and suffering from this disease. There is a growing segment of patients who have persistent symptoms despite pharmacologic therapy. In an era when transplants are rare, the need for devices and interventions that can assist ventricular function is paramount. This review goes through the devices used in heart failure, including left ventricular reconstruction, aortic counterpulsation, short-term mechanical circulatory support, long-term mechanical circulatory support, and right heart interventions.

Short-term mechanical circulatory support for recovery from acute right ventricular failure: clinical outcomes

BACKGROUND

Acute right ventricular failure (ARVF) refractory to optimal medical management may require rescue therapy with mechanical circulatory support (MCS). The RV exhibits a greater capacity for rapid recovery than the left ventricle, making devices designed specifically for temporary RV MCS attractive. We report our experience with the Impella Right Direct (RD) and Right Peripheral (RP) temporary ventricular assist devices (Abiomed, Danvers, MA) in patients with ARVF.

METHODS

We conducted a retrospective cohort study examining the clinical outcomes of consecutive patients supported with the Impella RD or RP at 2 institutions during a 6-year period.

RESULTS

During the study period, 18 patients (67% men; mean age 57 ± 10 years) received MCS, 15 with the Impella RD and 3 with the Impella RP. Before RV MCS, all patients required intravenous inotropes, 7 (39%) required inhaled nitric oxide, 7 (39%) required intra-aortic balloon counterpulsation, and 2 (11%) had experienced a cardiac arrest. Device implantation resulted in an improvement in cardiac index (2.1 ± 0.1 liters/min/m(2) pre-implant vs 2.6 ± 0.2 liters/min/m(2) post-implant, p = 0.04) and reduced central venous pressure (22 ± 5 vs 15 ± 4 mm Hg, p < 0.01). Fourteen (78%) patients recovered sufficient RV function to facilitate device explanation after 7 days (range, 2-19 days) of support, and 4 (22%) patients died on support after 6 days (range 1-11 days). Survival to 30 days was 72% and to 1 year was 50%. At 1-year follow-up, the mean New York Heart Association functional classification was 1.3 ± 0.5, and only 1 patient demonstrated severe RV dysfunction on echocardiography.

CONCLUSIONS

Most patients with ARVF rapidly recover sufficient RV function to facilitate device explantation, highlighting an expanding role for minimally invasive temporary RV assist devices optimized for the treatment of recoverable ARVF.

Clinical manifestations and management of left ventricular assist device-associated infections

BACKGROUND

Infection is a serious complication of left ventricular assist device (LVAD) therapy. Published data regarding LVAD-associated infections (LVADIs) are limited by single-center experiences and use of nonstandardized definitions.

METHODS

We retrospectively reviewed 247 patients who underwent continuous-flow LVAD implantation from January 2005 to December 2011 at Mayo Clinic campuses in Minnesota, Arizona, and Florida. LVADIs were defined using the International Society for Heart and Lung Transplantation criteria.

RESULTS

We identified 101 episodes of LVADI in 78 patients (32%) from this cohort. Mean age (± standard deviation [SD]) was 57±15 years. The majority (94%) underwent Heartmate II implantation, with 62% LVADs placed as destination therapy. The most common type of LVADIs were driveline infections (47%), followed by bloodstream infections (24% VAD related, and 22% non-VAD related). The most common causative pathogens included gram-positive cocci (45%), predominantly staphylococci, and nosocomial gram-negative bacilli (27%). Almost half (42%) of the patients were managed by chronic suppressive antimicrobial therapy. While 14% of the patients had intraoperative debridement, only 3 underwent complete LVAD removal. The average duration (±SD) of LVAD support was 1.5±1.0 years. At year 2 of follow-up, the cumulative incidence of all-cause mortality was estimated to be 43%.

CONCLUSION

Clinical manifestations of LVADI vary on the basis of the type of infection and the causative pathogen. Mortality remained high despite combined medical and surgical intervention and chronic suppressive antimicrobial therapy. Based on clinical experiences, a management algorithm for LVADI is proposed to assist in the decision-making process.