Right-Sided Mechanical Circulatory Support - A Hemodynamic Perspective

Protected cardiac surgery: strategic mechanical circulatory support to improve postcardiotomy mortality

PURPOSE OF REVIEW

To examine the evolving landscape of cardiac surgery, focusing on the increasing complexity of patients and the role of mechanical circulatory support (MCS) in managing perioperative low cardiac output syndrome (P-LCOS).

RECENT FINDINGS

P-LCOS is a significant predictor of mortality in cardiac surgery patients. Preoperative risk factors, such as cardiogenic shock and elevated lactate levels, can help identify those at higher risk. Proactive use of MCS, rather than reactive implementation after P-LCOS develops, may lead to improved outcomes by preventing severe organ hypoperfusion. The emerging concept of "protected cardiac surgery" emphasizes early identification of these high-risk patients and planned MCS utilization. Additionally, specific MCS strategies are being developed and refined for various cardiac conditions, including AMI-CS, valvular surgeries, and pulmonary thromboendarterectomy.

SUMMARY

This paper explores the shifting demographics and complexities in cardiac surgery patients. It emphasizes the importance of proactive, multidisciplinary approaches to identify high-risk patients and implement early MCS to prevent P-LCOS and improve outcomes. The concept of protected cardiac surgery, involving planned MCS use and shared decision-making, is highlighted. The paper also discusses MCS strategies tailored to specific cardiac procedures and the ethical considerations surrounding MCS implementation.

The Management of Cardiogenic Shock From Diagnosis to Devices: A Narrative Review

Cardiogenic shock (CS) is a heterogenous syndrome broadly characterized by inadequate cardiac output leading to tissue hypoperfusion and multisystem organ dysfunction that carries an ongoing high mortality burden. The management of CS has advanced rapidly, especially with the incorporation of temporary mechanical circulatory support (tMCS) devices. A thorough understanding of how to approach a patient with CS and to select appropriate monitoring and treatment paradigms is essential in modern ICUs. Timely characterization of CS severity and hemodynamics is necessary to optimize outcomes, and this may be performed best by multidisciplinary shock-focused teams. In this article, we provide a review of CS aimed to inform both the cardiology-trained and non-cardiology-trained intensivist provider. We briefly describe the causes, pathophysiologic features, diagnosis, and severity staging of CS, focusing on gathering key information that is necessary for making management decisions. We go on to provide a more detailed review of CS management principles and practical applications, with a focus on tMCS. Medical management focuses on appropriate medication therapy to optimize perfusion-by enhancing contractility and minimizing afterload-and to facilitate decongestion. For more severe CS, or for patients with decompensating hemodynamic status despite medical therapy, initiation of the appropriate tMCS increasingly is common. We discuss the most common devices currently used for patients with CS-phenotyping patients as having left ventricular failure, right ventricular failure, or biventricular failure-and highlight key available data and particular points of consideration that inform tMCS device selection. Finally, we highlight core components of sedation and respiratory failure management for patients with CS.

Hemodynamical Evaluation of a New Surgically Implanted Pulsatile Right Ventricular Assist Device Driven by a Conventional Intra-Aortic Balloon Pump Console

Severe right heart failure, often overlooked and challenging to manage, has prompted a growing interest in innovative approaches to provide functional support. This study uses experimentation in large porcine models to introduce a novel prototype of a pulsatile mechanical circulatory support device and document its effects when deployed as a right ventricular assist device (RVAD). The pulsatile ventricular assist platform (pVAP), featuring a membrane pump driven by an intra-aortic balloon pump console, actively generates pulsatile flow to propel right ventricular blood into the pulmonary artery. This novel prototype demonstrates promising potential in addressing the challenges of right heart failure management. After preliminary in vitro assessments, the pVAP was tested on seven porcine models in a healthy state and after the induction of right ventricular failure. During the procedure, a set of standard (ie, standard-of-care) hemodynamic measurements was obtained. Additionally, invasive pressure-volume loop analysis was employed to examine left ventricular hemodynamics. Results indicated that activation of the pVAP during right ventricular failure significantly improved systemic hemodynamics and enhanced left ventricular function. This study sheds light on the potential of the pVAP in managing right heart failure.

Medical and Mechanical Circulatory Support of the Failing Right Ventricle

PURPOSE OF REVIEW

To describe medical therapies and mechanical circulatory support devices used in the treatment of acute right ventricular failure.

RECENT FINDINGS

Experts have proposed several algorithms providing a stepwise approach to medical optimization of acute right ventricular failure including tailored volume administration, ideal vasopressor selection to support coronary perfusion, inotropes to restore contractility, and pulmonary vasodilators to improve afterload. Studies have investigated various percutaneous and surgically implanted right ventricular assist devices in several clinical settings. The initial management of acute right ventricular failure is often guided by invasive hemodynamic data tracking parameters of circulatory function with the use of pharmacologic therapies. Percutaneous microaxial and centrifugal extracorporeal pumps bypass the failing RV and support circulatory function in severe cases of right ventricular failure.

Ambulatory 7-day mechanical circulatory support in sheep model of pulmonary hypertension and right heart failure

BACKGROUND

Right heart failure is the major cause of death in pulmonary hypertension. Lung transplantation is the only long-term treatment option for patients who fail medical therapy. Due to the scarcity of donor lungs, there is a critical need to develop durable mechanical support for the failing right heart. A major design goal for durable support is to reduce the size and complexity of devices to facilitate ambulation. Toward this end, we sought to deploy wearable mechanical support technology in a sheep disease model of chronic right heart failure.

METHODS

In 6 sheep with chronic right heart failure, a mechanical support system consisting of an extracorporeal blood pump coupled with a gas exchange unit was attached in a right atrium-to-left atrium configuration for up to 7 days. Circuit performance, hematologic parameters, and animal hemodynamics were analyzed.

RESULTS

Six subjects underwent the chronic disease model for 56 to 71 days. Three of the subjects survived to the 7-day end-point for circulatory support. The circuit provided 2.8 (0.5) liter/min of flow compared to the native pulmonary blood flow of 3.5 (1.1) liter/min. The animals maintained physiologically balanced blood gas profile with a sweep flow of 1.2 (1.0) liter/min. Two animals freely ambulated while wearing the circuit.

CONCLUSIONS

Our novel mechanical support system provided physiologic support for a large animal model of pulmonary hypertension with right heart failure. The small footprint of the circuit and the low sweep requirement demonstrate the feasibility of this technology to enable mobile ambulatory applications.

Sepsis Management in the Cardiac Intensive Care Unit

Septic shock management in the cardiac intensive care unit (CICU) is challenging due to the complex interaction of pathophysiology between vasodilatory and cardiogenic shock, complicating how to optimally deploy fluid resuscitation, vasopressors, and mechanical circulatory support devices. Because mixed shock portends high mortality and morbidity, familiarity with quality, contemporary clinical evidence surrounding available therapeutic tools is needed to address the resultant wide range of complications that can arise. This review integrates pathophysiology principles and clinical recommendations to provide an organized, topic-based review of the nuanced intricacies of managing sepsis in the CICU.

Device-based therapies for decompensated heart failure

PURPOSE OF REVIEW

Despite improvements in medical therapies, patients with heart failure continue to suffer significant morbidity and mortality. Acute decompensated heart failure (ADHF) remains a common and serious medical condition with a myriad of implications on patient survival and quality of life, and heart failure related readmissions persist [1-3].

RECENT FINDINGS

From the detection of prehospitalization decompensation and inpatient management of ADHF to stabilization of cardiogenic shock and durable mechanical circulatory support, device-based therapies are utilized across the spectrum of heart failure management. At present, there are numerous device-based therapies commonly used in clinical practice and many more devices in the early clinical-trial phase aimed at attenuation of ADHF.

SUMMARY

In this review, we examine recent updates in the breadth and use of devices-based therapies in these three main domains: ambulatory heart failure, acute decompensated heart failure, and cardiogenic shock. Device-based therapies for decompensated heart failure will continue to grow in number, indication, and complexity, making recognition and familiarity with available technologies of increased importance for research and clinical practice.