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.

Update on combined heart and liver transplantation: evolving patient selection, improving outcomes, and outstanding questions

PURPOSE OF REVIEW

Combined heart and liver transplantation (CHLT) is an uncommon but increasingly performed procedure with rising need as the population who has undergone Fontan palliation for single ventricle physiology grows. This article reviews the current literature to summarize what is known about patient selection and outcomes and highlights the questions that remain.

RECENT FINDINGS

Congenital heart disease (CHD) with Fontan-associated liver disease (FALD) has surpassed noncongenital heart disease as the most common indication for CHLT. In patients with failing Fontan physiology, accurate assessment of recoverability of liver injury remains challenging and requires multifaceted evaluation to determine who would benefit from isolated versus dual organ transplantation. Patient survival has improved over time without significant differences between those with and without a diagnosis of CHD. En bloc surgical technique and best use of intraoperative mechanical circulatory support are topics of interest as the field continues to evolve.

SUMMARY

A more refined understanding of appropriate patient selection and indication-specific outcomes will develop as we gain more experience with this complex operation and perform prospective, randomized studies.

Higher order genomic organization and epigenetic control maintain cellular identity and prevent breast cancer

Cells establish and sustain structural and functional integrity of the genome to support cellular identity and prevent malignant transformation. In this review, we present a strategic overview of epigenetic regulatory mechanisms including histone modifications and higher order chromatin organization (HCO) that are perturbed in breast cancer onset and progression. Implications for dysfunctions that occur in hormone regulation, cell cycle control, and mitotic bookmarking in breast cancer are considered, with an emphasis on epithelial-to-mesenchymal transition and cancer stem cell activities. The architectural organization of regulatory machinery is addressed within the contexts of translating cancer-compromised genomic organization to advances in breast cancer risk assessment, diagnosis, prognosis, and identification of novel therapeutic targets with high specificity and minimal off target effects.