JaBaris D. Swain

Cardiac Surgery in Jehovah's Witness Patients: Ten-Year Experience

BACKGROUNDnCardiac surgery in Jehovahs Witnesses poses unique challenges. We have developed a comprehensive multimodality program for these patients and have obtained excellent results.nnnMETHODSnNinety-one Jehovahs Witness patients underwent cardiac surgery between 2000 and 2010. Preoperative, intraoperative, and postoperative considerations in the conduct of bloodless surgery in the Jehovahs Witness population are discussed. Mortality for isolated coronary artery bypass graft surgery and isolated aortic valve replacement was compared with predicted mortality from The Society of Thoracic Surgeons (STS) risk models. Perioperative outcomes were stratified by urgent and elective status of operations.nnnRESULTSnMean age was 65±12.4 years. Comorbid conditions included hypertension (84.6%), diabetes mellitus (48.4%), previous myocardial infarction (23.1%), chronic lung disease (38.5%), peripheral vascular disease (20.9%), and renal failure (11%). In-hospital mortality was 5.5% (n=5). Mortality for isolated coronary artery bypass graft surgery and isolated aortic valve replacement was 2.2% (observed to expected ratio=1.05, 95% confidence interval: 0 to 3.02) and 5.6% (observed to expected=1.46, 95% confidence interval: 0 to 3.76), respectively. Other complications included reoperation (all=8.8%, cardiac=2.2%), sepsis (2.2%), sternal wound infection (1.1%), transient ischemic attack (1.1%), renal failure requiring dialysis (1.1%), and prolonged ventilation (18.7%). Major complication rates were not significantly different between the elective group and the urgent group.nnnCONCLUSIONSnBloodless cardiac surgery in Jehovahs Witness patients can be performed with excellent outcomes in both elective and urgent situations. Mortality rates for isolated coronary artery bypass graft surgery and isolated aortic valve replacement are within the expected 95% confidence intervals of STS predicted mortality.

Cardiac gene therapy: optimization of gene delivery techniques in vivo.

Vector-mediated cardiac gene therapy holds tremendous promise as a translatable platform technology for treating many cardiovascular diseases. The ideal technique is one that is efficient and practical, allowing for global cardiac gene expression, while minimizing collateral expression in other organs. Here we survey the available in vivo vector-mediated cardiac gene delivery methods--including transcutaneous, intravascular, intramuscular, and cardiopulmonary bypass techniques--with consideration of the relative merits and deficiencies of each. Review of available techniques suggests that an optimal method for vector-mediated gene delivery to the large animal myocardium would ideally employ retrograde and/or anterograde transcoronary gene delivery,extended vector residence time in the coronary circulation, an increased myocardial transcapillary gradient using physical methods, increased endothelial permeability with pharmacological agents, minimal collateral gene expression by isolation of the cardiac circulation from the systemic, and have low immunogenicity.

Current strategies for myocardial gene delivery

Existing methods of cardiac gene delivery can be classified by the site of injection, interventional approach and type of cardiac circulation at the time of transfer. General criteria to assess the efficacy of a given delivery method include: global versus regional myocardial transduction, technical complexity and the pathophysiological effects associated with its use, delivery-related collateral expression and the delivery-associated inflammatory and immune response. Direct gene delivery (intramyocardial, endocardial, epicardial) may be useful for therapeutic angiogenesis and for focal arrhythmia therapy but with gene expression which is primarily limited to regions in close proximity to the injection site. An often unappreciated limitation of these techniques is that they are frequently associated with substantial systemic vector delivery. Percutaneous infusion of vector into the coronary arteries is minimally invasive and allows for transgene delivery to the whole myocardium. Unfortunately, efficiency of intracoronary delivery is highly variable and the short residence time of vector within the coronary circulation and significant collateral organ expression limit its clinical potential. Surgical techniques, including the incorporation of cardiopulmonary bypass with isolated cardiac recirculation, represent novel delivery strategies that may potentially overcome these limitations; yet, these techniques are complex with inherent morbidity that must be thoroughly evaluated before safe translation into clinical practice. Characteristics of the optimal technique for gene delivery include low morbidity, increased myocardial transcapillary gradient, extended vector residence time in the coronary circulation and exclusion of residual vector from the systemic circulation after delivery to minimize extracardiac expression and to mitigate a cellular immune response. This article is part of a Special Section entitled Special Section: Cardiovascular Gene Therapy.

AAV6-βARKct gene delivery mediated by molecular cardiac surgery with recirculating delivery (MCARD) in sheep results in robust gene expression and increased adrenergic reserve

OBJECTIVEnGenetic modulation of heart function is a novel therapeutic strategy. We investigated the effect of molecular cardiac surgery with recirculating delivery (MCARD)-mediated carboxyl-terminus of the β-adrenergic receptor kinase (βARKct) gene transfer on cardiac mechanoenergetics and β-adrenoreceptor (βAR) signaling.nnnMETHODSnAfter baseline measurements, sheep underwent MCARD-mediated delivery of 10(14) genome copies of self-complimentary adeno-associated virus (scAAV6)-βARKct. Four and 8 weeks after MCARD, mechanoenergetic studies using magnetic resonance imaging were performed. Tissues were analyzed with real-time quantitative polymerase chain reaction (RT-qPCR) and Western blotting. βAR density, cyclic adenosine monophosphate levels, and physiologic parameters were evaluated.nnnRESULTSnThere was a significant increase in dP/dt(max) at 4 weeks: 1384 ± 76 versus 1772 ± 182 mm Hg/s; and the increase persisted at 8 weeks in response to isoproterenol (Pxa0<xa0.05). Similarly, the magnitude of dP/dt(min) increased at both 4 weeks and 8 weeks with isoproterenol stimulation (Pxa0<xa0.05). At 8 weeks, potential energy was conserved, whereas in controls there was a decrease in potential energy (Pxa0<xa0.05) in response to isoproterenol. RT-qPCR confirmed robustness of βARKct expression throughout the left ventricle and undetectable expression in extracardiac tissues. Quantitative Western blot data confirmed higher expression of βARKct in the left ventricle: 0.46 ± 0.05 versus 0.00 in lung and liver (Pxa0<xa0.05). Survival was 100% and laboratory parameters of major organ function were within normal limits.nnnCONCLUSIONSnMCARD-mediated βARKct delivery is safe, results in robust cardiac-specific gene expression, enhances cardiac contractility and lusitropy, increases adrenergic reserve, and improves energy utilization efficiency in a preclinical large animal model.

MCARD-Mediated Gene Transfer of GRK2 Inhibitor in Ovine Model of Acute Myocardial Infarction

Abstractβ-Adrenergic receptor (βAR) dysfunction in acute myocardial infarction (MI) is associated with elevated levels of the G-protein-coupled receptor kinase-2 (GRK2), which plays a key role in heart failure progression. Inhibition of GRK2 via expression of a peptide βARKct transferred by molecular cardiac surgery with recirculating delivery (MCARD) may be a promising intervention. Five sheep underwent scAAV6-mediated MCARD delivery of βARKct, and five received no treatment (control). After a 3-week period, the branch of the circumflex artery (OM1) was ligated. Quantitative PCR data showed intense βARKct expression in the left ventricle (LV). Circumferential fractional shortening was 23.4u2009±u20097.1xa0% (baseline) vs. −2.9u2009±u20095.2xa0% (pu2009<u20090.05) in the control at 10xa0weeks. In the MCARD-βARKct group, this parameter was close to baseline. The same trend was observed with LV wall thickening. Cardiac index fully recovered in the MCARD-βARKct group. LV end-diastolic volume and LV end-diastolic pressure did not differ in both groups. MCARD-mediated βARKct gene expression results in preservation of regional and global systolic function after acute MI without arresting progressive ventricular remodeling.

A translatable, closed recirculation system for AAV6 vector-mediated myocardial gene delivery in the large animal.

Current strategies for managing congestive heart failure are limited, validating the search for an alternative treatment modality. Gene therapy holds tremendous promise as both a practical and translatable technology platform. Its effectiveness is evidenced by the improvements in cardiac function observed in vector-mediated therapeutic transgene delivery to the murine myocardium. A large animal model validating these results is the likely segue into clinical application. However, controversy still exists regarding a suitable method of vector-mediated cardiac gene delivery that provides for efficient, global gene transfer to the large animal myocardium that is also clinically translatable and practical. Intramyocardial injection and catheter-based coronary delivery techniques are attractive alternatives with respect to their clinical applicability; yet, they are fraught with numerous challenges, including concerns regarding collateral gene expression in other organs, low efficiency of vector delivery to the myocardium, inhomogeneous expression, and untoward immune response secondary to gene delivery. Cardiopulmonary bypass (CPB) delivery with dual systemic and isolated cardiac circuitry precludes these drawbacks and has the added advantage of allowing for control of the pharmacological milieu, multiple pass recirculation through the coronary circulation, the selective addition of endothelial permeabilizing agents, and an increase in vector residence time. Collectively, these mechanics significantly improve the efficiency of global, vector-mediated cardiac gene delivery to the large animal myocardium, highlighting a potential therapeutic strategy to be extended to some heart failure patients.

The Perfect ECMO Candidate

One quiet Saturday morning, as I sat down in front of the computer and began to review my patient charts, an uncomfortably familiar alarm sounded overhead:“Attention please. Cardiothoracic surgery STAT to the medical intensive care unit.”nnThis announcement is used at my hospital, invariably