A case series analysis of bicarbonate-based purge solution administration via Impella ventricular assist device.

PURPOSE: The Impella device historically required a heparin-based purge solution to reduce the risk of biomaterial deposition to maintain pump function. In April 2022, the Food and Drug Administration approved utilization of bicarbonate-based purge solutions (BBPS) as an alternative to heparin for patients who are intolerant to heparin or in whom heparin is contraindicated. The purpose of this case series is to report patient outcomes of Impella support with BBPS use at our institution. SUMMARY: Eighteen patients who received BBPS via the Impella CP or Impella 5.5 device were included in our review. Patients were included if they had BBPS administration for greater than 24 hours. All patients were followed for 72 hours after cessation of BBPS. Indications for BBPS were coagulopathy (n = 5, 28%), suspected HIT (n = 2, 11%), confirmed HIT (n = 1, 6%), and major bleeding (n = 10, 56%). Three patients (17%) experienced an Impella complication while on BBPS. One patient required pump exchange, one required removal of the Impella device, and one received alteplase for suspected purge block. Of these, two patients experienced complications greater than 21 days into BBPS therapy. CONCLUSION: This case series adds to the literature describing clinical outcomes for patients on Impella support with BBPS. While BBPS offers a viable option for the management of patients on Impella devices who are unable to tolerate heparin-based purge solutions, further data is needed to determine the longevity of the Impella device with BBPS to minimize risk of Impella complications.

Outcomes of Patients Transferred to Tertiary Care Centers for Treatment of Cardiogenic Shock: A Cardiogenic Shock Working Group Analysis.

BACKGROUND: Consensus recommendations for cardiogenic shock (CS) advise transfer of patients in need of advanced options beyond the capability of "spoke" centers to tertiary/"hub" centers with higher capabilities. However, outcomes associated with such transfers are largely unknown beyond those reported in individual health networks. OBJECTIVES: To analyze a contemporary, multicenter CS cohort with the aim of comparing characteristics and outcomes of patients between transfer (between spoke and hub centers) and nontransfer cohorts (those primarily admitted to a hub center) for both acute myocardial infarction (AMI-CS) and heart failure-related HF-CS. We also aim to identify clinical characteristics of the transfer cohort that are associated with in-hospital mortality. METHODS: The Cardiogenic Shock Working Group (CSWG) registry is a national, multicenter, prospective registry including high-volume (mostly hub) CS centers. Fifteen U.S. sites contributed data for this analysis from 2016-2020. RESULTS: Of 1890 consecutive CS patients enrolled into the CSWG registry, 1028 (54.4%) patients were transferred. Of these patients, 528 (58.1%) had heart failure-related CS (HF-CS), and 381 (41.9%) had CS related to acute myocardial infarction (AMI-CS). Upon arrival to the CSWG site, transfer patients were more likely to be in SCAI stages C and D, when compared to nontransfer patients. Transfer patients had higher mortality rates (37% vs 29%, < 0.001) than nontransfer patients; the differences were driven primarily by the HF-CS cohort. Logistic regression identified increasing age, mechanical ventilation, renal replacement therapy, and higher number of vasoactive drugs prior to or within 24 hours after CSWG site transfer as independent predictors of mortality among HF-CS patients. Conversely, pulmonary artery catheter use prior to transfer or within 24 hours of arrival was associated with decreased mortality rates. Among transfer AMI-CS patients, BMI > 28 kg/m2, worsening renal failure, lactate > 3 mg/dL, and increasing numbers of vasoactive drugs were associated with increased mortality rates. CONCLUSION: More than half of patients with CS managed at high-volume CS centers were transferred from another hospital. Although transfer patients had higher mortality rates than those who were admitted primarily to hub centers, the outcomes and their predictors varied significantly when classified by HF-CS vs AMI-CS.

Impact of Female Sex on Cardiogenic Shock Outcomes: A Cardiogenic Shock Working Group Report.

BACKGROUND: Studies reporting cardiogenic shock (CS) outcomes in women are scarce. OBJECTIVES: The authors compared survival at discharge among women vs men with CS complicating acute myocardial infarction (AMI-CS) and heart failure (HF-CS). METHODS: The authors analyzed 5,083 CS patients in the Cardiogenic Shock Working Group. Propensity score matching (PSM) was performed with the use of baseline characteristics. Logistic regression was performed for log odds of survival. RESULTS: Among 5,083 patients, 1,522 were women (30%), whose mean age was 61.8 ± 15.8 years. There were 30% women and 29.1% men with AMI-CS (P = 0.03). More women presented with de novo HF-CS compared with men (26.2% vs 19.3%; P < 0.001). Before PSM, differences in baseline characteristics and sex-specific outcomes were seen in the HF-CS cohort, with worse survival at discharge (69.9% vs 74.4%; P = 0.009) and a higher rate of maximum Society for Cardiac Angiography and Interventions stage E (26% vs 21%; P = 0.04) in women than in men. Women were less likely to receive pulmonary artery catheterization (52.9% vs 54.6%; P < 0.001), heart transplantation (6.5% vs 10.3%; P < 0.001), or left ventricular assist device implantation (7.8% vs 10%; P = 0.01). Regardless of CS etiology, women had more vascular complications (8.8% vs 5.7%; P < 0.001), bleeding (7.1% vs 5.2%; P = 0.01), and limb ischemia (6.8% vs 4.5%; P = 0.001). More vascular complications persisted in women after PSM (10.4% women vs 7.4% men; P = 0.06). CONCLUSIONS: Women with HF-CS had worse outcomes and more vascular complications than men with HF-CS. More studies are needed to identify barriers to advanced therapies, decrease complications, and improve outcomes of women with CS.

Clinical Course of Patients in Cardiogenic Shock Stratified by Phenotype.

BACKGROUND: Cardiogenic shock (CS) patients remain at 30% to 60% in-hospital mortality despite therapeutic innovations. Heterogeneity of CS has complicated clinical trial design. Recently, 3 distinct CS phenotypes were identified in the CSWG (Cardiogenic Shock Working Group) registry version 1 (V1) and external cohorts: I, "noncongested;" II, "cardiorenal;" and III, "cardiometabolic" shock. OBJECTIVES: The aim was to confirm the external reproducibility of machine learning-based CS phenotypes and to define their clinical course. METHODS: The authors included 1,890 all-cause CS patients from the CSWG registry version 2. CS phenotypes were identified using the nearest centroids of the initially reported clusters. RESULTS: Phenotypes were retrospectively identified in 796 patients in version 2. In-hospital mortality rates in phenotypes I, II, III were 23%, 41%, 52%, respectively, comparable to the initially reported 21%, 45%, and 55% in V1. Phenotype-related demographic, hemodynamic, and metabolic features resembled those in V1. In addition, 58.8%, 45.7%, and 51.9% of patients in phenotypes I, II, and III received mechanical circulatory support, respectively (P = 0.013). Receiving mechanical circulatory support was associated with increased mortality in cardiorenal (OR: 1.82 [95% CI: 1.16-2.84]; P = 0.008) but not in noncongested or cardiometabolic CS (OR: 1.26 [95% CI: 0.64-2.47]; P = 0.51 and OR: 1.39 [95% CI: 0.86-2.25]; P = 0.18, respectively). Admission phenotypes II and III and admission Society for Cardiovascular Angiography and Interventions stage E were independently associated with increased mortality in multivariable logistic regression compared to noncongested "stage C" CS (P < 0.001). CONCLUSIONS: The findings support the universal applicability of these phenotypes using supervised machine learning. CS phenotypes may inform the design of future clinical trials and enable management algorithms tailored to a specific CS phenotype.

Outflow cannula alignment in continuous flow left ventricular devices is associated with stroke.

We sought to evaluate whether differences in left ventricular assist device (LVAD) canula alignment are associated with stroke. There is a paucity of clinical data on contribution of LVAD canulae alignment to strokes. We conducted a retrospective analysis of patients who underwent LVAD implantation at Houston Methodist hospital from 2011 to 2016 and included those who had undergone cardiac computed tomography (CT) with contrast. LVAD graft alignment using X-ray, echocardiography, and cardiac CT was evaluated. The primary outcome was stroke within 1 year of LVAD implantation. Of the 101 patients that underwent LVAD Implantation and cardiac CT scan during the study period, 78 met inclusion criteria. The primary outcome occurred in 12 (15.4%) patients with a median time to stroke of 77 days (interquartile range: 42-132 days). Of these, 10 patients had an ischemic and two had hemorrhagic strokes. The predominant device type was Heart Mate II (94.8%). Patients with LVAD outflow cannula to aortic angle lesser than 37.5° and those with outflow graft diameter of anastomosis less than 1.5 cm (assessed by cardiac CT) had significantly higher stroke risk (p < 0.001 and p = 0.01 respectively). In HMII patients, a lower LVAD speed at the time of CT scan was associated with stroke. Further studies are needed to identify optimal outflow graft configuration to mitigate stroke risk.

Tissue plasminogen activator in left ventricular assist device-related intravascular hemolysis after failed augmented anticoagulation.

OBJECTIVES: We sought to examine the efficacy and safety of adding fibrinogen-guided low-dose multi-day Alteplase™ tissue plasminogen activator (tPA) in the management of intravascular hemolysis (IVH) in patients with the HeartMate II (HM-II) continuous flow (CF) left ventricular assist device (LVAD) who failed to achieve IVH resolution with conventional augmented anticoagulation (AAC). BACKGROUND: IVH in patients with LVAD is often treated with AAC, failing which pump exchange is considered. We hypothesized that a trial of low-dose tPA after failed AAC therapy could resolve IVH and prevent pump exchange in some patients. METHODS: We performed a retrospective study of 31 HM-II CF LVAD patients admitted to our center from January 2015 to January 2020 for IVH management who received tPA following failed AAC. Primary 6-month outcomes included successful IVH resolution, unsuccessful IVH resolution requiring pump exchange, gastrointestinal bleeding, ischemic and hemorrhagic cerebrovascular accident (CVA), and death. RESULTS: Thirty-one patients with IVH were treated with tPA following failed AAC. Successful resolution of IVH occurred in 22/31 (71%) patients. Pump exchange occurred in 9/31 (29%) patients. Gastrointestinal bleeding occurred in 7/31 (22.6%) patients. Ischemic CVA occurred in 6/31 (19.4%) patients. CONCLUSIONS: Management of IVH with administration of low-dose tPA after failed AAC is feasible and may prevent pump exchange in some patients.

Criteria for Defining Stages of Cardiogenic Shock Severity.

BACKGROUND: Risk-stratifying patients with cardiogenic shock (CS) is a major unmet need. The recently proposed Society for Cardiovascular Angiography and Interventions (SCAI) staging system for CS severity lacks uniform criteria defining each stage. OBJECTIVES: The purpose of this study was to test parameters that define SCAI stages and explore their utility as predictors of in-hospital mortality in CS. METHODS: The CS Working Group registry includes patients from 17 hospitals enrolled between 2016 and 2021 and was used to define clinical profiles for CS. We selected parameters of hypotension and hypoperfusion and treatment intensity, confirmed their association with mortality, then defined formal criteria for each stage and tested the association between both baseline and maximum Stage and mortality. RESULTS: Of 3,455 patients, CS was caused by heart failure (52%) or myocardial infarction (32%). Mortality was 35% for the total cohort and higher among patients with myocardial infarction, out-of-hospital cardiac arrest, and treatment with increasing numbers of drugs and devices. Systolic blood pressure, lactate level, alanine transaminase level, and systemic pH were significantly associated with mortality and used to define each stage. Using these criteria, baseline and maximum stages were significantly associated with mortality (n = 1,890). Lower baseline stage was associated with a higher incidence of stage escalation and a shorter duration of time to reach maximum stage. CONCLUSIONS: We report a novel approach to define SCAI stages and identify a significant association between baseline and maximum stage and mortality. This approach may improve clinical application of the staging system and provides new insight into the trajectory of hospitalized CS patients. (Cardiogenic Shock Working Group Registry [CSWG]; NCT04682483).

Degree of change in right ventricular adaptation measures during axillary Impella support informs risk stratification for early, severe right heart failure following durable LVAD implantation.

Risk assessment for early, severe right heart failure (RHF) after LVAD implantation remains imperfect. We sought to define the differences in RV adaptation and load after axillary Impella support between patients who experienced RHF and those who did not. Seventeen of 18 patients included were deemed intermediate or high risk for RHF by EUROMACS-RHF score. Before Impella insertion, RV adaptation parameters (RAP, RAP:PCWP, PAPi) were worse in the non-RHF group compared to the RHF group. In both groups, RV load parameters (effective pulmonary arterial elastance, pulmonary vascular resistance, and pulmonary vascular compliance) improved after Impella insertion. Lesser improvements in RV adaptation were seen in the RHF group. Moreover, load-to-adaptation relationships (EA/RAP and EA/RAP:PCWP) worsened to a greater degree. In patients at intermediate or high risk for RHF after LVAD, assessment of RV adaptation and load during axillary Impella support may improve risk stratification.

RNA sequencing of blood in coronary artery disease: involvement of regulatory T cell imbalance.

BACKGROUND: Cardiovascular disease had a global prevalence of 523 million cases and 18.6 million deaths in 2019. The current standard for diagnosing coronary artery disease (CAD) is coronary angiography. Surprisingly, despite well-established clinical indications, up to 40% of the one million invasive cardiac catheterizations return a result of 'no blockage'. The present studies employed RNA sequencing of whole blood to identify an RNA signature in patients with angiographically confirmed CAD. METHODS: Whole blood RNA was depleted of ribosomal RNA (rRNA) and analyzed by single-molecule sequencing of RNA (RNAseq) to identify transcripts associated with CAD (TRACs) in a discovery group of 96 patients presenting for elective coronary catheterization. The resulting transcript counts were compared between groups to identify differentially expressed genes (DEGs). RESULTS: Surprisingly, 98% of DEGs/TRACs were down-regulated ~ 1.7-fold in patients with mild to severe CAD (> 20% stenosis). The TRACs were independent of comorbid risk factors for CAD, such as sex, hypertension, and smoking. Bioinformatic analysis identified an enrichment in transcripts such as FoxP1, ICOSLG, IKZF4/Eos, SMYD3, TRIM28, and TCF3/E2A that are likely markers of regulatory T cells (Treg), consistent with known reductions in Tregs in CAD. A validation cohort of 80 patients confirmed the overall pattern (92% down-regulation) and supported many of the Treg-related changes. TRACs were enriched for transcripts associated with stress granules, which sequester RNAs, and ciliary and synaptic transcripts, possibly consistent with changes in the immune synapse of developing T cells. CONCLUSIONS: These studies identify a novel mRNA signature of a Treg-like defect in CAD patients and provides a blueprint for a diagnostic test for CAD. The pattern of changes is consistent with stress-related changes in the maturation of T and Treg cells, possibly due to changes in the immune synapse.

Remote versus early corticosteroid wean outcomes in heart transplant recipients in the contemporary era.

PURPOSE: The risks and benefits of remote corticosteroid weaning in heart transplant recipients more than 2 years post-transplant are unknown. We compared outcomes in patients undergoing early and remote steroid weaning after heart transplantation. METHODS: We performed a retrospective study (range 09, 1991-04, 2017). Primary outcomes included short-term and long-term mortality, allograft dysfunction, and burden of rejection. Secondary outcomes included impact on hemoglobin A1c, lipid panel, bone scan T-score, and body mass index. RESULTS: 63 patients underwent corticosteroid weaning between 2012 and 2017. Outcomes of patients weaned early (n = 34; median time from transplant = 1.1 years) were compared with those weaned late (n = 29; median time from transplant = 4.4 years). 52 (82.5%) patients were successfully weaned off corticosteroids. No statistically significant difference in outcomes was found between the early and late weaning groups (p = .20). There were no differences in allograft function (p-value = .16), incidence of rejection (p = .46), or mortality (p = .15). Improvement in metabolic profile was seen in both groups but was not statistically significant. CONCLUSIONS: In heart transplant recipients, remote vs early weaning of corticosteroids is not associated with significant differences in graft function or the incidence of rejection after 1-year follow-up. Moreover, there were no significant differences in survival up to 3 years between the two groups.

Management of Cardiogenic Shock in a Cardiac Intensive Care Unit.

Cardiogenic shock (CS) is a complex condition characterized by end-organ hypoperfusion and requiring pharmacologic and/or mechanical circulatory support. It is caused by a decline in cardiac output due to a primary cardiac disorder. CS is frequently complicated by multiorgan system dysfunction that requires a multidisciplinary approach in a critical care setting. Appropriate use of diagnostic data using tools available in a modern cardiac intensive care unit should guide optimal management incorporating both pharmacologic and nonpharmacologic therapies to minimize morbidity and mortality.

Use of Tissue Plasminogen Activator Alteplase for Suspected Impella Thrombosis.

BACKGROUND: Impella devices are being increasingly used to manage cardiogenic shock. The incidence of thrombosis and hemolysis in patients on Impella support increases with longer durations of use, and the management of Impella thrombosis remains ill-defined. METHODS: In this case series, we describe our institutional use of tissue plasminogen activator (tPA) alteplase in the Impella purge solution (0.04 or 0.08 mg/ml tPA in sterile water) for management of suspected Impella thrombosis in five patients, each with a different clinical course, treatment, and outcome. Given the limited evidence on the diagnosis of Impella thrombosis, suspicion was driven by the presence of decreased purge flow rates, increased purge pressures, and markers of hemolysis such as elevated lactate dehydrogenase and hematuria. OUTCOMES: In all cases, tPA administration resulted in resolution of low purge flow rates and high purge pressures. No major bleeding complications were directly associated with tPA. Two patients were bridged successfully to heart transplantation, two patients underwent left ventricular assist device implantation, and one patient died after withdrawal of care. CONCLUSION: Based on our experience, tPA administration appears to be a viable and safe salvage option to delay or prevent device exchange in the setting of suspected Impella thrombosis.

The Evolution of Mechanical Circulatory Support.

The field of mechanical circulatory support (MCS) has evolved from earlier-generation pulsatile-flow devices that were primarily used to support critically ill patients in the hospital to newer-generation continuous-flow devices that permit hospital discharge and resumption of normal life activities. The technology is used to bridge transplant-eligible patients and can be used for long-term support of patients who are transplant ineligible. Left ventricular assist devices are proved to improve long-term survival and quality of life for patients with advanced heart failure. Adverse events associated with MCS therapy remain the Achilles heel of the field and strategies to improve biocompatibility are ongoing.

Continuous-Flow Left Ventricular Assist Device-Related Gastrointestinal Bleeding.

Continuous-flow (CF) left ventricular assist devices (LVADs) are a safe and durable therapeutic option for patients with advanced heart failure as a bridge to transplant or as destination therapy. Despite the remarkable technological advances in device design and increasing familiarity with the physiologic effects of CF, major complications such as gastrointestinal bleeding (GIB) continue to cause significant morbidity. The causes underlying CF-LVAD-related GIB are multifactorial. Accordingly, management strategies for CF-LVAD-related GIB encompass a wide range of therapeutic modalities. This article reviews the epidemiology, pathophysiology, risk factors, and treatment options for the management of this complex complication.

Ventricular Assist Device Therapy in Older Patients With Heart Failure: Characteristics and Outcomes.

BACKGROUND: Limited data exist on outcomes in patients ≥70 years of age supported with the use of continuous-flow left ventricular assist devices (LVADs). METHODS: Data on 1149 continuous-flow LVAD recipients was queried from the Mechanical Circulatory Support Research Network. Groups were assigned based on age: ≥70 years ("older patients") and <70 years. The primary outcome was survival at one-year based on age grouping. RESULTS: Compared with younger patients (54.3 ± 11.2 y; n = 986), older patients (73.4 ± 3.0 y) constituted only 14% of LVAD implants. Older patients had similar rates of device thrombosis (P = .47) and stroke (P = .44), but survival-free of gastrointestinal bleeding (GIB) at 1 year was lower compared with younger patients (58% vs 69%; P < .01). Unadjusted survival at 1 year in older patients was 75% compared with 84% in younger patients, and at 2 years 65% versus 73% (P = .18). Age ≥70 years was not associated with increased mortality (adjusted hazard ratio [aHR] 0.94, 95% confidence interval [CI] 0.70-1.26; P = .67). Preoperative creatinine (aHR 1.57, 95% CI: 1.30-1.89, P < .0001), bilirubin (aHR 1.22, 95% CI 1.05-1.42; P = .010), and ischemic cardiomyopathy (aHR 1.43, 95% CI 1.11-1.84; P = .005) portended increased risk of death. In older patients, the only predictor of mortality was creatinine (HR 2.1, 95% CI 1.2-3.4; P = .007). Creatinine ≥1.4 mg/dL was associated with a 1-year survival of 65%, compared with 84% when the creatinine was <1.4 mg/dL (P = .009). CONCLUSION: Age >70 years is an important consideration when assessing LVAD risk, but other correlates may be more predictive of LVAD survival. Older patients without renal dysfunction have survival similar to younger patients. Older patients should be counseled about age-correlated risks, including higher rates of GIB.

Coagulation Abnormalities in Heart Failure: Pathophysiology and Therapeutic Implications.

Heart failure (HF) represents a heterogeneous condition characterized by vulnerabilities in the blood, vasculature, and impaired flow dynamics that predispose to both arterial and venous thrombosis. Despite evidence-based advances in the medical and device management of chronic HF, it remains a leading cause of morbidity and mortality in the USA due to repeat hospitalizations and comorbid conditions such as atrial fibrillation (AF) and stroke. The presence of platelet activation and hypercoagulability in HF has been well documented. Anticoagulation is effective in HF when comorbidities such as AF and prior venous thromboembolism exist. However, data is less clear for HF in sinus rhythm. Moreover, there is a paucity of data regarding antiplatelet therapy in HF. No consensus guidelines exist regarding the precise role of antiplatelet or antithrombotic therapy in HF. This review addresses the pathophysiology of coagulation abnormalities in HF, examines the available evidence regarding the use of anticoagulants and antiplatelet agents in HF, and discusses its therapeutic implications.

A novel approach for identifying causal models of complex diseases from family data.

Causal models including genetic factors are important for understanding the presentation mechanisms of complex diseases. Familial aggregation and segregation analyses based on polygenic threshold models have been the primary approach to fitting genetic models to the family data of complex diseases. In the current study, an advanced approach to obtaining appropriate causal models for complex diseases based on the sufficient component cause (SCC) model involving combinations of traditional genetics principles was proposed. The probabilities for the entire population, i.e., normal-normal, normal-disease, and disease-disease, were considered for each model for the appropriate handling of common complex diseases. The causal model in the current study included the genetic effects from single genes involving epistasis, complementary gene interactions, gene-environment interactions, and environmental effects. Bayesian inference using a Markov chain Monte Carlo algorithm (MCMC) was used to assess of the proportions of each component for a given population lifetime incidence. This approach is flexible, allowing both common and rare variants within a gene and across multiple genes. An application to schizophrenia data confirmed the complexity of the causal factors. An analysis of diabetes data demonstrated that environmental factors and gene-environment interactions are the main causal factors for type II diabetes. The proposed method is effective and useful for identifying causal models, which can accelerate the development of efficient strategies for identifying causal factors of complex diseases.

Structure-based virtual screening approach to the discovery of novel inhibitors of eyes absent 2 phosphatase with various metal chelating moieties.

Despite a series of persuasive experimental evidence for the involvement of eyes absent protein tyrosine phosphatases in various human cancers, no small-molecule inhibitor has been reported so far. We have identified seven novel inhibitors of eyes absent homologue 2 (Eya2) with IC(50) values ranging from 1 to 70 µm by the virtual screening with docking simulations and enzyme inhibition assay. Atomic charges of the active-site Mg(2+) ion complex are calculated to enhance the accuracy of docking simulations. The newly discovered inhibitors are structurally diverse and have various chelating groups for the Mg(2+) ion. The interactions with the amino acid residues responsible for the stabilizations of the inhibitors in the active site of Eya2 are addressed in detail.

Combined delivery of heme oxygenase-1 gene and fibroblast growth factor-2 protein for therapeutic angiogenesis.

Ectopic expression of heme oxygenase-1 (HO-1) in ischemic tissue protects the tissue from apoptosis and necrosis and promotes angiogenesis. However, apoptosis and necrosis will decrease HO-1 gene transfection efficacy. We hypothesized that fibroblast growth factor-2 (FGF2) would attenuate ischemic damage during the incipient period, improve HO-1 gene transfection and, in turn, enhance neovascularization. To test this hypothesis, we employed a mouse model of hindlimb ischemia and treated the mice with HO-1 gene therapy alone, FGF2 alone, or HO-1 gene therapy plus FGF2. As controls, a group of mice was left untreated. At 12h, prior to the expression of exogenously delivered HO-1, apoptosis was significantly reduced in mice treated with FGF2, either alone or in combination with HO-1 gene therapy. At 3 days, HO-1 expression was greater in mice that also received FGF2 than in mice treated with HO-1 gene therapy alone. The expression of angiogenic growth factors and angiogenesis was greater in mice treated with HO-1 gene therapy plus FGF2 than in mice treated with HO-1 gene therapy alone. These data indicate that FGF2 rescued muscle necrosis prior to the exogenous expression of HO-1 and enhanced HO-1 gene transfection in ischemic murine limbs.