Atrial appendage angiotensin-converting enzyme-2, aging and cardiac surgical patients: a platform for understanding aging-related coronavirus disease-2019 vulnerabilities.

PURPOSE OF REVIEW: Hospitalizations for COVID-19 dramatically increase with age. This is likely because of increases in fragility across biological repair systems and a weakened immune system, including loss of the cardiorenal protective arm of the renin--angiotensin system (RAS), composed of angiotensin-converting enzyme-2 (ACE2)/angiotensin-(1--7) [Ang-(1--7)] and its actions through the Mas receptor. The purpose of this review is to explore how cardiac ACE2 changes with age, cardiac diseases, comorbid conditions and pharmaceutical regimens in order to shed light on a potential hormonal unbalance facilitating SARs-CoV-2 vulnerabilities in older adults. RECENT FINDINGS: Increased ACE2 gene expression has been reported in human hearts with myocardial infarction, cardiac remodeling and heart failure. We also found ACE2 mRNA in atrial appendage tissue from cardiac surgical patients to be positively associated with age, elevated by certain comorbid conditions (e.g. COPD and previous stroke) and increased in conjunction with patients' chronic use of antithrombotic agents and thiazide diuretics but not drugs that block the renin--angiotensin system. SUMMARY: Cardiac ACE2 may have bifunctional roles in COVID-19 as ACE2 not only mediates cellular susceptibility to SARS-CoV-2 infection but also protects the heart via the ACE2/Ang-(1--7) pathway. Linking tissue ACE2 from cardiac surgery patients to their comorbid conditions and medical regimens provides a unique latform to address the influence that altered expression of the ACE2/Ang-(1-7)/Mas receptor axis might have on SARs-CoV-2 vulnerability in older adults.

Differential Expression of the Angiotensin-(1-12)/Chymase Axis in Human Atrial Tissue.

BACKGROUND: Heart chymase rather than angiotensin (Ang)-converting enzyme has higher specificity for Ang I conversion into Ang II in humans. A new pathway for direct cardiac Ang II generation has been revealed through the demonstration that Ang-(1-12) is cleaved by chymase to generate Ang II directly. Herein, we address whether Ang-(1-12), chymase messenger RNA (mRNA), and activity levels can be differentiated in human atrial tissue from normal and diseased hearts and if these measures associate with various pathologic heart conditions. MATERIALS AND METHODS: Atrial appendages were collected from 11 nonfailing donor hearts and 111 patients undergoing heart surgery for the correction of valvular heart disease, resistant atrial fibrillation, or ischemic heart disease. Chymase mRNA was analyzed by real-time polymerase chain reaction and enzymatic activity by high-performance liquid chromatography using Ang-(1-12) as the substrate. Ang-(1-12) levels were determined by immunohistochemical staining. RESULTS: Chymase gene transcripts, chymase activity, and immunoreactive Ang-(1-12) expression levels were higher in left atrial tissue compared with right atrial tissue, irrespective of cardiac disease. In addition, left atrial chymase mRNA expression was significantly higher in stroke versus nonstroke patients and in cardiac surgery patients who had a history of postoperative atrial fibrillation versus nonatrial fibrillation. Correlation analysis showed that left atrial chymase mRNA was positively related to left atrial enlargement, as determined by echocardiography. CONCLUSIONS: As Ang-(1-12) expression and chymase gene transcripts and enzymatic activity levels were positively linked to left atrial size in patients with left ventricular heart disease, an important alternate Ang II forming pathway, via Ang-(1-12) and chymase, in maladaptive atrial and ventricular remodeling in humans is uncovered.

Assessment of the prognostic significance of low gradient severe aortic stenosis and preserved left ventricular function requires the integration of the consistency of stroke volume calculation and clinical data.

BACKGROUND: This study was to evaluate the prognostic significance of low gradient severe aortic stenosis (LG SAS) and preserved left ventricular ejection fraction (LVEF) with the integration of echocardiographic and clinical data. METHODS: The study included 172 patients with LG SAS (AVAi ≤ 0.6 cm2 /m2 , mean aortic pressure gradient < 40 mm Hg) and LVEF (≥ 50%). LV outflow tract diameters were measured at both the aortic valve annulus and 5 mm below the annulus for the measurement consistency. Patients were divided into the low flow LG SAS (LF/LG SAS: SVi < 35mL/m2 and AVAi ≤ 0.6 cm2 /m2 ) and normal-flow LG SAS groups (NF/LG SAS: SVi ≥ 35mL/m2 and AVAi ≤ 0.6 cm2 /m2 ). Echocardiographic findings and clinical data were systematically analyzed with mean follow-up of 3.0 ± 1.6 years. RESULTS: LF/LG SAS had significantly smaller AVAi, lower SVi, a higher prevalence of atrial fibrillation (28% vs 12% P = .01) and diabetes (47% vs 27% P = .007) and lower 3-year cumulative survival than NF/LG SAS. Multivariable analysis showed that dyspnea, renal dysfunction (CI 1.42-3.99, P < .01), left atrial diameter, and SVi were independently associated with an increased risk for all-cause mortality. Aortic valve intervention (AVI) improved survival in LF/LG SAS (68% vs 48%, P < .05) in comparison with medical management (HR: 4.20, CI: 1.12-15.76, P = .03), but only modestly in NF/LG SAS (75% vs 65% P > .05). CONCLUSION: Outcome of LG SAS was independently associated with clinical characteristics. AVI likely improved outcome of LF/LG SAS who had high-risk clinical characteristics and unfavorable echocardiographic findings.

Novel Cardiac Intracrine Mechanisms Based on Ang-(1-12)/Chymase Axis Require a Revision of Therapeutic Approaches in Human Heart Disease.

PURPOSE OF THE REVIEW: Drugs targeting the renin-angiotensin system (RAS), namely angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers, are the most commonly prescribed drugs for patients with or at risk for cardiovascular events. However, new treatment strategies aimed at mitigating the rise of the heart failure pandemic are warranted because clinical trials show that RAS blockers have limited benefits in halting disease progression. The main goal of this review is to put forward the concept of an intracrine RAS signaling through the novel angiotensin-(1-12)/chymase axis as the main source of deleterious angiotensin II (Ang II) in cardiac maladaptive remodeling leading to heart failure (HF). RECENT FINDINGS: Expanding traditional knowledge, Ang II can be produced in tissues independently from the circulatory renin-angiotensin system. In the heart, angiotensin-(1-12) [Ang-(1-12)], a recently discovered derivative of angiotensinogen, is a precursor of Ang II, and chymase rather than ACE is the main enzyme contributing to the direct production of Ang II from Ang-(1-12). The Ang-(1-12)/chymase axis is an independent intracrine pathway accounting for the trophic, contractile, and pro-arrhythmic Ang II actions in the human heart. Ang-(1-12) expression and chymase activity have been found elevated in the left atrial appendage of heart disease subjects, suggesting a pivotal role of this axis in the progression of HF. Recent meta-analysis of large clinical trials on the use of ACE inhibitors and angiotensin receptor blockers in cardiovascular disease has demonstrated an imbalance between patients that significantly benefit from these therapeutic agents and those that remain at risk for heart disease progression. Looking to find an explanation, detailed investigation on the RAS has unveiled a previously unrecognized complexity of substrates and enzymes in tissues ultimately associated with the production of Ang II that may explain the shortcomings of ACE inhibition and angiotensin receptor blockade. Discovery of the Ang-(1-12)/chymase axis in human hearts, capable of producing Ang II independently from the circulatory RAS, has led to the notion that a tissue-delimited RAS signaling in an intracrine fashion may account for the deleterious effects of Ang II in the heart, contributing to the transition from maladaptive cardiac remodeling to heart failure. Targeting intracellular RAS signaling may improve current therapies aimed at reducing the burden of heart failure.

Angiotensin-(1-12): a chymase-mediated cellular angiotensin II substrate.

The classical view of biochemical pathways for the formation of biologically active angiotensins continues to undergo significant revision as new data uncovers the existence of important species differences between humans and rodents. The discovery of two novel substrates that, cleaved from angiotensinogen, can lead to direct tissue angiotensin II formation has the potential of radically altering our understanding of how tissues source angiotensin II production and explain the relative lack of efficacy that characterizes the use of angiotensin converting enzyme inhibitors in cardiovascular disease. This review addresses the discovery of angiotensin-(1-12) as an endogenous substrate for the production of biologically active angiotensin peptides by a non-renin dependent mechanism and the revealing role of cardiac chymase as the angiotensin II convertase in the human heart. This new information provides a renewed argument for exploring the role of chymase inhibitors in the correction of cardiac arrhythmias and left ventricular systolic and diastolic dysfunction.

Five-Year Follow-Up from the CoreValve Expanded Use Transcatheter Aortic Valve-in-Surgical Aortic Valve Study.

Transcatheter aortic valve replacement (TAVR) provides an option for extreme-risk patients who underwent reoperation for a failed surgical aortic bioprosthesis. Long-term data on patients who underwent TAVR within a failed surgical aortic valve (TAV-in-SAV) are limited. The CoreValve Expanded Use Study evaluated patients at extreme surgical risk who underwent TAV-in-SAV. Outcomes at 5 years were analyzed by SAV failure mode (stenosis, regurgitation, or combined). Echocardiographic outcomes are site-reported. TAV-in-SAV was attempted in 226 patients with a mean age of 76.7 ± 10.8 years; 63.3% were male, the Society of Thoracic Surgeons predicted risk of mortality score was 9.0 ± 6.7%, and 87.5% had a New York Heart Association classification III or IV symptoms. Most of the failed surgical bioprostheses were stented (81.9%), with an average implant duration of 10.2 ± 4.3 years. The 5-year all-cause mortality or major stroke rate was 47.2% in all patients; 54.4% in the stenosis, 37.6% in the regurgitation, and 38.0% in the combined groups (p = 0.046). At 5 years, all-cause mortality was higher in patients with versus without 30-day severe prosthesis-patient mismatch (51.7% vs 38.3%, p = 0.026). The overall aortic valve reintervention rate was 5.9%; highest in the regurgitation group (12.6%). The mean aortic valve gradient was 14.1 ± 9.8 mm Hg and effective orifice area was 1.57 ± 0.70 at 5 years. Few patients had >mild paravalvular regurgitation at 5 years (5.5% moderate, 0.0% severe). TAV-in-SAV with supra-annular, self-expanding TAVR continues to represent a safe and lasting intermediate option for extreme-risk patients who have appropriate sizing of the preexisting failed surgical valve. Clinical and hemodynamic outcomes were stable through 5 years.

Factor IX complex for the treatment of severe bleeding after cardiac surgery.

BACKGROUND: Previous reports have been published on the use of recombinant Factor VIIa for intractable bleeding after cardiac surgery; however, there is limited information on the use of Factor IX Complex in this population. METHODS: A retrospective cohort study of adult patients who underwent cardiac surgery and experienced severe postoperative bleeding, defined as a mean chest tube output ≥300 mL/h. Primary outcomes were changes in chest tube output and blood product usage pre- and post-Factor IX Complex administration. RESULTS: Eleven patients received Factor IX Complex for severe postoperative bleeding. The mean dose of Factor IX Complex was 35 (13-52) units/kg. Chest tube output was significantly reduced after Factor IX Complex administration (mean pre-Factor IX Complex 381 ± 49 mL/h, mean post-Factor IX Complex 151 ± 38 mL/h; P = 0.003). Blood product usage decreased after Factor IX Complex but was not statistically significant (mean pre-Factor IX Complex 373 ± 81 mL/h, mean post-Factor IX Complex 212 ± 48 mL/h; P = 0.669). Adverse events included 1 pulmonary embolism (postoperative day 43) and 2 episodes of acute renal failure requiring dialysis (postoperative days 2 and 5). CONCLUSIONS: In this small group of patients, Factor IX Complex effectively controlled severe bleeding after cardiac surgery preventing the need for re-exploration.

Anomalous left coronary artery from the pulmonary arteryin an adult.

Anomalous left coronary artery from the pulmonary artery (ALCAPA) is a rare congenital heart defect that usually presents before the age of 1 year. Several surgical options exist for the correction of ALCAPA; however, debate continues regarding the optimal repair technique in adult populations. We report the case of successful surgical repair of ALCAPA with a direct aortic implantation technique in a 44-year-old mother of 4 children.

Cannula design reduces particulate and gaseous emboli during cardiopulmonary bypass for coronary revascularization.

PURPOSE: The incidence of neurocognitive deficits after coronary bypass surgery remains problematic, with atheroembolism being one of the major causes. External manipulation of aorta and the "sandblasting" effect of the high-velocity perfusion jet can cause dislodgement of atheromatous debris. DESCRIPTION: A new arterial cannula features a tip configuration that diffuses the flow through multiple outlets, providing reduced velocity and shear with one central and three diverted flow streams. EVALUATION: Between March 2007 and July 2008 twenty patients having isolated coronary artery bypass operations were instrumented with an Embolus Detection and Classification transducer. These data were compared to 43 patients from a previous study using similar techniques except for a standard open-tip arterial cannula. Total embolic counts were markedly lower in the new cannula group (20±25 vs 174±378) as were both gaseous (11±15 vs 95±211) and particulate counts (9±11 vs 80±194). CONCLUSIONS: The select 3D cannula design reduces the sandblasting effect of the perfusion jet and, also, may direct emboli from the heart and cardiopulmonary bypass equipment away from the cerebral circulation.

Echocardiography and EuroSCORE II for the stratification of low-gradient severe aortic stenosis and preserved left ventricular ejection fraction.

The purpose of this study was to explore the utility of echocardiography and the EuroSCORE II in stratifying patients with low-gradient severe aortic stenosis (LG SAS) and preserved left ventricular ejection fraction (LVEF ≥ 50%) with or without aortic valve intervention (AVI). The study included 323 patients with LG SAS (aortic valve area ≤ 1.0 cm2 and mean pressure gradient < 40 mmHg). Patients were divided into two groups: a high-risk group (EuroSCORE II ≥ 4%, n = 115) and a low-risk group (EuroSCORE II < 4%, n = 208). Echocardiographic and clinical characteristics were analyzed. All-cause mortality was used as a clinical outcome during mean follow-up of 2 ± 1.3 years. Two-year cumulative survival was significantly lower in the high-risk group than the low-risk patients (62.3% vs. 81.7%, p = 0.001). AVI tended to reduce mortality in the high-risk patients (70% vs. 59%; p = 0.065). It did not significantly reduce mortality in the low-risk patients (82.8% with AVI vs. 81.2%, p = 0.68). Multivariable analysis identified heart failure, renal dysfunction and stroke volume index (SVi) as independent predictors for mortality. The study suggested that individualization of AVI based on risk stratification could be considered in a patient with LG SAS and preserved LVEF.

Prognostic value of tissue Doppler-Derived E/e' on early morbid events after cardiac surgery.

BACKGROUND: The tissue Doppler-derived surrogate for left ventricular diastolic pressure, E/e', has been used to prognosticate outcome in a variety of cardiovascular conditions. In this study, we determined the relationship of intraoperative E/e' to the use of inotropic support, duration of mechanical ventilation (MV), length of intensive care unit stay (ICU-LOS), and total hospital stay (H-LOS) in patients requiring cardiac surgery. The records of 245 consecutive patients were retrospectively reviewed to obtain 205 patients who had intraoperative transesophageal echocardiography examinations prior to coronary artery bypass grafting and/or valvular surgery. Cox proportional hazards and logistic regression models were used to analyze the relation between intraoperative E/e' or LVEF and early postoperative morbidity (H-LOS, ICU-LOS, and MV) and the probability that a patient would require inotropic support. With adjustments for other predictors (female gender, hypertension, diabetes, history of myocardial infarction, emergency surgery, renal failure, procedure type, and length of aortic cross-clamp time), an elevated E/e' ratio (>or=8) was significantly associated with an increased ICU-LOS (49 versus 41 median h, P = 0.037) and need for inotropic support (P = 0.002) while baseline LVEF was associated with inotropic support alone (P < 0.0001). These data suggest that the tissue Doppler-derived index of left ventricular diastolic filling pressure may be a useful indicator for predicting early morbid events after cardiac surgery, and may even provide additional information from that of baseline LVEF. Further, patients with elevated preoperative E/e' may need more careful peri- and postoperative management than those patients with E/e' <8.

Atrial angiotensin-(1-12)/chymase expression data in patient of heart diseases.

The data presented here are related to the research article entitled "Differential expression of the angiotensin-(1-12) [Ang-(1-12)]/chymase axis in human atrial tissue [1]. We have showed that chymase gene transcripts, chymase activity, and immunoreactive- Ang-(1-12) expression levels were higher in left compared to right atrial tissue, irrespective of cardiac disease. This article presents the echocardiographic characteristics of 111 patients undergoing heart surgery for the correction of valvular heart disease, resistant atrial fibrillation or ischemic heart disease. Left atrial chymase mRNA expression and activity, and left atrial Ang-(1-12) levels were compared between patients with stroke vs. non-stroke, congestive heart failure vs. non-heart failure, and in cardiac surgery patients who had a history of postoperative atrial fibrillation vs. non-atrial fibrillation.

Effects of a waiting period after clopidogrel treatment before performing coronary artery bypass grafting.

STUDY OBJECTIVE: To assess the effects of a waiting period after clopidogrel treatment before coronary artery bypass grafting (CABG). Design. Single-center, prospective, observational study. SETTING: Cardiothoracic surgery intensive care unit at a university-affiliated medical center. PATIENTS: One hundred consecutive patients who received clopidogrel and were scheduled to undergo primary CABG. In 64 of these patients, CABG was delayed at least 5 days after clopidogrel treatment (group A). The other 36 patients received clopidogrel treatment within 5 days of undergoing CABG (group B). MEASUREMENTS AND MAIN RESULTS: Data were collected on patient demographics, time of last clopidogrel dose, preoperative anticoagulant and/or antiplatelet agents administered, surgical characteristics, intraoperative transfusions, blood products transfused, and chest tube output for 24 hours after surgery. No significant differences in baseline characteristics or intraoperative variables (number of bypasses, aortic cross-clamp time, and cardiopulmonary bypass time) were noted between the two groups. Mean +/- SD number of packed red blood cell units/patient was 1.1 +/- 1.4 in group A versus 2.1 +/- 2.5 in group B (p=0.009). Mean +/- SD number of platelet units/patient transfused was 0.5 +/- 0.9 in group A versus 1.9 +/- 1.6 in group B (p<0.001). When comparing a subset of 21 patients who received clopidogrel within 72 hours of surgery with the 64 whose CABG was delayed at least 5 days after clopidogrel treatment, the transfusion rates were significantly higher (95% vs 52%, p<0.05). Specifically, the mean +/- SD number of transfused units/patient of red blood cells (3.1 +/- 2.8 vs 1.1 +/- 1.4, p<0.005) and platelets (2.6 +/- 1.5 vs 0.5 +/- 0.9, p<0.007) was greater in patients who received clopidogrel within 72 hours of surgery. CONCLUSION: A strategy to delay CABG after clopidogrel treatment led to reduced blood product administration. The optimal waiting period after clopidogrel treatment is not known but appears to be at least 5 days before CABG.

Freedom from structural valve deterioration among patients aged < or = 60 years undergoing Freestyle stentless aortic valve replacement.

BACKGROUND AND AIM OF THE STUDY: Certain theoretical arguments suggest that a stentless bioprosthetic valve may be less subject to calcification and degeneration compared to an equivalent stented bioprosthesis. The study aim was to define the long-term clinical outcomes, including freedom from structural valve deterioration (SVD), among relatively younger patients after aortic valve replacement (AVR) with the Freestyle aortic bioprosthesis. METHODS: A total of 725 patients at eight study sites underwent AVR with the Freestyle stentless aortic bioprosthesis. Of these patients, 57 (7.9%) were aged < or = 60 years at the time of surgery. All clinical data were recorded prospectively. RESULTS: The total follow up for the group was 4,900 patient-years; the mean follow up per patient was 6.8 +/- 3.6 years; median 7.2 years; range: 0 to 13.3 years). Survival at 12 years was 65.0 +/- 11.6% for patients aged < or = 60 years at implant, and 33.1 +/- 5.3% for those aged > or = 61 years. Freedom from cardiac death was 94.6 +/- 6.6% and 70.7 +/- 7.5%, respectively. Freedom from SVD at 12 years was 92.4 +/- 8.0% for patients aged < or = 60 years at implant, and 92.3 +/- 5.0% for those aged > or = 61 years (p = 0.58). There was no significant difference in freedom from reoperation at 12 years between the younger and older age groups (p = 0.16). CONCLUSION: The Freestyle stentless aortic bioprosthesis was associated with excellent clinical outcomes through 12 years of follow up. Freedom from cardiac death was excellent. Measures of bioprosthesis durability remained outstanding through 12 years, with no difference in freedom from SVD or from reoperation between patients aged < or = 60 years and those aged > or = 61 years at the time of implant. Inasmuch as valve durability may influence decisions between a tissue and a mechanical valve in younger patients, these data help to support use of the Freestyle valve in patients aged < or = 60 years.

Extracellular matrix for repair of type IV laryngotracheo-esophageal cleft.

Type IV laryngotracheo-esophageal cleft (LTEC) extending to the level of the carina presents unique challenges to operative repair, particularly with respect to soft tissue durability. This is the first report of CorMatrix(®) extra-cellular matrix (ECM) material use as an interposition graft in a four-layered LTEC repair. At day seven post-operatively, there was epithelialization along the surface of the trachea. At 3 months, she was stable for tracheotomy. At 6 months, the posterior wall resembled completely native tissue. CorMatrix(®) ECM(®) use intra-operatively and post-operative outcome were both highly satisfactory. No adverse reaction was seen in this case through 12-month follow up.

Differential expression of the angiotensin-(1-12)/chymase axis in human atrial tissue.

OBJECTIVE: Heart chymase rather than angiotensin converting enzyme has higher specificity for angiotensin (Ang) I conversion into Ang II in humans. A new pathway for direct cardiac Ang II generation has been revealed through the demonstration that Ang-(1-12) is cleaved by chymase to generate Ang II directly. We address here whether Ang-(1-12) and chymase gene expression and activity are detected in the atrial appendages of 44 patients (10 females) undergoing heart surgery for the correction of valvular heart disease, resistant atrial fibrillation or ischemic heart disease. METHODS AND RESULTS: Immunoreactive Ang-(1-12) expression was 54% higher in left atrial compared with right atrial appendages. This was associated with higher abundance of left atrial appendage chymase gene transcripts and chymase activity, but no differences in angiotensinogen mRNA. Atrial chymase enzymatic activity was highly correlated with left atrial but not right atrial enlargement as determined by echocardiography, while both tyrosine hydroxylase and neuropeptide Y atrial appendage mRNAs correlated with atrial angiotensinogen mRNAs. CONCLUSIONS: Higher Ang-(1-12) expression and upregulation of chymase gene transcripts and enzymatic activity from the atrial appendages connected to the enlarged left versus right atrial chambers of subjects with left heart disease defines a role of this alternate Ang II forming pathway in the processes accompanying adverse atrial and ventricular remodeling.