Surgical Technique And Clinical Implications Of Transcatheter Aortic Valve Bioprosthesis Explantation.

There has been a worldwide rapid adoption of transcatheter aortic valve replacement (TAVR) as an alternative to surgical aortic valve replacement (SAVR) for patients with severe aortic stenosis. Currently, more TAVR explants with SAVRs are performed than TAVR-in TAV. TAVR explantation is a technically hazardous procedure mainly due to significant aortic neo-endothelialization which incorporates the TAVR valve. Surgical techniques for TAVR explantation are not well established and surgeon experience at present is limited. In this manuscript, we describe our technique for surgical explantation of transcatheter aortic bioprosthesis. Familiarity with the procedure and its clinical implications is essential for all cardiac surgeons.

Ventilatory Failure And Pulmonary Embolism In Covid-19 Requiring Enhanced Venous Drainage For Extracorporeal Membrane Oxygenation.

COVID-19 infection manifests as a spectrum of respiratory and vascular complications, including acute respiratory distress syndrome (ARDS) and pulmonary embolism. Herein, we describe a case of a healthy young male who presented with ARDS refractory to mechanical ventilation and concomitant bilateral pulmonary emboli managed with extracorporeal membrane oxygenation (ECMO) and embolectomy. The embolectomy and initial veno-venous ECMO configuration failed to correct the patient's hypoxemia despite maximal flows. This was thought to be due to a high-output state secondary to vasodilatory shock preventing adequate drainage from the existing single drainage ECMO cannulation, following which a second venous cannula was placed to form a unique veno-veno-venous ECMO circuit that resolved the persistent hypoxemia. The case underscores the importance of identifying embolic events and vasodilatory shock in COVID-19 patients, both of which need to be addressed simultaneously to avoid worsening right ventricular failure (via both mechanical and hypoxia-driven pathways) and the resulting veno-arterial ECMO along with its associated complications.

Survey of Contemporary Cardiac Surgery Intensive Care Unit Models in the United States.

BACKGROUND: Intensive care unit (ICU) structure and intensive care physician staffing (IPS) models are thought to influence outcomes after cardiac surgery. Given limited information on staffing in the cardiothoracic ICU, The Society of Thoracic Surgeons Workforce on Critical Care undertook a survey to describe current IPS models. We hypothesized that variability would exist throughout the United States. METHODS: A survey was sent to The Society of Thoracic Surgeons centers in the United States. Center case volume, ICU census, procedure profiles, and the primary specialties of consultants were queried. Definitions of IPS models were open (managed by cardiac surgeons), closed (all decisions made by dedicated intensivists 7 days a week), or semiopen (intensivist attends 5-7 days a week with surgeons cosharing management). Experience level of bedside providers and after-hours provider coverage were also assessed. RESULTS: Of the 965 centers contacted, 148 (15.3%) completed surveys. Approximately 41% of reporting centers used a dedicated cardiothoracic ICU for immediate postoperative management. The most common IPS model was open (47%), followed by semiopen (41%) and closed (12%). The primary specialties of intensivists varied, with pulmonary medicine/critical care being predominant (67%). Physician assistants were the most common after-hours provider (44%). More than one-third of responding centers described having no house staff, other than bedside nurses, for nighttime coverage. CONCLUSIONS: Cardiothoracic ICU models vary widely in the United States, with almost half being open, often with no in-house coverage. In-house nighttime coverage was (1) not driven by case complexity and (2) most commonly provided by a physician assistant. Clinical outcomes associated with different ISPS models require further evaluation.

Heparin-Sparing Anticoagulation Strategies Are Viable Options for Patients on Veno-Venous ECMO.

BACKGROUND: Extracorporeal membrane oxygenation (ECMO), a rescue therapy for pulmonary failure, has traditionally been limited by anticoagulation requirements. Recent practice has challenged the absolute need for anticoagulation, expanding the role of ECMO to patients with higher bleeding risk. We hypothesize that mortality, bleeding, thrombotic events, and transfusions do not differ between heparin-sparing and full therapeutic anticoagulation strategies in veno-venous (VV) ECMO management. MATERIALS AND METHODS: Adult VV ECMO patients between October 2011 and May 2018 at a single center were reviewed. A heparin-sparing strategy was implemented in October 2014; we compared outcomes in an as-treated fashion. The primary end point was survival. Secondary end points included bleeding, thrombotic complications, and transfusion requirements. RESULTS: Forty VV ECMO patients were included: 17 (147 circuit-days) before and 23 (214 circuit-days) after implementation of a heparin-sparing protocol. Patients treated with heparin-sparing anticoagulation had a lower body mass index (28.5 ± 7.1 versus 38.1 ± 12.4, P = 0.01), more often required inotropic support before ECMO (82 versus 50%, P = 0.05), and had a lower mean activated clotting time (167 ± 15 versus 189 ± 15 s, P < 0.01). There were no significant differences in survival to decannulation (59 versus 83%, P = 0.16) or discharge (50 versus 72%, P = 0.20), bleeding (32 versus 33%, P = 1.0), thromboembolic events (18 versus 39%, P = 0.17), or transfusion requirements (median 1.1 versus 0.9 unit per circuit-day, P = 0.48). CONCLUSIONS: Survival, bleeding, thrombotic complications, and transfusion requirements did not differ between heparin-sparing and full therapeutic heparin strategies for management of VV ECMO. VV ECMO can be a safe option in patients with traditional contraindications to anticoagulation.

Implementation of a standardized handoff protocol for post-operative admissions to the surgical intensive care unit.

BACKGROUND: The transfer of critically ill patients from the operating room (OR) to the surgical intensive care unit (SICU) involves handoffs between multiple providers. Incomplete handoffs lead to poor communication, a major contributor to sentinel events. Our aim was to determine whether handoff standardization led to improvements in caregiver involvement and communication. METHODS: A prospective intervention study was designed to observe thirty one patient handoffs from OR to SICU for 49 critical parameters including caregiver presence, peri-operative details, and time required to complete key steps. Following a six month implementation period, thirty one handoffs were observed to determine improvement. RESULTS: A significant improvement in presence of physician providers including intensivists and surgeons was observed (p = 0.0004 and p < 0.0001, respectively). Critical details were communicated more consistently, including procedure performed (p = 0.0048), complications (p < 0.0001), difficult airways (p < 0.0001), ventilator settings (p < 0.0001) and pressor requirements (p = 0.0134). Conversely, handoff duration did not increase significantly (p = 0.22). CONCLUSIONS: Implementation of a standardized protocol for handoffs between OR and SICU significantly improved caregiver involvement and reduced information omission without affecting provider time commitment.

Hypertensive crisis secondary to pheochromocytoma.

Pheochromocytoma is an uncommon tumor of the adrenal glands that can present with headaches, sweating, palpitations, and paroxysmal hypertension. Pheochromocytoma crisis can lead to cardiomyopathy, pulmonary edema, and even total circulatory collapse. We describe a patient with hypoxic respiratory failure requiring extracorporeal membrane oxygenation to stabilize until the pheochromocytoma was discovered and treated.

Angiosarcoma of the right atrium presenting as hemoptysis.

This case report describes a previously healthy 32-year-old man who presented with several weeks of hemoptysis. Initially he was treated with antibiotics with a preliminary diagnosis of pneumonia. With increasing hemoptysis and additional symptoms, he was referred to our institution. Cardiac magnetic resonance imaging suggested a diagnosis of right atrial angiosarcoma with extensive pulmonary metastases. His extensive pulmonary tumor burden caused the hemoptysis. Pulmonary biopsy was well tolerated, and he was referred to medical oncology for adjuvant therapy. Following the first cycle of chemotherapy, his hemoptysis lessened.

A standard handoff improves cardiac surgical patient transfer: operating room to intensive care unit.

BACKGROUND: Patient handoffs are high-risk times associated with sentinel events. Effective handoff processes may enhance patient safety and team member communication. This study assesses the impact of a standardized protocol for handoffs from the cardiac surgery operating room to intensive care unit (ICU). METHODS: Using a prospective pre-post study design, a formalized handoff process was developed including critical handoff elements and a standardized handoff procedure, script, and checklist. Data were collected from 60 handoff observations (30 pre and 30 post), evaluating 52 unique parameters, and survey of providers on perspectives of the handoff process. Results were compared by chi-square test, two sample t-test, or nonparametric Mann-Whitney test. Statistical significance was defined as P ≤ .05. RESULTS: Provider's perspectives showed improved satisfaction with the standardized handoff process through improved responses in 19 of 22 survey items (P < .001). Median time until ventilator connection, ICU monitor transfer, first cardiac index, and chest radiograph were reduced after implementation. Completion of handoff process components also improved after implementation for 36 of 47 nontime parameters. CONCLUSIONS: A standard checklist-driven handoff process can dramatically improve key data transmission and reduce time of critical patient care steps during the high-risk period of patient handoff in a cardiac surgical ICU.

Consequence of patient substitution of nattokinase for warfarin after aortic valve replacement with a mechanical prosthesis.

This report describes a patient's self-substitution of nattokinase for the vitamin K antagonist warfarin after aortic valve replacement with a mechanical prosthesis. Nattokinase is an enzyme derived from a popular fermented soybean preparation in Japan (natto), which has fibrinolytic properties and is gaining popularity in nontraditional health journals and nonmedical health websites as an over-the-counter thrombolytic. After nearly a year of use of nattokinase without warfarin, the patient developed thrombus on the mechanical valve and underwent successful repeat valve replacement. We believe this is the first documented case of nattokinase being used as a substitute for warfarin after valve replacement, and we strongly discourage its use for this purpose.

Cardiac surgical ICU care: eliminating "preventable" complications.

The goal of this article is to provide an outline of the latest advances in critical care that pertain to the open heart surgery patient, pinpointing initiatives that would enable physicians and institutions to successfully implement guidelines, protocols, checklists, and initiatives that have been shown to improve patient safety.

Anticoagulation for mechanical heart valves: a role for patient based therapy.

Anticoagulation management issues following mechanical cardiac valve replacement revolve around target levels for chronic oral anticoagulation. While these levels are important, they are only one aspect of a follow-up process that should be individualized to each patient with a mechanical cardiac valve and coupled with patient education, risk factor modification, and long-term follow-up. It is difficult to separate patient related risk factors, those traditional risk factors that markedly increase the incidence of potential valve related events (i.e., atrial fibrillation), and yet other more subtle non-traditional risk factors for thromboembolism (i.e., smoking and hypertension) that contribute to events. These also require management during the post-operative period and long-term follow-up. There are also different risk factors for anatomic valve position. The aortic valve is the safest of all the anatomic positions regarding valve related events. The mitral valve is at higher risk and the tricuspid valve is the most risky anatomic position. Anticoagulation related hemorrhage is the most dangerous event for mortality and morbidity in the aortic position, thromboembolism in the mitral position, and valve thrombosis in the tricuspid position. Each of these requires different degrees of patient modification and target levels for anticoagulation. Additionally, low risk patients with aortic valve replacement may not require anticoagulant therapy at all. Rather, treatment with modern, highly potent platelet inhibiting drugs may be effective after a period of sewing ring endothelialization under the protection of antithrombotic therapy. Each of these aspects and risk factors is discussed, as well as the call for prospective randomized trials treating low risk patients with anti-platelet drugs versus warfarin anticoagulation.

The St. Jude Medical cardiac valve prosthesis: long-term follow up of patients having double valve replacement.

BACKGROUND AND AIM OF THE STUDY: Between October 1977 and February 2002, a total of 343 patients (mean age 62 +/- 13 years; range: 19-91 years) underwent double valve replacement (DVR) with the St. Jude Medical (SJM) heart valve. Among the replacements, 337 (98%) were aortic and mitral in nature. Concomitant coronary artery bypass was performed in 73 patients (21%). METHODS: Cardiac Surgical Associates has maintained an independent database of patients undergoing valve replacement with the SJM prosthesis since the valve's first implantation in October 1977. Patients were contacted by questionnaire and/or telephone (94% complete) between November 2002 and June 2003. The patients' hospital course and valve-related events were verified by patient chart review and/or physician contact. RESULTS: Operative mortality was 8% (n = 29); mortality was valve-related in two cases. The mean follow up was 6.5 +/- 6.0 years (range: 1 month to 24 years); total follow up was 2,226 patient-years. Over 25 years, patient freedom from late mortality was 62%, and from valve-related mortality 78%. Freedom from thromboembolic events was 82% (93% from permanent defect), from bleeding events 76%, from endocarditis 98%, from valve thrombosis 99.9%, and from reoperation 98%. Six reoperations were carried out in five patients (2%), valve repair or replacement in five (2%), and suture closure of paravalvular leak in one patient (0.3%). There were no valve structural failures reported. CONCLUSION: The SJM valve has proven to be an effective and durable heart valve prosthesis. Over the long-term, the event rate is low and there is excellent freedom from reoperation in the double valve configuration.

Effect of NADPH oxidase inhibition on cardiopulmonary bypass-induced lung injury.

Cardiopulmonary bypass (CPB) causes acute lung injury. Reactive oxygen species (ROS) from NADPH oxidase may contribute to this injury. To determine the role of NADPH oxidase, we pretreated pigs with structurally dissimilar NADPH oxidase inhibitors. Low-dose apocynin (4-hydroxy-3-methoxy-acetophenone; 200 mg/kg, n = 6), high-dose apocynin (400 mg/kg, n = 6), or diphenyleneiodonium (DPI; 8 mg/kg) was compared with diluent (n = 8). An additional group was treated with indomethacin (10 mg/kg, n = 3). CPB was performed for 2 h with deflated lungs, complete pulmonary artery occlusion, and bronchial artery ligation to maximize lung injury. Parameters of pulmonary function were evaluated for 25 min following CPB. Blood chemiluminescence indicated neutrophil ROS production. Electron paramagnetic resonance determined the effect of apocynin and DPI on in vitro pulmonary endothelial ROS production following hypoxia-reoxygenation. Both apocynin and DPI attenuated blood chemiluminescence and post-CPB hypoxemia. At 25 min post-CPB with Fi(O(2)) = 1, arterial Po(2) (Pa(o(2))) averaged 52 +/- 5, 162 +/- 54, 335 +/- 88, and 329 +/- 119 mmHg in control, low-dose apocynin, high-dose apocynin, and DPI-treated groups, respectively (P < 0.01). Indomethacin had no effect. Pa(O(2)) correlated with blood chemiluminescence measured after drug administration before CPB (R = -0.60, P < 0.005). Neither apocynin nor DPI prevented the increased tracheal pressure, plasma cytokine concentrations (tumor necrosis factor-alpha and IL-6), extravascular lung water, and pulmonary vascular protein permeability observed in control pigs. NADPH oxidase inhibition, but not xanthine oxidase inhibition, significantly blocked endothelial ROS generation following hypoxia-reoxygenation (P < 0.05). NADPH oxidase-derived ROS contribute to the severe hypoxemia but not to the increased cytokine generation and pulmonary vascular protein permeability, which occur following CPB.

Effect of bronchial artery blood flow on cardiopulmonary bypass-induced lung injury.

Cardiovascular surgery requiring cardiopulmonary bypass (CPB) is frequently complicated by postoperative lung injury. Bronchial artery (BA) blood flow has been hypothesized to attenuate this injury. The purpose of the present study was to determine the effect of BA blood flow on CPB-induced lung injury in anesthetized pigs. In eight pigs (BA ligated) the BA was ligated, whereas in six pigs (BA patent) the BA was identified but left intact. Warm (37 degrees C) CPB was then performed in all pigs with complete occlusion of the pulmonary artery and deflated lungs to maximize lung injury. BA ligation significantly exacerbated nearly all aspects of pulmonary function beginning at 5 min post-CPB. At 25 min, BA-ligated pigs had a lower arterial Po(2) at a fraction of inspired oxygen of 1.0 (52 +/- 5 vs. 312 +/- 58 mmHg) and greater peak tracheal pressure (39 +/- 6 vs. 15 +/- 4 mmHg), pulmonary vascular resistance (11 +/- 1 vs. 6 +/- 1 mmHg x l(-1) x min), plasma TNF-alpha (1.2 +/- 0.60 vs. 0.59 +/- 0.092 ng/ml), extravascular lung water (11.7 +/- 1.2 vs. 7.7 +/- 0.5 ml/g blood-free dry weight), and pulmonary vascular protein permeability, as assessed by a decreased reflection coefficient for albumin (sigma(alb); 0.53 +/- 0.1 vs. 0.82 +/- 0.05). There was a negative correlation (R = 0.95, P < 0.001) between sigma(alb) and the 25-min plasma TNF-alpha concentration. These results suggest that a severe decrease in BA blood flow during and after warm CPB causes increased pulmonary vascular permeability, edema formation, cytokine production, and severe arterial hypoxemia secondary to intrapulmonary shunt.

Pharmacological preconditioning ameliorates neurological injury in a model of spinal cord ischemia.

BACKGROUND: Pharmacological openers of mitochondrial ATP-sensitive potassium (mitoKATP) channels have been shown to mimic ischemic preconditioning (IPC) in both the brain and myocardium. We hypothesized that similar endogenous mechanisms exist in the spinal cord and that diazoxide, a potent mitoKATP opener, could reduce neurologic injury after aortic cross-clamping in a model of spinal cord ischemia. METHODS: The infra-renal aorta was cross-clamped in 45 male New Zealand white rabbits for 20 minutes. Control animals received no pretreatment. Diazoxide-treated animals were dosed (5 mg/kg) 15 minutes before cross-clamp. A third group underwent 5 minutes of IPC 30 minutes before cross-clamp. Two groups received KATP antagonists, 5-hydroxydecanoic acid (5-HD, 20 mg/kg) or glibenclamide (1.0 mg/kg), before diazoxide administration. Systemic hypotension was induced in a final group with excess isoflurane. Tarlov Scoring was used to assess neurologic function at 24 and 48 hours, after which, the spinal cords were procured for histopathological analysis. RESULTS: Tarlov scoring demonstrated marked improvement in the Diazoxide group compared with control at 24 hours (p < 0.02) and 48 hours (p < 0.009). Moreover, no further neurologic injury occurred in this group at 7 days. IPC-treated animals showed neurologic improvement but were not significantly different from controls. Further, administration of glibenclamide was effective in antagonizing diazoxide's protective effect. CONCLUSIONS: Administration of diazoxide resulted in significant improvement in neurologic outcome in this model. This protective effect improved outcome at both early and late time points. Further, the antagonistic effect of glibenclamide implicates diazoxide's ATP-dependent potassium channel agonism as the mechanism of protection. Overall, this study suggests that diazoxide may be useful in the prevention of neurologic injury after thoracic aneurysm surgery.

Mesenchymal stem cell implantation in a swine myocardial infarct model: engraftment and functional effects.

BACKGROUND: A novel therapeutic option for the treatment of acute myocardial infarction involves the use of mesenchymal stem cells (MSCs). The purpose of this study was to investigate whether implantation of autologous MSCs results in sustained engraftment, myogenic differentiation, and improved cardiac function in a swine myocardial infarct model. METHODS: MSCs were isolated and expanded from bone marrow aspirates of 14 domestic swine. A 60-minute left anterior descending artery occlusion was used to produce anterior wall infarction. Piezoelectric crystals were placed within the ischemic region for measurement of regional wall thickness and contractile function. Two weeks later animals autologous, Di-I-labeled MSCs (6 x 10(7)) were implanted into the infarct by direct injection. Hemodynamic and functional measurements were obtained weekly until the time of sacrifice. Immunohistochemistry was used to assess MSC engraftment and myogenic differentiation. RESULTS: Microscopic analysis showed robust engraftment of MSCs in all treated animals. Expression of muscle-specific proteins was seen as early as 2 weeks and could be identified in all animals at sacrifice. The degree of contractile dysfunction was significantly attenuated at 4 weeks in animals implanted with MSCs (5.4% +/- 2.2% versus -3.37% +/- 2.7% in control). In addition, the extent of wall thinning after myocardial infarction was markedly reduced in treated animals. CONCLUSIONS: Mesenchymal stem cells are capable of engraftment in host myocardium, demonstrate expression of muscle specific proteins, and may attenuate contractile dysfunction and pathologic thinning in this model of left ventricular wall infarction. MSC cardiomyoplasty may have significant clinical potential in attenuating the pathology associated with myocardial infarction.

Transmural atrial insulating lesions using epicardially applied radiofrequency energy coupled with saline irrigation.

The Maze procedure has been demonstrated to eliminate atrial fibrillation (AF) refractory to medical management. The procedure, however, is technically difficult and requires prolonged cardiopulmonary bypass (CPB). We investigated the use of epicardially applied radiofrequency (RF) energy delivered using a saline-irrigated probe to functionally reproduce the linear lesions of the surgical Maze procedure. The goals of this study were to safely produce transmural atrial insulation lines without CPB and to investigate whether they could retain their electrical insulation properties and structural integrity over an acute time period. Baseline pacing thresholds were measured on the atria of six swine. Then, circular insulating lesions (n = 11) were created around each pacing site using a saline-irrigated RF probe and specifically designed radiofrequency generator. Pacing thresholds were repeated at the same atrial sites, and in adjacent areas, immediately following lesion creation and at 7 days. At sacrifice the areas of interest were removed for histopathology. Pacing thresholds increased from 0.9 +/- 0.09 V to 9.59 +/- 0.87 V immediately following lesion formation (p <.05) and remained supraphysiologic at 4.05 +/- 0.36 V after 7 days (p <.05). Thresholds from outside the lesions were unchanged from baseline. There was no evidence of perforation and histologic analysis demonstrated transmural necrosis with advancing granulation tissue. Our data suggest that epicardially applied RF energy coupled with saline irrigation can produce transmural electrical insulation lines for up to 7 days. However, the decreasing trend in thresholds toward baseline suggests further investigation is needed to verify insulation line continuity over a chronic time period. These lines were created safely and efficiently without CPB, and may be applicable to a minimally invasive Maze procedure.

Heterotopic abdominal heart transplantation: a pilot study.

The increasingly severe shortage of donor hearts has prompted a liberalization of what is considered an acceptable donor heart. The use of marginally acceptable organs has increased in recent years. Although these marginal donors have proved effective, there still remains a tremendous shortage of donors to treat the large number of patients who are candidates for cardiac transplantation. Further use of marginal donors is limited by the requirement to assume immediate and full support of the circulation. New strategies are required to increase donor organ use even further. The authors developed a model of heterotopic abdominal heart transplant (HAHT) to investigate the possibility of using marginal donor hearts to expand the donor pool for cardiac transplantation. The authors' goal was to show that HAHT was technically feasible and could potentially function as auxiliary circulatory support in the setting of low cardiac output. The hemodynamic and metabolic consequences of a HAHT were investigated in a pilot study that provides proof of concept and lays the groundwork for future investigations.