Kamrouz Ghadimi

Challenges After the First Decade of Transcatheter Aortic Valve Replacement: Focus on Vascular Complications, Stroke, and Paravalvular Leak

Transcatheter aortic valve replacement (TAVR) is entering its second decade. Three major clinical challenges have emerged from the first decade of experience: vascular complications, stroke, and paravalvular leak (PVL). Major vascular complications remain common and independently predict major bleeding, transfusion, renal failure, and mortality. Although women are more prone to vascular complications, overall they have better survival than men. Further predictors of major vascular complications include heavily diseased femoral arteries and operator experience. Strategies to minimize vascular complications include a multimodal approach and sleeker delivery systems. Although cerebral embolism is very common during TAVR, it mostly is asymptomatic. Major stroke independently predicts prolonged recovery and increased mortality. Identified stroke predictors include functional disability, previous stroke, a transapical approach, and atrial fibrillation. Embolic protection devices are in development to mitigate the risk of embolic stroke after TAVR. PVL is common and significantly decreases survival. Undersizing of the valve prosthesis can be minimized with 3-dimensional imaging by computed tomography or echocardiography to describe the elliptic aortic annulus accurately. The formal grading of PVL severity in TAVR is based on its percentage of the circumferential extent of the aortic valve annulus. Further emerging management strategies for PVL include a repositionable valve prosthesis and transcatheter plugging. The first decade of TAVR has ushered in a new paradigm for the multidisciplinary management of valvular heart disease. The second decade likely will build on this wave of initial success with further significant innovations.

Andexanet alfa for the reversal of Factor Xa inhibitor related anticoagulation

ABSTRACT Andexanet alfa is a specific reversal agent for Factor Xa inhibitors. The molecule is a recombinant protein analog of factor Xa that binds to Factor Xa inhibitors and antithrombin:LMWH complex but does not trigger prothrombotic activity. In ex vivo, animal, and volunteer human studies, andexanet alfa (AnXa) was able to dose-dependently reverse Factor Xa inhibition and restore thrombin generation for the duration of drug administration. Further trials are underway to examine its safety and efficacy in the population of patients experiencing FXa inhibitor-related bleeding.

Atrial Fibrillation After Cardiac Surgery: Clinical Update on Mechanisms and Prophylactic Strategies

ATRIAL FIBRILLATION (AF) is a common complication after cardiac surgery and is associated with increased cost, morbidity, and mortality. Minimally invasive surgical techniques such as transcatheter aortic valve replacement (TAVR) have not substantially reduced the risk of developing AF. The development of AF after cardiac surgery remains common and significantly increases mortality, morbidity, and total hospital costs, including readmission. In an effort to reduce these adverse consequences of this complication, considerable research recently has focused on identifying prophylactic strategies for AF after cardiac surgery. A thorough understanding of the mechanisms underlying the genesis of AF in this setting may aid in designing preventative paradigms and standardizing treatment. The purpose of this expert review is to highlight the incidence, pathogenesis, and preventative strategies for AF after cardiac surgery.

Prothrombin Complex Concentrates for Bleeding in the Perioperative Setting.

Prothrombin complex concentrates (PCCs) contain vitamin K-dependent clotting factors (II, VII, IX, and X) and are marketed as 3 or 4 factor-PCC formulations depending on the concentrations of factor VII. PCCs rapidly restore deficient coagulation factor concentrations to achieve hemostasis, but like with all procoagulants, the effect is balanced against thromboembolic risk. The latter is dependent on both the dose of PCCs and the individual patient prothrombotic predisposition. PCCs are approved by the US Food and Drug Administration for the reversal of vitamin K antagonists in the setting of coagulopathy or bleeding and, therefore, can be administered when urgent surgery is required in patients taking warfarin. However, there is growing experience with the off-label use of PCCs to treat patients with surgical coagulopathic bleeding. Despite their increasing use, there are limited prospective data related to the safety, efficacy, and dosing of PCCs for this indication. PCC administration in the perioperative setting may be tailored to the individual patient based on the laboratory and clinical variables, including point-of-care coagulation testing, to balance hemostatic benefits while minimizing the prothrombotic risk. Importantly, in patients with perioperative bleeding, other considerations should include treating additional sources of coagulopathy such as hypofibrinogenemia, thrombocytopenia, and platelet disorders or surgical sources of bleeding. Thromboembolic risk from excessive PCC dosing may be present well into the postoperative period after hemostasis is achieved owing to the relatively long half-life of prothrombin (factor II, 60–72 hours). The integration of PCCs into comprehensive perioperative coagulation treatment algorithms for refractory bleeding is increasingly reported, but further studies are needed to better evaluate the safe and effective administration of these factor concentrates.

The Functional Aortic Annulus in the 3D Era: Focus on Transcatheter Aortic Valve Replacement for the Perioperative Echocardiographer

The functional aortic annulus represents a sound clinical framework for understanding the components of the aortic root complex. Recent three-dimensional imaging analysis has demonstrated that the aortic annulus frequently is elliptical rather than circular. Comprehensive three-dimensional quantification of this aortic annular geometry by transesophageal echocardiography and/or multidetector computed tomography is essential to guide precise prosthesis sizing in transcatheter aortic valve replacement to minimize paravalvular leak for optimal clinical outcome. Furthermore, three-dimensional transesophageal echocardiography accurately can quantify additional parameters of the functional aortic annulus such as coronary height for complete sizing profiles for all valve types in transcatheter aortic valve replacement. Although it is maturing rapidly as a clinical imaging modality, its role in transcatheter aortic valve replacement is seen best as complementary to multidetector computed tomography in a multidisciplinary heart team model.

Perioperative Conduction Disturbances After Transcatheter Aortic Valve Replacement

Cardiac conduction disturbances after transcatheter aortic valve replacement (TAVR) are common and important. The risk factors and outcome effects of atrial fibrillation after TAVR recently have been appreciated. The paucity of clinical trials has resulted in the absence of clinical guidelines for the management of this important arrhythmia in this high-risk patient population. Given this evidence gap and clinical necessity, it is likely that clinical trials in the near future will be designed and implemented to address these issues. Prompt recognition and proper management of atrioventricular block remain essential in the management of patients undergoing TAVR, because heart block of all types is common and may require permanent pacemaker implantation. The current evidence base has described the incidence, risk factors, and current outcomes of this conduction disturbance in detail. As the practice of TAVR evolves and novel valve prostheses are developed, a focus on minimizing damage to the cardiac conductive system remains paramount. It remains to be seen how the next generation of TAVR prostheses will affect the incidence, risk factors, and clinical outcomes of associated conduction disturbances.

New Frontiers in Aortic Therapy: Focus on Deep Hypothermic Circulatory Arrest

There is currently a paradigm shift in the conduct of adult aortic arch repair. Although deep hypothermic circulatory arrest has been the classic perfusion platform for adult aortic arch repair, recent developments have challenged this aortic arch paradigm. There has been a gradual clinical drift towards moderate, and even mild, hypothermic circulatory arrest combined with antegrade cerebral perfusion. This paradigm shift appears to be associated with equivalent clinical outcomes, and in certain settings, with improved outcomes. The advent of endovascular therapy has challenged even further the concept that circulatory arrest is required for adult aortic arch repair. These dramatic advances have resulted in the emergence of an international aortic arch surgery study group that aims to advance this dynamic field through consensus statements, meta-analysis, clinical database analysis, prospective registries, and randomized controlled trials.

The year in cardiothoracic and vascular anesthesia: selected highlights from 2012.

Cardiothoracic and vascular critical care has emerged as a subspecialty due to procedural breakthroughs, an aging population, and a multidisciplinary collaboration. This subspecialty now has a dedicated professional society, recently published guidelines, and plans for standardized certification. This paradigm shift represents a major collaboration opportunity for our specialty. The rise of evidence-based perioperative practice has produced a culture of large trials in our specialty to search for solutions to the challenging outcome questions. Besides the growth in the development of evidence, the consensus conference format and postpublication peer review have both emerged as effective processes for identifying the most relevant high-quality evidence. The quest for best perioperative practice has highlighted the importance of teamwork at all phases of care with respect to transitions in care, blood component transfusion, and research misconduct. The emergence of ultrasound as a standard for central vascular access also has been emphasized in recent multisociety guidelines. There also has been a paradigm shift in the management of patients with coronary artery disease. Recent guidelines have emphasized the roles of the cardiac anesthesiologist and the interventional cardiologist as part of the heart team approach. Major recent trials in comparative effectiveness have challenged the advantages of percutaneous coronary intervention, off-pump coronary artery bypass surgery, and intra-aortic balloon counterpulsation. The year 2012 has witnessed the emergence of new paradigms of care in our specialty with the emphasis on teamwork, safety, and quality. These processes will further improve perioperative outcome.

The year in cardiothoracic and vascular anesthesia: selected highlights from 2013.

This article reviewed selected research highlights of 2013 that pertain to the specialty of cardiothoracic and vascular anesthesia. The first major theme is the commemoration of the sixtieth anniversary of the first successful cardiac surgical procedure with cardiopulmonary bypass conducted by Dr Gibbon. This major milestone revolutionized the practice of cardiovascular surgery and invigorated a paradigm of mechanical platforms for contemporary perioperative cardiovascular practice. Dr Kolff was also a leading contributor in this area because of his important contributions to the refinement of cardiopulmonary bypass and mechanical ventricular assistance. The second major theme is the diffusion of echocardiography throughout perioperative practice. There are now guidelines and training pathways to guide its generalization into everyday practice. The third major theme is the paradigm shift in perioperative fluid management. Recent large randomized trials suggest that fluids are drugs that require a precise prescription with respect to type, dose, and duration. The final theme is patient safety in the cardiac perioperative environment. A recent expert scientific statement has focused attention on this issue because most perioperative errors are preventable. It is likely that clinical research in this area will blossom because this is a major opportunity for improvement in our specialty. The patient care processes identified in these research highlights will further improve perioperative outcomes for our patients.

Advancing Extubation Time for Cardiac Surgery Patients Using Lean Work Design

BACKGROUND Early extubation in select cardiac surgery patients reduces tracheal intubation times, intensive care unit length of stay, and hospital length of stay. While there is good evidence in the literature to support early extubation, there is very little published research that describes how to study and redesign processes of care to increase early extubation rates. OBJECTIVE To improve rates of early extubation by redesigning patient care processes using Lean principles to remove barriers to desired care and facilitate early extubation with guideline management. DESIGN Retrospective data analysis. SETTING Sixteen-bed intensive care unit in a mid-sized, academic community hospital. PATIENTS Four hundred four patients undergoing coronary artery bypass graft surgery, aortic valve replacement, or mitral valve replacement/repair. INTERVENTION The process of care for cardiac surgery patients, beginning with the immediate preoperative period and ending with extubation in the postoperative period, was analyzed using Lean methodologies. A value stream analysis was performed to identify waste in the process, and root causes for the largest sources of waste were identified. Hypothermia on admission to the intensive care unit, prolonged weaning using arterial blood gas results, hypertension management with pain medications and sedation medications, and delays in obtaining equipment were the primary reasons early extubation was delayed. Process redesign using Lean work design principles was implemented to eliminate these issues. MEASUREMENTS The rate of patients being extubated in fewer than 6 hours and length of intubation. RESULTS One hundred ninety-five pre-intervention subjects were compared with 171 post-intervention subjects. The pre- and post- groups did not differ in demographic predictors (Table 1). The intervention predicted extubation in<6 hours (pre-intervention 27% versus post-intervention 50%, p = 0.0001). Age, renal failure, and gender also predicted whether intubation occurred within 6 hours. The median length of intubation was lower post-intervention (pre-intervention 9.7 v post-intervention 6.1 hours, p = 0.0019) LIMITATIONS: The effect of this nonrandomized intervention could be due to other factors associated with a different care epoch. CONCLUSIONS The closely planned, coordinated, and integrated care paradigm dramatically increased the likelihood of extubation within 6 hours of arrival in the SICU.