ATP-Sensitive Potassium Channel Opener Diazoxide Reduces Myocardial Stunning in a Porcine Regional With Subsequent Global Ischemia Model.

Background ATP-sensitive potassium channels are inhibited by ATP and open during metabolic stress, providing endogenous myocardial protection. Pharmacologic opening of ATP potassium channels with diazoxide preserves myocardial function following prolonged global ischemia, making it an ideal candidate for use during cardiac surgery. We hypothesized that diazoxide would reduce myocardial stunning after regional ischemia with subsequent prolonged global ischemia, similar to the clinical situation of myocardial ischemia at the time of revascularization. Methods and Results Swine underwent left anterior descending occlusion (30 minutes), followed by 120 minutes global ischemia protected with hyperkalemic cardioplegia±diazoxide (N=6 each), every 20 minutes cardioplegia, then 60 minutes reperfusion. Cardiac output, time to wean from cardiopulmonary bypass, left ventricular (LV) function, caspase-3, and infarct size were compared. Six animals in the diazoxide group separated from bypass by 30 minutes, whereas only 4 animals in the cardioplegia group separated. Diazoxide was associated with shorter but not significant time to wean from bypass (17.5 versus 27.0 minutes; P=0.13), higher, but not significant, cardiac output during reperfusion (2.9 versus 1.5 L/min at 30 minutes; P=0.05), and significantly higher left ventricular ejection fraction at 30 minutes (42.5 versus 15.8%; P<0.01). Linear mixed regression modeling demonstrated greater left ventricular developed pressure (P<0.01) and maximum change in ventricular pressure during isovolumetric contraction (P<0.01) in the diazoxide group at 30 minutes of reperfusion. Conclusions Diazoxide reduces myocardial stunning and facilitates separation from cardiopulmonary bypass in a model that mimics the clinical setting of ongoing myocardial ischemia before revascularization. Diazoxide has the potential to reduce myocardial stunning in the clinical setting.

Diagnostic Point-of-Care Ultrasound: Recommendations From an Expert Panel.

Diagnostic point-of-care ultrasound (PoCUS) has emerged as a powerful tool to help anesthesiologists guide patient care in both the perioperative setting and the subspecialty arenas. Although anesthesiologists can turn to guideline statements pertaining to other aspects of ultrasound use, to date there remains little in the way of published guidance regarding diagnostic PoCUS. To this end, in 2018, the American Society of Anesthesiologists chartered an ad hoc committee consisting of 23 American Society of Anesthesiologists members to provide recommendations on this topic. The ad hoc committee convened and developed a committee work product. This work product was updated in 2021 by an expert panel of the ad hoc committee to produce the document presented herein. The document, which represents the consensus opinion of a group of practicing anesthesiologists with established expertise in diagnostic ultrasound, addresses the following issues: (1) affirms the practice of diagnostic PoCUS by adequately trained anesthesiologists, (2) identifies the scope of practice of diagnostic PoCUS relevant to anesthesiologists, (3) suggests the minimum level of training needed to achieve competence, (4) provides recommendations for how diagnostic PoCUS can be used safely and ethically, and (5) provides broad guidance about diagnostic ultrasound billing.

Transcatheter Aortic Valve Replacements: Current Trends and Future Directions.

Since the 1960s when the first aortic surgical aortic valve replacement (SAVR) was performed, continuous growth in the field of valvular technology has occurred. Although SAVR remains a lifesaving procedure, minimally invasive transcatheter aortic valve replacement has revolutionized and expanded aortic valve replacement to patients who were not previously SAVR candidates, increasing their quality of life and survival. Since its introduction in the United States in 2011, the technology and practice have rapidly expanded. Hybrid techniques have been developed that combine surgical access to the vasculature with valvular deployment over transcatheter systems. This literature review aims to describe the differences between the current available valve technologies, review approaches to surgical technique, discuss anesthetic considerations, and look forward to future directions, trends, and challenges.

Noteworthy Literature published in 2017 for Perioperative Echocardiography.

In this inaugural review, we present noteworthy advances in perioperative echocardiography relevant to the cardiac anesthesiologist. These studies come from different clinical realms including advances in mitral valve imaging, perioperative echocardiographic evaluation, and critical care echocardiography. The importance of perioperative echocardiography continues to grow with cardiac anesthesiologists positioned in a critical role throughout the perioperative care continuum.

The Genetic and Molecular Bases for Hypertrophic Cardiomyopathy: The Role for Calcium Sensitization.

Hypertrophic cardiomyopathy (HCM) affects millions of people around the world as one of the most common genetic heart disorders and leads to cardiac ischemia, heart failure, dysfunction of other organ systems, and increased risk for sudden unexpected cardiac deaths. HCM can be caused by single-point mutations, insertion or deletion mutations, or truncation of cardiac myofilament proteins. The molecular mechanism that leads to disease progression and presentation is still poorly understood, despite decades of investigations. However, recent research has made dramatic advances in the understanding of HCM disease development. Studies have shown that increased calcium sensitivity is a universal feature in HCM. At the molecular level, increased crossbridge force (or power) generation resulting in hypercontractility is the prominent feature. Thus, calcium sensitization/hypercontractility is emerging as the primary stimulus for HCM disease development and phenotypic expression. Cross-bridge inhibition has been shown to halt HCM presentation, and myofilament desensitization appears to reduce lethal arrhythmias in animal models of HCM. These advances in basic research will continue to deepen the knowledge of HCM pathogenesis and are beginning to revolutionize the management of HCM.

Defining the Role of Intraoperative Transesophageal Echocardiography During Radical Nephrectomy With Inferior Vena Cava Tumor Thrombectomy for Renal Cell Carcinoma.

OBJECTIVE: To determine the impact of transesophageal echocardiography on the surgical management of patients undergoing nephrectomy and inferior vena cava tumor thrombectomy for renal cell carcinoma. MATERIALS AND METHODS: We retrospectively analyzed intraoperative records of 67 patients with renal cell carcinoma and level II-IV invasion of the inferior vena cava who underwent nephrectomy with tumor thrombectomy between 2007 and 2015. Based on preoperative imaging, patients were categorized according to vena cava thrombus level. Diagnostic utility and impact on surgical management were extracted from the operative note, anesthesia record, and intraoperative echocardiography report. RESULTS: Twelve of 34 patients (35%) with level II thrombus, 14 of 18 (78%) with level III thrombus, and 15 of 15 (100%) with level IV thrombus had intraoperative transesophageal echocardiography. With increasing level of tumor thrombus, the diagnostic yield and surgical impact increased. Echocardiography provided new diagnostic information in 7 of 12 (58%) patients with level II thrombus and altered surgical management in 16%. Among level III thrombus patients, echocardiography provided new diagnostic information in 12 of 14 (86%) and altered surgical management in 21%. Echocardiography provided new diagnostic information and impacted surgical management in all 15 (100%) patients with a level IV thrombus. CONCLUSION: The diagnostic yield of intraoperative transesophageal echocardiography increases in patients with greater vena caval tumor thrombus extension. This information has a significant influence on surgical decision-making.

Intraoperative transesophageal echocardiography and ventricular assist device insertion.

A decade after cardiac surgery was established, transesophageal echocardiography (TEE) was developed and used to evaluate perioperative cardiac performance. It has become an invaluable tool to provide real-time information in the cardiac operating room. TEE provides practical and useful information prior to insertion as well as after placement of the device. Additionally, during episodes of device malfunction or hemodynamic instability, TEE can be extremely useful in defining the etiology of the problem. As ventricular assist devices (VADs) have undergone evolution in design and as more VADs are being implanted, the development of specific indications for TEE use during device placement is a relevant issue. Formal guidelines for use of TEE during VAD insertion are yet to be adopted or implemented, but for now TEE remains an essential tool for managing this patient population.

Threshold for adrenomedullary activation and increased cardiac work during mild core hypothermia.

Postoperative hypothermia increases the incidence of ischaemic cardiac events in patients at risk, but the underlying mechanism is unclear. One possibility is increased cardiac work related to the sympathoneural or adrenomedullary hormonal responses. In awake human volunteers, the present study assessed the effects of mild core hypothermia on these responses, and on the associated changes in indices of cardiac work. A total of 11 healthy men were studied on two separate days. On one day, core temperature (T(c)) was decreased by the intravenous infusion of cold normal saline (4 degrees C; 60 ml/kg over 30 min) through a central venous catheter. On the other day (normothermic control), warm normal saline (37 degrees C; 60 ml/kg over 30 min) was given intravenously. Transthoracic echocardiograms, the sympathoneural response (noradrenaline) and the adrenomedullary response (adrenaline) were evaluated before, during and after the intravenous infusions. Echocardiography was used to measure left ventricular function and cardiac output. Compared with the normothermic control treatment, core cooling of 0.7 degrees C was associated with increased plasma noradrenaline (220% increase; P=0.001), whereas adrenaline, cardiac output, heart rate and the rate-pressure product were unchanged. After core cooling of 1.0 degrees C, increases in noradrenaline (by 230%; P=0.001), adrenaline (by 68%; P=0.05), cardiac output (by 23%; P=0.04), heart rate (by 16%; P=0.04) and rate-pressure product (by 25%; P=0.007) were all significant compared with the normothermic control treatment. In conclusion, there is a T(c) threshold, below which an adrenomedullary (adrenaline) response is triggered in addition to the sympathoneural (noradrenaline) response. This T(c) threshold (approximately 1 degrees C below the normothermic baseline) is also associated with an increase in haemodynamic indices of cardiac work. Mild core hypothermia therefore constitutes a catecholamine-mediated cardiovascular "stress test".