Cardiac thoracic vascular & perfusion (CTVP): Overview

Abstract in English, French
Purpose: Clinicians presume a relationship between the management of blood pressure during cardiac surgery and postoperative morbidity and mortality. With limited evidence to inform practice, we surveyed Canadian cardiac anesthesiologists, perfusionists, and cardiac surgeons. We sought to solicit information to inform a trial evaluating the blood pressure management approach on outcomes after cardiac surgery.

Methods: We iteratively developed a survey assessing the lowest and highest blood pressures respondents would target, the narrowest feasible blood pressure range to achieve, the range of blood pressure observed in clinical practice, and factors influencing targeted blood pressure before, during, and after cardiopulmonary bypass (CPB). We contacted leads from every Canadian hospital providing cardiac surgery to distribute the survey via a computerized link. We used a modified Dillman approach to optimize response rate. Responses were analyzed descriptively.

Results: Of 819 clinicians surveyed, 532 (65%) responded. Respondents' lowest pooled mean arterial pressure (MAP) target, presented as mean (standard deviation [SD]), was 59 (6) mm Hg before CPB, 55 (7) mm Hg during CPB, and 60 (5) mm Hg after CPB. Respondents' highest pooled MAP target, presented as mean (SD), was 92 (10) mm Hg before CPB, 84 (7) mm Hg during CPB, and 75 (6) mm Hg after CPB. The narrowest feasible MAP range, presented as mean (SD), all respondents believed could be achieved was 19 (7) mm Hg before CPB, 16 (7) mm Hg during CPB, and 20 (7) mm Hg after CPB.

Conclusions: The responses to our survey support the clinical acceptability of a trial examining blood pressure target thresholds at the extreme ends of the range recommended by existing guidelines and the feasibility of maintaining blood pressure within a narrow target range.

Abstract
Thoracic paravertebral block (TPVB) is recommended by the Procedure Specific Postoperative Pain Management (PROSPECT) working group for video-assisted thoracoscopic surgery (VATS). Although perineural magnesium and dextran have been used to prolong block duration, combined use is not reported in the literature. In this case report, the author combined dextran and magnesium with levobupivacaine in TPVB as part of multimodal analgesia for a patient with recurrent lung cancer undergoing VATS, which resulted in satisfactory pain control and sensory blockade up to 3 days postoperatively. Nonetheless, the findings of this study are at most exploratory and call for further research to prove the efficacy and safety of this combination.

Abstract
Introduction: Cardiac surgery is frequently associated with vasoplegia and vasopressor treatment. Both may be associated with postoperative complications and prolonged length of stay. The most frequently used vasopressor is norepinephrine. However, in a pilot, double-blind, randomised controlled trial (RCT) in cardiac surgery patients, angiotensin II was effective in maintaining blood pressure and was associated with a shorter duration of hospital stay than norepinephrine. Furthermore, hyperreninaemic patients were more sensitive to angiotensin II. These findings support the need for a larger RCT to determine whether angiotensin II is superior to norepinephrine as a first-line treatment for low blood pressure after cardiac surgery.

Methods and analysis: We will conduct a double-blind RCT comparing an infusion of either angiotensin II or norepinephrine intraoperatively and for up to 48 hours after the start of surgery. We will randomly allocate 400 cardiac surgery patients at multiple centres in two countries to either an equipotent angiotensin II or norepinephrine infusion, titrated to a mean arterial pressure of 70-80 mm Hg. The primary outcome will be length of hospital stay. Secondary outcomes will include a composite of renal, cardiovascular and neurological events. A subgroup analysis of patients with elevated baseline renin levels will be undertaken.

Ethics and dissemination: Ethical approval has been granted by the Alfred Human Research Ethics Committee on 14 July 2023 (HREC/97814/Alfred-2023). Results will be published on completion of the trial.

Trial registration number: Australian and New Zealand Clinical Trials Registry: ACTRN12623000848606.

Abstract
Background: Transplantation of livers obtained from donors after circulatory death is associated with an increased risk of nonanastomotic biliary strictures. Hypothermic oxygenated machine perfusion of livers may reduce the incidence of biliary complications, but data from prospective, controlled studies are limited.

Methods: In this multicenter, controlled trial, we randomly assigned patients who were undergoing transplantation of a liver obtained from a donor after circulatory death to receive that liver either after hypothermic oxygenated machine perfusion (machine-perfusion group) or after conventional static cold storage alone (control group). The primary end point was the incidence of nonanastomotic biliary strictures within 6 months after transplantation. Secondary end points included other graft-related and general complications.

Results: A total of 160 patients were enrolled, of whom 78 received a machine-perfused liver and 78 received a liver after static cold storage only (4 patients did not receive a liver in this trial). Nonanastomotic biliary strictures occurred in 6% of the patients in the machine-perfusion group and in 18% of those in the control group (risk ratio, 0.36; 95% confidence interval [CI], 0.14 to 0.94; P = 0.03). Postreperfusion syndrome occurred in 12% of the recipients of a machine-perfused liver and in 27% of those in the control group (risk ratio, 0.43; 95% CI, 0.20 to 0.91). Early allograft dysfunction occurred in 26% of the machine-perfused livers, as compared with 40% of control livers (risk ratio, 0.61; 95% CI, 0.39 to 0.96). The cumulative number of treatments for nonanastomotic biliary strictures was lower by a factor of almost 4 after machine perfusion, as compared with control. The incidence of adverse events was similar in the two groups.

Conclusions: Hypothermic oxygenated machine perfusion led to a lower risk of nonanastomotic biliary strictures following the transplantation of livers obtained from donors after circulatory death than conventional static cold storage. (Funded by Fonds NutsOhra; DHOPE-DCD ClinicalTrials.gov number, NCT02584283.).

Abstract
Despite improvements in surgical techniques and perioperative care, cardiac surgery still is burdened by relatively high mortality and frequent major postoperative complications, including myocardial dysfunction, pulmonary complications, neurologic injury, and acute kidney injury. Although the surgeon's skills and volume and patient- and procedure-related risk factors play a major role in the success of cardiac surgery, there is growing evidence that also optimizing perioperative care may improve outcomes significantly. The present review focuses on the aspects of perioperative care that are strictly related to the anesthesia regimen, with special reference to volatile anesthetics and neuraxial anesthesia, whose effect on outcome in adult cardiac surgery has been investigated extensively.

Key points:
• The rate of fluid accumulation relative to pericardial stretch and the presence or absence of compensatory mechanisms are crucial in the development of cardiac tamponade.
• The pathophysiology of tamponade entails exaggerated variations in the normal haemodynamic changes that occur during respiration.
• Echocardiography is key to the diagnosis of pericardial effusions and tamponade.
• The primary goal in the management of tamponade is to relieve the effect of the fluid or clot on cardiac pressures and restore forward flow.
• Perioperative goals are to maintain preload and systemic vascular resistance; and to avoid bradycardia and myocardial depression.

The ISCHEMIA trial randomised over 5000 patients with moderate to severe stable coronary artery disease to compare initial invasive therapy with conservative medical treatment. The was a trend to a higher event rate in the invasive group at 6 months and a lower event rate in the invasive group at 5 years however overall the trial did not find any significant difference between the groups.

Early aortic valve replacement versus conservative care was compared in a randomised trial of 145 asymptomatic, very severe aortic stenosis patients. This study found significant and dramatic reduction in mortality in the early surgery compared to the conservative care group.

Koponen et al review the Vasoactive-Inotropic Score (VIS) as a tool to predict risk of mortality and morbidity after cardiac surgery and demonstrate the validity as an independent predictor for adults up to 1 year post cardiac surgery.

Khoche et al have published the fourth in a series of annual review articles on perioperative echocardiography “selected highlights from 2019”. This article reviews recent advances in echo topics such as quantification of RV function and RV diastolic function, the latest on Aortic Valve stenosis severity in the operating room, 3D echo of the tricuspid valve and more.