The cervical branch-first technique in complex resternotomy

Background

Branch-first total aortic arch repair is a paradigm shift in the technical approach for uninterrupted neuroprotection during open aortic surgery. This technique is further modified to instigate hazardous sternal reentry in patients with hostile mediastinal anatomy at risk of aortic injury.

Methods

Intraoperative preparation and the illustrated operative technique of the cervical branch-first technique are described. The accompanying case series narrates the experiences and outcomes of 4 patients who underwent successful complex reoperative aortic surgery utilizing this technique.

Results

The indications for resternotomy included a sixth reoperation for recurrent mycotic aortic pseudoaneurysm, a third reoperation for extensive infective endocarditis, a reoperation for complete Bentall graft dehiscence with contained aortic rupture, and a third reoperation for residual type A dissection. All patients survived their proposed surgery. Two patients were operated on in an emergency setting. Two patients separated from cardiopulmonary bypass with extracorporeal support. None experienced permanent neurological sequelae, gut ischemia, peripheral arterial complications, or in-hospital mortality. One mortality due to decompensated heart failure was reported at 6 months postoperatively.

Conclusions

The cervical branch-first technique offers unparalleled advantage in neuroprotection from an early stage of complex reoperative aortic surgery. It provides an independent circuit for complete antegrade cerebral perfusion, irrespective of suspension to circulatory flows to the rest of the body during complex reentry into hostile chests. Our experience to date has demonstrated promising outcomes and further refinements will guide patient selection best suited for this technique.

Valve-sparing aortic root replacement: Long-term variables significantly associated with mortality and morbidity

OBJECTIVES

In aortic root surgery, valve-sparing aortic root replacement is an attractive alternative by mitigating the risks inherent to prosthetic valves; however, little is known about the variables that impact its durability. We review our mid- to long-term outcomes after valve-sparing aortic root replacement and describe factors that impact survival and valve reintervention and insufficiency.

METHODS

A retrospective review of 284 consecutive patients undergoing valve-sparing aortic root replacement between November 1999 and January 2022 at Austin Health, Melbourne, Australia, was undertaken, with a median follow-up of 6.43 ± 4.83 years, but up to 22.0 years. Freedom from mortality, aortic reintervention, and insufficiency was analyzed using Kaplan-Meier methods, Cox proportional hazard models, and Fine-Gray analysis.

RESULTS

The median age of patients at intervention was 60.0 years (interquartile range, 48.0-67.0), of whom 68 (23.9%) had bicuspid aortic valve disease, 27 (9.5%) had Marfan syndrome, 119 (41.9%) had severe aortic root dilation (>50 mm), and 155 had (54.6%) severe aortic insufficiency at the time of intervention. The 30-day mortality was 1.8%, with freedom from mortality of 96.0% (95% CI, 92.6-97.8) at 5 years and 88.2% (95% CI, 81.4-92.6) at 10 years. Freedom from aortic reintervention was 92.2% (95% CI, 87.7-95.2) at 5 years and 79.8% (95% CI, 71.8-85.8) at 10 years. Factors associated with reintervention were concomitant leaflet repair (hazard ratio, 8.13, 95% CI, 1.07-61.7) and bicuspid valvulopathy (hazard ratio, 2.23, 95% CI, 1.07-4.68), with reintervention in the bicuspid aortic valve being more likely due to aortic stenosis and in the tricuspid aortic valve due to aortic insufficiency (chi-square P = .05). The freedom from aortic insufficiency was 89.1% (95% CI, 83.5-92.9), 84.9% (95% CI, 77.8-89.9) at 5 and 10 years, respectively, and 80.7% (95% CI, 71.0-87.4).

CONCLUSIONS

Valve-sparing aortic root replacement has excellent long-term outcomes, with low mortality and reintervention rates. Concomitant leaflet repair and bicuspid valve disease are the only long-term factors associated with reintervention.

Branch-first Continuous Perfusion Aortic Arch Replacement: Midterm Results

BACKGROUND

Aortic arch surgery necessitates interruption of perfusion, thus conferring higher morbidity and mortality compared with other aortic surgery. This report describes a branch-first continuous perfusion aortic arch replacement (BF-CPAR) technique that overcomes these shortcomings and describes midterm results with this technique.

METHODS

This report represents the corresponding author's 15-year experience with BF-CPAR, which involves preliminary mobilization and branch reconstruction before circulatory arrest by using a modified trifurcation graft. Demographic, procedural, and outcome (mortality, reintervention, morbidity, and stroke) were analyzed with Kaplan-Meier and Cox regression.

RESULTS

Over 15 years (July 2005-February 2021), 155 patients underwent BF-CPAR, at a median age of 66.8 years, 106 (68.3%) on an elective basis and 49 (31.6%) on an emergency basis. There were no aortic deaths after the first postoperative year, thereby resulting in a 1- and 10-year freedom from aortic death constant at 95.6% in patients undergoing elective BF-CPAR and 93.3% in patients undergoing emergency BF-CPAR patients, respectively. Freedom from reintervention on the operated segment at 5 and 9 years was 93.2% and 93.2% in patients undergoing elective cases and 97.1% and 91.4% in emergency cases, respectively. The 10-year freedom from any aortic reintervention was 72.8% in elective patients and 29.2% in emergency patients; there were 38 reinterventions, 76.3% (n = 29/38) done for progression of aneurysmal or dissection disease, of which 79.3% (n = 23/29) were completed endovascularly. Freedom from cerebrovascular-related events at 5 and 10 years was 90.3% and 82.6% in patients undergoing elective BF-CPAR and 75.4% for both time points in patients undergoing emergency BF-CPAR, respectively.

CONCLUSIONS

BF-CPAR has excellent 10-year results for elective and emergency cases of arch replacement.

Modern Cardiac Surgical Outcomes in Nonagenarians: A Multicentre Retrospective Observational Study

Background

There have been multiple recent advancements in the selection, optimisation and management of patients undergoing cardiac surgery. However, there is limited data regarding the outcomes in nonagenarians, despite this cohort being increasingly referred for these interventions. The objective of this study was to describe the patient characteristics, management and outcomes of a cohort of nonagenarians undergoing cardiac surgery receiving contemporary peri-operative care.

Methods

After receiving ethics approval, we conducted a retrospective observational study of nonagenarians who had undergone cardiac surgery requiring a classic median sternotomy. All operative indications were included. We excluded patients who underwent transcatheter aortic valve implantation (TAVI), and surgery on the thoracic aorta via an endovascular approach (TEVAR). Patients undergoing TEVAR often have the procedure done under sedation and regional blocks with local anesthetic solution. There is no open incision and these patients do not require cardiopulmonary bypass. We also excluded patients undergoing minimally invasive mitral valve surgery via a videoscope assisted approach. These patients do not have a median sternotomy, have the procedure done via erector spinae block, and often are extubated on table. Data were collected from four hospitals in Victoria, Australia, over an 8-year period (January 2012–December 2019). The primary objective was to assess 6-month mortality in nonagenarian patients undergoing cardiac surgery and to provide a detailed overview of postoperative complications. We hypothesized that cardiac surgery in nonagenarian patients would be associated with a 6-month postoperative mortality <10%. As a secondary outcome, we hypothesized that significant postoperative complications (i.e., Clavien Dindo Grade IIIb or greater) would occur in > 30% of patients.

Results

A total of 12,358 adult cardiac surgery patients underwent surgery during the study period, of whom 18 nonagenarians (0.15%) fulfilled inclusion criteria. The median (IQR) [min-max] age was 91.0 years (90.0:91.8) [90–94] and the median body mass index was 25.0 (kg/m²) (22.3:27.0). Comorbidities, polypharmacy, and frailty were common. The median predicted mortality as per EuroSCORE-II was 6.1% (4.1:14.5). There were no cases of intra-operative, in-hospital, or 6-month mortality. One (5.6%) patient experienced two Grade IIIa complications. Three (16.7%) patients experienced Grade IIIb complications. Three (16.7%) patients had an unplanned hospital readmission within 30 days of discharge. The median value for postoperative length of stay was 11.6 days (9.8:17.6). One patient was discharged home and all others were discharged to an inpatient rehabilitation facility.

Conclusion

In this selected, contemporary cohort of nonagenarian patients undergoing cardiac surgery, postoperative 6-month mortality was zero. These findings support carefully selected nonagenarian patients being offered cardiac surgery (Trials Registry: https://www.anzctr.org.au/ACTRN12622000058774.aspx).

Branch-first continuous perfusion aortic arch replacement: insight into our results

BACKGROUND

Aortic-arch surgery often necessitates interruption of perfusion conferring higher morbidity and mortality compared to other aortic segments. We describe our Branch-first continuous-perfusion aortic-arch replacement (BF-CPAR) technique which overcomes these shortcomings, describing technique, results and improved outcomes.

METHODS

This represents the senior author's 15-year experience with BF-CPAR. Description of demographics, procedures and outcomes have been stratified by dissection and aneurysm etiology, with prediction of mortality, cerebrovascular events, renal failure, and end-organ ischemia undertaken using multivariable logistic regression analysis.

RESULTS

From July 2005 to February 2021, 155 patients underwent BF-CPAR, 93 for aneurysms and 62 for dissections. Median age at intervention was 66.8 years, 96 (61.9%) male, 18 (11.6%) with history of previous dissection repair, and 49 (31.6%) on an emergent basis. We observed an overall mortality of 4.5% (N.=7) and stroke of 3.2% (N.=5). Comparing elective to urgent cases, the mortality and stroke rates were significantly lower at 0.0% and 1.9% versus 14.2% and 6.1% (risk differences: 14.3% and 2.3%, P<0.01) respectively. Predictors of mortality were age (1.11 per year, 95% CI: 1.00-1.23, P=0.05); of stroke were hypercholesterolemia (14.4, 1.84-111.9, P=0.01) and hypertension (0.07, 0.01-0.84, P<0.01); and of dialysis were dissection (6.60, 1.76-24.7, P<0.01).

CONCLUSIONS

BF-CPAR is safe and adds to the armamentarium of aortic arch repair. In elective and uncomplicated acute-dissection cases, it has no mortality and low stroke (1.9%), and vital organ dysfunction risk. Its results which are comparable to many of the best currently reported series, is driven by avoidance of cerebral circulatory arrest and reduction of cardiac and visceral ischemic time.

STABILISE; treatment of aortic dissection, a single Centre experience

Purpose

To outline the process of the STABILISE technique and its use; reporting patient outcomes and midterm follow up for complicated aortic dissection.

Materials and methods

Single centre retrospective analysis from January 2011 to January 2021 using the STABILISE technique which utilises balloon assistance to facilitate intimal disruption and promote aortic relamination.

Results

Sixteen patients underwent endovascular aortic repair with the STABILISE technique for aortic dissection over the study period. Fourteen patients (14/16; 88%) had acute dissection. Two of 16 (12%) were chronic. The median age of the patient cohort was 61 years (range 32–80 years) and consisted of a male majority (n = 11; 69%). The median time from diagnosis to intervention was 5 days (1–115 days; IQR 1–17.3). More than half (56%) had surgical repair of a acute type A aortic dissection prior to radiological intervention. The procedure was technically successful with no procedural mortality. Two patients were lost to follow up and two died in the post-operative period. Twelve patients had ongoing follow up with an average number of 2.9 ± 1.6 scans performed. Follow up was available in thirteen patients (81%) with a median follow up period of 1097 days (IQR 707–1657). The rate of re-intervention (n = 2/16; 13%) requiring additional stenting was in line with published re-intervention data (15%). Follow up showed a reduction in false lumen size following treatment with total luminal dimensions remaining stable over the follow-up period.

Conclusion

The STABILISE technique as a procedure for complicated aortic dissection, either acute or chronic, appears safe with stable mid-term aortic remodelling and patient outcomes.

Level of evidence

Level 3, Retrospective cohort study.

“Branch-First total arch replacement”: a valuable alternative to frozen elephant trunk in acute type A aortic dissection?

The "Branch-First total arch replacement" technique has been used extensively in both elective and acute situations, including in type A aortic dissection. The focus of the Branch-First technique is to reduce the risk of neurological and end-organ dysfunction associated with arch replacement by optimising neuroprotection, distal organ perfusion and myocardial protection. The Branch-First technique is a valuable alternative to the frozen elephant trunk (FET) technique in type A aortic dissection, providing a stable landing zone for subsequent interventions on the distal aorta should they be required. Combining the Branch-First technique with FET in appropriate cases can further improve outcomes. We discuss the merits of the Branch-First technique, and contrast them to those of FET techniques for repair of type A aortic dissection.

Paving the way for E-vita open NEO hybrid prosthesis implantation for complex aortic arch disease in Asia-Pacific

We report first in man implantations of the newly designed Evita-open-NEO hybrid prosthesis for complex aortic arch disease from three different countries in Asia-Pacific including instructions on how to proceed with perioperative coagulation management.

Fast-track recovery program after cardiac surgery in a teaching hospital: a quality improvement initiative

Objective

Fast-track cardiac anesthesia (FTCA) is a technique that may improve patient access to surgery and maximize workforce utilization. However, feasibility and factors impacting FTCA implementation remain poorly explored both locally and internationally. We describe the specific intraoperative and postoperative protocols for our FTCA program, assess protocol compliance and identify reasons for FTCA failure.

Results

We tested the program in 16 patients undergoing elective cardiac surgery requiring cardiopulmonary bypass. There was 100% compliance with the FTCA protocols. Four (25%) patients successfully completed the FTCA protocol (extubated < 4 h postoperatively and discharged from the intensive care unit on the same operative day).

COVID-19: An Australian center's perspective

SARS CoV-2 (COVID 19) is having a deep and lasting impact around the world. We review the effect it has had on our cardiothoracic surgery practice in Australia and give insights into our contingency planning, restructuring, practice changes, and the effect on our patients in this evolving pandemic.

Long-Term Results of the RAPCO Trials

Background:

An internal thoracic artery graft to the left anterior descending artery is standard in coronary bypass surgery, but controversy exists on the best second conduit. The RAPCO trials (Radial Artery Patency and Clinical Outcomes) were designed to compare the long-term patency of the radial artery (RA) with that of the right internal thoracic artery (RITA) and the saphenous vein (SV).

Methods:

In RAPCO-RITA (the RITA versus RA arm of the RAPCO trial), 394 patients <70 years of age (or <60 years of age if they had diabetes mellitus) were randomized to receive RA or free RITA graft on the second most important coronary target. In RAPCO-SV (the SV versus RA arm of the RAPCO trial), 225 patients ≥70 years of age (or ≥60 years of age if they had diabetes mellitus) were randomized to receive RA or SV graft. The primary outcome was 10-year graft failure. Long-term mortality was a nonpowered coprimary end point. The main analysis was by intention to treat.

Results:

In the RA versus RITA comparison, the estimated 10-year patency was 89% for RA versus 80% for free RITA (hazard ratio for graft failure, 0.45 [95% CI, 0.23–0.88]). Ten-year patient survival estimate was 90.9% in the RA arm versus 83.7% in the RITA arm (hazard ratio for mortality, 0.53 [95% CI, 0.30–0.95]). In the RA versus SV comparison, the estimated 10-year patency was 85% for the RA versus 71% for the SV (hazard ratio for graft failure, 0.40 [95% CI, 0.15–1.00]), and 10-year patient survival estimate was 72.6% for the RA group versus 65.2% for the SV group (hazard ratio for mortality, 0.76 [95% CI, 0.47–1.22]).

Conclusions:

The 10-year patency rate of the RA is significantly higher than that of the free RITA and better than that of the SV.

Registration:

URL: https://www.clinicaltrials.gov ; Unique identifier: NCT00475488.

Trends and controversies in type A aortic surgery in the 21st century: Branch first aortic arch replacement

BACKGROUND

Acute type A dissection (ATAAD) remains a morbid condition with reported surgical mortality as high as 26%.

AIMS

We describe our surgical approach to ATAAD using a "branch first" total arch replacement technique which avoids a traditional approach of ascending aorta and "hemi-arch" replacement utilising deep hypothermic circulatory arrest (DHCA) and an open distal anastomosis. We also discuss the indications for adjunct techniques such as the frozen elephant trunk or complete aortic repair with endovascular methods.

MATERIALS & METHODS

Thirty-nine patients underwent a "branch first" total aortic arch replacement for ATAAD.

RESULTS

We had an overall 5(12.8%) hospital mortalities and 2 (5.1%) strokes. There were no deaths or strokes in patients without pre-operative organ malperfusion or shock.

DISCUSSION

Arch replacement using the "branch-first technique" allows for complete proximal aortic replacement and sets up for straightforward future distal aortic intervention.

CONCLUSION

The use of a branch first aortic arch replacement technique in ATAAD results in improved outcomes and is an approach applicable to all cardiac surgeons not only the aortic sub specialist.

Technique and rationale for branch-first total aortic arch repair

Objective

Our objective was to describe the technique and rationale for branch-first total aortic arch repair.

Methods

Branch-first total aortic arch repair involves serial clamping, reconstruction, and reperfusion of each of the arch branches using a specially designed trifurcation graft with a side port. During this sequence, perfusion to the heart and distal organs are preserved and continuous antegrade cerebral perfusion is permitted via the trifurcation graft. The diseased aorta is excised and replaced with a Dacron graft (W.L. Gore and Associates, Newark, Del) with a perfusion side port. The trifurcation graft is anastomosed to the new proximal ascending aorta.

Results

The branch-first technique permits total aortic arch repair without global cerebral circulatory arrest and excessive hypothermia. It shortens distal organ and cardiac ischemic time, and reduces the opportunity for air and particulate embolization during aortic repair.

Conclusions

Branch-first total aortic arch repair allows continuous antegrade cerebral perfusion and shortens distal organ and cardiac ischemic time, with unobstructed access to the full extent of the diseased aortic arch.

Continuous Magnesium Infusion to Prevent Atrial Fibrillation After Cardiac Surgery: A Sequential Matched Case-Controlled Pilot Study

OBJECTIVE

The authors aimed to test whether a bolus of magnesium followed by continuous intravenous infusion might prevent the development of atrial fibrillation (AF) after cardiac surgery.

DESIGN

Sequential, matched, case-controlled pilot study.

SETTING

Tertiary university hospital.

PARTICIPANTS

Matched cohort of 99 patients before and intervention cohort of 99 consecutive patients after the introduction of a continuous magnesium infusion protocol.

INTERVENTIONS

The magnesium infusion protocol consisted of a 10 mmol loading dose of magnesium sulphate followed by a continuous infusion of 3 mmol/h over a maximum duration of 96 hours or until intensive care unit discharge.

MEASUREMENTS AND MAIN RESULTS

The study groups were balanced except for a lower cardiac index in the intervention cohort. The mean duration of magnesium infusion was 27.93 hours (95% confidence interval [CI]: 24.10-31.76 hours). The intervention group had greater serum peak magnesium levels: 1.72 mmol/L ± 0.34 on day 1, 1.32 ± 0.36 on day 2 versus 1.01 ± 1.14 and 0.97 ± 0.13, respectively, in the control group (p < 0.01). Atrial fibrillation occurred in 25 patients (25.3%) in the intervention group and 40 patients (40.4%) in the control group (odds ratio 0.49, 95% CI, 0.27-0.92; p = 0.023). On a multivariate Cox proportional hazards model, the hazard ratio for the development of AF was significantly less in the intervention group (hazard ratio 0.45, 95% CI, 0.26-0.77; p = 0.004).

CONCLUSION

The magnesium delivery strategy was associated with a decreased incidence of postoperative AF in cardiac surgery patients. These findings provide a rationale and preliminary data for the design of future randomized controlled trials.

Current status in decision making to treat acute type A dissection: limited versus extended repair

Acute type A aortic dissection remains one of the most challenging conditions in aortic surgery. Despite the advancements in the field, the mortality rate still remains high. Though there is a general consensus that the ascending aorta should be replaced, the distal extension of the surgery still remains a controversy. Few surgeons argue for a conservative approach to reduce operative and postoperative morbidity while others considering the problems associated with "downstream problems" support an aggressive approach including a frozen elephant trunk. The cohort in the Indian subcontinent and APAC is far different from the western world. Many factors determine the decision for surgery apart from the pathology of the disease. Economy, availability of the suitable prosthesis, the experience of the surgeon, ease of access to the medical facility all contribute to the decision making to treat acute type A dissection.

Plasma ACE2 Activity Predicts Mortality in Aortic Stenosis and Is Associated With Severe Myocardial Fibrosis

OBJECTIVES

This study investigated the relationship between plasma angiotensin-converting enzyme 2 (ACE2) activity levels and the severity of stenosis and myocardial remodeling in patients with aortic stenosis (AS) and determined if plasma ACE2 levels offered incremental prognostic usefulness to predict all-cause mortality.

BACKGROUND

ACE2 is an integral membrane protein that degrades angiotensin II and has an emerging role as a circulating biomarker of cardiovascular disease.

METHODS

Plasma ACE2 activity was measured in 127 patients with AS; a subgroup had myocardial tissue collected at the time of aortic valve replacement.

RESULTS

The median plasma ACE2 activity was 34.0 pmol/ml/min, and levels correlated with increased valvular calcification (p = 0.023) and the left ventricular (LV) mass index (r = 0.34; p < 0.001). Patients with above-median plasma ACE2 had higher LV end-diastolic volume (57 ml/m² vs. 48 ml/m²; p = 0.021). Over a median follow-up of 5 years, elevated plasma ACE2 activity was an independent predictor of all-cause mortality after adjustment for relevant clinical, imaging, and biochemical parameters (HR: 2.28; 95% CI: 1.03 to 5.06; p = 0.042), including brain natriuretic peptide activation (integrated discrimination improvement: 0.08; p < 0.001). In 22 patients with plasma and tissue, increased circulating ACE2 was associated with reduced myocardial ACE2 gene expression (0.7-fold; p = 0.033) and severe myocardial fibrosis (p = 0.027).

CONCLUSIONS

In patients with AS, elevated plasma ACE2 was a marker of myocardial structural abnormalities and an independent predictor of mortality with incremental value over traditional prognostic markers. Loss of ACE2 from the myocardium was associated with increased fibrosis and higher circulating ACE2 levels.

Conservative versus conventional oxygen therapy for cardiac surgical patients: A before-and-after study

Avoiding hypoxaemia is considered crucial in cardiac surgery patients admitted to the intensive care unit (ICU). However, avoiding hyperoxaemia may also be important. A conservative approach to oxygen therapy may reduce exposure to hyperoxaemia without increasing the risk of hypoxaemia. Using a before-and-after design, we evaluated the introduction of conservative oxygen therapy (target SpO₂ 88%-92% using the lowest FiO₂) for cardiac surgical patients admitted to the ICU. We studied 9041 arterial blood gas (ABG) datasets: 4298 ABGs from 245 'conventional' and 4743 ABGs from 298 'conservative' oxygen therapy patients. During mechanical ventilation (MV) and while in the ICU, compared to the conventional group, conservative group patients had significantly lower FiO₂ exposure and PaO₂ values ( P < 0.001 for each). Accordingly, using the mean PaO₂ during MV, more conservative group patients were classified as normoxaemic (226 versus 62 patients, P < 0.01), fewer as hyperoxaemic (66 versus 178 patients, P < 0.01) and no patient in either group as hypoxaemic or severely hypoxaemic. Moreover, more ABG samples were hyperoxaemic or severely hyperoxaemic during conventional treatment ( P < 0.001). Finally, there was no difference in ICU or hospital length of stay, ICU or hospital mortality or 30-day mortality between the groups. Our findings support the feasibility and physiological safety of conservative oxygen therapy in patients admitted to ICU after cardiac surgery.

A Pilot Randomized Controlled Study of Mild Hypercapnia During Cardiac Surgery With Cardiopulmonary Bypass

OBJECTIVES

To test whether targeted therapeutic mild hypercapnia (TTMH) would attenuate cerebral oxygen desaturation detected using near-infrared spectroscopy during cardiac surgery requiring cardiopulmonary bypass (CPB).

DESIGN

Randomized controlled trials.

SETTING

Operating rooms and intensive care unit of tertiary hospital.

PARTICIPANTS

The study comprised 30 patients undergoing cardiac surgery with CPB.

INTERVENTIONS

Patients were randomly assigned to receive either standard carbon dioxide management (normocapnia) or TTMH (target arterial carbon dioxide partial pressure between 50 and 55 mmHg) throughout the intraoperative period and postoperatively until the onset of spontaneous ventilation.

MEASUREMENTS AND MAIN RESULTS

Relevant biochemical and hemodynamic variables were measured, and cerebral tissue oxygen saturation (SctO₂) was monitored with near-infrared spectroscopy. Patients were followed-up with neuropsychological testing. Patient demographics between groups were compared using the Fisher exact and Mann-Whitney tests, and SctO₂ between groups was compared using repeated measures analysis of variance. The median patient age was 67 years (interquartile range [IQR] 62-72 y), and the median EuroSCORE II was 1.1. The median CPB time was 106 minutes. The mean intraoperative arterial carbon dioxide partial pressure for each patient was significantly higher with TTMH (52.1 mmHg [IQR 49.9-53.9 mmHg] v 40.8 mmHg [IQR 38.7-41.7 mmHg]; p < 0.001) as was pulmonary artery pressure (23.9 mmHg [IQR 22.4-25.3 mmHg] v 18.5 mmHg [IQR 14.8-20.7 mmHg]; p = 0.004). There was no difference in mean percentage change in SctO₂ during CPB in the control group for both hemispheres (left: -6.7% v -2.3%; p = 0.110; right: -7.9% v -1.0%; p = 0.120). Compliance with neuropsychological test protocols was poor. However, the proportion of patients with drops in test score >20% was similar between groups in all tests.

CONCLUSIONS

TTMH did not increase SctO₂ appreciably during CPB but increased pulmonary artery pressures before and after CPB. These findings do not support further investigation of TTMH as a means of improving SctO₂ during and after cardiac surgery requiring CPB.

Permanent pacing and conduction recovery in patients undergoing cardiac surgery for active infective endocarditis in an Australian Tertiary Center

BACKGROUND

Postoperative heart block is common among patients undergoing surgery for infective endocarditis (IE). Limited data exists allowing cardiologists to predict who will require permanent pacemaker (PPM) implantation postoperatively. We aimed to determine the rate of postoperative PPM insertion, predictors for postoperative PPM, and describe PPM utilization and rates of device-related infection during follow-up.

MATERIALS AND METHODS

A retrospective analysis was performed of 191 consecutive patients from a single institution who underwent cardiac surgery for IE between 2001 and 2017. Preoperative and operative predictors for postoperative PPM were evaluated using univariate and multivariate logistic regression.

RESULTS

The rate of postoperative PPM implantation was 11% (17/154). The PPM group had more preoperative prolonged PR interval alone (33% vs 12%; P = .03), coexistent prolonged PR and QRS durations (13% vs 2%; P = .01), infection beyond the valve leaflets (82% vs 41%; P = .001), aortic root debridement (65% vs 23%; P = <.001), patch repair (47% vs 20%; P = .01), postoperative prolonged PR interval (50% vs 24%; P = .01), and prolonged QRS duration (47% vs 15%; P = .001). On multivariate analysis, infection beyond the valve leaflets emerged as an independent predictor for postoperative PPM (odds ratio, 1.94, 95% confidence interval, 1.14-3.28; P = .014). A reduction in PPM utilization was observed in five patients while eight patients continued to show significant ventricular pacing with no underlying rhythm at 12 months. There were no device-related infections.

CONCLUSION

Postoperative PPM was required in 11% of patients undergoing surgery for IE over a 16-year period. Infection beyond the valve leaflet was an independent predictor for postoperative PPM insertion.

Thoracoabdominal Aortic Aneurysm - The Branch First Technique

Surgical management of thoracoabdominal aortic aneurysms is complex. In particular, maintaining adequate spinal cord and reno-visceral protection during the operation can be challenging. We describe here a branch-first technique developed at our institution, endeavoring to minimized renal and visceral organ ischemic time, decrease risk of spinal cord injury, and provide a controlled and uncluttered field in which the surgeon can operate.

Magnesium sulfate therapy after cardiac surgery: a before-and-after study comparing strategies involving bolus and continuous infusion

BACKGROUND

Magnesium therapy may reduce the risk of atrial fibrillation after cardiac surgery. However, studies are heterogeneous in relation to dosage and method of delivery and no studies have directly compared the biochemical effect of different delivery strategies.

AIMS

We conducted a before-and-after study to compare the effects of two strategies of magnesium delivery after cardiac surgery.

METHODS

We conducted a prospective interventional before-and-after study. We enrolled patients admitted to the intensive care unit (ICU) after cardiac surgery and with no history of renal failure. The before period consisted of a single 20 mmol of magnesium sulfate bolus administered over one hour. The after period comprised a 10 mmol magnesium loading dose over one hour followed by a continuous infusion at 3 mmol/h for 12 hours. We measured serum and urine magnesium levels at baseline (T0), at the end of loading dose (T1), 6 (T2) and 12 hours after the intervention (T3).

RESULTS

We enrolled 60 patients (30 in each group) with similar baseline characteristics. In the before period, patients had a higher peak serum magnesium level at T1 (1.88 ± 0.06 v 1.59 ± 0.04 mmo/L; P < 0.001) compared with the after period. However, at 6 hours, patients in the after period had a significantly higher magnesium level (1.61 ± 0.04 v 1.29 ± 0.26 mmol/L; P < 0.001) and this level remained higher at 12 hours (1.70 ± 0.05 v 1.17 ± 0.02; P < 0.001), leading to increased time-weighted magnesaemia (P < 0.001). These changes occurred despite a significantly increased urinary magnesium concentration, fractional excretion of magnesium, and magnesium clearance, which paralleled changes in magnesaemia (P < 0.001).

CONCLUSIONS

The strategy of a 10 mmol magnesium bolus followed by a continuous infusion over 12 hours achieved a more sustained and moderately elevated magnesium concentration in comparison to a single 20 mmol bolus, despite increased urinary losses of magnesium. Further studies are required to assess a more extended continuous infusion.

Total aortic repair for acute type A aortic dissection: a new paradigm

The currently accepted guidelines of open surgical repair for acute type A aortic dissection (ATAAD) include the resection of the primary entry tear, replacement of the ascending aorta and "hemi-arch" with an open distal anastomosis, and aortic valve resuspension and some form of obliteration of the aortic root false lumen. The principal aim being protection against aortic rupture, aortic regurgitation, and coronary ischemia and restoration of antegrade preferential true lumen perfusion. Proponents argue that this operation is tailored to be in the armamentarium of most cardiac surgeons and deliver the lowest early operative risk, while leaving the infrequent long-term sequelae to be dealt with electively by experienced aortic centres. While a superficially compelling argument, the actual outcomes suggest that it falls significantly short of achieving its noble goals on both acute and chronic counts. This led us to develop a seemingly more radical but in practise safe paradigm, which aims to achieve total aortic healing in the acute phase.

The effect of protamine dosing variation on bleeding and transfusion after heparinisation for cardiopulmonary bypass

INTRODUCTION

Accurate dosing of protamine reversal following on-pump cardiac surgical procedures is challenging, with both excessive and inadequate administration recognised to increase bleeding risk. We aimed to examine the relationship between three ratios for heparin reversal and markers of haemostasis.

METHODS

A retrospective analysis of a prospectively collected database was undertaken at a single tertiary cardiac unit, reviewing all cases of on-pump coronary artery bypass grafts and single valve replacements from 01/01/2011 to 31/12/2015. The ratio between total intra-operative heparin and protamine was stratified to three groups (low: ≤0.6 mg per 100 IU of heparin, moderate: 0.6-1.0 and high: >1.0) and related to the primary outcome of red blood cell (RBC) transfusion, with secondary outcomes being the number of units transfused, the haemoglobin differential and mediastinal drain output at 4 hours.

RESULTS

Of the 803 patients identified, 338 received a blood transfusion, with 1035 units being used. Eighteen percent of individuals (145) received a low ratio, 50% (404) received a moderate ratio and 32% (254) a high ratio. Using the moderate group as a reference, the low dose group was 56.5% less likely to have received a RBC transfusion (OR 0.435; 95% CI 0.270:0.703 p=0.001) while the high dose group carried a 241% increased association with transfusion (OR 3.412; 95% CI 2.399:4.853 p<0.001). For those transfused, a lower protamine:heparin ratio was associated with a lower number of units transfused, lesser haemoglobin differential and less mediastinal drain output.

CONCLUSION

Higher doses of intra-operative protamine relative to heparin are associated with greater risk of transfusion and post-operative bleeding.

Magnesium supplementation: Pharmacokinetics in cardiac surgery patients with normal renal function

BACKGROUND

Intravenous magnesium is routinely administered in intensive care units (ICU) to treat arrhythmias after cardiothoracic surgery. There are no data on the pharmacokinetics of continuous magnesium infusion therapy.

OBJECTIVE

To investigate the pharmacokinetics of continuous magnesium infusion, focusing on serum and urinary magnesium concentration, volume of distribution and half-life.

METHODS

We administered a 10 mmol bolus of magnesium-sulfate followed by a continuous infusion of 3 mmol/h for 12 h in twenty cardiac surgery patients. We obtained blood and urine samples prior to magnesium administration and after one, six, and 12 h.

RESULTS

Median magnesium levels increased from 1.09 (IQR 1.00-1.23) mmol/L to 1.59 (1.45-1.76) mmol/L after 60 min (p < .001), followed by 1.53 (1.48-1.71) and 1.59 (1.48-1.76) mmol/L after 6 and 12 h. Urinary magnesium concentration increased from 9.2 (5.0-13.9) mmol/L to 17 (13.6-21.6) mmol/L after 60 min (p < .001). Cumulative urinary magnesium excretion was 28 mmol (60.9% of the dose given). The volume of distribution was 0.25 (0.22-0.30) L/kg. There were no episodes of severe hypermagnesemia (≥3 mmol/L).

CONCLUSION

Combined bolus and continuous magnesium infusion therapy leads to a significant and stable increase in magnesium serum concentration despite increased renal excretion and redistribution.

Aortic valve sparing root surgery for Marfan syndrome

Aortic valve sparing root surgery (AVSRS) is a safe and durable alternative for patients with dilated roots or pure aortic regurgitation (AR), which avoids the risks of anticoagulation or valvular degeneration with prosthetic valves. Notwithstanding the theoretical challenges of greater tissue fragility in Marfan syndrome (MFS), AVSRS has been demonstrated to have equal outcomes in this condition as it does in those without MFS. The benefits of retaining the native aortic valve in this generally younger age group extend beyond those of avoiding the inconvenience and complications of prolonged exposure to anticoagulants and include ease of management for future aortic, cardiac and non-cardiac procedures which are the norm for these patients. The essential principles of AVSRS in MFS do not differ from those for the rest of the population. Successful repair and durable valve function depend on a sound understanding of the close interaction between the structure and function of this exquisitely designed piece of engineering. We are fortunate to have numerous tools in our surgical armamentarium to preserve these valves. It is the purpose of this paper to demystify the complex structure-function interactions of the aortic valve, thereby gaining an intuition for AVSRS. We will also elaborate on specific technical details of established techniques that we have found successful in preserving the normal function of these valves in the long term.

Systematic review and meta-analysis of surgical outcomes in Marfan patients undergoing aortic root surgery by composite-valve graft or valve sparing root replacement

Background

A major, life-limiting feature of Marfan syndrome (MFS) is the presence of aneurysmal disease. Cardiovascular intervention has dramatically improved the life expectancy of Marfan patients. Traditionally, the management of aortic root disease has been undertaken with composite-valve graft replacing the aortic valve and proximal aorta; more recently, valve sparing procedures have been developed to avoid the need for anticoagulation. This meta-analysis assesses the important surgical outcomes of the two surgical techniques.

Methods

A systematic review and meta-analysis of 23 studies reporting the outcomes of aortic root surgery in Marfan patients with data extracted for outcomes of early and late mortality, thromboembolic events, late bleeding complications and surgical reintervention rates.

Results

The outcomes of 2,976 Marfan patients undergoing aortic root surgery were analysed, 1,624 patients were treated with composite valve graft (CVG) and 1,352 patients were treated with valve sparing root replacement (VSRR). When compared against CVG, VSRR was associated with reduced risk of thromboembolism (OR =0.32; 95% CI, 0.16-0.62, P=0.0008), late hemorrhagic complications (OR =0.18; 95% CI, 0.07-0.45; P=0.0003) and endocarditis (OR =0.27; 95% CI, 0.10-0.68; P=0.006). Importantly there was no significant difference in reintervention rates between VSRR and CVG (OR =0.89; 95% CI, 0.35-2.24; P=0.80).

Conclusions

There is an increasing body of evidence that VSRR can be reliably performed in Marfan patients, resulting in a durable repair with no increased risk of re-operation compared to CVG, thus avoiding the need for systemic anticoagulation in selected patients.

Peripheral venoarterial extracorporeal membrane oxygenation for severe hyperlactataemia after cardiac surgery: a pilot study

BACKGROUND

Severe hyperlactataemia in patients after cardiac surgery is associated with poor prognosis and implies possible splanchnic hypoperfusion. Peripheral venoarterial extracorporeal membrane oxygenation (splanchnic ECMO) may be more effective at reducing lactic acidosis for these patients.

OBJECTIVE

To investigate whether splanchnic ECMO attenuates hyperlactataemia and liver enzyme release in these patients, despite them having a cardiac index > 2 L/min/m² and a mixed venous oxygen saturation > 55%.

DESIGN AND PARTICIPANTS

Retrospective matched case- control study of patients treated with splanchnic ECMO for hyperlactataemia. Seven patients who had had cardiac surgery were treated with splanchnic ECMO compared with seven matched control patients.

RESULTS

We observed a mean decrease in lactate levels from 9.9 mmol/L (SD, 2.9 mmol/L) to 1.4 mmol/L (SD, 0.6 mmol/L) in patients receiving 48 hours of splanchnic ECMO, compared with a mean of 10.4 mmol/L (SD, 2.8 mmol/L) to 4.4 mmol/L (SD, 5 mmol/L) during 48 hours in control patients (P < 0.0001). Normalisation of lactate levels (to < 2 mmol/L) was achieved within a mean of 16.3 hours (SD, 14.6 hours) with splanchnic ECMO, compared with 38.3 hours (SD, 23.8 hours) in the control group (P = 0.029). The median increase in alanine aminotransferase level with splanchnic ECMO was 68% (range, -84% to 2015%) compared with 158% (range: 0%-6024%) (not significant) in control patients.

CONCLUSION

In a selected cohort of patients who had had cardiac surgery with severe post-operative hyperlactataemia, despite an acceptable cardiac index and a mixed venous oxygen saturation, splanchnic ECMO appeared to reduce overall lactate levels and time to normalisation of lactataemia.

Apneic Oxygenation Versus Low-Tidal-Volume Ventilation in Anesthetized Cardiac Surgical Patients: A Prospective, Single-Center, Randomized Controlled Trial

OBJECTIVES

To compare the physiology of apneic oxygenation with low-tidal-volume (VT) ventilation during harvesting of the left internal mammary artery.

DESIGN

Prospective, single-center, randomized trial.

SETTING

Single-center teaching hospital.

PARTICIPANTS

The study comprised 24 patients who underwent elective coronary artery bypass grafting surgery.

INTERVENTIONS

Apneic oxygenation (apneic group: 12 participants) and low-VT ventilation (low-VT group: 12 participants) (2.5 mL/kg ideal body weight) for 15 minutes during harvesting of the left internal mammary artery.

MEASUREMENT AND MAIN RESULTS

The primary endpoint was an absolute change in partial pressure of arterial carbon dioxide (PaCO₂). Secondary endpoints were changes in arterial pH, pulmonary artery pressures (PAP), cardiac index, and pulmonary artery acceleration time and ease of surgical access. The mean (standard deviation) absolute increase in PaCO₂ was 31.8 mmHg (7.6) in the apneic group and 17.6 mmHg (8.2) in the low-VT group (baseline-adjusted difference 14.2 mmHg [95% confidence interval 21.0-7.3], p<0.001). The mean (standard deviation) absolute decrease in pH was 0.15 (0.03) in the apneic group and 0.09 (0.03) in the low-VT group baseline-adjusted difference 0.06 [95% confidence interval 0.03-0.09], p<0.001. Differences in the rate of change over time between groups (time-by-treatment interaction) were observed for PaCO₂ (p<0.001), pH (p<0.001), systolic PAP (p = 0.002), diastolic PAP (p = 0.023), and mean PAP (p = 0.034). Both techniques provided adequate ease of surgical access; however, apneic oxygenation was preferred predominantly.

CONCLUSIONS

Apneic oxygenation caused a greater degree of hypercarbia and respiratory acidemia compared with low-VT ventilation. Neither technique had deleterious effects on PAP or cardiac function. Both techniques provided adequate ease of surgical access.

Total aortic repair: the new paradigm in the treatment of acute type A aortic dissection

The surgical management of acute type A aortic dissection (ATAAD) is in a period of rapid evolution. Understanding the complex physiology and anatomy of both acute and chronic dissection has been enhanced by the ready availability of state of the art imaging techniques. Technical advances in the intraoperative monitoring of organ perfusion, together with adjuncts to limit organ injury and increasing sophistication in open and endovascular surgery have led to a major reduction in both perioperative morbidity and mortality. In many centers, there has been a transition in mindset and surgical approach away from a purely central aortic operation focusing on the ascending aorta and a 'live to fight another day' philosophy. The current more global perspective recognizes the importance of aortic valve function, malperfusion, false lumen (FL) patency and the potential for future complex aneurysm development. The time is now right to transition into the next phase of sophistication in the management of ATAAD with the aim of achieving not only a safe acute operation, but to either entirely prevent chronic complications or to greatly simplify their management by the creation of an anatomical situation that facilitates future endovascular intervention in place of complex re-do surgery. We present our view on the evolution of surgery for ATAAD leading to our current technique of Branch First Arch replacement and Total Aortic Repair, which not only provides a safe immediate operation, but also offers the hope of a simplified future management if not a total cure for the pathology.

Surgical management of acute type A aortic dissection: branch-first arch replacement with total aortic repair

Acute type A dissection (ATAAD) remains a morbid condition with reported surgical mortality as high as 25%. We describe our surgical approach to ATAAD and discuss the indications for adjunct techniques such as the frozen elephant trunk or complete aortic repair with endovascular methods. Arch replacement using the "branch-first technique" allows for complete root, ascending aorta, and arch replacement. A long landing zone is created for proximal endografting with a covered stent. Balloon-assisted intimal disruption and bare metal stenting of all residual dissected aorta to the level of the aortic bifurcation is then performed to obliterate the false lumen (FL) and achieve single true lumen (TL) flow. Additional branch vessel stenting is performed as required.

Treatment of Traumatic False Aneurysm of the Thoracic Aorta with Endoluminal Grafts

Purpose:

Traumatic false aneurysms of the thoracic aorta presenting at a time remote from the original injury are a rare but complex problem. The treatment of a traumatic false aneurysm by endovascular techniques may offer many advantages over conventional open surgery.

Methods and Results:

Two male patients presented with traumatic false aneurysm of the thoracic aorta after being treated emergently for visceral injuries from a gunshot wound in one and an automobile accident in the other. In both cases, the aneurysm was situated so that only the T11 intercostal artery would be sacrificed by endoluminal exclusion. Commercially available endoluminal stent-grafts (Talent) were deployed successfully. Recovery in both patients was rapid and uneventful with no neurological sequelae. Spiral computed tomographic scans at 1 year indicated sustained aneurysm exclusion and satisfactory endograft position.

Conclusions:

A customized endoluminal stent-graft can be used with great accuracy to exclude thoracic false aneurysms, avoiding the potential complexity and morbidity of an open thoracic approach.

Early and Midterm Results with the Ross Procedure: A Study of the First 31 Cases

Between 1994 and 2002, 31 patients underwent the Ross procedure by a single surgeon. The mean age was 42 years (24–61), 87% were male and 61% were in New York Heart Association (NYHA) class III–IV. Pure aortic stenosis (AS) was present in 32% of patients, pure aortic regurgitation (AR) in 22% and mixed disease in the rest. The aortic valve was bicuspid in 93.5% of the patients. Autograft implantation was by full root replacement in all cases. Concomitant cardiac surgical procedures were carried out in 10/31 (32%). All patients had at least annual clinical and echocardiographic follow-ups. There was one early death (3%). Overall patient survival was 92.7% at 1 year and 86.1% at 5 years. Twenty-eight (96.55%) were in NYHA class I. Echocardiographic follow-up revealed none to trivial AR in 24/29 (82.75%) and mild AR in 4/29 (13.7%). There was no autograft re-operation before 5 years. The mean gradient across the autograft was low (< 4 mm Hg). There were no incidences of endocarditis or thromboembolism. None of the patients required anticoagulation. Our early experience with the Ross procedure has shown good results in relation to early and midterm morbidity, mortality, autograft, and homograft function.