Cerebral protection during aortic arch surgery can be performed using various surgical strategies. We retrospectively analyzed our results of different brain protection modalities during aortic arch ...surgery.
Between January 2003 and November 2009, 636 consecutive patients underwent aortic arch replacement surgery using unilateral antegrade cerebral perfusion (UACP n=123), bilateral antegrade cerebral perfusion (BACP n=242), retrograde cerebral perfusion (RCP n=51), or deep hypothermia and circulatory arrest (DHCA n=220). Mean age of patients was 62±14 years, 64% were male, 15% were reoperations, and 37% were performed for acute type A dissections. Mean follow-up was 4.9±0.1 years and was 97% complete.
Circulatory arrest time was 22±17 minutes UACP, 23±21 minutes BACP, 18±12 minutes RCP, and 15±13 minutes DHCA; p<0.001). Early mortality was 11% (n=72) and was not different between the surgical groups. Stroke rate was 9% for ACP patients (n=33) versus 15% (n=39) for patients who did not receive ACP (p=0.035). Independent predictors of stroke were type A aortic dissection (odds ratio OR, 1.9; 95% confidence interval CI, 1.3 to 3.2; p<0.001), age (OR, 1.04; 95% CI, 1.01 to 1.06; p=0.001), duration of circulatory arrest (OR, 1.01, 95% CI, 1.002 to 1.03; p=0.02), and total aortic arch replacement (OR, 2.7; 95% CI, 1.3 to 5.7; p=0.005). Five year survival was 68%±4% and was not significantly different between groups.
Antegrade cerebral perfusion is associated with significantly less neurologic complications than RCP and DHCA, despite longer circulatory arrest times. Medium-term survival is worse for patients with postoperative permanent neurologic deficit and preoperative type A aortic dissection.
Combined analysis of SPECT myocardial perfusion imaging (MPI) performed with a solid-state camera on patients in 2 positions (semiupright, supine) is routinely used to mitigate attenuation artifacts. ...We evaluated the prediction of obstructive disease from combined analysis of semiupright and supine stress MPI by deep learning (DL) as compared with standard combined total perfusion deficit (TPD).
1,160 patients without known coronary artery disease (64% male) were studied. Patients underwent stress
Tc-sestamibi MPI with new-generation solid-state SPECT scanners in 4 different centers. All patients had on-site clinical reads and invasive coronary angiography correlations within 6 mo of MPI. Obstructive disease was defined as at least 70% narrowing of the 3 major coronary arteries and at least 50% for the left main coronary artery. Images were quantified at Cedars-Sinai. The left ventricular myocardium was segmented using standard clinical nuclear cardiology software. The contour placement was verified by an experienced technologist. Combined stress TPD was computed using sex- and camera-specific normal limits. DL was trained using polar distributions of normalized radiotracer counts, hypoperfusion defects, and hypoperfusion severities and was evaluated for prediction of obstructive disease in a novel leave-one-center-out cross-validation procedure equivalent to external validation. During the validation procedure, 4 DL models were trained using data from 3 centers and then evaluated on the 1 center left aside. Predictions for each center were merged to have an overall estimation of the multicenter performance.
718 (62%) patients and 1,272 of 3,480 (37%) arteries had obstructive disease. The area under the receiver operating characteristics curve for prediction of disease on a per-patient and per-vessel basis by DL was higher than for combined TPD (per-patient, 0.81 vs. 0.78; per-vessel, 0.77 vs. 0.73;
< 0.001). With the DL cutoff set to exhibit the same specificity as the standard cutoff for combined TPD, per-patient sensitivity improved from 61.8% (TPD) to 65.6% (DL) (
< 0.05), and per-vessel sensitivity improved from 54.6% (TPD) to 59.1% (DL) (
< 0.01). With the threshold matched to the specificity of a normal clinical read (56.3%), DL had a sensitivity of 84.8%, versus 82.6% for an on-site clinical read (
= 0.3).
DL improves automatic interpretation of MPI as compared with current quantitative methods.
Hypothermic oxygenated machine perfusion improves outcomes in Liver Transplantation, but application is limited as O2 is supplied by a stationary circuit. A novel technique of O2 “pre-charge” in a ...portable pump would broaden use and further mitigate ischemia damage from organ transport.
Porcine DCD livers were randomized to static cold storage (SCS, n = 8) or hypothermic machine perfusion (HMP). HMP was stratified into HMP-O2 (n = 5), non-O2 open to air HMP-RA (n = 5), and non-O2 with sealed lids or no air HMP-NA (n = 5). HMP-O2 was “pre-charged” using 100% O2 delivered at 10 L/min over 15 min. Perfusate and tissue O2 tension (pO2), liver biopsies, and fluid chemistries were analyzed.
“Pre-charge” achieves sustained tissue and perfusate pO2 vs others. HMP-O2 results in decreased markers of hepatocyte injury: ALT (p < 0.05) and LDH (p < 0.05), lower expression of CRP and higher expression of SOD1 vs SCS. This suggests decreased inflammation and improved ROS scavenging.
“Pre-charge” is an effective technique, which allows portability and transport without an O2 source and improves graft parameters.
•Oxygen “pre-charge” by 100% O2 for 15 min achieves high, persistent oxygen levels for perfusion.•HMP treatment leads to significant decrease in markers of injury: ALT and sCD-146.•Pre-charged HMP-O2 results in improved aerobic metabolism: decreased LDH.•HMP results in downregulation of CRP expression, a nonspecific marker of inflammation.•HMP results in upregulation of SOD1 expression, an ROS scavenger.
Cross-circulation of plasma from a paracorporeal animal allows successful ex vivo heart perfusion (EVHP) for 3 days. Little is known about the feasibility of prolonged EVHP without a paracorporeal ...animal. These experiments evaluated plasma exchange (PX) that infuses fresh plasma, whereas an equal amount is removed to replace paracorporeal cross-circulation.
Ten hearts were procured from 8 to 10 kg piglets and maintained with EVHP. The EVHP circuit was primed with platelet- and leukocyte-reduced blood. Plasma obtained from stored porcine blood (4°C for ≤7 days) was infused and removed with a plasma separator at 1 mL/h/g cardiac tissue (n = 5) in the PX group. Controls (n = 5) used the same EVHP without PX. Antegrade aortic perfusion was adjusted to reach physiologic coronary flow of 0.7 to 1.2 mL/min/g, normothermia (37°C), and hemoglobin ≥8 g/dL. Viability was assessed by hemodynamic metrics, metabolic assays, and histopathology.
All PX hearts remained viable for 24 hours compared with only 1 control (P = .015). Coronary resistance was higher in the PX versus controls (1.06 ± 0.06 mm Hg/mL/min; 0.58 ± 0.02 mm Hg/mL/min P < .05). Lactate levels were lower in PX (2.8-4.2 mmol/L) versus controls (3.6-7.6 mmol/L) (P < .05). PX demonstrated a trend toward preservation of left ventricle systolic pressure (63.0 ± 10.9 mm Hg) versus controls (37 ± 22.0 mm Hg) (P > .05). In mixed effect models, oxygen consumption was higher with PX (P < .05). Histopathologic evaluation confirmed extensive myocardial degeneration and worse interstitial edema in controls.
These results demonstrate that EVHP can be successfully maintained for at least 24 hours using continuous PX. This eliminates the need for a paracorporeal animal and provides an important step toward clinical application.
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Quantification of myocardial blood flow requires knowledge of the amount of contrast agent in the myocardial tissue and the arterial input function (AIF) driving the delivery of this contrast agent. ...Accurate quantification is challenged by the lack of linearity between the measured signal and contrast agent concentration. This work characterizes sources of non-linearity and presents a systematic approach to accurate measurements of contrast agent concentration in both blood and myocardium.
A dual sequence approach with separate pulse sequences for AIF and myocardial tissue allowed separate optimization of parameters for blood and myocardium. A systems approach to the overall design was taken to achieve linearity between signal and contrast agent concentration. Conversion of signal intensity values to contrast agent concentration was achieved through a combination of surface coil sensitivity correction, Bloch simulation based look-up table correction, and in the case of the AIF measurement, correction of T2* losses. Validation of signal correction was performed in phantoms, and values for peak AIF concentration and myocardial flow are provided for 29 normal subjects for rest and adenosine stress.
For phantoms, the measured fits were within 5% for both AIF and myocardium. In healthy volunteers the peak Gd was 3.5 ± 1.2 for stress and 4.4 ± 1.2 mmol/L for rest. The T2* in the left ventricle blood pool at peak AIF was approximately 10 ms. The peak-to-valley ratio was 5.6 for the raw signal intensities without correction, and was 8.3 for the look-up-table (LUT) corrected AIF which represents approximately 48% correction. Without T2* correction the myocardial blood flow estimates are overestimated by approximately 10%. The signal-to-noise ratio of the myocardial signal at peak enhancement (1.5 T) was 17.7 ± 6.6 at stress and the peak Gd was 0.49 ± 0.15 mmol/L. The estimated perfusion flow was 3.9 ± 0.38 and 1.03 ± 0.19 ml/min/g using the BTEX model and 3.4 ± 0.39 and 0.95 ± 0.16 using a Fermi model, for stress and rest, respectively.
A dual sequence for myocardial perfusion cardiovascular magnetic resonance and AIF measurement has been optimized for quantification of myocardial blood flow. A validation in phantoms was performed to confirm that the signal conversion to gadolinium concentration was linear. The proposed sequence was integrated with a fully automatic in-line solution for pixel-wise mapping of myocardial blood flow and evaluated in adenosine stress and rest studies on N = 29 normal healthy subjects. Reliable perfusion mapping was demonstrated and produced estimates with low variability.
To compare the outcomes of livers donated after circulatory death (DCD) and undergoing either in situ normothermic regional perfusion (NRP) or ex situ normothermic machine perfusion (NMP) with livers ...undergoing static cold storage (SCS).
DCD livers are associated with increased risk of primary nonfunction, poor function, and nonanastomotic strictures (NAS), leading to underutilization.
A single center, retrospective analysis of prospectively collected data on 233 DCD liver transplants performed using SCS, NRP, or NMP between January 2013 and October 2020.
Ninety-seven SCS, 69 NRP, and 67 NMP DCD liver transplants were performed, with 6-month and 3-year transplant survival (graft survival non-censored for death) rates of 87%, 94%, 90%, and 76%, 90%, and 76%, respectively. NRP livers had a lower 6-month risk-adjusted Cox proportional hazard for transplant failure compared to SCS (hazard ratio 0.30, 95% Confidence Interval 0.08-1.05, P = 0.06). NRP and NMP livers had a risk-adjusted estimated reduction in the mean model for early allograft function score of 1.52 (P < 0.0001) and 1.19 (P < 0.001) respectively compared to SCS. Acute kidney injury was more common with SCS (55% vs 39% NRP vs 40% NMP; P = 0.08), with a lower risk-adjusted peak-to-baseline creatinine ratio in the NRP (P = 0.02). No NRP liver had clinically significant NAS in contrast to SCS (14%) and NMP (11%, P = 0.009), with lower risk-adjusted odds of overall NAS development compared to SCS (odds ratio = 0.2, 95%CI 0.06-0.72, P = 0.01).
NRP and NMP were associated with better early liver function compared to SCS, whereas NRP was associated with superior preservation of the biliary system.
To date, no consensus exists regarding indication, technique, or efficacy of distal perfusion cannulae (DPC) in preventing limb ischemia among patients receiving venoarterial extracorporeal membrane ...oxygenation (VA‐ECMO). We aim to examine the available literature and report association between DPC and risk of limb ischemia. PubMed/Medline, Scopus, Cochrane Central Register of Controlled Trials, Google Scholar, and bibliographies of included studies were searched from database inception until August 2016. Original studies describing the DPC placement technique and incidence of limb ischemia following DPC placement among VA‐ECMO patients were included for systematic review. Studies with a comparison group of patients without DPC were included for meta‐analysis. Two authors independently screened title/s, reviewed full texts, and extracted data from the eligible studies. Meta‐analysis was performed using the Mantel‐Haenszel method under a random‐effects model. Statistical heterogeneity was examined with the I2 statistic (RevMan Version 5.3). Of 542 title/s screened, 62 full text articles were selected for review, yielding 22 retrospective observational studies, for a total of 779 patients with 132 limb ischemia events. There was significant variation in DPC indication, cannula type, and placement technique among the studies. Compared to no DPC, the presence of a DPC was associated with at least a 15.7% absolute reduction in the incidence of limb ischemia (9.74 vs. 25.42%; risk ratio 0.41; 95% confidence interval 0.26–0.65, P < 0.01; heterogeneity statistic I2 = 28%). There was no statistically significant difference in mortality in the pooled dataset comparing DPC versus no DPC. In adults treated with VA‐ECMO, DPC placement was associated with a lower incidence of limb ischemia. Currently no consensus guidelines exist regarding indication for DPC placement. Given the association described in this analysis, future prospective trials are warranted to establish a causal relationship and optimal technique for the use of DPC in patients treated with VA‐ECMO.
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