Sequentially addressable dielectrophoretic array for high-throughput sorting of large-volume biological compartments

Droplet microfluidics has become a powerful tool in precision medicine, green biotechnology, and cell therapy for single-cell analysis and selection by virtue of its ability to effectively confine cells. However, there remains a fundamental trade-off between droplet volume and sorting throughput, limiting the advantages of droplet microfluidics to small droplets (<10 pl) that are incompatible with long-term maintenance and growth of most cells. We present a sequentially addressable dielectrophoretic array (SADA) sorter to overcome this problem. The SADA sorter uses an on-chip array of electrodes activated and deactivated in a sequence synchronized to the speed and position of a passing target droplet to deliver an accumulated dielectrophoretic force and gently pull it in the direction of sorting in a high-speed flow. We use it to demonstrate large-droplet sorting with ~20-fold higher throughputs than conventional techniques and apply it to long-term single-cell analysis of Saccharomyces cerevisiae based on their growth rate.

P224 Valvuloplasty treatment and three-dimensional analysis for isolated cleft of the anterior mitral valve leaflet: a case report

Introduction: Isolated cleft of the anterior mitral valve leaflet is a very rare congenital disease and a cause of mitral regurgitation

not associated with atrioventricular septal defect. In this case, we report our experience in valvuloplasty treatment for mitral regurgitation with this rare aetiology.

Case description

23-year-old Russian women. Although cardiac murmur was pointed out in her childhood and she was diagnosed as mitral regurgitation, she refused treatment. After getting married with a Japanese man and moving to Japan, her symptoms had worsened and she visited our hospital for treatment. Preoperative transthoracic echocardiography (TTE) had indicated the regurgitation from the central part of the mitral valve. Preoperative transoesophageal echocardiography (TOE) had pointed out the isolated cleft of the anterior mitral valve.

Surgical mitral valvuloplasty was scheduled, and the TOE after anaesthetic induction showed the isolated cleft of the anterior mitral valve the same as in the preoperative period and pointed out the posterior leaflet billowing. The operative finding was also similar to TOE: the largely bisected central anterior mitral valve and billowing, P2 billowing, shortening of P1 and P3, P2-3 cleft. There were no chords at the anterior cleft. The valvuloplasty was performed including five-time pump runs in total: 1) Continuous suture for the anterior cleft and ring annuloplasty were performed, and the regurgitation was seemed to be almost controlled at the water-leak test and the ink test; 2) Artificial chordae and leaflet plications were added to residual regurgitation from the posterior region; 3)The residual regurgitation was controlled to Mild but it became a lateral jet toward the ring; 4)Mild remnant flow was pointed out: the regurgitation seemed to be from the posterior cleft, where immediately below the ring suture; 5) Pericardium patch was added and the remnant flow was almost eliminated. The pump was weaned and the operation was finished without any problems.

Discussion

The cause of difficulty in this valvuloplasty was thought to be caused by the difficulty in evaluating the mitral valve morphology. It was evident that the anterior leaflet of the mitral valve was largely bisected. However, it was difficult to evaluate the coaptation line and area due to the absence of chordal cords in the anterior cleft and the billowing or shortening of the posterior leaflet. Although preoperative three-dimensional analysis helped evaluating the isolated cleft and the regurgitation was almost controlled in the evaluation in the operation field, nevertheless, a residual regurgitation occurred and indicated in the TOE after re-beating.

Conclusion

It is important and necessary to use fine evaluation of coaptation is needed in valvuloplasty for isolated cleft of the anterior mitral valve leaflet; not only apply three-dimensional analysis but also apply two-dimensional echocardiogram.

Abstract P224 Figure.

P662 Synchrony between the right and left heart systems is recovered after TAVI in patients with severe aortic stenosis

Funding Acknowledgements

Young Investigator Grant of Japanese Society of Cardiovascular Anesthesia

Background / Introduction

Evidences have shown that cardiac function decline and systolic phase change are caused by massive afterload of the stenosed aortic valve in patients with severe aortic valve stenosis. As a result of the reduction of the left ventricular afterload by valve replacement, the cardiac function recovers. However, it has not been clarified yet how the changes in cardiac function affect the relationship between the right and left heart systems, as well as the systole phase.

TAPSE and MAPSE are known as indices of simple cardiac function evaluation by measuring the movement distance of the atrioventricular annulus. We obtained these indices (i.e. TAPSE, MAPSE) within the same heartbeat using speckle tracking analysis of the atrioventricular annulus and evaluated the changes in cardiac function and phase between the right and left heart systems.

Purpose

To reveal the relationship of cardiac function and time phase between the right and left heart systems by evaluating the maximum movement distance and time of the atrioventricular annulus within the same heartbeat and the same view in patients with severe aortic valve stenosis before and after TAVI.

Methods

A prospective cohort study was conducted. We recruited and analyzed 44 patients with severe aortic valve stenosis who received TAVI treatment, able to record baseline before treatment and follow-up 6 months and 12 months after treatment at our hospital from March 2017 to May 2019. Patients were excluded if more than 2 degree of atrioventricular valve regurgitation or incomplete data. The apical four-chamber view was used for speckle tracking analysis with the origin of the apical extension and region of interest (ROI) of the mitral annulus and tricuspid annulus. For each patient before treatment, at 6 months and 12 months after treatment, the maximum contraction distance (DM), maximum contraction time (TM) of the mitral valve annulus, maximum contraction distance (DT) and maximum contraction time (TT) of the tricuspid annulus were measured. Maximum contraction distance ratio (DM/ DT) and maximum contraction time ratio (TM/ TT) were calculated. For statistical analysis, t-test and ANOVA were used, and a significance threshold of p &lt;0.05 was applied.

Results

TM/ TT decreased at 12 months after TAVI, and DM/ DT increased significantly at 6 months and 12 months after TAVI when compared to baseline before treatment.

Conclusions

In patients with severe aortic valve stenosis, the correction of cardiac function difference between the right and left heart systems occurs from 6 months after TAVI. Moreover, the correction of contraction phase difference between the right and left heart systems at 12 months after TAVI. Thus, the synchrony between the right and left heart system is recovered 12 months after TAVI.

Abstract P662 Figure.

P5608Acute respiratory failure after type A aortic dissection repair: data from the International Registry of Aortic Dissection (IRAD)

Background

Acute Respiratory Failure (ARF) has been noted in up to 20% of patients undergoing cardiac surgery and is associated with increased mortality. Cardiopulmonary bypass (CPB) is often followed by pulmonary dysfunction, although literature on the subject in the setting of Type A acute aortic dissection (TAAAD) is limited.

Methods

This study identified the incidence of ARF after TAAAD, associated risk factors, and the impact of ARF on early and late outcomes. All data have been derived from the International Registry of Acute Aortic Dissection (IRAD).

Results

Postoperative ARF (defined as ventilator support for ≥3 days, tracheostomy, and/or pneumonia) occurred in 434 (24.6%) of 1764 surgically managed TAAAD patients (mean age 60.1±14.2 years) from November 2001 until November 2017. Peripheral vessel procedures (6.4% v 2.8%, p=0.002), cerebral perfusion (89.2% v 82.3%, p<0.001), use of hypothermic circulatory arrest (93% v 87.7%), longer arrest time (median 39 (Q1-Q3 27–128 minutes) v 31 (Q1-Q3 22.0–52.9 minutes)), and lower extremity ischemia (18.8% v 6.7%, p<0.001) were more common in ARF patients.

On multivariable logistic regression analysis, age ≥70 years (OR 1.019, 95% CI 1.005–1.034, p=0.008), current smoking (OR 1.744, 95% CI 1.184–2.570, p=0.005), peripheral vessel procedures (OR 2.457, 95% CI 1.132–5.334, p=0.023), presenting hypotension/shock (OR 2.036, 95% CI 1.336–3.102, p=0.001), lower extremity ischemia at surgery (OR 2.77, 95% CI 1.574–4.875, p<0.001), concomitant coronary artery bypass graft (CABG) (OR 2.982, 95% CI 1.597–5.568, p=0.001), pre-operative acute renal failure (OR 2.532, 95% CI 1.350–4.749, p=0.004), and prolonged circulatory arrest time in minutes (OR 1.005, 95% CI 1.003–1.007, p<0.001) were independently associated with ARF development. Patients with aortic valve replacement (AVR) were less likely to develop ARF (OR 0.497, 95% CI 0.308–0.802, p=0.004).

Post-operative complications were more common in ARF patients. In-hospital mortality was higher in the ARF cohort (16.4% v 4.7%, p<0.001). Multivariable logistic regression identified ARF (OR 2.686, 95% CI 1.647–4.381, p<0.001) as well as pre-operative hypotension (OR 1.89, 95% CI 1.130–3.159, p=0.015), lower extremity ischemia (OR 2.77, 95% CI 1.545–4.998, p=0.001), pre-operative myocardial infarction (OR 3.141, 95% CI 1.058–9.33, p=0.039), and CABG (OR 1.988, 95% CI 1.011–3.909, p-value 0.047) as independent predictors of death.

Conclusions

Post-operative ARF is common after TAAAD repair; in-hospital complications and death are higher in this cohort.

Acknowledgement/Funding

W.L. Gore & Associates, Inc.; Medtronic; Varbedian Aortic Fund; Hewlett Foundation; Mardigian Foundation; UM Faculty Group Practice; Ann & Bob Aikens