The impact of the COVID-19 pandemic on transcatheter aortic valve implantation (TAVI) service: a United Kingdom tertiary centre experience

Background/Introduction

Untreated, symptomatic, severe aortic stenosis carries significant mortality and morbidity. Timely intervention is pivotal to ensure patient safety. The COVID-19 pandemic created unprecedented challenges to the UK's National Health Service (NHS), resulting in the deferral of all elective work, including TAVI services from March 2020.

Purpose

To evaluate clinical outcomes and time delays in patients undergoing TAVI during the pandemic period compared to an age and risk factor-matched cohort of patients prior to COVID-19. We hypothesized that there were significant time delays, more emergency procedures and related adverse outcomes in patients who underwent TAVI during the pandemic period.

Methods

We analysed prospectively collected data (patient characteristics, procedural details, complications and in-hospital outcomes) of 210 consecutive patients who underwent TAVI between March 2019 and February 2021 in a tertiary centre in the UK (The centre serves for a population of 2.5 million and provided in-patient treatment for 5590 COVID-positive patients over a 12 month period). We compared time-lags from an initial referral to outpatient review, CT aortograms, valve implantation and 30-day mortality between patients who underwent TAVI between March 2019 and Feburary 2020 (N=134) and those who underwent TAVI between March 2020 and February 2021 (COVID Group=76).

Results

The mean age of the cohort was 81.4±6.6 years and majority were females (51%) and were in moderate risk category (EuroSCORE II=4.55±5.5). Of the total cohort, 4 (5.3%) patients acquired COVID-19 pneumonia during the hospital stay. The age, cardiovascular comorbidities and risk scores were comparable between the control group and the COVID cohort. (Table 1). There were no significant differences in procedural complications in the control group compared to the COVID-19 group (Table 1). The median waiting time from referral to TAVI clinic was significantly shorter in the COVID-19 group (33 (8–66) vs. 51 (17–89) days (P=0.04)) and there was no significant difference in time delays for CT aortogram, MDT or TAVI procedure between the two groups. The median length of stay (2 (2–4) vs 2.5 (2–9) days) and 30 day mortality (1.4% vs 5.3%) was comparable between the two groups (Table 1).

Conclusion

Contrary to our hypothesis, our analysis demonstrated that there were no significant time delays, excess complications or mortality in TAVI procedures during the COVID-19 pandemic period despite the excess burden imposed on our local health services. More importantly, very few TAVI patients acquired COVID-19 infection during in-hospital stay. This is likely due to prompt identification of innovative ways of re-configuring an existing local patient pathway, by the TAVI team, to deliver safe and uninterrupted TAVI services during this unprecedented pandemic setting.

Funding Acknowledgement

Type of funding sources: None. Figure 1. Referral times

X-ray crystallographic and kinetic investigations of 6-sulfamoyl-saccharin as a carbonic anhydrase inhibitor

Sulfamoylated saccharin binds to human carbonic anhydrase II through the SO₂NH₂and not CONHSO₂moiety.

Extra- and intra-cellular lytic effects of Cytophaga sp. LR2 on the red microalgae Rhodella reticulata

AIMS

To evaluate the lytic activities of crude enzymes from Cytophaga sp. LR2 on Rhodella reticulata cells and isolated algal polysaccharide.

METHODS AND RESULTS

The Cytophaga compartment was separated after centrifugation in a cell suspension for 30 min at 18,000 g. The extracellular enzyme was obtained from the supernatant and the intracellular from the pelleted cells after sonication and removal of debris. Algal cells were incubated with extra- or intracellular preparations and sowed onto agar medium. The suppressive effect of the extracellular enzyme on colony-forming units was found to be almost twice as high. The result was still more pronounced when treated cells had been shocked osmotically before seeding. Saccharolytic activity was evaluated by changes in the reducing sugars in the media. Concerning isolated algal polysaccharide, the reducing power of the two bacterial preparates was relatively low. A combined fraction showed the highest lytic activity. Using native and SDS electrophoresis some relation between the prevalence of the extra and intracellular protein patterns was registered. Two of the common components' molecular weight masses of 50 and 21 kDa were found to be reproducible in native- and SDS-containing gel.

CONCLUSIONS

Cytophaga sp. LR2 produce extra- and intracellular enzymes active in destroying Rhodella cultures. The agents excreted in the medium are more effective.We suppose that two or three different classes of enzymes are involved in the lysis process. The comparative electrophoresis in this case shows the protein components with predictable functions.

SIGNIFICANCE AND IMPACT OF THE STUDY

Combining different simple and reproducible approaches to identify the lytic capability of Cytophaga sp. LR2 on R. reticulata.

Influence of physiological factors on the lysis effect of Cytophaga on the red microalga Rhodella reticulata

The influence of different factors on the lysis of the red microalga, Rhodella reticulata, by Cytophaga sp. LR2 was studied. The pathogenic bacterial strain was more resistant than the alga to the physiological parameters studied, which assured long-term survival of bacteria in algal cultures. Cytophaga sp. LR2 infected R. reticulata at temperatures between 15 and 30 degrees C, in the illuminated as well as the non-illuminated cultures, at pH values between 5.0 and 9.0, and in the presence of NaCl and CaCl2 in the culture medium. SEM showed a different morphology of the bacteria in algal cultures from those of axenic cultures of Cytophaga. Observations of specific associations between algal and bacterial cells revealed that the role of the slime extrusions on the bacterial surface was attachment of Cytophaga to algal cells, and that their clumping leads to rapid lysis.

The futility of common firewall policies: an experimental demonstration

Many healthcare organizations utilize network "firewalls" to protect their networks from being accessed by unauthorized external entities. These same firewalls are also often configured to deny access to certain external services from within the internal network. The latter policy can be subverted through a "protocol tunneling" strategy, which has been implemented as a set of programs called "Firehole." Organizations should be aware of this potential weakness in their network security designs. Policies that deny external services to users should be carefully evaluated in light of clearly defined organizational goals.