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Page 10 of 19 Khokhar et al. Mini-invasive Surg 2022;6:2 https://dx.doi.org/10.20517/2574-1225.2021.97

Table 1. Overview of hemodynamic indices to quantify extent of aortic regurgitation during transcatheter aortic valve replacement
Index Formula Cut-off
Aortic regurgitation index (ARI) ARI = (DD/systolic aortic pressure) × 100 ARI < 25 associated with increased mortality
Aortic regurgitation index ratio ARI ratio = ARI post-implant/ARI pre-implant ARI ratio < 0.60 associated with increased
mortality
Diastolic delta (DD) Diastolic aortic pressure - left ventricular end diastolic DD < 18 mmHg associated with increased
pressure mortality
Heart-rate (HR) adjusted diastolic (DD/heart rate) × 80 HR-DD < 25 associated with increased
delta mortality

If despite balloon dilatation, PVL is severe or is associated with significant hemodynamic compromise, then
[48]
a second THV can be implanted as a TAVR-in-TAVR procedure, with a BEV preferred . In more stable
cases, or if discovered later post-procedurally, then elective closure with vascular plugs should be
[43]
considered .

ACUTE KIDNEY INJURY
Post-TAVR acute kidney injury (AKI) can be diagnosed by measuring the increase in serum creatinine or
reduction in urine output as specified in the VARC-2 criteria, which are based on the Acute Kidney Injury
[1]
Network definitions . Depending on the cohort, the overall incidence of AKI ranges 10%-40%, with stage 3
AKI observed in around 1% of patients undergoing TAVR [3,90-92] . Encouragingly, the incidence of AKI in
contemporary cohorts is down to around 10%, which may reflect the changes in clinical profile of patients
undergoing TAVR or be related to improvements in procedural techniques . However, numerous studies
[92]
have consistently shown that the development of post-TAVR AKI is associated with adverse acute and
longer-term morbidity, mortality, and quality of life [3,90-92] . A recent report of 107,814 patients from the
society of thoracic surgeons TAVR registry in the USA demonstrated an elevated risk of one-year mortality
associated with stage 1 (HR = 2.7, 95%CI: 2.5-2.8), stage 2 (HR = 10.4, 95%CI: 7.0-15.4), and stage 3 (HR =
7.0, 95%CI: 6.0-8.2) AKI .
[92]

Multiple patient-related and procedural factors are implicated in the development of post-TAVR AKI.
Baseline renal dysfunction is one of the strongest independent risk factors for the long-term mortality and
development of post-TAVR AKI [90,92,93] . In addition, patients with cardiovascular and non-cardiovascular co-
morbidities, including anemia, diabetes, chronic obstructive pulmonary disease, severe inflammatory
response syndrome, and aortic or peripheral vascular disease, are at increased risk [90,93-96] .

During the TAVR procedure, the kidneys can be prone to injury either due to hemodynamic instability
during rapid pacing, significant bleeding, and prosthesis deployment or due to embolism of atherosclerotic
or calcific micro-fragments during catheter manipulation. Managing complications may require an
increased use of contrast, conversion to general anesthesia, and open-heart surgery or requirement for red
blood cell transfusions, which can further increase the risk of AKI . Furthermore, choice of TAVR valve
[93]
and access route can be important with a higher incidence of AKI observed following the use of self-
[95]
expandable vales and direct apical or aortic access .

The association between the type and volume of contrast agent used and subsequent risk of AKI following
TAVR is less clear. Use of a low-osmolar vs. iso-osmolar contrast agent during TAVR did not alter the
incidence of AKI. Similarly, the total contrast volume used during the procedure was found to have no
impact on development of AKI in several studies. However, when contrast volume was indexed to baseline
renal function, then the amount of contrast used was predictive of both AKI and mortality [97,98] .