A structured pre-procedural risk mitigation strategy for ultra-high-risk TAVR in a nonagenarian with extreme aortic valve calcification: a case report using a balloon-expandable valve and proactive ECMO backup

Abstract

Background

Transcatheter aortic valve replacement (TAVR) in nonagenarians with extensive aortic valve calcification is associated with a substantial risk of intraprocedural circulatory collapse.

Case presentation

This case report describes a structured pre-procedural risk mitigation strategy integrating a balloon-expandable valve system and a pre-emptive, “wet-prepared” extracorporeal membrane oxygenation (ECMO) backup. A 97-year-old man with severe symptomatic aortic stenosis (peak velocity = 4.76 m/s; aortic valve calcium volume = 1178 mm³) underwent transfemoral TAVR using a structured approach incorporating precision imaging, careful device selection using a domestic Chinese balloon-expandable valve system (Prizvalve^® TAV23), proactive ECMO preparedness, and multidisciplinary team coordination. Immediately after valve deployment, the patient developed circulatory collapse (blood pressure = 40/20 mmHg). A predefined emergency protocol was promptly activated. Following chest compressions, vasopressor administration, and pacing optimization, spontaneous circulation was restored within minutes. Angiography confirmed stable valve positioning with satisfactory expansion. At 3-month follow-up, echocardiography demonstrated absence of paravalvular leakage and preserved left ventricular systolic function.

Conclusions

This case demonstrates the feasibility of a structured, pre-procedural risk mitigation strategy for TAVR in an exceptionally high-risk patient. The approach enabled the management of intraprocedural circulatory collapse. In this setting, the balloon-expandable valve platform demonstrated procedural characteristics that were well suited for this complex anatomy.

Supplementary Information

The online version contains supplementary material available at https://doi.org/10.1186/s13019-026-04615-7.

Background

Aortic stenosis (AS) is the most common valvular heart disease in older adults, with the prevalence of severe disease exceeding 4% among individuals aged ≥ 85 years. Super-octogenarians (≥ 90 years) often face prohibitive surgical risk due to frailty, multimorbidity, and reduced organ reserve. Current guidelines recommend transcatheter aortic valve replacement (TAVR) as a Class I, Level A treatment option for symptomatic severe AS in appropriately selected elderly patients [1, 2]. Nevertheless, extensive aortic valve calcification, particularly when calcium volume exceeds 1000 mm³, poses unique challenges, including risks of annular rupture, coronary obstruction, and catastrophic circulatory collapse. Current management strategies often remain reactive.

This report describes the successful treatment of a 97-year-old patient with severe calcific AS using a structured pre-procedural risk mitigation strategy that combined detailed anatomical planning, selection of a balloon-expandable valve platform, and proactive preparation for mechanical circulatory support. The case highlights the potential value of shifting from crisis management to pre-emptive risk control.

Case presentation

A 97-year-old man presented with recurrent angina of more than 2 weeks’ duration, with progressive worsening before admission. His medical history was significant for grade 3 hypertension, chronic kidney disease (estimated glomerular filtration rate = 35 mL/min/1.73 m²), and frailty. Frailty assessment using the Clinical Frailty Scale (Rockwood scale) yielded a score of 6/9, consistent with moderately severe frailty and reflecting limited mobility and dependence in instrumental activities of daily living. His body mass index was 19.8 kg/m². Physical examination revealed a systolic ejection murmur and basal crackles. Transthoracic echocardiography demonstrated severe AS, with a peak transvalvular velocity of 4.76 m/s, a mean gradient of 54 mmHg, an effective orifice area of 0.38 cm², and a preserved left ventricular ejection fraction of 64% [3].

Coronary computed tomography (CT) angiography demonstrated non-obstructive coronary artery disease, with a total coronary calcium score of 253. Pre-procedural aortic CT angiography was performed using a GE Revolution CT scanner. Images were reconstructed at 75% of the RR interval during diastole, and calcium volume was quantified using dedicated post-processing software (3mensio Structural Heart, Pie Medical Imaging) with a threshold of > 130 Hounsfield units. The examination revealed a tricuspid aortic valve with extensive calcification and a total calcium volume of 1178 mm³, predominantly involving the commissural regions. The annular diameter measured 25.6 mm, while the left ventricular outflow tract diameter measured 26.1 mm (Figs. 1 and 2). Coronary ostial heights were 13.4 mm and 13.6 mm for the left and right coronary arteries, respectively, both originating from the left coronary sinus, suggesting a low risk of coronary obstruction. The right femoral artery demonstrated a minimum diameter of 7.1 mm and was considered suitable for transfemoral access. Overall, the anatomical findings supported the feasibility of transfemoral TAVR.

Fig. 1.

Quantitative computed tomographic analysis of the aortic root

Fig. 2.

Annular and left ventricular outflow tract measurements for transcatheter heart valve sizing

Therapeutic decision‑making

Following multidisciplinary heart team review, surgical aortic valve replacement was considered prohibitively high risk, with a Society of Thoracic Surgeons predicted risk of mortality > 15%. Consequently, TAVR was selected as the preferred treatment strategy. Given the extensive calcific burden and the patient’s complex anatomy, a balloon-expandable valve platform was chosen. A Prizvalve^® TAV23 device, a domestic Chinese balloon-expandable valve with an 18-mm stent frame height, was selected because of its short frame design. A deliberate oversizing strategy was planned, involving implantation of a 23-mm valve within a 25.6-mm annulus, corresponding to an estimated oversizing ratio of approximately 10%. In parallel, a proactive circulatory support strategy was established through a “wet-prepared” extracorporeal membrane oxygenation (ECMO) system with pre-positioned femoral arterial and venous access [4].

Procedural details

The procedure was performed under general anesthesia via transfemoral access. Ultrasound-guided vascular access was obtained, and a 20 F sheath was inserted into the right femoral artery. A pigtail catheter introduced through the left radial artery was used for aortic root angiography, which confirmed extensive valvular calcification and markedly restricted leaflet motion. Intraprocedural annular measurements demonstrated a diameter of 25.8 mm, closely corresponding to the pre-procedural CT measurement of 25.6 mm.

Balloon valvuloplasty was performed using an 18-mm balloon, corresponding to approximately 71% of the 25.6-mm annular diameter, under rapid ventricular pacing and nominal inflation pressure, approximately 4–6 atm. This undersizing strategy was designed to modify the heavily calcified valve leaflets sufficiently to facilitate prosthesis delivery while minimizing the risk of annular rupture. A smaller balloon (e.g., 15 mm) was considered insufficient to adequately modify the calcified commissures. During inflation, a pronounced balloon waist was observed. Subsequent angiography demonstrated improved leaflet opening without significant aortic regurgitation (Figs. 3, 4 and 5).

Fig. 3.

Aortic root angiography

Fig. 4.

Guidewire crossing the aortic valve

Fig. 5.

Balloon pre-dilation with an 18-mm balloon

The Prizvalve^® TAV23 prosthesis was then advanced and positioned under angiographic guidance using a 1–9 o’clock projection (Fig. 6). The deliberate oversizing strategy was employed to enhance valve-annulus apposition.

Fig. 6.

Valve frame positioning

Immediately after deployment, the patient developed profound hypotension and severe bradycardia, with blood pressure falling to 40/20 mmHg, resulting in acute circulatory collapse. Immediate angiographic and echocardiographic assessment excluded major procedural complications, including coronary obstruction, annular rupture, valve embolization, and pericardial tamponade. Electrocardiographic monitoring did not demonstrate new-onset atrioventricular block. Therefore, the most likely mechanism was rapid pacing-induced myocardial stunning, possibly compounded by a reflex vasovagal response, leading to an acute reduction in ventricular filling and forward flow. Rapid pacing was performed at 180 beats per minute for approximately 15 s during balloon inflation. Following cessation of pacing, the rhythm briefly converted to sinus tachycardia before deteriorating into severe bradycardia, with a heart rate of 30–40 bpm, consistent with myocardial stunning rather than primary conduction block.

The predefined emergency protocol was activated immediately. Chest compressions were initiated, vasopressors were administered, and pacing parameters were optimized. Spontaneous circulation was restored within several minutes. Repeat angiography confirmed stable valve positioning and satisfactory expansion without evidence of migration (Fig. 7), while bedside echocardiography excluded pericardial effusion and tamponade.

Fig. 7.

Angiography after resuscitation confirming no valve migration and good initial expansion

Following hemodynamic stabilization, the large-bore sheath was removed. Post-procedural transthoracic echocardiography demonstrated normal prosthetic valve function and a marked improvement in valve hemodynamics, with the mean transvalvular gradient decreasing from 54 mmHg preoperatively to 7 mmHg (Figs. 8 and 9).

Fig. 8.

Final angiographic assessment

Fig. 9.

Final angiographic assessment (additional view)

Post‑procedural course and follow‑up

Postoperatively, the patient developed transient delirium and a minor ischemic stroke (National Institutes of Health Stroke Scale score = 2), which resolved with neurological consultation and rehabilitation. The patient also developed pneumonia, which responded to culture-guided antibiotic therapy. At discharge, the N‑terminal pro‑B‑type natriuretic peptide concentration had decreased to 2065 pg/mL. Transthoracic echocardiography at 3 months demonstrated no evidence of paravalvular leakage, a mean transvalvular gradient of 8 mmHg, and preserved left ventricular systolic function.

Discussion

This case provides a proof-of-concept that a pre-emptive, system-based framework can render TAVR feasible even in an exceptionally high-risk patient characterized by the triad of nonagenarian age (97 years), extensive aortic valve calcification (1178 mm³), and limited physiological reserve. The successful outcome in this case was achieved through the integration of four integrated components: (1) meticulous pre-procedural imaging; (2) appropriate device selection; (3) proactive circulatory backup; and (4) structured team coordination.

Value of balloon-expandable valves in heavily calcified anatomy

A calcium volume > 1000 mm³ is a known risk factor for adverse procedural outcomes, including annular rupture, paravalvular leakage, and valve embolization [5]. In the present case, a balloon-expandable valve was selected because it offers controlled deployment. The implantation strategy incorporated deliberate oversizing, with a 23-mm valve deployed within a 25.6-mm annulus. Despite extreme calcification, this approach achieved satisfactory anchoring, avoiding paravalvular leakage and coronary obstruction. Notably, when circulatory collapse occurred immediately after valve deployment, angiography showed no valve displacement, demonstrating the anchoring stability of the balloon-expandable valve even under extreme hemodynamic fluctuations. This stability provided a favorable condition for successful resuscitation.

Analysis of the mechanism of circulatory collapse

The circulatory collapse occurring immediately after valve deployment in this case warrants careful analysis. Immediate bedside echocardiography and angiography prevented common catastrophic complications, including coronary obstruction, annular rupture, pericardial tamponade, and valve migration. In addition, continuous electrocardiographic monitoring did not demonstrate new-onset atrioventricular block. After excluding all of these more common causes, transient myocardial stunning induced by rapid ventricular pacing emerged as the most plausible explanation. In patients with severe calcific AS, the left ventricle is chronically exposed to pressure overload, resulting in myocardial hypertrophy and impaired ventricular compliance, rendering the myocardium less tolerant to rapid pacing. The approximately 15-second period of rapid pacing in this case may have induced transient but severe myocardial stunning, resulting in an acute decline in ventricular contractile function and severe bradycardia that ultimately culminated in circulatory collapse. In addition, a concomitant vasovagal response cannot be excluded. The transient transition to sinus tachycardia followed by profound bradycardia after cessation of pacing further supports myocardial stunning, rather than primary conduction block, as the predominant mechanism underlying the hemodynamic deterioration.

This observation has important clinical implications. Even in the absence of mechanical complications or conduction abnormalities, myocardial stunning alone may precipitate life-threatening hemodynamic instability during ultra-high-risk TAVR procedures. These findings underscore the importance of proactive circulatory support planning and the availability of a structured emergency response protocol when managing patients with limited physiological reserve.

Role of proactive ECMO backup

Intraprocedural circulatory collapse during TAVR is associated with high mortality. Conventional “dry” backup strategies, in which ECMO equipment remains on standby, may delay the initiation of mechanical circulatory support during a rapidly evolving emergency. While ECMO was not ultimately deployed in this case, our “wet-prepared” strategy, incorporating pre-positioned vascular access and a primed circuit, provided an immediately available rescue option. This approach was both operationally and psychologically critical, enabling the team to manage the collapse with conventional resuscitation while knowing that immediate mechanical support was available if needed.

Considerations regarding the chinese domestic balloon-expandable valve

This case also provides insight into the performance characteristics of the Prizvalve^® TAV23 system. The device’s short stent frame (18 mm) and relatively high radial force may offer theoretical advantages in patients with a common coronary ostium by reducing the risk of coronary obstruction. The deliberate oversizing strategy combined with the balloon-expandable mechanism enabled accurate anchoring despite the presence of extensive calcification, with no evidence of paravalvular leakage or coronary obstruction. The absence of valve migration following the episode of circulatory collapse, as confirmed by angiography, suggests satisfactory anchoring stability despite marked hemodynamic fluctuations. The minimally invasive transfemoral approach, together with the compact frame design, may also be particularly advantageous in very elderly patients with limited physiological reserve by minimizing procedural trauma.

However, we acknowledge a limitation of this case study, that as a single-case report, this study does not provide evidence supporting the superiority of the Prizvalve^® system over other contemporary platforms (e.g., the Edwards SAPIEN 3 or Medtronic Evolut). The device’s satisfactory performance observed in this case suggests that it may represent a viable option in selected cases involving complex anatomies. Larger comparative studies are needed to further evaluate its safety, efficacy, and long-term performance.

The occurrence of transient ischemic stroke and pneumonia further highlights the vulnerability of nonagenarian patients. Although embolic debris generation during TAVR is difficult to eliminate completely [6, 7], its clinical impact can be mitigated. This case underscores that successful treatment of extreme-risk TAVR patients requires a comprehensive multidisciplinary approach extending beyond the index procedure, including neurological monitoring and prompt management of infectious complications. Preventive strategies should include thorough risk assessment, careful intraprocedural manipulation, and consideration of cerebral embolic protection devices in appropriately selected patients [8].

Limitations

This report describes a single patient, which limits generalizability. At the time of manuscript completion, the patient’s postoperative follow-up period was limited to 3 months, representing the longest available follow-up duration. We acknowledge that the 3-month follow-up period is relatively short, which limits the assessment of long-term valve durability and functional recovery. In addition, cerebral embolic protection devices were not used. ECMO was not deployed; therefore, its efficacy as a rescue intervention remains theoretical and was not directly evaluated from this case. Furthermore, comprehensive geriatric assessment was not performed prospectively, and frailty status was evaluated retrospectively using the Clinical Frailty Scale based on available clinical records.

Despite these limitations, this case demonstrates how systematic pre-emptive strategy may help expand the feasibility of TAVR. Further studies are needed to validate this strategy and refine patient selection criteria for extreme-risk populations.

Conclusion

In an extreme-risk nonagenarian with severe calcific AS, a structured pre-procedural strategy integrating a balloon-expandable valve platform, including the Chinese domestic Prizvalve^® system, with proactive “wet-prepared” ECMO backup facilitated a successful outcome. This case underscores that systematic pre-emptive preparation is critical and offers a reproducible model for managing carefully selected high-risk TAVR cohorts.

Supplementary Information

Below is the link to the electronic supplementary material.

Abbreviations

AS

Aortic stenosis

CT

Computed tomography

ECMO

Extracorporeal membrane oxygenation

TAVR

Transcatheter aortic valve replacement

Author contributions

L. Hong and Z. Liu contributed equally to this work. L. Hong: Investigation (Lead Surgeon), Writing – Review & Editing. Z. Liu: Supervision, Conceptualization, Resources, Writing – Review & Editing. X. Zhang: Investigation (Surgical Assistance), Data Curation. C. Yao: Investigation (Surgical Assistance), Writing – Review & Editing. S. Peng: Conceptualization, Writing – Original Draft, Visualization, Project Administration. All authors have reviewed and approved the final version of the manuscript.

Funding

No external funding was received for this study.

Data availability

No datasets were generated or analysed during the current study.

Declarations

Ethics waiver/exemption statement

This retrospective educational case report, which utilizes fully anonymized clinical data, is exempt from formal ethics committee review in accordance with our institutional policy for de‑identified case reports prepared for scholarly publication. Patient confidentiality and privacy are fully protected.

Funding/support and relationships with industry

The authors have reported that they have no relationships relevant to the contents of this paper to disclose. This work was conducted as part of routine academic clinical practice and received no external funding.

Competing interests

The authors declare no competing interests.