PETROS (Percutaneous Transcatheter Release Of Stuck mechanical valve leaflet)

PETROS stands for Percutaneous Transcatheter Release Of Stuck mechanical leaflet (or mechanical valve). It is an emerging, bail-out structural heart intervention used to mechanically mobilize jammed prosthetic valve leaflets caused by acute thrombosis or pannus formation.

The Clinical Rationale

The standard Class I recommendation for obstructive mechanical valve thrombosis is emergency surgery or an ultra-slow infusion of fibrinolytics (like alteplase). However, management gets complicated when a patient presents with a high STS score, absolute contraindications to thrombolysis, or when fibrinolysis simply fails.

PETROS offers a percutaneous alternative for these exact scenarios, potentially sparing the patient from a high-risk redo sternotomy. Given the shift toward “lifetime management” strategies for heart valves rather than binary surgical choices, it is becoming a fascinating tool to keep in the structural intervention arsenal.

The Procedure

The technique relies on applying direct mechanical force to free the hinge mechanism.

1. Cerebral Embolic Protection (CEP): Because mobilizing the thrombus carries a massive stroke risk, deploying CEP is a mandatory first step.
2. Wire Crossing: A stiff guidewire (often a 0.014″ coronary wire) is carefully threaded through the valve orifice, typically between the stuck leaflet and the surgical ring.
3. Balloon Dilatation: Sequential balloon inflations—starting with small non-compliant coronary balloons (e.g., 1.5 mm to 5.0 mm) and scaling up to peripheral balloons if necessary—are used to pry the leaflet open and restore normal closing and opening angles.

Evidence and Outcomes

While isolated case reports have appeared over the last few years, the most substantial recent data comes out of the Madras Medical Mission in Chennai. A 2024 study published in Circulation: Cardiovascular Interventions tracked 24 patients who underwent PETROS with CEP for stuck mitral mechanical valves.

• Efficacy: Technical success was high, achieved in ~92% of the procedures with a rapid drop in transvalvular gradients.
• Risks: Embolization remains the biggest threat, even with CEP (since the vertebral arteries are often unprotected). The Chennai study reported a 4% stroke rate and a ~17% recurrence rate of the stuck valve within the mid-term follow-up period.
• Post-Procedure: If a leaflet becomes re-stuck, repeat PETROS or a return to fibrinolysis are the primary management options.

A demo of the procedure with fluoroscopy clips is available on X account of @DrRajeshMAMC.