Aortic cusp catheter ablation of premature ventricular contractions

Premature ventricular contractions originating from the aortic cusps represent a distinct subset of idiopathic ventricular arrhythmias that often prove resistant to standard medical therapy. The aortic root sits just inferior to the ventricular outflow tracts, and within its three sinuses of Valsalva, fibromuscular extensions of ventricular myocardium can serve as the source of ectopic beats. Recognition of this anatomic origin is critical because surface electrocardiogram features can mimic outflow tract patterns from the right ventricular side, leading to ineffective ablation if the operator targets the wrong chamber.

In Australian electrophysiology labs, patients with symptomatic PVCs often present after months of palpitations, fatigue, or what they describe as a "skipped beat" sensation that disrupts their work, exercise, or even a quiet arvo at home. Many have already been trialled on beta-blockers or calcium-channel blockers through their general practitioner, and some have been commenced on antiarrhythmic agents funded through the Pharmaceutical Benefits Scheme. When symptoms persist or the PVC burden exceeds 10–15% on ambulatory monitoring, referral to a tertiary centre for catheter ablation is a reasonable next step.

Aortic cusp ablation carries a unique procedural flavour compared with right ventricular outflow tract work, demanding careful attention to the coronary ostia and the conduction tissue nearby. Operators at high-volume units such as Royal Melbourne Hospital, Westmead, and the Royal Brisbane and Women's Hospital have refined an approach that combines electroanatomic mapping with intracardiac echocardiography, fluoroscopy, and coronary angiography. The remainder of this review walks through the anatomic basis, mapping strategy, ablation technique, and Australian-specific outcomes that inform modern practice.

Anatomic and electrophysiologic basis

The aortic root contains three sinuses: the left coronary cusp, the right coronary cusp, and the non-coronary cusp. Each cusp cradles the corresponding coronary ostium, and the left main and right coronary arteries arise within millimetres of the targeted ablation sites. Myocardial sleeves extend into the bases of these cusps, particularly on the left and right sides, and these remnants are the usual culprits behind ectopic activity. Histologically, the tissue resembles working ventricular myocardium but transitions abruptly into the fibrous aortic wall, a feature that explains the often sharp local electrograms recorded at successful ablation sites.

The non-coronary cusp generally lacks ventricular myocardium and is rarely a culprit focus, though it occasionally harbours His-bundle-related activity that can be useful as an anatomic landmark. Because of this asymmetric distribution, most operators centre their attention on the left and right coronary cusps, often using a reversed S-curve catheter approach via retrograde aortic access. Understanding which cusp is most likely responsible based on surface ECG morphology—particularly the QRS transition and the inferior axis—remains the first filter before any catheter is advanced.

A useful clinical pearl is that aortic cusp sites typically sit just below the plane of the pulmonary valve when viewed in the oblique projection. Where there is doubt about whether the focus truly originates in the cusp versus the adjacent LV summit, pacing manoeuvres, near-field recordings, and detailed activation mapping help clarify the picture.

Pre-procedural ECG interpretation and patient selection

Surface 12-lead ECG during ectopic beats gives surprisingly accurate clues. Aortic cusp PVCs typically show an inferior axis with a left bundle branch block pattern, but the precordial transition often occurs at or before V2—earlier than typical right ventricular outflow tract origins. A taller R wave in lead I and a wider, more notched R in V1 and V2 favours a left coronary cusp origin, while a transition at V3 with a less dominant R in V1 may suggest a right coronary cusp source. Lead aVL and aVR ratios, along with the morphology in the inferior leads, further refine the prediction.

Patients considered for ablation in Australia are usually those with a high symptomatic PVC burden, suspected PVC-mediated cardiomyopathy, or recurrent PVC-triggered ventricular fibrillation. Before listing, a careful work-up includes transthoracic echocardiography to assess left ventricular function, ambulatory monitoring to quantify burden, and exclusion of ischaemia where appropriate. Those living in regional areas—from the wheatbelt of Western Australia to the far north of Queensland—often need help coordinating travel to a metropolitan centre, and telehealth consultations through Medicare-funded specialist services help bridge that gap in the lead-up to admission.

Selection also includes a careful medication review, since concurrent use of class IC agents or amiodarone can alter PVC morphology and confound mapping. Patients on long-term amiodarone may require a washout period of several weeks to ensure a reliable procedural target.

Intracardiac mapping and coronary safety

Once in the lab, mapping begins with construction of an electroanatomic shell of the aortic root using either CARTO or EnSite systems, fused with pre-procedural CT angiography to visualise the coronary ostia. A retrograde aortic approach is standard, and a multipolar catheter is often placed in the His region for reference. Intracardiac echocardiography provides real-time visualisation of catheter tip position relative to the cusps and coronary arteries, dramatically reducing the risk of inadvertent arterial injury.

Coronary angiography is performed before any energy delivery, with the left main and right coronary arteries profiled in multiple projections. A safe distance of at least 5 mm between the ablation catheter tip and a coronary ostium is the working rule, although some operators accept closer distances with very low-power titration. Where mapping reveals an ideal site that sits too close to a coronary vessel, ablation is either deferred or pursued with cryotherapy, which carries a different risk profile and can be considered when radiofrequency energy is felt unsafe.

Where mapping is hampered by infrequent ectopy, catecholamine provocation with isoprenaline or programmed stimulation may be required to expose the culprit. In cases of truly quiescent targets, substrate modification based on low-voltage signals can guide ablation, although evidence for this approach in the aortic cusps is less developed than for scar-based ventricular tachycardia.

Ablation strategy and endpoint

Radiofrequency energy remains the workhorse for aortic cusp ablation. Typical settings begin at 20–25 W with a target temperature of 43 °C, escalating cautiously if no effect is seen within 10 seconds. Irrigation flow is maintained at 17–30 mL per minute to cool the catheter tip and reduce the risk of char formation near the coronary ostia. An impedance drop of 8–10 ohms and the appearance of accelerated or diminished ectopic beats often herald imminent success, after which a 60–90 second consolidation burn is delivered.

Procedural endpoints include complete elimination of the targeted PVC morphology both spontaneously and under isoprenaline or aminophylline infusion. Pace mapping from the successful site should reproduce a near-identical 12-lead match (≥11 of 12 leads), confirming that the recorded site is genuinely the source rather than a bystander. When endpoints cannot be achieved due to proximity to a coronary ostium or the His bundle, a shared decision with the patient—often conducted in plain language during the pre-admission clinic—guides whether to accept partial success or defer further attempts.

Post-ablation observation in a monitored bed overnight is standard, with telemetry continued until the morning review. Repeat coronary angiography is not routine unless there is clinical suspicion of vessel injury, and most patients are discharged within 24 hours once ambulatory and haemodynamically stable.

Outcomes, complications, and Australian practice patterns

Acute success rates for aortic cusp PVC ablation in contemporary series sit between 85% and 95%, with recurrence rates of 5–10% over the following year. Complications are uncommon but clinically significant when they occur: coronary artery spasm or stenosis, aortic regurgitation from leaflet injury, stroke, and rarely, complete heart block when targeting sites near the membranous septum. Meticulous imaging, low-power starts, and routine coronary angiography have substantially reduced these risks over the past decade.

Australian centres report outcomes broadly consistent with international data, although the small population and selective referral patterns produce modest series. For patients with PVC-triggered polymorphic ventricular arrhythmias, ablation often forms part of a broader strategy that includes defibrillator therapy and avoidance of triggers; the practical lessons of one comprehensive follow-up review of idiopathic VF workup echo the importance of treating each case as part of a longitudinal pathway rather than a single procedural event. Post-procedure care typically includes a 24-hour Holter monitor, echocardiography before discharge, and review in the arrhythmia clinic at three months, after which many patients return to their general practitioner with a clear plan.

Patient-reported outcomes are increasingly captured in Australian registries and quality-of-life surveys, allowing meaningful comparison between centres and helping patients make informed choices. Recurrence detection in the first year remains a particular focus, since early re-intervention may offer better long-term arrhythmia control than waiting for symptom-driven presentation.

Future directions and integrated care

Newer mapping technologies—including high-density multipolar catheters and omnipolar signal processing—promise faster identification of culprit sites, particularly when PVCs are infrequent. Pulsed-field ablation, already reshaping atrial fibrillation workflows, is being trialled for ventricular arrhythmia applications, with early data suggesting a favourable safety profile near coronary ostia. Training pathways will need to adapt as these tools become available across Australian teaching hospitals.

Integrated care models are equally important. Patients benefit from a clear chain of support that begins with their GP, extends through regional cardiology outreach, and finishes with the procedural team. Embedding structured follow-up—Holter monitoring, echocardiography, and timely medication review—helps catch recurrences early. Allied health input and cardiac rehabilitation referrals form an important part of recovery for those whose PVCs have dominated daily life for months or years.

Training the next generation of aortic cusp operators requires curricula that pair didactics with hands-on exposure to high-volume cases. Fellowship programmes at Australia's tertiary centres typically offer dedicated ventricular arrhythmia rotations, and society-sponsored workshops provide additional exposure for early-career electrophysiologists. Standardised proctoring for pulsed-field platforms will be essential as the technology diffuses into routine care.

The journal welcomes original research, case reports, review submissions, and themed collection ideas from the Asia-Pacific electrophysiology community. For manuscript enquiries, reviewer applications, or collaboration suggestions, please reach out through the journal's contact page.