Australia’s first V-Clamp procedure signals a new era in mitral valve treatment

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V-clamp procedure for mitral valve treatment veterinary
Releasing the V-Clamp following evidence on 2-D and 3-D TOE assessment of satisfactory reduction in mitral regurgitation 

Medical therapy has been the only option available to the many thousands of canine patients with advanced myxomatous mitral valve (MMVD) disease worldwide. Prior to the recent availability of the V-Clamp, the only surgical procedure available was open-heart mitral valve repair which carries significant risk for pets due to the need for both the heart to be transiently stopped during surgery and cardiopulmonary bypass.  

The V-Clamp is the veterinary evolution of the MitraClip used in human cardiology for patients who are not eligible for open heart repair. The MitraClip has been successfully implanted in over 150,000 people worldwide and is demonstrated to be superior to medical therapy1

The V-Clamp is a small device (approximately 8mm in length) that is implanted to clamp together the affected leaflets of the anterior and posterior mitral valves. This is known as a transcatheter edge-to-edge mitral valve repair, or a TEER procedure, and it is performed without the need for cardiopulmonary bypass of the beating heart. 

V-clamp procedure for mitral valve treatment veterinary
Sunshine 

Veterinary Cardiologists Australia (VCA) at Veterinary Specialists Services (VSS) in Brisbane recently successfully commenced implanting the V-Clamp device in patients with advanced MMVD. This article describes the story of Sunshine, Australia’s first canine V Clamp implantation (Figure 1).  

Sunshine is a 14-year-old, 5.5kg Shibu Inu dog, who underwent this revolutionary procedure to repair advanced (ACVIM Stage C) myxomatous mitral valve disease that had resulted in congestive heart failure.

Sunshine was initially diagnosed with MMVD ACVIM Stage B2 disease in Sydney, six months prior to presentation at VCA and was prescribed pimobendan 1.25 mg bid. Before moving to Brisbane, doxycycline was prescribed for a non-productive cough of three months duration, consistent with chronic airway disease.

Sunshine presented to the Animal Emergency Service at Underwood, Brisbane with clinical signs of dyspnoea, coughing and lethargy. A grade V/VI left apical pansystolic murmur was noted, inspiratory crackles noted over mid-dorsal lung fields and thoracic radiographs confirmed moderate pulmonary oedema, marked cardiomegaly and a vertebral left atrial score (VLAS) of 3. 

Therapy in pet ICU included oxygenation cage therapy, frusemide 4 mg/kg IV x 2 doses, butorphanol 0.2 mg/kg s/c and pimobendan 1.25 mg bid. Sunshine transitioned to frusemide 20 mg p/o q 12 hours and was weaned off oxygenation cage therapy. 

V-clamp procedure for mitral valve treatment veterinary
Using fluoroscopy and transoesophageal 2-D imaging to determine where to put the 14 Fr sheath into the left ventricular apex.

Sunshine was then transferred to VCA cardiology service at VSS. Echocardiography demonstrated severe mitral regurgitation, mild tricuspid regurgitation. Repeat thoracic radiographs demonstrated resolution of the pulmonary oedema. Biochemistry demonstrated marginal azotaemia (BUN 13.6 mmol/L, n: 2.5-8.9 mmol/L) and mild hypokalaemia (3.1 mmol/L, n:3.7-5.8 mmol/L). 

Sunshine was discharged and prescribed pimobendan 1.25 mg bid and frusemide 20 mg AM, 10 mg PM. One month later, Sunshine underwent a TEER procedure. 

The surgery involved placing the V-Clamp device via a transcatheter approach through the left ventricular (LV) apex. Intra-thoracic access was via a 5-6 cm length left-sided mini-thoracotomy at approximately the 7th intercostal space, adjacent to the sternum. 

The site for placement of the 14 Fr sheath into the left ventricular apex was determined by a combination of fluoroscopy and transoesophageal 2-D imaging (Figure 2). 

A purse-string suture and felt pledgets—which buttress the space beneath sutures when there is a possibility of sutures tearing through tissue, allowed safe access of the sheath into the LV chamber utilising 18g needle puncture and an 0.035 J-wire guide. 

A mesh ball-shaped device was utilised to safely traverse the mitral valve in a retrograde direction from LV to left atrium (LA). This device allowed for advancement of a 14 Fr sheath into the LA. The V-Clamp device was guided via 2-D/3-D transoesophageal (TOE) echo and fluoroscopy through the sheath to the LA and then was retracted to be positioned across the most affected leaflets of the anterior and posterior mitral valve.

The V-Clamp was released following evidence on 2-D and 3-D TOE assessment of satisfactory reduction in mitral regurgitation at the selected site (Figure 3). Following V-Clamp deployment, the mitral regurgitation was graded trivial to mild intra-operatively, with a grade I/VI murmur noted post-operatively. An acute reduction in cardiac dimensions was noted intra-operatively. A transthoracic echo assessment on Day 1 demonstrated trivial mitral valve regurgitation (Figures 4 and 5).

Within three hours of the procedure, Sunshine was ambulatory and responsive. Patients can typically be discharged the following day. Frusemide was discontinued.  

V-clamp procedure for mitral valve treatment veterinary
A transthoracic echo assessment on Day 1 demonstrating trivial mitral valve regurgitation

On echocardiographic examination 16 weeks post-surgery, Sunshine’s cardiac dimensions had returned to normal size with no mitral regurgitation present. Cardiac cachexia had resolved with a weight increase from 5.5 to 6.6 kg, with excellent activity levels.   

V-Clamp surgery is not considered experimental or high risk with the recent publication of 40 V-Clamp surgeries by Dr Chris Orton’s group at Colorado State University.2 They documented 95% procedural feasibility with no procedural deaths and an acute procedural success rate of 95%. 

This procedure did require specialised training, which was undertaken by the VCA team at a purpose-built facility in Shanghai, which trains both human and veterinary cardiologists.

Sunshine’s successful operation involved the international collaboration of six specialists/consultants and three specialist cardiologists from VCA, highlighting the collaborative effort between the device engineers (Hongyu Medical Tech), anaesthetists and the VCA/VSS team.


References:

1. Kumbani DJ, Cardiovascular Outcomes Assessment of the MitraClip Percutaneous Therapy for Heart Failure Patients with Functional Mitral regurgitation – COAPT. ACC Annual Scientific Session Online Jul 20, 2023.

2. Orton EC and Potter BM. Transcatheter Edge-to-Edge Mitral Valve Repair. 2022 ACVIM presentation.


Dr Brad Gavaghan BVSc (Hons) MANZCVS FANZCVS (Cardio), Registered Specialist Cardiologist

V-clamp procedure for mitral valve treatment veterinary
V-clamp procedure for mitral valve treatment veterinary

Dr Fiona Meyers BVSc (Hons) MANZCVS PhD DipACVIM (Cardio), Registered Specialist Cardiologist

Dr Chris Lam BA BVSc (Hons ) DipACVIM (Cardio), Registered Specialist Cardiologist

Veterinary Cardiologists Australia

Consulting at Veterinary Specialist Services

V-clamp procedure for mitral valve treatment veterinary

The Veterinary Cardiologists Australia (VCA) team began with Drs Gavaghan and Meyers, who began their specialist careers in 2000 and 2006, respectively, following completion of residencies at the UC Davis cardiology service.

Dr Lam joined the team in 2019 as a cardiology resident and went on to achieve cardiology ACVIM board certification in 2022. 

VCA consults from Veterinary Specialist Services (VSS) hospitals in Brisbane and the Gold Coast. VCA provides a highly successful interventional cardiology program with the most common procedures including patent ductus occlusion, pulmonic valve valvuloplasty, pacemaker implantation and more recently the transcatheter edge-to-edge repair (TEER) mitral valve repair procedure. 

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