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The treatment of choice for severe pulmonic stenosis is reduction of the stenosis.
- Surgical correction
- Objective of correction is not to completely relieve the obstruction but to substantively increase the size of the orifice.
- Several procedures have been described
- Patch graft procedure
- Valvulotomy via the MPA
- Valvuloplasty with a closed knife and/or valve dilator introduced into the RVOT
- Implantation of a valved or non-valved conduit detouring the stenosis (from the RVOT to the MPA)
- Balloon valvuloplasty
- Single balloon procedure
- Introduced via the jugular vein or femoral vein
- Double balloon procedure
- One introduced via each femoral vein
- Single balloon procedure
- Compare and contrast these procedures:
- Cost: almost identical
- Morbidity: surgical correction involves a thoracotomy with the pain inherent in that procedure and the potential for hemothorax, hydrothorax, pyothorax, and pneumothorax. With balloon valvuloplasty severe arrhythmias can develop and it is possible for ventricular fibrillation and death to occur. Arrhythmic death can occur with either procedure. In children balloon valvuloplasty is an outpatient procedure and the preferred method of treatment.
- Mortality: surgical mortality is not reported, however the authors would expect comparable mortality with both procedures.
- Complications: with surgery include all those encountered with a thoracotomy. Balloon valvuloplasty is associated at times with trauma to the tricuspid valve. English bulldogs and boxers have been described to possess, at times, an aberrant single right coronary artery (type R2A) which gives rise to the left coronary that encircles the base of the MPA at the level of the pulmonic annulus. Patch Graft surgery and balloon dilation have both had fatal results if this anomaly is present at the time of correction of the pulmonic stenosis.
- Efficacy of correction: The authors have not been impressed with the Patch Graft technique. As the surgical experience with the other methods is limited it is not possible to comment on efficacy. Although data is limited it appears that dogs that have undergone successful balloon valvuloplasty are at least 2 times more likely to reach 2 years of age compared with untreated dogs.
- Control dysrhythmias
- as for aortic stenosis
- Control signs of right heart failure
- diuretics – furosemide (these should be used sparingly)
- Infundibular hypertrophy may be controlled with beta blocker therapy. This remains unsubstantiated.
- Furosemide (Lasix):
- dog: 2-4 mg/kg BID-TID (IV, IM, SQ, PO); 2-8 mg/kg q 1 hr (IV) in severe pulmonary edema
- cat: 1-2 mg/kg BID-TID (PO, IM, IV) do not exceed 2 mg/kg (IV)
- Propranolol:
- dog: 0.21-1.0 mg/kg TID (PO); 0.04-0.06 mg/kg (IV) slowly
- cat: 0.21-1.0 mg/kg BID-TID (PO); 0.04 mg/kg (IV) slowly
- Metoprolol:
- dog: 0.5-1 mg/kg TID (PO)
- cat: 2-15 mg TID (PO)
- Atenolol:
- dog: 5-12.5 mg SID (PO)
- cat: 5-12.5 mg SID-BID (PO)