Purse-String surgery was attempted from 1962-1994 in 15 dogs, 4 months to 12 years old, with severe mitral regurgitation and refractory congestive heart failure. Varying techniques and PSS designs were used. Twelve dogs had severe chronic mitral valve disease, two dogs had primary annular dilation presumably due to cardiomyopathy and the 4 months-old dog had hypoplastic mitral leaflets. Three of the smallest dogs (6-8 kg) died of iatrogenic left atrial hemorrhage before a PSS could be put in place and before technical modifications were developed to overcome size limitations. Other operative deaths were caused by coronary sinus tears in 2 dogs and left main coronary artery perforation in 1 dog. Postoperative deaths within 4 days were caused by left circumflex CA entrapment in 2 dogs and LCx compression by the PSS knot in 1 dog. The 4 mo-old dog with hypoplastic mitral leaflets was euthanized one hour after surgery because hemodynamic values were not improved by the operation. Two other dogs surviving surgery were euthanized within 4 days because of intractable respiratory failure that was evident preoperatively. Three long term survivors were euthanized after 6-26 months for non-cardiac reasons without recurrent congestive heart failure. (Buchanan JW and Sammarco CD. Veterinary Surgery 27:182-195,1998.)

Preoperative radiograph from a 4 month-old German Shepherd with mitral regurgitation and marked left atrial enlargement. PSS surgery was performed 4 months later. 

Guerneeysurvey4-mo

Guerney-p.o-angio-LV--10--m A left ventricular injection angiocardiogram 6 months after PSS surgery shows no evidence of mitral regurgitation although mild left atrial enlargement is still present.

Guerney-p.o-angio-Ao--10--m An aortic root injection angiocardiogram shows mild left circumflex coronary artery tortuosity but no evidence of obstruction. The central marginal CA (M) and subsinuosal CA (arrow) branches are patent.

An eleven year-old, 30kg, mixed breed dog was admitted for surgery because of an abdominal mass and ascites requiring weekly abdominocentesis for 4 months. He had a grade 5/6 systolic murmur of mitral regurgitation, left apical protodiastolic gallop, atrial fibrillation, frequent ventricular premature beats and moderate ascites. Thoracic radiographs revealed interstitial edema, pleural effusion and left sided cardiomegaly (vertebral heart size = 13.1v). Echocardiography confirmed severe mitral regurgitation and enlarged left heart chambers with a 34% left ventricular shortening fraction. The LA:Ao ratio was 2.6. The dog also had an abdominal mass 10cm in diameter, hypothyroidism and laryngeal hemiplegia. One month later after some improvement with medical therapy, purse-string surgery and lateralization of an arytenoid cartilage were performed. Three weeks later a splenectomy was done. The spleen contained a 3.2 kg organized hematoma.

Dorworth pre op

Radiographs one week after surgery show PSS position around the mitral annulus. A urethane coated endocardial pacemaker lead containing a helical wire was used to make the PSS and yielded a larger, more radiopaque PSS than the barium sulfate thread in subsequent cases.

Dorworth po lat

Dorworth po dv

Two-dimensional echocardiogram, right parasternal long axis view demonstrating purse-string diameter (arrowheads) and its position next to the base of the mitral valve leaflets 1 month after surgery.

postecho2

From 1 to 18 months after surgery, the dog was much improved. He was more exercise tolerant, had gained weight to 36kg and had no ascites. He still had mitral regurgitation and atrial fibrillation but the heart size was smaller. He was medicated with usual cardiac drugs and never again had signs of congestive heart failure. He was euthanized 26 months after surgery because of intractable diarrhea, 10kg weight loss and coughing due to bronchial compression by his large left atrium (confirmed radiographically) and probable laryngeal dysfunction.

Dorworth 1 yr p.o

Vertebral heart size decreased significantly after PSS surgery for at least 18 months.

graph2vhs

Necropsy photographs of the open right atria of three PSS dogs 6-26 months after surgery. At 6 months, the Silastic layer was almost completely covered by fibrous tissue. In the 18 month dog, there was no encapsulation but a thrombus was present on the PSS at its entrance and exit in the right atrium. In the 26 month dog, a urethane coated endocardial pacemaker lead was used for the PSS. It was completely encapsulated by white fibrous tissue in the right atrium.

PSS-3-dogs-RA

Hemodynamic effects of purse-string annuloplasty were studied in five experimental dogs three weeks after induced, significant mitral regurgitation. The mitral regurgitant fraction was reduced immediately after purse-string annuloplasty (black bars). A greater reduction fraction was recorded in three of the dogs seven days after surgery (white bars).

rfgraph

From Kerstetter KK, Sackman JE, Buchanan JW, et al. Vet Surg 27:216-223,1998)

Case Selection for Purse-String Surgery

• Severe mitral regurgitation
• Significant annular dilation
• Refractory congestive heart failure
• Reasonably good ventricular function
• Presurgical control of pulmonary edema
• Realistic owner expectations
• Currently a "last ditch" effort