Surgeries of cardiovascular system in dogs.pptx

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1. SURGERIES OF CARDIOVASCULAR SYSTEM SUBMITTED BY DR MEENU P M M.V.Sc SCHOLAR DEPARTMENT OF VETERINARY SURGERY AND RADIOLOGY SUBMITTED TO DR R V RAULKAR ASSISTANT PROFESSOR DEPARTMENT OF VETERINARY SUGERY AND RADIOLOGY MAHARASHTRA ANIMAL AND FISHERIES SCIENCES UNIVERSITY, NAGPUR POSGRADUATE INSTITUTE OF VETERINARY AND ANIMAL SCIENCES,AKOLA DEPARTMENT OF VETERINARY SURGERY AND RADIOLOGY

2. APPROACHES TO CARDIAC SURGERY OPEN HEART SURGERY Deals with structures inside the heart CLOSED HEART SURGERY Deals with the structures outside the heart

3. IMPORTANT TERMS VENOUS INFLOW OCCLUSION Inflow occlusion is a technique used for open heart surgery in which all venous flow to the heart is temporarily interrupted. Because inflow occlusion results in complete circulatory arrest, it allows limited time to perform cardiac procedures. Ideally, circulatory arrest in a normothermic patient should be less than 2 minutes, but it can be extended to 4 minutes if necessary

4. Inflow occlusion from a right thoracotomy is readily accomplished by passing tape or heavy suture tourniquets around the caudal vena cava and around the common drainage of the azygous vein and cranial vena cava outside the pericardium. Inflow occlusion is performed from a left thoracotomy by passing separate tourniquets around the cranial and caudal venae cavae and azygous vein. Access to the cranial vena cava is gained by opening the cranial mediastinum. Access to the caudal vena cava is gained by opening the caudal mediastinum and plica vena cava. The azygous vein is accessed by dissecting through the mediastinum dorsal to the esophagus and aorta

5. CARDIOPULMONARY BYPASS Cardiopulmonary bypass is a procedure whereby an extracorporal system provides flow of oxygenated blood to the patient. Cardiopulmonary bypass provides for a motionless and bloodless operative field and time to perform more complex cardiac repairs Cannulation for cardiopulmonary bypass can be accomplished from a right or left thoracotomy or median sternotomy

6. SUTURE MATERIALS Polypropylene ( Prolene , Surgipro ) and braided polyester ( Ticron , Mersilene ) suture are the standard sutures used for cardiovascular procedures. The sizes most commonly used are 3-0, 4-0, and 5-0, although smaller sizes may be needed for vascular anastomoses. Sutures should be available with swaged-on taper-point cardiovascular needles in a variety of sizes. Some procedures require that the suture be double armed (i.e., with needles at both ends). Teflon pledgets are useful for buttressing mattress sutures in ventricular myocardium or great vessels

7. SPECIAL INSTRUMENTS Although most of the basic instruments required for general surgery can be used for cardiac surgery ; few specialized instruments are desirable for thoracic surgery Finochietto retractors Tangential ( Satinsky ) vascular clamps

8. Potts scissors, DeBakey tissue forceps, Julian thoracic artery forceps, Mixter forceps

9. Right lateral aspect of the canine heart SURGICAL ANATOMY

10. Left lateral aspect of the canine heart

11. In general, most patients are premedicated with an opioid (e.g., hydromorphone, oxymorphone, methadone) and a benzodiazepine (e.g., midazolam, diazepam). Acepromazine avoided ( prolonged hypotension ) Similarly, alpha-2 agonists cause significant cardiovascular depression and should be avoided. An anticholinergic drug (e.g., glycopyrrolate, atropine) is administered to animals with bradycardia. Patients are preoxygenated, and anaesthesia is induced with drugs such as fentanyl or etomidate, which demonstrate a wide cardiovascular safety margin. Anaesthesia is maintained with balanced protocols consisting of combinations of an inhalant, such as isoflurane or sevoflurane in oxygen; an opioid, such as fentanyl; a benzodiazepine (e.g., midazolam); and a neuromuscular blocking agent, such as atracurium besylate. Monitoring includes electrocardiography, direct arterial blood pressure, end-tidal CO 2 , pulse oximetry, body temperature, central venous pressure, arterial blood gases, electrolytes, packed cell volume, total protein, and lactate, depending on the degree of cardiac dysfunction present. Positive-pressure ventilation is maintained during surgery with or without positive end-expiratory pressure (PEEP). ANAESTHESIA IN CV PATIENTS

12. MITRAL REGURGITATION Most common form of acquired heart disease in dogs. Commonly occurs as the result of myxomatous degeneration of the valve

13.   T wenty times more prevalent in the Cavalier King Charles spaniel than other breeds

14. CLINICAL PRESENTATION Many animals are asymptomatic Affected animals may have a history of exercise intolerance, coughing, and/or shortness of breath. A murmur associated with MR may be picked up on physical examination in an asymptomatic animal HISTORY

15. STAGES

16. An  echocardiogram  (ultrasound of the heart) is the most commonly recommended diagnostic test. DIAGNOSIS

17. SURGICAL TREATMENT Surgical treatment of mitral regurgitation is routine in human medicine and most commonly consists of mitral valve repair. Successful mitral valve repair has also been accomplished in dogs; currently, however, the only successful program is in Japan and is expensive (the  Mighty Hearts Project  provides more information). Replacement of the mitral valve with a prosthetic valve is almost uniformly unsuccessful.

18. For mitral valve replacement, a mechanical or bioprosthetic heart valve is typically used. Disadvantages of these valves are that the animal must be placed on lifelong anticoagulation therapy, and early pannus formation and calcification occur with bioprosthetic valves (bioprosthetic). Techniques for mitral valve repair that use cardiopulmonary bypass are probably safer than those that do not, particularly in animals with severe heart failure. However, bypass procedures are expensive and are not readily available in veterinary medicine SURGICAL TREATMENT(CONTD)

19. MITRAL VALVE ANNULOPLASTY TECHNIQUE

20. Dog with severe mitral regurgitation before and after mitral valve repair. Prior to surgery, the dog was thin, had a poor hair coat and abdominal distension (A). Six months after surgery, the dog had regained the condition(B)

21. PATENT DUCTUS ARTERIOSUS The ductus arteriosus is a fetal vessel that connects the main pulmonary artery and the descending aorta. During development, it shunts blood away from collapsed fetal lungs. Normally, it closes shortly after birth during the transition from fetal to extrauterine life. Continued patency of the ductus arteriosus for longer than a few days after birth is called patent ductus arteriosus (PDA)

22. HISTORY Young animals mostly asymptomatic/mild exercise intolerance Cough / shortness of breath due to pulmonary edema REVERSE PDA “Differential” cyanosis is typically present (i.e., cyanosis is most apparent in the caudal mucous membranes),

23. Physical Examination Findings The most prominent physical finding associated with PDA is a characteristic continuous (machinery) murmur heard best at the high left heart base or left axillary region. DOGS WITH PDA SHOULD NOT BE USED FOR BREEDING, REGARDLESS OF THE BREED.

24. Angiographic studies determine the ductal morphology and the minimal ductal diameter (MDD) of the PDA ANGIOGRAPHY

25. ECHOCARDIOGRAPHY Left atrial enlargement, left ventricular dilation, pulmonary artery dilation, increased transaortic and transmitral flow velocities, and a characteristic reverse turbulent Doppler flow pattern in the pulmonary artery.

26. SURGICAL TREATMENT Amplatzer Vascular Plugs and the Amplatzer Canine Duct Occluder are self-expanding multilayered Nitinol devices and vascular plugs that have been shown to effectively occlude a wide range of ductal shapes and sizes with better outcomes over surgical ligation and other methods of transcatheter occlusion Intravascular coils, vascular plugs, and duct occluders are now used routinely for closure of patent ductus arteriosus

27. AMPLATZ CANINE DUCT OCCLUDERS (ACDOS) Amplatz Canine Duct Occluders (ACDOs) were developed specifically for the purpose of minimally invasive PDA occlusion in dogs A small incision is made on the inside of the leg over the femoral artery.  A catheter is then placed inside the femoral artery and it is directed by fluoroscopy through the blood vessels and into the PDA. Once the correct positioning is confirmed by angiography (contrast injection into the blood vessel , the ACDO device is deployed into the PDA to completely occlude blood flow through this extra blood vessel

28. A similar device, the  Amplatzer Vascular Plug2 (AVP),  has a smaller delivery sheath than does the ACDO, and therefore is used more often on smaller dogs. Embolization coil,  a catheter containing a spring coil (for small PDAs), such as the  Flipper    is a third option but is less used.

29. Jackson-Henderson technique Jackson-Henderson technique was first described in 1979 as a novel surgical technique for the ligation of PDA. This technique was used for PDA correction in several studies. One of the main disadvantages of the Jackson-Henderson technique is the potential residual shunting that has been described in previous reports due to soft tissue inclusion in the ligatures

30. SURGICAL LIGATION During patent ductus arteriosus (PDA) ligation, elevate and retract the left vagus nerve to expose the ductus arteriosus. The left recurrent laryngeal nerve may be seen as it separates from the vagus nerve and courses caudally around the ductus arteriosus. Ligate the patent ductus arteriosus (PDA) by passing two ligatures around the ductus arteriosus. Tie the ligatures separately. Isolate the craniomedial aspect of the ductus arteriosus by bluntly dissecting with an angled forceps. The forceps should be directed at a 45-degree angle from the transverse plane.

31. POSTOPERATIVE CARE & COMPLICATION Postoperative pain should be treated with systemic opioids and local anesthetic techniques. Young animals should be fed as soon as they are fully recovered from surgery. The most serious complication of PDA ligation is rupture Pulmonary embolization of transcatheter coils or other devices used to embolize PDA occasionally occurs Infection of cardiovascular implants is an uncommon but serious complication a

32. AORTIC STENOSIS Aortic stenosis (AS) is a congenital narrowing of the aortic valve, aorta, or left ventricular outflow tract. The stenosis may be supravalvular, valvular, or sub valvular Sub valvular AS (SAS) accounts for more than 90% of canine cases The disease is mildest when the puppy is really young and gets worse over the first 6 to 12 months of life.

33. CLINICAL SIGNS In many cases, affected dogs do not show any signs. Advanced cases may present with exercise intolerance, syncope, or abdominal distention from ascites Systolic ejection murmur heard best at the left heart base is the predominant clinical finding

34. DIAGNOSTIC IMAGING Chest radiograph of a puppy with SAS. The bulge of the aortic valve is conspicuous.  Thoracic radiographs may reveal a normal cardiac silhouette / mild left ventricular and left atrial enlargement. Enlargement of the ascending aorta frequently is evident.

35. 4-month-old Irish setter with severe aortic stenosis. A post-stenotic dilation of aortic arch is seen 

36. ECHOCARDIOGRAPHY A color-Doppler flow image of a Sphynx cat with fixed and dynamic subaortic stenosis and concentric hypertrophy of the left ventricle (LV) with concurrent mitral regurgitation (MR) Subaortic fibrous hyperechogenic tissue protruding into the LVOT is seen in the right parasternal view in a young Newfoundland with severe subaortic stenosis. Definitive diagnosis of SAS is obtained by echocardiography

37. Subaortic stenosis is a genetic disease. Because inheritance is not simple, dogs with mild disease may produce puppies with severe disease. A tunnel-like subaortic stenosis (upper 2 arrows) and a fibrous subaortic ring below the aortic valve is seen No dog with subaortic stenosis of any degree should be bred.

38. Gross pathologic specimen from a dog with severe subaortic stenosis. A subvalvular fibrous ring (lower arrow) below the aortic valve and a thickened valve above the fibrous ring of tissue can be seen. Ao—aorta, LV—left ventricle, LA—left atrium, and MV—mitral valve. https://www.intechopen.com/chapters/66972 Domanjko P et al., (2019). Aortic Stenosis in Dogs and Cats: Past, Present and Future. IntechOpen . doi : 10.5772/intechopen.84891 C lose-up of a closed fibrous subaortic tissue that encircles the left ventricular outflow tract just below the entrance to the aorta.

39. MEDICAL MANAGEMENT β-Adrenergic blockade therapy with propranolol or atenolol decreasing myocardial oxygen requirements ,suppressing ventricular arrhythmias during exercise.

40. SURGICAL MANAGEMENT Surgical options for dogs with SAS include valve dilation and open resection.

41. PS is the third most common congenital heart defect in dogs after PDA and SAS; it is uncommon in cats Pulmonic stenosis (PS) is a congenital narrowing of the pulmonic valve, pulmonary artery, or right ventricular outflow tract Synonyms include pulmonic valve dysplasia and right ventricular outflow tract obstruction. PULMONIC STENOSIS

42. CLINICAL PRESENTATION SIGNALMENT English Bulldogs, Scottish Terriers, Wirehaired Fox Terriers, Beagles, Miniature Schnauzers, Cocker Spaniels, Samoyeds, and Mastiffs are at increased risk for developing PS. HISTORY Young animals with PS are often asymptomatic. Advanced cases may present with exercise intolerance, syncope, or abdominal distention from ascites. PHYSICAL EXAMINATION FINDINGS The predominant physical finding is a systolic ejection murmur heard best at the left heart base DIAGNOSIS

43. DIAGNOSTIC IMAGING Diagnosis of PS can be confirmed by echocardiography. (A) Type A valvular pulmonic stenosis is characterized by mild thickening of the valve, fusion of the leaflets with decreased systolic excursion, and normal annulus diameter. (B) Type B valvular pulmonic stenosis is characterized by moderate to severe valve thickening, variable leaflet hypoplasia, minimal leaflet fusion, and narrowing of the pulmonary valve annulus.

44. SURGICAL MANAGEMENT Surgical options for correction of PS include valve dilation and patch-graft valvuloplasty. With the advent of balloon valvuloplasty, operative valve dilation is seldom indicated. When to Perform Balloon Valvuloplasty When considering whether to recommend BV for VPS, four aspects of the patient should be considered: S everity of PS T ype of stenosis C oncurrent cardiac defects C oncurrent systemic disease .

45. EQUIPMENTS INTRODUCERS GUIDE WIRES CATHETERS

46. (A) A cut-down over the jugular vein has been performed and the jugular vein dissected free. (B) Rumel tourniquets have been placed around the jugular vein at the cranial and caudal extent of the dissection. (C) A #11 blade is used to make the vascular incision parallel to the long axis of the vessel. A vein lifter can be placed within the incision once made to assist in placing the guidewire. (D) The vein lifter assists in holding the incision open as the introducer guidewire is passed into the vein lumen.

47. E) The introducer with the vein dilator in place is passed down the guidewire and into the vessel lumen. (F) As the vein dilator expands the vessel the introducer shaft is passed into the vessel lumen. Notice that the caudal Rumel tourniquet has been loosened to allow passage of the introducer. (G) The introducer, vein dilator, and introducer guidewire are in place. Because the vein dilator fills the lumen of the introducer, no blood is seen in the side port. (H) The vein dilator and guidewire have been removed. If the introducer is properly placed, negative pressure on the sideport will draw blood into the introducer. Notice that the caudal Rumel tourniquet has been tightened around the introducer shaft to prevent hemorrhage.

48. Fluoroscopic pictures of angiogram and balloon valvuloplasty.

49. VENTRICULAR SEPTAL DEFECT Ventricular septal defect (VSD) is a congenital defect that results from failure or incomplete development of the membranous or muscular interventricular septum Ventricular septal defect (VSD) is a common congenital disease in cats and also occurs in dogs. VSD occurs due to incomplete formation of the interventricular septum.

50. Ventricular septal defects are  most commonly located in the perimembranous portion of the septum

51. CLINICAL PRESENTATION Young animals with VSD often are asymptomatic at first presentation. Animals with large VSD may have signs of left-sided CHF (i.e., cough and shortness of breath). The most prominent physical finding associated with VSD is a systolic murmur with the point of maximal intensity at the right sternum.

52. THORACIC RADIOGRAPHY Thoracic radiographs reveal varying degrees of left or biventricular enlargement depending on the size and position of the defect Cat VSD DV Cat VSD Right Lateral VSD with Amplatz Occlusion Right Lateral

53. ECHOCARDIOGRAPHY VSD ECHOCARDIOGRAPHY VSD IN DOG –MULTI DETECTOR COMPUTED TOMOGRAPHY

54. SURGICAL TREATMENT Surgical intervention should be considered for hemodynamically significant VSD. Pulmonary artery banding has been used successfully to palliate dogs and cats with VSD. The goal of pulmonary artery banding is to increase right ventricular systolic pressure, thereby decreasing shunt flow.

55. PULMONARY ARTERY BANDING

56. TETRALOGY OF FALLOT Pulmonic stenosis VSD Dextropositioned overriding aorta Right ventricular hypertrophy Tetralogy of Fallot is a complex congenital heart defect that consists of

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