Cardiac Surgery

Question 1

Coronary Artery Bypass Graft Surgery

Answer 1

• Coronary arteries are surgically revascularized
• A saphenous vein(most common), radial artery, or internal mammary artery(not long enough for posterior arteries on heart) are commonly used in CABG
• Sternum is cut in half, pull ribs apart
• Single, double, triple, quadruple

Question 2

Mechanical Valves

Answer 2

• Made from combination of metal alloys, pyrolytic carbon, Dacron, and Teflon & have rigid occluding devices
  > require anticoags to reduce incidence of thromboembolism (for the rest of life)
  > durable
  > ideal for younger pts
• If pt cannot take/be compliant with Warfarin they will clot

Question 3

Tissue Valves

Answer 3

• Constructed from animal or human cardiac tissue and have flexible occluding mechanisms
• Anticoag NOT required
• Not as durable, tend to calcify
• Good option for those tht can’t take Warfarin

Question 4

Transcatheter Valve

Answer 4

• Limited to Aortic valve AKA transcatheter aortic valve replacement (TAVR)
• The valve is a bioprosthetic valve loaded
• Post insertion: assess vascular access site for complications
  > bleeding, hematoma, limb ischemia
• Requires dual antiplatelet therapt for 3-6 mnths to prevent thromboembolism

Question 5

Postoperative Management

Answer 5

• Cardiovascular Support: support cardiac func & low output state
  > priority: adequate end organ perfusion
• Heart rate
  > may require temp pacing
  > may give meds for tachy: beta blockers (esmol) or calcium channel blockers (diltiazem)
  > amio for contraindications to beta blockers
• Preload
  > volume, low vol could be from bleeding, fluid shifts, vascular dilation
  > give crystalloid: NS or LR
  > colloids pull extravascular fluid back to vasculator
  > give blood if bleeding
• Afterload
  > sodium nitroprusside or nitroglycerin to reduce afterload, control htn, & improve CO
  > norepinephrine & phenylephrine
• Contractility
  > positive inotropic support: epi, norepi, dopamine, dobutamine

Question 6

Postoperative Management - Mechanical Complications

Answer 6

• Cardiac
  > cardiac tamponade, hematomas, vasospasm of a coronary artery graft, prosthetic valve paravalvular regurgitation, & systolic anterior motion of mitral valve
• Noncardiac
  > pneumothorax, hemothorax, & endotracheal tube malposition

Question 7

Postoperative Management - Temperature Regulation

Answer 7

• Prevent hypothermia
• Rewarm after surgery
• Hypothermia can cause depressed myocardial contractility, vasoconstriction, & ventricular dysrhythmias
  > rewarm slowly bc these comps can happen if too quick

Question 8

Postoperative Management - Control Bleeding

Answer 8

• SBP: 90-100 mmHg
  > htn can cause tension on sutures
• Sources of bleeding: mediastinal tube, incision site; assess color, quality, amnt
• Bleeding > 200ml/hr treat w/ clotting factors or meds
• Persistent mediastinal bleeding, usually > 500ml in 1 hr or 300ml/hr for 2 consecutive hrs despite normalization of clotting studies; reexploration of surgical site

Question 9

Postoperative Management - Medications & Clotting Factors used to Treat post-op Bleeding

Answer 9

• Aminocaproic acid (Amicar)
• Desmopressin acetate (DDAVP)
• Clotting factors: fresh frozen plasma, fibrinogen, platelets

Question 10

Postoperative Management - Chest Tube

Answer 10

• Maintain patency
• Assess drainage color, consistency, & amnt

Question 11

Postoperative Management - Cardiac Tamponade

Answer 11

• Life threatening
• Blood accumulates in mediastinal space
• Assessment:
  > low CO, low BP, jugular venous distention, pulsus paradoxus, muffled heart sounds, sudden cessation of chest tube drainage
• Interventions
  > emergency sternotomy in critical care unit
  > return to operating room for surgical evacuation of clot

Question 12

Postoperative Management - Pulmonary Care

Answer 12

• Mechanical ventilation
  > early extubation (by 6hrs) once the pt is hemodynamic stable, bleeding in controlled, normothermia, & can follow commands
• Supplemental oxygen after extubation
• Early ambulation (by 4hrs postop)
  > 1st dangle on side of bed, then up to chair, then walk around unit
  > teach pt abt sternal precautions when changing positions: brace w/ pillow
  > early ambulation to prevent atelectasis

Question 13

Postoperative Management - Neuro Complications

Answer 13

• Caused by: dcrd cerebral perfusion, cerebral microemboli, hypoxia, & systemic inflammatory response
• Neuro assessment
  > baseline important

Question 14

Postoperative Management - Infection

Answer 14

• Sternal wound
  > sterile dressing changes
  > very close to heart, if infected could turn into endocarditis ; vegetation on valves if infected
• Infective endocarditis
• Graft harvest site
  > leg or arm
• Hospital-acquired infections

Question 15

Postoperative Management - Acute Kidney Injury

Answer 15

• Diuresis given for fluid retention
  > loop
• Monitor urine output & serum creatinine lvls
  > 0.7-1.2

Question 16

Postoperative Management - Resuscitation of Pts who Arrest After Surgery

Answer 16

• DO NOT initiate chest compressions
• VF or pulseless VT
  > 3 sequential attempts at defibrillation before external cardiac massage
• Asystole or extreme brady
  > attempt to pace if wires are available before external cardiac massage
• Pulseless electrical activity
  > any rhythm, but no pulse
  > go thru Hs & Ts
  > quickly assess for & treat reversible
  > if treatable cause not identified; emergency reseternotomy
• The importance of early emergency resternotomy (w/in 5 mins) is a major focus of the recommendations