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CPBM Also known as a heart-lung machine. It is a device that does the work of the heart & lungs when theheart is stopped for a surgical procedure, or for other reasons. Most patients are on the pump only as long as it takes to completeopen heart surgery.
Components of CPBM 2 main functional units- Pump Oxygenator Tubing (silicone rubber or PVC) Pumps (roller, centrifugal) Oxygenator (membrane oxygenators, oxygenation) Cannulae (Venous, Arterial)
Working schema of CPBMSpecial tubing connected tolarge blood vesselsAllows oxygen-depletedblood to leave the bodyTravels to CPBMMachine oxygenates the bloodReturns blood to the bodythrough a second set of tubing Constant pumping of the machinePushes the oxygenated bloodthrough the body
Tubes- placed away from the surgical site- do not interfere with thesurgeon‟s work Placed in a blood vessel large enough to accommodate tubing & pressure ofpump. 2 tubes insure- blood leaves the body before reaching the heart & returns tothe body after the heart, giving a still & mostly bloodless area to operate. Third tube- inserted very near or directly into the heart, but not connected tothe CPBM- used to flush heart with cardioplegic, a potassium solutionwhich stops the heart. Once the cardioplegic takes effect, the CPBM is initiated and takes over theheart and lung function.
Purpose of CPBM To stop the heart without harming the patient (oxygenated blood mustcontinue to circulate through the body during surgery) The pump does the work of heart (pumping blood through body) andfulfils the function of lungs (oxygenates the blood while pumping) The CPBM is used for 2 primary reasons: Many cardiac surgeries would be impossible to perform with theheart beating- “moving target” - significant blood loss. The pump is used not for surgical need, but to help out if a patient hasheart failure. In some cases, a heart failure patient may be placed onthe pump to support the patient until a heart transplant becomesavailable.
Risks- CPBM Formation of small blood clots in blood processed by machine- canprobably cause stroke, MI or renal failure on returning to bodysbloodstream. The machine can also trigger an inflammatory process that can damagemany of the bodys systems and organs, called „post-pericardiotomysyndrome‟. Post-operative bleeding may be a serious complication, occasionallyrequiring a return to the operating room. Problems with temporary confusion or memory loss.
HistoryDefinition & IntroductionProcedureRecent advances in CABGIndicationsContraindicationsComplications
History of CABG John Gibbon- clinically useful cardiopulmonary bypass (CPBM)- 1953 William Mustard- first direct surgical approach to coronary circulation-1953 Dr. Robert Goetz & Dr. Michael Rohman- first successful surgeons toperform CABG with donor vessel anastomosed to the RCA. The actualanastomosis with the Rosenbach ring developed an atheromatous plaque-occluded the origin of the IMA used. Russian cardiac surgeon, Dr. Vasilii Kolesov- first successful IMA-Coronary artery anastomosis in 1964. 1970‟s- first full decade of CABG (relieved angina & improved QoL)
DefinitionCABG is a surgical procedure in which oneor more blocked coronary arteries are bypassedby a blood vessel graft to restore normal bloodflow to the heart, with an intent to relieveangina & prevent death.Arteries or veins from elsewhere in thepatients body are grafted to the coronaryarteries to bypass atherosclerotic narrowingsand improve the blood supply to the coronarycirculation supplying the myocardium.
2 stages to bypass surgery: Stage 1: healthy blood vessel (the graft) is removed from leg or chest wall. Stage 2: Connecting graft to coronary artery, „bypassing‟ diseasedsegment, improving the blood supply to the heart.1 of the following technique is used:i) A heart-lung machine is used to circulate blood around the body, allowingthe surgeon to operate on the heart (“On-pump” surgery)ii) The „beating heart‟ technique, where the surgery is performed while theheart is still beating and working. This is called „off pump‟ surgery.The operation usually takes between3-6 hoursProcedure
General anaesthesia is administered Removes the veins or preparesthe arteries for graftingSaphenous vein or internal mammaryartery, incisions are madeIncision from patientsneck to navelSawed through breastbone Retracts rib cage & exposes heartConnected to CPBMCardioplegic solution injectedthrough coronary rootSmall opening- just below blockagein diseased coronary arteryBlood redirected through thisopening once the graft is sewn
Cardioplegic solution avoids tissue damage, lowers the temperature ofheart Most patients who undergo CABG, have at least 3 grafts done. CABG builds a detour around one or more blocked coronary arterieswith a graft from a healthy vein or artery. The graft goes around the clogged artery (or arteries) to create newpathways for oxygen-rich blood to flow to the heart. Electric shocks start the heart pumping again after grafting The heart-lung machine is turned off & after the normal bloodflow isresumed, the chest cavity is closed.
Recent advances in CABG Totally endoscopic, minimally invasive CABG with use of a surgicalrobot, doesnt require an incision and patients can often return tonormal activities in few weeks. Keyhole surgery : requires 2-3 inch incision instead of splitting chestopen. Hybrid procedures (minimally invasive bypass surgery and stentedangioplasty in one operation). Off-pump or "beating heart" bypass
Difference- “Off-pump CABG” The bypass is sewed onto the heart, while heart continues beating.Various types of heart stabilizers are used to restrain the heart one sectionat a time so the surgeon can operate on it. The chest is opened through a midline sternotomy incision. After thetarget coronary vessel is exposed & stabilized, it is occluded & opened. A bridging plastic tube - which allows blood flow during suturing -- maybe placed. The bypass graft is then sutured to the coronary artery.
Advantages of off-pump over on-pump CABG Reduced need for blood transfusions Reduced risk of bleeding, stroke and kidney failure Potential for reduced psychomotor and cognitive problems High-risk patients with additional diseases like lung disease,kidney failure and peripheral vascular disease may benefit fromthis kind of operation.
Indications The 2004 ACC/AHA CABG guidelines state CABG is preferredtreatment for Disease of the left main coronary artery (LMCA). Disease of all three coronary vessels (LAD, LCX and RCA). Diffuse disease not amenable to treatment with a PCI. The 2005 ACC/AHA guidelines further state:CABG is preferred treatment with other high-risk patients such asthose with severe ventricular dysfunction (i.e. low ejection fraction), ordiabetes mellitus.
Indications….. contd….. Significant (>50%) left main stem stenosis. Disabling angina despite maximal medical therapy (surgery can beperformed with acceptable risk) 3 vessel disease (survival benefit greater when LVEF < 50%). 2 vessel disease with significant proximal LAD stenosis & eitherEF < 50% or demonstrable ischemia on non-invasive testing.
Contraindications Absence of an open major artery 1 mm or more in diameter beyond theobstructing lesion Absence of viable myocardium in the area supplied by the stenosed artery Co-existing severe non-cardiac condition with poor prognosis
ComplicationsImmediate Complications Bleeding Infection- chest and leg or arm wounds, or lungs Myocardial Infarction Pain Death Irregular heart beatLong Term Complications Stroke Renal failure
IntroductionIndicationsContraindicationsRepair, replacementTypes of valvular prosthesisComplications
Introduction 4 valves in the heart. Valves are strong, thin flaps oftissue, called leaflets. The leaflets open to allow bloodto move forward through theheart during half of theheartbeat, and close to preventblood from flowing backwardduring the other half of theheartbeat.
The tricuspid valve allows blood to movefrom the upper chamber of the heart, theright atrium, into the lower chamber, theright ventricle. The pulmonic valve allows blood tomove out of the right ventricle, whichpumps blood to the lungs. Afterabsorbing oxygen from the lungs, theblood flows back into the heart to the leftatrium. The mitral valve allows blood to movefrom the left atrium into the leftventricle. The aortic valve allows the blood tomove out of the left ventricle, whichpumps the blood out of the heart, to therest of the body.
IndicationsAcquired valvular diseases Infection Infective endocarditis Rheumatic fever Structural valve changes Stretching or tearing of thechordae tendineae orpapillary muscles Fibro-calcific degeneration Dilatation of the valveannulus.Congenital valvular diseases Improper valve size Malformed leaflets Irregularity in the way theleaflets are attached Congenital valve diseases Bicuspid aortic valve disease Mitral valve prolapse
Contraindications Manifestation of end-stage valvedisease Very poor LV function inassociation with a regurgitantlesion Severe fixed pulmonaryhypertension Extensive extra-annular tissuedestruction due to uncontrolledendocarditis Old age Presence of co-morbidities Renal failure Advanced pulmonary disease Severe haemolytic anaemia Severe generalizedarteriopathy Malignant disease Extreme overweight Serious infection untileradication
Valve repair V/S Valve replacementThe potential advantages of valve repair versus valve replacement are:Decreased risk of infectionDecreased need for life-long anticoagulant medicationPreserved heart muscle strength
Types of Valve Repair Surgeries Commissurotomy Decalcification Annulus support Creation of new chords Quadrangular resection of leaflet Patched leaflets and bicuspid aortic valve repair
Consists of separating mitral valve leaflets by mechanical means (valve “dilator”)
Valve Replacement SurgeryRemoval of faulty valve (native valve) and replace itby sewing a mechanical or biological valve to theannulus of the native valve.BiocompatibleAortic valve replacement- most commonly doneAnticoagulant medications (Warfarin) - rest of thepatient‟s life, depending on the type of valvereplacement that was used- reduces probability ofheart attack or strokeNeed to do regular blood test (PT, INR)
Types of Valvular prosthesisBIOLOGICAL VALVESMECHANICAL VALVES
Biological valve Biological valves (tissue orbioprosthetic valves)- made frombovine, porcine & allograft orhomograft. May have some artificial parts to givethe valve support and to aid placement Do not need life-long anticoagulanttherapy after Sx May last at least 17 years without adecline in function
Homograft valve• Human heart valve obtained from adonor after death, frozen & thentransplanted in recipient• Used to replace a diseased aortic valve,or pulmonic valve during the Rossprocedure• Well tolerated by the body as they aremost like native valves• Do not need to take anticoagulantmedications for rest of their lives
Mechanical ValvesMade totally of mechanical parts- toleratedwell by the body.Made of metal or carbon, designed to performfunctions of the patient‟s native valve.Very durable, designed to last a lifetime.The bi-leaflet valve is the most common typeof mechanical valveConsists of 2 carbon leaflets in a ring coveredwith polyester knit fabric.Need to take anticoagulant medications for therest of their livesSome patients who have a mechanical valvereplacement report a valve clicking noise attimes (opening and closing)
Types of mechanical valvesBall prosthesesNon-hooked single-disk prosthesesNon-hooked double-disk prosthesesDisadvantage - must be associated to prescription of an anticoagulant treatmentin long-term
Used to treat aortic valve diseasePatient‟s own pulmonic valve is removedand used to replace a diseased aorticvalve.The pulmonic valve is then replaced by ahomograft valve.Do not need to take anticoagulantmedications for rest of their lives.Ross Procedure
Smaller incisions than traditional heartvalve surgeryOther techniques- endoscopic or keyholeapproaches (also called port access,thoracoscopic or video-assisted surgery)and robotic-assisted surgeryBenefits-a smaller incision (3 to 4 inches-instead of 6- to 8-inch incision withtraditional surgery)smaller scars reduced risk of infection less bleeding less pain & traumadecreased length of stay in the hospital(3 to 5 days) & decreased recovery timeMinimally Invasive Valve Surgery
Full recovery from valve surgery takes about 2-3 monthsTo maintain cardiovascular health after surgery, making lifestyle changes& taking medications- strongly recommendedLifestyle changes include:Quitting smokingTreating high cholesterolManaging high blood pressure & diabetesExercising regularlyMaintaining a healthy weightEating a heart-healthy dietParticipating in a cardiac rehabilitation program, as recommendedFollowing up with your doctor for regular visitsRecovery process
Complications Structural valve deterioration(biological & bioprosthetic valves, deterioration is time-dependent) Valve thrombosis Thromboembolism Prosthetic endocarditis Major bleeding Paravalvular leak