STS Benchmark - Valve Flashcards
Risk factors for TR recurrence after repair.
At 5 years, this remained stable when a standard annuloplasty band was implanted (17% to 18%), but increased to 33% for DeVega suture annuloplasty and 37% when a bovine pericardial band was used. Risk factors for worsening regurgitation included higher preoperative regurgitation grade, poor left ventricular function, transvenous ventricular pacing leads, and either suture or bovine pericardial annuloplasty technique. Interestingly, right ventricular systolic pressure and tricuspid ring size were not significant risk factors for recurrent regurgitation.
You are considering aortic valve replacement for a 41-year-old man with symptomatic aortic valve disease. Which of the following statements is true?
The risk of bleeding complications due to warfarin therapy following mechanical valve replacement is <2% per year.
The risk of reoperative aortic valve surgery prohibits the use of a bioprosthetic valve in patients under age 45.
The Ross Procedure is the procedure of choice for patients 25-45 years old.
A cryopreserved allograft has the greatest freedom from structural deterioration and reoperation at 10 years compared to other valve choices.
The risk of bleeding complications due to warfarin therapy following mechanical valve replacement is <2% per year.
While the Ross procedure is being utilized more frequently in the young adult population there are no data documenting its superiority and freedom from reintervention to the point that it is considered the procedure of choice. However, because of the potential for growth of the pulmonary autograft, it could be considered the optimal aortic replacement valve in the pediatric population. Although many studies have documented previous aortic valve surgery to be an independent risk factor for operative mortality during aortic valve surgery, this risk is not prohibitive. A recent report by Cosgrove et al documented that previous aortic valve surgery is not a significant risk factor for mortality during repeat aortic valve surgery. Patients receiving a mechanical aortic prosthesis need life-long anticoagulation therapy to optimally avoid valve thrombosis and thromboembolic complications. While these patients are at risk for hemorrhagic complications, close monitoring of the INR to keep this value between 2.0 and 3.0 should keep the risk for hemorrhagic complications at less than 2.0% per year. Cryopreserved allograft valves and heterograft bioprosthetic valves have roughly a 90-95% freedom from structural valve deterioration at 10 years. Modern mechanical valves are essentially free from structural failure. Non-structural dysfunction can occur with mechanical valves, as with other valve choices, and can lead to the need for reoperation. Because no valve replacement option is perfect, each patient should be informed of the benefits and limitations of each option and should be allowed the freedom to choose which choice is best for them.
One week following surgery for mitral regurgitation, a radionuclide study reveals an increase in resting ejection fraction and no change in end-diastolic volume of the left ventricle compared to a preoperative study.
What is the likely explanation?
Perivalvular leak after mitral valve replacement.
Resting ejection fraction (EF) often decreases after mitral valve surgery because of mechanical factors or problems with myocardial protection. Mechanical factors include division of the chordae tendineae, a rigid ring in the mitral annulus, and increased afterload due to elimination of the low resistance leak to the left atrium. Some evidence suggests that resting EF may improve after valve repair, but this has only been reported with a decrease in end-diastolic volume of the left ventricle (LYEDV). Resting EF and LVEDV decrease with flexible rings. Elastance, a load-independent measure of contractility, is a better parameter than EF for studying the effects of mitral surgery on function. Decreased elastance should decrease resting EF. Surgical preservation of chordae tendineae might minimize deterioration of EF but this has not been reported to increase resting EF. A perivalvular leak is functionally equivalent to mitral regurgitation and is similar to the preoperative state. This is the most likely cause of the functional changes described.
A frail 70-year-old woman is currently undergoing mitral valve replacement with a bioprosthesis. As cardiopulmonary bypass is discontinued bleeding is noted to originate posteriorly from the vicinity of the left atrioventricular junction. The surgeon should resume bypass, arrest the heart and…
perform internal repair and implant a non-oversized valve
Elderly patients are more prone to develop posterior ventricular disruption during or following mitral valve replacement (MVR), and this may occur at the mid ventricular level or at the atrioventricular junction. Bleeding from this complication may be massive. External inspection of the heart allows the surgeon to see only the point of egress of blood, and the act of inspection for posterior bleeding following MVR carries danger. Repair of ventricular disruption is difficult, and the mortality of this complication is very high. External repairs jeopardize the circumflex coronary artery, its marginal branches and the coronary sinus. Again, exposure of the posterior atrioventricular groove following MVR is difficult and dangerous, and the precise site of bleeding usually cannot be identified for accurate suture repair. Most authors recommend internal repair utilizing a patch of pericardium or synthetic material, followed by careful implantation of a low profile mechanical prosthesis. Internal inspection of the heart and removal of the valve prosthesis allow a more thorough inspection and evaluation of the injury. If injury or compromise of the circumflex territory is suspected as part of the complication, then a distal coronary artery anastomosis should be performed following removal of the initial prosthesis and prior to replacing the valve again.
For patients with bAV, are calcific deposits the rule for most of these patients by age 30?
The majority of patients with congenitally bicuspid aortic valves do not have significant aortic valve obstruction in the early years of life, but abnormal valvular calcification is present in nearly all these patients by 30 years of age. In patients who require aortic valvotomy in infancy or childhood, a successful procedure does not eliminate progressive degenerative changes. Calcification often mandates repeat valvotomy or valve replacement during adult life.
Most common etiology of AS in patients over 65?
Fibrocalcific aortic stenosis results from occult degenerative changes characterized by collagen disruption and calcific deposits. The calcification characteristically begins in the sinuses of Valsalva and progresses to involve fusion of the commissures. Extensive calcification of the leaflets with extension to the adjacent aortic wall and onto the anterior leaflet of the mitral valve are late findings. This form of aortic valve disease is the most common etiology of aortic stenosis in patients over 65 years of age.
How common is bAV in the general population?sc
One of the most common underlying causes of aortic stenosis is a congenitally bicuspid valve. This occurs in approximately 1% of the general population.
Describe the pathophysiology of rheumatic fever in its progression to AS?
Rheumatic fever may be associated with a valvulitis that can progress over time to aortic stenosis. The inflammatory process results in lymphocytic infiltration, edema, and neovascularization of the valve leaflets. Fusion of the valve leaflets along the commissures and adjacent cusps is frequent, as is leaflet calcification. The result is an immobile ring of rigid valvular tissue which appears as a fixed triangular central orifice.
Compared to bioprosthetic aortic valve replacement, the Ross Operation (pulmonary valve and root autotransplant to the aortic root and homograft pulmonary root replacement) is characterized by?
reduced incidence of endocarditis.
increased operative time.
anteroseptal myocardial infarction.
increased blood loss.
Autotransplantation of the pulmonary valve or root as a composite to the aortic position was initially performed to obviate the problem of early calcification and degeneration of tissue valves in young patients. Ross began a series of such autotransplants in 1967. This experience has confirmed the durability of the pulmonary valve in the aortic position, and the specific problem of early calcification has been eliminated. The primary technical concerns of the procedure relate to achieving meticulous hemostasis and avoiding injury to the left anterior descending coronary artery and its first septal perforating branch during excision of the pulmonary root. Right heart failure has not been reported.
A 48-year-old, 75 kg man had severe mitral valve regurgitation and a non-diseased left-dominant coronary system. Mitral valve repair was performed with a large quadrangular resection of the posterior leaflet and ring annuloplasty. After weaning from bypass the patient has persistent ST-segment elevation in leads II, III, and AVF, and posterior wall hypokinesis is noted on echocardiography. There is no residual mitral insufficiency and no systolic anterior motion. BP is 85/60 mmHg, PA pressure is 55/32, and cardiac output is 2.5 L/min.
Differential?
The best treatment is?
The potential causes of ST-segment elevations in leads II, III, and AVF after mitral valve repair or replacement include poor perfusion secondary to transient air in the inferior ventricular (usually right coronary) circulation, a current of injury secondary to ischemia from inadequate myocardial protection, coronary spasm and myocardial infarction. ST-segment changes secondary to coronary air, from a current of injury or from coronary spasm should be transient. Such ECG changes should normalize if adequate perfusion pressure and hemodynamics are maintained, although nitrates and calcium channel blockers might be helpful if coronary spasm is suspected. If the ST-segment elevations are persistent and associated with systemic hypotension, pulmonary hypertension and low cardiac output as described, then myocardial infarction is the most likely diagnosis. Following a large quadrangular resection of the posterior leaflet, kinking or injury to the circumflex coronary artery is the most likely explanation. Similarly, the circumflex coronary artery may be injured by sutures during mitral valve replacement. In either case the best treatment is to perform coronary bypass to the distal circumflex marginal artery. In an unstable patient, this should be done immediately, before transmural infarction and permanent damage occur. To terminate the operation and proceed to coronary angiography is unwise. Placing an intra-aortic balloon pump provides hemodynamic support, but it does not correct the underlying problem and the delay risks irreversible transmural infarction. Since the mitral valve is competent and since the artery may have been irreversibly damaged, there is no indication to take down the repair and replace the valve.
A 43-year-old woman had mitral valve prolapse and moderate mitral regurgitation secondary to a flail middle scallop of the posterior leaflet. Her left ventricular ejection fraction was 60%. Mitral valve repair was done with a partial posterior leaflet quadrangular resection, posterior annular plication, leaflet reapproximation, and a #28 ring annuloplasty. Her post-bypass transesophageal echocardiogram demonstrates an excellent repair with complete elimination of mitral regurgitation and no gradient. Twelve hours after surgery the patient has had a moderate amount of bleeding through the thoracostomy tubes. Blood pressure is now 112/67, RA is 10 and PA is 36/14. Her cardiac index has decreased to 1.6 and PA oxygen saturation is now 45%. Hemoglobin is 10gm/dl. The epinephrine infusion is increased from 2 to 4 mcg/min and her heart is increased from 70 to 90 with atrial pacing.
Echo shows a redundant posterior leaflet.
What is happening? What do you do?
Systolic anterior motion of the mitral valve leading to aortic outflow tract obstruction is a well recognized complication of mitral valve repair.
It is caused by a repair that leaves the coaptation point of the anterior and posterior leaflet too anterior toward the aortic valve and sometimes by too small of a annuloplasty ring. It is seen in patients with a large, redundant posterior leaflet. In this case, this was was not recognized.
An appropriate initial action would have been to initially perform a sliding plasty of the posterior leaflet and a larger annuloplasty ring. Given that this was not done, reasonable options (after failure of medical management including volume loading, removal of inotropes, beta-blockade, etc.) include return to the operating room to redo the repair with a larger ring and a sliding plasty or mitral valve replacement with a low-profile mechanical valve.
