Late Outcome Following Systemic Tricuspid Valve Replacement







Age: 55 years


Gender: Female


Occupation: Accountant


Working diagnosis: Congenitally corrected transposition of the great arteries, ventricular septal defect, pulmonary stenosis



HISTORY


The patient was well during her early childhood, only coming to medical attention when a heart murmur was heard at the age of 11 years. She was initially diagnosed (elsewhere, and incorrectly) as having TOF. She remained unoperated and relatively well. She was advised to avoid pregnancy because of her ACHD.


At age 31, she presented with progressive functional deterioration and was referred to an ACHD center. Repeat cardiac catheterization established the diagnosis of situs inversus with mirror-image atrial arrangement, dextrocardia, discordant AV and ventriculoarterial connections (CCTGA), a large VSD, severe pulmonary stenosis, and a single coronary artery from the right coronary sinus.


Soon thereafter she underwent VSD patch closure with placement of a LV-to-pulmonary artery (PA) valved conduit.


The immediate postoperative course was complicated by complete heart block; thus a transvenous permanent pacemaker, VVI mode, was inserted.


The early postoperative period was complicated by recurrent episodes of atrial flutter, ultimately requiring a low dose of amiodarone for control. Thereafter she was well, with a marked improvement in symptoms and functional capacity.


Within 2 years of surgery she had symptoms and signs of pulmonary venous congestion and had developed a new pan-systolic murmur. The echocardiogram and cardiac catheter performed at that time showed severe regurgitation of the morphologically tricuspid (systemic AV) valve. Consequently, 3 years after her initial surgery, she underwent tricuspid valve replacement with a 25-mm Bjork-Shiley mechanical prosthesis.


Despite developing paroxysmal atrial flutter for which she was treated with atenolol, she remained very well with excellent functional capacity and only mild symptoms of exercise limitation. She was seen for routine evaluation.





Comments: CCTGA is an uncommon congenital cardiac anomaly. It accounts for less than 0.5% of all congenital heart disease. The most common associated defects are VSD (60%–80%), and pulmonary stenosis, or, more appropriately, LVOT obstruction (30%–50%). Tricuspid valve abnormalities are also common (14%–56%). Ebstein malformation, dysplasia of the valve, abnormalities of the subvalve apparatus, and straddling and overriding with respect to the VSD have all been reported.


Neither her ACHD nor anticoagulation is an absolute contraindication to pregnancy. The outcomes of pregnancy in 22 women with CCTGA have been reported. There were a total of 60 pregnancies resulting in 50 live births, with no pregnancy-related deaths, and none of the live infants was diagnosed with congenital heart disease.


Patients with CCTGA are at high risk of developing AV block whether operated on or not. The sinus node is normally positioned, but the AV conduction tissue is grossly abnormal. At 20-year follow-up, 45% of unoperated patients will have developed third-degree heart block, slightly higher than the suggested figure of 30%. Subsequently, it has been reported that spontaneous complete heart block in this population occurs at a rate of about 2% per year. Surgically induced heart block is still common. The anatomy of the AV node was described in 1973 by Bob Anderson. While this knowledge transformed the incidence of complete heart block in those undergoing surgery, it remains a risk.


Several authors have shown that the regular AV node located at the apex of the triangle of Koch rarely gives origin to a penetrating AV conduction bundle. Instead, there is an anterior course of an anomalous AV node and penetrating bundle, which is commonly located beneath the opening of the right atrial appendage at the lateral margin of the area of pulmonary-to-mitral valve continuity. The elongated bundle has a superficial course underneath the right anterior facing leaflet of the pulmonary valve and descends for some distance before branching. Histological study often reveals pathologic changes within the bundle, such as fibrosis, even in the absence of abnormal conduction.


The development of new tricuspid regurgitation within 2 years of operation is not surprising in CCTGA after a conventional (classic) repair. Voskuil and colleagues studied the postoperative outcomes of 73 patients with CCTGA and found that RV function and tricuspid valve function both deteriorated with age. These complications developed more frequently after conventional intracardiac operations compared with patients undergoing palliative intervention or no surgery at all. Indeed, several studies have shown that RV dysfunction and tricuspid regurgitation both deteriorate more frequently following intracardiac operation than in patients either unoperated or treated with closed heart procedures.


Tricuspid valve function depends on the loading conditions of the ventricles and the secondary effects on septal geometry. Interventions that increase RV volume or decrease LV pressure induce and worsen tricuspid regurgitation. Graham and colleagues reviewed 182 adult patients from 19 institutions. The strongest risk factors for clinical congestive heart failure and RV dysfunction included tricuspid valve surgery, important tricuspid regurgitation, history of any open-heart surgery, and pacemaker therapy.


Atrial arrhythmia is common. Connelly and associates reported outcomes in 52 patients with CCTGA. During a period of approximately 10 years of follow-up, 25% died and 36% of the survivors had documented atrial fibrillation, atrial flutter, or supraventricular tachycardia.





CURRENT SYMPTOMS


Now 22 years after valve replacement, the patient is asymptomatic. She works full time and tolerates long walks and occasional vigorous activity.


NYHA class: I




CURRENT MEDICATIONS





  • Warfarin (target INR 2.5–3.5)



  • Aspirin 81 mg once daily



  • Atenolol 50 mg once daily






Comments: Patients with all types of mechanical valves require antithrombotic prophylaxis. Bjork and Iienze in 1975 reported that among patients (without complex ACHD) with the Bjork-Shiley spherical disk valves who received no prophylaxis or prophylaxis with aspirin alone, thromboemboli occurred in 23% per year.


In patients who have mechanical valves and additional risk factors such as atrial fibrillation, myocardial infarction, left atrial enlargement, endocardial damage, and low ejection fraction, the American College of Chest Physicians recommended adding low-dose aspirin, 75 to 100 mg/day.





PHYSICAL EXAMINATION





  • BP 110/70 mm Hg, HR 75 bpm, oxygen saturation 98%



  • Height 150 cm, weight 45.4 kg, BSA 1.38 m 2



  • Surgical scars: Bilateral thoracotomy and median sternotomy scars



  • Neck veins: JVP was 4 cm above the sternal angle.



  • Lungs/chest: Chest was clear. Apex beat was to the right.



  • Heart: Normal prosthetic heart sounds. The time between the second heart sound and the opening click of the mechanical valve was wide, indicating relatively normal LA pressures. There was a short, grade 2–3/6 systolic ejection type murmur at the left sternal border. There was no diastolic murmur. Peripheral pulses were palpable and normal in character.



  • Abdomen: Soft with no organomegaly



  • Extremities: No peripheral edema






Comments: Her clinical examination is in keeping with her underlying diagnosis and good clinical status. The finding of a right-sided apical impulse is seen in about 20% of patients with CCTGA. The atrial situs is inversus (mirror image) in 5% to 8% of patients, and solitus (usual) in 92% to 95%.


At the time of her initial VSD closure and conduit placement, the surgeon elected to expose the heart using two thoracotomy incisions because of, as he described, “an awkward anatomy with situs inversus.”


The short ejection systolic murmer implies little LVOT/conduit obstruction.


The absence of a diastolic murmur argues against significant conduit valve regurgitation, especially since the conduit is substernal.


The liver in situs inversus will be left-sided, so one must palpate in the correct area.





LABORATORY DATA






























Hemoglobin 14.0 g/dL (11.5–15.0)
Hematocrit/PCV 43% (36–46)
MCV 94 fL (83–99)
Platelet count 168 × 10 9 /L (150–400)
Sodium 139 mmol/L (134–145)
Potassium 4.2 mmol/L (3.5–5.2)
Creatinine 0.62 mg/dL (0.6–1.2)
Blood urea nitrogen 2.8 mmol/L (2.5–6.5)


OTHER RELEVANT LAB RESULTS












PT 33.1 seconds
INR 3.04





Comments: The normal hemoglobin and MCV are somewhat remarkable in the context of chronic warfarin therapy.


In patients who have mechanical valves and additional risk factors such as atrial fibrillation, myocardial infarction, LA enlargement, endocardial damage, and low ejection fraction, the American College of Chest Physicians recommended a target INR of 3.0 or a range of 2.5 to 3.5.





ELECTROCARDIOGRAM



Figure 58-1


Electrocardiogram.




FINDINGS





  • Heart rate: 76 bpm (paced)



  • QRS axis: Extreme right-axis deviation



  • QRS duration: 172 msec



  • The ECG showed characteristic loss of precordial voltage in the left chest leads because the patient has dextrocardia.






Comments: Patients with CCTGA have a higher incidence of preexcitation; the incidence of left- versus right-sided bypass tracts appears to be equal.


The current ECG ( left ) shows a paced ventricular rhythm with atypical atrial flutter at 200 bpm and AV dissociation.


The patient is well, but the atrial arrhythmia should be managed and consideration should be given to an AV synchronous pacing mode to maximize function and perhaps prevent deterioration.





CHEST X-RAY



Figure 58-2


Posteroanterior projection.




FINDINGS





  • Cardiothoracic ratio: 63%



Atrial and abdominal situs inversus (mirror image) with dextro/mesocardia. There was mild-to-moderate cardiomegaly.





Comments: It is just possible to discern the presence of bronchial situs inversus (long morphologic left mainstem bronchus to the right-sided lung field), which indicates atrial situs inversus. This is supported by the mirror-image visceral situs (stomach bubble to the right, liver shadow to the left), and the course of the pacing wires. Atrial and abdominal situs are expected to concur.


Both valve prostheses can be seen, the tricuspid valve replacement (TVR) is shown centrally, and the frame of the LV-PA tissue valve is seen in the lateral projection.




Figure 58-3


Lateral view.




FINDINGS


As noted in the posteroanterior projection there is calcification of the left diaphragmatic pleura and thickening of the lower left pleural recess. The heart is very close to the posterior border of the sternum.




EXERCISE TESTING




















Exercise protocol: Bruce
Duration (min:sec): 12:30
Reason for stopping: Leg pain
ECG changes: Paced








































Rest Peak
Heart rate (bpm): 75 170
Percent of age-predicted max HR: 103
O 2 saturation (%): 98 93
Blood pressure (mm Hg): 110/70 150/85
Peak V o 2 (mL/kg/min): 28
Percent predicted (%): 60
Metabolic equivalents: 9.4

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Sep 11, 2019 | Posted by in CARDIOLOGY | Comments Off on Late Outcome Following Systemic Tricuspid Valve Replacement

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