Type IIa Familial Hypercholesterolemia With Hypoplastic Aortic Root
A Tarhan, Y Arslan, T Kehlibar, F Yapici, A Özler
coronary artery bypass cabg, familial hypercholesterolemia fh, supracoronary aortic valve replacement
A Tarhan, Y Arslan, T Kehlibar, F Yapici, A Özler. Type IIa Familial Hypercholesterolemia With Hypoplastic Aortic Root. The Internet Journal of Thoracic and Cardiovascular Surgery. 2004 Volume 7 Number 1.
Aortic hypoplasia, aortic root, and valvular involvement associate with homozygous form of Familial Hypercholesterolem (FH) less commonly. We describe a 32 year old female patient with a previous dacron patch aortoplasty. The echocardiographic supra-aortic gradient was maximally 120 mmHg. Angiographicy revealed 40% left and 50% right ostial stenosis. Annular and supra annular stenosis was revealed by using the Manouguian type aortic root enlargement procedure with a unique oval shaped dacron patch. Before closing the patch completely, a supracoronary positioned mechanical aortic valve was implanted. Two saphenous bypasses for left anterior descending and right coronary arteries were added because of the ostial stenosis. The postoperative period was uneventfull. We suggest that all patients with FH should be evaluated in detail with CT or MRI for possible hypoplastic aortic root. Therapy of this kind of FH is still under debate. We evaluated the therapy modalities and small aortic root problems in this report.
Coronary atherosclerosis is one of the well-defined and unavoidable complication of familial hypercholesterolemia (FH). Less commonly, aortic hypoplasia, aortic root and valvular involvement associates with homozygous form of FH. Type IIa familial hypercholesterolemia is a rare disorder (at 1/1,000,000 births) characterised by hypercholesterolemia with elevated LDL cholesterol, normal triglyceride concentrations and tendinous and skin xanthomas (1). Premature coronary atherosclerosis is a well-known and a frequent complication of the disease (2,3). LDL receptors play direct or indirect role in aortic mural development and vascular growth (4). Aortic root and valve involvement, especially aortic stenosis generally necessitates aortic root enlargement for relieving the left ventricular outflow tract obstruction (5,6,7).
A 32-years old female patient was admitted to our hospital with severe fatigue, palpitation and exertional dyspnea in the last ten years. In her family history her brother died from myocardial infartion at 28 years. She had disseminated xhantomas, xanthalesma, and type IIa familial hypercholesterolemia. Functional capacity of the patient was NYHA III. She had been operated one year ago because of supravalvular aortic stenosis with a dacron patch plasty under cardiopulmonary bypass. A thrill was palpated in the aortic area and 4/6 systolic murmur radiating to neck. Left ventricular (LV) systolic strain and LV hypertrophy were present in ECG. There was a 120 mmHg gradient in the aorta supravalvarly detected by echocardiography. LVEF was 82%. Quantitative coronary angiography revealed 40% left, 50% right ostial stenosis. Left ventriculography was normal.
Familial type IIa hypercholesterolemia, aortic stenosis, coronary artery disease were diagnosed with these findings. Coronary artery bypass surgery and aortic valve replacement was planned. A pulmonary artery catheter (Edwards Swan Ganz Cath. 93A 113H-7-H) via the internal jugular vein and radial artery catheter was inserted. Because of the reoperation a right femoral arterial cannulation was planned. After median sternotomy the ITA was harvested. It was severely atherosclerotic and had no sufficient flow. Before aortic cannulation, heparin (4mg/kg ) was given to bring the activated clotting time over 450 seconds. 21 F femoral cannula was inserted into the right femoral artery, two staged venous cannula into the right atrium. For myocardial protection, 28°C systemic hypothermia, antegrade – retrograde cold blood cardioplegia was administered. During exploration, the aortic root was hypoplastic and there was an oval shaped dacron patch on it (figure 1).
Even after we resected the aortic valve completely, the annulus was still very small as 1cm in radius. Annular and supra annular stenosis was revealed by using the Manouugian type aortic root enlargement procedure with a unique oval shaped shaped dacron patch (Figure 2,3).
Before closing the patch completely, a supracoronary positioned mechanical aortic valve (number 23 St.Jude) was implanted (Figure 4,5).
And two saphenous bypasses for left anterior descending and right coronary arteries were added because of the ostial stenosis. The sinotubular area, which was narrow like the aortic annulus, was dilated with a oval shaped Gore-Tex patch (Figure 2).
Postoperatively the patient’s functional capacity was NYHA I. Total and LDL cholesterol levels were 200 mg/dl under simvastatin (dose 40 mg daily) therapy. She was in a plasmapheresis program for lipid lowering.
Detection of this lesion has profound implications for these patients. If surgical procedures are under consideration for aortic valve and/or supravalvular disease, diminished size of the native aortic root is important information for surgical planning. Narrowing of the external diameter of the ascending aorta should be detected preoperatively by ultrafast computed tomography or magnetic resonance imaging. (4, 7)
Supravalvular stenosis can be treated by different techniques; symmetric (Brom’s three patch technique) and asymmetric aortic dilatation. A study in comparing to these techniques showed no difference between the postoperative aortic gradients. However, reconstruction of the aortic root with autologous pericardial patches in each sinus after transection of the aorta has the advantage of symmetry while restoring the normal aortic root anatomy.(8)
Coronary artery disease complicating the supravalvular aotic stenosis is really a problem left main coronary artery might have been involved. According to most authors, arterial grafts are preferable. In one case it was reported that with a modification of Brom’s technique left main coronary artery was dilated with a pericardial patch (9,10). Complications of annular dilatation procedures are prolonged myocardial ischaemia, increased post-operative drainage, blood products or whole blood transfusion necessity, and a risk of thrombo-embolism. Abnormal coronary artery anatomy makes this operation more difficult. It is important to implant the prosthetic valve with minimal systolic gradient in order to reduce the left ventricular mass. Management of familial hypercholesterolemia improved considerably with HMG-CoA reductase inhibitors. These agents provide a marked decrease in plasma LDL cholesterol levels in patients with familial hypercholesterolemia and these effects may be enhanced when combined with other lipid lowering drugs such as bile acid-resins and probucol (11,12,13,14). Patients with homozygous FH have markedly elevated low density lipoprotein(LDL) cholesterol levels which are refractory to standard doses of lipid lowering therapy. Raal and colleques, suggested that atorvastatin more than 80 mg daily dose has no further inhibitory effect of cholesterol synthesis.(15) We started simvastatin therapy as soon as FH diagnosis verified. Patient's total and LDL cholesterol levels reduced markedly (24% and %28 respectively) at month six. Warfarin usage may limit the choice of statin and cholestyramine. Cholestyramine and colestipol may decrease the effect of warfarin. Fenofibrate potentiates the effect of warfarin (16). An expensive treatment option LDL-aphresis, not only reduce serum cholesterol levels, but also may delay the progression of coronary artery disease and regress valvar stenosis (17,18). With recent encouraging advances in gene therapy regarding the restoration of the defective gene functions (19), improvement of the prognosis will be possible in the near future.
Coronary artery disease and aortic stenosis are serious complications of familial hypercholesterolemia. Surgical intervention presents difficulties in some cases for aortic stenosis because of highly calcified and narrow aortic root. Surgical strategy and therapy of “the hypercholestrolemic valvulopathy” have troublesome which need carefull planning on surgical and medical therapy.
In our case previous grafted aorto-patchplasty operation, heavily fibrotic, and excessively narrowed aortic root limited us from putting into practice many surgical options. This is the reason why we choose an aortic mechanical valve supracoronarily.
Dr.Yücesin Arslan Bankacılar sokak,Mine Apt Daire 42 Sahrayıcedit-Erenköy İstanbul-TURKEY E mail: email@example.com