Hypertrophic cardiomyopathy





CASE 8-1


Transplant for hypertrophic cardiomyopathy


This 26-year-old woman with hypertrophic cardiomyopathy and prolonged QT syndrome was referred for heart transplantation for low-output heart failure with clinical symptoms of fatigue and marked exercise intolerance with New York Heart Association (NYHA) class III symptoms despite maximal medical therapy. Right heart catheterization documented a pulmonary artery pressure of 24/9 mm Hg with a pulmonary wedge pressure of 10 mm Hg. Cardiac output was 5.8 L/min, with a cardiac index of 2.9 L/min.



Fig 8.1


Transgastric short-axis view shows severe hypertrophy of left ventricle with septal thickness of 2.4 cm (left). Transgastric long-axis view (right) also shows severe hypertrophy of left ventricle.



Fig 8.2


A section through apex of freshly explanted heart (left) demonstrates severe hypertrophy of ventricular myocardium. At pathologic examination (right), heart was severely hypertrophied (cardiac mass = 655 g), with pattern typical for hypertrophic cardiomyopathy; left ventricular cavity was extremely small.



Fig 8.3


Histologic examination revealed severe cardiomyocyte disarray, with mild-to-moderate interstitial fibrosis.






CASE 8-2


Myomectomy for dynamic left ventricular outflow tract obstruction


This 64-year-old man was referred for surgical intervention for hypertrophic cardiomyopathy with severe dynamic subaortic obstruction. He had an 8-month history of increasing exertional dyspnea, chest pain, and syncope. Echocardiography showed hypertrophic cardiomyopathy with severe outflow obstruction and severe mitral regurgitation. Coronary angiography showed no significant epicardial coronary artery disease.



Fig 8.4


Four-chamber TEE view (left) demonstrates systolic anterior motion of mitral valve leaflet ( arrow). Color Doppler (right) shows both increased outflow tract velocity ( green indicates variance due to high flow velocity with signal aliasing) and severe mitral regurgitation (MR).



Fig 8.5


Transgastric short-axis view at mitral valve level shows severely hypertrophied left ventricle; there is systolic anterior motion (SAM) of anterior mitral leaflet with interventricular septal contact (left) and color flow (right) demonstrating subaortic obstruction.



Fig 8.6


In different patient without hypertrophic cardiomyopathy, example of using transgastric apical view for evaluation of left ventricular outflow is shown. Image plane is angulated anteriorly from deep transgastric four-chamber view to show aortic valve (left). Then, pulsed or continuous-wave Doppler examination of flow is recorded, in this case showing normal velocity of 0.7 m/s (right). Maximal velocity may be underestimated by this approach, as it is not always possible to obtain parallel intercept angle between ultrasound beam and direction of blood flow. However, actual velocity is at least as high as recorded velocity.



Fig 8.7


In this patient with hypertrophic cardiomyopathy, continuous-wave Doppler from transgastric long-axis view demonstrates late-peaking, high-velocity systolic signal with maximum velocity of 3.4 m/s, corresponding to maximum pressure gradient (PG) of 46 mm Hg. PG may be even higher when patient is awake and active.



Fig 8.8


At surgery, left ventricular outflow tract is approached via ascending aorta, and through passively opened aortic valve. In normal example in which aortic valve has been removed, structures visible in LVOT include interventricular septum (left) anteriorly and AML (right) posteriorly.



Fig 8.9


In this patient with hypertrophic cardiomyopathy, trough of septal myocardium was removed anteriorly with depth and length of approximately 1 cm, taking care to avoid creating VSD. Because of severe subaortic obstruction with systolic anterior motion of AML, mitral valve was replaced with low-profile mechanical valve. Both anterior and posterior chords were preserved, but anterior leaflet was partly excised, with remnants of AML incorporated into medial and lateral suture lines.




Comments


Hypertrophic cardiomyopathy is an autosomal dominant inherited disease that is characterized by asymmetric hypertrophy of the left ventricle, diastolic dysfunction, and, in a subset of patients, dynamic subaortic obstruction. There are several different patterns of left ventricular hypertrophy but all have in common relative sparing the basal segment of the inferior–posterior left ventricular wall. In some cases, symptoms are predominantly a result of diastolic dysfunction, as in the first Case 8-1 . Typically, relaxation is decreased early in the disease, with decreased compliance occurring late in the disease. Diastolic dysfunction is associated with elevated filling pressures and a reduced forward cardiac output, resulting in symptoms of exertional fatigue and dyspnea.


The dynamic outflow obstruction that occurs in some patients is related to systolic anterior motion of the mitral leaflets and an anatomically abnormal mitral valve. There is often coexisting mitral regurgitation due to malcoaptation of the leaflets at the site of systolic anterior motion. Symptoms of angina, dyspnea, and syncope occur in some, but not all, patients with outflow obstruction. Outflow obstruction is dynamic in that it varies during the ejection period, with the maximal obstruction in late systole. In addition, the degree of outflow obstruction varies with loading conditions: typically, it increases with a decrease in ventricular volume (e.g., hypovolemia), a decrease in systemic vascular resistance (e.g., with vasodilators), or an increase in contractility (e.g., with exercise).


Treatment options include medical therapy, percutaneous ablation of the septal myocardium in selected patients, and surgical myomectomy, sometimes with concurrent mitral valve replacement.


Suggested reading




  • 1.

    Woo A: Hypertrophic cardiomyopathy: echocardiography in diagnosis and management of patients (including stress testing). In Otto CM, editor: The Practice of Clinical Echocardiography, ed 5, Philadelphia, 2016, Elsevier.


  • 2.

    Gersh BJ, Maron BJ, Bonow RO, et al: 2011 ACCF/AHA guideline for the diagnosis and treatment of hypertrophic cardiomyopathy: executive summary: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines, Circulation 124(24):2761, 2011.


  • 3.

    Caselli S, Maron MS, Urbano-Moral JA, et al: Differentiating left ventricular hypertrophy in athletes from that in patients with hypertrophic cardiomyopathy, Am J Cardiol 114(9):1383–1389, 2014.


  • 4.

    Hensley N, Dietrich J, Nyhan D, et al: Hypertrophic Cardiomyopathy: A Review, Anesthesia Analgesia 120:554–559, 2015.


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Dec 30, 2019 | Posted by in CARDIOLOGY | Comments Off on Hypertrophic cardiomyopathy

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