Cards: Myocardial disease-HCM, RCM, tumors Flashcards
What are the pathophys mechanisms that contribute to HCM?
The major pathophysiologic mechanisms contributing to signs and symptoms of HCM are diastolic dysfunction and dynamic left ventricular outflow tract (LVOT) obstruction.
Diastolic dysfunction arises from abnormal relaxation and poor myocardial compliance, leading to an increase in left ventricular filling pressures. Dynamic LVOT obstruction, present in approximately two thirds of patients, results from septal hypertrophy and anterior displacement of the mitral valve apparatus; this displacement also is associated with decreased coaptation of the valve leaflets and resultant mitral regurgitation
What exacerbates LVOT in HCM?
Dynamic LVOT obstruction is exacerbated by any drug therapy that increases contractility, such as digoxin or other inotropic agents. Obstruction is also worsened by reduced ventricular preload, such as from dehydration, or afterload, such as from vasodilator therapy.
Physical signs of HCM?
- The carotid upstroke typically is rapid and may be bifid: pulsus bisferiens—”twice beating”
- JVP may demonstrate a heightened a wave
- apical impulse typically is sustained, localized, and may be bifid or trifid
- An S4 is frequently present, especially in younger patients
- Paradoxical splitting of the S2 also may occur with significant LVOT obstruction.
What is the murmur of LVOT?
Systolic murmur
How is the LVOT murmur of HCM best augmented? How do you distinguish it from other systolic murmurs?
Augmentation of the murmur occurs during maneuvers that decrease preload (squat-to-stand, Valsalva strain) and afterload (amyl nitrite inhalation). These maneuvers can help distinguish HCM from other causes of systolic murmurs, such as aortic stenosis and mitral regurgitation. Contrary to HCM, the murmurs of aortic stenosis and mitral regurgitation diminish with maneuvers that reduce preload.
How is LVOT diagnosed?
LVOT obstruction is considered significant when the calculated pressure gradient is either 30 mm Hg or greater at rest, or 50 mm Hg or greater with provocation. In 80% to 90% of patients with HCM, electrocardiography (ECG) demonstrates findings of left ventricular hypertrophy.
In patients with HCM, who should undergo risk stratification for SCD? Who should get an ICD?
Placement of an implantable cardioverter-defibrillator should be considered in patients with hypertrophic cardiomyopathy with one or more major risk factors for sudden cardiac death: prior cardiac arrest, massive myocardial hypertrophy, family history of sudden cardiac death, ventricular tachycardia, blunted blood pressure response to exercise, unexplained syncope.
What pharmacologic treatment can be used for HCM?
Negative inotropic agents are the cornerstone of medical therapy for patients with symptomatic obstructive HCM. Negative inotropes (β-blockers, nondihydropyridine calcium channel blockers [verapamil], and disopyramide) depress contractility, thereby reducing the intraventricular flow velocities that predispose to LVOT obstruction. These agents also lengthen diastole, facilitating more time for ventricular filling. Appropriate drug therapy suffices for most patients with symptomatic obstructive HCM, although high doses may be required. Positive inotropes (such as digoxin), vasodilators, and high-dose diuretics should be avoided, as these drugs exacerbate LVOT obstruction.
Who should get a septal myectomy for HCM?
For patients with persistent, severe, drug-refractory symptoms caused by obstructive HCM, septal reduction therapy with surgical septal myectomy or percutaneous alcohol septal ablation should be considered.
Surgical myectomy is the gold standard therapy for relief of LVOT obstruction. In this procedure, a transaortic approach is typically used to resect the ventricular septum, often extending the resection to the base of the papillary muscles ( Figure 14 ). In experienced centers, symptom relief with surgical myectomy occurs in more than 90% of patients with a low perioperative mortality rate (<1%). Long-term survival following myectomy has been found to be comparable to the expected survival of the general population.
Who should undergo genetic screening for HCM?
All first-degree relatives of patients with HCM should undergo screening for the disease.
What is a primary restrictive CM?
Primary restrictive cardiomyopathy is an idiopathic disorder characterized by nondilated, poorly compliant ventricles, leading to severe diastolic dysfunction, elevated filling pressures, and heart failure. In rare cases, restrictive cardiomyopathy is familial, with an autosomal dominant pattern of inheritance. Restrictive cardiomyopathy is a diagnosis of exclusion and must be distinguished from constrictive pericarditis (see later), eosinophilic syndromes, radiation-induced disease, storage diseases (such as Fabry disease, hemochromatosis), as well as infiltrative cardiomyopathies, such as amyloidosis and sarcoidosis.
How is RCM diagnosed?
Patients with restrictive cardiomyopathy may present at any age, with symptoms and signs of pulmonary and systemic congestion. The diagnosis can be considered when there is severe diastolic dysfunction and dilated atria in the absence of ventricular hypertrophy or cavity dilatation.
-Endomyocardial biopsy can be performed for patients with suspected restrictive cardiomyopathy to evaluate for infiltrative disease,
How do you separate out a RCM from a constrictive pericarditis?
A hemodynamic evaluation is frequently required to distinguish restrictive cardiomyopathy from constriction. As a myocardial disease, restrictive cardiomyopathy may predominantly affect left ventricular filling, resulting in elevated left ventricular end-diastolic pressure and resultant pulmonary hypertension. In patients with constriction, the total cardiac volume is fixed by the rigid pericardium. As a result, there is enhancement of ventricular interdependence and resultant equalization of right and left ventricular diastolic pressures and reciprocal changes in the filling and stroke volume of the right and left ventricles during inspiration (see Pericardial Disease). These reciprocal changes during inspiration can be detected by either echocardiography or cardiac catheterization and are not present in patients with restrictive cardiomyopathy.
How is RCM managed?
Negative chronotropic agents, such as calcium channel blockers and β-blockers, are beneficial, as they lengthen the diastolic filling period and improve myocardial relaxation.
What are a few clinical features of RCM?
Restrictive cardiomyopathy is characterized by severe diastolic dysfunction and, frequently, pulmonary hypertension.
