- Previous chapters have discussed how fixed obstructions to blood flow through the heart can lead to significant morbidity and mortality. Aortic and mitral stenosis are two examples of lesions, which may prevent the heart from effectively pumping blood. Hypertrophic cardiomyopathy (HCM) likewise can prevent the heart from pumping blood but in a dynamic rather than fixed way. With each beat the hypertrophied septum of the HCM patient together with the anterior mitral valve leaflet prevent the heart from ejecting blood as they obstruct the left ventricular outflow tract (LVOT) (Figure 10–1). Hence, this condition in the past was known as hypertrophic obstructive cardiomyopathy (HOCM). Failure to eject enough blood from the heart leads to syncope, dyspnea, and, at times, sudden death.
- Although rare, cardiac tumors and other masses can interfere with valve function, produce emboli, and dynamically obstruct blood flow through the heart and prevent ejection into the systemic circulation. This chapter will examine these different conditions, which are nonetheless linked by their dynamic ability to prevent the heart from properly functioning.
The midesophageal long-axis view is presented here in outline form. As a consequence of the hypertrophied interventricular septum, flow patterns within the heart are altered such that the anterior leaflet of the mitral valve is drawn during ventricular systole into the LVOT producing obstruction. This is known as systolic anterior motion of the mitral valve (SAM).
HCM is an autosomal dominant trait; roughly one-half of the patients have a blood relative afflicted with HCM.1 The disease can affect both males and females. It is estimated that HCM presents in 1:500 of the general adult population and that these patients are at increased risk for sudden cardiac death (SCD).2 Certainly, many patients with HCM are not detected and can present with SCD as the first manifestation of their cardiac disease.
Symptoms of HCM include: dyspnea, exercise intolerance, palpitations, syncope, chest pain, and SCD. HCM can manifest in both the left and the right heart; however, it is overwhelmingly a disease of the left ventricle. HCM can occur with and without LVOT obstruction.3 In non-obstructive HCM disease the patients develop a hypertrophied myocardium with diastolic dysfunction. As previously discussed in Chapter 2, diastolic dysfunction occurs when the heart is unable to normally relax during diastolic filling. Subsequently, impaired ventricular compliance leads to an increased left ventricular end-diastolic pressure (LVEDP), elevated pulmonary arterial pressures, increased pulmonary congestion, and decreased coronary perfusion pressure ...