Our patient has hypertrophic obstructive cardiomyopathy and that was clearly reflected on the bedside examination. When we felt the carotid arterial impulse we found it to be rapid rising and twice beating, or bifid, with two impulses in systole. The is only found in a limited number of circumstances, in this disorder and also in patients who have aortic regurgitation with or without an element of aortic stenosis. When the latter diagnoses are considered, one would anticipate finding the blood pressure to have a wider pulse pressure. In our case, the blood pressure and pulse pressure were normal.
We then went on an evaluated the chest wall. We found, not only was it enlarged, reflecting an hypertrophied left ventricle, but we also found that there was a peculiar and unusual contour to that left ventricular impulse. First, we felt a palpable fourth heart sound, reflecting the lack of compliance of the ventricle, as the atrium pushes blood into the ventricle in presystole. And then we felt a bifid pulse at the apex in systole, that is, two systolic impulses. That is essentially diagnostic of hypertrophic obstructive cardiomyopathy, and it occurred because this dynamic obstruction occurs during ejection in systole as the ventricle contracts and also explains the reason for the bifid impulse in the carotid vessel.
The we listened to patient. When we listened at the upper left sternal edge, we focused on the second heart sound, and we heard paradoxic splitting of those sounds. When the patient breathed in, the second sounds were single and when the patient breathed out, it was [sounds]. That paradoxic splitting in our patient is due to the outflow tract obstruction that delays left ventricular ejection, so that the aortic valve closes later. And then, we focused on the murmur, especially at the lower left sternal edge. While that murmur was present higher up at the upper right and left sternal edge, it was most intense at the lower left sternal edge. That murmur was crescendo-decrescendo, typical of the configuration found when there is obstruction to outflow from the ventricle, and it was lower down on the chest, as one might anticipate because that obstruction was below the aortic valve. And then we listened at the apex and we found two important findings: 1) filling sounds, the fourth sound and the third sound, again, reflecting the poor compliance of the ventricle during periods of flow into the ventricle due to atrial contraction in the case of the fourth sound, and the large amount of flow that occurs in early diastole in terms of hearing a third sound. And we heard a murmur, but the murmur was quite different than the ejection, or crescendo-decrescendo, murmur heard at the lower left sternal edge. The murmur at the apex was higher in frequency, it was holosystolic, and that murmur is the type of murmur you hear with mitral regurgitation and mitral regurgitation is often associated with hypertrophic obstructive cardiomyopathy, because of dysfunction of the mitral apparatus.
This is a magnificent example of a case where our bedside skills alone have very elegantly defined the diagnosis and our diagnosis is hypertrophic obstructive cardiomyopathy.
HOCM discussion
In patients with hypertrophic obstructive cardiomyopathy the degree of outflow obstruction may vary, resulting in changes in the intensity of the murmur. The degree of apposition of the ventricular septum to the anterior mitral valve leaflet and, hence, the outflow tract obstruction, is affected by ventricular volume, or preload, ventricular pressure, or afterload, and by contractility.
HOCM animation
An increase in volume, or preload, reduces the obstruction and the murmur, as does an increase in pressure, or afterload. An increase in contractility increases the obstruction and the murmur.
Our patient vs. majority
The key to defining the diagnosis of hypertrophic obstructive cardiomyopathy in our patient was the recognition of the classic history and physical findings. The majority of patients with this lesion, however, may be entirely asymptomatic or have few or no diagnostic bedside findings.
Findings
Often, the only physical finding suggesting the presence of obstruction in patients with hypertrophic obstructive cardiomyopathy is the systolic crescendo-decrescendo ejection murmur. The intensity of this murmur may be enhanced by bedside maneuvers that decrease left ventricular volume or pressure. These include having the patient perform the Valsalva maneuver or stand from the squatting position.
Valsalva
The Valsalva maneuver consists of a forced expiration against a closed airway. This markedly increases intrathoracic pressure, decreasing venous return. The resultant decrease in left ventricular volume results in an increase in intracavitary obstruction and tends to increase the murmur of hypertrophic obstructive cardiomyopathy, while it decreases the murmur of valvular aortic stenosis.
Squatting → standing
Squatting increases pressure, or afterload, by partially obstructing the large vessels to the lower extremities, reducing the murmur of hypertrophic obstructive cardiomyopathy. Standing from the squatting position decreases venous return, or preload, increasing the murmur.