12

12 CASE 12


A 73-year-old man comes to the emergency department complaining of chest pain, shortness of breath on exertion, and syncope.


The patient has poorly managed hypercholesterolemia and a 10-year history of hypertension.



PHYSICAL EXAMINATION



VS: T 37°C, P 85/min, R 18/min, BP 100/75 mm Hg

PE: A systolic murmur is present, loudest over the aorta and peaking at mid systole. Palpitation of the carotid upstroke reveals a pulse that is both decreased and late relative to the apical impulse. Palpation of the chest reveals an apical impulse that is laterally displaced. Lungs are clear, and there are no rales.


LABORATORY STUDIES



ECG: Left axis deviation but no abnormalities in the ST segment.

Chest radiography: Enlarged left ventricle and calcification of the aortic valve

Doppler ultrasonography: A greatly increased velocity of flow during the systolic portion of the cardiac cycle. The left atrium and left ventricle chambers are enlarged, and left ventricular hypertrophy is present.

Cardiac enzymes: CK-MB, troponin I, and myoglobin levels are normal.


DIAGNOSIS


Aortic valve stenosis



PATHOPHYSIOLOGY OF KEY SYMPTOMS


The normal function of the aortic valve is to isolate the aortic and left ventricular chambers during ventricular diastole and to open so as not to impede ventricular ejection during ventricular systole. Aortic valve stenosis is a narrowing of the aortic valve so that ventricular ejection is impeded. Aortic stenosis often occurs as a result of calcium deposits on the leaflets of the aortic valve (see Fig. 9-1, p.31).


The symptoms are due to an impaired ability to eject blood from the left ventricle into the aorta. Impaired ventricular ejection, combined with the normal inflow of blood from the left atrium, results in an increased volume in the left ventricle during diastolic filling. The increase in preload causes an increase in left ventricular pressure generation during systole. The increased left ventricular systolic pressure can overcome the resistance caused by the stenotic aortic valve, which allows a partial recovery of left ventricle cardiac output. In patients with this disease, left ventricular systolic pressures are much higher than aortic systolic pressures and there is a pressure gradient across the aortic valve throughout systole (Fig. 12-1).


image

FIGURE 12–1 Aortic stenosis is characterized by an abnormal left ventricular (LV)-to-aortic pressure gradient (shaded area). LA, left atrium.

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Jul 4, 2016 | Posted by in PHYSIOLOGY | Comments Off on 12

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