9

9 CASE 9


A 45-year-old man comes to the emergency department complaining of sharp, stabbing chest pain beneath the sternum.


The patient is anxious, and his cognitive abilities are slightly impaired. The pain is relieved by sitting upright. He has a dry cough and is recovering from an upper respiratory tract infection.



PHYSICAL EXAMINATION



VS: T 38.5°C, P 85/min, R 22/min and shallow, BP 105/55 mm Hg during expiration and 90/40 mm Hg during inspiration (pulsus paradoxus). Jugular veins are distended and enlarge during inspiration (Kussmaul sign).

PE: All heart sounds are muffled. A pericardial rub can be heard on the lower left sternal border.


LABORATORY STUDIES



Echocardiogram: Enlargement of the heart

ECG: Normal sinus rhythm with no abnormalities

CK-MB: Normal troponin I and myoglobin levels

CBC: Elevated white blood cell count


DIAGNOSIS


Pericardial tamponade



COURSE


Pericardiocentesis was performed under echocardiographic guidance. Symptoms were relieved with removal of 300 mL of fluid. The patient was admitted to the hospital for treatment and observation.



PATHOPHYSIOLOGY OF KEY SYMPTOMS


Preload is one of the main determinants of cardiac output. It is the volume of blood in the ventricle before ventricular contraction. Left ventricular end-diastolic volume, left ventricular end-diastolic pressure, and the “upstream” pressures in the left atrium, pulmonary vein, or pulmonary capillary all provide useful indices of left ventricular preload.


Ventricular filling occurs at low pressures (5 to 10 mm Hg), in contrast to the high pressures (120 mm Hg) generated by the left ventricle during systole. The low filling pressures mean that ventricular filling can be impaired by a relatively low pressure external compression (Fig. 9-1).


image

FIGURE 9–1 Events of the cardiac cycle for left ventricular function, showing changes in left atrial pressure, left ventricular pressure, aortic pressure, ventricular volume, the electrocardiogram, and the phonocardiogram.

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Jul 4, 2016 | Posted by in PHYSIOLOGY | Comments Off on 9

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