Chapter 4: Hemodynamics of Pericardial Disease

PATIENT CASE

A 53-year-old man presents with lower extremity swelling, shortness of breath, and abdominal fullness. He has a past medical history of non-Hodgkin lymphoma, hypertension, and gastro­esophageal reflux disease. He previously was treated with chemotherapy and radiation therapy and has been in remission for more than 10 years. Vital signs are heart rate of 110 bpm, blood pressure (BP) of 95/70 mm Hg, respiratory rate of 22 breaths/min, and 92% oxygen saturation on room air. Examination reveals distant heart tones, elevated jugular venous pressure to >15 cm, and clear lungs. There is 2+ pitting edema in the lower extremities with skin discoloration. Abdominal exam has shifting dullness and a tender, palpable liver edge. Chest radiograph shows clear lungs and mildly enlarged cardiac silhouette. Electrocardiogram has nonspecific ST/T changes with varying QRS and low voltages. Emergent bedside echocardiogram is obtained showing large, circumferential pericardial effusion with right ventricular diastolic collapse and significant variation with respiration in the mitral valve inflow velocity. A central venous catheter is placed, and the patient is taken to the cardiac catheterization lab where percutaneous pericardiocentesis is performed, with removal of 500 mL of serosanguinous-appearing fluid. BP improves to 114/82 mm Hg. Examination of the central venous pressure shows continued elevation to a mean pressure of 13 mm Hg with a change in morphology of the waveform after pericardial fluid removal.

PERICARDIAL BACKGROUND

• The pericardium consists of 2 layers that surround most of the heart: the visceral pericardium, which is composed of a single layer of mesothelial cells, and the parietal pericardium, which is mostly acellular and contains collagen and elastic tissue.

• Normally there is <50 mL of fluid in the pericardial space surrounding the heart.

• Pericardium functions to maintain position of the heart, acts as barrier to potential infection, and is innervated with mechano- and chemoreceptors.

• Etiology of pericardial pathology is wide ranging, including infectious, autoimmune, idiopathic, radiation-induced, trauma, neoplastic, and other causes.^1-3

CATEGORIES OF PATHOLOGY

• Acute pericarditis

• Pericardial effusion

• Cardiac tamponade

• Constrictive pericarditis

• Effusive-constrictive pericarditis

HEMODYNAMICS OF PERICARDIAL FUNCTION AND PATHOLOGY

• Normal

  • Pericardial pressure is subatmospheric and tracks with the respiratory cycle. During inspiration, negative intrathoracic pressure in the intrapleural space is transmitted to the structures within the thorax including the pericardial space and cardiac chambers.

  • Reduction in pericardial pressure during inspiration aids in augmenting venous return and diastolic filling in the right side of the heart.

  • Left-sided filling is dependent on pressure gradient from pulmonary veins (PV) to left atrium (LA)/left ventricle (LV).

    • Left heart filling gradient: PV – LV

  • Decrease in intrapleural pressure that occurs during inspiration is better transmitted to the venous system (PVs) than to the left heart; thus, on inspiration, left heart filling pressure is decreased, reducing left heart filling:

    • During inspiration: PV ↓↓ − LV ↓

    • Gradient is reduced, lowering filling pressure

  • Normal pressure-volume curve ...