Cardio. Pericardial Chap. 45 Flashcards
Pericardial volume:
function:
provides a barrier to infection and inflammation from adjacent tissues and helps balance the output of the right and left ventricles
approximately 0.25 ml/kg body weight of clear, serous fluid normally serves as a lubricant
Hemorr. effusion:
PCV:
ddx (4):
Most sanguineous PCV > 7%, a specific gravity greater than 1.015, and TP > than 3 g/dl
neoplastic, idiopathic, left atrial rupture secondary to severe mitral insufficiency, coagulopathy
Most common hart based tumor:
chemodectoma (aortic body tumor)
arises from chemoreceptor cells at the base of aorta
Other ddx tumors:
pericardial mesothelioma, malignant histiocytosis, some cases of cardiac lymphoma, and occasionally with metastatic carcinoma
Idiopathic pericardial effusion characteristics:
hemorrhagic pericardial effusion
medium to large breed, middle-aged dogs
Cardiac tamponade develops when:
intrapericardial pressure rises toward and exceeds normal cardiac diastolic pressures
RV: 5/24mmHg
external cardiac compression progressively limits right ventricular filling and, with increasing severity, also reduces left ventricular filling
Systemic venous pressure increases and forward cardiac output falls. Eventually, diastolic pressures in all cardiac chambers and great veins equilibrate
reduced coronary perfusion during tamponade can impair both systolic and diastolic function
pulsus paradoxus Inspiration: Left-sided heart filling diminishes why: normally, LV output and MAP \_\_\_\_ during inspiration: preload \_\_\_\_\_:
pulsus paradoxus ____ fall in pressure:
exaggerated respiratory variation in arterial blood pressure
Inspiration - normally lowers intrapericardial and right atrial pressures slightly, which enhances right-sided heart filling and pulmonary blood flow.
Left-sided heart filling diminishes as more blood is held in the lungs and the inspiratory increase in right ventricular filling pushes the interventricular septum leftward
Thus left-ventricular output and systemic arterial pressure normally decrease slightly during inspiration
lowers RA pressures, enhancing right-sided heart filling
Pulsus paradoxus is an exaggeration of this normal pressure difference with respirations; patients with pulsus paradoxus exhibit a fall in arterial pressure during inspiration of 10 mm Hg or more
CT vs echo for dx mass:
ability to diagnose the presence of a cardiac mass with CT has not yet been shown superior to echocardiography
Cardiac tamponade CVP:
normal:
conversion:
> 10 to 12 cm H2O
0-8 cm H2O
x 0.73 (1 mmHg = 1.36 cm H20)
pericardial pH:
neoplastic (and other noninflammatory) > pH of 7.0
inflammatory effusions generally < pH
However, there is too much overlap for pericardial
effusion pH to be a reliable discriminator
Pericardial procedure:
- skin is shaved & surgically prepared over right precordium,
- 3-7th intercostal spaces, sternum to costochondral junction
- Local anesthesia, small stab incision
- using a larger catheter system, 14g 4inch puncture site should be just cranial to a rib
- once the needle has penetrated the skin, should apply gentle negative pressure, flash, 2mm feed off
- aim the needle tip toward the patient’s opposite shoulder. The pericardium causes increased resistance to
needle advancement and may produce a subtle scratching sensation when contacted - extension tubing is attached to the catheter
pericardial fluid samples are saved in sterile EDTA and clot tubes for evaluation
a few drops can be placed on the table or into a clot tube and a sample spun in a hematocrit tube
supernatant appears yellow-tinged (xanthochromic)
Recurrent effusion tx:
subtotal pericardiectomy, removal of the pericardium ventral to the phrenic nerves allows pericardial fluid drainage to the larger absorptive surface of the pleural space
less invasive techniques of thoracoscopic partial pericardiectomy or percutaneous balloon pericardiotomy are also used successfully to treat idiopathic
Survival time mesothelioma
longer than in those with HSA, but the overall prognosis is poor
Heart base tumors (e.g., chemodectoma) tend to be slow growing and locally invasive and have a low metastatic potential. Partial pericardiectomy may prolong survival for years.
CONGENITAL PERICARDIAL DISEASE
Peritoneopericardial diaphragmatic hernia (PPDH)
CS:
most common pericardial malformation in dogs and cats
Abnormal embryonic development (probably of the septum transversum) allows persistent communication between the pericardial and peritoneal cavities at the ventral midline
diagnosed during the first several years of life, usually
after gastrointestinal or respiratory signs develop Vomiting, diarrhea, anorexia, weight loss, abdominal pain, cough, dyspnea, and wheezing are common signs.
PE: include muffled heart sounds on one or both sides of the chest, a weak or displaced cardiac precordial impulse, an “empty” feel on abdominal palpation
Diagnosis
Thoracic radiographs are often diagnostic or highly suggestive of PPDH. An enlarged cardiac silhouette, dorsal tracheal displacement, overlap of the diaphragmatic and caudal heart borders, and abnormal fat or gas densities within the cardiac silhouette are characteristic
Echocardiography may confirm the diagnosis when radiographic findings are equivocal. Other imaging techniques can also be used.
Treatment
Therapy involves surgical closure of the peritoneal-pericardial defect after viable abdominal structures are returned to their normal position.
The presence of other congenital abnormalities and the animal’s clinical signs influence the decision to operate. In uncomplicated cases prognosis is excellent; however, perioperative complications are common and, although often mild, can include death. Older animals without clinical signs may do well without surgery.
