VETgirl December 2024 BEAT e-Magazine

QUARTERLY BEAT / DECEMBER 2024

REFERENCES

Comprehensive echocardiographic assessment of the heart can be conducted if the patient is more stable prior to pericardiocentesis, as the presence of pericardial fluid facilitates the visualization of intra-pericardial masses. However, it is imperative that the patient’s safety not be compromised by delaying the removal of the fluid or by trying to obtain a formal echocardiogram (especially if the patient is not stable). Often, a small amount of effusion remains after pericardiocentesis, aiding in the identification of tumors. Tamponade, which should be diagnosed through clinical examination in any patient showing signs of shock and pericardial effusion, can also be supported by cardiac POCUS. The "trampoline" sign (seeing the right atrium or ventricle bend or deform), indicating right atrial and ventricular collapse, can be seen in both right parasternal long and short- axis views, though it is usually easier to observe in the right parasternal four-chamber long-axis view. TREATMENT: 1. IV fluids: Cardiac tamponade results from inadequate diastolic filling and therefore is different than left-sided congestive heart failure. Administering IV fluids (initially as a challenge with a fluid bolus) to improve diastolic filling can be considered (and is the authors’ preference) until pericardiocentesis can be performed. 2. Pericardiocentesis: Pericardiocentesis is a lifesaving procedure essential for the rapid stabilization of dogs. Indwelling pericardial catheters, which can be quickly placed and are a safe alternative to pericardiocentesis using needles or single tap catheters, require minimal sedation and are not associated with a higher rate of complications. They can be advantageous as they allow for serial drainage if pericardial effusion recurs. In cats, pericardial effusion is most commonly associated with congestive heart failure, is generally well tolerated, and often responds to heart failure management. 3. Other: Following pericardiocentesis, treatment may include surgery, pericardiectomy, chemotherapy, or radiation therapy for heart base, atrial, or intracardiac tumors, as well as antibiotics for infectious pericarditis. Doxorubicin-based chemotherapy has been reported as a viable treatment for dogs with right atrial masses and pericardial effusion. For persistent or recurrent pericardial effusion, pericardiectomy (via thoracotomy or thoracoscopy) or balloon pericardiotomy remains the treatment of choice. Approximately 40% of benign effusions resolve spontaneously after one or two pericardiocentesis procedures.

2. TRANSTHORACIC POCUS (FIG. 2) Position the ultrasound transducer directly over the heart on either or both sides of the chest to assess for pericardial effusion (most often right transthoracic). Care must be taken to differentiate the right ventricle and other cardiac chambers from pericardial effusion. Pericardial effusion appears as a lucent (most often hypoechoic) area surrounding the heart. Increasing the depth of the ultrasound beam allows visualization of the entire left ventricular apex and surrounding structures. When pericardial effusion is present, the heart will completely be encircled by a circumferential ring of fluid, outlined by the bright white pericardium. Be sure to extend the depth to ensure the entire heart AND pericardium are visible when using this window.

3. PERICARDIO-DIAPHRAGMATIC WINDOW (FIG. 3)

Located by sliding the transducer caudal to the heart or identifying the curtain sign (caudal lung and pleural space border seen as a vertical edge artifact created by air-filled lung overlying soft tissue structures of the abdomen) and tracing it ventrally. This window allows the caudal portion of the heart (specifically the left ventricular wall) to be seen alongside the diaphragm in the same image. This site is useful for differentiating between pericardial effusion, which conforms to the heart's contours and curves away from the diaphragm, and pleural effusion, which follows the diaphragm and forms a triangular or sharp point as it fills the costophrenic recess.

1. Côté E, Schwarz LA, Sithole F. Thoracic radiographic findings for dogs with cardiac tamponade attributable to pericardial effusion. J Am Vet Med Assoc 2013 Jul 15;243(2):232-5. 2. Ghaffari S1, Pelio DC, Lange AJ, et al. A retrospective evaluation of doxorubicin-based chemotherapy for dogs with right atrial masses and pericardial effusion. J Small Anim Pract 2014 May;55(5):254-7. 3. Hall DJ1, Shofer F, Meier CK, Sleeper MM. Pericardial effusion in cats: a retrospective study of clinical findings and outcome in 146 cats. J Vet Intern Med 2007 Sep-Oct;21(5):1002-7. 4. Fahey R, Rozanski E, Paul A, Rush JE. Prevalence of vomiting in dogs with pericardial effusion. J Vet Emerg Crit Care (San Antonio) 2017 Mar;27(2):250-252. 5. Cook S, Cortellini S, Humm K. Prospective evaluation of pericardial catheter placement versus needle pericardiocentesis in the management of canine pericardial effusion. J Vet Emerg Crit Care (San Antonio) 2021 Jan;31(1):11-17. 6. Cook S, Cortellini S, Humm K. Retrospective evaluation of pericardial catheter placement in the management of pericardial effusion in dogs (2007-2015):18 cases. J Vet Emerg Crit Care (San Antonio) 2019 Jul;29(4):413-417.

Figure 3: The pericardio-diaphragmatic (PD) window is identified when the transducer is positioned perpendicular to the ribs, marker directed cranially and situated where the heart and the diaphragm are visible within the same sonographic window. It is easy to locate by either sliding the transducer caudally off the heart or locating the curtain sign in the mid thoracic region and following it ventrally until both the diaphragm and heart are visible within the same sonographic image. It should be the only site on the hemithorax where the diaphragm is visible, curving away from the thoracic wall due to the cardiac notch and the presence of mediastinal tissue and fat (MT). The PD window is a good site to differentiate pericardial and pleural effusions. RVL; right ventricular lumen, IVS; intraventricular septum, LVL; left ventricular lumen, LVFW; left ventricular free wall, GB; gall bladder, SC; subcutaneous tissues. Image courtesy Calgary VPOCUS Academy, with permission.

WEBINAR HIGHLIGHTS

Figure 2: Image of a dog depicting transducer location and a radiograph with schematic representation of the right parasternal short axis windows obtained and appearance of pericardial effusion. Images courtesy Calgary VPOCUS Training Academy and Lindsey Strang, with permission.

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