Pericardium. Pericardial Diseases. Function of Pericardium 10/1/2012

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1 NO LASIX, PLEASE! PERICARDIAL DISEASE IN THE DOG Pericardium Michael Luethy, DVM Diplomate ACVIM Cardiology September 13 th, 2012 Tough, outer, parietal pericardium Delicate, serous, visceral pericardium (epicardium) Space between layers = pericardial cavity Cavity normally contains 0.2 to 0.3 ml/kg of fluid Fluid concentrated in region of heart base Pericardium Pericardium Function of Pericardium Pericardial Diseases Maintains position of heart within the thorax Lubricates the surface of the heart Protects heart from surrounding infection and neoplasia Ventricular diastolic coupling Restrains ventricular filling during periods of volume overload ~ 7% of cardiac cases in the dog Most diseases are acquired and involve increased fluid in pericardial cavity Congenital diseases are uncommon and include: - Peritoneopericardial diaphragmatic hernia (PPDH) - Pericardial cysts - Congenital absence of the pericardium 1

2 PPDH PPDH Weimaraners predisposed Often asymptomatic Clinical signs depend on what organs are displaced and degree of compromise to blood supply Diarrhea, vomiting, anorexia, respiratory abnormalities PPDH Diagnosis Radiographs Clinical signs Muffled heart sounds Radiography Thoracic Ultrasound Enlarged cardiac silhouette Gas pockets noted over the cardiac silhouette Silhouetting of the cardiac and diaphragmatic borders Non-homogenous opacity of cardiac silhouette due to intrapericardial fat Cranial displacement of abdominal organs PPDH PPDH 2

3 Surgical Correction Pericardial Effusion Young animals Animals with associated clinical signs Potential complications include thromboembolic disease and reperfusion syndrome Neoplastic effusions account for 70 to 80% of cases with clinical signs Idiopathic effusion is the most common nonneoplastic diagnosis for pericardial effusion Bacterial, viral, and fungal infections are infrequent causes of pericardial effusion in the dog May be present as a form of bilateral CHF in dogs with severe CDVD Hemangiosarcoma Hemangiosarcoma Reported more frequently than all other tumor types combined Highest incidence in the Golden Retriever Classically arises from the right atrium or right auricle but may originate from any region of the heart Produces effusion primarily through tumor hemorrhage May be a primary or metastatic lesion Extremely aggressive with rapid metastasis Hemangiosarcoma Heart Base Tumor Denotes a location rather than a tumor type The majority of heart base tumors are aortic body tumors (chemodectomas) English Bulldog, Boxer, and Boston Terrier predisposed Tend to be slow growing, slow to metastasize, and locally invasive Effusion is typically related to inflammation and increased fluid production rather than to hemorrhage 3

4 Heart Base Tumor Aortic Body Tumor Ectopic thyroid tumors are the second most common (adenoma or adenocarcinoma) tumor type Adenomas are slow to metastasize but tend to be locally invasive Adenocarcinomas frequently metastasize Effusion related to inflammation rather than hemorrhage Aortic Body Tumor Other Cardiac Neoplasia Mesothelioma arises from the pericardial sac itself and can be extremely difficult to diagnose Lymphosarcoma most frequently leads to diffuse infiltration of ventricular myocardium and may or may not cause effusion Other forms of neoplasia are reported with extremely low frequency Idiopathic Pericardial Effusion Infectious Pericarditis Most common non-neoplastic diagnosis Medium to large breed dogs (> 20 kg) Golden Retrievers Histopathology demonstrates vasculitis and lymphangitis Underlying cause of the inflammation is unknown Common bacterial and viral causes of human pericarditis not identified Autoimmune etiologies have not been confirmed Uncommon in the dog Most frequently associated with migrating foreign bodies (e.g. foxtail awns) May extend from pulmonary infections 4

5 Clinical Signs Clinical Signs Lethargy Syncope Respiratory distress Gastrointestinal signs Abdominal distension passive congestion & ascites May be chronic or acute Relate to the rate of fluid buildup and degree of cardiac tamponade Cardiac Tamponade Cardiac Tamponade Occurs as increasing pericardial pressure begins to interfere with normal filling and function of the heart Tamponade is not an all or none process and begins with relatively small increases in pericardial fluid volumes As intrapericardial pressure exceeds right heart filling pressure (right heart tamponade), signs of exercise intolerance and venous congestion develop As intrapericardial pressure exceeds left heart filling pressure (left heart or biventricular tamponade), cardiac output becomes severely compromised Cardiac Tamponade Cardiac Tamponade The severity of tamponade and circulatory compromise is related to the intrapericardial pressure and not the amount of fluid present A small amount of fluid that accumulates rapidly may cause severe circulatory collapse Slow fluid accumulation allows for pericardial stretch and may lead to > 1 liter of fluid accumulation with few clinical signs Tamponade may occur more rapidly if a patient is already volume depleted The body depends on elevated venous pressures to push blood into the heart during late diastole 5

6 Physical Examination Jugular Distension Muffled heart sounds Abdominal distension Jugular distension Tachycardia Decreased breath sounds ventrally Decreased systemic blood pressure Pulsus paradoxus ECG Electrical Alternans Sinus tachycardia Ventricular arrhythmias Low voltage complexes Electrical alternans Radiography Generalized cardiomegaly Loss of cardiac angles and waists with globoid cardiac appearance Subjective enlargement of caudal vena cava Pleural effusion Pulmonary edema is rare 6

7 Echocardiography Gold standard for documenting effusion and evaluating myocardium and pericardium Small mass lesions are easy to miss on dorsal surface of RA and right auricle Left parasternal view tends to provide a better view of right atrium, right auricle, and heart base Echocardiography Echocardiography - Tamponade Thrombi may be present in the pericardial cavity in the absence of mass lesions Mesotheliomas do not produce defined mass lesions Tamponade may be present without gross diastolic collapse Better visualization of the right atrium and heart base can be obtained with effusion present RA Hemangiosarcoma With Tamponade RA Hemangiosarcoma With Tamponade 7

8 RA Hemangiosarcoma With Tamponade Fluid Analysis Should be performed on all samples Very good for identifying bacterial and fungal infections save sample for culture Rarely able to identify hemangiosarcoma, aortic body tumors, or ectopic thyroid tumors Extremely poor at identifying mesithelioma (false positives & false negatives) Frequently able to detect lymphosarcoma Treatment Treatment The initial measures are aimed at stabilizing patient condition and overall organ perfusion Remember that venous filling pressure must be high enough to push blood into the tamponaded heart Standard cardiac medications (diuretics and vasodilators) lower venous filling pressure NO LASIX PLEASE! IV fluid therapy is indicated if patient cannot have immediate pericardiocentesis Pericardiocentesis is the primary method used for stabilization of the effusion patient with cardiac tamponade Remember that it is easier to visualize the right atrium, right auricle, and heart base with pericardial effusion present Pericardiocentesis Pericardiocentesis Performed in right 5 th, 6 th, or 7 th intercostal space after local anesthesia of the region General anesthesia is rarely needed Left lateral recumbency preferred so that paraconal interventricular branch of left coronary artery is avoided Know peripheral PCV prior to beginning procedure Have ECG running during the procedure Over the needle catheter (14 ga, 5 ½ in, 14 ga, 2 in, or 18 ga, 1.88 in) advanced through skin and intercostal muscles into the pericardial sac 8

9 Pericardiocentesis Pericardiocentesis Catheter advanced and needle withdrawn when a fluid flash is obtained Stop advancement of catheter and needle if cardiac pulsations are felt or ventricular arrhythmias are noted Remove fluid with slow, steady suction to decrease likelihood of irritating epicardial surface Pericardial effusion of almost all etiologies is typically hemorrhagic in appearance Check PCV and monitor fluid for clot formation if unsure about penetration of the catheter into the right ventricle Treatment - Hemangiosarcoma Treatment Other Neoplasia Average survival with no treatment other than pericardiocentesis is 2 weeks Average survival with Adriamycin as a single agent chemotherapy is anecdotally reported as 6 months Surgery does not improve survival over chemotherapy alone unless acute hemorrhage cannot be stopped without amputation of bleeding area Survival time is lower if gross metastatic disease present Administration of yunnan baiyao anecdotally reported to decrease tumor hemorrhage Aortic body or ectopic thyroid tumors can rarely be surgically excised and do not respond well to chemotherapy Pericardiectomy may provide survival times of > 15 months in patients with these tumors Lymphoma and mesothelioma carry a grave prognosis 9

10 Treatment Idiopathic Pericarditis Constrictive Pericarditis Pericardiocentesis alone will be curative in ~ 50% of cases Average time to recurrence is 4 weeks although much longer times may be noted Options for managing recurrent effusion include: - repeat pericardiocentesis alone - repeat pericardiocentesis followed by immunosuppressive therapy with corticosteroids or colchicine and non-steroidal anti-inflammatories - pericardiectomy Results from hypertrophy and fibrosis of the pericardium May develop with chronic or recurrent effusion, infectious etiologies, or other processes Diagnosis is through clinical presentation, echocardiographic findings, and venous pressure wave changes Treatment requires aggressive pericardiectomy 10