Ch 107 Pericardial surgery Flashcards
What are the 2 layers of the pericardium?
Outer fibrous layer
Inner serous layer (closed mesothelial lined sac with parietal and visceral layers)
anatomy
- envelopes the heart; root of the aorta and pulmonary artery; and termination of the venae cavae, pulmonary veins, and azygos vein.
- visceral layer of serous pericardium known as the epicardium.
- The epicardium is attached firmly to the myocardium
- caudoventral apex of fibrous pericardium anchors ventrally at the muscular insertion of the diaphragm (sternopericardiac ligament)
- pericardium is supplied by paired pericardial branches of the internal thoracic arteries
List the functions of the pericardium
- Keeps the heart in position
- Restrains cardiac filling
- Enhances diastolic ventricular couplig
- Protects against atrial rupture
- Prevent spread of infection or neoplasia to heart from pleural cavity
- Provides a gliding surface for heart motion
pericardium is noncompliant and has a small reserve volume, intrapericardial pressure rises rapidly when the volume of its contents increases acutely.
With slow accumulation, the pericardium stretches
What does pericardial fluid contain?
What is a normal volume?
Pericardial fluid is an ultrafiltrate of the serum
- phospholipids for lubrication
- Protein 1.7-3.6g/dL
- Colloid osmotic pressure approx 25% of serum
Normal volume 1-15ml
What are the physiologic effects of cardiac tamponade? (7)
- Decreased cardiac output
- Increased central venous pressure
- Activation of compensatory RAAS and sympathetic adrenomedullary catecholamine release
- As atrial wall stretching is limited, atrial natriuretic peptide is not produced and therefore does not counteract effects of RAAS
- Increase in systemic venous and portal pressures causing jugular vein distention, liver congenstion, ascites and peripheral oedema
- Compression of coronary arteries causes poor myocardial perfusion
- Cardiogenic shock and death
cardiac tomponade
Cardiac tamponade:
Increased pericardial pressure → increased diastolic pressure → reduced stroke volume
- pericardial pressure = right ventricular filling pressure (R-sided tamponade)
→ left ventricular filling pressure (L-sided tamponade)
→ decreased cardiac output, increased systemic venous pressure
→ activation of RAAS → Na+ and H2O retention
+ sympathetic stimulation/catecholamine release → +ve ino- + chronotropic effects and vasoconstriction
- no atrial wall stretch → no atrial natriuretic peptide → no counteracting RAAS effects
→ increased systemic venous and portal pressure
→ jugular vein distension, liver congestion, ascites, peripheral oedema
+ compression of coronary arteries → myocardial hypoxia/ischemia
+ decreased cardiac output and arterial hypotension → cardiogenic shock → death
What is pulsus paradoxus?
variations of pressure quality associated with respiration phase
A variation in systolic arterial pressures up to 10mmHg from increasing venous return during inspiration in a relatively nonexpandable heart (due to pericardial effusion) causing intraventricular septal shift to the left, reducing CO
Can also be seen with obstructive lung disease, restrictive cardiomyopathy or hypovolaemic shock and is therefore not pathognomonic for pericardial effusion
Pulsus paradoxus:
Paradoxical arterial pressure variation during severe cardiac tamponade
Inspiration → decreased pericardiacl pressure and right ventricular pressure
→ venous return to right atrium, ventricle and pulmonary flow
- heart volume limited by pericardium – left intraventricular septum shifts to left
→ decreased left ventricular EDV, left heart output and arterial pressure
→ variation in systolic arterial pressure
What is the risk associated with partial pericardial defects?
Cardiac herniation
What have pericardial cysts been associated with?
PPDH
Other cases have been on a stalk at the apex of the pericardium
Suggests they result from entrapment of omentum, falciform ligament or liver in pericardium during development
What 2 syndromes can be associated with pericardial rupture?
pathophys
During healing, a stricture can develop causing vena caval compression
- Budd Chiari Syndrome: ascites and hepatomegaly
- Caval syndrome: Swelling of head and neck
Caval angiography for diagnosis. RIght 5/6th IC thoracotomy for resection of fibrotic sac +/- angioplasty with pericardial patch graft
severe ascites
rupture Tx
- caudal vena cava may appear to be kinked
- Caval angiography for diagnosis.
- RIght 5/6th IC thoracotomy for resection of fibrotic sac +/- angioplasty with pericardial patch graft
Pericardial Effusion
Etiology
- transudative: congestive heart failure, peritoneopericardial diaphragmatic hernia, hypoalbuminemia, or increased vascular permeability
- exudate: infectious or noninfectious pericarditis
- hemorrhagic: trauma, neoplasia, anticoagulant intoxication, or rupture of the left atrium secondary to mitral valve disease, idiopathic
What are the most common neoplastic causes of pericardial effusion?
HSA of right atrial appendage
Chemodectoma, usually along ascending aorta (brachycephalics most common)
mesothlioma (difficult to distinguish from idiopathic)
What breed is overrepresented for pericardial effusion?
Golden retreiver
What is an expected central venous pressure of a dog with pericardial effusion?
- Classic findings: muffled heart sounds, weak femoral pulses, tachycardia, and distention of jugular and peripheral veins.
- Chronic: CHF and acities
- acute manifestation because of acute bleeding
With cardiac tamponade, central venous pressure frequently exceeds 10 to 12 mm Hg
Describe the following ECG
Electrical alternans
- Amplitude of QRS and ST-T complexes changes from 1 complex to another due to heart swinging in fluid filled pericardial sac
- Strongly suggestive of pericardial effusion
Pericardial Fluid Cytology and Analysis
- usually do not differentiate the underlying cause
- serosanguineous pericardial effusions are rapidly depleted of clotting factors, fluid samples will not clot in an activated clotting time tube unless active hemorrhage is present
- cytology not reliable to dx neoplasia
What is the sentivity and specificity of echocardiogram for cardiac mass detection?
Neither CT/MRI found to improve detection of cardiac masses.
82 and 100%
- anechoic space between the epicardium and pericardial sac
- Collapse of the right atrium or ventricle during diastole
- allows visualization of cardiac masses or myocardial infiltration
RADS
- With chronic effusion and pericardial distention, the cardiac silhouette becomes globoid in shape
- pleural effusion, which often accompanies pericardial effusion
What can be measured in the plasma of dogs with pericardial effusion which is assoc with HSA?
Cardiac troponin I
- Conc over 0.25ng/ml 82% senstivite and 100% specific for cardiac HSA
Where do you perform a pericardiocentesis?
ECG > touche myocardium, premature complex will occur
Right 5/6th ICS with a 20g needle/catheter
pericardiocentesis - complications
adverse events in 10%:
- dysrhythmias,
- cardiopulmonary arrest
- continued bleeding
Blood vs effusion: effusate should not clot, and its PCV «_space;peripheral blood
20 g needle, extension set, three-way stopcock, and large syringe.
What are the surgical options for pericardial effusion? (4)
Pericardiectomy
- Subtotal or complete (complete does not improve outcomes)
- through a median sternotomy or ICT
Thoracoscopic pericardial window
- 3x3cm window in large breed dogs (too large risk cardiac herniation)
- Transdiaphragmatic (subxiphoid with right 4th and 7th ICS or right and left 7th ICS) or intercostal approach
- biopsy masses
Thoracoscopic subtotal pericardiectomy
- Transdiaphragmatic approach with instrument cannulas in left and right 9th ICS
Percutaneous Balloon Pericardiotomy
pericardectomy
- can be curative for idiopathic pericardial effusion and possibly palliative for neoplastic
- decreases the surface area of pericardium, thus reducing fluid production
- increases the surface area for absorption by allowing fluid into the pleural cavity
What is the prognosis for pericardial effusion?
- neoplastic, idiopathc, pericardiocentesis, pleural effusion
Neoplastic:
- HSA MST 16d
- Aortic body tumours, MST 730d with Sx vs 42d
- Mesothelioma usually deveolps unremitting pleural effusions 1.5-5m post pericardiectomy. MST 10.5-13.6m
Idiopathic
- Excellent
- Subtotal pericardiectomy 100% surviva at 3yr (Dunning et al)
- Another study 12% dies periop, 16% died within 1 yr, 72% long term survival
- Pericardial window MST 13.1m, 35% survival at 3yr
- MST 22m
pericardiocentesis ONLY
- outcome is variable
- 9 of 14 dogs (one to three treatments), most alive follow-up 3 years late
- palliative for HSA
pleural effusion
- most common complication undergoing pericardiectomy
- if lasts > 30 days, more likely to have a poor prognosis
Constrictive Pericarditis
- Chronic inflammation of the pericardium results in extensive fibrous tissue proliferation and pericardial thickening.
- Severe lesions can constrict the heart, which compromises cardiac filling and CO
- caused by any condition that results in chronic pericarditis.
pathophys
- noncompliant pericardium abruptly limits ventricular filling and produces near equilibration of all cardiac chambers. As the condition worsens, cardiac output declines
- RCHF from activation of the RAAS
What is the Kussmaul sign?
Paradoxical, persistent increase in jugular venous pressure during inspiration
- Assoc with constrictive pericarditis
- Negative intrathoracic pressure during inspiration is not transmitted to the cardial chambers
How is restrictive pericarditis diagnoses?
Cardiac catheterisation
- Measurement of pulmonary capillary wedge, atrial and ventricular pressures
- Increased and equilibration or near-equilibration of diastolic filling pressures in all chambers
What is the Tx and prognosis for constrictive pericarditis?
Subtotal pericardiectomy
- Relieved clinical signs in 6/10 dogs
- Prognosis more guarded if epicardium involved - required decortication
- Prognosis poor if develops after treatment of pericardial effusion
The development of ventricular fibrillation as a
complication of pericardiectomy in 16 dogs
Raleigh 2022
kuntz
Retrospective, multi-institutional study
Surgical approaches included thoracoscopy (12), intercostal
thoracotomy (3) and median sternotomy (1). Electrosurgical devices were used
to complete at least part of the pericardiectomy in 15 of 16 dogs. Ventricular
fibrillation appeared to be initiated during electrosurgical use in 8/15 dogs
14 of 16 dogs died from intraoperative VF
incidence of VF approximately 3% of dogs undergoing pericardiectomy
In most dogs ventricular fibrillation was a fatal complication of
pericardiectomy. Ventricular fibrillation might be associated with the use of
electrosurgical devices and cardiac manipulation
cardiac compressions
Defibrillation was attempted in 13/16 dogs
Three dogs were successfully
converted to a sinus rhythm
Three distinct mechanisms for electrosurgical induction
of VF have been established
- high current stimulus that occurs during the T wave
of a cardiac cycle and immediately induces VF
- multiple electrical
pulses of a lower current applied over 1-5 s to epicardial
cells
- The final mechanism involves an even
lower current applied over 90-300 s, which also causes an
increase in heart rate. Values greater than 220 BPM
decrease the diastolic filling time
Systematic review of the treatment options for pericardial
effusions in dogs
Logan M. Scheuermann 2021
Most articles included were case studies
(68.2%) or retrospective case series (25.2%), with all articles providing a low
level of evidence.
variability of the outcomes
not sufficient evidence to recommend one treatment option rather than another.
idiopathic pericarditis/pericardial effusion
→ long-term survival with pericardectomy
- difference between subtotal pericardiectomy and thoracoscopic window uncertain
neoplastic pericardial effusion
→ no prolongation of MST or DFI after sx vs conservative (hemangiosarcoma or
mesothelioma)
- when cardiac mass was present – pericardiectomy resulted in less recurrence of CS
- no difference between subtotal pericardiectomy and thoracoscopic window
- Medications Yunnan Baiyao, aminocaproic acid, and chemotherapies, have been used in attempt to prolong MST of neoplastic
pericardial effusions without clear benefit
dogs in which a subtotal pericardiectomy was performed had longer survival time and DFI than those that underwent a thoracoscopic pericardial window > quality of evdience low
complere exmaination at time of surgery recommened heart and pericardium in surgery to rule out neoplasia may be of benefit to draw conclusions about survival outcomes
Outcomes of dogs with recurrent idiopathic pericardial effusion
treated with a 3-port right-sided thoracoscopic subtotal
pericardiectomy
Kurt P. Michelotti 2019
Retrospective case series.
Animals: Sixteen client-owned dogs.
Thoracoscopic subtotal pericardiectomy can be readily performed
with only 2 instrument ports, both on the same side of the dog, and without 1-lung
ventilation.
no surgical complications. The median duration of postoperative
follow-up was 191.5 days (range, 5–1345). The median survival time (MST) after
surgery was 365 days (range, 5–1345); MST of dogs with a histopathological diagnosis
of neoplasia (n = 4) was 76 days, whereas dogs with no evidence of neoplasia
had an MST of 367 days (n = 12, P = .14). Recurrent pleural effusion was the
ultimate cause of death or reason for euthanasia in 8 of 16 dogs.
Outcome in dogs with presumptive idiopathic pericardial effusion
after thoracoscopic pericardectomy and pericardioscopy
Carvajal 2019
Multi-institutional retrospective study (2011-2017).
Animals: Eighteen dogs
Nine dogs had pericardioscopic abnormalities
consistent with masses, nodules, or adhesions. Median survival time (MST) for the
9 dogs with abnormalities identified by pericardioscopy was 66 days, whereas
MST for the 9 dogs with unremarkable pericardioscopic examination results was
not reached (P = .0067). Median survival time for dogs based on histopathologic
diagnosis alone was not different between dogs with a diagnosis of neoplasia and
dogs with a diagnosis of pericarditis
Thoracoscopic pericardectomy/pericardioscopy and targeted
biopsy of the pericardium and pleura are recommended in dogs with echocardio
graphic
idiopathic pericardial effusion
Epicardial exposure provided by a novel thoracoscopic
pericardectomy technique compared to standard pericardial
window
Laura A. Barbur 2018
describe a novel technique for thoracoscopic pericardectomy using
a pericardial window with vertical pericardial fillets (PW1F). (2) To compare epicardial
exposure between a standard pericardial window (PW) and PW1F.
