Blunt cardiac injury Flashcards
(48 cards)
What is the definition of blunt cardiac injury?
cardiac injury that results from impact of a body surface against a blunt surface OR impact of an object with blunt surface against the body
BLI refers to cardiac injury resulting from blunt trauma.
What are common causes of blunt cardiac injury?
- Motor vehicle trauma
- Fall from height
- Kicks from humans/livestock
Name 5 other reasons apart from cardiac injury as cause of arrhtyhmias in patients sustaining BCI
- acid-base disturbances
- anaemia secondary to hemorrhage
- concurrent neurologic injury
- electrolyte derangements
- shock
What factors can lead to blunt cardiac injury without overt evidence on PE?
- Elastic nature of thorax
- indirect trauma through:
- sudden incrase in preload + overdistension of cardiac chambers following impact to the extremities or abdomen
- acceleration/deceleration forces of extremities/head/abdomen that are translated to the thorax
What are the 7 mechanisms of blunt cardiac injury?
- Direct impact in end-diastole (ventricles max capacity) or end-systole (atria max capacity)
- Suddenly increased cardiac preload due to increased venour return from impact on peripheral or abdominal veins
- Bidirectional forces compressing the heart
- Acceleration and deceleration causing myocardial damage/rupture, damage to great vessels and coronary arteries
- Blast forces causing cardiac contusion/rupture
- Concussive forces leading to arrhythmias
- Cardiac penetration by displaced fractures
Within what timeframe do most clinically significant arrhythmias occur in BCI?
≤ 24 hr of hospitalization
Name 7 clinical complications that may require intervention in BCI
- VT
- SVT
- Bradyarrhythmias
- Hemopericardium
- Hemothorax
- Traumatic pericardial hernia
- Cardiac decompensation with poor CO or CHF
What physical examination findings indicate possible cardiac injury?
- VPCs
- Tachycardia
- Bradycardia
- Muffled heart sounds (effusion)
- Jugular pulsation + distension (pericardial effusion, right heart dysfunction through contusions, right-sided valve rupture)
- New onset heart murmurs (valve rupture/insufficiency, septal rupture + intracardiac shunting)
- Displacement of heart sounds (Effusion, cardiac herniation via pericardial rupture)
- positional changes of BP or borborygmi in chest –> traumatic peritoneopericardial diaphragmativ hernia
What are the most common and clinical relevant arrhythmias in BCI?
Ventricular arrhythmias due to myocardial contusions
What is the prevalence of ventricular arrhythmias in dogs with blunt cardiac injury on admission? How does this change on continuous ECG? What is the prevalence of clinically significant ventricular arrhythmias that require treatment?
admission: 13-17%
continuous: 96%
treatment: 11-16%
What is the significance of cardiac troponin I in blunt cardiac injury?
Released following myocardial damage –> evaluate risk for arrhythmias
What does a normal cTnI level (0-0.11 ng/ml) indicate in context of BCI?
100% negative predictive power when combined with baseline ECG
What is a possible reason for nonhemorrhagic pleural/pericardial effusion (modified transsudate) post BCI?
cardiac dysfunction secondary to myocardial contusion and/or valve rupture + new insufficiency with VO
When should echocardiography be considered in blunt cardiac injury?
- New-onset murmur
- Unexplained poor CO
What is the primary treatment goal for blunt cardiac injury? What are treatments that can be instigated?
- Supportive care to target adequate perfusion and CO
- analgesia
- fluid therapy
- sedation for respiratory distress (opioids +/- benzos)
- judicious use of diuretic therapy if needed due to concern over renal perfusion
- anitarrhythmics if CV significant arrhythmias present
What conditions can potentiate arrhythmias and CV instability in BCI?
- Anemia
- Hypoxemia
- Electrolyte derangement
- Tissue hypoxia
- Pain
What is the first-line treatment for sustained ventricular arrhythmias in dogs?
- Sodium channel blockers = Vaughn Williams class I
- Lidocaine 2mg/kg IV OR (up to 3 boluses + total dose of 8mg/kg with 3-5min between boluses) followed by CRI 50-100 mcg/kg/min
- Procainamide 2-8 mg/kg IV over 3-5min (up to 16mg/kg total) followed by CRI 25-40 mcg/kg/min
What are the signs that indicate the need for antiarrhythmic treatment in dogs?
- Sustained ventricular arrhythmias for 15-30s >150 bpm for dogs or >250 bpm for cats OR
- sustained VA >180 bpm for shorter duration
- Associated with hemodynamic consequences
- R on T
- multiform
What is the first-line treatment for supraventricular tachycardia? What is the second-line?
1st line:
Diltiazem: calcium channel blocker (Vaughn Williams class IV) –> 0.25mg/kg IV over 2min
additional 0.25mg/kg IV boluses q15min until conversion to normal SR OR maximum dose 0.75mg/kg
2nd line: Esmolol = ultra-short acting b-blocker (Vaughn Williams class II) –> 0.05´0.1mg/kg IV q5min up to max 0.5mg/kg OR
Propranolol 0.02-0.06 mg/kg IV q8hr (longer duration - hard to titrate)
What should be done for hemodynamically significant bradyarrhythmias? Which bradyarrhythmias might that be?
Pacemaker therapy
High-grade 2nd (> 2:1 non-conducted P waves) or 3rd AV block
Fill in the blank: The prevalence of clinically significant ventricular arrhythmias in dogs is _____ of dogs.
11-16%
What are the potential side effects of Lidocaine when used for treating ventricular arrhythmias?
- Nausea
- Neurological effects (seizure, tremors)
What is the indication for fluid resuscitation in blunt cardiac injury treatment?
To support adequate perfusion
What supraventricular arrhythmias might one see in BCI?
- APCs
- SVTs
–> secondary to atrial contusions
–> less common than ventricular arrhythmias
–> unlikely to be hemodynamically significant
