CTSN Low Cardiac Output and Circulatory Support
Low Cardiac Output & Circulatory Support
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CARDIOGENIC SHOCK
1. Definition
BP systolic < 80 mmHg (or 30 mmHg below basal, BP mean <60 mmHg)
CI < 2 L/min/M
2
(with adequate filling)
LAP and/or RAP > 20 mmHg
Clinical Manifestations of Low C.O.
Decreased peripheral perfusion (pulses, cool, mottled)
Restlessness, confusion decreased mentation
UO < 20-30 ml/hr (adults)
Causes
MI, myocarditis, tamponade, arrhythmias, acute MR/AI
Massive pulmonary embolism, vena caval obstruction, tension pneumothorax
R/O hypovolemia, acidosis, anemia, sepsis
PRIMARY DETERMINANTS OF CARDIOVASCULAR PERFORMANCE
Heart Rate & Rhythm
Sinus Rhythym vs Atrial Fibrillation,AVB; bradycardia; tachycardia
Preload (Ventricular filling)
Frank-Starling effect
Ventricular Compliance (Distensibility)
Effect of ischemia, injury, pericardial space
(Tamponade - decreased CO, BP, Pule Pressure, increased LAP=RAP)
Ventricular Contractility
Inotropes
Sympathomimetic amines, phosphodiesterase inhibitors
Afterload (Vascular resistance)
Vasoactive therapy
SECONDARY DETERMINANTS OF CARDIOVASCULAR PERFORMANCE
Oxygen delivery
O2 carrying capacity (Hgb)
Oxygenation
Metabolic - acid/base status
Acidosis (effect on contractility)
Alkalosis (decreases release of O2 from Hgb, Left shift oxygen-Hgb dissociation curve)
Metabolic stress/load
Fever, agitation, respiratory distress
APPROACH TO CARDIOGENIC SHOCK
Medical Management of Reversible Causes
Primary Determinants of CV Performance
Rate & Rhythm, Preload, Compliance, Contractility, Afterload
Secondary Determinants of CV Performance
Oxygen delivery, Acid/base status, Metabolic load
Assisted Circulation
Intra-Aortic Balloon Pump (IABP)
Cardiopulmonary Support (CPS)
Ventricular Assist Device(s) (VAD's)
Total Artificial Heart (TAH's)
INTRA-AORTIC BALLOON PUMP
1. Indications for Use
Failure to wean from CPB (49%)
Post-MI cardiogenic shock (22%)
Refractory myocardial ischemia (15%)
Post-op cardiogenic shock (7%)
MR or VSD (temporizing)
Ischemic arrhythmias
(Bridge to transplant)
2. Contraindications for Use
Aortic valve insufficiency
Severe peripheral vascular disease (?)
3. Complications
Limb ischemia (5-18%)
Insertion site hemorrhage (2-4%)
Infection (1-2%)
Aortic or iliac perforation (1-2%)
Aortic dissection (1%)
Renal artery embolism or thrombosis (1%)
Mesenteric infarction (1%)
Spinal cord injury (0.5-1%)
Gas embolization/rupture (0.5%)
CVA (0.5%)
4. Results
Post-cardiotomy Failure
75-85% weaned
55% survival
Post-MI Cardiogenic Shock
75% will improve hemodynamically
In post MI use, mortality is 85%
Post-MI + intervention - mortality = 40-50%
ADVANCED MECHANICAL SUPPORT
1. Indications
Post-cardiotomy cardiogenic shock
Post-MI cardiogenic shock
Post-transplant graft failure
High-risk PTCA support
Cardiopulmonary Resuscitation (CPR)
Hypothermia rewarming
Bridge-to-transplant (or recovery)
Alternative to transplantation (future)
POST-CARDIOTOMY MECHANICAL CIRCULATORY SUPPORT
1. Intraoperative Management
Pharmacologic support
Intra-aortic balloon pump
Optimization (volume, metabolic, respiratory, drugs)
Decision for VAD
Patient selection
Early intervention
2. Patient Selection
Inclusion Criteria
Cardiogenic shock: CI <2 l/min/M
2
, BP systolic <80 mmHg
LAP >20 and/or RAP >20 mmHg
(after medical optimization - pre/afterload, respiratory, metabolic)
(after pharmacologic support)
Exclusion Considerations
Technically imperfect operation
Perioperative MI (vs. stunned myocardium)
Age
Preoperative "emergency" status
Massive bleeding
Long CPB
End-organ failure (renal, hepatic, pulmonary .. )
Infection (i.e. endocarditis)
3. Intraoperative Management - Implementation of support
Select VAD, cannulae
Cannulate, implement VAD support
Re-assess cardiac performance
Secure hemostasis
Wound handling (close vs. open)
4. Equipment
Ventricular Assist Devices
(Considerations: cost, availability, familiarity, anticoagulation, blood trauma, monitoring)
Pulsatile, pneumatic
Centrifugal pumps
[ Roller pumps ]
Cannulae
Uptake: R. side: 34-51 Fr; L.side: 28-36 Fr
Return: Ao and PA: 22 Fr
5. Management of VAD Support
Observe for bi-ventricular failure
Institute second VAD as needed
Secure Hemostasis
Reverse Heparin
Fibrin Glue
Wound Handling
Close sternum/skin
Close skin only, support sternum
Leave open (silastic or Esmark ...)
6. Postoperative - General
Maximize Myocardial Recovery
Reduce Inotrope support
Keep heart decompressed
Anticoagulation
Intraop - heparin is reversed
When CT output OK - ACT > 180
When weaning VAD - ACT > 220
Maintain Pulsatile Perfusion (?)
Leave IABP in place
7. Postoperative - Weaning
Time Course
At least 24 hours
But <10% survivorship after 7 days
Follow Recovery
Reduce VAD flow (i.e. to 1L/min)
Observe LAP,RAP,AoP,PAP,SVO2
Observe cardiac function w/ TEE
Remove VAD
With good hemodynamics at low VAD flow
Wean IABP & drips as able
8. Problems
Cardiovascular
RV failure with LVAD
decreased LAP, decreased VAD out, increased RAP
LV failure with RVAD
decreased RAP, decreased VAD out, increased LAP
Hypovolemia (decreased LAP/RAP decreased VAD out)
Cyanosis - shunting through PFO
Device-Related
Thromboemboli
Cannula obstruction
increased LAP/RAP, decreased VAD out
Device failure
Hemolysis
Systemic
Bleeding (30-45% return to OR)
End-organ failure (renal, respiratory, hepatic)
Infection
10. Results
Weaned - 50-60%
Survived - 25-50%
