1. Ventricular Assist Devices
Overview, Patient Management and Emergency Care
Timothy Ryan, APRN-NP

2. Learning Objectives
Identify the components, their function, & theory of device operation of the LVAD
Describe the path blood follows in patients with the LVAD
List two potential complications associated with the LVAD
Identify the purpose and function of the System Controller
Discuss Nursing Care of a Patient with a LVAD
Describe appropriate interventions in the event of an emergency

3. Indication for Use Bridge to Transplant Destination Therapy
Non-reversible left heart failure
Imminent risk of death
Candidate for cardiac transplantation
Destination Therapy
Not candidate for transplant
Lifelong support

4. Considerations Contraindication: Other considerations:
Inability to tolerate anticoagulation
Other considerations:
Nonreversible end organ failure
Acceptance of blood products
Pregnancy
Support system
Compliance history
Youngest patients: pilot study 14 year old, pivotal trial 16 year old
Smallest patient: BSA 1.33

5. HeartMate II Pump
The LVAD is implanted below the diaphragm and attaches to the LV apex and ascending aorta. The velour covered percutaneous lead exits in the right upper quadrant and connects to the system controller which, in this picture, is powered by 2 HM batteries worn in a shoulder holster.

6. Anatomical Placement

7. HeartMate II LVAS System Components
HM II Components:
Implantable titanium blood pump
System Controller
System Components:
System Monitor
Display Module
Power Sources
Power Module
Batteries & Clips
Accessories
Shower Bag
Travel Bag
The HeartMate I and II share many of the same components. Both the system monitor and display module can be upgraded with HM II software eliminating the need to purchase capital equipment.

8. HeartMate II LVAS Valveless Afterload sensitive
Follows native LV pulse
Pump flow varies over the cardiac cycle

9. HeartMate II LVAS Key Design Features
Relatively Simple Design
Valveless
Only one moving part, the rotor
Blood immersed bearings designed for minimization of blood damage
All motor drive and control electronics are outside of the implanted blood pump
Speed range: 6,000 to 15,000 rpm
Flow range: 3 – 10 L/min
The HeartMate II incorporates precision engineering, a simple design, and 30 years of clinical experience.
The rotor spins on precision jeweled ruby bearings. These hydrodynamic bearings are blood immersed, lubricated by the plasma to prevent heat build up that could damage blood with the potential to cause thrombus formation.
There is also the potential for significantly improved durability
The percutaneous lead attaches to the external system controller that controls electronics and motor drive.
Outflow graft with snap on bend relief allows direct visualization during deairing and minimizes risk of kinking
The rotor is capable of providing flow from 3 to 10 liters per minute at a speed range of 6,000 to 15,000 rpm, covering the full cardiac output of a healthy heart.

10. Internal View
The HeartMate II is driven by an electric motor that is integrated into the pump.
Inside the pump’s rotor is a cylindrical magnet. Current is passed through the motor winding, which creates a spinning magnetic field. This spinning magnetic field imparts torque to the rotor and causes the rotor to spin.
Rev (3/24/04)

11. Blood Flow Path Inflow from LV Inlet Stator Rotor Outlet stator
3 vanes “straighten” the flow before it enters the rotor
Rotor
Propel blood toward outflow & spins it radially imparting kinetic energy
Outlet stator
“Straightens” flow as leaves rotor and pressure is further increased
Outflow to ascending aorta
Axial flow pumps, the spinning rotor is in the same linear path as the blood flow.
HM II utilizes a high speed rotor incorporating integral vanes on the surface. These vanes produce the pressure necessary to create flow in a continuous manner.
As blood enters the pump, seen here in slow motion, it is straightened by the inlet stator vanes prior to entering the path of the rotor. The rotor then spins the blood radially and propels it toward the outlet, where blood flow is straightened by the outlet stator vanes.

12. Pump Flow Principles Pump flow is a function of:
The speed of the rotor
↑Speed → ↑Flow
↓Speed → ↓ Flow
The difference in pressure across the pump
↑ Pressure gradient → ↓ Flow
↓ Pressure gradient → ↑ Flow
Rotary pumps have an interdependent relationship between the speed of the rotor, the difference in pressure between the inlet and outlet of the pump (differential pressure) and the amount of flow generated by the device.
The pressure at the inlet of the pump is the left ventricular pressure
The pressure at the outlet of the pump is the aortic pressure
At any given speed, increased B/P will decrease flow

13. Typical Pump Parameters
Speed mean (range) 9,400 rpm (8,000 – 13,000)
Flow mean (range) 5.5 lpm (3.3 – 7.8)

14. Key Points Valveless pump
Retrograde flow will occur if the pump stops
Degree of retrograde flow is determined by pressure differential across the pump
Similar to acute aortic regurgitation
Significant negative pressures can be produced when insufficient blood is provided to the pump
Dehydration or RV failure can cause suction events
Suction events can cause arrhythmias
Retrograde flow will occur if the pump is stopped. The degree is dependent on pressure differential across the pump. For example, during diastole the arterial pressure is approximately 70 mmHg while the ventricular pressure is 20 mmHg resulting in a pressure differential of 50 mmHg. Flow will occur from the aorta to the LV at approximately 1 – 1.5 liters per minute.
Negative pressure can collapse the ventricle and prevent blood from entering the pump. Detection of this occurrence (PI event) will result in automatic reduction in pump speed to low speed limit.
Occurrence of hemolysis should prompt evaluation to rule out pump obstruction and reassess fixed speed setting.

15. System Controller Power Sources System Monitor Display Module
Equipment Overview
System Controller
Power Sources
System Monitor
Display Module

16. System Controller Microprocessor that: Delivers power to the pump
Controls pump speed and power
Monitors, interprets & responds to system performance
Performs diagnostic monitoring
Indicates hazard and advisory alarms
Provides complete backup system
Event recording capability
The system controller has 2 controller boards, one for the primary system operation and one for complete backup system operation in the event the primary system malfunctions or becomes inoperable.
The system controller power leads provide equal power to the pump. The white power lead contains a data link cable that transmits data from the controller to the System Monitor or Display Module when connected to the PBU. To save data &/or waveforms to a card:
White lead - download data to the card
Black lead – save waveform (current trace)
So as long as the cables are intact, transferring the event recorder should be ok with just the white. But for the complete waveform capture data both cables are required.

17. System Controller Perc Lock
Design implemented to prevent accidental percutaneous lead disconnects from the system controller
The perc lock is designed to prevent accidental disconnection of the percutaneous lead from the system controller by covering the metal release tab when in the locked position. It cannot not be turned to the lock position if the percutaneous lead is not fully engaged in the controller socket. It should always be in the locked position once the system controller is attached to the patients’ percutaneous lead.
To lock it, rotate up until the metal tab is completely covered and you hear it click into place. To unlock it, rotate down until the metal tab is exposed and you hear it click into place.

18. HeartMate II Pocket System Controller
Safety by Design
Backup battery
Prioritized visual alarms with clear, actionable instructions
Driveline diagnostic capability
Programmed for use in 37 languages
Designed for an active lifestyle
Lightweight and compact with single-side cable design
Durable, shock-resistant outer case, cables, and electronics
Intuitive, discreet, and comfortable interface
37 language support
240 alarm history (vs. 120 in current controller)
Six most recent alarms are accessible on the controller display
Redundant processors
Boards are connected to the case with “shock mounts” that protect from shock and vibration
Case:
Protects against water and moisture.
Molded magnesium alloy coated for corrosion protection and durability

19. HeartMate II System Controller
Delivers power to the pump
Controls and monitors system operation
Identifies alarm conditions and initiates Hazard and Advisory Alarms
User Interface displays the following available in 37 languages:
Pump parameters (Flow, Speed, Power, PI) and status of Backup Battery charge
Visual alarms with clear, actionable instructions
Accessible alarm history of last six non-transient alarms
Display Module no longer required
Backup battery housed within the controller
Driveline diagnostic capability
Records alarm data and device performance (240 events)
37 language support
240 alarm history (vs. 120 in current controller)
Six most recent hazard alarms are accessible on the User Interface display for communication interpretation and troubleshooting
Redundant processors
Boards are connected to the case with “shock mounts” that protect from shock and vibration
Case:
Protects against water and moisture.
Molded magnesium alloy coated for corrosion protection and durability

20. System Controller User Interface
3 buttons to allow for checking battery status, silencing alarms, display control, and self test and asses last six alarms.
5 LEDs: Low battery, cable connection status, loss of hemodynamic support, compromised controller operations, and controller status

21. Power Module Supplies mains power to LVAD
Serves as the electrical interface between the System Controller and the System Monitor or Display Module
Weights only 10 pounds
Can run off of car power
Provides 30 minutes of backup power
Takes 12 hours to recharge
Keep plugged into grounded outlet at all times
Internal battery must be changed yearly

22. Batteries 14-volt Li-Ion Battery
10+ hours of support on a pair of batteries
Four hours recharge for fully discharged battery
Service life of greater than 2 years (auto recalibration)

23. Battery Charger

24. Display Module Parameters Alarm conditions Pump Mode Pump Speed (rpm)
PI (Pulsatility Index)
Estimated Flow (lpm)
Too low “---”
Too high “+++”
Power (watts)
Alarm conditions
Highest priority alarm message alternates with flow and power
If low estimation is below green zone range, get “---”. If flow estimation is above green zone range, get “+++”.
During alarms, highest priority alarm message alternates with Flow & Power display on lower line.

25. Patient Management

26. Post Op Complications Hypovolemia Right Heart failure
Pulmonary hypertension
Cardiac tamponade
Bleeding
Arrhythmia
Infection
Hemolysis
Thromboembolism
Neurologic dysfunction

27. Potential Late Complications
Hypovolemia
Arrhythmia
Thromboembolism
Infection
Psycho-social issues
Neurological dysfunction

29. Patient Assessment Patient assessment includes: Pump function
Pump speed, flow, motor power, pulse index (PI)
Percutaneous lead connection to system controller and percutaneous lead lock in locked position
Exit site status, immobilization of percutaneous lead
Vital signs, peripheral circulation
Mental status, level of consciousness
Lab work

30. Exit Site Care Dressing change Every Monday and Thursday
Use Sterile Technique
Sterile Gloves and mask
Chlorohexadine Prep
Sterile dressing
Reimbursement lecture to review billing of dressing supplies.

31. Care of the Percutaneous Lead
Damage to the percutaneous lead, depending on the degree, may cause the pump to stop
Do not severely bend, kink or twist the percutaneous lead
Do not “catch” the percutaneous lead in the zipper of the carrying case
Allow for a gentle curve of the percutaneous lead.
Do not severely bend the lead multiple times or wrap it tightly.
Keep the percutaneous lead clean
Wipe off any dirt or grime
If necessary, use a towel with soap and warm water to gently clean the percutaneous lead
Never submerge the lead or other system components in water or liquid

32. Care of the Percutaneous Lead
Do not pull on or move the lead at the exit site
Be mindful of where the system controller is at all times
Protect the controller from falling or pulling on the lead
Don’t allow the percutaneous lead to catch or snag on anything that will pull on or move the lead
Check the percutaneous lead daily for signs of damage
Cuts, holes, tears

33. Warnings & Restrictions
No excessive jumping or contact sports
No swimming
No exposure to MRI
Avoid strong static discharge (i.e. TV, computer screens, vacuuming carpets)
No pregnancy

34. Patient Assessment Vital Signs No pulse No blood pressure
Cannot use automatic blood pressure machine
Doppler used to get mean arterial pressure
Target mean pressure of mmHg
Arterial line waveform dampened

35. Patient Care Arrhythmias Affect pump function
Can be caused by mechanical irritation of ventricular wall by inflow catheter
Must be treated using usual care
ICD’s are turned back on after implant
Cardioversion or defibrillation WILL NOT affect VAD function

36. Patient Care Anticoagulation Because of risk of clot formation in pump
Warfarin with target INR 2.0 to 3.0 (higher if other conditions)
Also on aspirin and dipyridamole therapy

37. Emergency Care Acute Pump Failure Depleted Batteries
Loss of home power and not switched to battery
Controller Failure
Redundant System
Driveline Failure
Pump Failure

38. Emergency Care Acute Pump Failure Causes acute regurgitation to LV
If some LV function, will maintain some blood pressure, but will most likely be in shock
If minimal LV function, regurgitate flow will cause LV to dilate leading to VF
Need to restart pump as soon as possible
10 minute rule

39. Emergency Care Cardiopulmonary Resuscitation
May perform cardioversion or defibrillation as needed. Will not affect VAD or controller
No CPR
Unless last resort
May dislodge inflow or outflow cannulas resulting in hemorrhage
Treat like cardiogenic shock if pump failure

40. Emergency Care Routing of Patients
Most patients will need to be transferred to The Nebraska Medical Center.
May first present to local ED for stabilization then transferred to The Nebraska Medical Center, if needed.
Other centers will not be able to treat pump related issues
Toll-Free Emergency Contact:

41. Exercising And Cardiac Rehabilitation
Need to have doppler to evaluate blood pressure
No limitations to equipment used
Limit exercise to no higher than Borg level of 13
Initially may have higher means
Will decrease over time
Strongly encourage Phase III

42. The Nebraska Medical Center MCS Program
Top 15% of Implanting Centers in the United States

43. Survival with Primary CF LVAD

45. Success Stories