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

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

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

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

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.

Anatomical Placement

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.

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

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.

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. 12.0 (3/24/04)

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.

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

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

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.

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

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.

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.

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

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

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

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

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)

Battery Charger

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.

Patient Management

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

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

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

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.

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

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

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

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 70-90 mmHg Arterial line waveform dampened

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

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

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

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

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

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: 855-823-8662

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

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

Survival with Primary CF LVAD

Success Stories http://www.omaha.com/article/20111025/NEWS2001/710199974 http://www.youtube.com/watch?v=-zALZGINfAU http://youtu.be/539A2dMOGK8