Posted by American Heart Association, Inc. on Nov 20th 2019
2019 AHA Focused Updates Released November 14, 2019 Part 5 Adult Basic Life Support (BLS) and Cardiopulmonary Resuscitation (CPR) Quality - Continued
Immediate Recognition and Activation of the Emergency Response System – Dispatcher-Assisted CPR
We recommend that emergency dispatchers determine if a person is unresponsive with abnormal breathing after acquiring the requisite information to determine the location of the event.
If the person is unresponsive with abnormal or absent breathing, it is reasonable for the emergency dispatcher to assume that the patient is in cardiac arrest.
Dispatchers should be educated to identify unresponsiveness with abnormal breathing and agonal gasps across a range of clinical presentations and descriptions.
We recommend that emergency dispatch centers offer CPR instructions and empower
dispatchers to provide such instructions for adult patients in cardiac arrest.
Dispatchers should instruct callers to initiate CPR for adults with suspected out-of-hospital cardiac arrest.
We recommend that when dispatchers’ instructions are needed, dispatchers should provide chest compression–only CPR instructions to callers for adults with suspected out-of-hospital cardiac arrest.
The EMS system quality improvement process, including review of the quality of dispatcher CPR instructions provided to specific callers, is considered an important component of a high-quality lifesaving program.
Note: Further information regarding Dispatch-Assisted CPR can be found in
The healthcare provider should take no more than 10 seconds to check for a pulse and, if the rescuer does not definitely feel a pulse within that time period, the rescuer should start CPR beginning with chest compressions.
Ideally, the healthcare provider performs a pulse check at the same time as the check for no breathing or only gasping, to minimize delay in detection of cardiac arrest and initiation of CPR.
Lay rescuers should not interrupt chest compressions to palpate pulses or check for ROSC.
Begin chest compressions as quickly as possible after recognition of cardiac arrest.
It may be reasonable for rescuers to initiate CPR with chest compressions.
Early Defibrillation With an Automated External Defibrillator
Single rescuer:
After activating the emergency response system, retrieve an AED (if nearby and easily accessible) and then return to the victim to attach and use the Automated External Defibrillator (AED) and provide CPR.
Two or more trained rescuers:
- One rescuer begins CPR, starting with chest compressions.
- Second rescuer activates the emergency response system and gets the AED (or a manual defibrillator in most hospitals) and other emergency equipment.
- Use the AED or manual defibrillator as rapidly as possible.
- Both rescuers provide CPR with chest compressions and ventilation.
See, also, Defibrillation with an AED, below.
Rescuer-Specific CPR Strategies: Putting It All Together
The specific steps for rescuers and healthcare providers (compression-only [Hands-Only™] CPR, conventional CPR with rescue breaths, and CPR with AED use) are determined by the rescuer’s level of training.
Untrained Lay Rescuer
Untrained lay rescuers should provide compression-only CPR, with or without dispatcher assistance.
The rescuer should continue compression-only CPR until the arrival of an AED or rescuers with additional training.
Lay Rescuer Trained in Chest Compression-Only CPR
For lay rescuers trained in chest compression–only CPR, we recommend they provide chest compression–only CPR for adults in out-of-hospital cardiac arrest.
For lay rescuers trained in CPR using chest compressions and ventilation (rescue breaths), it is reasonable to provide ventilation (rescue breaths) in addition to chest compressions for the adult in out-of-hospital cardiac arrest.
The rescuer should continue compression-only CPR until the arrival of an AED or rescuers with additional training.
Lay Rescuer Trained in CPR Using Chest Compression and Ventilation
All lay rescuers should, at a minimum, provide chest compressions for victims of cardiac arrest.
For lay rescuers trained in CPR using chest compressions and ventilation (rescue breaths), it is reasonable to provide ventilation (rescue breaths) in addition to chest compressions for the adult in out-of-hospital cardiac arrest.
The rescuer should add rescue breaths in a ratio of 30 compressions to 2 breaths. The rescuer should continue CPR until an AED arrives and is ready for use or EMS providers take over care of the victim.
All healthcare providers should be trained in BLS.
It is realistic for healthcare providers to tailor the sequence of rescue actions to the most likely cause of arrest.
For example, if a lone healthcare provider sees an adolescent suddenly collapse, the provider may assume that the victim has had a sudden arrhythmic arrest and call for help, get a nearby AED, return to the victim to use the AED, and provide CPR.
It is reasonable for healthcare providers to provide chest compressions and ventilation for all adult patients in cardiac arrest, from either a cardiac or noncardiac cause.
If a lone healthcare provider aids an adult drowning victim or a victim of foreign body airway obstruction who becomes unconscious, the healthcare provider may give about 5 cycles (approximately 2 minutes) of CPR before activating the emergency response system.
Verify Scene Safety
Rescuers arriving on the scene of an emergency should verify that the environment in which they are approaching a patient is safe for the provider.
Because of the difficulty in providing effective chest compressions while moving the person during CPR, the resuscitation should generally be conducted where the patient is found. (Class IIa, LOE C) (2010 Part 5)
If the environment is dangerous, it may be necessary to move the victim.
The first step in the treatment of cardiac arrest is recognition.
When a bystander witnesses the sudden collapse of a victim or finds someone who appears lifeless, the bystander should:
- Ensure the scene is safe
- Check for responsiveness (tap shoulder and shout, “Are you all right?”)
- If victim doesn’t respond, activate emergency response system
When phoning 911, the bystander should be prepared to provide:
- location of the incident,
- the events of the incident,
- the number and condition of the victim(s),
- the type of aid provided.
The bystander should:
- be prepared to follow the dispatcher’s instructions.
- hang up only when instructed to do so by the dispatcher.
After activation of the emergency response system, the rescuer immediately begins CPR for adult victims who are unresponsive with no breathing or no normal breathing (only gasping).
Dispatchers should instruct rescuers to provide CPR if the victim is unresponsive with no normal breathing, even when the victim demonstrates occasional gasps.
The rescuer should treat the victim who has occasional gasps as if he or she is not breathing.
If a lone rescuer finds an unresponsive adult (ie, no movement or response to stimulation) or witnesses an adult who suddenly collapses, after ensuring the scene is safe, the rescuer should check for a response by tapping the victim on the shoulder and shouting at the victim. The trained or untrained bystander should—at a minimum—activate the community emergency response system…If the victim also has absent or abnormal breathing (ie, only gasping), the rescuer should assume the victim is in cardiac arrest.
The health care provider should also check for no breathing or no normal breathing (eg. only gasping) while checking for responsiveness; if the healthcare provider finds the victim is unresponsive with no breathing or no normal breathing (ie, only gasping), the rescuer should assume the victim is in cardiac arrest and immediately activate the emergency response system.
Because delays in chest compressions should be minimized, the healthcare provider should take no more than 10 seconds to check for a pulse; and if the rescuer does not definitely feel a pulse within that time period the rescuer should start chest compressions.
Scenario: Pulse Present, Normal Breathing
Closely monitor the patient, and activate the emergency response system as indicated by location and patient condition.
Scenario: Pulse Present, No Normal Breathing
For a patient with known or suspected opioid overdose who has a definite pulse but no normal breathing or only gasping (ie, a respiratory arrest), in addition to providing standard BLS care, it is reasonable for appropriately trained BLS healthcare providers to administer intramuscular or intranasal naloxone.
For patients in cardiac arrest, medication administration is ineffective without concomitant chest compressions for drug delivery to the tissues, so naloxone administration may be considered after initiation of CPR if there is high suspicion for opiate overdose.
It is reasonable to provide opioid overdose response education with or without naloxone distribution to persons at risk for opioid overdose (or those living with or in frequent contact with such persons).
See Ventilation with Bag-Mask Device Before Placement of an Advanced Airway, below.
Chest compressions are
- forceful rhythmic applications of pressure over the lower half of the sternum.
Characteristics of effective chest compressions:
- adequate depth (2-2.4 inches or 5-6 cm)
- adequate rate (100-120/min)
- complete recoil after each compression
- minimal number and duration of interruptions in chest compressions
Effective chest compressions are essential for providing blood flow during CPR. For this reason all patients in cardiac arrest should receive chest compressions.
Hand Position During Compressions
It is reasonable to position hands for chest compressions on the lower half of the sternum in adults with cardiac arrest.
The rescuer should place the heel of one hand on the center (middle) of the victim’s chest (which is the lower half of the sternum) and the heel of the other hand on top of the first so that the hands are overlapped and parallel.
Compression rate is defined as the actual rate (compressions per minute) used during each continuous period of chest compressions.
In adult victims of cardiac arrest, it is reasonable for rescuers to perform chest compressions at a rate of 100/min to 120/min.
The depth of chest compressions can affect the relative increase in intrathoracic pressure and, in turn, influence forward blood flow from the heart and great vessels to and through the systemic and pulmonary circulations.
During manual CPR, rescuers should perform chest compressions to a depth of at least 2 inches or 5 cm for an average adult, while avoiding excessive chest compression depths (greater than 2.4 inches or 6 cm).
Chest compressions should be performed with chest compression and chest recoil/relaxation times approximately equal.
Full chest wall recoil occurs when the sternum returns to its natural or neutral position during the decompression phase of compressions. When the chest recoils, the heart fills with blood. If rescuers “lean” on the chest between compressions and do not allow complete chest recoil, blood return to the heart is reduced and the heart does not fill with as much blood. This reduces the output of the next compression.
It is reasonable for rescuers to avoid leaning on the chest between compressions to allow full chest wall recoil for adults in cardiac arrest.
Minimizing Interruptions in Chest Compressions
Interruptions in chest compressions, whether intended (eg. for required care such as rhythm analysis) or unintended, will stop blood flow.
Expert consensus is that a goal of 80% chest compression fraction (proportion of resuscitation time that chest compressions are performed) is achievable if the team trains well and works together.This requires minimizing both the number and duration of interruptions in chest compressions. The Guidelines recommendations (see below) note that the chest compression fraction should be at least 60%, but CPR Quality experts note that a goal of 80% is very achievable.
Interruptions in chest compressions for attempted defibrillation requires team coordination and practice to minimize the pause between the last compression and shock delivery, and to ensure that compressions are resumed immediately after shock delivery.
Shorter interruptions for shock delivery are associated with greater likelihood of shock success, greater likelihood of return of spontaneous circulation, and greater survival to hospital discharge.
In adult cardiac arrest, total preshock and postshock pauses in chest compressions should be as short as possible.
For adults in cardiac arrest receiving CPR without an advanced airway, it is reasonable to pause compressions for less than 10 seconds to deliver 2 breaths.
In adult cardiac arrest without an advanced airway, it may be reasonable to perform CPR with the goal of a chest compression fraction (ie, the proportion of time that compressions are performed) as high as possible, with a target of at least 60%.
When 2 or more rescuers are available it is reasonable to switch chest compressors approximately every 2 minutes (or after about 5 cycles of compressions and ventilation at a ratio of 30:2) to prevent decreases in the quality of compressions. (Class IIa, LOE B) (2010 Part 5)
Consider switching compressors during interventions associated with appropriate interruptions in chest compressions (eg. when an AED is delivering a shock).
Every effort should be made to switch compressors in <5 seconds.
If the 2 rescuers are present, they can be positioned on either side of the patient, so 1 rescuer will be ready and waiting to relieve the “working compressor” every 2 minutes.
Compression-to-Ventilation Ratio
It is reasonable for rescuers trained in CPR using chest compressions and ventilation (rescue breaths) to provide a compression-to-ventilation ratio of 30:2 for adults in cardiac arrest.
The rescuer delivers breaths during pauses in compressions and delivers each breath over approximately 1 second.
It is reasonable that before placement of an advanced airway (supraglottic airway or tracheal tube), EMS providers perform CPR with cycles of 30 compressions and 2 breaths. It may be reasonable for EMS providers to use a rate of 10 breaths per minute (1 breath every 6 seconds) to provide asynchronous ventilation during continuous chest compressions before placement of an advanced airway.
For victims with suspected spinal injury, rescuers should initially use manual spinal motion restriction (eg. placing 1 hand on either side of the patient’s head to hold it still) rather than immobilization devices, because use of immobilization devices by lay rescuers may be harmful.
The trained lay rescuer who feels confident that he or she can perform both compressions and ventilation should open the airway using a head tilt–chin lift maneuver.
Open the Airway: Healthcare Provider
Although the head tilt–chin lift technique was developed using unconscious, paralyzed adult volunteers and has not been studied in victims with cardiac arrest, clinical and radiographic evidence and a case series have shown it to be effective.
If healthcare providers suspect a cervical spine injury, they should open the airway using a jaw thrust without head extension.
Because maintaining a patent airway and providing adequate ventilation are priorities in CPR use the head tilt–chin lift maneuver if the jaw thrust does not adequately open the airway.
Rescue Breaths and Rescue Breathing
During CPR, cardiac output is about 25% to 33% of normal, so oxygen uptake from the lungs and CO2 delivery to the lungs are also reduced. As a result, a low minute ventilation (tidal volume lower than normal and respiratory rate slower than normal) can maintain effective oxygenation and ventilation.
Excessive ventilation is not necessary and can be harmful because it increases intrathoracic pressure, decreases venous return to the heart, and decreases cardiac output and survival. It can also cause gastric inflation and resultant complications such as regurgitation and aspiration.
Deliver each rescue breath over 1 second.
Give a sufficient tidal volume to produce visible chest rise.
During adult CPR tidal volumes of approximately 500 to 600 mL (6 to 7 mL/kg) should suffice. This is consistent with a tidal volume that produces visible chest rise.
Rescuers should avoid excessive ventilation (too many breaths or too large a volume) during CPR.
If an adult victim with spontaneous circulation (eg. strong and easily palpable pulses) requires support of ventilation, the healthcare provider should give rescue breaths at a rate of about 1 breath every 5 to 6 seconds, or about 10 to 12 breaths per minute. Note: When a perfusing rhythm is present, pulmonary blood flow and carbon dioxide delivery to the lungs may be normal or near-normal, so a slightly higher ventilation rate will likely be required to match ventilation to perfusion. See Ventilation During CPR with an Advanced Airway.
Mouth-to-Mouth Rescue Breathing
Mouth-to-mouth rescue breathing provides oxygen and ventilation to the victim.
Give 1 breath over 1 second, take a “regular” (not a deep) breath, and give a second rescue breath over 1 second.
Mouth-to-Nose and Mouth-to-Stoma Ventilation
Mouth-to-nose ventilation is recommended if ventilation through the victim’s mouth is impossible (eg, the mouth is seriously injured), the mouth cannot be opened, the victim is in water, or a mouth-to-mouth seal is difficult to achieve.
Give mouth-to-stoma rescue breaths to a victim with a tracheal stoma who requires rescue breathing. A reasonable alternative is to create a tight seal over the stoma with a round, pediatric face mask.
Ventilation with Bag-Mask Device Before Placement of an Advanced Airway
The elements of a bag-mask device include:
- non-jam inlet valve
- either no pressure relief valve or a pressure relief valve that can be bypassed
- standard 15-mm/22-mm fittings
- an oxygen reservoir to allow delivery of high oxygen concentrations
- a nonrebreathing outlet valve that cannot be obstructed by foreign material and will not jam with an oxygen flow of 30 L/min
- the capability to function satisfactorily under common environmental conditions and extremes of temperature.
Masks should be:
- made of transparent material to allow detection of regurgitation.
- capable of creating a tight seal on the face, covering both mouth and nose.
- fitted with an oxygen (insufflation) inlet and have a standard 15-mm/22-mm connector.
- available in one adult and several pediatric sizes.
It is reasonable for rescuers to use an adult (1 to 2 L) bag to deliver approximately 600 mL tidal volume for adult victims. This amount is usually sufficient to produce visible chest rise and maintain oxygenation and normocarbia in apneic patients.
It is reasonable that before placement of an advanced airway (supraglottic airway or tracheal tube), EMS providers perform CPR with cycles of 30 compressions and 2 breaths.
It may reasonable for EMS providers to use a rate of 10 breaths per min (1 breath every 6 seconds) to provide asynchronous ventilation during continuous chest compressions before placement of an advanced airway.
Ventilation with an Advanced Airway during CPR
Either bag-mask-ventilation or an advanced airway strategy
may be considered during CPR for adult cardiac arrest in any setting. (2019
ACLS)
For further information about choice of advanced airway strategy, see Advanced
Cardiovascular Life Support Section (Part 7).
If an advanced airway is used, the supraglottic airway
can be used for adults with OHCA in settings with low tracheal intubation
success rate or minimal training opportunities for endotracheal tube placement.
(2019
ACLS)
If an advanced airway is used, either the supraglottic airway or endotracheal tube can be used for adults with OHCA in settings with high tracheal intubation success rates or optimal training opportunities for endotracheal tube placement. (2019 ACLS)
Frequent experience or frequent retraining is recommended for providers who perform endotracheal intubation.
Emergency medical services systems that perform prehospital intubation should provide a program of ongoing quality improvement to minimize complications and to track overall supraglottic airway and endotracheal tube placement success rates.
When the victim has an advanced airway in place during CPR, rescuers no longer deliver cycles of 30 compressions and 2 breaths (ie, they no longer interrupt compressions to deliver 2 breaths). Instead, it may be reasonable for the provider to deliver 1 breath every 6 seconds (10 breaths per minute) while continuous chest compression are being performed.
Whenever an advanced airway (endotracheal tube or supraglottic device) is inserted during CPR, it may be reasonable for providers to perform continuous compressions with positive-pressure ventilation delivered without pausing chest compressions.
It may be reasonable for the provider to deliver 1 breath every 6 seconds (10 breaths per minute) while continuous chest compressions are being performed.
Passive Oxygen Versus Positive-Pressure Oxygen During CPR
We do not recommend the routine use of passive ventilation techniques during conventional CPR for adults.
For witnessed OHCA with a shockable rhythm, it may be reasonable for EMS systems with priority-based, multitiered response to delay positive-pressure ventilation by using a strategy of up to 3 cycles of 200 continuous compressions with passive oxygen insufflation and airway adjuncts.
A reasonable alternative for EMS systems that have adopted bundles of care is the initial use of minimally interrupted chest compressions (ie, delayed ventilation) for witnessed shockable OHCA.
Cricoid pressure — pros:
- can prevent gastric inflation and reduce the risk of regurgitation and aspiration during bag-mask ventilation
Cricoid pressure — cons:
- may impede ventilation during bag-mask ventilation
- can delay or prevent the placement of an advanced airway
- aspiration can occur during placement of an advanced airway despite use of cricoid pressure.
- training in the application of cricoid pressure is difficult
- in studies, both expert and non-expert rescuers fail to demonstrate mastery of the technique
- in studies, applied pressure was frequently inconsistent and outside of effective limits.
Cricoid pressure might be used in a few special circumstances (eg. to aid in viewing the vocal cords during tracheal intubation). However, the routine use of cricoid pressure in adult cardiac arrest is not recommended.
Rapid defibrillation is the treatment of choice for ventricular fibrillation of short duration, such as for victims of witnessed out-of-hospital cardiac arrest or for hospitalized patients whose heart rhythm is monitored.
For witnessed adult cardiac arrest when an AED is immediately available, it is reasonable that the defibrillator be used as soon as possible.
For adults with unmonitored cardiac arrest or for whom an AED is not immediately available, it is reasonable that CPR be initiated while the defibrillator equipment is being retrieved and applied and that defibrillation, if indicated, be attempted as soon as the device is ready for use.
After activating the emergency response system the lone rescuer should next retrieve an AED (if nearby and easilt accessible) and then return to the victim to attach and use the AED. The rescuer should then provide high-quality CPR. When 2 or more rescuers are present, one rescuer should begin chest compressions while a second rescuer activates the emergency response system and gets the AED (or a manual defibrillator in most hospitals).
Analysis of Rhythm During Compressions
There is insufficient evidence to recommend the use of artifact-filtering algorithms for analysis of ECG rhythm during CPR. Their use may be considered as part of a research protocol or if an EMS system, hospital, or other entity has already incorporated ECG artifact-filtering algorithms in its resuscitation protocols.
Pausing to assess the rhythm after shock delivery increases the time that chest compressions are interrupted.
Compressions are needed immediately after shock delivery to provide blood flow and coronary perfusion: Even if a shock eliminates VF, it takes time for the heart to resume a perfusing rhythm.
Shorter “perishock pauses” (ie, total time compressions are interrupted for shock delivery) are associated with greater likelihood of shock success, greater likelihood of return of spontaneous circulation, and greater survival to hospital discharge.
For these reasons, immediate resumption of chest compressions, with a rhythm check after about 2 minutes of CPR, is preferred.
It may be reasonable to immediately resume chest compressions after shock delivery for adults in cardiac arrest in any setting.
CPR Quality, Accountability, and Healthcare Systems
It may be reasonable to use audiovisual feedback devices during CPR for real-time optimization of CPR performance.
Resuscitation from cardiac arrest most often involves a team of caregivers with varied experience and composition.
A designated team leader directs team activities with the aim to minimize interruptions in CPR, ensure delivery of adequate compression rate and depth, minimization of leaning and avoidance of excessive ventilation.
We have not yet determined an optimal duration of resuscitation before the termination of efforts nor identified which patients may benefit from prolonged efforts at resuscitation. However, limited evidence suggests that extending the duration of resuscitation may be a means of improving survival in selected hospitalized patients.
Observational data from registries can be a valuable resource for studying and reporting resuscitation processes and outcomes.
The AHA’s Get-With-The-Guidelines-Resuscitation registry is the largest prospective, multicenter, observational registry of in-hospital cardiac arrest.
The Resuscitation Outcomes Consortium (ROC) is a clinical research network that evaluated the effectiveness of prehospital emergency care for patients with OHCA or life-threatening injury.
The Cardiac Arrest Registry to Enhance Survival (CARES) is a central US repository of data from OHCA events of presumed cardiac etiology treated with CPR and/or defibrillation.
Family Presence During Resuscitation
With some evidence for improved psychological benefits for families present during out-of-hospital resuscitation and without an apparent negative effect on outcomes at hospitals that allow families to be present, family presence represents an important dimension in the paradigm of resuscitation quality.
There are several variations of the recovery position. The position used should be stable, near a true lateral position, with the head dependent and with no pressure on the chest to impair breathing.
Special Resuscitation Situations
Note: This topic was last reviewed in 2010. Refer to the current American College of Cardiology/AHA published clinical practice guidelines for full details on the management of ACS, including recommendations for treatment of ST-Elevation Myocardial Infarction and treatment for Unstable Angina/Non-ST-elevation Myocardial Infarction. (2014 NSTEMI Guidelines) (2015 Update PCI STEMI) (2013 STEMI Guideline)
Note: These recommendations were last reviewed in 2019. Refer to 2018 Guidelines for the Early Management of Patients With Acute Ischemic Stroke and 2019 Stroke Update for complete current recommendations.
Refer to the most recent ILCOR statement regarding drowning.
Refer to Cardiac Arrest in Special Situations, Part 10.
Foreign-Body Airway Obstruction (Choking)
Although chest thrusts, back slaps, and abdominal thrusts are feasible and effective for relieving severe foreign body airway obstruction in conscious (responsive) adults and children >1 year of age, for simplicity in training it is recommended that abdominal thrusts be applied in rapid sequence until the obstruction is relieved.
If abdominal thrusts are not effective, the rescuer may consider chest thrusts.
Monica E. Kleinman, MD, Chair; Zachary D. Goldberger, MD, MSc, FAHA; Thomas Rea, MD, MPH; Robert A. Swor, DO; Bentley J. Bobrow, MD, FAHA; Erin E. Brennan, MD, MMEd; Mark Terry, MPA, NRP; Robin Hemphill, MD, MPH; Raúl J. Gazmuri, MD, PhD; Mary Fran Hazinski, MSN, RN, FAHA; Andrew H. Travers, MD, MSc
Lorrel E. Brown; Tomas Drabek; Judith Finn; Fredrik Folke; Guillaume Geri; James T. Niemann
Table 3: Part 5: BLS and CPR Quality: 2017 Guidelines Update Reviewer Disclosures
Monica E. Kleinman, Chair; Erin E. Brennan; Zachary D. Goldberger; Robert A. Swor; Mark Terry; Bentley J. Bobrow; Raúl J. Gazmuri; Andrew H. Travers; Thomas Rea
Table 4: Part 5: Adult Basic Life Support and Cardiopulmonary Resuscitation Quality: 2015 Guidelines Update Writing Group Disclosures
Robert A. Berg, Chair; Robin Hemphill; Benjamin S. Abella; Tom P. Aufderheide; Diana M. Cave; Mary Fran Hazinski; E. Brooke Lerner; Thomas D. Rea; Michael R. Sayre; Robert A. Swor
The American Heart Association requests that this document be cited as follows:
American Heart Association. Web-based Integrated Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care – Part 5: Adult Basic Life Support and Cardiopulmonary Resuscitation Quality. ECCguidelines.heart.org.
© Copyright 2015, 2017 American Heart Association, Inc.