Successful resuscitation after prolonged cardiac arrest in a patient with massive hypertrophic cardiomyopathy
Tzevan Poon, MD; Marshall Corson, MD; Stephen Hubbard, MD
Department of Medicine (TP, MC, SH), Division of Cardiology (MC, SH), Harborview Medical Center, University of Washington. Seattle, WA 98104
Background: Sudden cardiac death (SCD)is a feared event in patients with hypertrophic cardiomyopathy (HCM), and most commonly afflicts those younger than 35 years old[1].The risk of SCD has an estimated incidence of 1-2% per year. Risk factors for cardiac arrest in patients with HCM include a family history of SCD, otherwise unexplained syncope, non-sustained ventricular tachycardia (NSVT), abnormal cardiopulmonaryexercise testing, and massive left ventricular hypertrophy (LVH)defined as left ventricular (LV) wall thickness 30mm (normal wall thickness <15mm) [1,2]. Resuscitation of HCM patients in cardiac arrest may pose numerous challengesdue tothe presence of severe LVH, dynamic LV outflow tract obstruction, mitral regurgitation, and diastolic dysfunction[1].
Objective: To report successful resuscitation with full neurologic recovery of a patient with massive HCM after cardiac arrest despitenearly two hoursbefore return of sustained spontaneous circulation; and to underscore the importance of aggressive resuscitation and smooth transitions of care throughout thechain of survival despite unique logistical and medical challenges.
Methods and Findings: A 19 year old previously asymptomatic male, diagnosed since age 13 with autosomal dominant HCM, waswith two friends in a foresttalking pictures of elk about 100 feet from the road at a remote national park,when he suffered cardiac arrest at approximately 1605.Out of cellular phone range, one friend ran to flag down a car, while the other started CPR and rescue breathing. Both friends learned basic life support (BLS) in public school. US park rangers arrived at about 1625and took over chest compressions. Firefighters arrived9 minutes later with an automated external defibrillator. The patient wascardioverted twice and a weak but palpable pulse with a blood pressure of 80mmHg/palpation was achieved at 1648, 43 minutes after CPR was first started. The patient was transported by rigid backboard off the trail and was sent by ambulance to a local airstrip. However the patient’s heart rhythm soon degraded into pulseless ventricular tachycardia and CPR was resumed.
Critical care airliftwas dispatched by helicopter at 1631 and arrived at 1702. Airlift nurses found the patientcold, cyanotic, with a Glasgow Coma Score of 3, and covered in vomit. Blood glucose was 115mg/dL. They intubated the patient with a 7.5 endotracheal tubeusing a Glidescope video laryngoscope(Verathon, Inc. Bothell, WA). CPR was continued for another 55 minutes, from 1707 to 1802,for ventricular fibrillation, ventricular tachycardia, and pulseless electrical activity. He was cardioverted an additional 6 times during this time. During the resuscitation, the patient was given intravenous boluses of epinephrine 1mg on four occasions, vasopressin 40 units once, calcium chloride 10mg/kg once, sodium bicarbonate 50mEq twice, atropine 2mg once, lidocaine 100mg twice,amiodarone 300mg once, andmagnesium 2gm once. He received 1.2 liters of crystalloid. End tidal carbon dioxide monitoring used during CPR averaged only 17mmHg.
Thepatient was airlifted at 1810, and arrived at our Emergency Department (ED)at 1842. His temperature was 35.2C, heart rate was 67 beats per minute, andblood pressure 78/40mmHg. A bolus of 100micrograms of epinephrine was given. We then used a portableultrasound (M-Turbo, Sonosite. Bothell, WA) to obtain a 4 chamber view of the heart which showed severe LVH and complete obliteration of the intraventricular chamber during systole suggesting that the patient was quite hypovolemic. We bolused 3 liters of crystalloid and the patient becamehemodynamically stable without further need for inotropes or vasopressors. He was started on an amiodarone drip. We cooled the patient in the EDusing an external temperature management system (Artic Sun. Medivance, Inc. Louisville, Colorado) in accordance with our institution’s mild hypothermia protocol; and hequickly reached a goal temperature of32.4C,123 minutes after arrival.
Computer tomography of the head and neck showed no acute intracranial or cervical abnormality. Urine toxicology was negative for illicit substances. We treated the patient for non-ST elevation myocardial infarction (troponin-I peaked at 38.2ng/mL), pneumothorax and pneumomediastinum due to CPR, aspiration pneumonia, shock liver, acute kidney injury, and rhabdomyolysis.
The patient was rewarmed after 24 hours to 37.4C(though his temperature rose spontaneously to 38.7C for a brief period). A formal transthoracic echocardiogram (TTE) obtained on hospital day 1showed severe asymmetric hypertrophy with the intraventricular septum measuredat 42mm from the subcostal view. The LV lateral wall was 31mm.A follow-up studyshowedsevere LV outflow obstruction with a calculated peak gradient of 67mmHg (Figure 1, panel A). Right and left ventricular systolic function was normal.
The patient continued to have no evidence of higher cortical function until hospital day 3 when he began to respond to simple commands. He was extubated on day 4 with no focal neurological deficits. By day 6 he was speaking fluently, chatting with his friends, and using the Internet on his smartphone. An episode of 12 seconds of rapid monomorphic NSVT (300 beats per minute) was noted on hospital day 6 (Figure 1, panel B). Formal neurocognitive testing initially showed isolated moderate memory deficits; however heimprovedand had onlymild memory deficits on repeat testing prior to discharge.
An automated implantable cardioverter defibrillator (AICD - Secura DR.Medtronic, Inc. Minneapolis, MN) was inserted on day 15. The patient was discharged home on day 17.Routine AICD interrogation shows that he continues to have brief episodes of asymptomatic NSVT. He has not received any AICD discharges. Eight months later our patientreports onlytrace occasional short-term memory loss. Hehas an active social life, and works at a local retail sports shop.
Discussion: To our knowledge, this is the longest documented resuscitation of a patient with HCM with good outcome. We calculate his two episodes of total pulselessness lasted 43 and 55 minutes, and 117 minutes before return of sustained spontaneous circulation.
We attribute the recovery of this patient to an uninterrupted chain of survival – includinggoodqualityCPR with frequent rotations;early cardioversion by first responders; transition to ACLS when available;expeditious transport to a tertiary care facilitythat cares for a high-volume of cardiac arrest patients; and early use of therapeutic mild hypothermia [3]. The patient’s youth and his prior high level of fitness may have alsohelped him survive.
This patient was quite cool on arrival from the field and was subsequently further cooled. Mild hypothermia (32 - 35C) has beenshown to improvedneurological protection after cardiac arrest [4]. A randomized pilot study of 125 patients suggested that prehospital induction of mild hypothermia after return of spontaneous circulation from cardiac arrest may improve neurological outcome [5]. A larger multi-center randomized trial evaluating this timed intervention is ongoingat our institution.
This case report also illustrates the benefitof point-of-care ultrasoundin directing resuscitation efforts. We recommend ongoingcollaborations with Cardiology, Emergency Medicine, and Critical Care departments to safelydevelop and deploy this emerging diagnostic modality.
In summary, we demonstrate that successful outcome may be possible in patients with HCMdespite challenging logistical issues, massivehypertrophic cardiomyopathy, and very prolonged resuscitation.
(We thank the first responders, US National Parks Service rangers, firefighters of the cities of Greenwater and Buckley, and theUniversity of Washington Airlift Northwest crew for being instrumental in this rescue.)
Potential Conflicts of Interest: None reported.
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