Role of thrombolytic agents in cardiac arrest

Cardiac Thrombus Formation During Cardiopulmonary Resuscitation for Cardiac Arrest: Is It Time for Ultrasound-Enhanced Algorithms?

Current guidelines consider thrombosis as a potential (and reversible) cause of cardiorespiratory arrest (CA). However, cardiac thrombus formation (TF) is likely to be the consequence of the forward blood flow ceasing during cardiac standstill. We present the case of a young man who was hospitalized for infective endocarditis, complicated by multiorgan disease and sudden CA on the 5^th day. Prompt cardiopulmonary resuscitation (CPR) warranted a return of spontaneous circulation in 16 min but, unexpectedly, a TF was recognized in the right atrium at echocardiography. The blood clot resolved with rapid administration of endovenous heparin and continued chest compressions. Even though cardiac ultrasound is not ready for a routine use during CPR, the present study confirms a key role in the management of CA patients.

Cardiac arrest due to pulmonary embolism

Pulmonary embolism (PE) is a potentially life threatening clinical condition that is fairly non-specific in presentation. Massive pulmonary embolism (PE) without cardiac arrest has been associated with a mortality rate of 30%. However, when cardiac arrest ensues, mortality may be as high as 95%. Since outcomes of cardiac arrest following PE are generally dismal, any available potentially life-saving measure must be instituted when the diagnosis of PE is suspected. Despite a lack of randomized controlled trials guiding the management of suspected PE in the cardiac arrest victim, thrombolysis and other therapies have been associated with good outcomes in the handful of published case reports and other small studies.

Thrombolysis during Extended Cardiopulmonary Resuscitation for Autoimmune-Related Pulmonary Embolism

Massive pulmonary embolism (MPE) is one of the potentially reversible causes of cardiac arrest and pulseless electrical activity. At present, a fear of lethal haemorrhage makes thrombolytic therapy prohibitive during cardiopulmonary resuscitation. Blood hypercoagulability in autoimmune disorders (such as autoimmune haemolytic anaemia) carries a risk of MPE. Prompt diagnosis is critical for timely thrombolytic intervention. We reported a 23-year-old female with 10 years medical history of autoimmune haemolytic anaemia developed cardiac arrest in our emergency intensive care unit. Electrocardiogram and echocardiogram findings indicated the possibility of MPE, so fibrinolytic therapy with alteplase was administered along with prolonged cardiopulmonary resuscitation. Her neurological recovery was generally good, and no major bleeding occurred. MPE was confirmed by computed tomography pulmonary angiography afterwards. We regard that once there is presumptive diagnosis of MPE, initiating early thrombolysis during cardiopulmonary resuscitation may be considered. (Hong Kong j.emerg.med. 2016;23:180-185)

Association of antiplatelet therapy with patient outcomes after out-of-hospital cardiac arrest

BACKGROUND

Cessation of blood flow during out-of-hospital cardiac arrest (OHCA) results in microvascular thrombosis, protracted hypoperfusion after return of spontaneous circulation and damage to vital organs. We tested the hypothesis that pre-arrest antiplatelet and anticoagulant medication use would be associated with less post-arrest organ dysfunction and better outcomes.

METHODS

We included OHCA patients treated from January 2005 to October 2014 at a single academic medical center. We combined our prospective OHCA registry of clinical and demographic data with a structured chart review to abstract home antiplatelet and anticoagulant medications. We fit unadjusted and adjusted regression models to test the association of antiplatelet and anticoagulant medication use with early post-arrest illness severity, survival and functionally favorable recovery.

RESULTS

Of 1054 subjects, 295 (28%) were prescribed an antiplatelet agent and 147 (14%) were prescribed an anticoagulant prior to arrest. In adjusted models, antiplatelet agents were associated with lower post-arrest illness severity (adjusted OR 0.50 95% CI 0.33-0.77), greater odds of survival to discharge (adjusted OR 1.74 95% CI 1.08-2.80) and greater odds favorable functional outcome (adjusted OR 2.11 95% CI 1.17-3.79). By contrast, anticoagulation via any agent was not associated with illness severity, survival to discharge or favorable outcome.

CONCLUSION

Preventing intra-arrest and post-arrest microvascular thrombosis via antiplatelet agents could represent a novel therapeutic target to improve outcomes after OHCA.

The influence of targeted temperature management on the pharmacokinetics of drugs administered during and after cardiac arrest: a systematic review

OBJECTIVE

Pharmacokinetic parameters of drugs are widely investigated under normothermic conditions and normal hemodynamic parameters. The European Resuscitation Council recommends the use of targeted temperature management (TTM) with a target temperature of 34 °C in cardiac arrest (CA) patients. The aim of this literature review is to investigate the influence of CA combined with TTM on the pharmacokinetics of drugs. Results of preclinical and clinical studies are compared with each other. Only the most important drugs, administered during CA in emergency setting, were studied.

METHODS

A literature search was conducted within PubMed and Google Scholar. The search terms included 'therapeutic hypothermia', 'TTM', 'drug metabolism', 'pharmacokinetics during hypothermia', 'cardiac arrest/etiology'. In Pubmed, MeSH-terms were also included: 'myocardial infarction/therapy', 'heart arrest/complications' and 'hypothermia'. To search for preclinical studies: the search terms 'pigs' and 'swine' were used. After the primary shift of relevant findings, further articles were found through references of these (snowballing method), as well as through related articles as suggested by the databases.

RESULTS

Due to the reduced cardiac output during TTM, most of the distribution volume ([Formula: see text]) of drugs included in this literature study is decreased. Only the [Formula: see text] of chlorzoxazone in CA rats and midazolam in non-CA patients are significantly increased during respectively deep and mild hypothermia. The renal, hepatic and biliary clearance of drugs administered during CA/TTM/hypothermia are decreased.

DISCUSSION

The combination of a decreased [Formula: see text] and a decrease in the metabolization/excretion of drugs during CA/TTM result in higher plasma concentrations compared to the plasma concentrations during CA without TTM.

Double Bolus Thrombolysis for Suspected Massive Pulmonary Embolism during Cardiac Arrest

More than 70% of cardiac arrest cases are caused by acute myocardial infarction (AMI) or pulmonary embolism (PE). Although thrombolytic therapy is a recognised therapy for both AMI and PE, its indiscriminate use is not routinely recommended during cardiopulmonary resuscitation (CPR). We present a case describing the successful use of double dose thrombolysis during cardiac arrest caused by pulmonary embolism. Notwithstanding the relative lack of high-level evidence, this case suggests a scenario in which recombinant tissue Plasminogen Activator (rtPA) may be beneficial in cardiac arrest. In addition to the strong clinical suspicion of pulmonary embolism as the causative agent of the patient's cardiac arrest, the extremely low end-tidal CO2 suggested a massive PE. The absence of dilatation of the right heart on subxiphoid ultrasound argued against the diagnosis of PE, but not conclusively so. In the context of the circulatory collapse induced by cardiac arrest, this aspect was relegated in terms of importance. The second dose of rtPA utilised in this case resulted in return of spontaneous circulation (ROSC) and did not result in haemorrhage or an adverse effect.

Thrombolysis during extended cardiopulmonary resuscitation for autoimmune-related pulmonary embolism

BACKGROUND

Massive pulmonary embolism (MPE) and acute myocardial infarction are the two most common causes of cardiac arrest (CA). At present, lethal hemorrhage makes thrombolytic therapy underused during cardiopulmonary resuscitation, despite the potential benefits for these underlying conditions. Hypercoagulability of the blood in autoimmune disorders (such as autoimmune hemolytic anemia) carries a risk of MPE. It is critical to find out the etiology of CA for timely thrombolytic intervention.

METHODS

A 23-year-old woman with a 10-year medical history of autoimmune hemolytic anemia suffered from CA in our emergency intensive care unit. ECG and echocardiogram indicated the possibility of MPE, so fibrinolytic therapy (alteplase) was successful during prolonged resuscitation.

RESULTS

Neurological recovery of the patient was generally good, and no fatal bleeding developed. MPE was documented by CT pulmonary angiography.

CONCLUSIONS

A medical history of autoimmune disease poses a risk of PE, and the causes of CA (such as this) should be investigated etiologically. A therapy with alteplase may be used early during cardiopulmonary resuscitation once there is presumptive evidence of PE. Clinical trials are needed in this setting to study patients with hypercoagulable states.

Successful use of intra-arrest thrombolysis for electrical storm due to acute myocardial infarction

Acute vascular thrombotic disease, including acute myocardial infarction and pulmonary embolism, accounts for 70% of sudden outpatient cardiac arrest. The role of intra-arrest thrombolytic administration aimed at reversing the underlying cause of cardiac arrest remains an area of debate with recent guidelines advising against routine use. We present a case of prolonged refractory ventricular fibrillation electrical storm in a patient who demonstrated intra-arrest electrocardiographic and sonographic markers confirming acute myocardial infarction. Return of spontaneous circulation was rapidly achieved after rescue intra-arrest bolus thrombolysis.Highlights of this case are discussed in the context of the current evidence for thrombolytic therapy in cardiac arrest with specific attention to the issue of patient selection.