[SCD-FORUM] 69E RE: Cardiorespiratory arrest and sudden cardiac death. Dr. Perez Riera

[SCD Symposium]

Dear Miguel Angel Sanchez Verduzco from Guadalajara Jalisco Mexico.  
Here Andrés Ricardo Pérez Riera from Sao Paulo Brazil answer.
Sudden death (SD) is defined as a death that occurs suddenly,  
develops during an unpredictable course, and is due to natural or  
unnatural causes. Although there is no universally standardized  
definition on how "sudden" a SD is, WHO defines SD as a death that  
occurs within 24 hours after the onset of symptoms.

Sudden Cardiac Death (SCD) is defined as unexpected natural death due  
to cardiac causes, heralded by abrupt loss of consciousness within  
one hour after the onset of symptoms in a person without any prior  
condition that would appear fatal(1). SCD is the sudden, abrupt loss  
of heart function (ie, cardiac arrest) in a person who may or may not  
have been diagnosed with heart disease. The time and mode of death  
are unexpected. It occurs instantly or shortly after the onset of  
symptoms. Out-of-hospital SCD is a frequent cause of death. Survival  
rates remain low despite increasing efforts in medical care. Recently  
information on cases of out-of-hospital SCD was collected in the  
Berlin, Germany, and emergency medical system via a questionnaire by  
Muller et al.(2)  Bystander interviews were performed by the  
emergency physician on scene immediately after declaration of death  
or return of circulation. Of 5831 rescue missions, 406 involved  
patients with presumed cardiac arrest. 66% had a known cardiac  
disease. In 72%, the arrest occurred at home, and in 67%, it occurred  
in the presence of an eyewitness. Information on symptoms immediately  
preceding the arrest was available in 80% of all 406 patients.  
Typical angina was present for a median of 120 minutes in 25% of the  
274 patients with witnessed arrest and in 33% with a symptom duration  
of less than 1 hour. The authors conclude that SCD occurs most often  
at home in the presence of relatives and after a longer period of  
typical warning symptoms. Although the much-hailed use of public  
access external defibrillation is supported by several studies, the  
present results raise the question of whether educational measures  
and targeted educational programs tailored for patients at risk and  
their relatives should have a higher priority.
  SCD is a dramatic and/or spontaneous death that is thought to be  
(and usually is) caused by a heart condition and may have been  
brought on by exercise.
The mechanisms of SCD are the following: 1)       VF; 2)       VT and  
ventricular flutter with subsequent VF; 3)       TdP followed by VF;  
4)       Bradyarrhythmias and 5)       Asystolic arrest.
White the main risk factor is the presence of coronary artery disease 
(CAD), any organic or functional disease of the heart can predispose  
for SCD.
SCD (also called sudden cardiac arrest (SCA) or cardiovascular  
collapse,) is death resulting from an abrupt loss of heart function.  
The victim may or may not have diagnosed heart disease. The time and  
mode of death are unexpected. It occurs within 60 minutes after  
symptoms appear in a person with known or unknown cardiac disease in  
whom no previously diagnosed fatal condition is apparent. The most  
common underlying reason for patients to die suddenly from SCA  is CHD.
Approximately half of all cardiac deaths can be classified as SCDs.
SCD occurs as the first expression of cardiac disease in many  
individuals presenting as out-of-hospital patients with SCA.
To evaluate the risk of SCD noninvasive (Holter, echocardiography,  
exercise test, SA-ECG, MTWA, and often invasive PES tests are necessary.
The therapy is based on drugs (mainly beta blockers and amiodarone),  
coronary revascularization, catheter ablation techniques and the  
implantation of a CDI. The latter appears to be the most promising  
approach(3).
Sudden Arrhythmia Death Syndrome (SADS) In about 1 in every 20 cases  
of SCD, no definite cause of death can be found, even after the heart  
has been examined by an expert cardiac pathologist. This is then  
called Sudden Arrhythmic Death Syndrome or SADS. (In the past it has  
also been called Sudden Adult Death Syndrome or Sudden Death Syndrome  
but, because it affects children too, the term Sudden Arrhythmic  
Death Syndrome is now used.) It is thought that cot death (Sudden  
Infant Death Syndrome, or SIDS) may be partly due to the same causes  
responsible for SADS.

SADS is a disorder of the electrical system of the heart that can  
lead to the death of apparently healthy people without any warning.  
The condition is caused by dysfunction ion channels.  These channels  
control the flow of ions like Ca++, Na+ and K+. The flow of these  
ions in and out of the cells produces the electrical activity of the  
heart.  Abnormalities of these channels can be acquired or  
inherited.  The acquired form is caused by certain medications or  
physiopatological conditions.

References

1)       Zheng ZJ, Croft JB, Giles WH, et al. Sudden cardiac death in  
the United States, 1989 to 1998. Circulation. 2001; 104: 2158–2163.
2)       Muller D, Agrawal R, Arntz HR. How sudden is sudden cardiac  
death? Circulation. 2006; 114:1146-1150.
3)       Evequoz D, Zuber M, Erne P.Sudden cardiac death: definition,  
mechanisms and risk factors Synonyms and related keyword: sudden  
arrest: Schweiz Rundsch Med Prax. 1996; 85:188-196.
All the best
Andrés Ricardo Pérez Riera
Chief of Electro-Vectocardiology Sector of the Discipline of   
Cardiology, ABC Faculty of Medicine (FMABC), Foundation of ABC  
(FUABC) - Santo André -  Sao Paulo - Brazil. Rua Sebastiao Afonso   
885 - Zip Code: 044417-100- Jardim Miriam   S.P  Brazil


--
Dr. Sergio Dubner
President of Scientific Committee

Dr. Edgardo Schapachnik
President of Steering Committee



>
> I can't see hardly any complication, not even semantic, in what we  
> consider cardiac arrest or better, cardiorespiratory arrest,  
> whichever the cause. We may simply consider that any patient that  
> requires cardiorespiratory reanimation is because he/she has: lack  
> of effective cardiac output.
>
> Dr. Miguel Angel Sanchez Verduzco
> medicina intensiva. Guadalajara jalisco México
>>
>> From a certain point of view, cardiac arrest is the time of death,  
>> although we all know there is a margin between brain death,  
>> legally considered in many countries as "death" proper, and  
>> cardiac arrest or else, tachyarrythmias that condition low output.  
>> It would be necessary to differentiate also VT/VF from electrical  
>> activity with no pulse, or asystole as cause of death. We know  
>> that on many occasions, they are a continuum that we attempt to  
>> stop with different interventions that are variably successful  
>> according to the opportunity and efficacy.
>> From my personal point of view, the difference may be more  
>> semantic than practical, due to the great amount of variables to  
>> take into account: do we consider cardiac arrest as the  
>> disappearance of pulse? However, many times there is VT or VF, why  
>> can we start CPR even when there are still slow pulses (escape  
>> rhythms or AV blocks in ECG)? Again we are involved in a  
>> discussion of terms very hard to define because of the number of  
>> pathophysiological concepts and mostly, due to the "dynamics" of  
>> events and their sequences. What do experts think?
>>
>> Enrique Asensio L.
>> México
>>
>>
>>>
>>> Dear colleagues,
>>> I am writing to this list because I would to have some concepts  
>>> clarified to me regarding the subject of discussion.
>>> I have looked through several articles, books and journals, and  
>>> they are not clear in this sense. For instance: the Spanish  
>>> guidelines for CPR mention that there is a very narrow and  
>>> arbitrary limit between the concepts of cardiorespiratory arrest  
>>> and sudden cardiac death, leaving one for statistic limits, and  
>>> the cardiorespiratory arrest as a clinical approach of the problem.
>>> My question for the experts:
>>> Is there some way of defining both concepts, or do they overlap  
>>> in such a way that they can be used without distinction in  
>>> related studies and papers?
>>> Other authors point out “reanimation from sudden cardiac death”.
>>> Could it be reanimation from a cardiac arrest? Is it not death  
>>> precisely that, “death”?
>>>
>>> I hope you can clarify this dilemma for me, and thanking you in  
>>> advance,
>>>
>>> Dr. Oscar Ruiz Ropero
>>> Intensivista
>>> Hospital General Docente. Guantanamo. Cuba.

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