Although none of the editors of InsideSurgery.com have participated in his care, we have noted the news reports that entertainer Michael Jackson has died of sudden cardiac arrest. He was 50.
Jackson, who became a controversial figure over the last 18 years of his life, had no previously reported cardiac disease.
Although invariably shocking to bystanders who witness a sudden cardiac death, the condition is distressingly common, comprisingly more than 50% of all cardiac deaths. Approximately 300,000 patients each year in the United States die of sudden cardiac arrest (aka heart attack, myocardial infarction and MI).
The formal definition of sudden cardiac arrest is an instantaneous collapse of the cardiovascular system within one hour of onset of symptoms. It is usually caused by a malignant arrhythmia such as ventricular fibrillation (VF), which is the unsynchronized quivering of the two heart ventricles with absence of a meaningful volume of blood being pumped to the brain.
V-fib, if left untreated, almost universally leads to cardiac asystole, which is complete absence of cardiac contractility.
Approximately 80% of patients who suffer sudden cardiac death (SCD) have underlying coronary artery disease. About 15% have valvular disease, dilated cardiomyopathy (enlarged heart), or left ventricular hypertrophy (enlarged left ventricle.)
Risks factors include male sex (70% of sudden cardiac deaths occur in men) and vigorous activity, which increases the risk approximately 17 fold over normal daily activities. Additional factors include race (more prevalent in African Americans) and diabetes mellitus, as well as hypertension, tobacco use, and high serum cholesterol.
Many sudden cardiac arrest investigators also believe that certain medications such as amphetamines, cocaine, tricyclic antidepressants, antihistamines, diuretics, and angiotension converting enzyme inhibitors can precipitate sudden cardiac death.
The incidence of sudden cardiac death has dropped in recent years, likely due to the decrease in the incidence of coronary atherosclerotic disease.
The onset of sudden cardiac death occurs in a diurnal pattern, peaking in the hours between 7 AM and 10 AM and then in the late afternoon between the hours of 4 PM and 7PM. It is more prevalent in the colder, winter months that have fewer hours of daylight.
In addition, some investigators have hypothesized that there is a stress component in the onset of sudden cardiac death, perhaps explaining a spike in incidence in the post holiday period of January.
Despite the recent emphasis of having readily available defibrillators in many public places, the mortality of sudden cardiac arrest is high. Patients who suffer out-of-hospital sudden cardiac arrest have a 4 to 40% chance of surviving to hospital discharge.
Of those patients who do survive sudden cardiac arrest, 90% have emerged from their acute event and have good mental functioning by day three post-arrest; those who remain in a coma after 72 hours have a dismal prognosis.
The risk of a recurrent sudden cardiac arrest after survival of an initial event is 10 to 30%, even with aggressive therapy such as the initiation of beta-blockers, valvular repair, and coronary artery bypass.
The most important factor by far in determining overall survival after a sudden cardiac arrest is time to defibrillation, which can be administered by trained lay persons who have access to an AED or by medical professionals.
For every minute that passes from a witnessed sudden cardiac arrest to defibrillation, the chance of survival decreases by 7-10% if no cardiopulmonary resuscitation is given and 3-4% if CPR is administered.
What is little understood by the public is that defibrillation does not actually “restart” the heart but rather stuns the heart in an attempt to allow the normal pacemaker mechanism to function.
In all situations, cardiopulmonary resuscitation (CPR) must be undertaken immediately (without checking for a pulse) for a minimum of several minutes after a patient with sudden cardiac arrest is defibrillated.
This provides delivery of oxygenated blood to the brain and other organs during the interval that the heart is attempting to return to organized electrical activity.
Correctly performed CPR consists of chest compressions to a depth of 1.5 to 2 inches for thirty compressions, with two rescue breaths given at the end. Emergent transfer to a hospital is mandatory.
Meaningful chance of recovery diminishes very rapidly if a rhythm and discernable pulse is not established within 15-20minutes. Most professionals suspend resuscitative efforts if there are no correctable abnormalities and the patient is warm after about 25-30minutes from onset of resuscitation.