Sudden cardiac death

Sudden cardiac death (SCD) covers a range of conditions in which there is a cardiac arrest or ineffective heart pumping within one hour of the onset of symptoms, often without previous indication of heart disease. It may be as sudden as an apparently healthy victim collapsing in mid-sentence. All SCD is a subset of acute coronary syndrome.

With quick response and aggressive treatment, it is not necessarily fatal, although the survival rate, just as with the television-derived expectation that cardiopulmonary resuscitation is reliably lifesaving, is dismal. Without aggressive treatment, however, the chances of survival are nonexistent.

It accounts for perhaps half of cardiac deaths, and is most likely due to an abnormal tachycardia leading to ineffective pumping action of the heart.

Risk factors on history

It is a bit confusing to describe the conditions below as "history", because they may not have been symptomatic, and the patient may only be aware of them if he or she is in an aggressive testing program, or if they have produced symptoms.

Familial history is less predictive, but awareness of any of these conditions in a close relative may raise risks

• Coronary heart disease
• Dilated cardiomyopathy
• Hypertrophic cardiomyopathy
• Valvular disease
• Long QT syndrome
• Wolff-Parkinson-White syndrome (WPW)
• Brugada syndrome
• arrhythmogenic right ventricular cardiomyopathy

Immediate evaluation

To some extent, the emergency room or advanced paramedic evaluation is a form of triage. One scoring assigns points:

• Emergency department (ED) systolic blood pressure great than 90 mm Hg: 1 point
• Time to return of spontaneous circulation (ROSC) less than 25 minutes: 1 point
• Neurologically responsive: 1 point

Maximum score is three points. Coma gives a score of zero points.

• Patients with a 3 point score can have a 89% chance of neurologic recovery and an 82% chance of survival to discharge.
• Patients with low scores are unlikely to survive, even with early invasive management
• Indication of poor oxygen flow to the brain, even with scores of 0-2, have very poor survival even with invasive management.

Management

Obviously, speed is essential, beginning with cardiopulmonary resuscitation, moving to defibrillation if the arrythmia is responsive to it or to cardioversion where appropriate, and administering the appropriate drugs. When indicated, treatments such as a left ventricular assist device may buy time for more definitive care.

Definitive treatment involves correcting the source of the cardiac event. If the problem was caused by abnormal pacemaker tissue, radiofrequency ablation or surgical intervention may be needed to correct the problem. Revascularization procedures such as coronary artery bypass grafting (CABG) or percutaneous transcutaneous coronary angioplasty may be warranted. Electrical assistive devices such as pacemakers or implantable cardioverter-defibrillators may be implanted.