Means and method for the detection of cardiac events

Abstract

Disclosed is a system for the detection of cardiac events that includes an implanted device called a cardiosaver, a physician's programmer and an external alarm system. The system is designed to provide early detection of cardiac events such as acute myocardial infarction or exercise induced myocardial ischemia caused by an increased heart rate or exertion. The system can also alert the patient with a less urgent alarm if a heart arrhythmia is detected. Using different algorithms, the cardiosaver can detect a change in the patient's electrogram that is indicative of a cardiac event within five minutes after it occurs and then automatically warn the patient that the event is occurring. To provide this warning, the system includes an internal alarm sub-system (internal alarm means) within the cardiosaver and/or an external alarm system (external alarm means) which are activated after the ST segment of the electrogram exceeds a preset threshold.

What is claimed is: 
     
         1 . A system for detecting cardiac events in a human patient, the system including:
 at least two electrodes for obtaining an electrical signal from the patient's heart;   a processor configured to detect at least a first type of cardiac event and a second type of cardiac event by processing the electrical signal from the patient's heart;   a patient alerting mechanism connected to the processor for receiving a first or second event activation signal from the processor dependent on said processor detection of said first or second type of cardiac event based upon event severity, the patient alerting mechanism being activated by said first or second activation signal, the patient alerting mechanism configured for:
 responsive to said first activation signal, emitting a first alarm signal having a first number of pulses within a first period of time defining an initial alarm on-period; 
 responsive to said second activation signal, emitting a second alarm signal having a second number of pulses within a second period of time defining said initial alarm on-period, said first number of pulses being different than said second number of pulses; 
 the initial alarm-on period being followed by a respective alarm off-period of time devoid of pulses, the patient alerting mechanism being further configured to only emit a reminder alarm signal responsive to the first type of cardiac event following the initial alarm off-time period of time for a predetermined alarm period of time, said reminder alarm period of time being greater than said first and second periods of time, said patient alerting mechanism including a disabling mechanism for disabling said reminder alarm. 
   
     
     
         2 . The system of  claim 1  where the reminder alarm signal which lasts for the reminder alarm on-period is repeated periodically, the time between the periodic reminder alarm signals being an additional alarm off-period. 
     
     
         3 . The system of  claim 2  where the periodic reminder alarm on-period is greater than 15 minutes. 
     
     
         4 . The system of  claim 2  where the periodic reminder alarm on-period is less than 5 hours. 
     
     
         5 . The system of  claim 2  where the alarm off-period after the initial alarm on-period has a different time duration as compared to the time duration of the alarm off-period after a periodic reminder alarm on-period. 
     
     
         6 . The system of  claim 1  where the alarm off-period of time is at least twice as long as the alarm on-period. 
     
     
         7 . The system of  claim 1  where the alarm on-period is less than 10 minutes. 
     
     
         8 . The system of  claim 1  where at least a portion of the system is implanted in the human patient. 
     
     
         9 . The system of  claim 1  where the cardiac events detected by the system include acute myocardial infarction. 
     
     
         10 . The system of  claim 1  where the cardiac events detected by the system include ischemia at an elevated heart rate. 
     
     
         11 . The system of  claim 1  where the cardiac events detected by the system include low heart rate. 
     
     
         12 . The system of  claim 1  where the cardiac events detected by the system include excessively high heart rate. 
     
     
         13 . The system of  claim 1  where the cardiac events detected by the system include arrhythmias.