Duration of Atrial and Ventricular Phases

• Atrial systole (As): Approximately 0.1 seconds.

• Atrial diastole (Ad): Approximately 0.7 seconds.

• Ventricular systole (Vs): Approximately 0.3 seconds.

• Ventricular diastole (Vd): Approximately 0.5 seconds.

The total time for one cardiac cycle is about 0.8 seconds at a normal heart rate (~75 beats per minute).

Relationship Between Durations

Adding atrial systole and diastole gives:

_{$$As+Ad=0.1+0.7=0.8\text{ seconds}$$}

Adding ventricular systole and diastole gives:

_{$$Vs+Vd=0.3+0.5=0.8\text{ seconds}$$}

Thus, the total durations of atrial systole plus diastole equal the total durations of ventricular systole plus diastole, both matching the cardiac cycle duration:

_{$$As+Ad=Vs+Vd$$}

Correct Option

The correct equation is:

(1) As + Ad = Vs + Vd

Summary Table

Additional Information

• The cardiac cycle duration shortens with increased heart rate, mainly by shortening diastole.

• The coordination between atrial and ventricular timings ensures efficient ventricular filling and blood ejection.

• Understanding this timing relationship is essential clinically for diagnosing and managing cardiac dysfunctions.