The cardiac cycle, CVP, arterial waveforms

Systole:

1. Isovolaemic ventricular contraction (The period between closure of the mitral valve and opening of the aortic valve). This occurs immediately following the R wave.
2. Early (fast) ejection phase (The period of active myocardial contraction)
3. Late (slow) ejection phase (Ventricular contraction continues due to inertia imparted to the ventricular wall and contents). This begins at the beginning of the t-wave.

Diastole:

1. Isovolaemic relaxation (The period between closure of the aortic valve and opening of the mitral valve). This corresponds with the end of the t-wave.
2. Early (elastic) diastole (rapid ventricular filling)
3. Diastasis (slower ventricular filling)
4. Atrial systole. This occurs at the p-wave (RA) or right after (LA).

Timing differences between the left and right heart:

1. The right atrium contracts before the left (because of the SA node's location just inferior to the SVC in the RA)
2. The RV isovolaemic contraction is shorter (because the PADP is so low), so the pulmonic valve opens before the aortic valve
3. Right isovolaemic contraction is also shorter

A wave: Right atrial contraction.

C wave: The right ventricle contracts. The tricuspid valve cusps balloon into the RA

X descent: The ventricle contracts, making the floor of the atrium drop, increasing RA volume

V wave: distension of the RA from filling during late ventricular systole

Y descent: the triscupid valve opens, blood rushes into the empty RV

AF: no A waves.

Triscuspid regurgitation: Increased pressure during all of ventricular systole. Therefore fused CV waves with loss of the X descent.

AV dissociation: Cannon a-waves (atrial contraction against a closed tricuspid valve. Occurs in junctional rhythms, CHB, ventricular pacing, ventricular ectopics, and VT.

Constrictive pericarditis: This sets the maximum volume of the heart to some low valve. That means that the end systolic volume will be very low, and the ventricles will be hungry hungry hungry for some blood, resulting in very steep X and Y descents:

Tamponade: obliteration of the y-descent (because drainage into the RV is so impaired) and a markedly elevated CVP.

Key differences

1. Lower pulse pressure and higher MAP in the aorta due to windkessel (hydraulic accumulator) effect
2. Later systolic peak in the radial artery due to pressure wave travelling through the arteries at 100 m/s
3. Higher systolic peak due to distal pulse amplification
4. Steeper upstroke due to lack of compliance in the radial artery
5. High frequency components smoothed by damping
6. Diacrotic notch from reflected wave from the arterioles