Anatomy Review: Blood Flow in the Heart

Right Atrium –> Right Ventricle –> Pulmonary Artery –> Lungs –> Left Atrium –> Left Ventricle –> Aorta –> Body

Memory Tip: deoxygenate blood is received on the right-side of the heart, and oxygenated blood leaves from the left-side of the heart. 

My heart skip skips a beat


The pause is to allow the atria to fully empty into the ventricle.

Heartbeat on an ECG trace

P Interval (Ventricular Diastole)

  • Atria and ventricles are relaxed
  • blood is flowing into the atria from the veins. 
  • Atrial pressure increases above that of the ventricle, AV valves open allowing blood to flow into the ventricle

P Wave (Atrial Systole) P-Q

Signal transduction from SA to AV nodes. 

  • SA node fires 
  • Atria contract causing atrial systole 
  • which forces all blood into the ventricles
  • emptying the atria.

Q Interval (End of Ventricular Diastole)

Depolarisation of interventricular (IV) septum 

  • AV valves remain open - all remaining blood squeezed into the ventricles. 
  • impulse from the SA node reaches the AV node 
  • which spreads the signal throughout the walls of the ventricles via bundles of His and Purkinje fibres
  • R peak is the end of ventricular diastole and the start of systole.

R Interval (Ventricular Systole)

Ventricular contraction

  • All blood is now within the ventricles
  • so pressure is higher than in the atria - AV valves close
  • ventricles start to contract although pressure is not yet high enough to open the SL (semilunar) valves

ST Segment (Ventricular Systole)

Ventricular contraction

  • Pressure increases until it equals Aortic pressure,
  • SL valves open
  • blood is ejected into the Aorta (and pulmonary artery) as ventricles contract
  • At this time the atria are in diastole and filling with blood returning from the veins.
  • plateau in ventricular arterial pressure

T Wave (Ventricular Diastole)

T= moment of Ventricular repolarisation immediately before ventricular relaxation

  • Ventricles relax
  • ventricular pressure is once again less than the aortic pressure 
  • so SL valves close

“Heart in a Box”

Transmedics Organ Care System:

Doctors call it a “beating heart transplant,” but it’s more commonly known as “heart in a box.” In the new method, doctors use a machine to keep a transplanted heart viable outside a patient’s body for up to 12 hours. The machine pumps oxygenated blood through the heart, keeping it in good condition longer.It was life-saving for DeStefano, New England’s first patient. The mother of two hopes to be home from Massachusetts General Hospital next week.Right now, about half of all donor hearts are wasted with the current method of putting them on ice because that can only keep the heart useable for four hours.

“Heart in a box” transplants are common in Europe. The device was created by Andover company TransMedics Inc.

–Source: The Boston Channel, 2012

The cardiac cycle is a term referring to all or any of the events related to the flow or blood pressure that occurs from the beginning of one heartbeat to the beginning of the next. The frequency of the cardiac cycle is described by the heart rate. Each beat of the heart involves five major stages. The first two stages, often considered together as the ventricular filling stage, involve the movement of blood from atria into ventricles. The next three stages involve the movement of blood from the ventricles to the pulmonary artery (in the case of the right ventricle) and the aorta (in the case of the left ventricle).

The first, “early diastole,” is when the semilunar valves close, the atrioventricular (AV) valves are open, and the whole heart is relaxed. The second, “atrial systole,” is when the atrium contracts, and blood flows from atrium to the ventricle. The third, “isovolumic ventricular contraction,” is when the ventricles begin to contract, the AV and semilunar valves close, and there is no change in volume. The fourth, “ventricular ejection,” is when the ventricles are empty and contracting, and the semilunar valves are open. During the fifth stage, “Isovolumic ventricular relaxation,” pressure decreases, no blood enters the ventricles, the ventricles stop contracting and begin to relax, and the semilunar valves close due to the pressure of blood in the aorta.


Home is where the heart is…

…and when you apply this stunning anatomy themed wallpaper to your study/living room/love nest then the age old adage could not be more appropriate.

Aorta have this in the office but in the meantime, while I save up some pennies, bring your own walls to life by visiting the designer and retailer of these unique works of heart at the anatomyboutique



Happy Nurses Week.

To the student nurses, who are just getting their feet wet and wondering what they’re in for.

For the new grad nurses, whose feet are wet, are still wondering what they’re in for and I’m sorry but what is this on my shoe?

For the experienced nurses, who know better than to look at their shoes any more.

For ortho nurses, who can wrangle anyone into a brace and know how to get you to the bathroom when you’re in a knee immobilizer, a shoulder immobilizer, and two wrist splints.

For cardiac nurses, who can read a rhythm strip from a mile away, are no strangers to pacer pads, and aren’t worried until your run of Vtach hits 20 beats.

For post op nurses, who can identify every drain you know and a few you don’t, who can pop stitches and staples out in 10 seconds without making you flinch, and change a surgical dressing in their sleep.

For med-surg nurses, who will handle the highest ratios and become pros at doling out 120 pills before 9am. 

For renal nurses, OR nurses, emergency nurses, observation nurses, palliative and hospice care nurses, home health nurses, wound nurses, PICC nurses, infusion nurses, clinic nurses, nurse practitioners, nursing professors, oncology nurses, critical care nurses, neuro nurses, and the literal hundreds of other nursing specialties I can’t name.

Thank you for all that you do, and all that you will do.