Update (30/9/2015) : Correction made in the following sections : Manuevers increasing afterload, maneuvers decreasing afterload. Also, the summary table has been updated and corrected. Please review it again if you have already read it before.
It’s an interesting topic and very important too. Unfortunately it’s not given well in most places and given wrong in many books which adds to the confusion. Allow me to simplify this topic and make it easy to understand for you.
Let’s divide maneuvers into two types: 1) Basic, 2) Advanced (This classification is purely made up and has no clinical significance… it’s just to make it easy to remember)
BASIC MANEUVERS These include effect of inspiration and expiration…
1) INSPIRATION: Inspiration increase right-sided heart murmurs
2) EXPIRATION: Expiration increase left-sided heart murmurs
Mechanism: During inspiration, there is more negative intrathoracic pressure which pulls the venous blood from all over body into heart, also Right atrial pressure decreases during inspiration. All this combines to increase venous return (Preload) into Right side of heart. At the same time, during inspiration, as lung are expanding, pulmonary blood volume increases and there is decrease in blood flow from lungs into Left atrium. So basically, preload of Left side of heart decreases during inspiration. This is the reason, Right sided heart sounds and murmurs increase during inspiration and left sided heart sounds and murmurs decrease in intensity. During expiration, as intrathoracic pressure rises, the venous return from body decreases. Also, Right atrial pressure (which is closely associated with intrapleural pressure) increases. All this lead to decreased preload of Right side of heart. At the same time, lung deflation during expiration causes more blood to flow from lungs to Left atrium. This increases the preload of left side of heart. Therefore, during expiration, left sided heart sounds and murmurs increase in intensity while right sided murmurs decrease.
Exception : MVP and HOCM murmurs DO NOT increase on expiration
How to remember: “RILE” Right sided – Inspiration… Left sided – Expiration
ADVANCED MANEUVERS There are four important groups of maneuvers