In Mitrial stenosis if LAP increases the pressure gradient increases which will increase the intensity and duration of murmur?
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mitral stenosis diastolic murmur loudness duration left atrial pressure gradient
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Mostly yes, with an important qualification.
In mitral stenosis, if left atrial pressure rises while left ventricular diastolic pressure remains relatively unchanged, the LA-LV transmitral pressure gradient increases. This raises flow velocity and turbulence across the stenotic mitral valve, so the mid-diastolic rumbling murmur tends to become louder.
A greater and more persistent gradient also means flow continues across the valve for more of diastole, so the murmur can become longer in duration. A longer diastolic rumble generally suggests more severe mitral stenosis. Goldman-Cecil Medicine, p. 688.
However, murmur intensity depends on flow as well as gradient:
- Increased flow such as exercise, fever, pregnancy, or tachycardia can make it louder.
- Low cardiac output can make even severe MS sound soft.
- Tachycardia may increase the gradient/intensity but shortens diastole, so the murmur may be shorter, not longer.
- Atrial contraction produces presystolic accentuation in sinus rhythm; this disappears in atrial fibrillation.
So the best statement is: higher LAP usually increases the transmitral gradient and tends to make the murmur louder; duration increases when the gradient persists longer through diastole, but this is modified by heart rate and transmitral flow.
What are isometric exercises and what is there effect on afterload
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isometric exercise increases blood pressure systemic vascular resistance afterload physiology
Isometric exercise means contracting a muscle without changing its length or moving a joint.
Examples:
- Sustained handgrip
- Holding a heavy object still
- Plank or wall-sit
- Pushing against an immovable object
Effect on afterload
Isometric exercise, particularly handgrip, increases afterload.
During a sustained contraction, the contracting muscle compresses its blood vessels. This, together with sympathetic activation, raises systemic arterial pressure and systemic vascular resistance. The left ventricle must therefore eject blood against a higher aortic pressure, which is increased afterload.
Afterload = the pressure/resistance against which the ventricle ejects blood.
Clinical auscultation relevance
Handgrip tends to increase murmurs of:
- Mitral regurgitation
- Aortic regurgitation
- Ventricular septal defect
It tends to decrease the murmur of:
- Hypertrophic obstructive cardiomyopathy
- Mitral valve prolapse
The textbook specifically describes handgrip isometric exercise as a maneuver that increases afterload. Fuster and Hurst's The Heart, 15th Edition, Dynamic Auscultation.
Is squatting also isometric exercise
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squatting maneuver preload afterload dynamic auscultation physiology
Not usually. Squatting down and rising are dynamic movements, because muscles shorten and lengthen while the hip and knee joints move.
But holding a squat position such as a wall-sit is an isometric exercise: the leg muscles contract without appreciable joint movement.
In cardiac bedside maneuvers, “squatting” usually means moving from standing to a squatting position. Its important hemodynamic effects are:
- Increases preload: leg compression and reduced venous pooling increase venous return.
- Increases afterload: systemic vascular resistance and arterial pressure rise.
So, squatting is not classified as the same pure isometric maneuver as sustained handgrip, but it can involve isometric muscle contraction and it increases both preload and afterload. Fuster and Hurst's The Heart, 15th Edition, Dynamic Auscultation.
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