What is the formula for correcting the QT interval for heart rates?
QTc = QT / √RR
After adjustment for heart rate using the Bazett formula, the corrected QT interval (QTc) is considered prolonged if it is more than 440 msec in men and 460 msec in women.
Bazett HC. An analysis of the time-relations of electrocardiograms. Heart 7:353, 1920.
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How does one evaluate the severity of the mitral stenosis with auscultation?
The shorter the S2 to opening snap (S2-OS) interval, the more severe the mitral stenosis. Higher left atrial pressure in early diastole will snap the valve open faster than a lower pressure situation.
The higher the intensity and the longer the duration of the rumble in diastole does correlate with the severity of the stenosis. But these qualities are more dependent on flow i.e. cardiac output. A decreasing cardiac output in the presence of a great degree of mitral stenosis might actually make a murmur softer than expected.
What are the other conditions that can mimic a mitral stenosis diastolic murmur?
- Carey-Coombs murmur of acute rheumatic fever is a sign of active mitral valvulitis
- Soft, early diastolic murmur usually varies from day to day.
- Higher pitch than the diastolic rumbling murmur of established mitral stenosis.
- Pure severe mitral regurgitation
- Increased flow across the valve
- Sometimes with a short diastolic murmur with a S3
- Left atrial myxoma
- Tumor plop
- Graham Steel murmur of pulmonary regurgitation
- Increases with inspiration
- Austin-Flint murmur
- A presystolic (late diastolic) murmur in patients with aortic insufficiency
- The aortic regurgitant jet of blood keeps the anterior mitral leaflet from its full diastolic excursion.
Which special maneuvers can augment the intensity of aortic insufficiency murmur?
Aortic insufficiency is best heard at the left lower sternal border with the patient leaning forward and in full expiration. The intensity of the murmur can increased by:
- Transient arterial occlusion:
By inflating blood pressure cuffs on both arms 40 mmHg above the systolic pressure for 20 seconds
Both of these maneuvers increase the afterload which increase the intensity of the murmur.
Which are the classic peripheral signs described in aortic insufficiency that can help in assessing the severity of this valvular heart condition?
- Duroziez’s Sign:
To and fro murmur when stethoscope is pressed over the femoral artery.
- Hill’s Sign:
In severe aortic insufficiency, the popliteal pressure is >= 20 mmHg
- Carotid shudder
- De Musset’s sign:
- Head bobbing sign, best seen in patients who are sitting or standing quietly.
- Alfred De Musset is one of the greatest French poets of the 19th century with presumably luetic aortic insufficiency.
- Corrigan’s pulse = Watson’s water hammer pulse:
- Peripheral manifestations of wide pulse pressure
- Also seen in PDA.
- Pulse pressure:
- Of little use in assessing the degree of aortic insufficiency in any patient
- Correlate little with prognosis
- Diastolic pressure of at least 70 mmHg and pulse pressure of less than 40 mmHg exclude moderate or severe AI but the contrary is not true.
- Rosenbah’s sign:
Hepatic pulsation, a late manifest ion of severe AI
- Gehard’s sign:
Spleenic pulsation, detected only if the spleen is enlarged for another reason.
- Becker’s sign:
Visible pulsations of the retinal arterioles
- Mueller’s sign:
- “Piston shot” sounds:
- Heard in 45 % of very severe AI. Also seen in other high stroke volume
- e.g. anemia and hyperthyroidism
- Traube’s sounds:
Femoral double sound elude by compressing the femoral artery with a finger distal to the stethoscope head with just the correct amount of pressure.
- Quincke’s sign (Of no diagnostic value):
- Quincke’s pulse seen by exerting on the edge of the nail, a pressure that is greater than the diastolic but less than the systolic.
- With each heart beat, a forward and backward movement of the margin between the red and the clear zone.
- Originally described by Quincke’s in himself and seen in normal persons usually.
- Mayne’s sign (Of no diagnostic value):
- Decrease in the indirect diastolic blood pressure of 15 mm Hg when the arm is held above the head as compared with the baseline diastolic blood pressure taken with the arm at the level of the heart.
- Occurs in 65% of normal persons.