Setting: office
CC: “Here to check my pressure, Doc.”
VS: R: 12 breaths/minute; BP: 125/82 mm Hg; P: 75 beats/minute; T: 98.4°F
HPI: A 54-year-old woman with long-standing hypertension visits your office for her routine evaluation every 6 months. She generally feels well. She feels okay with ordinary efforts such as walking on flat surfaces or housecleaning. She has just transferred her care to you from one of your partners who retired.
PMHX:
Hypertension
MR
Medications:
Chlorthalidone
What murmur would you expect with the history of MR?
a. Pansystolic
b. Crescendo-decrescendo systolic
c. Diastolic decrescendo
d. Midsystolic extra sound with late murmur
e. Continuous “machinery” murmur
Answer a. Pansystolic
MR obscures both S1 and S2 sounds and can also be described as “holosystolic.” The crescendo-decrescendo murmur is either aortic stenosis or hypertrophic obstructive cardiomyopathy. A diastolic decrescendo murmur (choice c) is aortic regurgitation. The midsystolic extra sound with murmur is mitral valve prolapse. A continuous machinery murmur (choice e) is patent ductus arteriosus.
PE:
Chest: normal, no rales
Extremities: no edema
Cardiovascular: II/VI pansystolic murmur radiating to the apex
Initial Orders:
Echocardiogram
ECG
Chest x-ray
CHEM-7
As an office-based case of someone who is generally asymptomatic, you can bring your patient back to the office on CCS in 2 to 4 weeks after the initial visit. Nonacute chronic cases do not have precise parameters to guide the time interval between visits because it is not clear and therefore, you will not be graded on it.
Test Results:
Echocardiogram: moderate MR, EF 62%, LV end-systolic diameter 35 mm
Chemistry: normal
ECG: LV hypertrophy
What is the mechanism of LV hypertrophy?
a. Increasing wall thickness decreases wall tension according to the Laplace law.
b. Increasing wall thickness generates hypertension.
c. Wall thickness has no impact on the Laplace law.
d. Increasing radius will decrease the wall tension.
Answer a. Increasing wall thickness decreases wall tension according to the Laplace law.
Increasing LV wall thickness decreases wall tension.
Law of Laplace: Radius × Pressure = Wall Tension Wall Thickness
This is why decreasing BP will decrease wall tension as well. This is also why the radius of the LV chamber increases its rate of dilating once dilation begins. The bigger or wider the LV, the faster it will dilate. This is why BP has to be controlled before LV dilation occurs.
The wider a chamber is, the faster it widens.
Which is more accurate for assessing LV hypertrophy?
a. Transthoracic echocardiogram
b. MUGA (nuclear ventriculogram)
c. ECG
d. Catheterization
Answer a. Transthoracic echocardiogram
An echocardiogram is far more accurate than ECG for LV hypertrophy. The MUGA or nuclear ventriculogram assesses EF and does nothing to assess LV thickness. A nuclear ventriculogram is the single most accurate method of assessing EF. Catheterization looks at valve function and pressure gradients but does not evaluate LV wall thickness.
Chlorthalidone inhibits sodium uptake in the distal tubule.
When the patient is lying on a table and you lift the patient’s legs in the air, the murmur of MR increases in intensity. What is the mechanism?
a. Increasing afterload
b. Increased myocardial oxygen consumption
c. Decreased atrial filling pressure
d. Pooling blood in abdomen
e. Increased venous return/preload
Answer e. Increased venous return/preload
Leg raises and squatting from a standing position will increase venous return to the heart and increase filling pressure. MR, AR, MS, and AS will all increase in loudness or intensity with maneuvers such as these, which put more blood in the heart.
What is the best medical management of the MR?
a. No changes are needed; continue chlorthalidone.
b. Use endocarditis prophylaxis when bloody dental work is planned.
c. Add a beta-blocker.
d. Switch chlorthalidone to lisinopril.
e. Add spironolactone.
f. Switch chlorthalidone to furosemide.
Answer d. Switch chlorthalidone to lisinopril.
Regurgitant cardiac lesions, such as MR and AR, are best managed with vasodilators such as ACE inhibitors, ARBs, or nifedipine. We think there is some benefit in decreasing the rate of progression of regurgitation.
None of these valvular lesions has sufficient turbulence to need endocarditis prophylaxis. Beta-blockers and spironolactone would offer no benefit for a person with a normal EF. There is no fluid overload, so switching to a loop diuretic offers nothing for this patient.
You stop chlorthalidone and start lisinopril. Advance the clock 1 to 2 weeks to check BP and for adverse effects of ACE inhibitors such as cough, angioedema, and hyperkalemia. On return 2 weeks later, the patient feels well and her BP is 118/78 mm Hg. You schedule an appointment 3 months into the future. BP is again well controlled. After another 3 months, you repeat the echocardiogram with these results: EF 55%, left ventricular end-systolic diameter 45 mm.
What is the effect on handgrip as an ausculatory maneuver on this patient?
a. It decreases venous return, softening the murmur.
b. It increases venous return, improving or softening the murmur.
c. It increases afterload, worsening the murmur.
d. Handgrip has no effect on regurgitant lesions.
Answer c. It increases afterload, worsening the murmur.
Handgrip is based on the patient squeezing the examiner’s hand. This increases afterload by compressing the arteries of the arm. This has an effect the opposite of that of an ACE inhibitor and will, therefore, worsen regurgitant lesions such as AR and MR. The volume of blood in the arm is too small to make a meaningful increase in venous return.
You schedule the patient to return for repeat echocardiogram in 3 months. On return, EF decreases from 55% to 50% and LV end-systolic diameter increases from 45 mm to 48 mm. The patient has no symptoms at rest or with usual exertion. She has been fully adherent to the lisinopril.
What is the right action?
a. Institute no change and instruct the patient to return for follow-up in 3 to 6 months.
b. Switch the ACE inhibitor to an ARB.
c. Add an ARB to the ACE inhibitor.
d. Refer the patient for catheter or surgical valve repair or replacement.
e. Add metoprolol to the patient’s medication regimen.
Answer d. Refer the patient for catheter or surgical valve repair or replacement.
Surgical repair or replacement of the mitral or aortic valve must be done for regurgitant lesions before the patient develops symptoms. Once the ventricle dilates, there is no way to reverse the dilation and that is why anatomic correction must be done when the EF starts to drop. Vasodilators cannot reverse LV dilation, they can only prevent it from occurring.
Criteria for Surgical Repair or Replacement
