IOTW 11/10/20

28M p/w biliary colic however reports PMHx of “dilated heart”. Bedside ECHO was performed…

  1. What are some EKG findings associated with the suspected diagnosis?
    • In the setting of hypertrophic cardiomyopathy, EKGs may often be nonspecific or normal. However, you may see a high voltage or LVH pattern and deep narrow “needle-like” Q waves in the inferolateral leads. There may also be deep T-wave inversions in the anterolateral leads.
  2. What LV wall thickness supports the diagnosis?
    • Unexplained wall thickness >1.5 cm in any myocardial segment. A septal:posterior wall thickness ratio can be measured. An abnormal ratio is >1.3 in normotensive patients and >1.5 in hypertensive patients. The ratio in the image above comes out to (3.1 cm/1.8 cm=) ~1.7 which is abnormal and should prompt further evaluation. Asymmetric septal hypertrophy may be present. In addition, the LV outflow tract diameter can be measured in the parasternal long view just proximal to the aortic valve to assess for obstruction. The LVOT normally measures 1.6 – 2.4 cm.
  3. What features of the mitral valve are associated with this?
    • Mitral regurgitation is sometimes present. You may also assess for systolic anterior motion (SAM) of the mitral valve to help assess for obstruction. To do this you would obtain an M-Mode waveform through the anterior mitral valve leaflet in parasternal long view similar to how you would assess for EPSS. The mitral valve would exhibit anterior excursion toward the interventricular septum during systole if this was present.
  4. If this patient presents in decompensated CHF, what are some considerations in the management in regards to…
    • Administering IV fluids?
      • Volume loading is essential to increase preload and you should be sure to adequately fluid resuscitate prior to considering pressors in order to avoid worsening of the LV outflow tract obstruction. Monitor carefully for signs of fluid overload.
    • Intubation?
      • If it is absolutely necessary and cannot be avoided, you want to take all precautions to maintain preload. Push dose phenylephrine should be mixed and readily available (1 mL of 10 mg/mL phenylephrine in 100 mL NS = 100 mcg/mL; may use 1-2 mL (100-200 mcg) q2-5 min). BVM ventilations should not be aggressively performed. Avoid high airway pressures.
    • Managing tachycardia?
      • Beta blockers are the mainstay especially if angina or dyspnea present. You can titrate to a resting heart rate of 60 bpm. Use with caution if there is sinus bradycardia or conduction abnormality. Verapamil is another option. You must avoid vasodilators such as nitrates and dihydropyridine CCBs such as nifedipine. Do not give digitalis. Have a low threshold to cardiovert if needed to maintain sinus rhythm, for example if there is atrial fibrillation.
    • Choice of vasopressors?
      • If hypotensive and decision is made to initiate pressors, goal is to increase afterload. Phenylephrine is probably the best pressor to start with and consider vasopressin if it is maxed and a second pressor is needed. To increase efficacy of your pressors, attempt to fix any acidosis if present. AVOID positive intotropes such as dobutamine, norepinephrine, epinephrine, and dopamine.
  5. What is the definitive treatment of this condition?
    • While an ICD +/- AV sequential pacing may be used to treat ventricular dysrhythmias, the definitive treatment of LV outflow tract obstruction is myomectomy or resection of outflow tract.
  6. If the patient cannot be admitted, what discharge instructions should be provided?
    • Important to avoid exertion. May be started on beta-blocker from ED while pending cardiology appointment and follow-up comprehensive echo.

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