CV Flashcards
Bainbridge reflex
Increased right atrial volume (as occurs post delivery due to uterine auto-transfusion engenders tachycardia through the Bainbridge reflex.
The Bezold-Jarisch reflex
engenders hypotension, bradycardia and coronary artery dilation in response to sympathetic overactivity causing contraction of an underfilled ventricle.
Cushing reflex
portends impending herniation in the context of elevated ICP, and is marked by hypertension and bradycardia.
baroreceptors vs chemoreceptors
- baroreceptor reflex which decreases heart rate.
- chemoreceptor reflex adjusts heart rate in response to oxygen, carbon dioxide and pH levels.
DOC to treat bradycardia in transplanted heart
Transplanted hearts have lost sympathetic and parasympathetic innervation. Sympathetic reinnervation has thought to possibly occur over time, but parasympathetic reinnervation has not been found to occur consistently. The denervated heart increases cardiac output with increased stroke volume followed by increased heart rate due to a normal response to circulating catecholamines. Resting heart rate is typically elevated in transplant patients due to lack of vagal tone. Drugs that block the parasympathetic system will not cause the desired effect due to denervation. Direct-acting agents such as isoproterenol or epinephrine should be used to increase the heart rate. Blood pressure may be increased with phenylephrine or norepinephrine.
Option A is incorrect because atropine acts via the autonomic system by blocking acetylcholine at the muscarinic receptors and will not reverse the bradycardia in a denervated heart.
Option B is incorrect because ephedrine works indirectly to release norepinephrine at sympathetic nerve endings and the effect is blunted in a cardiac transplant patient.
QRS crosswind to which cardiac cycle
Isovolemetric contraction
Ventricular ejection occur just after QRS
Phenylephrine Ca AS on p/v loop
Phenylephrine causes increase after load (increase pressure height on loop) but the LVEDV will also increase as blood returns increase (wide loop from increased volume)
AS will show high pressure with decreased SV and volume
An 80-year-old man presents to the cardiology suite for elective cardioversion. During synchronized cardioversion which of the following requires the least amount of energy for the initial shock?
A. Atrial fibrillation with biphasic shock
B. Atrial flutter with monophasic shock
C. PSVT with biphasic shock
D. PSVT with monophasic shock
“Atrial flutter with monophasic shock” is correct because it is typically quite amenable to cardioversion with low energy. A-fib is less so. PSVT is normally treated with vagal maneuvers and/or adenosine.
You’re examining a 62-year-old woman in the primary care clinic for progressive fatigue and confusion. Her past medical history is remarkable for renal cell carcinoma. Upon examination, she states that she has been having constipation, nausea, and vomiting. Her physical exam is remarkable for lessened bowel sounds. The lab tests reveal an adjusted serum calcium of 13.1 mg/dL and albumin of 3.7 g/dL. Which of the following would you expect to find on this patient’s ECG?
A. Widened QRS with a fusion of QRS-T and loss of ST segments
B. ST depression and flattening of T waves and a possible U-wave
C. Shortening of the QT interval with possible Osborn (J) waves
D. Increased PR and QTc, and a prolonged QRS
This case is describing a patient with severe (>12 mg/dL) hypercalcemia secondary to malignancy. The most common finding on an ECG associated with hypercalcemia is the shortening of the QT interval primarily secondary to a decrease in phase 2 of the ventricular action potential and a resultant decrease in the ST segment duration. Other findings may include Osborn waves and ventricular irritability leading to VF arrest. As such, option C is the correct choice.
Option A is listing the typical findings for a patient with hyperkalemia.
Option B, ST depression with possible U-waves is most commonly associated with hypokalemia.
Finally, Option D, increased PR and QTc, are the ECG findings of hypermagnesemia.
An 80-year-old man with moderate mitral regurgitation presents for prostatectomy. Hemodynamic goals intraoperatively include which of the following?
A. Normal sinus rhythm, avoid tachycardia
B. Normal to increased heart rate, decreased afterload
C. Normal to increased heart rate, decreased preload
D. Bradycardia
Mitral regurgitation (MR) can, over time, because left atrial dilation with subsequent atrial fibrillation, and increased left atrial pressure can lead to pulmonary hypertension. Hemodynamic goals for MR can be remembered by “Fast, Full, and Forward.” Heart rate should be normal to slightly increased (fast), have adequate intravascular volume (full), and systemic vascular resistance (SVR) should be reduced (forward). Increased SVR should be avoided as increased afterload will cause an increase in regurgitant flow through the mitral valve into the left atrium.
Option A is incorrect as relative tachycardia is suggested for management in MR. These goals are more suited for Aortic Stenosis (AS) or Mitral Stenosis (MS). Tachycardia is not tolerated in AS or MS patients because with tachycardia, there is a less diastolic filling time which leads to decreased cardiac output.
Option B is the correct answer.
Option C is incorrect. While normal to relative tachycardia is tolerable for patients with MR, preload should be maintained (not decreased) in MR along with AS, MS, and aortic regurgitation (AR).
Option D is incorrect. Bradycardia is not optimal management for mitral regurgitation.
