Classes of drug used to treat pulmonary hypertension?
1. CCB (not verapamil - too much negative inotropy)
2. Prostacyclin analogs (epoprostenol - IV, iloprost - aerosol)
3. PDE-inhibitors (sildenafil)
4. Endothelin receptor antagonists (bosentan - oral)
How does hypoxia affect pulmonary vascular resistance? Hypercarbia? Acidosis? Hypothermia?
They all increase PVR and RV afterload
How does nitrous oxide affect the pulmonary vasculature?
Vasoconstricts the pulmonary vasculature
What pressors should you avoid in patients with pulmonary hypertension?
Alpha agonists (increases PVR)
What prolongs the plateau phase of the myocardial action potential?
Calcium channel opening (Ca++ in, K+ out)
How does the SA node depolarize itself?
Slow leak of Ca++ into the cell that triggers an action potential
How do volatile anesthetics affect the SA and AV node?
Depresses both nodes (SA node more so than AV node)
How do opioids affect the SA and AV nodes?
Increases AV nodal conduction time but less effect on SA node
What nerves (SNS and PSNS) innervates the SA node?
The right vagus and sympathetic chain (T1-T4)
What nerve innervates the AV node?
Left vagus nerve
What is the difference between SVR and afterload?
Afterload: arterial impedance to ejection (vaso-elastic properties of the aorta, arteriolar tone, density/viscosity of blood) SVR: only measure arteriolar tone
What is LVEDP (increased or decreased) for a patient with diastolic dysfunction?
Increased (needed for filling)
What supplies the posterior mitral papillary muscle?
Posterior descending artery
What supplies the anterior mitral papillary muscle?
Left circumflex and LAD
When does the right ventricle get perfused? The left?
Right: Diastole and systole Left: Only during diastole
Major risk factors for cardiovascular risk?
Acute/recent MI (within 6 months), unstable angina, high grade AV block symptomatic ventricular arrhythmias, SVTs with uncontrolled ventricular rate, severe valvular disease
Intermediate risk factors for cardiovascular risk?
DM, MI >6 months ago, compensated CHF, renal insufficiency, mild angina
What is the most sensitive and specific monitor for intraop MI?
TEE (wall motion abnormalities)
What are the BP and HR goals for a patient with severe mitral regurgitation?
Decreased afterload (forward flow) and moderately high HR (80-100)
What are the findings for Tetralogy of Fallot?
PROV P: Pulmonary stenosis R: RV hypertrophy O: Overriding aorta V: VSD
Describes the cardiopulmonary bypass circuit.
RA -> venous reservoir -> oxygenator and heat exchanger -> adds/removes CO2 -> main pump -> arterial filter -> aorta
What is pH-stat?
pH is kept static (if patient is cold, the temperature corrected ABG should have a pH of 7.4); hypothermia increases CO2 solubility (decreased pCO2), so CO2 has to be added to the patient's blood to keep the pH static. When the blood is warmed in the analyzer to 37C, the added CO2 causes a respiratory acidosis picture.
What is alpha-stat?
No CO2 is added to the circuit and at 37C, the pH is 7.4. When the patient is cooled and CO2 solubility increases (decreased pCO2), there is an apparent respiratory alkalosis.
Neurologic outcomes are worse with alpha stat or pH stat?
What is a common complication with TAA repairs?
Lower extremity paralysis (10%) due to the anterior spinal artery (Artery of Adamkiewicz) which can be cut off feeding the lower thoracic and upper lumbar spinal cord; anterior spinal cord = motor, pain/temp, light touch (proprioception, deep touch, and vibratory senses often spared - dorsal/posterior spinal cord)
Pulsus paradoxus + muffled heart sounds + electrical alternans and JVD?
Patient with hypertension and aortic dissection needs what initial treatment?
Beta-blocker drip (reduce shear forces by decreasing HR and contractility)
When do you hear an S3 heart sound and why?
Early diastole just after S2 As atrial blood reverberates against poorly functioning ventricular walls that relax slowly, you get a knocking sound
What happens to preload (RV and LV), afterload, blood pressure during spontaneous inspiration?
Intrathoracic and pleural pressures are negative -> increased RV preload
Increased pulmonary venous capacitance -> decreased LV preload
Slightly increased afterload -> slight decrease in BP (from decreased preload and increased afterload)
Why does your heart rate increase slightly with inspiration?
Inhibition of vagal tone (respiratory sinus arrhythmia)