UNIT 3 CV 🫀 Flashcards
Define chronotropy
HR
Chronotropy refers to the heart rate and how it is influenced by various factors.
Define inotropy
Strength of contraction (contractility)
Inotropy describes the force of heart muscle contraction.
Define dromotropy
Conduction velocity (how fast the AP travels per time)
Dromotropy relates to the speed at which electrical impulses propagate through the heart.
Define lusitropy
Rate of myocardial relaxation (during diastole)
Lusitropy indicates how well the heart muscle relaxes after contraction.
What is the function of the sodium-potassium pump?
Maintains cell resting potential, removes Na+, returns K+
The sodium-potassium pump is crucial for maintaining the negative resting potential of cells, particularly in cardiac myocytes.
List the 5 phases of ventricular AP
Phase 0: depolarization (Na influx)
Phase 1: initial repolarization (K efflux, Cl influx)
Phase 2: plateau (Ca influx)
Phase 3: repolarization (K efflux)
Phase 4: resting membrane potential restoration
These phases describe the electrical activity during a cardiac action potential.
List the 3 phases of SA node AP
Phase 4: spontaneous depolarization (leaky to Na)
Phase 0: depolarization (Ca influx)
Phase 3: repolarization (K efflux)
The SA node’s action potential is crucial for initiating the heartbeat.
What determines the intrinsic HR?
Rate of spontaneous phase 4 depolarization in the SA node
This rate can be influenced by various physiological factors.
What is the calculation for MAP?
MAP = (1/3 x SBP) + (2/3 x DBP)
MAP is a critical parameter for assessing perfusion pressure.
What is the formula for SVR?
([MAP – CVP) / CO] x 80
SVR indicates systemic vascular resistance.
What is the formula for pulmonary vascular resistance?
[(MPAP – PAOP) / CO] x 80
This formula helps assess the resistance in the pulmonary circulation.
Describe the Frank-Starling relationship
Relationship between ventricular volume (preload) and output (CO)
It states that increased preload leads to increased cardiac output until a certain point.
What factors affect myocardial contractility (inotropy)?
Chemicals affecting contractility, particularly calcium
Contractility can be altered by various substances that influence calcium levels.
What is afterload?
The force the ventricle must overcome to eject its stroke volume
Afterload is an important determinant of cardiac performance.
What law describes ventricular afterload?
Law of LaPlace
This law relates wall stress to intraventricular pressure, radius, and wall thickness.
List 2 conditions that set afterload proximal to the systemic circulation
- Aortic stenosis
- Coarctation of the aorta
These conditions increase the workload on the heart.
What are the 6 stages of the cardiac cycle?
- Atrial systole
- Isovolumetric contraction
- Ventricular systole
- Isovolumetric relaxation
- Ventricular filling
- Atrial diastole
These stages describe the sequence of events during one heartbeat.
How do you calculate ejection fraction?
EF = (SV / EDV) x 100
Ejection fraction measures the percentage of blood ejected from the heart during systole.
What is the best TEE view for diagnosing myocardial ischemia?
Midpapillary muscle level in short axis
This view provides optimal visualization of the left ventricle.
What is the equation for coronary perfusion pressure?
Coronary PP = aortic DBP – LVEDP
This equation is essential for understanding blood supply to the myocardium.
Which region of the heart is most susceptible to myocardial ischemia?
LV subendocardium
This area is particularly vulnerable during diastole due to its blood supply dynamics.
What factors affect myocardial oxygen supply and demand?
Discuss the nitric oxide pathway of vasodilation
NO synthase catalyzes L-arginine to NO, which activates guanylate cyclase, increasing cGMP and causing smooth muscle relaxation
This pathway is crucial for vascular regulation.
What are the two primary ways a heart valve can fail?
- Stenosis
- Regurgitation
These failures can lead to significant hemodynamic consequences.
How does the heart compensate for pressure overload?
Concentric hypertrophy
This adaptation increases wall thickness to manage increased pressure.
How does the heart compensate for volume overload?
Eccentric hypertrophy
This adaptation increases chamber size to accommodate extra volume.
What is the most common dysrhythmia associated with mitral stenosis?
Atrial fibrillation
This arrhythmia is often a consequence of atrial enlargement.
List 6 risk factors for perioperative cardiac morbidity and mortality for non-cardiac surgery
- High-risk surgery
- History of ischemic heart disease
- History of congestive heart failure
- History of cerebrovascular accident
- Diabetes mellitus
- Serum creatinine > 2 mg/dL
These factors are critical for assessing surgical risk.
What is the risk of perioperative MI in the patient with previous MI?
Gen pop: 0.3%, >6mo: 6%, 3-6mo: 15%, <3mo: 30%
Timing of previous myocardial infarction significantly influences risk.
Categorize high, medium, and low-risk surgical procedures according to cardiac risk
High (>5%): emergency surgeries, open aortic surgeries, peripheral vascular surgeries
Medium (1-5%): carotid endarterectomy, head and neck surgeries, intrathoracic surgeries
Low (<1%): endoscopic procedures, cataract surgeries, superficial surgeries
Understanding the risk categories helps in preoperative planning.
How do you interpret cardiac enzymes in the patient with suspected ischemic event?
Infarcted myocardium releases CK-MB, troponin I, troponin T; troponins are more sensitive for diagnosing MI
Timing and context of enzyme elevation are crucial for diagnosis.
How do you treat intraoperative myocardial ischemia?
Make the heart slower, smaller, and better perfused
This approach improves myocardial oxygen supply.
What factors reduce ventricular compliance?
- Age > 60 years
- Ischemia
- Pressure overload hypertrophy
- Hypertrophic obstructive cardiomyopathy
- Pericardial pressure
These factors impact the heart’s ability to fill properly.
What is the difference between HFrEF and HFpEF heart failure?
HFrEF: vent doesn’t empty well, ↓ EF with ↑ EDV
HFpEF: vent doesn’t fill properly, heart can’t relax, ↓ vent compliance
Understanding these differences is essential for management.
What is the Modified NY Association Functional Classification of HF?
Class 1: asymptomatic, Class 2: symptomatic with moderate activity, Class 3: symptomatic with mild activity, Class 4: symptomatic at rest
This classification helps assess heart failure severity.
List 6 complications of hypertension
- LVH
- Ischemic heart disease
- CHF
- Arterial aneurysm
- Stroke
- End-stage renal disease
Hypertension has widespread effects on various organs.
How does hypertension contribute to CHF?
How does hypertension affect cerebral autoregulation?
Chronic HTN shifts curve to the right; helps brain tolerate higher BPs but not lower BPs
This shift can lead to increased risk of complications during hypotensive episodes.
What’s the difference between primary and secondary hypertension?
Primary (essential): no identifiable cause (95% of cases)
Secondary: due to other pathology (5% of cases)
Distinguishing between these types is important for treatment.
List 7 causes of secondary hypertension
- Coarctation of the aorta
- Renovascular disease
- Hyperadrenocorticism
- Hyperaldosteronism
- Pheochromocytoma
- Pregnancy-induced hypertension
Identifying secondary causes is crucial for effective management.
What are the two major classes of CCBs?
Describe the pathophysiology of constrictive pericarditis
Fibrosis thickens pericardium, limiting diastolic filling and increasing ventricular pressure
This condition can lead to heart failure due to impaired filling.
Describe the anesthetic management of constrictive pericarditis
CO dependent on HR, avoid bradycardia, preserve HR and contractility
Anesthetic approach must consider hemodynamic stability.
Describe the pathophysiology of pericardial tamponade
Fluid in pericardium increases pressure, limiting filling and pumping ability
This condition leads to rising CVP and equalization of cardiac diastolic pressures.
What is Kussmaul’s sign?
JVD and ↑ CVP, most pronounced during inspiration
This sign indicates impaired RV filling.
List 2 conditions commonly associated with Kussmaul’s sign
- Constrictive pericarditis
- Pericardial tamponade
Kussmaul’s sign can occur with any condition limiting RV filling.
What is pulsus paradoxus?
Exaggerated ↓ in SBP during inspiration (>10 mmHg)
This phenomenon suggests impaired diastolic filling.
List 2 conditions commonly associated with pulsus paradoxus
- Constrictive pericarditis
- Pericardial tamponade
Both conditions can lead to this clinical finding.
What is Beck’s Triad?
HoTN, JVD, muffled heart tones
This triad is indicative of acute cardiac tamponade.
What is the best anesthetic technique for the patient with acute pericardial tamponade undergoing pericardiocentesis?
Local anesthesia preferred; if GETA, preserve myocardial function
Minimizing hemodynamic impact is crucial.
List 7 patient factors that warrant antibiotic prophylaxis against infective endocarditis
- Previous infective endocarditis
- Prosthetic heart valve
- Unrepaired cyanotic congenital heart disease
- Repaired congenital heart defect if <6mo old
- Repaired CHD with residual defects
- Heart transplant with valvuloplasty
These factors increase the risk of developing endocarditis.
List 3 surgical procedures that warrant antibiotic prophylaxis against infective endocarditis
- Dental procedures involving gingival manipulation
- Respiratory procedures that perforate mucosal lining
- Biopsy of infective lesions on skin or muscle
These procedures pose a risk of bacteremia.
What are the 3 key determinants of flow through the LVOT?
- Systolic LV volume
- Force of LV contraction
- Transmural pressure gradient
These determinants are critical for understanding cardiac output.
What factors reduce CO in the patient with obstructive hypertrophic cardiomyopathy?
Anything that narrows the LVOT
Obstruction can significantly limit cardiac output.
How long should elective surgery be delayed after percutaneous coronary intervention?
What is the difference between alpha-stat and pH-stat blood gas measurement during CPB?
Alpha-stat does not correct for temp; pH-stat corrects for temp aiming to keep constant pH
This difference impacts outcomes in adults and pediatrics.
Why is a left ventricular vent used during CABG surgery?
Removes blood from the LV
This vent helps prevent distention and improves surgical conditions.
How does the IABP function throughout the cardiac cycle?
What does the Alpha-stat management technique NOT correct for?
Temperature
Alpha-stat maintains intracellular charge neutrality across all temperatures and is associated with better outcomes in adults.
What is the main goal of the pH-stat management technique?
Keep a constant pH across all temperatures
pH-stat corrects for patient temperature and is associated with better outcomes in pediatric patients.
What is the purpose of using a left ventricular vent during CABG surgery?
Removes blood from the left ventricle
The blood comes from Thebesian veins and bronchial circulation (anatomical shunt).
How does the IABP inflate during the cardiac cycle?
Inflates during diastole
This inflation helps perfuse the coronaries and correlates with the dicrotic notch on the aortic pressure wave.
What happens during systole when the IABP deflates?
Decreases afterload and increases cardiac output
This deflation correlates with the R wave on ECG.
What are the effects of IABP on myocardial oxygen supply and demand?
Increases myocardial O2 supply while decreasing myocardial O2 demand
This is beneficial for the patient.
List four contraindications for the IABP.
- Severe aortic insufficiency
- Descending aortic disease
- Severe peripheral vascular disease (PVD)
- Sepsis
What classification system describes aortic aneurysms?
Crawford classification system
This system categorizes aortic aneurysms based on their anatomical features.
What are the two classification systems for aortic dissection?
- DeBakey classification
- Stanford classification
Which law describes the relationship between aortic diameter and risk of aortic rupture in AAA?
Law of Laplace
This law states that wall tension equals transmural pressure times vessel radius.
What is the threshold diameter for increased mortality risk in AAA?
> 5.5 cm
Surgical correction is recommended if the diameter increases by > 0.6-0.8 cm in a year.
How does aortic cross-clamping contribute to the risk of anterior spinal artery syndrome?
X-clamping above the artery of Adamkiewicz may cause ischemia to the lower portion of the anterior spinal cord
This can lead to ASAS or Beck’s syndrome.
What are the symptoms of anterior spinal artery syndrome (ASAS)?
- Flaccid paralysis of lower extremities
- Bowel and bladder dysfunction
- Loss of temperature and pain sensation in lower extremities with preserved touch and proprioception
What is amaurosis fugax?
Blindness in one eye
It is a sign of impending stroke caused by an embolus traveling from the internal carotid to the ophthalmic artery.
What regional technique can be used for a carotid endarterectomy (CEA)?
Cervical plexus block or local infiltration
The levels that must be blocked are C2-C4.
What reflex can be activated during CEA or following carotid balloon inflation?
Baroreceptor reflex
This is also known as the pressure reflex.
What is the best treatment for a patient who develops a hematoma post-right CEA with complete airway obstruction?
Cricothyroidotomy
This should be performed if the surgeon is not available for an emergent decompression.
