Chapter 11 Part II: Cardiovascular System Flashcards
Heart: Arrhythmias / dysrhythmias
• Heart block (atrioventricular block)
• Flutter
• Fibrillation
Examples of cardiac arrhythmias: Bradycardia (slow HR) and heart block (atrioventricular / AV block)
Improper conduction of impulses from SA node through AV node to AV bundle?
- SA node damage with weak impulses?? Can result in bradycardia with “skipped” heartbeats. If no impulse reaches AV node, then we have a complete “AV block” that can also result in Rt and Lt bundle branch block (RBBB, LBBB).
- Implantation of cardiac pacemaker.
Examples of cardiac arrhythmias: Flutter
Rapid but regular contraction, usually in the atria.
- May reach 300 BPM
- Tx includes meds, cardioversion
Examples of cardiac arrhythmias: Fibrillation
Very rapid, random, inefficient and irregular contractions of the heart (350 BPM or more).
- Atrial fibrillation (AF, “A fib”): most common arrhythmia, 5-10% in 70-80 YO or >15% in 80 YO’s.
- Pt experiences palpitation (uncomfortable sensations in the chest) that can be paroxysmal or permanent.
Examples of cardiac arrhythmias: Ventricular fibrillation
- Electrical impulses move randomly throughout the ventricles.
- Can be life-threatening and result in sudden cardiac death or cardiac arrest.
- Treat with meds (digoxin, beta-blockers and calcium channel blockers) or if urgent, defibrillation.
Examples of cardiac arrhythmias: Ventricular fibrillation
Implantable cardioverter-defibrillator (ICD)
Implanted inside the chest to sense arrhythmias and terminate them with a shock.
Ventricular Tachycardia
Ventricular rate may be as high as 250 beats per minute. The rhythm is regular, but the atria are not contributing to ventricular filling and blood output is poor.
Ventricular Fibrillation
Notice the abnormal, irregular waves. Ventricles in fibrillation cannot pump blood effectively. Circulation stops and sudden cardiac death follows if fibrillation is not reversed.
Congenital heart disease:
- Coarctation of the aorta (CoA)
- Patent ductus arteriosus (PDA)
- Septal defects (ASD and VSD)
- Tetralogy of Fallot
Contraction of the aorta (CoA)
Localized narrowing of the aorta reduces the supply of blood to the lower part of the body.
Patent ductus arteriosus (PDA)
The ductus arteriosus fails to close after birth, and blood from the aorta flows through it into the pulmonary artery.
Ductus Arteriosus ————>
Ligamentum Arteriosum
Congenital
Born with it.
Septal defect
• Small holes in the wall b/w the atria (atrial septal defect, ASD) or the ventricles (ventricular septal defect, VSD)
- If the holes do not close spontaneously, will require an open heart surgery with a heart-lung machine.
Ventricular septal defect
A hole in the ventricular septum causes blood to flow from the left ventricle to the right and into the lungs via the pulmonary artery.
Congestive heart disease (CHF)
The heart is unable to pump the required amount of blood.
• In the U.S., primarily the result of high blood pressure and coronary artery disease.
• Symptoms include pulmonary edema (fluid accumulation in the lungs), swelling/edema in the legs, feet and ankles.
• Tx includes: meds including diuretics to promote fluid loss, lifestyle modification (less Na intake, diet control) or surgery if others fail.
Pulmonary circulation
- Blood picks up oxygen; blood loses carbon dioxide.
- Blood flow from the heart to lung capillaries and back to the heart.
Systemic circulation
- Blood loses oxygen to cells; blood picks up carbon dioxide.
- Blood flow from the heart to tissue capillaries and back to the heart.