3.3.2. Cardiac Pathology Part 3: Missing Information Flashcards
What in general causes cardiac hypertophy?
Sustained increased in mechanical work due to pressure or volume overload (e.g. those mediated through the activation of B-adrenergic receptors) causes myocytes to increase in size; cumulatively, this increases the size and weight of the heart
What occurs with pressure-overload hypertrophy?
- Due to hypertension or aortic stenosis
- New sarcomeres are predominantly assembled in parallel
- Causes concentric increase in wall thickness
What occurs with volume overload hypertrophy?
- Characterized by new sarcomeres being assembled in series within existing sarcomeres, leading primarily to ventricular dilation
- Wall thickness may increase, stay the same, or decrease
- Heart weight is a better measure of hypertrophy in dilated hearts
Describe how nutrient and blood supply changes to a heart that has undergone hypertrophy
Myocyte hypertrophy is not accompanied by a proportional increase in capillary numbers; supply of oxygen and nutrients to hypertrophied hearts is more tenuous than the normal heart, but the oxygen consumption of the heart is elevated due to the increased workload
Therefore, the hypertrophied heart is vulnerable to ischemia-related decompensation
Hypertrophy is often accompanied by deposition of ____ ____.
Hypertrophy is often accompanied by deposition of fibrous tissue
The molecular and cellular changes in hypertrophied hearts that initially mediate enhanced function may themselves contribute to the development of heart failure in four ways:
Abnormal myocardial metabolism
Alterations of intracellular handling of calcium ions
Myocyte apoptosis
Reprogramming of gene expression
Distinguish between forward and backward pump failure seen in CHF
CHF is characterized by variable degrees of cardiac output and tissue perfusion (sometimes called pump forward failure), as well as pooling of blood in the venous capacitance system (backward failure); the latter may cause pulmonary edema, peripheral edema, or both
When we see splinter hemorrhages, what should we think of?
Endocarditis
Mildest chest x ray finding suggesting pulmonary congestion
Perivascular and interstitial edema, particularly in the interlobular septa, responsible for the characteristic Kerly B and C lines noted on chest X-ray study in CHF
Discuss how heart failure cells come around
Accumulation of edema fluid in the alveolar spaces. Some red cells and plasma proteins extravasate into the edema fluid within the alveolar spaces, where they are phagocytosed and digested by macrophages, which store the iron recovered from hemoglobin in the form of hemosiderin. These hemosiderin-laden macrophages (aka heart failure cells) are telltale signs of previous episodes of pulmonary edema. Pleural effusions arise from elevated pleural capillary pressure
In right sided heart failure, we have huge effects in the liver and portal system. One symptom is the “nutmeg” liver. What causes this?
The liver is usually increased in size and weight (congestive hepatomegaly) due to prominent passive congestion, greatest around the central veins. Grossly, this is reflected as congested red-brown pericentral zones, with relatively normal-colored tan periportal regions, producing the characteristic nutmeg liver appearance
____ ____ ____ are the major known causes of Congenital Heart Disease.
Sporadic genetic abnormalities are the major known causes of CHD.
The most common genetic cause of CHD is trisomy 21
most often associated with structures derived from the ___ ___ ___.
The most common genetic cause of CHD is trisomy 21
most often associated with structures derived from the second heart field
Discuss the formation and purpose of the septum primum
Septum Primum
crescent-shaped membranous ingrowth that sits posteriorly between the R & L atria and partially separates them; the ostium primum is the remaining anterior opening that allows movement of blood from the R to L atrium during fetal development
The septum primum completely obliterates the ostium primum before growing, developing a second posterior opening: ostium secundum
Discuss the formation and purpose of the septum secundum
Septum secundum: subsequent membranous ingrowth located to the R and ant. of the septum primum
as the septum secundum grows, it leaves a small opening– foramen ovale– that is continuous with the ostium secundum; these structures permit continued L → R shunting of blood during intrauterine development
SS continues to enlarge until it forms a flap of tissue that covers the foramen ovale on its L side
Describe the two different types of ASD in regards to prevalence and location
classified according to their location
Secundum ASD (90% of all ASD)
- deficient septum secundum formation near center of atrial septum
Primum anomalies (5% ASD)
- occur adjacent to AV valves
- often associated with AV valve anomalies and VSD
Sinus Venosus defects (5%)
- located near the entrance of the SVC
- can be associated with anomalous pulmonary venous return to the right atrium
When do Atrial Septal Defect patients usually present?
Usually do not become symptomatic until ~30 y/o
In Atrial Septal Defect patients, does pulmonary blood flow increase or decrease and by how much?
pulmonary blood flow 2-8X normal
We see an interesting shunt pattern in Eisenmerger Syndrome. What is it?
Eventually the L→ R shunt becomes a R→ L shunt b/c pulmonary vascular resistance approaches systemic levels introducing poorly oxygenated blood into systemic circulation
In Ventricular septal defects, where do we see the issues in the IV septum?
~90% are membranous (occur in the region of the membranous interventricular septum
~10% are infundibular (occur below the pulmonary valve or within the muscular septum)
Describe the normal pattern and use of the Ductus Arteriosus
During intrauterine life, the DA permits blood flow from the pulmonary artery to the aorta, bypassing the lungs.
Shortly after birth, the DA should constrict and become functionally closed (becoming the ligamentum arteriosum)
PDA produces this kind of murmur
PDA produces a characteristic continuous harsh “machinery-like” murmur
3 y/o male with cyanosis (progressive since 6 months of age)
clubbing of fingers and toes
gray sclerae, dusky blue skin surfaces
Auscultation: pulmonary systolic ejection murmur
Thinking what?
Tetralogy of Fallot
5 T’s of Cyanotic Congenital Heart Malformations
- Tetralogy of Fallot
- Transposition of the Great Vessels
- Tricuspid Atresia
- Truncus Arteriosus
- TAPVR: total anomalous pulmonary venous return
