Special pathology - cardiology Flashcards
veterinary cardiology focuses on?
small animal medicine
it just isn’t as applicable to large animal medicine.
The heart is
a muscular four-chambered pump that simultaneously supplies blood to the pulmonary and systemic circulatory beds.
Vascular system is subdivided: (4)
arterial
capillary
venous
lymphatic segments
Heart lies within a fibroelastic sac =
pericardium
wall of the heart is composed of three layers:
epicardium
myocardium
endocardium
heart contains in order of blood flow four major blood vessels:
vena cava,
pulmonary artery
pulmonary vein
aorta
name the heart Valves:
tricuspid / right atrioventricular
pulmonic semilunar
mitral / bicuspid / left atrioventricular
aortic semilunar
Stroke volume or systolic volume (SV) is defined as
The amount of blood ejected per beat by the left ventricle into the aorta
(or from the right ventricle into the pulmonary artery).
Cattle 0.5 – 0.6 l (at rest)
Horse 0.8 – 0.9 l
Cardiac output (CO) is defined as
cardiac minute volume so the total volume of blood pumped by the heart per minute (denoted with symbol ‘Q’).
Cattle 30 – 35 l
Horse 20 – 30 l
Cardiac output can be increased by how much
5 – 6 times.
The maximum and minimum stroke volumes characterise accommodation dynamics, or the extent of adaptation.
In the case of short-term physical loads, what type of regulation of cardiac function occurs?
neural regulation (via the parasympathetic and
sympathetic nervous systems), and endocrine regulation
Reflex regulation of cardiac function occurs via
the cardiovascular centre of medulla oblongata (myelencephalon).
Mechanical pumping of the heart must be preceded by
an electrophysiologic process that triggers a coordinated
chronologic sequence of electrical events that result in muscle contractions.
This electrophysiologic process is made possible by a network of special conducting fibers that are collectively referred to as the cardiac conduction system.
the two phases of a cardiac contraction are
-sequential contraction (systole)
-relaxation (diastole)
Nerve supply to the heart: (3-4)
is autonomic and includes
-sympathetic-
-parasympathetic &
-nonadrenergic noncholinergic innervation
What provides the force of cardiac contraction?
What controls the flow and volume of the heart?
Cardiac myocytes provide the force of contraction;
the conduction system and the nervous system control the flow and volume.
Angiocardiography
method of following the passage of blood through the heart and great vessels by means of the intravenous injection of a radiopaque fluid, whose passage is followed by serialized X-ray pictures.
purpose of Cardiac catheterization
may be performed to diagnose or evaluate: Causes of congestive heart failure or cardiomyopathy.
used to examine your heart valves or take samples of blood or heart muscle.
may also be done to treat some types of heart conditions
Cardiac myocardial damage can be detected by increased activity of serum enzymes and isoenzymes such as: (5)
creatine kinase (CK)
lactate dehydrogenase (LDH)
troponin T (TnT)
troponin I (TnI)
aspartate aminotransferase (AST)
increased plasma concentrations of what may indicate
cardiac disease
besides serum enzymes, the 2 hormones:
plasma natriuretic peptides (A type [atrial] ANP and B type [brain BNP)
These hormones are synthesized and released by cardiac muscle cells in increased amounts during cardiac dysfunction.
Heart failure is
a progressive clinical syndrome in which impaired pumping decreases ventricular ejection and impedes venous return.
In heart failure, the heart fails either by
decreased blood pumping into the aorta and/or pulmonary artery to maintain arterial pressure (low-output heart failure)
or by an inability to adequately empty the venous reservoirs (congestive heart failure).
low-output heart failure broadly involves
decreased blood pumping into the aorta and/or pulmonary artery to maintain arterial pressure
congestive heart failure broadly involves
an inability to adequately empty the venous reservoirs
Anamnestic signs of low cardiac output include: (4)
depression
lethargy
syncope
hypotension
Anamnestic signs of congestive heart failure include what (3) in addition to the same signs that appear with low-output?
ascites,
pleural effusion,
pulmonary edema
Congestive heart failure can be
right-sided, left-sided, or bilateral
and can occur with cardiac dilation and/or hypertrophy.
Right-sided congestive heart failure is associated with signs of
congestion in the systemic circulation (i.e., ascites and peripheral edema)
left-sided congestive heart failure causes signs of
congestion in the pulmonary circulation (i.e., pulmonary edema and dyspnea)
In small animals, pleural effusion is usually associated with
bilateral congestive heart failure.
Heart failure may result from: (3)
an inability of the heart to eject blood adequately,
from inadequate ventricular filling,
or both.
The resultant reduction in stroke volume (SV) leads to a decrease in cardiac output (CO) and a decrease in arterial blood pressure.
(systolic failure) can be described as
an inability of the heart to eject blood adequately
(diastolic failure) can be described as
inadequate ventricular filling
reduction in stroke volume (SV) leads to
a decrease in cardiac output (CO) and a decrease in arterial blood pressure.
Most Common Cardiac Diseases of Horses (4)
Fibrinous pericarditis
Toxic cardiomyopathy (ionophores, white snakeroot)
Endocardial fibrosis and calcification
Endocarditis
Most Common Cardiac Diseases of pigs (3)
Mulberry heart disease (vitamin E–selenium deficiency)
Pericarditis
Endocarditis
Most Common Cardiac Diseases of Ruminants (Cattle, Sheep, and Goats) (6)
White muscle disease (vitamin E–selenium deficiency)
Cardiotoxicity (ionophores, gossypol, Cassia occidentalis, Karwinskia humboldtiana)
Brisket disease (high-altitude disease)
Pericarditis
Endocarditis
Malignant lymphoma
Most Common Cardiac Diseases in Dogs (6)
myxomatous valvular degeneration (valvular endocardiosis)
congenital heart disease
dilated cardiomyopathy
hemorrhagic pericardial effusion
cardiac neoplasia
dirofilariasis
Most Common Cardiac Diseases in cats (4)
hypertrophic cardiomyopathy
dilated cardiomyopathy
hyperthyroidism-associated hypertrophy
congenital heart disease
Myocarditis is generally the result of
infections spread hematogenously to the myocardium and occurs in various systemic diseases.
Types of inflammation provoked by infectious agents that produce myocarditis include: (5)
suppurative
necrotizing
hemorrhagic
lymphocytic
eosinophilic
Suppurative myocarditis results from
localization of pyogenic bacteria in the myocardium that are trapped in thromboemboli most commonly originating from vegetative valvular endocarditis on the mitral and aortic valces.
Hypertrophy and Atrophy Cardiomyopathies are divided into five morphologic types:
hypertrophic
dilated (congestive)
restrictive
arrhythmogenic right ventricular
unclassified cardiomyopathies
Secondary cardiomyopathies are
(also termed specific heart muscle diseases)
are generalized myocardial diseases of known cause.
Cardiomyopathy is defined as
as a primary disease of the myocardium.
Most of the cardiomyopathies of animals are
idiopathic diseases that are not the result of any systemic or other primary cardiac disease.
The cause has been identified in some cases as a genetic mutation and in others as an inherited trait.
In animals (primarily dogs and cats), cardiomyopathies are classified as (4)
dilated cardiomyopathy,
hypertrophic cardiomyopathy,
arrhythmogenic right ventricular cardiomyopathy, and
restrictive cardiomyopathy.
In cats, if a specific cardiomyopathy cannot be identified,
the disease is classified as
cardiomyopathy, nonspecific phenotype.
Dilated cardiomyopathy (DCM) is characterized by
the progressive loss of myocyte number and/or function, along with a decrease in cardiac contractility.
DCM is most prevalent in dogs, it typically occurs in middle-aged to older male dogs.
Causes of DCM include chemical (eg, doxorubicin), viral (eg, parvovirus), nutritional (taurine deficiency), genetic (in Doberman Pinschers and Boxers), or idiopathic.
Myocardial necrosis and mineralization can result from a number of causes: (6)
-nutritional deficiencies
-chemical and plant toxins
-ischemia
-metabolic disorders
-heritable diseases
-physical injuries
What is Myxomatous Valvular Degeneration (Valvular Endocardiosis)?
non-inflammatory progressive disarray of the valve structure caused by a defect in the mechanical integrity of the leaflet due to the altered synthesis and/or remodeling by type VI collagen. = becomes floppy and no longer does its job right
Degenerative changes in the valves are frequently seen in older dogs.
Pericarditis is
Inflammation of the pericardium frequently seen with bacterial septicemias and typically results in fibrinous pericarditis.
pericarditis grossly
both the visceral and parietal pericardial surfaces are covered by variable amounts of yellow fibrin deposits, which can result in adherence between the parietal and visceral layers.
Pericardial Dilatation is
when The pericardium responds to excess fluid in the pericardial space by dilation.
outcome requires adequate time to allow adjustments in size
In hemopericardium,
blood rapidly fills the pericardial cavity and death often occurs
unexpectedly from cardiac tamponade
cardiac tamponade is
a condition with compression of the heart caused by blood accumulation leading to reduced cardiac output.
Hydropericardium is
the accumulation of clear, light yellow, watery, serous fluid (i.e., transudate) in the pericardial sac.
Most Common Diseases with Thrombosis and/or Embolism in Animals (up to 8)
Pulmonary thromboembolism
Aortic thromboembolism with cardiomyopathy: “Saddle” thrombi.
Aortoiliac thrombosis in horses
Verminous arteritis in horses: Strongylus vulgaris
Septic embolism from lesions of vegetative endocarditis
Fibrocartilaginous emboli: dogs
Conditions accompanied by DIC
Thrombosis of caudal vena cava: Cattle
the 3 predisposing conditions that may result in thrombi
altered blood flow, hypercoagulability, endothelial damage
most common site of Arterial Thromboembolism and Thrombosis in dogss
Aortoiliac thromboembolism
Dirofilariasis (immitis)
(heartworm disease) an infection by parasites of the genus Dirofilaria. It is transmitted through a mosquito bite; its main hosts include dogs.
the parasites accumulate in the pulmonary arteries and as the numbers increase, they are present in the right ventricle, then in the right atrium, and finally may occupy the vena cavae.
Pulmonary hypertension results from vascular blockage and pulmonary vascular lesions produced by the parasites, and right ventricular hypertrophy follows.
Right-sided heart failure may eventually develop.
