DVM Heart Disease An introduction to problems that can occur in the heart Partnership for Environmental Education and Rural Health Texas A&M University http://peer.tamu.edu
Heart Failure: The people costs (U.S.) Myth: Only men suffer from Heart Failure. Fact: Over 50% of sufferers are women. How many people are affected with Heart Failure? 5 million (2x a decade ago) How many people die each year of Heart Failure? 287,000
Heart Failure: The dollar costs (U.S.) How much money is spent on health care of patients with Heart Failure? • direct costs 29.6 billion • lost productivity 37.2 billion
Basic Anatomy • Arteries – Carry blood away from the heart • Veins – Carry blood to the heart • Capillaries – Site of gas exchange
The Heart as a Pump • The heart works as a pump, forcing blood forward into the arteries. • Blood returns to the heart in veins. Veins have valves. • Question: What is the function of the valves? Hint: in the diagram, look at the direction of blood flow and how the valves close
3-D Graphic of a Beating Dog Heart Click to View Courtesy of Odyssey Veterinary Software http://www.diawebster.com/ This is a spectacular video. You must have Windows Media Player and linked file must be in the same folder as this PowerPoint. It may not run on all PCs.
Blood Oxygenation Right side pumps venous blood into lungs, which drains into left side of heart for pumping oxygenated blood to the brain and body.
Heart Rate • A slower rate tends to move more blood per beat. Why? • Fast rates tends to move more total blood. Why? • But very fast rates are not efficient and may even be dangerous. Why?
Review Questions • Diagram the flow of blood throughout the body, indicating where in the circuit the blood is most oxygenated. • Why do veins have valves? • How does lung structure promote oxygenation?
Heart Attacks Cause: heart arteries get filled with deposits (“plaques”) that promote clots that block the artery. See artery cross section below: narrowed opening for blood flow plaque
Coronary Arteries and Veins The heart needs blood and oxygen too!! When one of these arteries gets blocked, a heart attack can occur
Causes of Heart Attacks • Genetics: it can run in families • Diet: too much fat and cholesterol • Not enough vigorous exercise
What is Congestive Heart Failure (CHF)? The inability of the heart to pump enough blood to the rest of the body. Why do you suppose it is called CONGESTIVE heart failure?
CHF in Dogs • Causes: • Birth (congenital) defects of the heart • Degeneration of the heart valves • Heart muscle disease (cardiomyopathy) • Heartworm disease • Diseases of the pericardium (the lining around the heart) • Irregular electrical rhythms of the heart (arrhythmia)
Symptoms of CHF in Dogs Some of the symptoms of heart failure are related to • increased activity of the nervous system • increased concentrations of circulating hormones (and related chemicals). Symptoms include: • Coughing • Shortness of breath • Difficult breathing • Weightloss • Fatigue Arrows indicate the presence of fluid in the lungs
The Odds for Getting CHF • Lifetime risk – 20% (men and women) • CHF deaths far exceed cancer, HIV • Life expectancy following CHF • approximately 5 years • Overall median survival • 1.7 years in men • 3.2 years in women
Risk factors for CHF • High cholesterol levels in blood • Diabetes • Physical inactivity • Obesity • Smoking • Poor diet • High blood pressure (Hypertension) (>140-160 mmHg or >90 diastolic, or both) seen in 91% of people with CHF *** Both women and men are at risk, especially if they have any of the above risk factors
Options for Patients with CHF • Heart transplantation • Mechanical assistance • Total artificial heart
Review Questions • What is the difference between a heart attack and congestive heart failure? • What are three main risk factors for heart attacks? • What are three main risk factors for congestive heart failure?
Heart Valve Problems Tendon-like cords connect valves (underside at top) to walls of the heart and help hold the valves shut during contraction
Heart Murmurs • A heart murmur is an extra or unusual sound heard during a heartbeat. • There are many kinds of murmurs, some that are insignificant and some that indicate a heart problem is present.
Open Heart Surgery in a Child Small white ring is an artificial valve that is being lowered into heart.
Heartworms in Dogs • Heartworm disease is an infection of Dirofilaria immitis of the arteries and right side of heart • Heartworms are spread by mosquitoes • Dogs usually show no clinical signs! • Dogs should be wormed monthly for heartworms
Review Questions • What causes the sound of heart murmurs? • What are some causes of heart murmurs?
Breakdown the words: Patent: to make open Ductus: tube or canal Arterio: relating to an artery Put the words together to see that it means there is an artery that is open (that should be closed!) It is an artery that needs to be open in the fetus but needs to be closed in the adult Patent Ductus Arteriosus (PDA)
PDA in Canines • Most common canine congenital (present at birth) heart problem. • Affects 5 out of 1000 dogs, in any size or breed. • 65% of dogs with this problem will die by 1 year of age if it is not fixed. • Most have the problem diagnosed between 1 month and 3 ½ years of age.
PDA in Humans • The estimated incidence is from 6 out of every 100,000 live births up to 20 out of every 100,000 live births. • This incidence is increased in children who are born prematurely. • The death rate is very low except in extremely premature infants. • It occurs twice as often in girls as in boys.
Fetal Blood Flow Is DifferentWhy Does It Have To Be? After birth: blood must go through lungs Fetus: shunt bypasses lungs
Symptoms • Can a patient live normally? • Sometimes there are no symptoms • In large PDAs, symptoms can include: • Exercise intolerance • Sweating • Dyspnea (difficulty breathing) • Poor weight gain Audio of a normal heart Audio of a PDA murmur
Management Options for PDA • Observation and monitoring • Medical Management • Medications may be prescribed to reduce blood pressure, maintain normal heart rhythm, and prevent fluid overload. • Surgical • Surgical repair • Ligating (suturing closed) the artery • Catheter based occlusion • Placing a “coil” inside the artery to stimulate closure
Surgical Ligation Aorta PDA Pulmonary Artery
Catheter Based Occlusion • With a surgery called Transarterial Ductal Occlusion With Coils • Very safe procedure • Very successful procedure (95% success)
Transarterial Ductal Occlusion Aorta (with catheter inside) PDA Coil within PDA Pulmonary Artery *No dye visible in the pulmonary artery anymore!
Review Questions • Why is a PDA necessary in a fetus? • Why is a PDA undesirable in a newborn? • Why is the blood in a pulmonary artery in a PDA patient a mixture of oxygenated and unoxygenated blood?