DEPARTMENT OF CLINICAL MEDICINE ETHICS AND JURISPRUDENCE

COLLEGE OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY

ORRISHA UNIVERSITY OF AGRICULTURE AND

Physical examination of cardio vascular system and different technique use to diagnose the cardiovascular diseases

Submitted by Dr Abhishek Hota

1st yrVEPM

ADM NO-05VEPM/14SUBMITTED TO

Dr R. C. patra

H.O.D. OF Dept of clinical medicine ethics and jurisprudence

Physical examination of cardio-vascular system and different techniques used in cardio-vascular disease diagnosis

A complete and thorough physical examination is critical to every veterinary patient. In patients that present with a history or clinical signs indicative of cardiovascular disease, the physical examination is an irreplaceable tool in the diagnostic process.There are four way to examine1. Inspection ,2. Palpation 3. Auscultation 4. Percussion

1.Inspection…… Observe your patient, when it is relaxed and breathing normally if possible. Note any coughing, muscle wasting, or abdominal distention. Record the rate, depth, and effort of respiration. The normal respiratory rate in small animals is ~ 18 - 30 breaths/minute.

1. Tachypnea = increased respiratory rate2. Dyspnea = distressed and labored breathing

Inspiratory dyspnea is characterized by a prolonged, labored inspiratory effort, and aquicker, easier expiratory phase. Inspiratory dyspnea usually indicates an upper airwaydisorder.. Expiratory dyspnea is characterized by a prolonged, labored expiratory effort andindicates an intra thoracic airway disorder (e.g., chronic bronchitis, pulmonary edema due to congestive heart failure, etc.) and/or a restrictive disorder (e.g., pleural effusion). Intra thoracic disease will frequently cause both inspiratory and expiratory dyspnea.Orthopnea is a term applied to respiratory distress that is exacerbated by recumbency.Animals showing orthopnea assume a standing or sitting position with elbows abducted and neck extended. Movement of the abdominal muscles that assist ventilation is oftenexaggerated. Such animals vigorously resist being placed in lateral recumbency.

Examine oral, and ocular (+/- genital) mucous membranes. Mucous membranes allow you to assess hydration, cardiac output, and oxygenation. Normal mucous membranes are pink and moist, with a capillary refill time of < 2 seconds. Pale mucous membranes may indicate decreased cardiac output, anemia, or peripheral vasoconstriction. Peripheral vasoconstriction occurs with hypothermia and shock. Cyanotic mucous membranes (blue-colored) indicate an increase in the concentration of deoxygenated hemoglobin. Cyanosis is seen with right-to-left shunting defects (such as tetralogy of Fallot), severe respiratory disease secondary to any disorder impairing oxygenation, or marked hypothermia. “Differential” cyanosis describes patients whose oral mucous membranes are normal colored, but genital mucous membranes are cyanotic. This is a unique finding characteristic of a right-to-left shunting patent ductus arteriosus. Differential cyanosis occurs because the ductus arteriosus is “downstream” of the blood vessels which supply the head.

Examine the jugular veins. It is often necessary to clip the area over the jugular veins to visualize jugular pulsations or jugular distention, although persistent jugular distention can frequently be palpated. Persistent

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jugular distention is an important indicator of right heart failure. It is commonly seen with pericardial effusion, but also occurs with other causes ofright-sided congestive heart failure (e.g., dilated cardiomyopathy). A jugular pulse that extends more than about one third of the way up the neck usually indicates tricuspid regurgitation.

2.Palpation……

Thoracic palpation of the precordial impulse allows you to assess the strength and location of the apex beat. The apex beat is the point on the chest where you feel the heart beating the strongest against your hand. (The apex beat is sometimes incorrectlycalled the point of maximal intensity (PMI). The term PMI is used to describe the location of a murmur ). The left ventricular apex is the largest part of the heart and therefore the apex beat is normally found at or just below the costo-chondral junction in the left fifth intercostal space. A caudally displaced apex beat may indicate cardiomegaly, or a cranial mediastinal mass causing caudal displacement of the heart. A right-sided apex beat may indicate right-sided cardiomegaly, or a mass displacing the heart to the right. A hypokinetic apex beat suggests decreased contractility, or may be the result of obesity or pericardial effusion diminishing the precordial impulse. During palpation, note any vibration felt over the heart. This is called a thrill, and it is associated with turbulent blood flow in the heart. A thrill on palpation may be the first indication that a murmur is present.

3.Auscultation ……… Ideally, the animal should be standing during auscultation to maintain the normal anatomic position of the various valve areas of auscultation. All valve areas MUST be ausculted. Begin your cardiac auscultation at the apex beat. The apex beat is a convenient “landmark” for the mitral valve area of auscultation in normal animals. The aortic valve area of auscultation is located one intercostal space further cranially (i.e., left fourth intercostal space) just above the costochondral junction. The pulmonic valve area of auscultation is usually located one intercostal space further cranially (i.e., left third intercostal space) just above the sternum. The tricuspid valve area of auscultation is located on the right side at about the level of the costochondral junction between the third to fifth intercostal spaces. This is usually just across from the apex beat onthe left. One should also auscult the left side of the chest high in the axilla (about the second intercostal space). This is the location that the continuous murmur of a patent ductus arteriosus is heard best.

Begin auscultation by identifying the heart sounds. The first heart sound (S1) is produced by vibrations of the heart at the beginning of contraction, and is associated with closure of the AV valves. S1 is loudest over the mitral valve area, and is louder, longer, and lower pitched than the second heart sound (S2). S2 is produced by vibrations of the heart at the end of systole and is associated with closure of the pulmonic and aortic valves. S2 is heard loudest by moving the stethoscope cranially to the left heart base. S2 is shorter and higher pitched than S1. In dogs and cats (in contrast to horses and cows), it is

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always abnormal to hear the third and fourth heart sounds (S3 and S4). S3 is associated with rapid ventricular filling after the mitral valve opens in early diastole. S4 is associated with atrial contraction topping off the ventricle in late diastole. The presence of S3 or S4 is recognized when a gallop rhythm is heard during auscultation. While it is relatively easy to recognize a gallop rhythm , it is usually extremely difficult to know exactly which additional heart sound you are hearing (i.e. S3 or S4). To identify the precise nature of the gallop, phonocardiography is generally required. However, from a practical perspective, this distinction is of academic importance only. you have a gallop rhythm in a small animal, you have cardiac pathology which needs to be pursued. Muffled heart sounds may indicate the presence of pericardial or pleural effusion. It can also occur in animals that are overweight, or have intrathoracic masses.

Determine the heart rate. Normal heart rate for the dog ranges from 70 beats/min in larger dogs to as high as 220 beats/min in puppies. Normal heart rates for cats and kittens range from 140 - 240 beats/min. A slower than normal heart rate is termed a bradycardia, and a faster than normal rate is termed a tachycardia. Abnormalities in heart rate or rhythm must be identified and characterized. There are two normal rhythm variations in the dog. Normal sinus rhythm has regular beat with a normal rate. A normal sinus arrhythmia has a normal to slow heart rate, and is characterized by cyclic increase and decrease in heart rate. This is sometimes specifically associated with respiration, and results in an increase in heart rate during inspiration and a decrease in heart rate with expiration. Respiratory sinus arrhythmia is common in dogs, but very uncommon in the cat. Sinus arrhythmias are associated with increased vagal tone, and are usually a sign of a health heart. However, a very exaggerated sinus arrhythmia can occur secondary to other disease processes, the most common of these being chronic gastrointestinal disease, chronic pulmonary disease, increased intracranial pressure, and increased intraocular pressure. Common rate and rhythm abnormalities include the following:

Beats that occur prematurely, and that are associated with pulse deficits. These are termed extra systoles (e.g., atrial and ventricular premature complexes).

Bursts or runs of extrasystoles are termed paroxysmal tachyarrhythmias (e.g., with paroxysmal atrial and ventricular tachycardia).

A remarkably irregular tachyarrhythmia is termed a chaotic tachyarrhythmia (e.g., as occurs with atrial fibrillation).

A persistent regular tachycardia (e.g., with a continuous supraventricular or ventricular tachycardia) or a persistent regular bradycardia (e.g., with complete AV block).

Any abnormality in heart rate and/or rhythm that is detected during auscultation is a clear, unambiguous indication to perform electrocardiography to determine the precise nature of the rate and/or rhythm abnormality.

The canine heart projects into both thoracic cavities, particularly the left, from the third to the sixth intercostal space. The long axis of the heart is rotated cranially so that it lies at an angle with the base more cranial than the apex. The base of the heart is fixed by the great veins and arteries while the apex can move freely within the pericardial sac. The so-called right and

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left sides of the heart are more correctly understood to be the dextro-cranial and levo-caudal sides because the left ventricle lies behind and slightly left of the right ventricle. The left ventricle is more conical and massive than the right ventricle which is more crescent shaped. Landmarks If the dog is standing square, much of the heart lies medial to the triceps mass. A horizontal line drawn through the point of the shoulder lies slightly above the level of the heart valves. As opposed to using features of the forelimbs (e.g. the point of the shoulder and position of the olecranon) to locate heart valves, palpation of the apex beat is more accurate because its position is independent of the dogs forelimbs.

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Internal landmarks for the heart valves largely rely upon their positions relative to intercostal spaces and costochondral junctions. The following guidelines (Tilley and Goodwin, 2001) may be helpful for auscultation:

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The Apex Beat The apex beat is an impact vibration produced at the start of ventricular contraction as the heart hits the chest wall. In the normal dog it is palpated on the left side, ventrally in about the fifth intercostal space. The apex beat should be identified by palpation before the heart is listened to. It is important in lesion localization because the mitral valve lies close by and S1 is loudest at this point.

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Palpation of the Apex Beat

Cardiac Auscultation Cardiac auscultation should be performed in a quiet room free of excessive noise. Cardiac auscultation should also be performed as soon as the animal enters the exam room or when the dog is stressed since this increases the probability that a transient or subtle murmur will be detected. The probability of detecting a murmur increases with stress because sympathetic activation increases heart rate, cardiac contractility and cardiac output. Turbulent flow, which gives rise to murmurs, is more likely at higher blood velocities. Cardiac auscultation should proceed in a logical manner. The apex beat (mitral valve area) should be palpated and the heart rate measured either by cardiac auscultation or palpation of the femoral pulse. The femoral pulses should be palpated in each hindlimb and compared for fullness, sharpness and regularity. Next the femoral pulse should be palpated simultaneously with cardiac auscultation in order to detect pulse deficits due to arrhythmias. Each valve should be ausculted in the order Mitral, Aortic, Pulmonic (acronym MAP). Some palpate the apex beat (mitral valve area) and move cranially from there. However, if you wish to auscult in a particular intercostal space it is easier if you start counting spaces from the last rib (13th) cranially.

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Basic Cardiac Function The cardiac cycle consists of two phases: Systole (ventricular contraction) and diastole (ventricular relaxation). At rest, systole occupies one-third of the cardiac cycle while diastole occupies two-thirds of the cardiac cycle. The normal rhythm originates from the sino-atrial node. When the rhythm is completely regular (the timing of the heart sounds remain in a uniform, repeating cycle) it is called a normal rhythm. Sinus rhythm refers to the normal rhythmic contractions of the heart initiated after the sino-atrial node discharges. It may be completely regular or the interval between beats may wax and wane. This is referred to as sinus arrhythmia and is normal in dogs. An ECG (electrocardiogram) is required to confirm the presence of sinus rhythms or arrhythmias. In the following table the width of the columns

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represent the duration of the audible characteristics of the cardiac cycle.

Audible Sounds Detected During Aucultation Research has revealed that there are four main sounds produced during the cardiac cycle of which only the first and second are normally heard in canines. The third and fourth heart sounds are pathological if ausculted. Normal S1 - The first heart sound (lub) is the result of the closure of the left and right atrioventricular valves (mitral or bicuspid and tricuspid valves respectively). S2 - The second heart sound (dup) is the result of the closure of the pulmonic and aortic (semilunar) valves. Pathological S3 - The third heart sound is the result of the addition of more blood into a partially filled ventricle thus creating turbulence and sound waves. S4 - The fourth heart sound is the result of atrial contraction. Although S4 is labelled the fourth heart sound; if present; it will be heard at the start of the cardiac contraction cycle.

The First and Second Heart Sounds Listen to the recordings of isolated heart sounds and see if you can detect the differences in duration, intensity and pitch. S1 is slightly longer in duration and of lower pitch than S2. More reliable clues are the timing of the sounds and that S1 is louder than S2 when you listen at the apex beat (Left4).

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A Comparison of S1 and S2

The Third and Fourth Heart Sounds In canines, the third and fourth heart sounds (S3 and S4) are not heard in normal animals and their presence is an indication of pathology. The presence of S3 is often associated with dilated cardiomyopathy (DCM) or chronic volume overloads due to acquired mitral insufficiency while S4 is associated with hypertrophic cardiomyopathy, pressure overloads (semilunar valvular stenosis) or chronic hypertension (Fox, 1988). Since S3 and S4 are both low frequency sounds, they are best heard with the stethoscope bell.

Qualities of S3 and S4

Other Normal Sounds Other normal sounds include those sounds produced by the gastrointestinal tract and the

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respiratory tract. Both gut and respiratory sounds are clearly distinguishable from cardiac sounds. The gut sounds will be variable and irregular in timing while the respiratory sounds are consistent and regular in timing.

Artifactual sound During cardiac auscultation you can hear additional sounds produced by movement or the environment. In order to eliminate these sounds the location where auscultation is being performed should be free of excessive noise, the dog should be properly restrained and the vet should take care in handling the stethoscope. To reduce the sound of hair rubbing against the stethoscope, the dogs coat may be moistened with alcohol over the target area.

Normal Resting Heart Rate Values for Canines The "normal" heart rate for canines varies with the age, physical size, breed, level of arousal and physical condition of the animal . Smaller dogs have faster heart rates than larger ones.

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Compare the recordings from an adult Poodle with that from a Greyhound, and use your watch to practice taking the heart rate. As a general rule, clinicians will take the heart rate over a period of 10 or 15 seconds depending on how tachycardic the animal is.

Arrhythmias An arrhythmia or dysrhythmia is a deviation from the regular rhythm. In dogs this may be normal or abnormal and may result from abnormal cardiac impulse formation, conduction, rate or regularity. Regularity Regularity refers to the predictability of an arrhythmia. Some arrhythmias occur in a predictable fashion and are said to be regularly irregular. These rhythms may be normal (e.g. sinus arrhythmia) or pathological. In others the onset of the next beat is completely unpredictable and the rhythm is said to be irregularly irregular (e.g. atrial fibrillation). Irregularly irregular rhythms are pathological in origin.

Classification of Arrhythmias OriginSupraventricular arrhythmias arise from the atria or AV node whereas ventricular arrhythmias arise from the ventricles. RateArrhythmias with slow rates are bradyarrhythmias while those with fast rates are tachyarrhythmias. RegularityFibrillation is a rapid, irregular, chaotic rhythm while tachycardia is a rapid but regular rhythm.

Normal Sinus Impulse Formation Sinus Arrhythmia Sinus arrhythmia is a regularly irregular sinus rhythm which is a normal finding in most dogs

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(especially brachycephalic breeds). SinusArrhythmia is characterized by slight variations in the S1-S1 interval. These variations are related to changes in vagal tone to the heart and are often associated with inspiration (negative pressure created in the thorax) or use of sedative or anesthetic drugs. You can demonstrate sinus arrhythmia by palpating the radial artery on your wrist. Once you feel your pulse take a big deep breath and you should feel your pulse quicken and then slow down as you exhale.

Altered Sinus Impulse Formation Sinus Bradycardia (Slow Heart Rate) Sinus bradycardia has a regular rhythm and may result from systemic disease (renal failure), toxicities, increased vagal tone, elevated intracranial pressure or compression of the eyeball, hypothermia, hypothyroidism or drugs (tranquilizers, propranolol, morphine, various anesthetics) Sinus bradycardia is diagnosed when the heart rate is less than 65 beats / minute and an ECG shows sinus rhythm.

Sinus Tachycardia (Increased Heart Rate) Sinus tachycardia; often caused by stress; is the most common arrhythmia observed in dogs and has a regular rhythm. Sinus tachycardia may result if there is increased metabolism and oxygen demand or increased requirement for cardiac output (pain, fright, excitement), pathology (fever, shock, anemia, hypoxia, hyperthyroidism) or pharmacological agents (atropine, epinephrine, ketamine) . Sinus tachycardia is diagnosed when the heart rate is greater than 160 beats / minute for most dogs (>180 bpm for small / toy breeds or >220 bpm in puppies) and an ECG shows sinus rhythm

Altered Supraventricular Impulse Formation Atrial FibrillationAtrial fibrillation is a common pathological arrhythmia in dogs . Auscultable characteristics of atrial fibrillation include a completely unpredictable rhythm, sometimes called a "jungle-drums" rhythm. Listen for long diastolic pauses between some beats and very short intervals between others. Sometimes the beats are so close together that S2 is not generated and two S1 sounds follow each other. The other hallmark of atrial fibrillation is a pulse deficit. Sometimes this can be detected because there is a large disparity between the heart rate and the pulse rate. If the heart beat is slow it is more reliably detected by simultaneous auscultation and palpation of the pulse. Normally every S1 heart sound is followed by a pulse wave.

Abscence of a wave is called a pulse deficit.

The most common causes of atrial fibrillation are chronic atrioventricular valvular insufficiency in small breeds, dilated cardiomyopathy in large breeds, and congenital heart defects. Less common causes include heartworm disease, cardiac trauma, digitalis toxicity and severe metabolic disorders . Auscultable or palpable characteristics of atrial fibrillation include inconsistently filled femoral pulses, detection of an S1 without an S2 and a pulse deficit.

Disrupted Impulse Conduction

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Second Degree Atrioventricular (AV) Block Second degree AV block may be of two types: Mobitz I, usually type A or Mobitz II, usually type B. The two types of second degree AV block are best distinguished by ECG. Mobitz I is a normal finding in dogs, especially in young animals and disappears with exercise. Mobitz II is pathological in origin and will not disappear with exercise. Both types of second degree AV block are manifested by a dropped beat detectable during auscultation. By exercising and immediately ausculting the dog, you can determine if the AV block is a Mobitz I (the dropped beats have disappeared) or Mobitz II (the dropped beats are still auscultable). Second degree AV blocks can be associated with sinus arrhythmia, increased vagal tone, supraventricular tachycardia, electrolyte imbalances or drugs (digitalis, intravenous atropine, xylazine)

Murmur Murmurs are sounds produced by turbulent blood flow. Rapid flow, a wide vessel, low blood viscosity and an uneven or constricted vessel wall all predispose to cardiac murmurs. They can be physiological, for example high blood flow though the aortic outflow tract. Pathological murmurs reflect heart disease, for example degeneration and roughening of a valve surface. Veterinarians require a uniform method of describing murmurs to facilitate communication between each other via a common understanding. Five parameters have been developed that serve to describe all of the important aspects of a murmur. Of the five parameters, the most important ones are position in the cardiac cycle, intensity, duration and pattern of intensity. The point of maximal intensity (PMI) identifies the location where the murmur is heard loudest and is often described using the valve location nearest (e.g. Mitral valve area). In describing the duration of murmurs, pan refers to a murmur that obliterates both heart sounds either through systole or diastole but does not obliterate any heart sounds. Holo refers to a murmur that lasts throughout stystole or diastole but does not obliterate any heart sounds. A continuous or machinery murmur lasts throughout most or all of systole and diastole and may or may not obliterate heart sounds. Early- and late- describe murmurs that are positioned closer to one heart sound than to another. Crescendo, decrescendo or diamond are terms that describe the intensity profiles of murmurs as increasing, decreasing or increasing and then decreasing in loudness. Musical and blowing and are terms used to describe the frequency profile of a murmur. Grade refers to the absolute intensity of murmurs determined on a 6 point scale where the higher the grade the more severe the murmur (Example: Grade 2 versus a grade 5 regurgitant murmur).

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Research shows that most clinicians correctly describe the grade of a murmur. Localization of the murmur to systole or diastole is less consistent. A clue is the timing of the heart sounds (systolic murmurs occur in the short pause), however loud murmurs can be perceived as being of longer duration than they really are . Another useful method is to palpate the pulse during auscultation. Pan- or holo-systolic murmurs should be heard coincident with the pulse wave.

Problems and Strategies for Murmur Localization On the left side, the pulmonic and aortic roots lie next to each other and it is difficult to separate their respective valvular sounds.

Both produce sounds that are best heard cranio-dorsally on the left side of the thorax at the second or third intercostal spaces. Since the aortic valve is more centrally located and produces louder sounds some aortic murmurs are also heard on the right side. Mitral valve problems produce sounds that are heard more caudally centered on the fourth or fifth intercostal space. On the right side, tricuspid and ventricular septal defects produce murmurs that are heard ventrally around the fourth or fifth intercostal space. A problem with localizing the origin of murmurs is that loud murmurs can radiate over a wide area and on both sides of the thorax. Despite this, the point at which they are loudest is often close to the lesion.

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Sometimes it may prove challenging to correctly identify the likely origin of a murmur. Generally by following a logical process like the one outlined here, insight may be gained into the type of murmur being dealt with. First of all the stethoscope should be moved around to all the valve areas on each side of the thorax in order to ascertain where the PMI is located and which; if any; valve is involved. With the location of the PMI known the murmur's intensity may be accurately graded and the character and quality judged. Finally, by simultaneously ausculting the PMI and palpating the femoral pulse an accurate indication of the position and duration of the murmur within the cardiac cycle may be obtained. Additionally, note that by examining the animal as soon as it enters the exam room or when it is stressed, the probability of detecting a transient or subtle murmur increases because the intensity increases in accordance with the sympathetic effects of stress.

The Most Common Murmurs Afflicting Dogs and their Features In order of prevalence: Mitral Regurgitation Mitral Reguritation, the result of mitral insufficiency, allows backflow of blood into the left atrium. Typical features of mitral regurgitation include a normal to increased arterial pulse, a PMI located at the left apex, a plateau or decrescendo quality and systolic position in the cardiac cycle. Mitral regurgitation is most often the result of acquired valvular disease (e.g. mitral valve endocardiosis) and is usually observed in older dogs. Patent Ductus Arteriosus Patent ductus arteriosus results when the ductus arteriosus fails to close properly (functional closure normally occurs by 72 hours after birth while anatomic closure is complete within the first few weeks). PDA is therefore most commonly seen in young dogs with a higher prevalence in purebreds and females . This murmur will feature an increased arterial pulse, a normal to increased venous pulse, a PMI located at the left base and a machinery or continuous quality as it is present throughout most or all of systole and diastole .

Tricuspid Regurgitation Tricuspid regurgitation, the result of tricuspid insufficiency, allows backflow of blood into the right atrium. Like mitral regurgitation, tricuspid regurgitation is most often caused by acquired valvular disease and is usually observed in older animals. Features of a tricuspid regurgitant murmur include an increased venous pulse, a PMI located at the right apex, a plateau or decrescendo quality and a systolic position in the cardiac cycle . The following two diagrams represent the locations where specific cardiac pathologies will be auscultated best.

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Heart murmurs are classified according to several criteria. Murmurs are caused by turbulence disturbing the normal laminar flow of blood. They are most often caused by dysfunctional valves or septal defects. Characterization of murmurs is based on several criteria, of which timing in the cycle, location or point of maximal intensity (PMI) of the murmur, and intensity (loudness) are the most important.

Timing and duration in the cycle: If the murmur occurs between S1 and S2, it is systolic (common in small animals). If it occurs between S2 of one beat, and S1 of the following beat, it is diastolic (extremely uncommon in small animals).

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A murmur is early systolic if it ends by mid-systole. The same duration criteria are applicable to diastolic murmurs, although most do not extend throughout diastole. Continuous murmurs (e.g., such as heard with left-to-right shunting patent ductus arteriosus) are heard throughout the cardiac cycle, and peak in intensity at about the time of S2.

Location and radiation: Location (or PMI) refers to the position of the stethoscope at which the murmur is heard the loudest. We frequently describe location as the valve area at which the murmur is heard loudest, e.g., “the murmur is heard loudest at the mitral valve” or “at the pulmonic valve”. Alternatively, less specific descriptions are used such as “the murmur is heard loudest at the left apex” (typical for mitral regurgitation), or “far forward and high over the left heart base” (typical for a left-to-right shunting patent ductus arteriosus). In addition to PMI, most pathologic murmurs radiate to other areas. Correct recognition of the PMI and pattern of radiation is can be very helpful in identifying the specific cardiac abnormality.

Intensity or loudness: Grade 1/6: Softest murmur audible in a quiet room after minutes of listening Grade 2/6: Soft, readily heard, but focal over one valve only Grade 3/6: Prominent, easily heard, radiates to other areas Grade 4/6: Loud, radiates widely, but not accompanied by a palpable thrill Grade 5/6: Loud and accompanied by a palpable thrill Grade 6/6: So loud that it can be heard with the stethoscope held off the thorax The intensity scale is subjective. Classification of a murmur can vary between observers especially when different stethoscopes are used (e.g., the diameter of the stethoscope diaphragm will make a considerable difference in the loudness of a murmur). Murmurs which occur in a structurally normal heart are called as innocent, physiological, or functional. Innocent murmurs are often heard in young puppies and kittens as soft systolic murmurs heard best at the mitral or aortic valves. These murmurs do not radiate, and they should disappear by 3 to 4 months of age. The cause of innocent murmurs is not known, but is possibly related to the lower packed cell volume of young animals. Physiological murmurs or Functional murmurs are common in animals that are anemic and occur as a result of changes in blood viscosity (which results in disruption of normal laminar blood flow). These are soft murmurs that resolve with resolution of the underlying disease. Occasionally, otherwise healthy animals with very vigorously beating hearts will also have physiologic murmurs. Pathologic murmurs are secondary to valve abnormalities or septal defects. Often, it is not possible to distinguish physiologic from pathologic murmurs on physical examination, and additional diagnostics are needed. The loudness of a murmur does NOT necessarily correlate with the seriousness of the defect.

Less common heart sound abnormalities include splits and clicks. Usually, the right and left AV valves (tricuspid and mitral) close almost simultaneously, so that only one heart sound (S1) is heard.Similarly, the semilunar valves (pulmonic and aortic) close nearly simultaneously producing a single S2. However, splitting of the heart sounds will occasionally be detected. Splitting of S2 due to delayed closure of the pulmonic valve is the most commonly detected split heart sound in dogs and cats. Pulmonary hypertension (e.g., as occurs with heartworm disease) is the most important cause of S2 splitting. Split S1 sounds are very rare and usually due to a conduction

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abnormality. A systolic click is an extra heart sound that is occasionally heard between S1 and S2 during systole. They are usually mid to late systolic sounds, relatively high pitched, and labile. The exact cause of systolic clicks is not known, but they are thought to be due to buckling of themitral or tricuspid valves in early degenerative valve disease. Clicks are most common in small breed, older dogs.

Auscultation of the respiratory system must be systematic and complete. Ideally, the animal should be standing and relaxed when you perform auscultation of the respiratory system and they should not be panting. If necessary the animal’s mouth must be gently held shut during auscultation. The entire thorax should be systematically ausculted. Normal breathing should be almost silent.The following terminology is used to describe abnormal lung sounds: Crackles (which are frequently classified as course or fine) are discontinuous sounds usually heard during inspiration. Crackles are caused by various pulmonary disorders (e.g., chronic bronchitis, pulmonary edema) in which some of the smaller airways are collapsed during the early phase of inspiration, then suddenly open with a crackling sound as inspiration progresses. Crackles with a low to normal heart rate suggest primary pulmonary disease (increased vagal tone). Crackles with an elevated heart rate suggest congestive heart failure (increased sympathetic tone). Wheezes (which may be further classified as high-pitched and low-pitched) are continuous musical or whistling sounds generated by air passing through narrowed airways (e.g., with intrathoracic tracheal collapse). Wheezes that arise from intrathoracic disorders are usually more pronounced during expiration. Muffled breath sounds may occur with conditions such as pleural effusions. With a pleural effusion, careful auscultation of your patient in the standing position will frequently reveal a fluid line - normal breath sounds in the dorsal lung fields, and muffled breath sounds in the ventral lung fields. Bronchovesicular sounds – this is the sound of increased air movement. It can be a normal finding in an animal breathing heavily, or may be a sign of early pulmonary abnormalities.

Pulses are characterized in terms of rate, rhythm, and quality. At some point during auscultation, it is very important to simultaneously palpate the pulses. The femoral artery is usually the most convenient to locate. Pulses should be synchronous with cardiac auscultation. In a patient with a normal rhythm, the heart rate and pulse rate will be equal. Pulse deficits indicate an arrhythmia is present. Assessment of pulse quality can be very useful. Hyperkinetic pulses are excessively strong. These occur in states of increased cardiac output such as anemia, and with a left-to-right shunting patent ductus arteriosus.

Hypokinetic pulses are those that are weak. This occurs with poor cardiac output and subaortic stenosis. The term variable (or sometimes unequal) is used to describe pulses that vary in strength from one beat to the next (e.g., with atrial fibrillation). It is important to remember that palpation of the pulse does not estimate the blood pressure, as you are merely palpating the difference in systolic to diastolic pulse pressure.

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Abdominal palpation may reveal signs of right-sided congestive heart failure. Right sided congestive heart failure leads to congestion of the abdominal viscera, which may manifest as hepatomegaly and ascites. Ascites is recognized on physical examination as abdominal distention with a fluid wave. Consequently, a thorough abdominal palpation forms an integral part of a complete examination of the cardiovascular system.4.Percussion: It is done to see the enlargement of the dullness of the cardiac region

Left border- apex Right border- right sternal margine

Cardiac causes: cardiomegaly, pericardial effusion, pulmonary artery dilatation, dilated cardiomyopathy.See if the dullness extends beyond apical impulse as in case of pericardial effusionRespiratory causes: pleural effusion, hydropneumothorax, collapse fibrosis.To find out cause of displaced heart due to lungs conditionPresence of diaphragm hernia and eventration of diaphragm could be suspected.

Other techniques used to diagnose cardiovascular diseases Cardiovascular diseases are diagnosed using an array of laboratory tests and imaging studies. The primary part of diagnosis is medical and family histories of the patient, risk factors, physical examination and coordination of these findings with the results from tests and procedures.

Some of the common tests used to diagnose cardiovascular diseases include:

Blood Tests

Laboratory tests are used to detect the risk factors for heart diseases. These include detection of the fats, cholesterol and lipid components of blood including LDL, HDL, Triglycerides.

Blood sugar and Glycosylated hemoglobin is measured for detection of diabetes. C-reactive protein (CRP) and other protein markers like Apolipo protein A1 and B are used to detect inflammation that may lead to heart diseases.

During a heart attack, heart muscle cells die and release proteins into the bloodstream. Blood tests can measure the amount of these proteins in the bloodstream. High levels of these proteins are a sign of a recent heart attack.

One of the markers of heart attack is the Cardiac Troponin-T. Other biomarkers include fibrinogen and PAI-1, high levels of homocysteine, elevated asymmetric dimethylarginine and elevated brain natriuretic peptide (also known as B-type) (BNP)

EKG/ECG (Electrocardiogram)

This is a simple and a painless test that records the heart’s electrical activity. The patient is strapped to the instrument with several patches or leads placed over his or her chest, wrists

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and ankles. A small portable machine records the activities of the heart on a strip of graph paper.

The test shows how fast the heart is beating and its rhythm. The strength and timing of the electrical signals as they pass through the heart are also seen. An EKG/ECG can help detect a heart attack, attacks of angina, arrhythmias etc.

Stress Testing

For this test, the patient is made to work hard e.g. run on a treadmill or exercise while the leads of EKG/ECG are placed over their body. Those who cannot exercise are given pills to raise their heart rate. The test detects the effects of the exercise on the heart.

In patients with atheroisclerosis and coronary heart diseases the arteries that are narrowed by plaques cannot supply adequate blood to the heart muscles while it is beating faster. This may lead to shortness of breath and chest pain. The EKG/ECG pattern, arrhythmias etc. also show the possibility of a coronary artery disease.

Echocardiography

This test uses sound waves to create a moving picture of the heart. This is also a painless test where a probe is rolled over the chest and the machine creates the image of the heart on the monitor. This provides information on the shape, size, workings, valves and chambers of the heart.

Echocardiography may also be combined with Doppler to show the areas of poor blood supply to the heart. It shows the areas of the heart muscle that are not contracting normally, and previous injury to the heart muscle.

Coronary Angiography and Cardiac Catheterization

This test is an invasive test. A dye is injected into the veins to reach the coronary arteries. This is done via coronary catheterization. Thereafter detailed pictures of the blood vessels of the heart are taken using special imaging methods. This is called coronary angiography.

Cardiac catheterization involves threading of a thin, flexible tube called a catheter via a blood vessels in the arm, groin (upper thigh), or neck. The tube is inserted under imagin guidance till it reaches the heart. Coronary angiography detects blockages in the large coronary arteries.

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Chest X Ray

This is a test that shows the shape and size of the heart lungs and major blood vessels. This is a test seldom used in diagnosis of heart diseases as it does not provide added information over echocardiography and other imaging studies.

Electron-Beam Computed Tomography or EBCT

EBCT helps to detect the calcium deposits or calcifications in the walls of the coronary arteries. These are early markers of atherosclerosis and coronary heart disease. This is not a routine test in coronary heart disease.

Cardiac MRI

Cardiac MRI (magnetic resonance imaging) that uses radio waves, magnets, and a computer to create pictures of the heart. This gives a 3D image of the moving as well as still pictures of the heart.

PhonocardiographyIt allows the recording and measurement of heart sounds. A special microphone is placed directly over the various ares of the thorax used for heart auscultation and heart sound is recorded graphically on moving paper or on a oscilloscope

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