Before the advent of echocardiography, the only noninvasive tools used to routinely evaluate the cardiovascular system were a thorough physical examination, electrocardiography, and thoracic radiography. Diagnoses that could not be readily procured from these techniques would ultimately require invasive procedures, such as angiocardiography, to further characterize the underlying disorder. While echocardiography has replaced diagnostic cardiac catheterization in most circumstances, its utility and easy access have also produced an untoward side effect: the cardiovascular physical examination appears to have fallen by the wayside.

We often underuse the auscultation and physical examination techniques our predecessors mastered to successfully evaluate the cardiovascular system. Instead, we lean on echocardiography to offset the subtle nuances we fail to recognize. This holds so true in the medical profession that echocardiography is considered by many to be an extension of the physical examination.¹ Nonetheless, cardiac auscultation still provides a cost-effective method of making serial observations, aids in the early detection of critical findings, helps intelligently guide the selection of costly diagnostic tests, and provides a therapeutic value of physical contact between physician and patient.²

In this article, I review the basic concepts and techniques necessary to perform a thorough cardiovascular physical examination. As with any other technique, a systematic approach enables you to effectively perform the examination and not miss a vital clue.

Begin the physical examination by carefully observing the patient from a distance. I frequently do this while recounting the history and current medical complaint. Although often overlooked, the observation period enables you to characterize the pet's general appearance, attitude, and respiratory rate and effort. If you forgo this step, you may not detect subtle changes that owners may have failed to recognize.

Patients with severe, chronic cardiac compromise may exhibit marked weight loss and muscle wasting along the temporal region of the head and along the dorsolumbar aspect of the spine. Other pets may present with abdominal distention or weight gain from ascites subsequent to right-sided heart failure. Reluctance to move in a normally active or nervous patient may signal substantial cardiovascular compromise. Similarly, tachypnea, dyspnea, coughing, or an orthopneic stance with an inability to lie comfortably may be associated with substantial fluid accumulation within or around the lungs.

EVALUATING THE HEAD AND NECK

This step of the physical examination involves a careful inspection of the mucous membranes, eyes, and neck.

Mucous membranes

Alterations within the oral mucous membranes often do not occur until late in the process of many cardiac diseases, but the appearance of the oral mucosa may yield valuable information when combined with findings from the remainder of the physical examination. Normal mucous membranes are pink and moist with a brisk (one- to two-second) capillary refill time after blanching the gums. Although the capillary refill time is a nonspecific and often crude index of cardiac performance, it may be prolonged in instances of reduced cardiac output.

In addition to estimating the capillary refill time, inspect the mucous membranes for pallor or discoloration. Cyanosis is seen when the deoxygenated hemoglobin concentration exceeds 5 g/dl.³ Cyanotic mucous membranes often signify arterial hypoxemia, as seen with severe pulmonary disease or right-to-left shunting of blood (e.g. tetralogy of Fallot). Cyanosis may also be seen in patients with normal arterial oxygen saturation complicated by decreased perfusion to peripheral vascular beds. Peripheral cyanosis is usually observed in the digits or ear tips of patients with reduced cardiac output, marked arterial vasoconstriction, or vascular obstruction. While peripheral cyanosis is more common in patients afflicted by shock or hypothermia, a common cardiac manifestation is hindlimb footpad cyanosis encountered in cats with aortic thromboembolism. Patients with cyanotic cardiac disease may also display injected mucous membranes subsequent to polycythemia.

Eyes

Acute blindness may be the first sign of systemic hypertension in a patient. This complication highlights the importance of inspecting the pupillary light responses and ocular fundus in patients with suspected systemic hypertension. Abnormalities that you may see include retinal detachment or hemorrhages, papilledema, or hyphema. Although infrequently recognized today, cats with dilated cardiomyopathy secondary to taurine deficiency may display central retinal degeneration.

Neck

Carefully inspect both the thyroid glands and the jugular veins before performing thoracic auscultation. Because of the connection between hyperthyroidism and the cardiovascular system, always palpate for enlarged thyroid glands in cats with suspected heart disease. As a consequence of the concentric hypertrophy and high cardiac output state associated with hyperthyroidism, cats with increased circulating thyroid hormone concentrations may have audible murmurs or gallop sounds.