Atrial Septal Defects
Prior to birth, a flapped oval aperture of the membrane connecting the atria permits shunting of blood from the right to the left side so as to go around the non-functional lungs. When the dog is born, the reduction in right atrial pressure forces the flapped oval aperture to seal and shunting to end. Elevated right atrial pressure may reopen the flap where the membranes have not closed, thus permitting shunting to begin again. This is not a proper atrial septal defect because the membranes have developed in a normal manner. A true atrial septal defect is a normal opening of the membranes, which permits blood to be forced from one atrium to the other.
In a majority of situations, blood flows from the left atrium to the right atrium, resulting in overworking of the right-sided chambers. Too much flow of blood via the right-sided chambers lead to their enlargement and thickening of their muscle fibres. Constriction of the pulmonary blood vessels might happen as a result of excessive pulmonary blood flow, thus resulting in rapid right-sided congestive heart failure. When right atrial pressure elevates shunting from right to left transversely through a gap that couldn’t shut, an atrial septal defect will form.
Symptoms include a murmur and arrhythmias. Electrocardiography and echocardiography can be used to create images of the defect, with the consequent results showing differing degrees of enlargement of the right atrium and right ventricle.
Surgical procedures in this case may prove to be very expensive, and there is no guarantee that the patient will survive the surgical treatment. Dogs with specific forms of defects can handle the defects effectively and many of these defects are only discovered when older animals are taken for their routine exams. However, other varieties of defects are more likely to result in right-sided congestive heart failure. Elevated blood pressure in the arteries of the lungs is also a possibility, with the prognosis for complete recuperation being difficult to predict in these cases.
Ventricular Septal Defects
Ventricular septal defects are gaps between the left and right ventricles of the heart. They could be of differing sizes and have different effects on blood circulation. Ventricular septal defects may appear in combination with other congenital abnormalities of the heart.
The most common effect of such a condition is shunting of blood from the left ventricle to the right one, due to generation of higher pressures in the left ventricle. Blood forced into the right ventricle is re-cycled via the blood vessels in the lungs and left heart chambers, causing enlargement of these vessels, as well as the right ventricle. Considerable shunting through the pulmonary arteries can encourage constriction of these vessels, resulting in diminished flow of blood or increased blood pressure. With increased resistance, the shunt may reverse and turn into a right-to-left shunt.
The symptoms displayed will depend on the severity of the defect and the direction of the shunt. Small defects usually cause few or no signs, while bigger defects may lead to extreme left-sided congestive heart failure. The indicative signs of a right-to-left shunt are a bluish tinge, tiredness, and inability to withstand exercise. Though most affected animals develop a loud murmur, a very large defect usually results in a murmur that is not easily heard. Chest x-rays, echocardiography (ultrasonography), and alternative expert techniques may be used to verify the defect.
Treatment of ventricular septal defects also relies on how severe the symptoms are and the direction of the shunt. For dogs with small ventricular septal defects, treatment is not necessary and the final outlook is normally good. For dogs with a modest to severe defect, symptoms usually develop and treatment is definitely an option. There are certain treatment options available for dogs that have a large ventricular septal defect and left-to-right shunting. One option is surgery to close the defect or to minimise shunting, while another is to administer drugs that will lower blood pressure. With right-to-left shunting, surgery is generally not an option. Bloodletting can be used to lessen the effects of excess number of red blood cells, while particular drugs could help to relieve some symptoms. However, the general prognosis in such cases is bleak. It is imperative that dogs suffering from ventricular septal defect never be used for breeding. This congenital abnormality has been proven to be hereditary in English Springer Spaniels.