Volume 40 | Issue 2 Article 3

1978 Patent Ken Grossman Iowa State University

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Recommended Citation Grossman, Ken (1978) "Patent Ductus Arteriosus," Iowa State University Veterinarian: Vol. 40 : Iss. 2 , Article 3. Available at: https://lib.dr.iastate.edu/iowastate_veterinarian/vol40/iss2/3

This Article is brought to you for free and open access by the Journals at Iowa State University Digital Repository. It has been accepted for inclusion in Iowa State University Veterinarian by an authorized editor of Iowa State University Digital Repository. For more information, please contact [email protected]. Patent Ductus Arteriosus Ken Grossman, E.C. F.V.G.*

Summary the lungs, the resistance (in the pulmonary arteries) drops. Simultaneously the left A 10 month old female mixed breed dog ventricle assumes the role of the major was presented to the ISU Veterinary Clinic for pumping chamber surpassing the right an ovariohysterectomy. A patent ductus ventricular pressure. As a consequence to arteriosus was diagnosed and surgically these changes, the assumes corrected. Aortic pressures and angiocar­ adult characteristics. The flow across diographic studies were also performed. the ductus arteriosus in the normal will stop at birth or shortly after, and the Introduction ligamentum arteriosus will form. If the ductus fails to close for some reason, it Patent ductus arteriosus (PDA) is the most becomes a patent ductus arteriosus (Fig. 1). common congenital cardiac defect seen in the With a PDA the rising postnatal presure in canine. It has been determined that approx­ the surpasses the imately 0.6% of the dogs seen in veterinary pressure, reversing the flow of blood across school clinics will present some form of con­ the ductus. This reversal causes an arterial­ genital cardiac disease and more than 30 % of venous (A-V) shunting in both and these will be PDA's. The defect is twice as , decreasing the total output in common in females as males and is most often systemic circulation. This type of A-V shunt seen in purebred dogs, especially in Poodles, or fistula is the most common in dogs. Collies, Pomeranians, and Shetland Sheep­ Compensatory increases in blood volume and dogs. 4 increases in left ventricular output are re­ Recognition of PDA is important for quired to maintain normal systemic cardiac several reasons. Since it is usually detected in output. Typically on auscultation an accen­ purebred pups, newly acquired animals could tuated late systolic and early diastolic mur­ presumably be returned. Early detection is mur is heard and termed a continuous or important to ascertain the extent of cardiac machinery murmur. Pulmonary arterial compensation for the defect and the pressure should always be greater than right feasibility of surgical correction. From the ventricular pressure in this condition. In surgical standpoint, the earliest possible severely compensated , pulmonary detection involves the least risk and the best hypertension can develop, and only a systolic prognosis. Since PDA is an inheritable defect murmur occurs since the left-to-right shunt is in some breeds, perspective breeders should limited to the systolic phase. When the be made aware ofits existence. 2 pulmonary arterial pressure is equal to or ex­ PDA is a persistent terminal portion of the ceeds aortic pressure, reverse (right to left) sixth aortic arch. Prenatally the ductus ar­ shunting or bidirectional shunting occurs. In teriosus is a short arterial connection this case there may be no murmur heard at bypassing blood from the pulmonary artery to all, but a split second heart sound may be the distal aorta and systemic circulation, recognized. 2 thereby circumventing the nonfunctional The defective closure of the ductus is a lungs. Normally at birth with the inflation of graded phenomenon. A partial closing, called a ductus diverticulum, can be recognized *Dr. Grossman is a 1977-78 E.C.F.V.G. Intern, Department of Veterinary Clinical Sciences, College of only with angiocardiography. In this con­ Veterinary Medicine, Iowa State University. dition there is no shunting nor auscultatable

48 Iowa State University Veterinarian that the pulmonary arteries were somewhat enlarged, but that no alveolar changes in the lung field were evident. LS An EKG revealed high amplitude R waves BA and deep Q waves. The heightened R wave (3 ~ mv) was present with a normal mean PC electrical axis, which indicated left ven­ tricular enlargement. The deep Q wave suggested right ventricular enlargement. Radiographic and electrocardiographic studies were compatible and confirmative of the initial PDA diagnosis. Because the dog Fig. I: Diagramatic representation of Patent presented no clinical signs indicative of heart Ductus Arteriosum. Legend: LS, Left Sub­ clavian Artery; BA, Brachiocephalic Artery; A, disease and the compensated heart showed no Aorta; PDA, Patent Ductus Arteriosum; PA, arrhythmic activity, it was determined that Pulmonary Artery; RV, Right Ventricle; RA, the dog would be a fair to good surgical risk. Right Atrium; LA, Left Atrium; LV, Left The stresses of an OHE or of parturition Ventricle; PC, Pericardium. would probably be too great for the dog to survive without corrective . murmurs. The patency may vary from a small Without any surgery the life expectancy was channel to the size of the aorta. Usually the estimated to be a maximum of 3 years. The larger the PDA shunt the more severe will be owner elected to donate the dog to ISU. the clinical manifestations. It has been On February 13, 1978, angiocardiography determined that, whether the dog has a and cardiac surgery were performed. Aortic clinically or nonclinically apparent PDA, the pressure and pulse were recorded throughout defect will present itself in equal inheritance both procedures. The dog was not given any in the offspring.4 premedication prior to anesthesia. Atropine, it was felt, would inactivate the possibility of Case Report cardiac response in the event of rapidly in­ creasing . Barbiturates were On February 9, 1978, a 15 lb., ten-month­ avoided because they often produce ven­ old female mixed breed dog was presented to tricular arrhythmias in normal dogs. The dog the ISU Veterinary Teaching Hospital for an was masked down with halothane and nitrous ovariohysterectomy (OHE). The owner was oxide and intubated. worried that the dog may have been bred two weeks before. No further pertinent history was given. During the admitting examination, ascultation revealed an ab­ normally loud first heart sound and a systolic murmur over the mitral area. Moving cranially over the pulmonic area, a diastolic murmur blended with the systolic murmur, producing a continuous or machinery murmur. The dog was hyperactive and with minimal excitement the murmur became easily identifiable over the entire heart field. A lateral radiograph revealed generalized with rounded right and left borders. The cardiac shadow was spread over four intercostal spaces. Elevation of the trachea was seen throughout its entire thoracic course. In a dorsoventral radiograph an aneurysmic bulge on the aortic shadow Fig. 2: Angiogram showing shunting of and slight bulging of the left atrial border contrast media from the aorta to the pulmonary were seen. From both views it was determined artery.

Issue No.2, 1978 49 ...... - " I f I A A i\..! , I ~f 120 ~ \ 1\ !\ J 1\ !L I '-J \ 1\ 1 \ 1 \ I\ II \ J " 100 .a.. \ 1 r \1 \f \ ~ 'J "," ,"- 'J , V l ~ "- 80 "'-I ""~ '"'- 60

40 I I I 20 ~..... - ...oIL -, - - --y - ...... - ...- ""V" 10 " o r A B c I ~ 1 sec ~ t ligation of ~ D.A. Fig. 3: Aortic blood pressure and Lead II (B) and 30 minutes following (C) ligation of Electrocardiogram before (A), immediately after PDA.

A #5 French multihole radiopaque catheter During surgery the catheter was left in the was introduced into the left carotid artery aorta and pressures and pulses were con­ after the area had been prepared. Using tinually monitored. After surgical image intensification the catheter was preparation, the left thorax was incised from retrograded through the brachiocephalic the wing of the scapula to the costochondral artery and the aorta into the left ventricle. junction. The thorax was entered through the During this procedure aortic and ventricular left fourth intercostal space. After adequate pressures were monitored on a VR-6 recorder positive pressure ventilation was attained, (Electronics for Medicine). The pressures aortic was recorded to be 35 were 78/42 mm Hg (normal 107/86 mm Hg) mm Hg. The approach to the pericardium and 80/10 mm Hg (normal 122/41 mm Hg) was made by reflecting the lung lobes respectively. The left ventricular end diastolic caudally. At this point the PDA was localized pressure was recorded at 30 mm Hg, which both visually and by palpation. The was considered high and approaching left pericardium was carefully incised between the . left vagus and phrenic nerves. These two With the catheter placed in the left ven­ nerves were retracted from the surgical field tricle, contrast medium (Hypaque M-75,® with 3-0 silk traction sutures. After dissecting

Winthrop) was rapidly injected with a CO2 around the caudal and ventral aspects of the powered syringe. Immediately after the PDA, four strands of 3~0 silk \vere placed contrast medium was injected, six under the PDA, carefully avoiding the left radiographs were taken with a rapid cassette recurrent laryngeal nerve. Immediately after changer at an exposure rate of two per closure of the first strand of silk, the aortic second. After initial rapid accumulation of pressure rose abruptly to 150/110 and the the contrast in the left ventricle, a marked heart rate dropped from 110 to 50 beats per reflux was noted into the left atrium. This minute (Fig. 3). After the remaining three regurgitation was indicative of mitral in­ strands were securely ligated, a Foley catheter sufficiency. The left atrium and left ventricle was placed in the chest for post-operative were markedly dilated. At the level of the drainage. The nerves were released and the aortic aneurysm the PDA was identified and lung lobes were returned to their normal estimated to be ~ em. in diameter (Fig. 2). positions and inflated. The thoracotomy With passage of the contrast medium across incision was closed routinely. Before the the PDA, the main pulmonary artery was seen aortic catheter was removed, about 60 to be markedly dilated, with the pulmonary minutes after the PDA ligation, the pressure segment being approximately twice the size of had dropped to 100/80 mm Hg and the pulse the aorta. pressure was 20 mm Hg. 1

50 .Iowa State Unz"versz"ty Veterz"narz"an Postsurgical auscultation of the heart Since PDA is the mest common congenital revealed a slight systolic murmur over the heart disease seen in young dogs, its potential mitral valve. It was felt that this would presence should not be overlooked. In most disappear with time as the left atrio­ cases it is surgically treatable with a high ventricular annulus reduced in size. The degree of success. More importantly it Foley catheter was removed 12 hours post­ guarantees the affected dog a chance of a full operatively, having removed 50 cc. of fluid life span. Since surgical correction is feasible over this time. The dog was given a good in many cardiovascular cases, case referrals to prognosis for a normal life span. ISU are requested. When such cases arise Dr. D. H. Riedesel or Dr. D. W. DeYoung can be Conclusion contacted at (515) 294-4900.

The necessity for a thorough presurgical Bibliography physical examination was particularly em­ phasized in this case. Physical examination, 1. Archibald, J.: Canine Surgery. 2nd ed. American Veterinary Publications, Santa Barbara, California. combined with radiography and elec­ 1974. trocardiography, is usually sufficient to 2. Ettinger, S. j., and Suter, P. F.: Canine Cardz·ology. confirm a PDA and establish its surgical W. B. Saunders Co., Philadelphia. 1970. 3. Eyster, G. E., et al.: Patent Ductus Arteriosus in the potential. Although angiocardiography is not Dog: Characteristics of Occurrence and Results of necessary to PDA diagnosis, it would be Surgery in 100 Consecutive Cases. JA VMA 168:435-438. 1976. necessary to diagnose non-clinical cases, those 4. Patterson, D. F.: Advances in Veterinary Science and without machinery murmurs or with partial Comparative Medicine. Vol. 21. Cardiovascular closing (ductus diverticulum). Angiocar­ Pathophysiology. Academic Press. p. 3-9. 1977. 5. Weirich, W. E., Blevins, W. E. and Reborn, A. H.: diography can also be useful in determining Late Consequences of Patent Ductus Arteriosus in the associated congenital or secondary effects of a Dog: A Report ofSix Cases. J. A mer. An. Hosp. Assn. PDA, such as mitral insufficiency. 14:40-51. 1978.

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