Briefing Document: {patient1}- Patent Ductus Arteriosus (PDA)
Date: October 26, 2023
Patient: {patient1}, a 4-month-old, 1.85kg male Yorkshire Terrier
Presenting Problem & History:
- {patient1} was referred for evaluation of a heart murmur detected at the referring veterinary clinic. Two different vets at the clinic couldn’t definitively determine if a murmur was present.
- Owner reports normal energy and appetite at home. No coughing or fainting episodes (syncope).
- No other significant non-cardiac medical history.
- Recent diet change from Blue Buffalo to Hill’s kibble, mixed with Fresh Pet and home-cooked vegetables.
- No recent bloodwork or radiographs at the referring vet.
Key Findings from Examinations & Diagnostics:
- Initial Physical Exam: A heart murmur was auscultated and the rhythm was noted, femoral pulses were strong and synchronous, CRT <2s, MM moist and pink, Respiratory status: Eupneic, No crackles or wheezes. Abdomen soft, non-painful.
- Echocardiogram: The results revealed:
- Severe eccentric hypertrophy of the left ventricle due to volume overload.
- Moderate systolic dysfunction.
- Moderately enlarged left atrium.
- Severely dilated main pulmonary artery and its branches.
- Prolapse of the pulmonary valve cusps.
- Mild mitral regurgitation (blood leaking backward through the mitral valve).
- No tricuspid regurgitation.
- Crucially, a continuous flow through a patent ductus arteriosus (PDA) was identified. The jet originated proximal to the bifurcation of the pulmonary artery and was directed towards the pulmonary valve, with a maximal velocity of 4.8 m/s (90 mmHg) and minimal ductal diameter of 1.6 mm.
- Key Measurements include:
- IVSd (Interventricular Septal thickness in diastole): 3.6mm
- LVIDd (Left Ventricular Internal Diameter in diastole): 26.4mm
- LVFWd (Left Ventricular Free Wall thickness in diastole): 4.5 mm
- LVIDs (Left Ventricular Internal Diameter in systole): 19.1mm
- Fractional Shortening (FS): 27.6%
- Left Atrium (LA): 19.7 mm
- Aorta (Ao): 11.0mm
- LA/Ao ratio: 1.79
- AV Vmax (Aortic Valve Maximum Velocity): 1.6m/s
- PV Vmax (Pulmonic Valve Maximum Velocity): 1.8m/s
- Radiographs: No overt evidence of congestive heart failure was seen, but given the degree of left-sided overload, {patient1} was considered at high risk for developing congestive heart failure.
Diagnosis:
- Patent Ductus Arteriosus (PDA): Patent Ductus Arteriosus (PDA) is one of the most common congenital cardiac disorders diagnosed in the dog. It is characterized by persistence of the ductus arteriosus (DA) which is the fetal communication which exists between the aorta and the main pulmonary artery… Due to the higher pressures in the aorta, oxygenated blood will shunt across the DA into the pulmonary artery. This recirculation circuit results in an overload of blood flow to the lungs, left atrium, and left ventricle.
- {patient1}’s PDA is causing significant left ventricular volume overload and is putting him at high risk for congestive heart failure.
Treatment Plan:
- Medication: Vetmedin (pimobendan) 0.625mg by mouth twice daily was prescribed.
- Procedure: PDA ligation to be scheduled with surgery ASAP. The preferred treatment is closure of the ductus, ideally via a catheter-based procedure using an ACDO device. However, due to {patient1}’s small size, surgical ligation via thoracotomy (opening the chest) is likely necessary.
- Monitoring: Sleeping respiratory rate monitoring was recommended. A normal sleeping respiratory rate is <30 breaths per minute. Rates of 40-50 breaths/minute suggest early congestive heart failure, and rates >50 breaths/minute may require emergency intervention.
- Sleeping respiratory rates >50 breaths per minute, increased respiratory effort, or increased effort may indicate an emergency requiring medical intervention/hospitalization.
- Follow up: Recheck following surgical ligation.
Prognosis:
- Once the ductus is closed, long term prognosis is excellent. Therefore, once the PDA is addressed {patient1} has a great prognosis.
Key Takeaways:
- {patient1} has a confirmed PDA, a congenital heart defect requiring surgical correction.
- His condition is causing significant changes to his heart, including left ventricular hypertrophy, left atrial enlargement, and volume overload.
- Despite being asymptomatic currently, he is at high risk for congestive heart failure.
- Surgery to close the PDA is the recommended treatment.
- Post-surgery, {patient1}’s long-term prognosis is considered excellent.
