Open heart surgery for a left atrial mass extraction during cardio-pulmonary bypass (CPB) in a 9 yoa Labrador dog

ranko

Dr Ranko Georgiev

Ranko Georgiev1, Stoyan Nikolov2, Nadezhda Petrova3

Georgi Ignatov4, MD Thoracic Surgery

1,2,3 DVM, Central Veterinary Clinic, Sofia, Bulgaria

4 MD, City Clinic Cardiovascular Center, Sofia, Bulgaria

1rankoge@gmail.com

 

Introduction:

 

Open heart surgery during a cardiopulmonary bypass is the only effective approach for some diseases that require an access to the heart chambers or the great vessels; even when a temporary inflow occlusion is chosen as an alternative, only a very few “time restricted” procedures could be done on a beating heart. However, when considering an open heart surgery, the high risk of intra- and post- procedure complications often outweighs the benefits. In veterinary medicine the financial weight of such a procedure is also a limiting factor.

We would like to share a case where a temporary sinus arrest was induced during a cardiopulmonary bypass and a huge mass was successfully extracted from the left atrium of a dog with an open heart approach.

 

Case presentation:

 

Artur 1

This is the patient just before the surgery

Arthur is a 9 year old MC Labrador, trained like a guide dog for a blind person, admitted because of increasingly frequent exercise intolerance episodes during the past few months. Furthermore, the last week the patient was very weak and experienced several syncopal episodes. On a clinical presentation with the referring vet а tachycardia and dyspnea were noted and the patient was referred to us for a Cardiology consult.

On physical examination, the dog weighted 25 kg, with a history of a rapid body mass loss for the last couple of months. His “normal” weight has always been around 32 kg according to the owners. The body condition was poor (score 2/5) and the dog had a grade II/VI left sided apical soft diastolic heart murmur. Lung auscultation was unremarkable, but the respiratory rate (RR) was more than 50 breaths per minute.Artur VD

Artur LLR

 

 

 

 

 

 

 

 

 

 

The X-rays of the chest were highly suggestive for e left sided congestive heart failure and showed mild generalized cardiomegaly with a VHS of 11.5 with enlarged left atrium and left ventricle. The pulmonary veins were slightly larger than the pulmonary arteries; the lung parenchyma with diffuse interstitial pattern in the area of the hilus. The patient was already on Furosemide in a low dose – 2mg/kg twice a day for the last two weeks with no improvement of the clinical signs.

 

 

A transthoracic echocardiography was done with the patient in lateral recumbence through the right and left parasternal windows. A huge echogenic mass with irregular shape was observed in the area of the left atrium – attached to the intra atrial septum and prolapsing through the mitral valve during diastole towards the left ventricle. The mass was creating almost full diastolic obstruction of the valve, allowing only a tiny fraction of the blood in.Artur_Ochi_na_4_lapi_20161116113435_1139400 Artur_Ochi_na_4_lapi_20161116113435_1140250 Artur_Ochi_na_4_lapi_20161116113435_1147090 Artur_Ochi_na_4_lapi_20161116113435_1837270 Artur_Ochi_na_4_lapi_20161116113435_1837510

Complete blood count, electrolytes and biochemical profile were normal. During the abdominal US study no further abnormalities were noted and no more masses found. On the ambulatory ECG a normal sinus rhythm was recorded with multiple atrial premature complexes. The blood pressure was normal. A hemo-culture and a urine culture were obtained and came back negative for a bacterial growth. The bleeding time and the Pt/APtT were normal.

A diagnosis of an intra atrial mass with clinical signs of a progressing left sided congestive heart failure was made and a surgery was discussed. Because of the location of the mass no surgical or interventional approach was possible without the aid of a cardiopulmonary bypass (CPB) and cardioplegia. All the risks and possible complications were discussed with the owner and a decision for such a surgery was made. The team for the surgery was from a veterinary surgeon, human cardiovascular surgeon, cardiovascular perfusionist, veterinary and human anesthetists, and nurses. The procedure was done in Central Vet Clinic, Sofia on 3rd of December 2016.

 

 

 

Artur 3

The heart-lung machine with 4 pumps – one main pump for the oxygenator and the blood, two for collecting the surgical field blood and one for the cardioplegique solution; the model is Sorin 5 with a pediatric small volume oxygenator

Our anesthesia protocol with this patient started routinely for the procedure of a thoracic surgery – premedication with Midazolam and Buprenorphine, induction with Etomidate, intubation and maintenance with Isoflurane. Additionally we put a bladder catheter for urine production measurement, central venous catheter, an intra-arterial catheter for a direct blood pressure measurement and tree peripheral intra-venous catheters. Many more drugs were used during the anesthesia and the long post-operative recovery period like Nitroglycerin, Atracurium, Protamine, Amantadine, Pyracetam, Efedrin, Dopamine, Methylprednisolone, Fraxiparin, Clopidogrel, antibiotics, etc.)

Artur 2

The busy surgical field – left lateral thoracotomy through the 5th intercostal space; visible are the venous, the arterial and the cardioplegique cannulae

Artur 7

the surgical ward during the procedure – a total of 10 people were simultaneously engaged in the procedure

Artur 5

the surgical ward during the procedure – a total of 10 people were simultaneously engaged in the procedure

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Artur 6

he extracted mass from the left atrium – Neurofibrosarcoma with size 8/6/4 cm

The surgical approach was through the left fifth intercostal space with a standard lateral thoracotomy. Additionally the left carotid artery was approached and prepared in case it is needed for the CPB blood return. The pericardium was excised and the left atrium, the big vessels and the left ventricle visualized. Then three cannulas were put – the one collecting the venous blood inside the right atrium (through the right atrium auricle), the one returning the oxygenated blood from the CPB machine into the ascending aorta and one small cardioplegique cannula into the aortic root over the coronary arteries. Then a bolus of Heparin was injected iv in a dose of 800UI/kg and 5 minutes later the patient was switched to the heart-lung machine (Sorin 5 and a pediatric oxygenator with 360 ml prime). Then we started a controlled cooling of the patient using a chiller, connected to the CPB machine. When the target body temperature of 28o C was reached the ascending aorta was cross clamped and a 600 ml of cooled to 4o C crystalloid cardioplegique infusion rich in potassium was infused through the coronary cannula producing complete heart arrest. We stopped the active ventilation of the lungs and the patient became fully dependent of the heart-lung machine. The heart was open through a 5 cm cut into the left atrial wall starting from the auricle tip. The mass was directly visualized and excised. It was connected to the intra atrial septum with a relatively small neck. We removed it without creating an ASD. The air from the heart was evacuated and the surgical cut closed with a 5-0 Polypropylene suture in a continuous way. The mass was a solid and well defined structure with irregular shape and was admitted for histology. The size was 8/6/4 cm.

We started a slow rewarming of the patient with a target body temperature of 38o C. Two epicardial electrodes were embedded and connected with an external pacemaker. Once closed and warmed, the heart was gently massaged manually for a couple of minutes and then hit with a direct pediatric defibrillator. We used 5 to 20J of energy shocks and got a slow and then faster rhythm after the 9th try. The external pacemaker was switched on and put on a 100 bpm rate for the next 12 hours. The surgical closure was uncomplicated and no significant bleeding was noted. The patient received slowly iv Protamin (1mg/100IU Heparin) as a Heparin antidote and the heart-lung machine was gradually restricted and then switched off. Two chest drains were put and connected to a sterile active suction. The total machine time was 130 min, the sinus arrest time – 22 min, total surgery time – close to 5 hours. Immediately after the CPB machine was stopped a hemotransfusion with two units of fresh blood was done.

Artur 10

the first 12 hours post the procedure Artur was kept on a Propofol CRI and with an external pacemaker set at a minimum of 100 bpm rate

Artur 9

the first 12 hours post the procedure Artur was kept on a Propofol CRI and with an external pacemaker set at a minimum of 100 bpm rate

Comments:

 

Arthur recovered from the general anesthesia slowly over the next 12 hours, but he was unable to stand on his feet for additional 5 days. The electrolyte levels, liver and kidney values were monitored almost every hour for the first 2 days and then three to five times a day; our main concern was the potassium blood level and we tried to maintain it stable at all times. The urine production was also constantly monitored and tailored to be in the normal range – with diuretics and blood pressure control drugs. From all the possible complications after a CPB we saw only a transient neurological signs attributed to some degree of brain injury – interpreted after the neurological exam as left sided forebrain lesion – ischemic or hemorrhagic. Arthur recovered completely both physically and mentally for the next two weeks with a lot of supportive care and physiotherapy. On discharge from the clinic he was able again to do all the things a blind person guide dog is trained to do. The histology report was made in a referral laboratory in Germany – Laboklin, and after the immunohistochemistry stain came back as a Neurofibrosarcoma.ran 2 ran 3

 

 

 

 

 

 

Artur 11

Artur reacted very well when in children company and we use this to stimulate his mental state (the authors’ youngest daughter)

Conclusions:

 

Artur 12

two weeks after the surgery with the owner

CPB is a routine everyday procedure in the human hospitals, usually carrying a good to excellent prognosis and very low mortality rate. On the other hand in the veterinary medicine field is still an exotic and very risky one. Although very demanding both for the clinical team and the patient himself, the cardiopulmonary bypass is the only option for cardiac diseases requiring an open heart surgery. We believe that a close relationship between a human medicine cardio surgical team and a small animal hospital team could make this type of procedures safer and better recognized.

We have done regular monthly rechecks on the patient with echocardiography and X-rays since then and now six months later Arthur is doing great, no drugs or any supportive therapy needed. He gained back his usual weight and is working like a guide dog every day.

 

Rupture of the atrial septum in dog with degenerative mitral valve disease

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Dr Todor Kalinov

Dr Todor Kalinov

ZaraVet- city of Plovdiv, Bulgaria

Introduction

Degenerative mitral valve disease (DMVD) is the most common cardiologic disorder in canine population. It has been estimated to account for 75% to 80% of canine cardiac disease1. It is common in small breed dogs, but also can be encountered in large breeds like german shepherd and other . The disease characterizes with thickening and enlarging of the mitral leaflets, elongation of chrdae tendineae and mitral regurgitation. Histopathologic  features are expansion of extracellular matrix with glycosaminoglycans and proteoglycans; valvular interstitial cell alteration; and attenuation or loss of the collagen-laden fibrosa layer2. Because of the mitral regurgitation the usual course of this disorder represents volume overloud of the left atrium and left ventricle , eccentric hypertrophy of the left ventricle , dilation of the left atrium ,and  left sided congestive heart failure . Increased pressure in left atrium and pulmonary veins leads to pulmonary edema . Often complication is so called passive pulmonary hypertension , consequence of increased pressure in pulmonary veins. Really rare complication is left atrial rupture .

 

Case presentation

fig 1

Fig. 1

fig 3

Fig.3

fig 2

Fig.2

Richka is 12 years old mixed breed dog with history of DMVD , threated only with enalapril . She was admitted in our clinic for cardiologic examination, because recently increasing in coughing and exercise intolerance. During the examination she was tachypneic , normal mucous membrane color , alert and responsive .She had increased heart rate. Auscultation revealed right and left apex systolic heart murmurs. The abdomen was swollen with palpable fluid thrill. We have made echocardiographic examination, with the patient on left and right lateral recumbency, with all parasternal views according to the accepted standards. We found eccentric hypertrophy of the left and right ventricles, left and right atrial dilation, thickening and prolapse of the mitral valve. Doppler examination shows mitral and tricuspid regurgitation with pressure gradient of 162 mmHg and 62 mmHg respectively (figures 1,2,3) . Abdominal echography revealed ascites. So we diagnosed degenerative mitral valve disease with secondary pulmonary hypertension. We prescribed following: pimobendan – 0.25 mg/kg/bid , furozemid – 4.0 mg/kg/bid , spironolactone – 1.0 mg/kg bid enalapril – 0.5 mg/kg/bid , sildenafil – 1.0 mg/kg/tid.

Week later on control examination Richka was better, ascites resolved , mitral and tricuspid regurgitation was with gradient 125 mmHg and 43 mmHg respectively. So we decreased the dose of furosemide to 2.0 mg/kg/bid, and the other drugs were continued with the same doses.

fig 4

Fig 4

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Fig 5

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Fig 6

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Fig 7

fig 8

Fig 8

Several months later the owners noticed again swelling of the abdomen and the dog collapsed after exercise. When they came in the clinic Richka was tachypneic with cyanotic mucous membrane. On auscultation we have found 5/6 systolic murmur on the right haemithorax with palpable precordial thrill. Electrocardiography revealed sinus tachycardia – 156 bpm , with premature supraventricular and multifocal ventricular complexes (fig 4). We have made roentgenography in right lateral (fig 5) and dorsoventral (fig 6) position. There was generalized cardiomegaly with dilation of the pulmonary vessels. On echocardiographic examination we have found eccentric hypertrophy of the left and right ventricles, paradoxical motion of the ventricular septum (fig 7), mitral and tricuspid regurgitation with gradient – 118 mmHg and 42 mmHg respectively. Abdominal ultrasonography showed ascites with no collapse of the caudal vena cava with respiration (fig 8). Despite the medications and lower then before pulmonary pressure in this dog the signs of right heart failure were predominant. Because of that and the palpable precordial thrill on the right side we suggested right to left intracardiac shunt. The presence of ventricular septal rupture is less possible, so we decide to search for rupture of the atrial septum. On the right parasternal 4 chambers view modified for better visualization of the right and left atrium with atrial septum, we have found rupture of the septum in the region of the fossa ovalis with left to right shunt.

 

 

 

Video 1 and 2 are same loops with and without colour Doppler demonstrating the defect and shunt of the blood. In this region very often because of the echo dropout on 2d image can be seen a hole in the atrial septum. To be sure that this is a real defect we decided to make a bubble contrast study. We injected 10 ml of agitated saline in v.cephalica antebrachii thru i.v. catheter.  When there is right to left shunt the microbubbles are seen in left atrim, left ventricle or arterial circulation – usually the abdominal aorta. But in left to right shunt the goal of the bubble study is to notice contrast washout during right atrium passing of the bubbles. Video 3 and 4 show right parasternal short axis view of the base of the heart with cranial vena cava. We can see the entrance of the contrast and the following washout like a flame because of the left to right shunting of the blood.

 

 

In this situation sildenafil makes the pulmonary pressure lower and facilitate the shunt from high pressure left atrium to low pressure right atrium. So we decided to use pulmonary hypertension properly and make the dose of sildenafil lower – 1 mg/kg/24 h. with presumption that higher right ventricle and right atrium pressure will make the amount of the shunt lower. 72 hours after this change the ascites resolves and the condition of the dog became better. On the time of the written of the article Richka is about half year on this medications with sildenafil once per day and no changes in other medications and the only clinical sign is exercise intolerance.

 Discussion

Rupture of the atrial septum is really rare complication of mitral valve disease. Most commonly the rupture occurs in caudal weaker part of atrial wall. In a study of Buchanan JW from 30 dogs only in 4 was found rupture of the interatrial septum with signs of right heart failure3. In another study from the same investigator from 50 dogs 7 have acquired ASD4. The еtiology for rupture of the left atrium is uncleаr , but probably is related with the high pressure in the left and right atrium and the so called jet lesions from the mitral and tricuspid regurgitation. Usually the mitral regurgitation jet is toward lateral wall of the left atrium like in this case (video 5). Tricuspid regurgitation jet was directed to interatrial septum so probably contributed to rupture of the septum. The thin fossa ovalis is weak and suitable place for this kind of lesions. In human medicin rupture of the septum is reported after blunt chest trauma , most often accompanied with rupture of the tricuspid valves 5,6. The proposed reason is that compressivе force occurred during isovolumic contractiоn with maximally dilated ventricles and closed atrioventricular valves5. In humans  right ventriсle is right behind the sternum , and this predispоse it to injury. In those cаses when there is rupture of the tricuspid valve and massive regurgitation , the increased pressure in right atrium leads to rupture of the septum and right to left shunt. In canine patients with degenerative mitral valve disease after the rupture of caudal atrial wall and following haemopericardium the clinical signs are collapse and sudden death. After rupture of the atrial septum the predominant signs are of right heart failure. In this case the right atrium and ventricle serves as a low pressure “sink” for severely dilated left atrium.

There are several publications about echocardiographic diagnosis of acquired atrial septal defect and rupture of the atrial septum with haemopericardium3,4. The bubble contrast study has been validated in veterinary echocardiography for diagnosis of congenital and acquired intra and extra cardiac defect and shunt7,8. In this case we have demonstrated the usefulness of so called contras washout – result of bubbles free blood entering contrast rich compartment.

In conclusion in any dog with degenerative mitral valve disease and predominated signs of right heart failure we have to look echocardiographically for atrial septal rupture. More we scan , more we find , and more we learn.

 

Pacemaker implantation (PMI) as treatment for AVB III and very slow ventricular escape rhythm in a geriatric canine patient

2 д-р Ранко Георгиев

Dr Ranko Georgiev

Ranko Georgiev1, Hristina Shukerova2, Nadezhda Petrova3

1,2,3 DVM, Central Veterinary Clinic, Sofia, Bulgaria

Introduction:

Pacemaker implantation is the most effective treatment for ‘syncope and severe exercise intolerance’ – related arrhythmias; however when searching for the best clinical decision for some older dogs, the risk of anesthesia often outweighs the benefits. We would like to share a case where the old age was not a problem.

Case presentation:

Larry was a 17-year old MI mix breed dog admitted because of increasingly frequent exercise intolerance episodes during the past few months. Furthermore, the last week the patient was very week, unable to stand on his feet and with a depressed overall clinical status. On a clinical presentation with the referring vet а bradycardia was noted and the patient referred to us for a Cardiology consult.fig 1 Lari-Ro-LLR

During auscultation, a slow regular rhythm was detected with heart rate of 20 bpm classified as ventricular escape rhythm during the normal ECG. A 24hour Holter monitor revealed complete AV block (AVB III) throughout the study with an average rate of 31 bpm, occasional VE beats with some pairs, triplets and short runs; no pauses greater than 5 sec were noted. The slowest heart rate detected was 20 bpm.fig 3 echocardio

Complete blood count and biochemical profile were normal. Radiography and echocardiography revealed generalized cardiomegaly, with mild-to-moderate mitral and tricuspid regurgitation and decreased contractility. During the abdominal FAST study a small amount of free fluid was noted – defined as a transudate on diagnostic abdominocenthesis. Lari_20150811163929_1640560

A diagnosis of complete AV block with clinical signs of right sided congestive heart failure was made and pacemaker implantation was decided. A VVI, bipolar, passive lead was fluoroscopically placed, under anesthesia, through the right jugular vein into the right ventricle, where it was successfully lodged.Lari_20150814181226_1819550 The lead was connected to a generator, which was later fixed in the subcutaneous tissue dorsally to the cervical vertebrae. A temporary pacemaker was used when the dog developed asystole during the procedure. Recovery from the surgery was uneventful, with the pacemaker capturing normally. The pacing rate was set to 100 bpm. The system used was a ‘St Jude’ one.r1

Our anesthesia protocol with this patient was routine for the procedure of a PMI – premedication with Midazolam and Buprenorphine, induction with Etomidate, intubation and maintenance with Isoflurane. The post procedure treatment was only with Cefazolin iv for the next few days.fig 4 PMI-procedure-1fig 5 PMI-procedure-2

The use of a temporary lead and/or an external pacemaker is highly advisable in patients who are depended on their escape rhythm.

Comments:

Even though Larry recovered from the general anesthesia normally he was unable to stand on his feet for additional 5 days. He was bright, alert and responsive, with good appetite and normal consciousness, but with an impaired proprioception. We attributed this to the long period with severe bradycardia (HR of 20 bpm) and potential vasoconstriction/reperfusion complications. There is some data in the human medicine literature concerning PMI in old people with preexisting severe bradycardia, who reported pain in the extremities post the procedure.

Other factors such as chronic joint and spinal diseases could have been the cause of the slow recovery as well. The myoglobin levels were not checked prior to the PMI unfortunately.fig 6 flororfig 8 Lari-Ro-LLR-post-PMI

Conclusions:

Pacemaker implantation may be warranted even in older dogs with ‘syncope and severe exercise intolerance’ – related arrhythmias.r2

7 months post the procedure Larry is still doing great; in this period he underwent two additional major surgeries for a prostate abscess – with no anesthesia complications.581708_10201218994737586_1026692492_n