Post Mitral Valve replacement Ventricular fibrillation (case Discussion )

shenxiu2

63 years old lady . weight =38kg, height =155cm.

Diagnosis:   Rheumatic heart Disease with severe mitral stenosis ( MVA=0.55cm2), mild to moderate mitral regurgitation. Severe Pulmonary Hypertention ( PAP=104mmHg) . Posted for Mitral Valve replacement ( Mechanical valve).

History:  Diabetes Mellitus , good control.
Post thyroidectomy 10 years ago, hypothyroidism on L-thyroxine 0.1mg daily.
Her effort tolerance : can climb  one flight staircase.
No orthopnoea , has occasional paroxysmal nocturnal dyspnoea.
On oral medications: Atenolol,frusemide,potassium supplement , L-thyroxine,warfarin ( stopped 5 days)

Examination: Blood Pressure =143/51mmHg, heart rate =50/min, pulse irregularly irregular.
Lungs clear.

Investigations:
Haemoglobin=14.3g%
platelet count =251,000
Renal function test normal
Serum T4=normal
Prothrombin time / APTT normal.
ECG=Slow Atrial fibrillation ..
Chest X-ray =Cardiomegaly. Lungs appeared normal .
Echo=grossly dilated  Left Atrium, moderately dilated right ventricle & right atrium. EF=64%.Severe mitral stenosis ( MVA=0.55cm2), mild to moderate mitral regurgitation. Severe Pulmonary Hypertention ( PAP=104mmHg) .
Coronary Angiogram =mild LAD 40% stenosis.

Intraoperative:

0830:  Induction of anaesthesia---IV Fentenyl 200mcg+ midazolam 3mg + rocuronium 70mg.  Maintained with sevoflurane 1-3.5%.
0855:  Surgery started . ---added  IV Fentanyl 200mcg +midazolam 2mg . Baseline ACT=119 seconds.
0905:   Heparin 115,000 units given . ACT>550sec.
0925:  On cardiopulmonary bypass.
10.00 : Rewarming . Started IV Milrinone infusion 0.375mcg/kg/minute.
1025:  Attempted synchronized cardioversion 10 Joules X 2 , not successful , remained Atrial Fibrillation. Started on demand ventricular pacing ,rate at 80/minute.
1030: Off Bypass . reverse heparin with protamine. ACT = 130 sec. Chest Closure .
1100: Out to ICU .

Post operative - in ICU:

1700: Patient fully awake. obeying commands. moving 4 limbs. Extubated.
1845 : Developed sudden ventricular fibrillation . CPR ,defibrillation. reintubated. 1mg Adrenaline given .
1900: Pulse recovered  . On ventilatory support . BP=130/60mmHg. HR=80/min( pacing rate ) , own rate=50-60/min ( slow AF).

Arterial Blood Gases  (IN ICU ):

1117:  ( Immediately Post Operative)
pH =7.46,pCO2=30,pO2=312,BE=-1,HCO3=21,SPO2 =99% Ca+=1.14,K+=3.9,Na+=146,Glucose=9.3 mmol,Hematocrit=31%, hemoglobin=11g%.

1722:( After extubation ) pH=7.5,pCO2=29,pO2=188,BE=0.4,HCO3=22,SPO2=98%,Ca+=1.07,K+=3.2,Na+=147,glu=7.8,Hb=12.5g%,Hct=36%

1844(Just before patient collapsed)
pH=7.4,pCO2=37,pO2=115,BE-0.7,HCO2=24.6,SPO2=99%,Ca+=1.1,K+=3.2,Na=+149,glu=6.1,Hb=12.5%,Hct=35.2%

1930: ( After resuscitation )
pH=7.36,pCO2=28,pO2=582,BE= -8.6,HCO3=15.5, SpO2=100%,Ca+=1.07,K+=2.9,Na+=149  

Questions:
1.What could be the cause of the ventricular Fibrillation post operatively in this case?
2. How should this patient be managed after successful  resuscitation?

cqxdeer88

很好病例
认得个大概
英文快丢光了

还望不吝赐教啊。----参宿2

心超

I want to asking about  the heart rate before the patient collapes.

1) Arterial blood gas was normal just before  VT, that means the reasons of  VT Should not be electrolyte associated.

2)One or two ventricle over preloading?

3)how about the tricuspid regrugetation?

shenxiu2

I want to asking about  the heart rate before the patient collapes.

1) Arterial blood gas was normal just before  VT, that means the reasons of  VT Should not be electrolyte associated.

2)One or ...
心超 发表于 2010-1-16 18:13

                               
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The patient 's heart rate was on ventricular  pacing, rate at 80/minute.  Without pacing , her own  rate was about 45-55/minute, in slow atrial fibrillation.
Central venous pressure was 9mmHg before collapse. There was no PA floatation catheter inserted.

shenxiu2

Progress of the patient:

Post resuscitation,she was sedated & paralysed for 24hours, with IV Midazolam 0.5mg/hour +morphine0.5mg/hour + atracurium 15mg/hour infusion. Ventilator settings were set  to maintain PCO2 at 30-35mmHg, PO2 >100mmHg, no dextrose / glucose infusion  for 24 hours,
After 24 hours, sedation & paralysis medications were  off, She resumed spontaneous breathing , but did not regain consciousness. She manifested signs of hypoxic encephalopathy ( twitching of muscles , eyelids, jerky movements of the body , occasional eye opening, no meaningful movements of 4 limbs, do not obey commands, do not recognize people ). CT brain was normal .

1.How do you manage the patient now?
2. What is the prognosis?

心超

5# shenxiu2


Mortality among patients after cardiac arrest is high.  standardised post resuscitation protocol focusing on vital organ function including therapeutic hypothermia, percutaneous coronary intervention (PCI), control of haemodynamics, blood glucose, ventilation and seizures。this patiet will take a very long time regain consciousness.

shenxiu2

6# 心超

We had given up hope that this patient would  recover at all. Even the neurologist informed the relatives that she will need long term care in this coma state.  
But miracles happen everyday! After 3 days , she woke up . Now she is fully conscious, obeys commands, can speak rationally. The only neurological deficit she has is some weakness of the limbs.

All the ICU nurses & the doctors rejoice over this patient's  recovery .

We are still puzzled as to what could be the cause of the ventricular fibrillation.  
One postulation is that the ventricular pacing was not set at full "demand mode", so there was occasion when the pacing was not  synchronized with the patient's cardiac impulse  , then the phenomenon of "R on T" happened , which triggered the ventricular fibrillation.