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Friday, November 18, 2011

ANAESTHESIA AND HYPERTROPHIC OBSTRUCTIVE CARDIOMYOPATHY HOCM

Recently I had a case of 70yr old HOCM with prolonged QT on ECG echo shows septal Hypertrophy with LVOT gradient of 10 mmHg,Heart rate 63/min and BP 140/80 mmHg,Otherwise fit and healthy, no h/o Exertional Angina, Exertional Syncope or Exertional breathlesness.

Posted for a Rectopexy/laparoscopy, likely 1.5 hours on an elective evening list.

No regular medications.Previously seen by Cardiology had a General Anaesthetic 3 years back without any problems.


I had to seek a few answers to my Questions.

Is this Echo predictive of intraoperative situation?

Is laparoscopy with head down position safe?

How do I know the severity of the situation?

How should I maintain the Haemodynamics?

What Monitroing other than Spo2 Etco2 NIBP Gas conc. ?

The relevance of Prolonged QT and Anaesthesia?


HCM can be considered obstructive or nonobstructive, depending on the presence of a left ventricular outflow tract (LVOT) gradient, either at rest or with provocative maneuvers. Since its a Dynamic obstruction,unless you put the patient through a

stress test which simulate intraop/postop conditions, you may not have much information.

Keeping the heart dilated and distended helps and a head down position would have been ok,The laparoscopic pressures were kept low around 12 mmHg.The peak airway pressures were kept around 22 cm H2O with a peep of 5 cm H2O to achieve a reasonable CO 2 clearance.


The severity could be related to the peak gradient of LVOT, Mitral regurgitation, left atrial size,

also h/o Exertional Angina, Exertional Syncope or Exertional breathlesness (like in Aortic stenosis)

Sudden Cardiac deaths are more likely in Young patients. They will not tolerate arrhythmias.


ON ECHO

1. Left atrial dilatation. the presence of a left atrial index > 25 mm/mm and a left atrial diameter > 45 mm were predictive of mortality .

2. Left ventricular hypertrophy. sudden death rate could increase progressively in direct relation to the maximum left ventricular wall thickness, mostly when thickness is >20 mm .

3. Left ventricular dilatation. patients who develop ventricular dilatation have a high rate of complications and a lower survival .

4. Left ventricular systolic dysfunction. Decrease of the left ventricular systolic shortening below

35% is predictive of heart failure, which is usually associated with the left ventricular dilatation .

5. Severity of dynamic gradient. left intraventricular gradient > 30 mmHg has an unfavourable prognosis, gradient > 50 mmHg was a predictor of higher mortality rate.

6. Severity of mitral regurgitation. There is a correlation between the severity of the gradient and

mitral regurgitation in patients with HOCM


Haemodynamic goals were to go Slow, full and tight .

This dynamic obstruction could be worsened by increased Heart rate,Increased contractility and poor filling.

It was well achieved with good preloading with 1 litre Hartmanns before induction,Slower Heart rate with Alfentanil 1000mcg as co induction agent and early Morphine 3mg IV and early use of 0.5 mg metaraminol bolus with slow Propofol 200mg IV induction and later steady metaraminol infusion.

Monitoring, I added a Radial arterial Invasive BP monitoring.

REFERENCE
 1.:http://www.annals.in/article.asp?issn=0971-9784;year=2010;volume=13;issue=3;spage=253;epage=256;aulast=Sahoo
2.http://medind.nic.in/iad/t07/i2/iadt07i2p134.pdf

VIDEO :

Prolonged QT, Resucitation trolley was checked and avoided Ondansetron, ensured magnesium is available.

Used Propofol, Thiopental prolongs the QTc 
succinylcholine Avoided used Atracurium
Avoided Atropine / Glycopyrrolate which prolong the QT interval
reversal of neuromuscular block in known LQTS patients is probably best avoided whenever possible.
Refer:http://bja.oxfordjournals.org/content/90/3/349.full