General: Infective Endocarditis

Decision making re: surgery and its timing in acute infective endocarditis:

References:
1) Eur J Cardiothorac Surg 2009;35:130-5. Hickey EJ, et al. (Toronto group)
Authors report surgical experience of 30 children operated for endocarditis in the past 30 years (1978-2007). Strep. viridans was noted predominantly with known cardiac defects. Staph. aureus was associated with abscess formation, clinical sepsis, acute deterioration and death. Aortic, mitral and tricuspid valves were involved with equal frequency. Pulmonary valve involvement was rare. Native valve was preserved in 22 children (73%). Univariate predictors of valve replacement were increased valve thickening and septic emboli (Severity of valve regurgitation was not predictive). Good paper.

2) Circulation 2010;121:1005-13. Lalani T, et al. Analysis of impact of early Surgery on in-hospital mortality of native valve endocarditis.
Data from an international registry. Non-randomized, retrospective study. So, of limited help. But, still useful information from a large cohort. Conclusion is that early surgery for native valve endocarditis has benefit of lower mortality compared to medical therapy alone. (Defn. of early surgery is replacement or repair of valve during initial hospitalization for IE).
...Read als0, the editorial on this article at Circulation 2010;121:960-2.

3) European guidelines for prevention, diagnosis and treatment of infective endocarditis. Quite useful. Eur Heart J 2009;30:2369-2413.

4) American Heart Association Guidelines:
(i) ACC/AHA 2008 Guideline Update on Valvar Heart Disease: Focus on infective endocarditis. Circulation 2008;118:887-896.
(ii) ACC/AHA 2005 Guideline: "Infective Endocarditis: Diagnosis, Antimicrobial therapy and management of complications" Circulation 2005;111:3167-3184. Or, the full text version (44 pages long) from AHA website.

Surgery: Konno, Ross-Konno

Konno Procedure:

(Figure from Kirklin/Barrat-Boyes Cardiac Surgery 3rd Ed. p1292)

Ross-Konno Procedure:

(From Mavroudis & Backer Pediatric Cardiac Surgery 3rd Ed.)


Classic Konno-Rastan Procedure:

(From Mavroudis & Backer Pediatric Cardiac Surgery 3rd Ed.)
Modified Konno-Rastan Procedure:

(From Mavroudis & Backer Pediatric Cardiac Surgery 3rd Ed.)

Methods to enlarge aortic annulus: (Antionio F. Corno "Congenital Heart Defects - Decision making for surgery" Vol.1)

1) Posterior annular enlargement:

Nicks - aortotomy extended through non-coronary sinus and anterior mitral leaflet (prosthetic patch).

2) Managouian - aortotomy extended through left and non-coronary sinuses and anterior mitral leaflet (prosthetic patch).

Aortic Valve sparing:

Jonas modification to preserve aortic valve annulus - for tunnel-type SubAS and mitral stenosis (needing enlargement of mitral annulus), but aortic valve annulus is adequate - aortotomy extended via commissure between NCC & LCC and extend the incision across mitral annulus to roof of LA. Replace mitral valve with prosthesis and a triangular patch to enlarge mitral annulus and close LA incision. Aorta is closed preserving aortic valve annulus. (Jonas RA et al. JTCVS 1998;115:1219)

Surgery: AVSD Repair Patch Types

(From Mavroudis & Backer's book)

3 different patch techniques used in AVSD repair:A: Single Patch Technique - commonly used. B: Two Patch Technique
Trusler GA. JTCVS 71:296,1976
C: Modified Single Patch Technique (Australian or Nunn technique)
Nunn GR. Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu. 2007:28-31.


VSD sutures go on the rightside of the crest of septum to avoid LBB and AV node - as shown below:

TAPVR, Supracardiac - Locations of Obstruction

And, at the interatrial septal level. Image from Moss and Adams Fifth Edition 1995.

Quotes: Atul Gawande

Five rules for the class of 2005:

1) Ask an unscripted question

2) Don't whine

3) Count something

4) Write something

5) Change,

...To have a good life in medicine

http://www.leighbureau.com/speakers/AGawande/essays/Harvard.pdf

Physician Autonomy: (Excerpt from "The checklist manifesto - How to get things right" Atul Gawande. Metropolitan books 2009)

p 65: ...the medical way of dealing with extreme complexity - with inevitable nuances of an individual patient case - is to leave them to the expert's individual judgement. You give the specialist autonomy. In this instance, Rouillard was the specialist. Had the building site been a hospital ward, his personal judgement would hold sway.

This approach has a flaw, however, O'Sullivan pointed out. Like a patient, a building involves multiple specialists - the sixteen trades. In the absence of a true Master Builder - a supreme all-knowing expert with command of all existing knowledge - autonomy is a disaster. It produces only a cacophony of incompatible decisions and overlooked errors. You get a building that doesn't stand up straight. This sounded to me like medicine at its worst....

p67: ...Man is fallible, but may be men are less so...

EKG: "Crochetage" & Incomplete RBBB in ASD

"Crochetage" (Notch) on R wave in inferior limb leads: A new independent electrocardiographic sign of atrial septal defect. Heller J, et al. JACC 1996;27:877-882

Extract from above article:

"Crochetage" is a notch near the apex of R wave in inferior limb leads.

First reported in 1959 in 11 pts. with ASD. Mechanism of production of this crochetage is not known.

1) Crochetage is independent of Incomplete RBBB (iRBBB) seen in V1 for the following reasons:

(i) Crochetage may be present without iRBBB pattern

(ii) Crochetage disappears in immediate postoperative period while iRBBB - which is due to chronic RV volume overload persists longer

(iii) Crochetage always involves the first 80 ms of R wave, while iRBBB involves the last part of R wave.

Examples from 2 patients:Disappearance of "crochetage" 3 days after surgery for ASD:Crochetage is not unique to ASD...and is noted in normal children too!

But, it is highly specific (92-100%) for ASD and for other conditions:

For ASDs, crochetage is not any more sensitive than iRBBB.

EKG: Epsilon Wave

ECG recording: (a) post-excitation epsilon wave (arrows) in right precordial leads; (b) positive late potentials at signal-averaged electrocardiography (SAECG).
Thiene et al. Orphanet Journal of Rare Diseases 2007 2:45 doi:10.1186/1750-1172-2-45

http://www.ojrd.com/content/2/1/45/figure/F5?highres=y

Exercise Testing: Some terminology clarified

Anerobic Threshold: Time at which the patient starts to exhale increasing amounts of carbon dioxide (VEco2) to compensate for a build up of lactic acid and resulting metabolic acidosis.





At AT, lactate starts to accumulate. Since it is a weak base, it readily dissociates releasing H+ ions. These H+ ions are bufferred by bicarbonate system. This generates extra CO2. This results in increased rate of release of CO2 (VEco2) without a concomittant increase in oxygen consumption (Vo2).


At this point, there is hyperventilation relative to Vo2, but not relative to Vco2. This is Anerobic Threshold.


If the exercise continues, pH falls. Lower pH stimulates cardotid bodies leading to hyperventilation

ICU/EKG: Hypothermia & EKG changes ...Osborn Wave

(Extract from "Principles of Clinical Electrocardiography". Mervin J. Goldman. 11th ed. 1982 p. 291)

Hypothermia induces EKG changes:

1) Sinus bradycardia

2) Junctional rhythm

3) Prolongation of QTc

With extreme degrees of cooling,...

1) Intraventricular conduction delay - causing notching of terminal portion of QRS (Osborn wave) followed by ST elevation

2) ST elevation

3) V. fib (when rectal temp falls below 28 degree C.

Other references:

1) Kelly FE, Nolan JP. The effects of mild induced hypothermia on the myocardium: A systematic review. Anesthesia 2010 Feb 11 [Epub ahead of print]

2) Fink EL, Kochanek PM, Clark RS, Bell MJ. How I cool children in neurocritical care. Neurocrit care 2010 Feb 10 [Epub ahead of print]

3) Khan JN, Prasad N, Glancy JM. QTc prolongation during therapeutic hypothermia: are we giving it the attention it deserves? Europace 2010 Feb;12:266-70. [Epub 2009 Nov 30]

4) Fink EL, Clark RS, Kochanek PM, Bell MJ, Watson RS. A tertiary care center's experience with therapeutic hypothermia after pediatric cardiac arrest. Pediatr Crit Care Med 2010 Jan;11:66-74.

5) Tiainen M, Parikka HA, Makijarvi MA, Takkunen OS, Sarna SJ, Roine RO. Arrhythmias and heart rate variability during and after therapeutic hypothermia for cardiac arrest. Crit Care Med 2009 Feb;37:403-9

Anatomy: AVSD - Rastelli Types

Rastelli Type A

Rastelli Type B

Rastelli Type C
Images from Moss & Adams (Fifth Edition)