Haemodynamic clasification of VSD and lntra cardiac shunt

Haemodynamic clasification of VSD and lntra cardiac shunt
Prof. Dr. Mohamed A.nasr MB;BCh;PhD;MD;FACS;FICS
Maitre es Sciences Medicales ( France)
Membre du College Francals de Chirurgle Thoraclque et Cardiovasculaire
Professor of Cardiac Surgery . National Heart Institute Egypt

intracardiac shunts are an important chapter in pediatric cardiac surgery. When should an intracardiac shunt be corrected. When should surgery be postponed and when should it be urgent?
This in fact depends on pulmonary blood flow. The lung is not done to withstand a high pulmonary flow. Pulmonary artery branches Inside the lung continue to divide until they become very small arteries having 1 mm. in diameter. The latter arteries present before alveoi constitute the pulmonary vascular bed.
In presence of a VSD as an example of an intra-cardiac shunt, blood pases from high pressure side to the low pressure side. It passes from the left ventricle to the right ventricle. A higher blood flow passes to the pulmonary artery and lungs. Such a high flow Induces destruction of the elastic fibers lining the snail lntrapulmonary blood vessels. Healing of destruction of the elastic fibers occurs by collagen fibers and not elastic fibers. First it heals by soft collagen fibers then by tough collagen fibers. Arteries loose their compliance. Thrombi develop inside the lumen of such small blood vessels. Later thrombi become organized. At such a step the pulmonary vascuar bed start to be obstructed and the pulmonary artery pressure increases. Arteries containing organized thrombi dilate.
They end by developing necroid degeneration.
The above path0 - physiological changes have been discovered by Heath and Edwards in 1958.
Once the pulmonary vascular bed is obstructed, the pulmonary artery pressure become higher than the systemic blood pressure.
Blood starts then to flow from the right ventricle to the left ventricle. A phenomenon known as Elsenmenger Syndrome.
The patient starts to develop cyanosls flrst on effort then on rest.
Closure of the intra-cardiac shuntat this state closes the security valve of the overstressed right ventricle. Patients do not come off bypass. The only treatment of Eisenmenger Syndrome is heart and lung transplantation.
In presence of any congenital heart anomaly, pediatric cardiology always avoids development of such reverse of the left to right shunt to a right to left shunt. if pulmonary flow is decreased by an associated pulmonary outflow tract obstruction, the patient is considered protected from Eisenmenger Syndrome and surgery may be postponed
until later age when open heart procedure may be easier.
in order to put such a phenomenon in a scientific form , French school established a hemodynamic classification of VSD that may be applied on all cases of lntra-cardiac shunt : Patent ductus arteriosis, ASD etc.
Haemodynamlc classification of VSD
Type ı Roger's Disease. Small VSD with no hemodynamic
Significant shunt
Type ıı a- Pulmonary artery pressure less than 70% Aortic pressure
b- Pulmonary artery pressure more than 70%
Aortic pressure
Type ııı Eisenmenger Syndrome has been esablished
Type ıV VSD + Pulmonary outflow tract obstruction
Type one: Surgery is not indicated. Prophylaxis against endocardltlis is indicated.
Type ıı (a) PAP may be 40 and AOP 100. There is clinically a well audible ejection systolic murmur on pulmonary area. There is a well felt thrill. At this stage surgery is indicated based on echocardlography without Catheterization
Type ıı(b) This a border line stage before Elsenmenger
Catheterlzation is indicated before surgery to calculate pulmonary vascular resistance (PVR) and its percentage to the systemic vascular resistance
PVR= PAP - wedge( left atrial pressure)
Flow
When PVR is less than 7 surgery is indicated . If PVR is between 7 and 10 recalculation is done by giving pure oxygen to the patient. Catheterization should not use ketamine that Increases PAP. If alter calculation PVR decreases below 7 Lung biopsy may be needed to verify pathology of the lung vasculature according to Heath Edwards anatomo-pathological dassification. 3 lung biopsies should be taken In three different areas of the lung . Each biopsy should be cut to give 4 areas. in fact sometimes Pathologist may discover an area that reveals inoperablilty and other areas that are reveals operablllty. it is beause of such a difficulty in diagnosis that lung biopsy is actually rarely done
Pediatric cardiologists rely on PVR/SVR it should be less than 0,5. If it is between 0,5 and 1 recalculation is done after giving the patient pure oxygen and lsoprenaline. if the ratio become 0,5 or less the defect is closed.
The above hemodynamic classification of the VSD as an example of any intra-cardiac shunt is practical and may be applied to evaluate time of operability of any case of congenital heart anomaly.
Anatomical classification of VSDs
The interventricular septum is embryo logically composed of three parts
1- An inlet part related to Tricuspid valve also called the membranous part . Any defect in this part is called inlet VSD or membranous VSD
2- An outlet part below the pulmonary artery . it Is also called the conus part. Any defect in this area is called outlet VSD
3- A muscular or trabecular part which is the main muscular part of the septum. Any defect at this area is called muscular VSD
4- If a defect is encroaching on two of the three parts it is called Malalignement VSD
Anatomical ciasflcation of the VSD dos not play a role in deciding time of surgery. it is the hernodynamic classification that is primordial in indictlng time of closure of the defect
Is the VSD in Tetralogy of Fallot a defect in the ventricular septum?
The answer is not. The VSD in the Tetralogy of Fallot is not a defect of the septum but deviation of the whole oonus anteriorly inducing overriding of aorta on the two ventricles. IN Tetralogy or Fallot the VSD is large because the whole conus has been deviated anteriorly during development
Conclusion: Anatomical classification of VSD is of the surgical domain while hemodynamic dassiflcation of intra-cardiac shunt Is an important chapter that interests surgeons , cardiologists pediatricians and all physicians.
Two other Curious Chapters In cardiology that deserves to be clarifies
Syndrome X
Cardiac Syndrome X is characterized by angina In patients with «normal» coronary arteries
Syndrome X is more common in women than In men
The underlying pathophysiology or Syndrome X is largely unknown, but is thought to involve microvascular dysfunction and abnormal pain perception.
Normal or nonobstructed coronary arteries are oommon in patients presenting with chest pain
Syndrome X patients usually present with symptoms similar to myocardial ischemia secondary to atherosclerotic CAD, but have normal coronary arteries upon anglography
The cause of Syndrome X in Individual patients is multlfactorial, and may involve endothelial and microvascular dysfunction, ischemia, and enhanced pain perception
Syndrome X is diagnosed by ruling out other cardiac and noncardiac causes of chest pain
Testing for endothelial dysfunction may provide prognostic value
Treatment of Syndrome X aims to eliminate angina and improve quality of life
Nitrates are effective In half of all Syndrome X patients; other therapy may include calcium channel antagonists, beta blockers, and analgesitcs
Hormone therapy can reduce the frequency of chest pain episodes in postmenopausal female Syndrome X patients
The magnitude of the effect of Syndrome X on survival is unclear
Endothelial dysfunction in patients with Syndrome X is a predictor of worse outcomes
Syndrome X is associated with an increased risk of major adverse
cardiac events, particularly repeat hospitalizations and catheterizatlons
Prinzmetal’s (Variant) Angina
Prinzmetal’s Angina is unstable angina caused by coronary artery spasm. It is a transmural myocardial ischaemia
Prinzmetal’s angina is rare, and more common in men than women; few gender-specific studies exist
The pathophysiology of coronary spasm is not well known
Angina usually occurs at rest during the early morning, and attacks often occur in clusters
Patients with Prinzmetal's Angina usually have atherosclerotic CAD
ST-segment elevation during rest angina in the absence of obstructive CAD is diagnostic of Prinzmetal's angina
Provocative testing is useful to induce spasm for ECG monitoring
Calcium antagonists are the first-line therapy for variant angina; in patients with obstructive CAD, treatment of the underlying CAD should be considered
Prognosis is good in patients with variant angina who receive medical therapy
Presence and extent of obstructive CAD are correlated with worse outcomes.