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extends to the membranous septum.

The 4 parts of the ventricular septum are as follows:

1. the inlet septum is smooth walled and extends from the septalattachments of the tricuspid valve to the distal attachments of thetricuspid tensor apparatus. This region has also been called the AVcanal septum.4

2. The apical trabecular zone separates the coarse trabeculations of theRV from the fine ones seen in the left ventricle (LV). Van Praagh et alrefer to this as the muscular septum or the ventricular sinus septum.4

3. The smooth-walled outlet or infundibular septum is separated from thetrabeculated portion of the RV by the septal band of the trabeculamarginalis. Van Praagh et al called this area the parietal band or thedistal conal septum and refer to defects in this area as conal septaldefects.4

4. The last and the smallest region in the ventricular septum is themembranous septum. This lies between the anterior and the septal

tricuspid leaflets and below the right and the noncoronary cusps of theaortic valve.o The 3 muscular components of the ventricular septum described

above abut on the membranous septum and fan out from it astriangles, with the apices touching this septum. In the normalheart, the tricuspid and mitral valves are attached to theventricular septum at different levels so that the tricuspid-valveattachment is apically displaced compared with the mitral-valveattachment. Therefore, a portion of the interventricular septum,called the AV septum, lies between the right atrium (RA) and theLV. This portion consists of a membranous part anteriorly and amuscular part posteriorly and is usually present in most hearts

with an isolated ventricular septal defect.o In the anterior aspect, the tricuspid-valve attachment divides the

area of membranous septum into an interventricular component(between the LV and RV) and an AV component (between theLV and RA). When a ventricular septal defect is isolated, the AVcomponent of membranous septum is usually intact.

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Anatomy&Types

Ventricular septal defects (VSDs) are classified by the position theyoccupy in the ventricular septum.

The septum is divided into 4 components:

1-the membranous septum,

2-the inlet.

3-the trabecular.

4- the outlet parts of the muscular septum.

(The outlet septum is also called the conal or infundibular septum.)

Thus, 4 anatomic types of VSDs exist.

Type I defects(subarterial-conal-outlet):

*are also known as: subarterial, outlet, or conal defects.

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1-perimembranous inlet

2- perimembranous trabecular

3- perimembranous outlet.

Type III defects (atrioventricular canal-AV septal-inlet septal):

*also called atrioventricular (AV) canal, AV septal, or inlet septal defects,

*(10% of all VSDs).

* are located in the posterior region of the septum beneath the septalleaflet of the tricuspid valve.

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HEMODYNAMICS

The physical size of the VSD is a major,but not the only determinant of thesize of the left-to-right shunt. The level of pulmonary vascular resistance inrelation to systemic vascular resistance also determines the shunt'smagnitude.

When a small communication is present (usually < 0.5 mm2), the VSD iscalled restrictive and right ventricular pressure is normal. The higher pressurein the left ventricle drives the shunt left to right; the size of the defect limits themagnitude of the shunt.

In large nonrestrictive VSDs (usually >1.0 cm2), right and left ventricular pressure is equalized. In these defects, the direction of shunting and shuntmagnitude are determined by the ratio of pulmonary to systemic vascular resistance.

After birth in patients with a large VSD, pulmonary vascular resistance may

remain higher than normal, and thus the size of the left-to-right shunt mayinitially be limited. As pulmonary vascular resistance continues to fall in the 1stfew weeks after birth because of normal involution of the media of smallpulmonary arterioles, the size of the left-to-right shunt increases.

Eventually, a large left-to-right shunt develops, and clinical symptoms becomeapparent. In most cases during early infancy, pulmonary vascular resistance isonly slightly elevated, and the major contribution to pulmonary hypertension isthe extremely large pulmonary blood flow. In some infants with a large VSDpulmonary arteriolar medial thickness never decreases. With continuedexposure of the pulmonary vascular bed to high systolic pressure and highflow, pulmonary vascular obstructive disease develops. When the ratio of

pulmonary to systemic resistance approaches 0 .5 : 1, the shunt becomesbidirectional the patient becomes cyanotic (Eisenmenger syndrome).

Clinical Picture of VSD :

Small sized VSD :

Symptoms :

o Patients have mild or no symptoms.o These cases are most often brought to the cardiologist's attention

because a murmur is detected during routine examination.o Feeding or weight gain is usually not affected ( Normal thriving )

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Signs :

o Patients may have normal vital signs.o Physiologic splitting of S2 is usually retained.o The characteristic harsh, holosystolic murmur is loudest along the

lower left sternal border (LSB), and it is well localized. Small defectscan produce a high-pitched or squeaky noise.

o The murmur is usually detected after the PVR decreases at about 4-8weeks of age.

Medium sized VSD:

Symptoms:

o Babies may have excessive sweating due to increased sympathetictone. This sweating is especially notable during feeds.

o An important symptom is fatigue with feeding.o A sensitive symptom may be the lack of adequate growth (unable to

thrive), which is due to and an inability of the infant to feed adequatelyand decrease systemic blood flow .

o Frequent respiratory infections may occur secondary to the plethoriclungs.

o Symptoms, which begin as pulmonary vascular resistance (PVR)decreases, may be clearly apparent by age 2-3 months.

o Symptoms occur earlier in the premature infant than in the full-terminfant because pulmonary resistance decreases earlier in pretermbabies than in term babies.

Signs:

o Infants often have a normal length and decreased weight. Poor weightgain is a sensitive indicator of congestive heart failure (CHF).

o Infants may have mild dyspnea and tachypnea due to plethoric lungs .o Tachycardia ,gallop rhythm, tachypnea , and enlarged liver which

indicate heart failure .o The murmur with moderate-sized defects is usually associated with

thrill. A holosystolic harsh murmur is most prominent over the lower LSB.

o The intensity of the pulmonary component is usually normal or slightlyincreased.

o In addition to the harsh holosystolic murmur, a diastolic rumble may bedetected in the mitral area. This rumble suggests functional mitralstenosis secondary to a large left-to-right shunt qhich leads to increaseblood flow to the left atrium .

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Moderate (or medium-sized) VSDs are less likely than small defects to closeon their own. They may require surgery to close and may cause symptomsduring infancy and childhood.

Large VSD : With a large VSD (usually one greater than 1 cm2), there is

significant shunting of blood from the left ventricle into the right ventricle. Thusextra blood volume puts a strain on the right ventricle and causes an increasein the blood pressure of the lungs called "pulmonary hypertension." The childmay have labored breathing, difficulty feeding, grow poorly, and have pallor.

Complications:

A small ventricular septal defect may never cause any problems. Larger defects can cause a wide range of disabilities ² from mild to life-threatening.Treatment can prevent many of these complications.

Eisenmenger's syndrome: Ultimately, if a large ventricular septal defect goes untreated, increased blood

flow to the lungs causes high blood pressure in the lung arteries (pulmonaryhypertension). Over time, permanent damage to the lung arteries developsand the pulmonary hypertension can become irreversible.

This complication, called Eisenmenger's syndrome, may occur in earlychildhood, or it can develop slowly over many years. In people withEisenmenger's syndrome, the majority of the blood flow through the ventricular septal defect goes from the right ventricle to the left and bypasses the lungs.This means deoxygenated blood is pumped to the body and leads to a bluishdiscoloration of the lips, fingers and toes (cyanosis) and other complications.Once a person has Eisenmenger's syndrome, it's too late to surgically repair the hole because irreversible damage to the lung arteries has already

occurred.

Signs and Symptoms of Eisenmenger's syndrome

y Signs and symptoms of Eisenmenger's syndrome include: Gallstonesy Cyanosis, a blue tinge to the skin resulting from lack of oxygen.y High red blood cell county Swollen or clubbed finger tips(clubbing)y Fainting, called syncopey Heart failurey Arrhythmia or irregular heart rhythmsy Bleeding disordersy Coughing up bloody Iron deficiencyy Kidney problemsy Stroke

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Other complications may include:

Heart failure. The increased blood flow through the heart due to aventricular septal defect can also lead to heart failure, a chronic condition inwhich the heart can't pump effectively.

Endocarditis. People with a ventricular septal defect are at increased risk of an infection of the heart (endocarditis).

Stroke . People with large defects, especially occurring with Eisenmenger'ssyndrome, are at risk of a stroke due to a blood clot passing through thehole in the heart and going to the brain.

Other heart problems. Ventricular septal defects can also lead to abnormalheart rhythms and valve problems.

X-ray and ECG of VSD:

1-In patients with small VSDs, the chest radiograph is usually normal,although minimal cardiomegaly and a borderline increase in pulmonaryvasculature may be observed. The electrocardiogram is generally normal butmay suggest left ventricular hypertrophy. The presence of right ventricular hypertrophy is a warning that the defect is not small and that the patient haspulmonary hypertension or an associated lesion such as pulmonic stenosis.

2- In large VSDs, the chest radiograph shows gross cardiomegaly withprominence of both ventricles, the left atrium, and the pulmonary arteryPulmonary vascular markings are increased, and frank pulmonary edema,

including pleural effusions, may be present. The electrocardiogram showsbiventricular hypertrophy; P waves may be notched or peaked.

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Echocardiography

Cross sectional echocardiographic examination is now recognised as thetechnique of choice for diagnosis. Not only does the technique show thepresence of a defect, it also permits its accurate localisation. Furthermore,

because the defect should be identified in more than one plane, its size canbe estimated. Perimembranous defects are recognized in long-axis, four-chamber and short-axis views, with fibrous continuity between the leaflets of the tricuspid and mitral or aortic valves being the pathognomic feature.Perimembranous defects opening to the inlet of the right ventricle arerecognised by cuts through the ventricular inlets The four-chamber sectionswill demonstrate continuity between the leaflets of the tricuspid tomitral valves via the central fibrous body, with loss of the usual off-setting of the hingepoints of the leaflets. A gentle sweep of the transducer from a four-chamber cut to a long axis cut will demonstrate the continuity of the leaflets of the tricuspid and aortic valves through the centralfibrous body. In the so-called juxta-tricuspid and

non-perimembranous defect, the defect is describedas being at some distance from the aortic valvebecause it does not reach the central fibrous body.We initially believed that we had identified such adefect echocardiographically. When the surgeonclosed the defect, however, he discovered amuscular ridge separating the hinges of thetricuspid and mitral valves in the roof of the defect.

Hence, the defect was surrounded by muscle,and opened to the inlet of the right ventricle in other words a muscular inlet defect. It remains the fact,

therefore, that we have still to identify a patient witha juxta-tricuspid and non-perimembranous defect,either in the clinical setting or at autopsy. Defectsopening between the outlets are best identified in the subcostal right obliquesection, which shows the muscular outlet septum as an interventricular structure immediately beneath the subpulmonary infundibulum. ( This isevidence of the biventricular aortic connection).The parasternal short-axis cut at the level of the aortic valve will similarlyshow this discrete outlet septum). When this feature is present, theparasternal long-axis section will usually demonstrate overriding of the leafletsof the aortic valve For those defects opening between the outlets, andassociated with posterior longitudinal deviation of the outlet septum, usually inthe setting of aortic coarctation or interruption, the parasternal long-axissection will be the optimal plane for diagnosis. Muscular defects opening tothe right ventricular inlet are best seen in the four-chamber view, but retain thefeature of atrioventricular valvar off-setting. Large defects within the apicaltrabecular septum are identified in four-chamber and short-axis planes, whilemuscular defects opening to the subpulmonary outlet are identified in short-axis or right anterior oblique planes from parasternal or subcostal approaches.The best view with which to distinguish perimembranous from muscular outlet

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reconstruction. Such techniques, while not yet generally available, haveimmense potential, as shown by the reports describing their value.

Doppler Interrogation

The complete evaluation of a ventricular septal defect includes not only anassessment of the size, site and number of defects, but also an estimate of the haemodynamic consequences. By using continuous wave Doppler ultrasound, it is possible to measure the velocity of flow across any ventricular septal defect. Then, by invoking the principles of the Bernoulli equation, it ispossible to calculate the instantaneous peak systolic pressure drop betweenthe ventricles. Assuming that the left ventricular peak systolic pressure is thesame as the systolic blood pressure, the right ventricular systolic pressure can

then be estimated. In the absence of any obstruction within the rightventricular outflow tract, this can be presumed to be equal to the pulmonaryarterial systolic pressure. Infants and children with congenital cardiac defects,including those with a ventricular septal defect, frequently have mild tricuspidinsufficiency. In this situation, it is possible to estimate the pressuredropacross the tricuspid valve and, therefore, to estimate the right ventricular and pulmonary arterial systolic pressures. A potential source of error ariseswhen there is a shunt from left ventricle to right atrium through the defect via adeficiency in the septal leaflet of the tricuspid valve. In this situation, theregurgitant jet reflects the pressure drop between the left ventricle and rightatrium. Colour flow mapping has greatly facilitated the echocardiographicdiagnosis of ventricular septal defect. Its most important uses include

accurate alignment of the

Doppler beam with the flow of blood, thus enhancing accurate quantificationof velocity, the detection of multiple ventricular septal defects, and thedemonstration of shunting from left ventricle to right atrium. Colour flowmapping also plays a role in distinguishing innocent murmurs from thosecaused by very small ventricular septal defects.

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Cardiac Catheterisation

Prior to the advances made in cross sectional echocardiography,catheterisation was an essential part of the assessment of patients havinglarge restrictive and unrestrictive defects. It made possible the measurementof intracardiac pressures, particularly the pulmonary arterial pressure, alongwith quantification of the flow of blood to the lungs. This information made itpossible to calculate the pulmonary vascular resistance. In addition, thetechnique provides confirmation of the interventricular location of the defect bythe detection of a step-up in saturation of oxygen at ventricular level, or byvisualisation of the passage of the catheter from right to left ventricle or to theaorta. If the defect is modified by abnormal attachments of the leafletsnof thetricuspid valve, such that the shunt is from left ventricle to right atrium, thenthe step-up in saturation of oxygen is detected in the right atrium. This is also

found when a ventricular septal defect co-exists with an atrial septal defect, or when there is an atrioventricular septal defect.

Cardiac catheterisation provides further information about the associateddefects. Passage of the catheter from the pulmonary trunk to the descendingaorta, for example, indicates the presence of a communication between thesetwo arteries, usually an arterial duct. The findings at catheterisation reflect thepathophysiology. Unrestrictive defects with a high pulmonary blood flow havesimilar pressures in right and left ventricles. With an unobstructed rightventricular outflow tract, and a low pulmonary vascular resistance, thepulmonary arterial systolic pressure will be similar to that in the aorta. Thediastolic and mean pulmonary arterial pressures will be lower than aortic

pressures. In such cases, a high flow to the lungs will be measuredoximetrically, or in the past by dye dilution curves. In large but restrictivedefects, the right ventricular and pulmonary arterial pressures will be lower than those in the left ventricle and aorta. The main current indication for cardiac catheterisation other than for interventional closure of the defect is toestablish, beyond doubt, that patients suspected to have pulmonary vascular disease do have an elevation of pulmonary vascular resistance so great as torender them inoperable. found on cardiac catheterisation. This is bestperformed in the 45-degree head-up position using antero-posterior and

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lateral projections. Left ventricular angiograms can be used for quantitativeassessment of left ventricular function. Left ventricular enddiastolic volume isusually increased, and the ejection fraction is normal or increased. Theseindexes have prognostic significance but rarely, if ever, will the decisionwhether or not to opt for closure be influenced by these findings. Nowadays, itis rarely necessary to perform invasive studies in infants with ventricular septal defects. All the necessary information required to determine the needfor surgical

Treatment of VSD: the treatment of the VSDs first was depending on

the appearance of the symptoms of heart failure or cardiac overload but now

with the development of the transcatheterization and non invasive devices

beside the surgery, there is no point in leaving a VSD opened ( even if it was

small and asymptomatic ).

Transcatheter:

Technique:

The catheter needle is inserted in certain sites

( groin, neck) in the vein or artry.

Most commonly inserted in the groin in the

femoral artry then the needle goes up in the aortauntil reached the left ventricles then it pass

through the defect (VSD) then the device is put

at the site of the defect then its inflated to

close the VSD

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Indications:

usually there is no need to await the symptoms to

accour but the most common indications are:

1-symptoms of heart failure.2- signs of left heart chambers overload3- recurrence of endocarditis4-preventionof pulmonary arterial hypertension, ventricular dysfunction,arrhythmias and aortic regurgitation.5-its indicated mainly in small VSDs.

Contraindications:

1-Severe uncontrolled hypertension2-Ventricular arrhythmias3-Acute stroke4-Severe anemia

5-Active gastrointestinal bleeding6-Acute renal failure7-Uncompensated congestive failure (patient cannot lie flat).8-Unexplained febrile illness and/or untreated active infection.9-Electrolyte abnormalities (eg, hypokalemia)10-Severe coagulopathy..11- heamoragic disorders.Before any diagnostic or theraputic catheterization the above complicationsshould be managed first to ensure successeful catheterization.

Absolute contraindication :1-aortic stenosis (never try arterial transcatheterization)

2-pulmonary hypertension.(usually requires surgery and no need or benefitfrom transcatheterization).

Complications:

1-malposition or dislocation of the transcatheter device.2-injury of the femoral artery at the puncture site3-left ventricular perforation after dislocation of the device.4- embolization of the device in any vein ( iliac vein device embolization wasreported).5-in some occluder devices over-inflation of the ballons lead to more wideningof the defect.

Surgery: its the gold standard in treatment of any septal defects including theVSDs but we should consider it as the last solution because of its highmorbidity and mortality besides the patient refusal (most of times).Before any cardiac surgery All imaging studies should be reviewedpreoperatively to clearly visualize the defect(s) and to assess for the presenceof other intracardiac anomalies. These studies delineate the anatomicsubstrate and allow appropriate planning for the operation

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Indication:

1-its the gold standard to close any septal defect including VSDs but itsrecommended in large VSDs or when other non-invasive procedurs .2-To handle the complication of malpositioned or dislocated patch(ex:complications of transcatheter).3-multiple cardiac defects ( multiple VSDs).

Complication:

1-infection2-postoperative bleeding requiring re-exploration3- valve injury (tricuspid, pulmonary, or aortic) leading to valve regurgetation4-pulmonary hypertension with poor cardiac output5-atrioventricular (AV) heart block6-residual VSD with continued left-to-right shunting

7-death.

Permanent AV heart block occurs in 1% or fewer of children undergoing VSDclosure. Care must be taken to correctly identify the position of the defect,since this determines the location of conduction tissue and directs the repair to avoid conduction injury. Transient AV block is treated expectantly withtemporary cardiac pacing. When AV conduction does not return (in <1% of patients in the best centers), a permanent pacemaker is needed.

Residual left-to-right shunt from incomplete VSD closure may result frominsufficient intraoperative exposure or suture disruption with patchdehiscence. Significant residual shunting is most commonly observed inmuscular defects (particularly multiple defects) in which trabeculationsdecrease visualization of the full extent of the VSD(s). Residual shunting withQp:Qs greater than 1.5:1 occurs in 2% or fewer of patients and should promptreoperation.

The mortality rate associated with surgical VSD closure has decreaseddramatically with improvements in perfusion, myocardial protection, andpostoperative care. The overall surgical mortality rate for patients with isolatedVSD is less than 1%, and the mortality rate for low-risk candidates isminiscule. Risk factors for mortality include severe associated noncardiacanomalies, multiple VSDs, and major associated cardiac anomalies.

N.B: before any intervention and trials to close any VSD we should leaveadequet time for the VSD to close sponteniously.( as most of VSDs tend tohave nature history of closure without any treatment ).

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