Ventricular septal defectQ21.0

In 1888, Etienne Louis Arthur Fallot was the first to describe the ventricular septal defect in the context of the Fallot tetralogy (Briese 2015).

A ventricular septal defect (VSD) is a pathological opening between the right and left ventricle.

The VSD has various classification options. The most common classifications are:

1. classification by defect localization (Herold 2019)

• Type 1: supracristal, subarterial, conal, subpulmonary, doubly committed, infundibular, juxta- arterial outlet
• Type 2: Conoventricular, paramembranous, perimembranous
• Type 3: AV channel type, inlet
• Type 4: Trabecular, muscular

2. classification according to haemodynamic effect (Herold 2019)

• restrictive VSD: the pressure in the right ventricle is lower than the pressure in the left ventricle
• non-restrictive VSD: there is a pressure equalization at ventricular level

3. classification by components (Pinger 2019)

• Membranous or perimembranous VSD: Here the defect is located between the inflow and outflow tract of the muscular septum close to the base in a small area below the right coronary and acoronary pocket of the aortic valve. A perimembranous defect is a membranous VSD with involvement of the muscular part.
• Muscular VSD:
  • VSD of the trabecular septum (anterior, posterior, midmuscular, apical, VSD according to Kirklin)
  • VSD of the outflow tract, subpulmonary, infundibular, conal, conoventricular VSD, bulbous septal defect, outlet- septal defect, double committed subarterial defect
  • VSD in the influence tract, in the area of the AV valves, inlet- septum defect, AVSD
• Multiple defects
• Left ventricle- right atrial septum defect (for high defect)

Pathophysiology

The VSD causes a left-right shunt. The size of the defect and the resistance ratios of the two circuits determine the shunt quantity. The shunt volume can be up to 20 l / min in extreme cases. The effective cardiac output is usually normal (pinger 2019).

The shunt results in a volume load of the ventricles, the left atrium and the pulmonary vessels. However, the right ventricle is not always affected (the volume load on the right ventricle may be less if the left ventricle ejects part of the shunt volume directly into the pulmonary artery [pinger 2019]). In a small and medium-sized VSD, neither volume stress nor hypertrophy are primarily seen (Herold 2019). If there is a large shunt, damage to the pulmonary vessels may occur. This damage leads consecutively to secondary pulmonary hypertension and an increase in pulmonary resistance (Pinger 2019).

Small or medium-sized defects cause pressure separation, whereas large defects cause pressure equalization. The ratio of lung to system resistance is decisive for shunt flow (Herold 2019).

The severity of a VSD is determined by the ratio of pulmonary (Qp) to systemic flow (Qs).

• Small VSD (also known as M. Roger):
  • where the ratio Qp / Qs is less than 1.5: 1
  • the diameter is < 25 % of the aortic annulus diameter
  • there is no significant enlargement of the heart cavities
  • initially the pressure in the right ventricle and also in the pulmonary artery is normal
  • the pressure may increase to 1/4 to 1/3 of the system pressure as the process progresses
  • there is a left-right shunt throughout the entire cardiac cycle
• Mid-size VSD
  • the ratio of Qp / Qs is 1.5 - 2: 1
  • the diameter is 25 % to 75 % of the aortic annulus diameter
  • there is a clear overperfusion of the lungs
  • both the left atrium and the left ventricle are clearly enlarged
  • the right ventricle is almost unchanged in size
  • in the right ventricle the pressure rises to 1/3 to 1/2 of the system pressure (PAP / SP ≤ 0.5)
• large VSD:
  • Qp / Qs > 2:1
  • the diameter is > 75% of the aortic annulus diameter
  • the defect is no longer restrictive
  • Shunt blood is directed with system pressure into the right ventricle as well as into the pulmonary artery (PAP / SP > 0.5)
  • Signs of right heart strain are present

After years of a larger VSD, it comes to

• an obstructive pulmonary vascular disease (known as Eisenmenger's reaction )
• there is extensive irreversible reconstruction of the pulmonary vessels
• the pulmonary vascular resistance increases to the level of the system resistance
• This causes a shunt reversal (right-left shunt)
• cyanosis develops

Spontaneous course

• In children: Children with a small shunt usually show no symptoms. Spontaneous occlusions are frequent and occur preferably until the age of 7. With a large shunt there is a risk of developing left heart failure initially. In the course of time, right heart failure develops due to increasing pulmonary hypertension and the development of Eisenmenger's syndrome (Pinger 2019). Deaths are possible already in childhood (Kasper 2015).
• In adults: The spontaneous course of a VSD in adulthood can vary greatly. The following possibilities exist:
  • Spontaneous closure occurs in approx. 85% - 90% of cases; the smaller the VSD is, the more likely it is (Pinger 2019); it occurs predominantly in perimembranous or muscular VSD; spontaneous closure is not possible in outlet VSD (Herold 2019)
  • aortic valve insufficiency may develop in 1.4% - 6.3% of cases (Pinger 2019); this is caused by prolapse of the right or acoronary valve pocket; this process occurs relatively frequently with outlet VSD (supra-crystalline) and perimembranous VSD; progression is frequent in the further course; an association with the sinus-valsalva aneurysm is possible; in this case there is a risk of rupture
  • the stunt may increase in size as it progresses and surgery may be required if symptoms occur
  • Occurrence of endocarditis; this develops up to 6 times more frequently than in the normal population (Herold 2019); without surgery, an average of 19 endocarditis cases per 10,000 patient-years, postoperatively, however, only 7.5 per 10,000 patient-years (Pinger 2019)
  • Arrhythmias can occur
  • Block images are possible
  • a so-called "double chambered right ventricle" (DCRV) can develop
  • a discrete subaortic valve stenosis may occur
  • subpulmonary stenosis can occur in 3 % - 5 % of cases due to myocardial hypertrophy in the right ventricular outflow tract (RVOT)
  • occurring pulmonary hypertension is associated with increased mortality; with a mean pulmonary arterial pressure of < 20 mmHg, the 20-year survival rate is estimated to be 97%; with a mean pulmonary arterial pressure of > 20 mmHg, the 20-year survival rate is 76% significantly increased risk of sudden cardiac death; 35%-39% of cardiac mortality is due to sudden cardiac death (Pinger 2019)

The ventricular septal defect, as an isolated form, is one of the most common congenital vitae (Herold 2018) with about 35% and as a combined form it is the second most common form of vitae. It occurs in about 50% of all congenital heart defects (Pinger 2019). The incidence of live births is about 3/1,000, and in adulthood the prevalence is about 0.3/1,000 (Pinger 2019). m:w=1:1;

The VSD is usually congenital.

In rare cases a VSD may be acquired. The cause can then be a myocardial infarction or chest trauma (Pinger 2019).

Anatomy of the VSD

A distinction must be made between the:

• inlet- septum; here both AV valves are separated from each other.
• outlet- septum (outlet septum); this extends from the supraventricular crista to the pulmonary valve
• Trabecular septum; this extends from the insertion of the chordae to the apex and cranial to the supraventricular crista
• membranous septum

The clinical symptoms depend on the location of the defect, its size, shunt volume and pulmonary resistance.

• Small VSD:
  • In this case, there are no symptoms at all in a left-right shunt < 30 % (Pinger 2019)
• Medium or large VSD:

With a left-right shunt of 30 % to 50 %, growth and child development are usually normal, but physical capacity may already be limited (Pinger 2019). From a left-right shunt of > 50% (Pinger 2019) the following changes can occur:

• Delays in development and growth

• there is stress dyspnea

• recurrent pulmonary infections become more frequent

• Palpitations are possible (for both ventricular and supraventricular arrhythmias)

The following changes can occur when Eisenmenger's syndrome develops:

• Restriction of the physical ability to work under pressure or performance
• Dyspnea, initially under stress, later also at rest
• Hemoptoe
• Cyanosis
• Cardiac arrhythmia
• Development of right heart failure
• Syncopes
• Brain abscess

Chest X-ray

• Small VSD:
  • usually no radiological changes can be found
• Medium VSD:
  • Dilatation of the pulmonary artery
  • Dilatation of the pulmonary vessels (Pinger 2019)
• Large VSD:
  • dilatation of the left ventricle and the left atrium
  • possibly dilated right ventricle (Pinger 2019)
  • the transverse diameter of the heart is enlarged
  • the truncus pulmonalis presents prominently
  • narrow aorta
  • both central and peripheral lung markings are increased
• Eisenmenger syndrome:
  • heart size is predominantly normal
  • emphasis of the right ventricle
  • widening of the pulmonary trunk
  • decrease of peripheral pulmonary vascular drawing (so-called caliber jump towards the periphery)

Echocardiography

Echocardiography can provide more detailed information on:

• Localization and size of the VSD
• Dilatation of the left atrium
• dilatation of the left ventricle
• dilated pulmonary trunk
• In Doppler procedure:
  • estimation of right ventricular and pulmonary artery pressure
  • Determination of the interventricular pressure gradient
  • Statements on shunt direction
  • estimation of Qp/Qs possible (lung time volume/body time volume)
  • Cardiac output
• In contrast echo, representation of contrast crossover (Pinger 2019).

MRI

If an isolated VSD is present, echocardiography usually ensures adequate diagnosis. In adults with poor sound conditions, cardio- MRI offers the best possibility for diagnosis (Pinger 2019). Here, it is possible to depict:

• Determination of the ventricular volumes
• function of the ventricles
• exact visualization of the defect
• Shunt quantification with measurement of Qs: Qp
• Visualization of other abnormalities (Pinger 2019).

Cardiac catheterization

Cardiac catheterization is required when more detailed information on functional relevance is needed. Possible tests here are:

• Determination of pulmonary arterial pressure (PAP).
• Determination of intraventricular pressures
• Verification of ventricular pressures
• more detailed information on the size of the shunt (floor oximetry for shunt quantification [Pinger 2019])
• determination of pulmonary vascular resistance
• statements on pulmonary vessel morphology (in patients with Eisenmenger's syndrome, however, angiography should be avoided because of the high complication rate)
• exclusion or detection of other cardiac anomalies
• possibly performance of an aortography to show or quantify an additional aortic insufficiency
• in men > 40 years evaluation of the coronary arteries

Laboratory Compensatory erythrocytosis occurs in the context of an Eisenmenger syndrome (Kasper 2015).

Inspection

If the patient is (still) asymptomatic, there may be:

• a normal jugular vein pulse
• a cardiac hump (voussure) may be present; this is a protrusion in the area of the 4th - 6th rib on the left parasternal side (Gruber 2919)

In the presence of Eisenmenger's syndrome are present:

• steadily progressive cyanosis
• Clock glass nails
• drumstick finger

Palpation

• there is a low blood pressure with small amplitude
• there is a systolic buzzat the lower left sternal border
• the cardiac apex is widened, hyperactive and displaced downward and outward.

If Eisenmenger's syndrome is present, the following may be present:

• the left ventricular pulse is weakened or absent
• the pulmonary valve closure is palpable
• lifting pulsations over the right ventricle and its outflow tract.

Auscultation

• In small VSD:
  • in the 2nd ICR left regular split 2nd heart sound
  • in the 3rd/4th ICR left parasternal the typical VSD sound can be auscultated: a high frequency, early systolic compressive jet sound (in small and medium VSD the sound is often louder than in large VSD [Pinger 2019])
• In medium and large VSD:
  • respiratory variable, regular splitting of the 2nd heart sound
  • the 2nd heart sound is often masked by the compressive jet sound
  • in pulmonary hypertension, a loud pulmonary valve component may be auscultated
  • a 3rd heart sound may occur (found in a hemodynamic left-right stunt; the cause is the voluminous and rapid filling of the left ventricle due to recirculating shunt blood [Franke 2013])
  • in the 3rd/4th ICR left parasternal systolic flow murmur is found. If relative mitral stenosis is present, a diastolic over the cardiac apex may be auscultable (Pinger 2019).
• In Eisenmenger's VSD:
  • in the 2nd ICR on the left, a singular, tympanic 2nd heart sound is auscultable
  • in the 2nd/3rd ICR left parasternal a short, mesosystolic interval murmur
  • right atrial a 4th heart sound is present
  • pulmonary ejection murmur
  • the typical VSD murmur in the 3rd/4th ICR on the left is absent
  • diastolic, decrescendo interval murmur in the 2nd ICR on the left (so-called Graham- Steel murmur in pulmonary valve insufficiency).

ECG

• In a small VSD, the ECG is usually unremarkable.
• In medium or large VSD, there are:
  • Steep to left type
  • P- sinistroatrial or also called P- mitral (P > 0.11 sec. in Abl- II, double-peaked P- wave with emphasis on the 2nd peak [Herold 2018]).
  • Signs of left ventricular hypertrophy
    • Sokolow- Lyon index: SV1 + RV5 or RV6 > 3.5 mV (Herold 2018).
    • QRS- complex widened
    • Left bundle branch block
    • High R- jags in I, aVL, V4- V6 (Hamm 2014).
• In Eisenmenger's VSD:
  • Steep to right type
  • Signs of right ventricular hypertrophy.
    • P- pulmonale ( also called P- dextroatrial; the P in II and III is peak positive with > 0.2 mV and in V1 , V2 the positive portion of the P- spike is peak positive and higher than 0.15 mV)
    • incomplete or complete right bundle branch block
    • Sokolow- Lyon index as a sign of right heart hypertrophy ( RV1 +SV5/6 > 1,05 mV)

Long-term ECG

• Long-term ECG often shows complex ventricular arrhythmia. Ventricular tachycardia is also possible. These occur in approximately 5% of patients with mild to moderate VSD and in approximately 19% of patients with Eisenmenger syndrome (Pinger 2019).

The treatment of a VSD consists of conservative measures, surgical treatment and interventional therapy, depending on the severity of the clinical picture.

Conservative therapy: In patients with a small VSD who do not yet show any symptoms and who do not have pulmonary hypertension (Qp: Qs < 1.5: 1), it is recommended to wait and perform sporadic follow-ups (Pinger 2019).

Patients with congenital vitium and existing pulmonary hypertension have the worst prognosis of all patients with congenital vitium and pulmonary arterial hypertension after shunt occlusion (Pinger 2019).

The indication for surgical intervention is given according to ESC 2010:

• Indication class I:
  • symptomatic patients who do not have severe pulmonary hypertension
  • asymptomatic patients with signs of volume overload of the left ventricle
• Indication class IIa:
  • patients with endocarditis
  • Prolapse of the aortic valve with increasing aortic regurgitation (Pinger 2019).
• Patients with Eisenmenger's syndrome:
• In this case, lung transplantation with closure of the VSD or heart-lung transplantation should be performed (Herold 2019).

No closure of the VSD should be performed for:

• severe, irreversible pulmonary hypertension with a PA- pressure > 2/3 of adult arterial pressure or pulmonary vascular resistance (PVR) > 2/3 of total peripheral resistance (SVR) [(Pinger 2019)]
• A PVR > 8 Wood units
• Patients with exercise-induced cyanosis
• VSD with Eisenmenger's syndrome [(Pinger 2019)].

Surgery should not be performed for a small ventricular septal defect in:

• absence of volume stress and
• without infective endocarditis and
• without pulmonary arterial hypertension

Op- Technique:

Surgery is usually performed transtricuspidally from the right atrium to avoid ventriculostomy. Depending on the location of the defect, access may also be from the right or left ventricle or through the pulmonary artery. The closure itself is performed by

• Direct suture
• Patch closure

Op- mortality is < 1.4% (Pinger 2019).

Interventional Therapy:

For muscular or perimembranous VSDs, the catheter interventional procedure is increasingly used to close the defect (Herold 2019). Interventional therapy is also suitable for patients at increased risk of surgery. Procedural success can be expected in 95% of cases. In patients with a mean VSD diameter of 5 mm-6 mm, a meta-analysis has shown no difference between surgical and interventional treatment with regard to early outcomes (Pinger 2019). The lethality rate here depends on age, number of defects, any associated anomalies, pulmonary artery pressure, and pulmonary vascular resistance. In an uncomplicated VSD, the lethality rate is <2%. If reoperation is required, the rate is higher. Specific figures on this are not available.

Postoperatively,:

• in approx. 65 % of the patients a right bundle branch block occurs
• in approx. 3 % of patients an AV block III (Pinger 2019).

In addition, may occur:

• a bifascicular block
• ventricular arrhythmias
• disturbances of right and left ventricular function
• progression of obstructive pulmonary vascular disease
• re/residual shunts
• persistent risk of endocarditis
• Sudden cardiac death (occurs in 11% of patients [Pinger 2019]).

With early surgery, freedom from symptoms is achieved in 97% in NYHA I. Mortality over > than 10 years is 5%. Re-operations are required in approximately 4%. Aortic regurgitation develops in 16%. Sinus node disease with pacemaker requirement is found in 4% (Pinger 2019).

With a small VSD or an uncomplicated closed VSD there are no sporting restrictions.

In a small VSD without pulmonary arterial hypertension or an uncomplicated occluded VSD there is no contraindication for contraception or pregnancy (Pinger 2019).

Follow-up examinations should be carried out in children by a paediatric cardiologist at large intervals (not defined in detail) until the end of the growth phase. In adulthood, no further regular check-ups are required for sinus rhythm, normal AV transition, residual defect-free findings, normal heart size and function and proper valve function.

For uncorrected small restrictive VSDs, lifelong monitoring should be performed. There is currently no recommendation for endocarditis prophylaxis.

Endocarditis prophylaxis is recommended postoperatively in the first 6 months. After that, prophylaxis is only necessary if a residual shunt persists (Dittrich 2013).

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