Cardiovascular medicine

Key Points

• Ischaemic heart disease is common and potentially fatal

• Stress and anxiety can precipitate cardiac events

The heart is vital to life, as its essential function is pumping oxygenated blood to the brain and vital organs. Blood is oxygenated in the lungs and travels in the pulmonary vein to the heart at the left atrium, from where it flows to the left ventricle through the mitral valve. Blood leaves the left ventricle through the aortic valve to the aorta (the body’s main artery) and is distributed via arteries throughout the body. Thus the left ventricle is the most powerful chamber, as it has to move blood all around the body. Oxygen is transported on the red blood-cell (erythrocyte) pigment haemoglobin, which colours the blood red. Arteries branch to arterioles and then to capillaries to transport oxygen to the tissues (Fig. 5.1) and collect waste carbon dioxide. A vast venous network collects deoxygenated blood from all the tissues and returns it to the superior vena cava and inferior vena cava and thence to the right atrium of the heart (Fig. 5.2). This blood flows through the tricuspid valve to the right ventricle and then leaves the right ventricle through the pulmonary valve to the pulmonary artery and thence to the lungs, where it takes up oxygen. The heart thus consists of four chambers: two ventricles and two atria. It is centrally located in the chest (thorax) but, because the left ventricle is larger, the heart beat (apex beat) is found to the left side (Fig. 5.3).

The heart rate and force of contraction are controlled by nerves (mainly vagus and sympathetic) and hormones (especially adrenaline [epinephrine], which increases both rate and force). Anxiety and exercise can increase the pulse rate and force of the heart beat.

Heart disease is a major killer; in the USA, possibly one person dies from heart disease every 30 seconds. It also causes significant morbidity and disability in many aspects of life, including effects on entitlement to drive a motor vehicle. There is a wide range of disorders that can affect the heart (Box 5.1).

Congenital Heart Disease (CHD)

General aspects

Congenital heart defects are the most common type of heart problem in children, present in about 1% of live births. Lesions may involve the heart or adjacent great vessels, in isolation or in a variety of combinations, and include a wide variety of structural defects that can lead to malfunction such as arrhythmias or flow problems. Vessel or valve stenosis or obstruction and septal defects strain the myocardium.

The types of CHD are summarized in Table 5.1. CHD may be: cyanotic (‘blue babies’), where there is right-to-left shunting – in general these are more severe defects; or acyanotic. Cyanosis and hypoxia can lead to neurological deficits, polycythaemia (with hypercoagulability and thromboses) and systemic infections (e.g. brain abscess). Approximately 20% of patients with CHD also have other congenital anomalies.

Table 5.1

Types of congenital heart disease a

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	Acyanotic
Cyanotic	With no shunt	With left-to-right shunt
Eisenmenger syndrome	Aortic stenosis (AS)	Atrial septal defect (ASD)
Fallot tetralogy	Bicuspid aortic valve	Patent ductus arteriosus (PDA)
Pulmonary atresia (PA)	Coarctation of the aorta	Ventricular septal defect (VSD)
Pulmonary valve stenosis	Dextrocardia
Total anomalous venous drainage (TAVD)	Mitral valve prolapse
Transposition of the great vessels
Tricuspid atresia (TA)

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^aSee also Table 5.2.

The cause of CHD is often unidentified but some causes are genetic (e.g. Down syndrome; see Ch. 28). There are many other causes (Table 5.2; Appendices 5.1 and 5.2) and syndromes (e.g. oesophageal atresia and heart disease, and forearm/digit abnormalities and atrial septal defect [ASD]). The main acquired causes of CHD are maternal infections such as TORCH – congenital toxoplasmosis, rubella, cytomegalovirus or herpes infection – which can lead to patent ductus arteriosus (PDA), pulmonary stenosis, ventricular septal defect (VSD) and coarctation of the aorta; maternal drug use (e.g. alcohol, anticonvulsants, lithium, recreational drugs, thalidomide and warfarin); or maternal systemic disease (systemic lupus erythematosus and Sjögren syndrome [both can cause heart block], and diabetes [which is associated with an increased incidence of VSD, coarctation and transposition of the great arteries and/or a characteristic hypertrophic cardiomyopathy]); and, rarely, maternal irradiation.

Table 5.2

Main features of congenital heart disease (CHD)

CHD	Main pathology/location	Main features
Aortic stenosis	Narrowing of the aortic valve	Angina, dyspnoea and syncope. Balloon valvuloplasty or surgery may be indicated
Atrial septal defect (ASD)	Usually near foramen ovale and termed a secundum defect. Associated in 10–20% with mitral valve prolapse	Initially acyanotic, with survival into middle age in most cases, and therefore is the most common CHD presenting in adults. In the absence of surgical correction, right ventricular failure eventually develops. Usually repaired by primary closure or by pericardial or Dacron patch
Bicuspid aortic valve	Valve is bicuspid instead of tricuspid. Often associated with other left-sided lesions (e.g. coarctation of the aorta or interrupted aortic arch)	Usually asymptomatic, even in athletes, but there is a high risk of infective endocarditis
Coarctation of the aorta	In the aorta beyond the origin of the subclavian arteries	Normal blood supply to the head, neck and upper body but restricted to the lower body. Surgery is indicated
Dextrocardia	Right-sided heart	Usually asymptomatic but may be part of situs inversus (all organs transposed) with bronchiectasis and sinusitis (Kartagener syndrome)
Ebstein anomaly	Congenital abnormality of the tricuspid valve, usually associated with ASD	Ebstein anomaly is mild in most and surgery is needed only if the tricuspid valve leaks severely enough to result in heart failure or cyanosis
Eisenmenger syndrome or reaction	The process in which a left-to-right shunt in the heart causes increased flow through the pulmonary vasculature (and pulmonary hypertension) which, in turn, causes increased pressures in the right heart and reversal into a right-to-left shunt	Ventricular or atrial septal defects, patent ductus arteriosus and more complex types of acyanotic heart disease can underlie this. Initially there is pulmonary hypertension, polycythaemia and a hyperviscosity syndrome with haemorrhagic and thrombotic tendencies. Later there is right ventricular hypertrophy and cyanosis. Anticoagulants and pulmonary vasodilators (e.g. bosentan) may be indicated
Fallot tetralogy	Ventricular septal defect, pulmonary stenosis, right ventricular hypertrophy and an aorta that overrides both ventricles. Fluconazole use in pregnancy may predispose	Cyanosis progressive from birth. Chronic hypoxia causes decreased neurological function. Episodes of acute hypoxia from infundibular spasm are life-threatening. Polycythaemia causes hypercoagulability and thrombosis. Right-to-left shunting is associated with a higher incidence of systemic infection such as a brain abscess. Surgery is indicated
Mitral valve prolapse (floppy mitral valve; Barlow syndrome)	The most common CHD, affecting 5–10% of the population. Seen mainly in women. Strong hereditary tendency. Seen especially in Marfan, Ehlers–Danlos and Down syndromes. May be associated with polycystic kidney disease and panic disorder	May cause no symptoms but, if there is mitral regurgitation, some patients develop pain, irregular or racing pulse, or fatigue and heart failure
Patent ductus arteriosus (PDA)	A persistent opening (normally closed by the third month of life) between aorta and pulmonary artery, common in prematurity and maternal rubella	Shunt is left to right, initially acyanotic, and a typical complication is right ventricular failure. Closure can be promoted in early infancy by giving intravenous indometacin, a prostaglandin inhibitor
Patent foramen ovale	Communication between atria	Often symptomless
Pulmonary atresia	No pulmonary valve exists, so blood cannot flow from the right ventricle into the pulmonary artery and to the lungs. The right ventricle is not well developed. The tricuspid valve is often poorly developed. An ASD allows blood to exit the right atrium, so the baby is cyanotic. The only source of lung blood flow is the PDA	Early treatment often includes using a drug to keep the PDA from closing, and surgery to create a shunt between the aorta and the pulmonary artery
Pulmonary stenosis	Narrowing of the pulmonary valve	Symptoms are breathlessness and right ventricular failure. Balloon valvuloplasty or surgery may be indicated
Total anomalous pulmonary venous return (TAPVR)	Blood returns from the lungs to the right rather than left atrium	Survivors also have ASD or patent foramen ovale
Transposition of the great vessels	Reversal of pulmonary artery and aorta origins	Cyanosis and breathlessness from birth, with early congestive cardiac failure and death in infancy unless there are associated defects providing sufficient collateral circulation (such as a patent interventricular septum or PDA)
Tricuspid atresia	Absence of the tricuspid valve means no blood can flow from the right atrium to the right ventricle. Thus the right ventricle is small. Survival depends on there being an ASD and usually a ventricular septal defect	A surgical shunting procedure is often needed to increase the lung blood flow and reduce cyanosis. Some children may need pulmonary artery banding to reduce blood flow to the lungs. Others may need a more functional repair (Fontan procedure)
Ventricular septal defect (VSD)	One of the most common CHDs. Ranges from a pinhole compatible with survival at least into middle age, to a large defect causing death in infancy if untreated. Some 90% of children with VSD have an additional cardiac defect	Initially left-to-right shunt but, with right ventricular hypertrophy, shunt may eventually reverse with late-onset cyanosis. Right ventricular failure may develop. Usually repaired by primary closure or by a pericardial or Dacron patch

Clinical features

Cyanotic CHD is, in general, a much more severe defect than acyanotic (Fig. 5.4), which can lead to cardiac failure or be life-threatening or fatal without surgical intervention. In the absence of treatment, 40% of children with cyanotic CHD die within the first 5 years. Cyanosis (caused by>5 g of reduced haemoglobin per decilitre of blood) results from shunting deoxygenated blood from the right ventricle into the left side of the heart and the systemic circulation (right-to-left shunt), and leads to chronic hypoxaemia (Fig. 5.5). Patients may crouch in an effort to improve venous return but eventually polycythaemia develops – with consequent haemorrhagic or thrombotic tendencies. Finger- and toe-clubbing are associated with cyanotic CHD, but appear after about 3 months of age (Fig. 5.6). Patients with CHD are liable to a range of complications (Box 5.2).

Fig. 5.4 Central cyanosis in a child with a congenital heart defect, showing purple lips and gingivae.

Fig. 5.5 **Chest radiograph of a child with congenital heart disease showing gross cardiac enlargement.**
(The heart normally occupies less than half the width of the chest).

Fig. 5.6 **Finger-clubbing in a patient with Fallot tetralogy.**
Finger-clubbing can be found in several different disorders, particularly cyanotic heart disease, chronic respiratory disease, lung cancer, Crohn disease, etc., but is sometimes benign and hereditary.

Box 5.2

Possible complications in congenital heart disease

• Bleeding tendency

• Cardiac failure

• Cyanosis

• Fatigue

• Growth retardation

• Infections (e.g. brain abscess, endocarditis)

• Polycythaemia

• Pulmonary oedema

Pulmonary hypertension and, eventually, right ventricular hyper-trophy may be seen where the shunt is left-to-right and some of the output of the left ventricle is recirculated through the lungs. The shunt may eventually reverse and then cyanosis develops.

General management

An obstetric ultrasound scan is often used to screen pregnant women at around 20 weeks for signs of CHD in their unborn babies. Most defects, however, are well tolerated in utero and it is only after birth that the impact of the anatomical and subsequently haemodynamic abnormality becomes evident. In young children, chest radio-graphy may show cardiomegaly. Electrocardiography (ECG) may demonstrate an abnormal cardiac axis, ventricular hypertrophy and strain, depending on the lesion present. CHD is more commonly diagnosed through echocardiography, which has superseded intracardiac catheter studies, and confirmed by cardiac magnetic resonance imaging (MRI).

Early correction of the congenital defect, often by transvenous catheter techniques, is the treatment of choice. More complex defects may require an operation. Medical treatment may be needed for the management of pulmonary oedema, heart failure, polycythaemia, infection or emotional disturbances. Modern surgical and medical care helps children survive into adult life and patients are then often said to have adult or ‘grown-up’ CHD. Nevertheless, complications observed in adults who were previously thought to have had successful repair of CHD include arrhythmias, valve disorders and cardiac failure, and residual defects can still predispose to complications such as infective endocarditis.

Dental aspects

All dental health-care professionals (HCPs) should be certified in basic cardiopulmonary resuscitation (CPR), and the entire team should rehearse emergency protocol procedures regularly (Ch. 1).

Patients with heart disease should take their medications as usual on the day of the dental procedure, and should bring all their medications to the dental surgery for review at the time of the first appointment. The most important aspect for dentists to consider is how well the patient’s heart condition is compensated. Patients with stable heart disease receiving atraumatic treatment under local anaesthesia (LA) can receive treatment in the dental surgery. Since cardiac events are most likely to occur in the early morning, patients with cardiac disease should be treated in the late morning or early afternoon. The dental team should provide dental care with a stress-reduction protocol and with good analgesia, limiting the dosage of adrenaline (epinephrine). An aspirating syringe should be used to give an LA, since adrenaline in the anaesthetic entering a vessel may theoretically raise the BP or precipitate arrhythmias. Gingival retraction cords containing adrenaline should be avoided. Conscious sedation, preferably with nitrous oxide, can be given with the approval of the physician. General anaesthesia (GA) is a matter for expert anaesthetists in hospital.

Congestive cardiac failure may complicate management. In cyanotic CHD there may also be polycythaemia-related bleeding tendencies caused by thrombocytopenia, platelet dysfunction, coagulation defects (from liver hypoxia – causing reduced vitamin K-dependent factors) and excessive fibrinolytic activity. Thus platelets may be reduced, and the haematocrit, prothrombin time (PT [and International Normal Ratio, INR]; Ch. 8) and activated partial thromboplastin time (APTT) increased. Occasionally, there is a thrombotic tendency. A special hazard in some CHD is the development of cerebral abscess, sometimes due to oral bacteria. Leukopenia may be a factor in some right-to-left shunts. There may be susceptibility to infective endocarditis. Oral abnormalities can be associated with cyanotic CHD and may include:

■ delayed eruption of both dentitions

■ positional anomalies

■ enamel hypoplasia – the teeth often have a bluish-white, ‘skimmed milk’ appearance and there is gross vasodilatation in the pulps

■ greater caries and periodontal disease activity, probably because of poor oral hygiene and lack of dental attention

■ after cardiotomy, the possible appearance of transient small, white, non-ulcerated mucosal lesions of unknown aetiology.

Congenital Heart Disease in Other Syndromes

Down syndrome

See Chapter 28.

Noonan syndrome

Noonan syndrome, usually an autosomal dominant trait, is characterized by CHD (the commonest cardiac lesions are pulmonary stenosis, septal defects and hypertrophic cardiomyopathy), short stature, unusual facies, chest deformity, learning disability, and cryptorchidism in males. Facial features may include an elongated mid-face, hypertelorism, retrognathia, a lower nasal bridge and nasal root, a wider mouth, a more prominent upper lip and low-set ears. Abnormal vision and hearing are common. Other associations include hepatosplenomegaly and an abnormal bleeding tendency associated with low levels of clotting factors (particularly XI and XII), and with cherubism, jaw giant-cell lesions and neurofibromatosis.

Hypercalcaemia–supravalvular aortic stenosis syndrome (Williams syndrome)

Williams syndrome comprises, in its rare complete form, infantile hypercalcaemia, elfin facies, learning disability and CHD. Most cases appear to be sporadic. These children may be sociable and talkative (‘cocktail party manner’). Hypercalcaemia typically remits in infancy but leaves growth deficiency, osteosclerosis and cranio- stenosis. Cardiovascular lesions include supravalvular subaortic stenosis or other abnormalities, and may contraindicate GA. Also, masseter spasm has been reported during GA with halothane and suxamethonium, but it is not malignant hyperthermia. Dental defects may include hypodontia, microdontia and hypoplastic, bud-shaped teeth. The upper dental arch may be disproportionately wide and overlap the lower.