Special Care Dentistry- Cardiovascular system
04 May 2011
The cardiovascular system relates to the heart and blood vessels. Blood is made up of plasma, red and white cells and platelets. Plasma contains proteins and other components responsible for the functions of blood. Defects that are specifically related to cell numbers are:
- Anaemia (too few red blood cells)
- Polycythaemia (too many red blood cells)
- Leucopenia (too few white blood cells)
- Leucocytosis (too many white cells)
- Thrombocytopenia (too few platelets)
- Thrombocythaemia (too many platelets)
What causes Anaemia?
Anaemia is caused by either a failure of the body to make sufficient red blood cells, e.g. bone marrow aplasia (aplastic anaemia) or bone marrow hyperplasia (iron deficiency anaemia). Alternatively, anaemias are known by the effect on the size and shape of the red blood cells, e.g.:
- Normochromic and normocytic (normal)
- Hypochromic and microcytic (pale and small)
- Normochromic and macrocytic (colour normal and large cells)
Acute blood loss, diseases such as tuberculosis and rheumatoid arthritis and problems related to bone marrow such as leukaemia can cause normocytic anaemias. Patients suffering from normocytic anaemia appear pale and complain of feeling tired and having no energy. They may also feel dizzy, experience breathlessness on exertion and ringing in the ears. Memory may also be affected. To treat this type of anaemia, the root cause must be identified and managed whilst treating with blood replacement.
Microcytic anaemias occur as a result of faulty haemoglobin production, usually due to iron deficiency. Haemoglobin is responsible for carrying oxygen around the body. Patients suffering from microcytic anaemia experience tiredness, breathlessness, and report palpitations, dizziness and poor memory. They also appear pale and have a rapid pulse. Microcytic anaemia is a concern for patients requiring a general anaesthetic for their dental treatment because the oxygen-carrying capacity of the blood is reduced. Macrocytic anaemias occur due to a deficiency of vitamin B12 and folate, both of which are needed to make white blood cells and platelets. Patient suffering from this type of anaemia do not have the secretion of intrinsic factor in the stomach wall which combines with the extrinsic factor (vitamin B12) and so the deficiency follows. Treatment is simple however, with the use of vitamin B12 injections. Haemolytic anaemias are seen when there is a premature destruction of the red blood cells in congenital conditions such as sickle cell trait/disease and thalassaemia, where the haemoglobin is defective.
Blood dyscrasias basically refers to a blood disorder or problems with the organs that make blood components. It can either be inherited or acquired and it is important to decide from looking at a patient’s medical history which of the two it is. It is really important that we are aware of blood disorders in dentistry, especially when it comes to tooth extractions. These disorders include:
- Coagulation (forming of a blood clot)
- Platelet disorders
- Vessel wall defects
- Haemophilia A
- Haemophilia B
- Haemophilia C
- Von Willebrand’s disease
- White blood cell defects such as raised white cell counts (leucocytosis), reduced white cell counts (neutropenia) and Neoplastic disease
The most common types of Neoplastic disease are the lymphomas and leukaemias. Lymphomas are malignant overgrowth of lymphoid cells, lymph glands, spleen and liver and are divided into:
Hodgkin’s disease/lymphoma- usually seen in young men, the first sign may be enlarged lymph nodes in the neck. Signs of anaemia, thrombocytopenia and Neutrogena may also be present. Radiotherapy and chemotherapy are usually used to treat patients. The five year survival rate is approximately 60%.
Non-Hodgkin’s lymphomas- these are more common and have many sub-types, they are also more likely to affect older people as their prevalence increases with age. Signs and symptoms are very similar to Hodgkin’s disease and treatment depends on the type of lymphoma however chemotherapy is still used to treat patients. Patients with low grade lymphoma can survive for many years after.
Leukaemias are a group of diseases and chromosome defects (chronic myeloid) are sometimes responsible. Radiation can also be a cause. Leukaemia is characterised by extra numbers of normal, precursor cells in the bone marrow. They are classified into acute and chronic and according to the cell type affected: myeloid or lymphoblast/lymphatic. Anaemia occurs in patients in which crowding out of the bone marrow with the precursors of abnormal white blood cells occurs. The different types of leukaemia are:
- Acute lymphoblast leukaemia- usually children, 95% five-year survival rate
- Acute myeloid- adults mainly affected
- Chronic lymphatic- middle-age normally affected
- Chronic myeloid- most common in old-age
The general signs and symptoms are:
- Anaemia due to reduced production of red blood cells
- Excessive bleeding due to reduced platelet production
- Susceptibility to infections because of reduced normal granulocyte production
- Infections-many are treated with radiotherapy and chemotherapy, some with bone marrow transplantation
The oral signs and symptoms are:
- Anaemia- causes pale gums
- Gingival hypertrophy (enlargement) due to an inability to fight infection
- Ulceration due to altered immunity and sometimes the use of cytotoxic drugs
- Infections such as oral herpes (viral) and Candida (fungal)
- Bleeding tendency- gingival oozing, prolonged bleeding post-treatment and purple/blue patches on soft tissues
- Xerostomia (dry mouth) and caries as a consequence
- Dysphasia (difficulty swallowing) because of the lack of saliva
- Cervical lymphadenopathy (swollen lymph glands in the neck)
Cardiovascular disease can be broadly subdivided into the following categories:
- Congenital heart defects (CHD) Genetic CHD include Down’s syndrome (septal defects), osteogenesis imperfecta (aortic and valve defects). Environmental CHD include rubella (septal defects and pulmonary valve/artery defects)
- Ischaemic heart disease- angina pectoris, myocardial infarction (heart attack)
Oral and dental considerations in CHD are antibiotic prophylaxis, anaesthesia, bleeding, delayed eruption and enamel hyperplasia.
Anaesthesia considerations in CHD are:
- General anaesthesia- risk of arrhythmias, myocardial disease and conditions treated with digoxin
- Relative analgesia (nitrous oxide inhalation sedation)- may be positively helpful with management because of superior levels of oxygen delivered during inhalation sedation (at the very least 30%, compared with 21% in room air)
- Local analgesia- avoid epinephrine in patients with myocardial disease, arrhythmias and Tetralogy of Fallot (most common heart defect in children)
CHD and bleeding:
- Patients may have warfarin after replacement valve surgery
- Aspirin for shunts
- Streptokinase for cardiac catheterisation
- Defective platelet function (cyanotic heart disease)
- Increased fibrinolytic activity (cyanotic heart disease)
CHD and dental procedures:
- Development of infective endocarditis
Infective endocarditic results from organisms settling on a pre-existing lesion, e.g. faulty valve. In the UK, the National Institute for Health and Clinical Effectiveness (NICE) now recommends that antibiotic prophylaxis is not given prior to dental treatment in patients who previously were thought to be at risk of developing infective endocarditic due to the type of heart defect that they had. The use of chlorhexidine mouthwash prior to dental treatment is no longer recommended. The evidence linking infective endocarditic and dental procedures is weak and NICE concluded that the risk of anaphylaxis from antibiotic use was greater than the risk of developing infective endocarditic.
The treatment of anaphylaxis (severe allergy reaction) involves calling for emergency help, maintaining the airway, raising the legs to increase blood pressure, administering oxygen and 0.5mg of 1:1000 epinephrine at 10 minute intervals and intravenous hydrocortisone 100mg until resuscitation help arrives. The primary concern of the dental nurse is to call for an ambulance and make sure that the necessary oxygen and drugs are at hand as well as working as part of a team.
This is a temporary chest pain when there are increased demands on the heart and arises as a result of lack of blood flow when the coronary arteries are narrowed by atherosclerosis. A heart attack may follow if the patient is not treated. It is important to know the history of the disease, frequency of attacks and also factors which can trigger off attacks. Appointments should be made short and if the patient is stressed then the dentist may recommend the patient takes a nitro-glycerine tablet or use a spray before the appointment.
MI, or “Heart attack” occurs when a plug of platelets and fibrin block off a coronary vessel producing an area of infarction (loss of blood supply) to the heart muscle. The piece of heart muscle supplied effectively dies. The signs are the same as for angina but more severe and are not helped by resting or the usual drugs. Dentists should consult with the patient’s physician as to the extent of heart muscle damage and precautions about future dental care such as the use of drugs. If the MI is recent then it is advisable to postpone elective procedures, especially under GA as a repeat MI is likely to happen again.
Hypertension is defined as a systemic arterial pressure that is consistently raised above average. The result of persistently raised blood pressure can be a stroke or heart failure. In most cases, the cause is unknown however lifestyle factors such as smoking, obesity and stress can often contribute. Medication is the usual treatment for hypertension.