Introduction

Treating patients with co-existing cardiovascular disease (heart problem) often causes concern over potential problems during dental treatment. The high incidence of heart problem in the population, makes it the most common medical problem encountered in dental practice. Additionally, the increasing survival of children with congenital heart disease makes them a significant proportion of those attending for dental treatment. These patients are at risk for bleeding, infective endocarditis (inflammation of the inner lining of the heart), drug action and interaction, and the patient’s decrease ability to tolerate the stress and trauma associated with dental treatment.

Related heart problem

The potential related heart problems that a dental practitioner is likely to encounter can be listed as follows:

1. Ischaemic heart disease
2. Hypertension (high blood pressure)
3. Dysrhythmias (irregularity of the heart beat) and pacemakers
4. Valvular heart disease
5. Anticoagulants (pharmaceutical product that inhibits the formation of blood clot) and heart-related drugs
6. Congenital heart disease

Potential complication

Ischaemic heart disease.

Ischaemic heart disease is common in the general population and thus, is common in dental practice. It is in the form of heart failure or angina (chest pain).Heart failure describes the inability of the heart to provide a cardiac output(the amount of blood that can be pumped out from the heart) sufficient for metabolic needs. It is common, particularly in the elderly and the underlying cause is usually coronary artery disease or hypertension.

Angina affects around 1% of the population, the prevalence increasing with age. It is usually caused by coronary artery disease, and anginal pain is precipitated when there is an inadequate supply of oxygen to the myocardium (heart muscle). Anginal pain is often felt in the mandible (lower jaw), with secondary radiation to the neck and throat. The dental environment increases the likelihood of an anginal attack because of associated fear, anxiety or pain. Anginal pain is transient. Prolonged chest pain may suggest myocardial infarction. Minor dental interventions seem to be well tolerated by patients with recent uncomplicated myocardial infarction (heart attack), but more complex treatments warrant special consideration, particularly if heart failure or dysrhythmias complicated the infarct. Hospital consultation may then be appropriate. If general anaesthesia is being considered, there are certain clinical features which make it a significant risk. These include myocardial infarction within the previous 6 months, signs of heart failure and a history of rhythm disturbances. It is best not to do dental extractions within six months of myocardial infarction.

Hypertension.

The stress of a dental visit may artificially raise the blood pressure. An increase in mean heart rate and blood pressure can be induced both by anticipation of and the actual dental treatment itself. Similar significant changes are also seen before a local anaesthetic is administered, during restorative treatment and extractions. Although these effects are usually within normal physiological variation, they may be exaggerated in any patient with cardiovascular disease, and particularly those with hypertension.

Dysrhythmias and pacemakers.

A dysrhythmia describes any abnormality in the rate, regularity or site of origin of the heart impulse, or where there is a disturbance in the conduction of that impulse such that the normal sequence of atrial (the upper compartment of the heart) and ventricular (the lower compartment of the heart) activation is altered. Whatever the aetiology, any rhythm disturbance may lead to a reduction in the efficiency of the heart pump. Cardiac / heart dysrhythmias are well recognized during oral surgery, especially during extractions or pre-prosthetic surgery under local anaesthesia. The duration of rhythm disturbance is usually short, cardiac output is maintained, and it is normally of little consequence. Patients treated with digoxin for atrial fibrillation or congestive heart failure are more prone to rhythm complications during dental extractions than other heart patients.

Modern cardiac/heart pacemakers are complex but are usually tolerant of most external insults. If the units are functioning normally pre-operatively, they are likely to continue to do so during dental treatment.

Valvular heart disease.

Any heart valve lesion can impair the circulation, ultimately resulting in heart failure. Such lesions are either obstructive (stenotic), or incompetent (regurgitant), and most abnormalities affect the aortic and mitral valves. Despite the decline in rheumatic fever, valvular heart disease remains a common and important pathology.

Many degenerating valves require operative therapy, which may involve valve reconstruction or valve replacement, using tissue or mechanical prostheses. Mechanical prostheses are very durable, but they require life long anti-coagulation to reduce the risk of thrombo-embolism (the formation of blood clot) or of thrombosis of the valve itself. The degree of anti-coagulation needed to protect against thrombo-embolism varies with the type of prosthesis and this is particularly significant when considering dental treatment.

There are two main concerns during dental treatment of patients with valvular disease, that is, the risk of infective endocarditis and the risk of bleeding in anticoagulated patients.

1. Infective endocarditis (inflammation of the inner lining of the heart) is a rare, but a potentially life-threatening disease that can occur when bacteria from plaque is released in to the bloodstream. This can happen during brushing teeth and flossing, and also during certain dental procedures. Oral bacteria for example, streptococcus sanguis can enter the bloodstream and adhere to damaged heart tissues or valves. The most important goal of dental therapy in patients with valvular heart disease is the need to prevent infective endocarditis. Most cases of infective endocarditis involving oral microorganisms probably are caused not by dental treatment, but by dental disease, mastication and oral hygiene procedures.
2. The risk of bleeding in patients with prosthetic/artificial heart valves; other valvular disorders; or a history of myocardial infarction, or thromboembolism frequently receive anticoagulant therapy consisting of coumadin derivatives, such as dicumarol and warfarin. Apart from Warfarin, aspirin and other anti-platelet agents (pharmaceutical product which interferes with the function of platelets, in the formation of blood clot eg Persantin, Clopidrogel (Plavix), Ticlopidine (Ticlid)) are commonly prescribed for many heart disorders, and may also cause prolonged bleeding and this should be taken into account before any surgical procedures are undertaken . Without the anticoagulant medications, these patients are at high risk for blood clot development.

Congenital heart disease.

Congenital heart disease, for example atrial or ventriculo septal defect, is one of the most common developmental anomalies. While many such conditions are apparent in the neonate, a significant proportion do not come to light until the child is older, or even later on in adult life. Patient with congenital heart disease require special care dentistry because of their susceptibility to infective endocarditis.

Management

The primary management goal for the patient with heart disease during dental therapy is to ensure that any hemodynamic change produced by dental treatment does not exceed the cardiovascular reserve of the patient. This is best achieved by minimizing any hemodynamic alterations during treatment (that is, by maintaining the patient’s optimum blood pressure, heart rate, heart rhythm, cardiac output and myocardial oxygen demand). Psychological and physiological stress during dental treatment has the potential to significantly alter hemodynamic stability. Consequently, a stress-reduction protocol is frequently suggested for patients with significant cardiovascular compromise, which includes:

1. shorter appointments, preferably in the morning when the patient is well-rested and has a greater physical reserve
2. Use of profound local anesthesia to minimize discomfort
3. Pre-operative or intraoperative conscious sedation or both
4. Excellent postoperative analgesia.

Psychological or physiological stress may exacerbate symptoms of ischemic heart disease. The use of a stress-reduction protocol and profound anesthesia is an integral part of dental treatment for these patients. Dental treatment planning may be altered in these patients by the need for shorter appointments, use of only small amounts of vasoconstrictor in local anesthetics and possible indications for preoperative or intraoperative conscious sedation. Supplemental oxygen delivered via a nasal canal may help prevent intraoperative anginal attacks.

The use of local anesthetic agents (pharmaceutical products to numb a nerve) with vasoconstrictors (pharmaceutical product which causes local constriction of blood vessel) in patients with cardiovascular disease remains controversial. The most commonly used vasoconstrictor is adrenaline. Normal adrenaline release from the adrenal medulla can increase 20- to 40- fold during stress. Such stress may be induced by pain during dental treatment. Patients receiving local anesthetic without vasoconstrictor often have significantly impaired pain control compared with those receiving local anesthetic with adrenaline.For this reason, patients with cardiovascular disease may be at greater risk of experiencing massive endogenous adrenaline release secondary to poor local anesthesia than they are from the small amount of vasoconstrictor used in local anesthetics.

Patients with cardiac dysrhythmias may require special precautions during dental therapy. Antidysrhythmic drugs commonly are used, many of which have side effects such as gingival overgrowth or xerostomia (dry mouth) . The use of local anesthetics with vasoconstrictors may be contraindicated in patients with refractory dysrhythmias; dental treatment may best be accomplished in a controlled medical setting with careful cardiac monitoring. Some dysrhythmias are treated with implantable pacemakers or automatic defibrillators in addition to drug therapy. Pacemakers and automatic defibrillators present a low risk of infective endocarditis and do not require prophylactic antibiotic coverage before dental therapy. Older pacemaker models were unipolar and could be disrupted by equipment that generates an electromagnetic field. Diathermy is the main concern as it can interfere with pacemaker function. Other electric and electro-mechanical signals can interfere with pacemaker function, such as electronic apex locators, ultrasonic scalers, and even ultrasonic cleaning baths. However, electric pulp testers and dental hand pieces appear to be safe.

Since dental procedures that involve bleeding may induce a transient bacteremia, antibiotic prophylaxis is recommended prior to the dental procedures. Dental antibiotic prophylaxis is the administration of antibiotics to a dental patient for prevention of harmful consequences of bacteremia, that may be caused by invasion of the oral flora into an injured blood vessel during dental treatment. As a local adjunct to systemic antibiotic prophylaxis, a chlorhexidine mouthrinse has been recommended before dental procedures. Dental antibiotic prophylaxis is recommended for those with

1. Artificial heart valves
2. Previous infective endocarditis
3. Complex cyanotic congenital heart disease
4. Surgically constructed systemic pulmonary shunts
5. Mitral valve prolapsed with valvular regurgitation

Dental procedure, where bleeding is anticipated, and require antibiotic prophylaxis can be categorized as follows:

1. Extraction of a tooth
2. Placement of a dental implant
3. Reimplantation of tooth
4. Periodontal procedures (scaling and surgery)
5. Intraligamentary local anaesthetic injection
6. Root canal procedure
7. Initial placement of orthodontic bands but not the bracket

However recent findings from National Institute for Health and Clinical Excellence UK recommends that antibiotic prophylaxis solely to prevent infective endocarditis should not be given to people at risk of infective endocarditis undergoing dental and non dental procedures. (NICE Clinical Guideline 64, March 2008)

Patient with prosthetic valves should not discontinue their anticoagulants without consulting their cardiologist. Mechanical mitral valves are prone to thrombosis, which cause emboli if adequate anti-coagulation is not maintained, although short term modification may be possible.

Drug interactions with warfarin and other similar agents are numerous, and these must be considered. Aspirin and other non-steroidal anti-inflammatory drugs may dramatically increase the risk of warfarin-associated bleeding. Tetracyclines may decrease vitamin K production, interfere with formation of prothrombin and increase anticoagulation. Metronidazole may inhibit coumadin’s metabolism, potentiating its anticoagulant effect, while penicillin may counteract coumadin’s effect.

Referrence:

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Organization:

1. Malaysian Association of Oral and Maxillofacial Surgeon.
2. Malaysian Dental Council.
3. Malaysian Dental Association.