Cardio-vascular diseases comprise heart diseases (e.g. coronary heart disease, cardiac insufficiency, cardiac arrhythmia) and circulatory disorders (e.g. arterial hypertension/ hypotension, stroke, acute obliteration in the limbs, pulmonary embolism, venous disorders). Severe chronic cardiac problems such as chronic heart failure are relatively seldom. This is obviously due to pre-employment examination and repeated medical fitness tests in the merchant marine service. Most of the life-threatening cardiac events on board are caused by acute ischemic cardiovascular diseases (CVD). Among CVD, the coronary heart disease plays a predominant role
Coronary heart disease
Hammar et al. (20) found in nautical officers a 1.9 times increased risk of myocardial infarction. According to Ehara et al. (2), among Japanese officers in particular captains showed a high prevalence of CVD (16.3%). Out of the above mentioned 11,325 Polish seamen (1985 – 1994), 109 ones had a myocardial infarction at sea; they consisted of 20 nautical officers or captains, 18 engine room officers, 33 able bodied seamen, 26 crew ranks of the engine room and 9 galley staff members (5).
Increasing age leads to a lack of blood vessel’s elasticity and to a calcium deposit that can accumulate on their inner walls. Also coronary blood vessels are affected by this process and become narrower. In case of acute pain of the chest (angina pectoris) as an early stage of myocardial infarction the coronary arteries are narrowed but not altogether blocked. In acute overexertion the heart workload increases and the heart muscle becomes short of blood resulting in typical angina pectoris symptoms.
If a blood clot completely blocks a coronary artery the respective blood and oxygen supplying area of the heart muscle dies as a sign of myocardial infarction.
CHD poses the commonest heart disease in people over 50 years of age but can also happen in younger people especially in coincidence with metabolic disorders.
Acute CVD symptoms are characterized by dull and oppressive pains predominantly in the left half of the chest often radiating out in the shoulders, the left arm or in the neck and lower jaw. Atypical symptoms may occur and be highly variable e. g. sweating or weakness and anxiety. CVD symptoms may be elicited by strong physical activity.
In case of severe chest pain of a seaman the officer responsible for shipboard medical care (“health officer”) has to immediately check the patient’s pulse rate and heart rhythm. The differential diagnosis of chest pain must include ruptured aorta, embolism, pneumonia, pleurisy, pneumothorax or shingles. The medical assistant service should be directly contacted for further consulting, location of pain should be asked, physical examination be done, information about preexisting symptoms or cardiac incidents, age, smoking habits, presence of diabetes mellitus, history of heart disease in the family be gathered and possibly an early evacuation be intended.
Nowadays, it is possible to diagnose damage to the heart muscle by on the spot quick-tests (Tropinin-test) suitable also for the use by trained, non-medical persons like seamen. Further, the seaman’s ECG which can be transmitted to the telemedical assistant service provides worthwhile information about the cardiac rhythm of a patient with unspecific thoracic complains. Since the benefit of treatment for myocardial infarction is reduced after only a few hours delay quick diagnosis of CVD maybe life-saving. Thus, some flag-states have already implemented the Tropinin-test and/ or an ECG device (as a part of a semiautomatic defibrillator) in their statutory medical chest. The Tropinin-test and the ECG are of particular importance in the decision to administer anti-thrombotic substances such as acetylsalicic acid respective medicines for heart arrhythmia (Verapamil).
First of all, the seaman with chest pain is advised to stay in bed except to go to the toilet. According to medical advice acetylsalicic acid, nitrolingual spray, metropolol, diazepam and a strong pain-killer (preferably morphine) should be administered if available on board. Further, oxygen should be given through a mask. The patient’s current clinical status should be continuously observed by a crew member until professional aid arrived on the vessel. If the patient is conscious “the heart position” (sitting half-upright, back supported by a pillow, legs hanging) should be taken. The continuous monitoring of an ECG and its transmission ashore to the medical assistance centre is very helpful.
Acute unconsciousness often indicates a life-threatening arrhythmia, a severe cardiac failure or even a cardiac arrest. In such cases only the immediate cardio-pulmonary resuscitation, ideally in association with a semiautomatic defibrillator, is life-saving.
On board of merchant ships usually a health officer as a medical layman holds the responsibility for medical care. Thus, the diagnoses and treatment at sea mainly depends on his experience. His first-aid measures rely on his medical training which often took place several years ago. This training should qualify the seaman to check and to control basic cardiac parameters such as heart frequency and blood pressure as well as to cope with the resuscitation technique according to updated, currently valid first-aid recommendations.
The prognosis of a coronary event at sea is different from that ashore. This is mainly due to limited primary medical care aboard. For example, the mortality rate of myocardial infarction among Polish seafarers was similar to that of the general Polish population in spite of the expected healthy-worker effect of seamen (only 24.5% of subjects with a myocardial infarction at sea survived one year) (5); it is assumed that the survival after a myocardial infarction at sea might be less favorable than that ashore due to a lack of early intervention as angioplasty or lysis. Further reasons for the worse prognosis after a myocardial infarction at sea might be that the team of rescuers on board is often inexperienced, the rescue/resuscitation action is frequently delayed, and the evacuation ashore is often difficult or impossible.
The CHD prognosis mainly depends on the fast and correct diagnosis. In case of unspecific thoracic symptoms, the causes should be identified first. Due to the often unclear genesis of symptoms (cardiac, pulmonary or orthopedic), a competent medical evaluation is necessary. Since seamen are in general not capable of doing this, they need (telemedical) advice by a physician ashore.
Cardiac failure can occur as a consequence of survived heart attack, of longstanding untreated hypertension, of congenital valvular defect, of (viral) myocarditis or of alcoholic disease.
The patients suffer from dyspnoea after slight effort, raised and often irregular pulse, lack of physical capacity, blue lips, swollen feet and lower legs. They should be advised to have physical rest in an upright sitting posture. According to medical advice oxygen, nitro drugs or drugs for water excretion may be administered before hospital treatment.
Febrile infections with a life-threatening inflammation of the heart muscle, heart infarction, congenital factors or severe hypothermia can lead to dangerous arrhythmia. The latter can result in a fall of blood pressure, faintness and some patients may suffer from shortness of breath. Many patients develop palpitations and the feeling that their heart has stopped. Sometimes these symptoms are accompanied by chest tightness, dizziness, unconsciousness or light-headedness
Cardiac arrhythmia treatment
The patient’s pulse as well as blood pressure should be permanently controlled. (For the seamen it might be demanding to judge the cardiac rhythm especially at high heart frequency. Feeling the pulse and measuring blood pressure are important findings for making a diagnosis and this needs to be trained.)
If the cardiac palpitations persist the patient should rest in bed with slightly raised upper body and legs low until the symptoms disappear. Medical advice should be sought with a view to evacuation, especially in case of a rapid or irregular pulse rhythm or if symptoms like chest tightness, pain in the chest or episodes of unconsciousness occur during palpitations.
In case of potentially arrhythmic heart diseases a definitive medical advice is scarcely possible without knowing the patient’s ECG. Drugs for cardiac arrhythmias used wrongly can intensify or even elicit abnormal heart rhythm. Thus, it may be dangerous to administer drugs without noticing the patient’s cardiac rhythm. According to the International Medical Guide of Ships (3rd edition) the rescuer should give metoprolol to patients with palpitation if medical advice cannot be obtained.
In suspected cardiac arrhythmia a telemedical transmitted ECG is of great value -provided that the vessel is equipped by additional medicines for heart rhythm disturbance (verapamil, atropine). At present, the discharge and transmission of an ECG can be realized via semi-automatic defibrillators operated by laymen. In addition to shock treatment during ventricular fibrillation (accounting for 80% of sudden cardiac deaths), defibrillators can take on the medically helpful function of telemedicine at sea. By means of the transmitted ECG it is possible for the physician ashore to diagnose cardiac arrhythmic disorders and to advise anti-arrhythmic drugs available on board. It should be mentioned that the relevance and the cost-benefit ratio of semi-automatic defibrillators are controversially discussed among practitioners in maritime medicine.'