Treatable arrhythmias in cardiac arrests seen outside hospital

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LETTERS to the EDITOR

Treatable arrhythmias in cardiac arrests seen outside hospital arrhythmia, especially in the early stages of myocardial infarction, remains a leading cause of mortality in the UK. General practitioners (GPs) provide the initial medical care for most patients in the early stages of infarction and 5% of all victims experience a cardiac arrest in the presence of a GPP It is important to define the proportion of patients with rhythms likely to respond to treatment under these circumstances now that defibrillators are standard equipment in emergency ambulances and are being carried by increasing numbers of GPs. Since 1985, the British Heart Foundation has supplied over 200 defibrillator/monitors to GPs who provide details of the episode every time the machine is used. By October, 1991, 54 reports had been received where patients in the early stages of infarction experienced a cardiac arrest in the presence of a GP equipped with a monitor/defibrillator. The frequency of the arrhythmias recorded and the results of resuscitation are shown in the table. The results show that most patients with myocardial infarction who arrest in front of their doctor have an eminently treatable arrhythmia (VF or VT in 80% of cases). These patients were usually monitored after the clinical cardiac arrest so VT may have deteriorated into VF in the time taken to institute monitoring. However, the lack of reports of preceding tachycardia and the infrequency of VT (only 2 cases) suggest that VF is the commonest fatal arrhythmia in the early stages of infarction (as it is in patients monitored later on the coronary-care unit). 23 (53%) patients out of 43 with VF or VT survived; no patient with asystole or EMD was resuscitated. The high frequency of these prognostically favourable rhythms at the time of collapse emphasises the importance of responding rapidly to cases of possible infarction so that a defibrillator may be brought to the patient, preferably before cardiac arrest. We conclude that death from acute myocardial infarction in the community is due in most cases to treatable arrhythmia. The medical help available in these circumstances is likely to be a GP or the ambulance service. We report an excellent rate of successful resuscitation by GPs, and Cobbe et aP have reported comparable figures from an ambulance service (33% of patients surviving if VF developed after arrival of the ambulance).3

SIR,-Sudden

cardiac death trom

RHYTHM IN 54 CASES OF CARDIAC ARREST WITNESSED BY GP P AND RESULTS OF RESUSCITATION

The implication is clear-all who attend patients in the early stages of infarction should be able to defibrillate. Court Road Surgery, Malvern WR14 3BL, UK

M. C. COLQUHOUN

British Heart Foundation, London W1

D.

1. Pai

G. JULIAN

GR, Haites NE, Rawles JM. One thousand heart attacks in the Grampian: the place of cardiopulmonary resuscitation in general practice. Br MedJ 1987; 294: 352-54.

Rawlings DC. Study of the management of suspected cardiac infarction by British immediate care doctors. Br Med J 1981; 282: 1677-79. 3. Cobbe SM, Redmond MJ, Watson JM, et al. Heartstart Scotland: initial experience of national scheme for out of hospital defibrillation. Br Med J 1991; 302: 1517-20. 2.

Cholera and the environment SiR,—For 30 years the search has gone on for an environmental reservoir for cholera, to help explain seasonal oscillations. Dr Ventura and colleagues (April 11, p 937) demonstrate that the growth of Vibrio cholerae non-Ol on plant samples in sewage lagoons is associated with the seasonality of cholera in Peru. Colwell and her colleagues have also detected V cholerae 01on marine life, in non-culturable, viable states/ and have demonstrated that this reservoir is sensitive to environmental changes. Under unfavourable conditions, cholera bacteria become dormant, re-emerging to an infectious state with warming and nutrient availability. "Hibernating" forms of V cholerae coexist with a wide variety of algae and plankton/,3 which are also responsive to changes in temperature, pH, salinity, and nutrition. Climatologists report unusually large algae and plankton blooms at sea, and plankton sampled in the harbour near Lima, Peru, are contaminated with V cholerae.4 Phytoplankton and algae help modulate our climate.s They absorb atmospheric carbon (2 of the 7 billion metric tons released annually) and give off oxygen through photosynthesis; they scatter heat and light; and, through emission of volatile dimethylsulphide, help seed rain clouds. Marine plants are thus "fertilised" by atmospheric CO2 and by warming, and atmospheric CO2 is increasing (now about 350 parts per million), mainly from fossil fuel combustion. Pacific waters began warming in late 1990.6 V cholerae 01, biotype El Tor, serotype Inaba, may have arrived in the Americas with the bilge or ballast of a Chinese freighter,7 and Dr Faruque and Dr Alberts’ studies with DNA probes (Mar 21, p 740) suggest "genetic identity" for the strains causing epidemics in Bangladesh and the Americas. The unexpected intensity of the outbreak, which penetrated cities and towns along the Pacific coast in January and February, 1991, is consistent with multiple entry points from marine life blooms, with fish, molluscs, and crustacea as vectors. The internal dissemination throughout South and Central America reflects the vulnerability of host defences, inadequacies in sanitation, clean water, and fuel supply; and uncontrolled urbanisation (eg, Lima’s shantytowns) generated by the economic collapse of the 1980s. There is now convincing evidence for an environmental reservoir for cholera. Alterations, due to climatic change, in the distribution