The goal of therapy for bradycardia or tachycardia is to rapidly identify and treat patients who are hemodynamically unstable or symptomatic due to the arrhythmia. Drugs or, when appropriate, pacing may be used to control unstable or symptomatic bradycardia. Cardioversion or drugs or both may be used to control unstable or symptomatic tachycardia. ACLS providers should closely monitor stable patients pending expert consultation and should be prepared to aggressively treat those with evidence of decompensation.

/pdf/part-8-adult-advanced-cardiovascular-life-support-2010-344vtppnij.pdf

Part 8: Adult Advanced Cardiovascular Life Support 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care

This section of the 2010 AHA Guidelines for CPR and ECC addresses cardiac arrest in situations that require special treatments or procedures beyond those provided during basic life support (BLS) and advanced cardiovascular life support (ACLS). We have included 15 specific cardiac arrest situations. The first several sections discuss cardiac arrest associated with internal physiological or metabolic conditions, such as asthma (12.1), anaphylaxis (12.2), pregnancy (12.3), morbid obesity (12.4), pulmonary embolism (PE) (12.5), and electrolyte imbalance (12.6).

The next several sections relate to resuscitation and treatment of cardiac arrest associated with external or environmentally related circumstances, such as ingestion of toxic substances (12.7), trauma (12.8), accidental hypothermia (12.9), avalanche (12.10), drowning (12.11), and electric shock/lightning strikes (12.12).

The last 3 sections review management of cardiac arrest that may occur during special situations affecting the heart, including percutaneous coronary intervention (PCI) (12.13), cardiac tamponade (12.14), and cardiac surgery (12.15).

Asthma is responsible for more than 2 million visits to the emergency department (ED) in the United States each year, with 1 in 4 patients requiring admission to a hospital.1 Annually there are 5,000 to 6,000 asthma-related deaths in the United States, many occurring in the prehospital setting.2 Severe asthma accounts for approximately 2% to 20% of admissions to intensive care units, with up to one third of these patients requiring intubation and mechanical ventilation.3 This section focuses on the evaluation and treatment of patients with near-fatal asthma.

Several consensus groups have developed excellent guidelines for the management of asthma that are available on the World Wide Web: 

### Pathophysiology

The pathophysiology of asthma consists of 3 key abnormalities: 

Complications of severe asthma, such as tension pneumothorax, lobar atelectasis, pneumonia, and pulmonary edema, can contribute to fatalities. Severe asthma exacerbations are commonly associated with …

http://www.kardio.hu/feltoltott/dokumentumok/fajl_201148105352Cardiopulm_resuscit_Pt12_Cardiac_arrest.pdf

Part 12: Cardiac Arrest in Special Situations 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care

Intrauterine growth restriction.

The first haemodynamic change during pregnancy seems to be a rise in heart rate. Starting between two and five weeks this continues well into the third trimester. Stroke volume increases slightly later than the heart rate and continues throughout the second trimester after an augmentation of venous return and a fall of systemic vascular resistance and afterload. Myocardial contractility is probably slightly increased. During the third trimester there is relatively little change in these cardiac indices. After delivery there is a very early and dramatic reduction in volume loading followed by a return towards normal cardiac output. Structural changes within the heart reflect the volume loading of pregnancy and include dilatation of the valve ring and increase in myocardial thickness. Post partum resolution of the ventricular hypertrophy seems to take longer than the rest of the post partum changes. The resemblance to the cardiovascular changes associated with training and exercise are fascinating and worthy of further study.

https://heart.bmj.com/content/heartjnl/68/12/540.full.pdf

Adaptation of the maternal heart in pregnancy

SUlMMARY To assess the effects of a natural volume overload state (pregnancy) on left ventricular function we recorded echocardiograms each trimester (TM) and four to 12 weeks postpartum. Heart rate increased from 77 ± 2 (SEM) to 88 ± 2 heats/min (TM I vs TM 3, P < 0.01) and declined to 69 ± 2.0 beats/min postpartum (P < 0.05 vs TM 3). Despite these changes, end-diastolic dimension increased from 46.3 ± 0.7 to 50.7 0.7 mm (TM I vs TM 3, P < 0.01) and decreased postpartum to 47.5 ± 0.7 mm (P < 0.01 vs TM 3). Calculated stroke volume and cardiac index changed correspondingly, but ejection fraction, percent of fractional shortening and mean normalized rate of internal diameter shortening were not significantly altered. Left ventricular wall mass increased during gestation but decreased between TM 3 and postpartum 162 ± 8.3 vs 143 ± 6.2 g, P < 0.05). The ratio of posterior wall thickness to left ventricular radius decreased from 0.32 ± 0.01 to 0.29 ± 0.01 (TM I vs TM 3, P < 0.05), indicating progressive eccentric left ventricular enlargement. We conclude that a temporary volume overload state in normal humans results in hemodynamic adjustments often observed in cardiac decompensation (increased heart rate and size). However, left ventricular function, although not augmented, is wellpreserved, thereby leading to an increase in minute output. Thus, despite progressive left ventricular enlargement the shortening characteristics of the left ventricle remain unimpaired.

Edward N. Peterson

Papers

Maternal cardiovascular dynamics. IV. The influence of gestational age on the maternal cardiovascular response to posture and exercise.

Respiratory characteristics of maternal and fetal blood in cyanotic congenital heart disease