2The HeartFour-chambered organ located in the upper left thoracic cavityPurposePumps the blood around the body so that oxygenand nutrients can be distributed to all areas of thebodyMaintains the blood pressure at an acceptable levelGenerates and conducts electrical impulsesHeart rate is controlled by the autonomic nervoussystem
3The Heart Main pacemakers of heart: Sinoatrial node: bpm; primary pacemakerAtrioventricular node: Connects atria and ventricles; bpmBundle of His and Purkinje fibers: carry electrical impulses from AV node to complete ventricle rate pacing; bpm
4Cardiac medicationsIncrease /decrease the force of the myocardial contractionIncrease / decrease the heart rateIncrease / decrease the conduction of electrical impulses through the myocardium
6Cardiac GlycosidesDerived from natural sources; treatment for heart failure:cardiac distention-inability to pump the full blood volumecardiac hypertrophy-prolonged stretchingsodium and water retention-decreased renal blood flowResults in weight gain, edema, shortness of breath, and pulmonary congestion
7Digoxin Decreases electrical conduction Negative Dromatotropic Effect Increases time spent in diastoleIncreases the force of the myocardial contractionPositive inotropic actionEnd result: slows and strengthens contractions
8Digoxin: Dose Considerations Duration of actionMethod of administrationOtherPhysical size of the clientOther medicationsRenal or hepatic functionAdvanced agePresence of other illnesses
9Digoxin Low therapeutic index Toxicity can be life-threatening; occurs in 10-20% of patientsMany drug-drug, drug herbal interactionsRoutine monitoring of serum potassium and digoxin levels
10Digoxin: Adverse Effects Gastrointestinal effectsNausea and vomitingAnorexiaDiarrheaCardiac effectsCardiac arrhythmiasNeurological effects
11Cardiac Glycoside Toxicity Predispose to cardiac glycoside toxicityHypokalemiaRenal impairmentRapid IV administration
12Cardiac Glycoside Toxicity TreatmentStop the drugPhysical assessmentCheck potassium levelAdminister if neededMonitor heart rateAdminister antiarrhythmics
13Nursing Considerations Apical pulse for 1 minute. Hold if HR < 60 bpmReport changes in heart rhythmAssess for symptoms of toxicityMonitor digoxin blood levelsMonitor for drug-drug and drug-herbal interactionsEducate : signs of toxicity and how to monitor pulse rate.
14Antiarrhythmic and Antidysrhythmic Drugs Grouped together according to their similar actionsWork three ways:Decrease automaticity of cardiac tissues in the ectopic sitesAlter rate of conductionAlter refractory period of cardiac muscle between consecutive contractions
15Antiarrythmic Agents Dependent on: type of dysrhythmia presence of other conditionssafety of the drugonset and/or duration of drug actionAdministered IV until patient stabilized, then oral agents givenArranged into classes
16Antidysrhythmic Medications Class 1 (1A, 1B, 1C): decrease the influx of sodium ions, stabilizing membranesClass 2: decrease contractility, B/P, AV node conductionClass 3: Prolong action potential, refractory periodClass 4: Decrease myocardial contractility, 02 demand
17Antidysrhythmics Quinidine gluconate – Class 1 Lidocaine – Class 1B Dilantin – Class 1BPropranolol – Class 2Verapamil HCL – Class 4Digoxin – Class 4
18Adverse Effects GI upset Cardiovascular disorders Hypersensitivity HypotensionBradycardiaLightheadedness
19Nursing Considerations Take patients apical pulse for one minuteRecord rate and rhythm of the heartbeatAssess allergiesMonitor blood pressurePatient should be supine when administering IV agents.
20Beta-adrenergic Blocking Agents Block the hormone epinephrineInhibit beta and beta2 sympathetic receptorsReduce heart rateReduces contractilitySlow electrical conductionDecrease the blood pressure
22Calcium Channel Antagonists Reduce the influx of calcium into the cell:Prevention of reversal of spasms of the coronary blood vesselsCoronary artery dilationReduction of myocardial oxygen consumptionExample: Verapamil.
23Adverse Effects Vasodilation may cause: Hypotension Edema Dizziness HeadacheSlower myocardial conduction may cause:BradycardiaHeart failureOther effects:Constipation, diarrhea, nausea, fatigue
24Patient Education Ensure understanding of drug regime Review signs to report to their health care providerInstruct patient how to take their pulseRemind them of the importance for proper follow-upEncourage questions