Introduction

Congestive Cardiac Failure Patient

Despite significant advancements in pharmacological therapy, mortality continues to remain high in patients with congestive heart failure (1). Much attention has been paid to optimization of pacing modalities for patients with left ventricular dysfunction when ventricular pacing is required. Patients with congestive heart failure frequently have symptomatic chro-notropic incompetence, sinus node dysfunction, or atrioven-tricular block, all of which are class I indications for cardiac pacing...

Info

Influence of temperature on myocardial metabolism. Although it is expected that hypothermia decreases myocardial oxygen consumption in the beating and fibrillating heart, there also exists a significant difference between the normothermic and hypothermic arrested heart. This indicates that the heart still has a measurable oxygen demand while arrested. Also notable is the difference in myocardial oxygen consumption between the fibrillating and arrested heart at either temperature. Fig....

Genes In The Remodeling And Recovery Of The Failing Human Heart

To illustrate the use of genomics tools in cardiovascular research, the last section of this chapter introduces a human heart failure project involving the use of a microarray-based approach. The goal of this project is to utilize microarrays to identify candidate genes that are uniquely regulated in the hearts of patients who have recovered from severe end-stage heart failure. The patient cohorts utilized in this study are patients in end-stage heart failure who require a left ventricular...

Companion Cd

Chapter 16 Mechanical Aspects of Cardiac Performance jpeg 1 Monitor display of electrocardiogram, blood pressures, and SvO2. jpeg 2 Cannulation of a peripheral artery. jpeg 3 Cannulation of a peripheral artery. jpeg 4 Pressure transducer for monitoring blood pressures. jpeg 6 Cannulation of right internal jugular vein. jpeg 8 Inflated balloon at the distal tip of pulmonary artery catheter. jpeg 9. Pulmonary artery catheter for continuous monitoring of cardiac output and mixed venous saturation....

References

Institute of Laboratory Animal Resources, TNRC, and the National Academy of Sciences. (1996, March) Guide for the Care and Use of Laboratory Animals. National Academy Press, Wahington, DC. 2. Gross, D.R. (ed.) (1994) Animal Models in Cardiovascular Research, 2nd Ed. Kluwer Academic, Dordrecht, The Netherlands, p. 494. 3. Ettinger, S.J. (2000) Congenital heart diseases, in Textbook of Veterinary Internal Medicine. Saunders, Philadelphia, PA, pp. 737-787. 4. Haworth, R.A., et al. (1983) Metabolic...

Conclusions

Gamma Variate Hrf

For the biomedical engineer, cardiac MRI represents an opportunity to study the function of the heart and use this insight to design better biomedical devices. Because of the increasing relevance of cardiac MRI in the clinical arena, it will become Fig. 23. Signal intensity (SI) curve for a myocardial sector in the lateral wall. Each of the data points (circles) represents the mean SI measured in the images for the user-defined myocardial sector. The images were acquired with a fast, Trweighted...

Summary

In this book, and more specifically in this chapter, numerous areas of cardiology and cardiac surgery in which the development of innovative technologies continues to mature at a rapid rate have been reviewed. These areas include (1) resuscitation systems and devices (2) implantable therapies (e.g., pacemakers, implantable cardioverter defibrillators, stents, septal occluders, valves, annular rings, fibrin patches, etc.) (3) delivery systems invasive therapies (e.g., angioplasty, ablations,...

Sr

QT dispersion in 10 patients with congestive heart failure who were treated with biventricular pacing (6 men and 4 women, aged 62 8 years, and left ventricular ejection fraction 19 7 ). There was no significant difference in QT intervals between right ventricular (RV) pacing and sinus rhythm (SR 437 36 ms vs 426 28 ms p 0.26). QT intervals were significantly shorter during biventricular (BV) pacing (407 30 ms) than during right ventricular pacing (437 36 ms p < 0.01) and during sinus...

Sources

Barash, R.G., Cullen, B.F., and Stoelting, R.K. (eds.) (2001) Clinical Anesthesia, 4th Ed. Lippincott, Williams, and Wilkins, Philadelphia, PA. Braunwald, E. (ed.) (1997) Heart Disease A Textbook of Cardiovascular Medicine, 5th Ed. Saunders, Philadelphia, PA. Faulconer, A. and Keys, T.E. (eds.) (1993) Foundations of Anesthesiology, Vols. 1 and 2. The Wood Library-Museum of Anesthesiology, Park Ridge, IL. Kaplan, J.A., Reich, D.L., and Konstadt, S.N. (eds.) (1999) Cardiac Anesthesia, 4th Ed....

Background

The first electrocardiogram (ECG) recording detailing the structure of atrioventricular conduction was made by Tawara nearly 100 years ago (1). Soon after, Mayer first observed rhythmical pulsations made in ringlike preparations of the muscular tissue of a jellyfish (Scyphomedusa cassiopeia) (2,3). In a ringlike preparation of a tortoise heart, Mines was able to initiate circulating excitation using electrical stimulation (4). Shortly thereafter, Lewis and Rothschild described the excitatory...

Conventional Methodologies

Currently, approx 10 million Americans are afflicted with cardiac arrhythmias (both ventricular and atrial) every year nonetheless, only a small percentage of patients are expected to have electrophysiological mapping procedures. Yet, cardiac electrical mapping is considered as critical for understanding the patho-physiological mechanisms that underlie arrhythmias as well as the mechanisms of their initiation and sustenance. Further, cardiac mapping is commonly used for evaluating the effect of...

Technological Innovations

Peripheral Anastomosis Device Cabg

New technologies have played crucial roles in the evolution of less-invasive cardiac surgery. Importantly, they have changed the perceptions of cardiac surgeons regarding how cardiac surgery can or should be performed. With the help of new instruments specifically designed to meet the surgeon's need, less-invasive cardiac surgical procedures once deemed impossible or impractical have now become reality, or even common practice, in some medical centers. These technological innovations have...

Yrl

Walt Lillehei in Army uniform. Fig. 2. Walt Lillehei in Army uniform. Department of Surgery at the University of Minnesota Chairs Interim Heads Department of Surgery at the University of Minnesota Chairs Interim Heads Surgery department chair interim head Arthur C. Strachauer Owen H. Wangensteen John S. Najarian Edward W. Humphrey Frank B. Cerra David L. Dunn Department chair Department chair Department chair Interim chair Interim chair Department chair

Ra

His Bundle Pacing Cxr

Cardiac output during atrioventricular sequential pacing in normal hearts. There is a 12 increase in cardiac output during His bundle pacing compared with right ventricular apical (RVA) pacing. HRA, high right atrial pacing. See ref. 5 for further discussion. Fig. 6. Cardiac output during atrioventricular sequential pacing in normal hearts. There is a 12 increase in cardiac output during His bundle pacing compared with right ventricular apical (RVA) pacing. HRA, high right atrial...

Contents

Spontaneously Occurring Animal Models of Congenital Cardiac Disease Animal Models in Myocardial Ischemia Animal Models in Heart Failure and Transplantation Animal Models for the Testing of Mechanical Devices The modern era of cardiac surgery is largely considered to have begun in the animal research laboratories. Today, animal models provide the ultimate preclinical assessment for the study of cardiovascular disease, pharmaceuticals, mechanical devices, and therapeutic procedures. This chapter...

Catheterdelivered Devices

Atherectomy Devices Design

The delivery of specialized devices that can be introduced intravascularly or intracardially has been on the rise. Such devices include stents, septal occluder devices, leads, and ablation tools (see also Chapters 6, 22, 23, and 29). An intraluminal coronary artery stent is a small, self-expanding, wire mesh tube that is placed within a coronary artery to keep the vessel patent (open). Stents are commonly deployed (1) during coronary artery bypass graft surgery to keep the grafted vessel open...

Force Production

Adenosin Myosin

In general, force production occurs as follows. First, during muscle relaxation, myosin can bind adenosine triphosphate (ATP) and hydrolyze it, but cannot use the energy released during hydrolysis to make force (Fig. 6) because of the inhibition of its binding to the thin filament by Tm and Tn. Next, after calcium binding to troponin has released the inhibition of the Tm-Tn complex on the thin filament, an energized myosin crossbridge can attach to the thin filament. This association with actin...

Future Directions

Four Coronary Artery Bypass Graft

The ultimate goal of less-invasive cardiac surgery is to avoid cardiopulmonary bypass support, sternotomy, and tho-racotomy and rather perform surgery through tiny incisions. Various of specially designed instruments have been developed to make such procedures possible, including (1) automated proximal and distal CABG anastomotic devices (2) the endo myocardium stabilizer (3) the endo suture device and (4) the endo vascular clamp. The daVinci surgical robotic system has enabled use of such...

Methods And Mechanisms

In cell transplantation, healthy cells are grafted into the diseased myocardium to elicit repair. Cells can be individual or aggregated and can be delivered either by direct injection into the myocardium or via the blood supply that feeds the myocardium. The potential utility of determined and stem cells for such a therapy have been studied. Cell transplantation studies have been primarily targeted to ischemic and segmental cardiomyopathies, as opposed to treating global, dilated...

Interventional

To date, X-ray-based fluoroscopic techniques have been the gold standard for most invasive diagnostic and therapeutic applications for the heart. With the advent of ultrafast MRI and the development of MRI-compatible catheters and guidewires, Fig. 17. (A) T2* map of an isolated beating rat heart in the short-axis view. Indicated is the epicardial myocardium (EP), the endocardial myocardium (EN), the left ventricle (LV) with a balloon inside, the collapsed right ventricle (RV), papillary muscle...

Contribution To Heart Development

The contribution of the four major embryonic regions (primary heart field, secondary heart field, cardiac neural crest, and proepicardium Fig. 1) to heart development illustrates the complexity of human heart development. Each of these regions makes a unique contribution to the heart, but they ultimately depend on each other for the creation of a fully functional organ. An understanding of the mechanisms of human heart development provides clues to the etiology of congenital heart disease....

Basic Cardiac Metabolism

The average healthy human heart weighs about 300 g or approx 0.5 of the total body mass, yet the oxygen demand of the heart accounts for 7 of the resting body oxygen consumption and consequently 5 of the cardiac output. The normal myocardial oxygen consumption MVO2 per minute is approx 8 mL O2 100 g and varies widely between normal, diseased, and exercising states. The MVO2 is primarily dependent on the coronary blood flow (CBF) and the removal of oxygen from the coronary blood as follows...

Transducer Catheters

Common clinical methods to monitor arterial and venous pressures utilize a pressure transducer system that requires a fluid-filled system. Transducer catheters such as Millar catheters (see JPEG 10 on the Companion CD) monitor pressures directly from the tip of the catheter. A sensor (see JPEG 11 on the Companion CD) placed directly at the end of the catheter allows direct and constant measurement of pressures, thus eliminating the intrinsic inaccuracies of a fluid-filled system. Transducer...

Safety

One needs to be well aware of the potential risks of any new form of therapy cell transplantation has the potential for dangerous side effects. Specifically, newly introduced cells could conceivably form cardiac or metastatic tumors, disrupt the electrical rhythm of the heart, produce inappropriate chemical signals that adversely affect normal tissue or normal physiology, or evolve pathological stiffness or fragility, leading to mechanical failure of the heart. Moreover, aberrant cellular...

Cardioplegia

In the 1950s, the consensus among cardiac surgeons was that the results of the surgical methods at that time were satisfactory (22). Yet, numerous reports described low cardiac output syndrome occurring after surgical correction of congenital anomalies (23). Unfortunately, at that time, no definitive connection was provided between the lack of proper myocardial protection during surgery and the potential for postoperative cardiac dysfunction or high mortality rates. Not until the advent of...

Guo

Compressed air seems to provide a simple and reliable way of either activating the diaphragm or compressing the sac, with a pressure more comparable to a physiologically acceptable waveform. However, this design requires a bulky driving console, compromising the patient's mobility. In other ventricular assist devices, the diaphragm is activated by a slow-torque electrical motor that is small enough to be incorporated into the implantable unit. Thus, patient mobility is significantly...

Effects Of Biventricular Pacing On Cardiac Function

Both animal and human studies have shown that, in the presence of an intrinsic intraventricular conduction delay, pacing from the left ventricle is ultimately associated with a better cardiac function (compared with sinus rhythm and right ventricular apical pacing). Several clinical trials on biventricular pacing for congestive heart failure without traditional indications for pacing, have been described and are summarized in Fig. 3. Such trials include the InSync registry (13,14), the...

Impact Of Incision Size

For years, the physical and emotional impact of a large incision size on the individual patient has been ignored by most cardiac surgeons. Historically, adequate exposure of the target tissues or organs through large skin incisions took priority over concern about incision size this mindset remained unchallenged until the early 1990s. Subsequently, with novel specially designed instruments, experience with laparoscopic surgery demonstrated that those surgical procedures traditionally performed...

Web Resources

Accessed 15 September 2004. http www.acorncv.com index2.html. Accessed 15 September 2004. http www.asme.org events nanobio . Accessed 15 September 2004. Accessed 15 September 2004. http www.bostonscientific.com . Accessed 11 November 2004. Accessed 15 September 2004. http www.ctsnet.org . Accessed 11 November 2004. 1319eb313bc7140ae08e662. Accessed 15 September 2004. Accessed 15 September 2004. http www.fda.gov . Accessed 11 November 2004. http www.guidant.com ....

1

Chemical structure of commonly administered inhalational anesthetics. science in physiology and pharmacology, and diligent monitoring of vital signs (JPEG 3). Typically, induction of general anesthesia in children by placement of an intravenous catheter for preinduction may be traumatic to the child or difficult because of noncooperation. Instead, initial mask induction with halothane, sevoflurane, or nitrous oxide is frequently utilized. After placement of American Society of...

Ribonucleic Acid

The current understanding of the important genes and molecular signaling pathways that regulate myocardial remodeling and the transition to heart failure is based largely on animal models and clinical trials. These studies have confirmed the importance of the neurohormonal systems, including the renin-angiotensin-aldosterone axis, the sympathetic nervous system, and natriuretic peptides in the pathogenesis of the heart failure phenotype (2,21-26). Furthermore, a number of recent failed drug...

Electrophysiological Study And Transcatheter Ablation

Electrophysiological study can be useful in evaluating a broad spectrum of cardiac arrhythmias. It can help to (1) assess the function of the sinus and atrioventricular nodes and the His-Purkinje system (2) determine the characteristics of reentry tachycardias (3) assess the efficacy of antiarrhythmic drugs and devices (4) map the location of arrhythmogenic foci and (5) identify sites for ablation to treat many forms of tachycardia. Electrophysiological study is performed in a laboratory...

Of Cardiopulmonary Bypass

Cardiopulmonary bypass procedures have become commonplace in cardiac surgical suites however, capabilities to perform the same clinical procedure safely without its use would be desirable, for such bypass procedures are not performed without risks. More specifically, cardiopulmonary bypass has been associated with a complex systemic inflammatory reaction in the host patient. The hallmarks of this reaction are typically increased microvascular permeability in multiple organs, resulting in an...

Myocardial Ischemia

The basic definition of myocardial ischemia is a greater myocardial tissue oxygen demand than oxygen supply. During short-term ischemic episodes, the heart's defense mechanism seeks to remedy this imbalance by downregulating myocardial contractile function and, concomitantly, increasing the rate of glycolysis (anaerobic energy production). Consequently, sar-colemmal glucose transport increases, and intracellular acido-sis resulting from a buildup of the glycolytic breakdown products causes...

Implantable Therapies

Advances in microtechnologies have now made it possible to create implantable therapies that can be lifesaving, such as implantable defibrillators, which have detected and treated thousands of episodes of sudden cardiac fibrillation. As mentioned, the potential for large numbers of such devices will likely increase at an exponential rate and will be directed specifically to all types of cardiac complications. 3.1. Left Atrial Appendage Atrial Fibrillation Therapy There are growing numbers of...

Of Biventricular Pacemaker

The key procedure for implementation of biventricular pacing is placement of the left ventricular lead. Clinical studies on multisite ventricular pacing in humans have mainly consisted of biventricular pacing modalities with transvenous left ventricular pacing via a coronary venous lead or, less commonly, a left ventricular epicardial lead through thoracotomy. It is usually necessary to target specific sites (posterolateral or lateral walls of the left ventricle) to maximize hemodynamic...

E

Postdoc Cardiac Ion Channels

Where R is the gas constant, T is the temperature (K), z is the valence of the ion (charge and magnitude), and F is the Faraday constant. In Table 1, the concentrations of the ions (inside and outside) that play a role in the resting membrane potential of cardiac muscle cells are shown with their respective calculated equilibrium potentials. The measured membrane potential of a cardiac muscle cell is approx -90 mV, suggesting that it is primarily determined by either the chloride or potassium...

Nno

Delivery system for an asymmetric device. (A) Photograph of the slot in the delivery catheter, flat at the upper margin this matches a flattened area at the upper surface of the microscrew. The microscrew will only fit into the slot in the correct orientation. (B) The asymmetric Perimembranous Ventricular Septal Occluder is attached to the curved delivery catheter. The longer rim of the left ventricular disk is oriented along the lesser curvature of the delivery catheter. Fig. 6. Angled...

Anterior Mitral Leaflet

Endocarditis and Performance Tracking All patients with prosthetic valves also need appropriate antibiotics for prophylaxis against infective endocarditis. This discussion is beyond the scope of this chapter, but refer to guidelines published by a joint committee from the American Heart Association and American College of Cardiology for the applicable protocols. A registry has been established to track the long-term performance of all clinically approved...

Arteriosus And Muscular Ventricular Septal Defect

Patent ductus arteriosus and muscular ventricular septal defects are similar communications to secundum atrial defects in that they are surrounded by normal vessel or muscular ventricular septum. More recent concentric devices, modified from the design of the Amplatzer Septal Occluder device, have now provided the clinical opportunity for transcatheter closure in patients with such defects. Patent ductus arteriosus is a failure of closure of a vascular channel present before birth it normally...

For Congestive Heart Failure

Miller, md Physiological Pacing and Resynchronization Therapy Effects of Biventricular Pacing on Cardiac Function Effects of Biventricular Pacing on Ventricular Arrhythmias Effects of Biventricular Pacing on Mechanical Remodeling Optimal Pacing Configuration Effects of Biventricular Pacing on Autonomic Nervous Activity Effects of Biventricular Pacing on Cardiac Energetics Implantation of Biventricular Pacemaker Prediction of Efficacy of Biventricular Pacing

Regulation

General and regional anesthesia are often associated with disregulation of body temperature and thus decreases in core body temperature. Most of the body heat lost during anesthesia is via convection and radiation, with some losses caused by conduction and evaporation. Principally, anesthetics cause the core body heat to redistribute to the periphery, resulting in a drop in core body temperature (58). Under anesthesia, patients become poikilotherms (have minimal ability to thermoregu-late)....

Sk Humana Press

2005 Humana Press Inc. 999 Riverview Drive, Suite 208 Totowa, New Jersey 07512 For additional copies, pricing for bulk purchases, and or information about other Humana titles, contact Humana at the above address or at any of the following numbers Tel 973-256-1699 Fax 973-256-8341 E-mail humana humanapr.com or visit our website at http humanapr.com All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic,...

The Ecg Waveform

When an ECG is recorded, a reading of voltage vs time is produced, which is normally displayed as millivolts (mV) and seconds. A typical lead II ECG waveform is shown in Fig. 2. For this recording, the negative electrode was placed on the right wrist, and the positive electrode was placed on the left ankle, giving the standard lead II ECG (explained in Section 3.1.). It shows a series of peaks and waves that corresponds to ventricular or atrial depolarization and repolarization, with each...

Pulmonary Artery Pressure Monitoring

The pulmonary artery catheter was first introduced into clinical practice by Swan and Ganz (7). Since its introduction, the pulmonary artery catheter is often used in the management of critically ill patients and in those undergoing major cardiac surgery (Table 5). Yet, the effectiveness of pulmonary artery catheter monitors and their effect on patient morbidity and mortality continues to be debated and researched (8). Current modifications also allow for continuous monitoring of pulmonary...

Procedural Improvement

With pressures on the health care system to continually reduce treatment costs and document the outcome benefits of a given therapy, much effort will continue to be placed on procedural improvements for cardiac care. The ability to image internal and external features of the heart continues to improve at a rapid rate and, as indicated in Chapters 18 and 19 on echocardiography and magnetic resonance imaging, respectively, the sophistication of such systems can be quite extreme. Yet, as the cost...

Eta

Vasodilation vasoconstriction (ETB2) cAMP inhibition PLC InsP3 calcium increase Central cardiovascular regulation (OP1, 3) cardioprotection (OP1) IK conductance activation reduction in neuronal ICa AC inhibition PKC and KATP channel activation (cardioprotection) AC, adenyl cyclase ATI, AT2, angiotensin receptor 1, 2 ETA, endothelin A ETB, endothelin B Gi, inhibitory G protein Gs, stimulatory G protein Gq 11, Go, G15, other G proteins ICa, voltage-dependent calcium channel (current) IK, voltage...

Jpeg 10 Jpeg

Monitor display of electrocardiogram, blood pressures, and SvO2 Cannulation of a peripheral artery. Cannulation of a peripheral artery. Pressure transducer for monitoring blood pressures. Central venous access kit. Cannulation of right internal jugular vein. Pulmonary artery catheter. Inflated balloon at the distal tip of pulmonary artery catheter. Pulmonary artery catheter for continuous monitoring of cardiac output and mixed venous saturation. Millar catheter. Sensors on a Millar catheter....

Medical Alley

Spurred by the flurry from Minnesota inventors of innovations such as the pacemaker, bubble oxygenator, and artificial heart valve, Medical Alley was founded in 1984 as a nonprofit trade association to support the region's growing health care industry. Medical Alley was considered to denote the rich geographic area of health care-related organizations that extended from Duluth through Minneapolis St. Paul and further south to Rochester (see www.medicalalley.org). More recently, Medical Alley...

Telemedicine

Satellite Telemedicine

Telecommunication systems and devices, including the utilization of the Internet, have experienced unpredicted growth in the last decade. This explosion in technology has the potential to revolutionize the care of all types of cardiac patients. Ambulatory heart monitors collect ECGs during daily patient activity. Today, a Holter monitor typically collects up to 48 h of continuous ECG data. The patient wears the monitor and notes

New Ischemic Syndromes

In the past, it was generally believed that extended periods of myocardial ischemia led to irreversible damage of the myocardial or infarcted (necrotic) tissue. However, more recently, between the clinical conditions of transient ischemia (angina pectoris) and myocardial infarction, five additional ischemic syndromes have been described (Figs. 2 and 3) (2,3). The stunned myocardium is characterized by postischemic impairment of myocardial function, but it is considered acute and completely...

And Outflow Tract And Atrial And Ventricular Septation

Once the chambers are in their correct positions after looping, extensive remodeling of the primitive vasculature and septation of the heart can occur. The cardiac neural crest is an extracardiac (from outside the primary or secondary heart fields) population of cells that arises from the neural tube in the region of the first three somites up to the midotic placode level (rhombomeres 6-8) (Fig. 5). Cardiac neural crest cells leave the neural tube during weeks 3-4 of human development and...

Isolated Pericardial Hemodynamic Effects And Transplantation

Heart Failure Hemodynamics

Previous experiments have suggested that, in a normal intact heart at normal levels of right ventricular diastolic filling, the pericardium does not exert constraining effects on ventricular function (3,8). However, with increasing levels of right ventricular preload pressure, pericardial constraint increases, significantly influencing right ventricular function (17). By restricting atrial filling, the pericardium causes reductions in atrial systolic contributions to ventricular filling (18),...

Pacing On Ventricular Arrhythmias

Defibrillator Implant Risks

Theoretically, biventricular pacing may alter the substrates responsible for ventricular arrhythmias and, on occasion, may possibly be associated with an increased risk for ventricular arrhythmias. However, currently available data indicate that biventricular pacing reduces the likelihood of ventricular tachyarrhythmias. In addition, there is evidence that biventricular pacing actually inhibits ventricular reentry. Several studies obtained from a small number of patients demonstrated that...

Qrs

Ecg Wave With Cvp Wave Forms

Central venous pressure wave. The central venous pressure waveform consists of a, c, v waves and x and y descents. The a wave is associated with atrial contraction. The c wave occurs as the tricuspid valve bulges up toward the right atrium during early ventricular systole. The v wave is associated with passive filling of the right atrium with closed valve. The x descent corresponds to the tricuspid valve being pulled down toward the right ventricle during late systole. The y descent...

Cardiac Pressurevolume Curves

Ventricular function can be analyzed and graphically displayed with a pressure-volume diagram. Both systolic and di-astolic pressure-volume relationships during a single cardiac cycle are displayed in Fig. 2. Pressure-volume assessment of myocardial function on intact myocardium involves multiple factors, such as preload, afterload, heart rate, and contractility. The area inside the pressure-volume loop is an estimate of the myocardial energy (work pressure x volume) utilized for each stroke...

Proepicardium And Coronary Artery Development

The last major contributor to vertebrate heart development discussed in this chapter is the proepicardium. Prior to heart looping, the primary heart tube consists of endocardium, cardiac jelly, and myocardium. It is not until the start of heart looping that the epicardium surrounds the myocardium, forming the fourth layer of the primary heart tube (Fig. 3) (22). This population of cells will eventually give rise to the coronary vasculature. A neural crest origin of the coronary vessels was...

Future

The future of ventricular assist devices is promising. Currently, we seem to be dealing with early prototypes. Many minor and major advances will take place in the field when we finally have a long-term device that can replace circulatory function. Nevertheless, any device should possess most of the following characteristics 1. It must be totally implantable to lower the risk of infection significantly and to improve the quality of life for patients. Fig. 5. One of the author's former patients...

Heart Tones

Physiology and Normal Heart Sounds Heart tones are caused primarily by vibrations created by pressure differentials during closure of the heart valves. Normal opening of the heart valves is a relatively slow process and makes no audible sounds. The heart tones are relatively brief and characterized by varying intensity (loudness), frequency (pitch), and quality (timbre). To understand heart tones better, it is necessary to review briefly the physiology of cardiac events. The electric...

Crosscirculation

Extracorporeal circulation by controlled cross-circulation was introduced clinically on March 26, 1954 (Fig. 5). The use of cross-circulation for intracardiac operations was an immense departure from established surgical practice at the time and was the major breakthrough that motivated innovations in the area of open heart surgery (3). The thought of taking a normal healthy human being into the operating room to provide donor circula tion was considered unacceptable and even immoral by some...

Guanylatecyclaselinked Receptors

Soluble Guanylyl Cyclase (Receptor for Nitric Oxide) Although structurally different, the general principles of receptor signaling as discussed for p-AR apply also for nitric oxide guanylyl cyclase (GC) signaling. Specifically, the agonist (nitric oxide) is a universal signaling molecule present in all tissues, and its role is important not only in normal physiology, but also in disease. Physiologically, nitric oxide is produced by several isoforms of the enzyme nitric oxide synthase...

Cardiac Maturation

Although the embryonic heart is fully formed and functional by the 11th week of pregnancy, the fetal and neonatal heart continue to grow and mature rapidly, with many clinically relevant changes taking place after birth. During fetal development, or from the time after the embryo is completely formed in the first trimester of pregnancy until birth, the heart grows primarily by the process of cell division (28-31). Within a few weeks after birth, the predominant mechanism of cardiac growth is...

Hypothalamic Control

Afferent Fibers Parasympathetic Nervous

The autonomic control of the heart is highly modulated by activity within the portion of the brain known as the hypothalamus. Afferent fibers from the brain stem (medulla oblongata) and spinal cord convey information via the autonomic afferent system to the hypothalamic nuclei within the central nervous system (10), whereas impulses that leave the hypothalamus travel along efferent fibers to the various sympathetic and para-sympathetic ganglia as noted above. Most parasympathetic response...

Some Basic Interpretation Of The Ecg Trace

Cross Section The The Heart

The ECG waveform and mean electrical axis are quite useful in the clinical setting. The ECG is considered one of the most important monitors of a patient's cardiovascular status and is commonly used for measurements as basic as the heart rate. Most ECG monitoring devices used today include automated systems that detect changes in durations between subsequent QRS complexes (i.e., the duration of one cycle). Simply, determination of the PR intervals provides information regarding whether a...

Physical Principles Of Echocardiography

Echocardiography uses the properties of sound waves to differentiate tissues of varied density in the human body. Sound travels in mechanical waves with a speed dependent on the density and elastic properties of the medium in which they are traveling (2). This property of tissue is termed its acoustic density. Ultrasound waves, which are used in medical applications, have frequencies that are higher than those audible to the human ear. ultrasound frequencies are generally over 20,000 cycles per...

Of Anatomy And Animal Research

Anatomy is one of the oldest branches of medicine, with historical records dating back at least as far as the 3rd century bc animal research dates back equally as far. Aristotle (384-322 bc) studied comparative animal anatomy and physiology, and Erasistratus of Ceos (304-258 bc) studied live animal anatomy and physiology (1). Galen of Pergamum (129-199 ad) is probably the most notable early anatomist who used animals in research to attempt to understand the normal structure and function of the...

Protein

Dimensional Gel

Interest in proteomics-based technology and strategies was buoyed, in part, by the somewhat surprising finding that the human genome contained 30,000-40,000 open reading frames, a number much smaller than expected and similar to that of lower organisms. This suggested that the level of diversity and complexity in the human is partly caused by alternative mRNA splicing and posttranslational protein modifications, including such processes as phosphorylation and oxidation reduction. Proteomics is...

And Bioenergetics In The Normal Heart

Glucose Phosphate Heart Failure

Carbon Substrate Selection The primary carbon substrates (Fig. 4) taken up and metabolized by the myocardium are free fatty acids and glucose. The heart readily takes up and metabolizes pyruvate, lactate and ketone bodies, but the generally low blood concentrations of these substrates limit their utilization. However, under certain conditions such as exercise, which can markedly elevate the blood lactate content, or during periods when blood levels of ketone bodies are elevated,...

Abdominal Defibrillator

Epicardial Medtronic Icd Patches

Antiarrhythmic agents can also be proarrhythmic, which may lead to an increased requirement for ICD therapies. Predisposing factors to proarrhythmias are (1) electrolyte imbalances such as hypomagnesemia or hypokalemia, (2) underlying ventricular arrhythmias, (3) ischemic heart disease, and (4) poor left ventricular function. One of the most dangerous forms of proarrhythmia is considered torsade de pointes or twisting of the points. Specifically, torsade is a rapid form of polymorphic...

Postventricular Atrial Blanking

Loss Capture Pacemaker

Schematic of a lithium iodide battery. This is the most common chemistry used in modern pacemakers. Fig. 9. Schematic of a lithium iodide battery. This is the most common chemistry used in modern pacemakers. Fig. 10. Cutaway view of an implantable pulse generator (IPG, or pacemaker). 4.4. North American Society of Pacing and Electrophysiology and British Pacing and Electrophysiology Group Codes To describe the function of a pacing system in a standardized manner, the North American...

Failure And Transplantation

Alexis Carrel reported the first heterotopic transplantation (Table 4) of a canine heart connected to the neck vessels of another dog in 1905 the animal succumbed to massive clotting and survived for only 2 hours. Over the next 55 yr, Drs. Richard R. Lower and Norman E. Shumway ultimately perfected an orthotopic transplantation in the canine. In contrast to Carrel's original work, transplants in Shumway's laboratory research were placed orthotopically, and animals survived for up to 21 days...

Lead Placement In The Clinical Setting

Monitorizaci Derivadas

In a clinical setting, not all 12 leads are displayed at the same time, and most often, not all leads are measured simultaneously. A common setup used is a five-wire system consisting of the two arm leads, which are actually placed on the shoulder areas, two leg leads placed where the legs join the torso, and one chest lead. This arrangement allows display of any of the limb leads (I, II, III, aVR, aVL, and aVF) and one of the precordial leads, depending on where the chest electrode is placed....

Output To Organs

Lymphatic Circulation Sequence

Relaxed skeletal muscles Contracted skeletal muscles Fig. 3. Contractions of the skeletal muscles aid in returning blood to the heart this is termed the skeletal muscle pump. While standing at rest, the relaxed vein acts as a reservoir for blood contractions of limb muscles not only decrease this reservoir size (venous diameter), but also actively force the return of more blood to the heart. Note that the resulting increase in blood flow caused by the contractions is only toward the heart...

Introduction To Implantable Pacing And Defibrillation Systems

Defibrillation Heart Failure

Implantable pacing and defibrillation systems require multiple components, as well as external instruments, for proper function and programming. The implantable portion of the system is composed of the implantable pulse generator (IPG, or pacemaker) or an implantable cardioverter-defibrillator (ICD, or defibrillator) and the pacing and or defibrillation leads. The IPG and ICD are most commonly implanted in a subcutaneous location in the left pectoral region. Typically, depending on the...

Training Systems

Medtronic Loop Recorder

As technologies have become more and more advanced, so has the need to teach students, residents, and physicians how to use them. New products to enhance medical training are rapidly entering the marketplace. The most impressive new systems incorporate computerized mannequins, complex graphics, and sophisticated operator controls in state-of-the-art patient simulators. Students, residents, or physicians learn both medical concepts and manual procedures on life-size, interactive equipment that...

Pathway Hemothorax

Heart Failure Electrocardiogram

Measurements in the His bundle electrogram for evaluation of atrioventricular conduction. AH interval, measured from the earliest reproducible rapid deflection of the atrial electrogram in the His recording to the onset of the His deflection, represents conduction time from the low right atrium at the interatrial septum through the atrioventricular node to the His bundle (atrioventricular node function). The HV interval, measured from the beginning of the His deflection to the earliest...

Optimal Pacing Configuration

Left Ventricular Conduction Delay

Right ventricular pacing by itself is considered suboptimal today, although several studies have shown that pacing from the high right ventricular septum or right ventricular outflow tract may be associated with better cardiac function compared to pacing within the right ventricular apex (8,35,36). However, this observation was not confirmed by other investigators (37,38). It appears that pacing in a position that results in the greatest reduction in QRS durations may be associated with the...

Excitation-contraction Coupling Of Cardiac Cells

Relative Refractory Period

Eion, the equilibrium potential calculated from the Nernst equation. Eion, the equilibrium potential calculated from the Nernst equation. Action Potential Duration Atrium 150 ms Fig. 14. Ionic conductance changes during the ventricular cardiac action potential. See text for details. Cardiac action potentials occur because of transient changes in the cellular permeability to sodium, calcium, and potassium. A brief increase in sodium permeability depolarizes the cell and drives the membrane...

Cmc Closed Mitral Commissurotomy

Tricuspid Valve Leaflet Failure

Ventricular septal defects with aortic cusp prolapse left ventricular dilation to accommodate a larger volume without changing filling pressures and by ventricular hypertrophy, allowing ejection of a larger total stroke volume (31). The majority of such patients remain asymptomatic for prolonged periods of compensation, during which time they maintain forward stroke volume within the normal ranges. Once the left ventricle can no longer compensate, patients may present with symptoms of dyspnea...

The Cardiac Skeleton

Passing transversely through the base of the heart is a fibrous framework or skeleton made of dense connective tissue, not bone as the name might suggest. The purpose of this tough, immobile scaffold is to (1) provide an attachment for the atrial and ventricular myocardium, (2) anchor the four valves of the heart, and (3) electrically insulate the myocardium of the ventricles from the atria. The supporting framework of the cardiac skeleton (Figs. 15 and 18) provides immobile support for the...

What If Heart Beat Goes Fast Frequently And Qt And Pr Intervals Are Not Normal

What Ventricular Fibrillation

The normal heartbeat is initiated by specialized cardiac cells (so-called pacemaker cells) located in the right atrium adjacent to its junction with the superior vena cava. These cells make up a specialized, albeit somewhat diffuse, region of the right atrium called the sinus node. The rate and regularity of activity in the sinus node (the cardiac pacemaker) is determined by both the intrinsic firing rate (automaticity) of the cells within the node and the influence of extrinsic factors on...

P3 Heart Disease

Primary G protein Tissue distribution Primary effector in heart tissue Vessels, heart, lung, kidney Adenylyl cyclase, L-type calcium channel cAMP PKA, MAPK cAMP, cyclic adenosine 3',5'-monophosphate Gi, inhibitory G protein Gs, stimulatory G protein MAPK, mitogen-activated protein kinase PKA, protein kinase A. been made to classify them according to different subtypes. For example, common a-subunits include (1) as (stimulatory), which activates adenyl cyclase (AC) (2) (inhibitory), which...

Uws

Donald Ross Bunker Drawings

Heart lung machine developed at the University of Minnesota Fig. 4. Drs. Richard Varco and F. John Lewis standing with a cooling by Dr. C. Walton Lillehei and Dr. Richard DeWall. Photo courtesy of device used during open heart surgery. Photo courtesy of the Lillehei Anticoagulation After Prosthetic Heart Valves First 3 months postimplantation First 3 months postimplantation Source From ref. 7. INR, international normalized ratio. Tissue Valve Graft Options Classification of...

Ekg Hegzaaxial System

Lead Sagittal Plane The Heart

The amplitudes of the lead I and II R waves are plotted along the corresponding leg of Einthoven's triangle starting at the midpoint and drawn with a length equal to the height of the R wave (units used to measure the amplitude can be arbitrary because the direction, not the magnitude, of the axis is important). The direction of the plot is toward the positive end of the lead if the R wave has a positive deflection and negative if it has a negative deflection. Perpendiculars from each...

And Techniques Of Cardiac

Transverse Plane Images Mri

Felix Bloch and Edward Purcell discovered independently, in 1946 (1,2), that nuclei with a magnetic dipole moment gave rise to a resonance phenomenon when immersed in a magnetic field and subjected to a pulsed or continuous radiofrequency excitation. MR is based on the interaction of nuclear magnetic moments with externally applied magnetic fields, both static fields and time-varying fields. For the sake of simplicity, we can think of atomic nuclei having an intrinsic angular momentum called...

Future Research

Although much is known, a great deal of supposition and controversy remain associated with the understanding of the cardiac conduction system. Specifically, characterization of the anatomy and electrophysiology of the atrioventricular nodal Comparison of Swine to Human Electrophysiology Comparison of Swine to Human Electrophysiology

Animal Models In Valve Disease

Cory Swingen

The significant morbidity and mortality associated with heart valve disease has produced a highly lucrative and competitive market for manufactured prosthetic valves. Efforts to develop the ideal replacement heart valve have focused on producing a product that functions like the native valve Table 2 . The dynamics of blood flow through a tube with its specific viscosity is such that the flow is greatest in the center of the tube. Thus, any structure in the center of the valve i.e., mechanical...

I

Late Stages Heart Failure

Little or No Recovery of Contractile Function Fig. 2. Consequences of myocardial ischemia. The stunned myocardium usually results from a transient coronary occlusion followed by prompt reperfusion however, it may also occur following prolonged ischemia in the preconditioned heart. Preconditioning may lessen the infarct area following a sustained coronary occlusion however, the relationship between preconditioning and the maimed myocardium is unknown. Modified from ref. 15. 1995, with permission...

Physiologic Effects Of Acupuncture

Acupuncture involves stimulation of specific anatomical locations on the skin to alter energy flow patterns throughout the body. The skin can be stimulated by manual or electrical stimulation or the more typical placement of small metallic needles. Acupuncture has been used in China for thousands of years there has been a surge of interest in these nontraditional methodologies in the United States. Acupuncture has been utilized for treatment and prevention of multiple health conditions, such as...

Anesthesia Induction Sequence

A typical general anesthesia induction sequence for an adult is as follows after establishing intravenous access and placement of standard American Society of Anesthesiologists 1 monitors, a patient is preoxygenated with 100 oxygen. An induction dose of intravenous medications such as propofol, an opioid, and a muscle relaxant are administered see JPEG 1, on the Companion CD and description at end of chapter . After the patient is rendered unconscious and anesthetized, direct laryngoscopy is...

Myocardial Blood Flow

Subendocardial Plexus

Blood containing carbon substrate and oxygen is delivered to the heart by two main coronary arteries that originate from the proximal aorta and course over the surface of the heart epi-cardium . These arteries arborize into progressively smaller branches that turn inward to penetrate the epicardium and supply blood to the myocardium Fig. 2 . In the left ventricle, the heart muscle is typically subdivided into transmural layers these are termed the subepicardium outer layer , the midmyo-cardium,...

Inhalational Anesthetics

Commonly used inhalational anesthetics include nitrous oxide, isoflurane, desflurane, halothane, and sevoflurane Fig. 1 . Each of these inhalational anesthetics has a specific minimum alveolar concentration MAC at which general anesthesia is considered induced Table 2 . MAC is defined as the minimum alveolar concentration of an inhaled anesthetic required to prevent movement in 50 of patients in response to a surgical incision. It is important to note that infants have a higher MAC than adults,...

Cells

Harvesting Embryonic Stem Cells

A decision of primary importance in cell transplantation is the selection of cell type. Presented in this section is a survey of the major cell types investigated by various laboratories to date. 3.1.1. Fetal and Neonatal Heart Muscle Cells The transplantation of fetal or neonatal cardiomyocytes into myocardial scar tissue is intended for directly restoring contractile function to tissue deficient in its own cardiomyocytes. The motivating hypothesis is that healthy, young cardiomyocytes can...

Surface Anatomy

Sternal Angle Surface Anatomy

Landmarks of the Thoracic Wall There are several defined vertical lines that demark regions of the anterior and posterior thoracic wall Fig. 23 . These lines are used to describe the location of surface landmarks and the locations of injuries or lesions on or within the thorax. The anterior median line runs vertically in the midline. It is also referred to as the midsternal line. The midclavicular line bisects the clavicle at its midpoint and typically runs through or close to the nipple....

Mechanical Effects Of The Pericardium

The degree to which the pericardium alters wall movement varies depending on the ratio of cardiac to pericardial size, loading conditions, and the degree of active and passive filling. Closure of the pericardial sac following open heart surgery has been proposed to 1 avoid possible postoperative complications, 2 reduce the frequency of ventricular hypertrophy, and 3 facilitate future potential reoperations by reducing fibrosis 1 . Differences in ventricular performance dependent on the presence...

Resuscitation Systems And Devices

Handhelp Lifepack Lead

Even before the cardiac patient enters the emergency or operating room, there are many new technologies being developed to aid in the resuscitation of an individual who has suffered from cardiovascular failure. Such devices range from improvements of existing tools e.g., the automated application of cardiopulmonary resuscitation or CPR to novel mechanisms that accomplish improved outcomes e.g., an impedance threshold valve . Furthermore, automated external defibrillators have become commonplace...

Cardiac Defibrillation

Implantable Cardioverter Defibrillator

Today, sudden cardiac arrest death is one of the most common causes of mortality in developed countries 3 million people experience sudden cardiac arrest worldwide, and the annual incidence in the United States is 300,000. Sudden cardiac arrest claims more lives in the United States each year than the combination of deaths from acquired immunodeficiency syndrome AIDS , breast cancer, lung cancer, and stroke 31 . Several studies have identified the primary risk factors for sudden cardiac arrest,...

Mri Pulse Sequence Diagrams

Mri Haste Pulse Sequence Diagram

Mx i My p x, y exp -ikxx p cos kxx i sin kxx Fig. 5. Waveforms that are applied along the radiofrequency R.F. and one gradient channel during a slice-selective radiofrequency excitation. The gradient channels are typically given logical names, such as slice-select and readout. The direction for the slice selection gradient can be arbitrary and is achieved by using three equivalent gradient coil sets for gradients in the x, y, and z directions and applying a combination of waveforms on all...

Animal Models In Myocardial Ischemia

Myocardial Ischemia Pictures

Despite tremendous advances in treatment options, atherosclerotic coronary vascular disease remains the leading cause of death worldwide. As a result, this disease continues to be an active area of cardiovascular research. Originally defined by the Greeks as a lack of blood flow, the modern definition of ischemia emphasizes both the imbalance between oxygen supply and demand and the inadequate removal of waste products. Impaired oxygen delivery results in a reduction in oxidative...

Perfusion Analysis

Artifacts Myocardial Perfusion Imagin

Myocardial perfusion is a measure of blood flow e.g., mL min per unit mass of myocardial tissue. Myocardial perfusion should ideally match the demand for oxygen in the myocardium. Perfusion is commonly assessed at both rest and with induced stress to evaluate the capacity of the coronary circulation to increase blood flow above its baseline level and thus match increases in oxygen demand. A ratio of the perfusion parameters, measured at stress and divided by the value for rest, will give a...