Anatomy of the heart

The heart, enveloped in the fibrous pericardium, occupies the middle mediastinum. This article describes the essentials of external and internal cardiac anatomy, and highlights those aspects of cardiac functional anatomy that are of particular relevance to clinical cardiac examination.     

Clinically applied anatomy of the pelvis

The bony pelvis is an irregular but complete bony ring made up of the right and left hip bones anterolaterally and the sacrococcygeal part of the vertebral column posteriorly. The two hip bones are firmly united anteriorly at the pubic symphysis, and together constitute the pelvic girdle. The pelvic girdle articulates with the femoral heads and thereby connects the vertebral column (axial skeleton) to the two femora (appendicular skeleton). The main functions of the pelvic girdle are to transmit weight from the upper body to the lower limbs during locomotion and while standing, and to support the weight of the upper body when seated or stationary. Another important function of the bony pelvis is to provide attachment for the powerful muscles (e.g. gluteal muscles) that act on the lower limb and those muscles that support the abdominal wall. The bony pelvis also provides ample protection to the many delicate viscera, vessels and nerves that lie within the pelvic cavity. Successful orthopaedic management of disruptions of the bony pelvis and management of associated injuries to intrapelvic viscera require a sound appreciation of the anatomy of the pelvic ring and pelvic cavity.     

Effect of Surgical Reconstruction on Flow Profiles in the Aorta Using Magnetic Resonance Blood Tagging

Background. The aorta that has undergone an aorta-pulmonary artery anastomosis may not exhibit the same velocity profile as the nonreconstructed aorta, whose velocity profile is thought to be uniform across the vessel diameter (plug flow). This may have an impact on fluid dynamics and will alter Doppler flow calculations. Our objective was to determine the impact of surgical reconstruction on the velocity and flow profiles of the reconstructed ascending and descending aorta.

Methods. Using a magnetic resonance imaging tagging technique that labels flowing blood (bolus tagging), we studied 22 patients (mean age, 8.6 ± 4.7 years) who had had a Fontan procedure. A cine sequence labeled the blood and acquired the image after 20 ms in the middle of the ascending aorta and behind the left atrium in the descending aorta. The repetition time was 50 ms.

Results. The reconstructed ascending aorta displayed a velocity profile skewed anteriorly, whereas in the nonreconstructed aorta, the velocity profile was flat. Reconstructed aortas also displayed flows that were higher anteriorly, took a longer time to reach maximum velocity, and were less like “plug” flow than the nonreconstructed aorta. The descending aorta, regardless of whether aortic reconstruction was present, displayed velocity profiles (at various phases of systole) skewed posteriorly.

Conclusions. The reconstructed aorta displays disturbed flow, and the velocities across the ascending aortic diameter are more varied than those in aortas without reconstruction and are skewed anteriorly. The descending aortic velocity profile in children is skewed posteriorly, regardless of whether aortic reconstruction is present. This information may help design and build a “better” aortic reconstruction.     

Propulsion of blood through the right heart circulatory system

Venous return, the right heart function and the pulmonary circulation is an integrated functional unit. The right ventricle is particularly load sensitive, and will be influenced directly by the venous and pulmonary physiology. In this paper we present important physiological principles that govern the diagnosis and treatment of dysfunctions affecting the return of blood to the heart and the transfer of the cardiac output from the right to the left side. We do evaluate both basic science and the clinical literature pointing to practical aspects of physiological knowledge.     

The pericardium exerts constraint on the right ventricle during cardiac surgery

The right ventricle may be particularly susceptible to the effects of pericardial constraint. This study examined the effects of pericardiotomy on right ventricular function. Twenty-four anesthetized patients with coronary artery disease, but without evidence of pericardial pathology, were studied. Anesthesia consisted of fentanyl (100 micrograms.kg-1), diazepam, pancuronium, and 100% oxygen. The American Edwards REF-1 Cardiac Output Computer, rapid-response thermistor pulmonary arterial catheter, and a radial arterial catheter were used to measure hemodynamic variables. Baseline measurements were obtained with the sternum fully retracted. The measurements were then repeated following pericardiotomy by a midline incision. There were significant (P less than 0.05) changes in systolic arterial pressure (+4.5%), mean arterial pressure (+3.7%), systolic pulmonary arterial pressure (+11.8%), cardiac output (+9.1%), stroke volume (+6.9%), right ventricular end-diastolic volume (+7.6%), and right atrial pressure (-8.6%). In the current study, pericardiotomy augmented right ventricular diastolic filling and stroke volume, while the right atrial pressure decreased. These results support the concept of pericardial constraint.     

Dominance of free wall radial motion in global right ventricular function of heart transplant recipients

Assessment of right ventricular (RV) function using conventional echocardiography might be inadequate as the radial motion of the RV free wall is often neglected. Our aim was to quantify the longitudinal and the radial components of RV function using three‐dimensional (3D) echocardiography in heart transplant (HTX) recipients. Fifty‐one HTX patients in stable cardiovascular condition without history of relevant rejection episode or chronic allograft vasculopathy and 30 healthy volunteers were enrolled. RV end‐diastolic (EDV) volume and total ejection fraction (TEF) were measured by 3D echocardiography. Furthermore, we quantified longitudinal (LEF) and radial ejection fraction (REF) by decomposing the motion of the RV using the ReVISION method. RV EDV did not differ between groups (HTX vs control; 96 ± 27 vs 97 ± 2 mL). In HTX patients, TEF was lower, however, tricuspid annular plane systolic excursion (TAPSE) decreased to a greater extent (TEF: 47 ± 7 vs 54 ± 4% [?13%], TAPSE: 11 ± 5 vs 21 ± 4 mm [?48%], P < .0001). In HTX patients, REF/TEF ratio was significantly higher compared to LEF/TEF (REF/TEF vs LEF/TEF: 0.58 ± 0.10 vs 0.27 ± 0.08, P < .0001), while in controls the REF/TEF and LEF/TEF ratio was similar (0.45 ± 0.07 vs 0.47 ± 0.07). Current results confirm the superiority of radial motion in determining RV function in HTX patients. Parameters incorporating the radial motion are recommended to assess RV function in HTX recipients.     

Applied anatomy of the superior vena cava-the carina as a landmark to guide central venous catheter placement

Background. Cardiac tamponade is a serious complication of centralvenous catheter (CVC) insertion. Current guidelines stronglyadvise that the CVC tip should be located in the superior venacava (SVC) and outside the pericardial sac. This may be difficultto verify as the exact location of the pericardium cannot beseen on a normal chest x-ray. The carina is an alternative radiographicmarker for correct CVC placement, suggested on the basis ofstudies of embalmed cadavers. Methods. We set out to confirm this radiographic landmark in39 fresh cadavers (age 58.4 (3.4) (mean and SE) yr) and to comparethe results with those from ethanol–formalin-fixed cadavers. Results. We found that the carina was 0.8 (0.05) cm above thepericardial sac as it transverses the SVC. In no case was thecarina inferior to the pericardial reflection and our studyconfirmed the previous findings. All the measured distanceswere significantly greater in fresh cadavers. Conclusions. We confirm that the carina is a reliable, simpleanatomical landmark that can be identified in vivo for the correctplacement of CVCs outside the boundaries of the pericardialsac. Br J Anaesth 2004; 92: 75–7     

Surgical strategies for anomalous origin of the left coronary artery from the right pulmonary artery with an intramural aortic course: A report of 10 cases

Objective

Few data are available regarding the surgical strategies for an anomalous origin of the left coronary artery (LCA) from the right pulmonary artery (RPA) with an intramural aortic course. We reviewed our experience in a case series of 10 children.

Pulsating varicose veins!! The diagnosis lies in the heart

Right heart failure is associated with increased systemic venous pressure, which can be diagnosed clinically with the findings of elevated jugular venous pressure, pulsatile liver and distinctive cardiac murmurs (precordial systolic). Severe tricuspid regurgitation (TR) has occasionally been known to lead to marked pulsation of varicose veins. We report three cases that were referred to the vascular clinic of Royal Perth Hospital in which the patients involved had unilateral (right leg) varicose veins and chronic venous ulcers. On clinical examination all three patients had pulsations along the course of the varicose long saphenous vein up to the mid calf. The main differential diagnosis was arterio-venous malformation, which was excluded by compression of the sapheno-femoral junction and demonstrating absence of pulsation in the long saphenous vein. A venous duplex scan showed a grossly incompetent sapheno-femoral junction with abnormal wave forms. Two of the cases were managed conservatively with compression dressing. The option of sapheno-femoral junction ligation was reserved in one patient who had unsettling cellulitis and oedema of the lower limb in spite of compression dressing and optimal conservative management. All three patients had improvement in ulcer size at 3-month follow up with compression therapy. This article highlights that in cases of right heart failure the venous pressures can be felt as low as the mid calf level and that can be a cause of the venous ulcers. There should be a high suspicion of right heart failure in patients with late onset venous insufficiency.     

Physiopathological approach to infective endocarditis in chronic hemodialysis patients: left heart versus right heart involvement

Infectious endocarditis (IE), a complication that is both cardiac and infectious, occurs frequently and is associated with a heavy burden of morbidity and mortality in chronic hemodialysis patients (CHD). About 2–6% of chronic hemodialysis patients develop IE and the incidence is 50–60 times higher among CHD patients than in the general population. The left heart is the most frequent location of IE in CHD and the different published series report a prevalence of left valve involvement varying from 80% to 100%. Valvular and perivalvular abnormalities, alteration of the immune system, and bacteremia associated with repeated manipulation of the vascular access, particularly central venous catheters, comprise the main factors explaining the left heart IE in CHD patients. While left-sided IE develops in altered valves in a high-pressure system, right-sided IE on the contrary, generally develops in healthy valves in a low-pressure system. Right-sided IE is rare, with its incidence varying from 0% to 26% depending on the study, and the tricuspid valve is the main location. Might the massive influx of pathogenic and virulent germs via the central venous catheter to the right heart, with the tricuspid being the first contact valve, have a role in the physiopathology of IE in CHD, thus facilitating bacterial adhesion? While the physiopathology of left-sided IE entails multiple and convincing mechanisms, it is not the case for right-sided IE, for which the physiopathological mechanism is only partially understood and remains shrouded in mystery.     

The spectrum of clinical manifestation of anomalous origin of the left coronary artery and surgical management.

Intercoronary collaterals play a major role in determining whether patients with the symptoms of anomalous left coronary artery will suffer infarction early in life with resultant complications or will survive to an older age before becoming symptomatic with angina. We believe that the definitive surgical treatment should be performed at the earliest age possible to avoid further damage to myocardial muscle.     

Persistence of Mammary Artery Branches and Blood Supply to the Left Anterior Descending Artery

Background. Partial harvesting of the left internal mammary artery (LIMA) is a widespread technique used during minimally invasive coronary operations performed through a left anterior small thoracotomy. The influence of persisting LIMA branches was investigated to evaluate their effect on the blood flow of the left anterior descending artery.

Methods. Thirty patients, 15 with totally (group A) and 15 with partially (group B) harvested LIMAs, were evaluated. All the patients underwent postoperative angiography, during which a flow map of the LIMA was performed. The average peak velocity and the diastolic-to-systolic peak velocity ratio were recorded. The LIMA graft flow pattern was recorded in the proximal and distal thirds of the artery. Intramammary adenosine (12 to 14 μg) was injected and the average peak velocities before and after injection were calculated.

Results. The average peak velocity was similar in both groups in the proximal and distal thirds of the LIMA (25 ± 7 and 26 ± 5 cm/sec, respectively, in group A versus 27 ± 5 and 25 ± 5 cm/sec, respectively in group B; p = NS). The diastolic-to-systolic peak velocity ratio was similar proximally (0.78 ± 0.3 in group A versus 0.69 ± 0.3 cm/s in group B; p = NS), but not distally (1.72 ± 0.1 in group A versus 0.97 ± 0.3 in group B; p < 0.0005). The LIMA graft flow reserve was similar both proximally and distally (2.6 ± 0.6 and 2.5 ± 0.3 cm/s, respectively, in group A versus 2.6 ± 0.5 and 2.6 ± 0.3 cm/s, respectively, in group B; p = NS).

Conclusions. The persistence of LIMA branches does not influence the blood flow of the left anterior descending artery after acute adenosine-induced myocardial hyperemia. If a left anterior small thoracotomy is used in left anterior descending artery direct revascularization, complete LIMA harvesting is not mandatory and depends on the personal preference of the surgeon.     

影像学诊断先天性左冠状动脉主干闭锁

目的探讨影像学诊断先天性左冠状动脉主干闭锁(LMCAA)的可行性。方法回顾性分析6例LMCAA患者,男3例、女3例,1例成人、5例婴幼儿。6例均接受超声心动图、多排螺旋CT(MDCT)及心血管造影检查。结果 1例超声提示左冠状动脉内径偏细,起源显示欠清晰,不除外左冠状动脉异常起源于肺动脉;1例超声提示左冠状动脉近段发育细,似壁内走行、开口狭窄;另4例超声仅提示二尖瓣脱垂并大量反流,冠状动脉未探及异常。5例经MDCT明确诊断为左冠状动脉主干闭锁,1例不除外左冠状动脉主干开口重度狭窄或闭锁。6例经心血管造影检查均明确诊断为LMCAA。结论 LMCAA属罕见先天性心脏病,超声可提示该病;CT对多数患者可明确诊断;心血管造影检查是诊断LMCAA的金标准。     

左心辅助对犬缺血右心室的影响

目的　观察左心辅助对缺血右心室的影响。方法　 2 0条健康犬按不同左心辅助流量随机分为 4组 :Ⅰ组 :对照组 ;Ⅱ组 :辅助流量为 5 0ml·kg-1·min-1;Ⅲ组 :辅助流量为 70ml·kg-1·min-1;Ⅳ组 :辅助流量为 90ml·kg-1·min-1。结扎右冠状动脉 8min ,应用气动左心辅助装置行左心房至升主动脉辅助 3h。观察右心血流动力学及右心室心肌ATP、心肌超微结构的变化。结果　与对照组相比 ,阻断右冠状动脉近端 (RCA)前 ,Ⅱ、Ⅲ、Ⅳ组各项动力学指标差异均无显著性 (P >0 .0 5 ) ,阻断RCA 8min ,Ⅱ、Ⅲ组右心室最大压力上升速率 (Rvdp/dtmax)减小 (P <0 .0 5 ) ,全肺阻力(TPR)降低 (P <0 .0 5 ) ,右心排血量 (RCI)及ATP含量差异无显著性 (P >0 .0 5 ) ,心肌超微结构的变化大致相似。Ⅳ组Rvdp/dtmax减小 ,TPR升高 ,RCI减少 ,ATP含量降低 (P值均 <0 .0 1) ,心肌超微结构病变加重。结论　高流量左心辅助导致缺血右心室的功能恶化衰竭。