By T. Sibur-Narad. University of South Carolina, Beaufort.
The of thin cartilage usually 3–4×15–20 mm in size placed just upper lateral cartilages and lower lateral cartilages (tip) are deep to the cephalic edge of the existing lateral crus will pro- often crooked too buy discount toprol xl 50mg on line. If task of unraveling the nose and its part begins with an open the problem is small purchase 100mg toprol xl free shipping, a simpler procedure is the use of the alar approach 50 mg toprol xl overnight delivery. All the maneuvers to be described can be done with rim contour graft as described by Rohrich et al. For a closed approach but are exceptionally difﬁcult for obvious minor problems associated with concave rims, suture tech- reasons. The mucoperichondrium is elevated bilaterally mattress sutures on the convex side of a concave cartilage, the from the entire cartilaginous septum and parts of the bony eth- rim can often become straight and stiff. The vomerine ridge is spared from this dissection if at all possible because it is tedious and perforation is likely. If so, it is only necessary to Thin-skinned noses have the advantage that the surgeon free the mucoperichondrium from the existing L-shaped strut. One many the end result may be a severely weakened and collaps- of the best padding is fascia. If the vertical component is curved, a cartilage deep temporalis fascia can be enormously helpful in cor- graft may be applied as a batten. Alternatively horizontal mat- recting the thin-skinned secondary rhinoplasty patient. The horizontal Figures 29, 30, and 31 demonstrate a patient whose thin component can be reinforced with horizontal mattress sutures skin adversely affected her result. The upper lateral cartilages and fascia graft placed over the entire tip framework softened septum are held in a midline position while a needle pierces all the result. Finally, a “frenulum” suture is Collapsed nasal bones can be an exceedingly difﬁcult prob- used to maintain the caudal septum midline. Outfracturing the bones or Dexon that begins at the frenulum and picks up the caudal often fails because the natural tendency of the bones postop septum (2 bites) and is then passed back to the frenulum where is to collapse medially. Often easiest solutions is to simply augment the side of the nasal one nasal bone will be broader than the other, necessitating a bone that is collapsed. However, the autogenous material combination of medial oblique osteotomy and lateral oste- must be soft like the dermis or fascia because the skin overly- otomy to bring the abnormal nasal bone into a more normal ing the nasal bone is exceedingly thin and shows the carti- position. A single layer of fascia that is harvested from the that it is necessary to place an osteotome between it and an temporalis region is our favorite choice (Figs. It adjacent bone to infracture the bony septum back to the mid- must be tied down somehow to prevent contraction and line. Most of the time crookedness of the bony septum is well thickening as mentioned above. The longer crus requires an excision of a small 40, and 41) piece of cartilage from its posterior end (with suture repair) in order that the tripod effect of the tip complex is balanced The crooked nose was one of the greatest challenges in sec- and equal. However, modern techniques have reduced crura, the easiest thing to do is to place a columellar strut it to a relatively simple problem. It is important to recognize, between them to force them into a straighter alignment. The septal mucoperichondrium is put back with through and through quilting sutures (4-0 plain). Doyle splints are applied and kept in place until the plaster splint is removed 6 days later. Figures 42, 43, and 44 show a good example of a patient with crooked nose who had a prior septoplasty for that problem. What was left was converted to an L-shaped strut which was then scored, sutured with horizon- tal mattress sutures, and secured to the upper lateral carti- lages for support. The vertical component of the L-shaped strut was secured in the midline with a frenulum suture. The tip also required lateral crural mattress sutures and interdomal sutures, and a small tip graft was necessary. The algorithm we employ today is the one introduced over a decade ago [14, 15] and has not changed in any signiﬁcant way. Through an open approach (which is almost a must), the upper lateral cartilages are released from the dorsal septum. After inﬁltrating the vestibular skin of the lateral crus, a releasing incision is made between the upper lateral cartilage and lateral crus. Small scissors are used to expand the gap between these two cartilages which length- ens the side wall of the nose. The septal extension graft is applied either on the horizontal or vertical component of the L-shaped strut to maintain the tip cartilages in a caudally displaced location. If the gap between the upper lateral carti- lage and lateral crus is signiﬁcant, an intercartilaginous graft  is placed between the two and is sutured in place. Septal cartilage is ideal as it is thin and will not produce unneces- sary thickening. Figures 50, 51 , 52, and 53 show a good example of a patient with a secondary short nose problem. She had a silicone implant at the ﬁrst surgery and still had a severely short nose. Then a suture (“clocking suture”) is passed from the upper lateral cartilage to the septum to hold the septum in place 658 R. What was left was converted to an L-shaped strut which was then scored, sutured with horizontal mattress sutures, and secured to the upper lateral cartilages for support. The vertical component of the L-shaped strut was secured in the midline with a frenulum suture. The tip also required lateral crural mattress sutures and interdomal sutures, and a small tip graft was necessary. This maneuver lengthens the side wall of the nose and may require an intercartilaginous graft to ﬁll the gap 660 R. By mobilizing the entire ala (including the cephalic aspect), that problem can be mini- Some secondary noses still have a broad nasal base despite mized. Before executing the procedure one should perform the having received a nasal base excision. But in many others, further two ﬁngers to see if the nasolabial angle becomes more obtuse skin removal will either make the nostrils stenotic or the ala than desired. If so, a limit should be placed on how much alar so small that they appear unnatural. When it points straight down and the two axes are parallel, the patient is said to have parentheses alae. It is a potential problem in that if an alar base excision is performed, the axes may turn inward giving the patient a bowling pin deformity Fig. The surgeon is placing the large suture knots too close to the skin sur- also releasing the recently described pyriform ligament face. If necessary, the release can Further excision would have only distorted her alae and extend into the floor of the nasal vault. Alar release was performed to get fur- nylon interalar sutures is then passed from the dermis of ther improvement.
Digital pressure on the globe can superioris buy 50 mg toprol xl amex, and the levator alaeque nasi muscle discount toprol xl 50 mg fast delivery. The scant subcutaneous tissue between the skin and orbicularis in fat contents are gently freed from their postseptal pockets order toprol xl 25 mg amex. With continued elevation and abduction of the globe is located between the Lower Eyelid Blepharoplasty 767 Fig. Speciﬁcally in this region, the fat can be transferred to lie over the inferior orbital rim to camouﬂage the lid-cheek junction and create a more convex contour [5 – 7 ]. The released central and lateral fat pockets are draped over the inferior orbital rim and tacked to the preserved peri- osteum using 6-0 vicryl sutures. In addition to blunting the lid and midface transition, orbital fat ﬁlls the hollowness Fig. The depression as it extends from the medial orbit to the lateral canthus is exposed with the preperiosteal dis- section along and inferior to the lower orbital rim. All central and nasal fat pads; care should be taken to avoid ligamentous attachments overlying the tear trough are injury to this structure. In situations where there is excep- released; insertion of a Desmarres retractor can assist in pro- tional prominence of the infraorbital fat pads, partial exci- viding adequate exposure of the medial orbital rim. Nahai deﬁned by the orbicularis oculi, levator labii superioris, and a levator alaeque nasi. The 6-0 vicryls can once again be used to tack this fat to intact rim periosteum (Fig. If addi- tional ﬁll is needed, the central fat pad can be transferred in a similar manner. Lateral canthal ﬁxation is performed next and is an essen- tial step in performing safe lower lid blepharoplasty and minimizing risk of postoperative lid malposition [8–10]. Canthal anchoring assists in controlling the shape of the eye- lid ﬁssure and counteracting cicatricial healing forces which pull the lower lid inferiorly and lead to scleral show. A canthopexy involves direct ﬁxation of the lower lid to the orbital rim without disruption of the lower canthal tendon. In b a canthoplasty, cantholysis and lid shortening is performed prior to ﬁxation of the lid margin to the orbital rim. In both cases, the new canthus is afﬁxed inside the orbital rim thereby allowing the lid to follow the natural curve of the globe (Fig. The decision to perform a canthopexy versus a canthoplasty is one that can be made intraopera- tively based on the degree of lid laxity. If using a forceps to tuck the lateral lid margin against the orbital rim adequately corrects the lid excess, then a canthopexy alone is adequate. If this maneuver does not result in adequate lid tension, the patient will beneﬁt from lid shortening and formal cantho- plasty. In general, if the lid margin is only able to be dis- tracted 3–4 mm from the globe, canthopexy will sufﬁce, Fig. Note that lower lid is afﬁxed to the inner aspect of the lateral orbital rim Lower Eyelid Blepharoplasty 769 Fig. In cases of a negative vector, the globe is essen- conjunctival surface along the lateral lower lid. Such is the case in patients Mersilene or Prolene double-armed horizontal mattress with prominent eyes or a recessed malar area . By con- suture is placed through the tarsal plate, through the nicked trast, patients with deep set eyes or a prominent bony orbit conjunctiva and back out anteriorly. Those with a negative vector are pre- placed at a 90° angle to this through a portion of the tarsus disposed to downward displacement of the lid following lower and around the canthopexy suture as a locking stitch to pre- lid blepharoplasty. Placing the canthoplasty slightly higher vent cheese wiring of the Prolene through the tarsal plate. The two arms of the canthopexy suture are then placed along If supraplacement of the canthoplasty stitch fails to ade- the inner aspect of the lateral orbital rim periosteum. By quately elevate the lid level, insertion of a spacer graft may passing the sutures deep to superﬁcial the canthus is pulled be necessary. Following canthoplasty placement, the lower posteriorly and superiorly, avoiding a bowstring type defor- lid retractors and conjunctiva are divided with the Bovie, mity. The distance between the two arms of the suture should below the level of the inferior arcade usually 4 mm inferior correspond to the width of the tarsal plate. The spacer material is then sewn along the arms should correct lid laxity and maintain a lower lid posi- posterior lamella to physically elevate the lid margin. If tied too tightly, Materials used can include Enduragen, Alloderm, or autog- clotheslining of the lid below the globe can occur; this is enous ear cartilage. The spacer material is cut to the desired corrected by loosening the suture and stretching the lid supe- height needed for support of the cut lid margin. The freed lid margin is held against the lateral lateral vector to smooth the infraorbital skin. Straight excess at the lateral extent is conservatively marked as a tri- sharp scissors are used to perform a full thickness excision of angle (Fig. The area of redundancy is deepithelialized to the redundant lid, usually measuring 2–4 mm. The same create a lateral pennant of orbicularis muscle that can be double-armed 4-0 Mersilene or Prolene is passed inferiorly anchored to the lateral orbital rim and provide solid suture to superiorly along the cut edge of the tarsal plate. Once ﬁxation of the lower lid during the postoperative healing again, each arm of the suture is passed from deep to superﬁ- phase (Fig. A suture is placed through the muscle and cial along the lateral orbital rim periosteum at the level of the then tacked to the periosteum along the anterior aspect of the midpupillary line and tied to reestablish lid ﬁxation. Any excess muscle is fast absorbing plain is then used to tack the anterior aspect of trimmed. This recreates the natural concavity in the lateral the lower lid gray line to the posterior aspect of the upper lid lid region and acts as an additional means to counteract the gray line in an effort to recreate a sharp lateral canthal angle. Any skin muscle excess along the lid margin itself is of the anterior globe to the inferior orbital rim should be taken also excised with curved sharp scissors, taking care to avoid 770 K. A running 5-0 Prolene is used to close the subciliary and lateral canthotomy incisions. Typically this includes artiﬁcial tears during the day, and a steroid/antibiotic ophthalmic combination ointment at night. Oral steroids, cool compresses, and head elevation are useful to minimize swelling. In addition to the aes- and conservative skin excision minimize complication risk, thetic deformity, these positional changes can lead to dry several other factors alone or in combination can predispose eyes and exposure keratitis. These factors include failure Lower Eyelid Blepharoplasty 771 of the lateral canthal suture ﬁxation, excessive edema or contribute to postoperative lid malposition. A drill hole cantho- proptosis or midface hypoplasia predisposes a patient to this plasty may be necessary. Drill holes are created along the lateral problem due to the inherent imbalance of lower lid support orbital rim and the tarsal plate suture needles may be passed mechanisms. The combination of globe prominence coupled through these for ﬁxation to the bony orbit.
We know that even if our sample were drawn from a normal distribution of values buy toprol xl 50 mg mastercard, sampling variability alone would make it highly unlikely that the observed and expected frequencies would agree perfectly order toprol xl 50mg mastercard. We wonder cheap toprol xl 100mg mastercard, then, if the discrepancies between the observed and expected frequencies are small enough that we feel it reasonable that they could have occurred by chance alone, when the null hypothesis is true. If they are of this magnitude, we will be unwilling to reject the null hypothesis that the sample came from a normally distributed population. If the discrepancies are so large that it does not seem reasonable that they could have occurred by chance alone when the null hypothesis is true, we will want to reject the null hypothesis. The criterion against which we judge whether the discrepancies are “large” or “small” is provided by the chi-square distribution. The first entry in the last column, for example, is computed from 2 2 ð1 À 1:8Þ =1:8 ¼. The appropriate degrees of freedom are 8 (the number of groups or class intervals) À3 (for the three P P restrictions: making Ei ¼ Oi, and estimating m and s from the sample data) ¼ 5. When we compare X ¼ 10:566 with values of x in Appendix Table F, we see that it is less than x2 ¼ 11:070, so that, at the. We conclude that in the sampled population, cholesterol levels may follow a normal distribution. Thus we conclude that such an event is not sufficiently rare to reject the null hypothesis that the data come from a normal distribution. It should be noted that had the mean and variance of the population been specified as part of the null hypothesis in Example 12. Alternatives Although one frequently encounters in the literature the use of chi- square to test for normality, it is not the most appropriate test to use when the hypothesized distribution is continuous. The Kolmogorov–Smirnov test, described in Chapter 13, was especially designed for goodness-of-fit tests involving continuous distributions. Each patient, after trying the new pain reliever for a specified period of time, was asked whether it was preferable to the pain reliever used regularly in the past. Solution: Since the binomial parameter, p, is not specified, it must be estimated from the sample data. A total of 500 patients out of the 2500 patients participating in the study said they preferred the new pain reliever, so that our point estimate of p is p^ ¼ 500=2500 ¼. The expected relative frequencies can be obtained by evaluating the binomial function x 25Àx f ðxÞ¼25Cxð. For example, to find the probability that out of a sample of 25 patients none would prefer the new pain reliever, when in the total population the true proportion preferring the new pain reliever is. The relative frequency of occurrence of samples of size 25 in which no patients prefer the new pain reliever is. Similar calculations yield the remaining expected frequencies, which, along with the observed frequencies, are shown in Table 12. From the data, we compute 2 2 2 2 11 À 2:74 8 À 7:08 0 À 1:73 X ¼ þ þÁÁÁþ ¼ 47:624 2:74 7:08 1:73 The appropriate degrees of freedom are 10 (the number of groups left after combining the first two) less 2, or 8. One degree of freedom is lost because we force the total of the expected frequencies to equal the total observed frequencies, and one degree of freedom is sacrificed because we estimated p from the sample data. Suppose that over a period of 90 days the numbers of emergency admissions were as shown in Table 12. Solution: To obtain the expected frequencies we first obtain the expected relative frequencies by evaluating the Poisson function given by Equation 4. For example, the first expected relative frequency is obtained by evaluating eÀ330 f ð0Þ¼ 0! We may use Appendix Table C to find this and all the other expected rel- ative frequencies that we need. These values along with the observed and expected frequencies and the 2 2 components of X , ðOi À EiÞ =Ei, are displayed in Table 12. This means that we have only nine effective categories for computing degrees of freedom. Since the parameter, l, was specified in the null hypothesis, we do not lose a degree of freedom for reasons of estimation, so that the appropriate degrees of freedom are 9 À 1 ¼ 8. By consulting Appendix 2 Table F, we find that the critical value of x for 8 degrees of freedom and a ¼. We conclude, therefore, that emergency admissions at this hospital may follow a Poisson distribution with l ¼ 3. If the parameter l has to be estimated from sample data, the estimate is obtained by multiplying each value x by its frequency, summing these products, and dividing the total by the sum of the frequencies. The Southern Nevada Health District reported the numbers of vaccine-preventable influenza cases shown in Table 12. We are interested in knowing whether the numbers of flu cases in the district are equally distributed among the five flu season months. We assume that the reported cases of flu constitute a simple random sample of cases of flu that occurred in the district. H0: Flu cases in southern Nevada are uniformly distributed over the five flu season months. If H0 is true, X is distributed approxi- 2 mately as x with ð5 À 1Þ¼4 degrees of freedom. If the null hypothesis is true, we would expect to observe 200=5 ¼ 40 cases per month. The chi-square table provides the observed frequencies, the expected frequencies based on a uniform distribution, and the individual chi-square contribution for each test value. We conclude that the occurrence of flu cases does not follow a uniform distribution. An examination of a simple random sample of 200 individuals yielded the following distribution of the trait: dominant, 43; heterozygous, 125; and recessive, 32. We wish to know if these data provide sufficient evidence to cast doubt on the belief about the distribution of the trait. We assume that the data meet the requirements for the application of the chi-square goodness-of-fit test. H0: The trait is distributed according to the ratio 1:2:1 for homozygous dominant, heterozygous, and homozygous recessive. If H0 is true, the expected frequencies for the three manifestations of the trait are 50, 100, and 50 for dominant, heterozygous, and recessive, respectively. Test the goodness-of-fit of these data to a normal distribution with m ¼ 5:74 and s ¼ 2:01. Uric Acid Observed Uric Acid Observed Determination Frequency Determination Frequency < 1 1 6 to 6. Height in Observed Height in Observed Centimeters Frequency Centimeters Frequency 114 to 115.
A late unrelated electrogram (top) and a presystolic electrogram related to the circuit (bottom) are shown schematically on the left toprol xl 25 mg without a prescription. Exit from the ventricular myocardium is shown by upward arrows buy toprol xl 50 mg on line, and an entrance into the circuit from the pacing site is shown by diagonal inferiorly directed arrow toprol xl 50 mg with mastercard. Entrainment of ventricular tachycardia: explanation for surface electrocardiographic phenomena by analysis of electrograms recorded within the tachycardia circuit. For the same reason, termination with block before this orthodromically entrained electrogram does not mean it was a critical component of the reentrant circuit, as suggested by Waldo and his 326 342 343 colleagues. In the absence of recording the entire diastolic reentrant pathway, I believe that stimulation at the presumed “sites of origin” during the tachycardia is extremely useful. Stimulation from that site can provide evidence of its relationship to the reentrant circuit. If the orthodromically entrained electrogram is outside the circuit, then following cessation pacing at that site, the return cycle should exceed the tachycardia cycle length. If one could record and stimulate from the same pole (tip and 2), it would be ideal, but standard systems are not able to do this. If catheters with a tip-2-5-2 configuration are used, recording from the second and fourth pole of a catheter and stimulation from the first and third pole of the same catheter ensure that the site of stimulation is as close as possible to the site of recording. If all electrodes are 2 mm apart, stimulation from the tip and pole 2 and recording from poles 3 and 4 are reasonable. Thus, we suggest a form of entrainment mapping be used to confirm the relationship of an electrogram to a reentrant circuit. Thus, sites outside of the reentrant circuit may exhibit return cycles equal to or different from the paced cycle length. Thus, once a potential electrogram has been identified as possibly in the isthmus, entrainment or resetting from this site is performed and responses noted. In our laboratory, only if all these three criteria are met is concealed entrainment said to be present. There are limitations to this technique that include (a) differences (albeit slight) of the area from which the second P. In addition, the pacing artifact may obscure the early part of the captured local electrogram. In such instances, a comparable component of the electrogram can be used to measure the return cycle. Unfortunately sometime no electrogram is seen at the St-N + 1 interval, suggesting that pacing was capturing far field tissue. The return cycle, which is equal to the tachycardia cycle length, confirms that the recorded electrogram is within the reentrant circuit. Although the proposed methods of identifying components of a reentrant circuit is useful, focal ablation of all sites defined as in the reentrant circuit may not result in a cure of the tachycardia. Cure of the tachycardia requires ablation of an isthmus bordered by barriers on either side. Because the reentrant circuit incorporates sites outside this critical isthmus, ablation of these “external” sites will not result in cure of the tachycardia, although it may alter either the cycle length or the morphology slightly. The ideal map should therefore be one in which the recorded electrogram comes from within or incorporates the protected isthmus through which the impulses must circulate. If the three criteria proposed above are met, the electrogram most likely is recorded from this zone. We have shown that use of these criteria identifies successful and unsuccessful ablation sites with high predictive 148 44 51 308 accuracy. Proof of localization within this isthmus would require alteration of the tachycardia cycle length and termination by a perturbation at that site. If this could be done by the delivery of subthreshold 354 stimuli, as suggested by Shenasa et al. Similarly, termination by transient application of cryothermia would suggest an isthmus location. There are many limitations to accomplishing all of these components of mapping, not the least of which is patient tolerance. Nevertheless, if one could fulfill all these mapping criteria, one should identify the critical zone of the reentrant pathway, which, if ablated, should cure the arrhythmia. Limitations of catheter position and recording electrodes as well as the inability to predict the amount of current delivered to the reentrant pathway may obviously result in responses that would not meet all the requirements of the ideal ablation site. As noted earlier in this chapter, patients with either dilated or hypertrophic cardiomyopathy demonstrate reasonably normal endocardial electrograms and activation patterns 32 73 (Figs. The vast majority of tachycardias associated with coronary artery disease and prior infarction arise from the left ventricular endocardial or subendocardial areas. Because the bipolar electrogram records endocardial and subendocardial activity, the electrograms can be normal if the tachycardia has an intramural or epicardial origin (see earlier discussion). Using this technique they have demonstrated early activation on the epicardium in patients with Chagas disease and in highly selected patients with inferior infarction, which they targeted for ablation. While epicardial mapping and ablation via the pericardium may be useful in selective cases, there are special factors that must be considered. Significant epicardial fat may lead to inaccurate activation times and reduction of bipolar voltage due to the recording of far field signals. Radiofrequency ablation in the pericardial space is less effective, given poor contact force, the lack of electrode cooling because of absent blood flow (although “cool tip” catheters can be used), and the presence of insulating 403 epicardial fat. In addition, the possibility of damage to the immediately contiguous epicardial coronary arteries, the left phrenic nerve, and the lungs need to be appreciated and avoided. Nonsurgical transthoracic epicardial catheter ablation to treat recurrent ventricular tachycardia occurring late after myocardial infarction. The inferobasal portion of the right ventricle which uses the tricuspid annulus as a fixed barrier is the most common site of an isthmus, while the apical free wall is the least common. The extent of the disease is paralleled by the extent of abnormalities of electrograms in sinus rhythm (see following section entitled Sinus Rhythm Mapping). In such cases, the scar in the right ventricular outflow tract appears to provide at least one potential 157 160 barrier around which the impulse may circulate. For various reasons discussed earlier in this chapter, I do not believe the fascicles have been proven to be part of the reentrant circuit. These tachycardias frequently demonstrate 345 diastolic potentials on the septum leading to a zone of slow conduction, but such potentials have not been universally found. The widely separate potentials are recorded from opposite sides of the ventriculotomy scar. Electrophysiologic characteristics of sustained ventricular tachycardia occurring after repair of tetralogy of Fallot. The mode of initiation, response to stimulation, and effect of drugs on such tachycardias will also provide indirect evidence for the type of mechanism for the arrhythmia. Of importance, however, is the recognition that because tachycardias in cardiomyopathy may be midmyocardial or even subepicardial, the earliest site of activation on the endocardium P. This is important because most standard radiofrequency catheter ablation techniques result in a lesion <2 to 5 mm in depth and could therefore fail to ablate a tachycardia that is subepicardial. Epicardial mapping or use of newer technologies may be necessary to define critical sites for ablation in patients with nonreentrant mechanisms and/or cardiomyopathies in whom intramural or subepicardial sites are critical. The ablation catheter is recording from sites A, B, and C on the schema at the top with recordings shown in the panels on the bottom.
...or by Phone or Mail
PO Box 800
Buffalo, NY 14231 USA
Toll free 1-800-825-2675
Hours 8:30 am 5:00 pm EST M-F